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The scope of this analysis is to estimate the shielding wall, ceiling or equivalent door thicknesses that will be required in the Waste Handling Building to maintain the radiation doses to personnel within acceptable limits. The shielding thickness calculated is the minimum required to meet administrative limits, and not necessarily what will be recommended for the final design. The preliminary
D. Padula
The scope of this analysis is to estimate the shielding wall, ceiling or equivalent door thicknesses that will be required in the Waste Handling Building to maintain the radiation doses to personnel within acceptable limits. The shielding thickness calculated is the minimum required to meet administrative limits, and not necessarily what will be recommended for the final design. The preliminary evaluations will identify the areas which have the greatest impact on mechanical and facility design concepts. The objective is to provide the design teams with the necessary information to assure an efficient and effective design.
D. Padula
Shield Through Rejuvenated Stage Volcanism On Kauai and Niihau, Hawaii
NASA Astrophysics Data System (ADS)
Kauai and Niihau are the northwesternmost large islands in the Hawaiian chain and consist of shield, rare postshield, and abundant rejuvenated stage lavas. We present new geochronological, geochemical and isotopic data for all phases of volcanic activity on the adjacent islands. K-Ar ages show Niihau shield volcanism occurred from 6.3-4.4 Ma, and K-Ar and new Ar-Ar ages for postshield volcanism range from 5.4-4.7 Ma. Kauai shield volcanism (K-Ar) overlaps with shield volcanism on Niihau. A new Ar-Ar age for a Kauai postshield dike is 4.4 Ma, older than previously-dated postshield lavas (3.95-3.58 Ma). New Ar-Ar ages show that Kauai rejuvenated stage volcanism began prior to 3.42 Ma (Izuka & Sherrod, 2011), compared to ~2.3 Ma on Niihau. Tholeiitic shield lavas from Kauai vary only slightly in trace element chemistry but have variable isotopic compositions. Subtle trends in some trace element and isotopic ratios between Napali Member shield lavas from the east and west side of Kauai support the two-shield hypothesis of Holcomb et al. (1997). Shield lavas from Niihau are chemically similar to those on Kauai, although Niihau tholeiites extend to higher 143Nd/144Nd ratios. Onland and submarine postshield rocks from Niihau are slightly more alkaline and LREE-enriched compared to shield lavas, but postshield rocks from Kauai are more chemically evolved, more LREE-enriched, and have more depleted Sr and Nd isotopic signatures than Kauai tholeiites. Postshield rocks on Kauai overlap in apparent age with lavas that are chemically like later rejuvenated stage lavas, suggesting either interfingering of the chemically distinct lavas or problems with the K-Ar ages. Rejuvenated stage lavas from the two islands differ dramatically; Kauai lavas are alkaline, LREE-enriched, and have even more depleted Sr and Nd isotopic compositions than postshield lavas, whereas Niihau lavas are only mildly alkaline, have lower REE abundances than postshield basalts, but isotopically are like Kauai rejuvenated rocks. Niihau rejuvenated lavas are shifted to slightly higher 87Sr/86Sr at a given 143Nd/144Nd than Kauai rejuvenated lavas, consistent with an enhanced carbonate component in their source (Dixon et al., 2008). Rejuvenated stage lavas have a diagnostic Sr and Nd isotopic signature on both Kauai and Niihau, but on Kauai the isotopic shift begins during the postshield stage. For Kauai, age and geochemical data suggest that volcanic activity was near-continuous from shield to postshield to rejuvenated stage, with a change in mantle source at the postshield to rejuvenated transition. On Niihau, a prominent erosional and age gap separates onland shield and postshield rocks from the rejuvenated stage lavas, with the change in mantle sources at the beginning of the rejuvenated stage. ROV dives on six vents off the NW coast of Niihau recovered a suite of highly alkaline basanites with REE patterns similar to Kauai rejuvenated lavas but with isotopic ratios spanning the range of Niihau shield and postshield lavas. These alkaline lavas are highly vesicular and more altered than rejuvenated stage Niihau rocks, are undated, but may straddle the postshield to rejuvenated stage transition. No equivalents exist at other Hawaiian volcanoes.
Cousens, B.; Clague, D. A.
Gamma -Ray Shielding Effect of Various Building Materials.
National Technical Information Service (NTIS)
It is necessary to know the gamma -ray attenuation coefficients and the dose buildup factors for various building materials in order to evaluate the gamma -ray shielding factor of the residential houses in a reactor accident. As a matter of fact, however,...
Y. Yamaguchi K. Minami S. Ohtani
Investigations of some building materials for ?-rays shielding effectiveness
NASA Astrophysics Data System (ADS)
For construction of residential and non-residential buildings bricks are used as building blocks. Bricks are made from mixtures of sand, clay, cement, fly ash, gypsum, red mud and lime. Shielding effectiveness of five soil samples and two fly ash samples have been investigated using some energy absorption parameters (Mass attenuation coefficients, mass energy absorption coefficients, KERMA (kinetic energy released per unit mass), HVL, equivalent atomic number and electron densities) firstly at 14 different energies from 81-1332 keV then extended to wide energy range 0.015-15 MeV. The soil sample with maximum shielding effectiveness has been used for making eight fly ash bricks [(Lime)0.15 (Gypsum)0.05 (Fly Ash)x (Soil)0.8-x, where values of x are from 0.4-0.7]. High Purity Germanium (HPGe) detector has been used for gamma-ray spectroscopy. The elemental compositions of samples were analysed using an energy dispersive X-ray fluorescence (EDXRF) spectrometer. The agreements of theoretical and experimental values of mass attenuation coefficient have been found to be quite satisfactory. It has been verified that common brick possess the maximum shielding effectiveness for wide energy range 0.015-15 MeV. The results have been shown graphically with some useful conclusions for making radiation safe buildings.
Mann, Kulwinder Singh; Kaur, Baljit; Sidhu, Gurdeep Singh; Kumar, Ajay
Shielding study for fast-burst reactor building
A study was conducted to evaluate the radiation levels and the response of various diagnostic components in and around the building that houses the Godiva IV fast-burst reactor assembly. In a typical operation of 1 MW-s (3.6{approx}10f'is{approx}s ions) in a 50 ps fwhm burst the peak power approaches 100,000 MW. The unshielded dose at 3 m is about 500 Rem. The results will be used to evaluate the radiation levels and shielding requirements for a new facility, and to anticipate problems with new safety, security, and diagnostic instrumentation. The study was required because of the difficulty of making accurate calculations, the intensity of the radiation, the mixed neutron and gamnta-ray source terms, and the complex nature of the structure. In addition to detailed dosimetry, attention was paid to the evaluation of spurious electromagnetic and radiofrequency signals produced in detectors, cables, and conduits.
Rees, B. G. (Brian G.); Malenfant, R. E. (Richard E.)
Verification of some building materials as gamma-ray shields.
The shielding properties for gamma rays of a few low Z materials were investigated. The values of the mass attenuation coefficient, equivalent atomic number, effective atomic number, exposure buildup factor and energy absorption buildup factor were calculated and used to estimate the shielding effectiveness of the samples under investigation. It has been observed that the shielding effectiveness of a sample is directly related to its effective atomic number. The shielding character of any sample is a function of the incident photon energy. Good shielding behaviour has been verified in soil samples in the photon energy region of 0.015-0.30 MeV and of dolomite in 3-15 MeV. The results have been shown graphically with more useful conclusions. PMID:22223719
Mann, Kulwinder Singh; Singla, Jyoti; Kumar, Vipan; Sidhu, G S
North Kona slump: Submarine flank failure during the early(?) tholeiitic shield stage of Hualalai Volcano
The North Kona slump is an elliptical region, about 20 by 60 km (1000-km2 area), of multiple, geometrically intricate benches and scarps, mostly at water depths of 2000-4500 m, on the west flank of Hualalai Volcano. Two dives up steep scarps in the slump area were made in September 2001, using the ROV Kaiko of the Japan Marine Science and Technology Center (JAMSTEC), as part of a collaborative Japan-USA project to improve understanding of the submarine flanks of Hawaiian volcanoes. Both dives, at water depths of 2700-4000 m, encountered pillow lavas draping the scarp-and-bench slopes. Intact to only slightly broken pillow lobes and cylinders that are downward elongate dominate on the steepest mid-sections of scarps, while more equant and spherical pillow shapes are common near the tops and bases of scarps and locally protrude through cover of muddy sediment on bench flats. Notably absent are subaerially erupted Hualalai lava flows, interbedded hyaloclastite pillow breccia, and/or coastal sandy sediment that might have accumulated downslope from an active coastline. The general structure of the North Kona flank is interpreted as an intricate assemblage of downdropped lenticular blocks, bounded by steeply dipping normal faults. The undisturbed pillow-lava drape indicates that slumping occurred during shield-stage tholeiitic volcanism. All analyzed samples of the pillow-lava drape are tholeiite, similar to published analyses from the submarine northwest rift zone of Hualalai. Relatively low sulfur (330-600 ppm) and water (0.18-0.47 wt.%) contents of glass rinds suggest that the eruptive sources were in shallow water, perhaps 500-1000-m depth. In contrast, saturation pressures calculated from carbon dioxide concentrations (100-190 ppm) indicate deeper equilibration, at or near sample sites at water depths of -3900 to -2800 m. Either vents close to the sample sites erupted mixtures of undegassed and degassed magmas, or volatiles were resorbed from vesicles during flowage downslope after eruption in shallow water. The glass volatile compositions suggest that the tholeiitic lavas that drape the slump blocks were erupted either (1) early during shield-stage tholeiitic volcanism prior to emergence of a large subaerial edifice, or alternatively (2) from submarine radial vents during subaerial shield-building. Because no radial vents have been documented on land or underwater for the unbuttressed flanks of any Hawaii volcano, alternative (1) is favored. In comparison to other well-documented Hawaiian slumps and landslides, North Kona structures suggest a more incipient slump event, with smaller down-slope motions and lateral displacements.
Lipman, P. W.; Coombs, M. L.
LPT. Shield test control building (TAN645). Typical interior of office/conference ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
LPT. Shield test control building (TAN-645). Typical interior of office/conference area. Camera facing northeast. INEEL negative no. HD-40-6-1 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
IET distant contextual view of TAN620, shielded control building. facing ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
IET distant contextual view of TAN-620, shielded control building. facing northwest. non-IET related monitoring device in foreground. INEEL negative no. HD-21-8-2 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
Hawaiian Shield Stage Submarine Volcaniclastics: Insights From HSDP Core
NASA Astrophysics Data System (ADS)
Ocean island volcanoes are traditionally associated with the non-explosive eruption of fluid lavas, but volcaniclastic rocks comprise a significant portion of many submarine shield volcanoes. Deep drilling (3,098 m) by the Hawaiian Scientific Drilling Project (HSDP) into the flank of Mauna Kea volcano has exposed the volcaniclastics within the pedestals of a Hawaiian volcano that were previously poorly known. The HSDP continuously cored 2,019 m of submarine Mauna Kea deposits with �95% recovery and revealed that volcaniclastics comprise �55% of this section. The shallow submarine section consists of �80% volcaniclastics interbedded with thin ( �3 m) massive lava flows and the deep section is �35% volcaniclastics interbedded with packages of pillow lavas up to 180 m thick. Throughout the submarine section, the volcaniclastics can occur in thick packages up to �100 m. The emplacement of submarine volcaniclastics is not well understood. Possible origins include primary fragmentation of lava via magmatic explosivity and magma-water interactions, and secondary fragmentation via erosion. Secondary transport of material down the steep submarine flanks by gravity flows is expected to be common, as is reworking by currents. Emplacement processes are predicted to evolve as the volcano shoals. In this study major element analyses of glassy clasts in the volcaniclastics are used to distinguish monomict and polymict assemblages, which can indicate primary versus secondary fragmentation. Clast shapes reflect fragmentation mechanisms and secondary processes and this study attempts to improve on this approach with quantitative analysis of clast shapes for the HSDP volcaniclastics and for samples of known origin. The first documentation of the textures of the Mauna Kea volcaniclastics, integrated with geochemistry, petrography, and quantitative clast shape analysis and inferences about their origins and modes of transport and deposition will be presented to better understand the shoaling of Hawaiian volcanoes.
Bridges, K. P.; Garcia, M.; Houghton, B.; Thordarson, T.
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
PLUG STORAGE BUILDING, TRA-611, AWAITS SHIELDING SOIL TO BE PLACED OVER PLUG STORAGE TUBES. WING WALLS WILL SUPPORT EARTH FILL. MTR, PROCESS WATER BUILDING, AND WORKING RESERVOIR IN VIEW BEYOND PLUG STORAGE. CAMERA FACES NORTHEAST. INL NEGATIVE NO. 2949. Unknown Photographer, 7/30/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID
Multivariate modeling for a multi-stage green building framework
Green building is a sustainable concept to reduce enviromental impact. Decision-making for green building is a complex task. We present a multi-stage green building framework that will guide future development of a comprehensive multiple stage, multiple objective (MSMO) decision-making framework. Various software tools can assist in studying components of our multi-stage framework. We seek to simultaneously explore building options via
Pin Kung; Victoria C. P. Chen; Anthony Robinson
SPERTI Reactor Pit Building (PER605). Earth shielding protect adjacent Instrument ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
SPERT-I Reactor Pit Building (PER-605). Earth shielding protect adjacent Instrument Cell (PER-606). Security fencing surrounds complex, to which gate entry is provided next to Guard House (PER-607). Note gravel road leading to control area. Earth-covered conduit leads from instrument cell to terminal building out of view. Photographer: R.G. Larsen. Date: June 22, 1955. INEEL negative no. 55-1701 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID
IET entrance to control building (TAN620) from shielded roadway. facing ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
IET entrance to control building (TAN-620) from shielded roadway. facing west. note corrugated steel wall, curbs along roadway, drainage grate. room beyond is turnaround area. INEEL negative no. HD-21-6-1 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
LPT. Shield test facility assembly and test building (TAN646), south ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
LPT. Shield test facility assembly and test building (TAN-646), south end of EBOR helium wing. Camera facing north. Monorail protrudes from upper-level door. Rust marks on concrete wall are from stack. Metal shed is post-1970 addition. INEEL negative no. HD-40-8-1 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
HOT CELL BUILDING, TRA-632. SHIELDED WINDOWS HAVE BEEN INSTALLED. MANIPULATORS AWAIT ATTACHMENT TO HAND CONTROLS. INL NEGATIVE NO. 9001. Unknown Photographer, photo is identified as taken 10/28/1953, but it may be an error as it shows progress since ID-33-G-266 of same date. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
HOT CELL BUILDING, TRA-632. SECTION DETAILS OF SHIELD CONCRETE, OPERATING WINDOWS, CHARGING HOLES. IDAHO OPERATIONS OFFICE MTR-632-IDO-5, 11/1950. INL INDEX NO. 531-0632-60-396-110564, REV. 2. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID
LOFT. Reactor apparatus leaves A&M building (TAN607). Shielded locomotive has ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
LOFT. Reactor apparatus leaves A&M building (TAN-607). Shielded locomotive has aerojet logo, which replaced old general electric logo, pulls reactor from assembly shop on dolly. Camera facing easterly. Date: 1973. INEEL negative no. 73-3700 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
LPT. Shield test facility test building interior (TAN646). Camera points ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
LPT. Shield test facility test building interior (TAN-646). Camera points down into interior of north pool. Equipment on wall is electronical bus used for post-1970 experiment. Personnel ladder at right. INEEL negative no. HD-40-9-1 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
LPT. Shield test facility test building interior (TAN646). Camera facing ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
LPT. Shield test facility test building interior (TAN-646). Camera facing south. Distant pool contained EBOR reactor; near pool was intended for fuel rod storage. Other post-1970 activity equipment remains in pool. INEEL negative no. HD-40-9-4 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
Shielding study for fast-burst reactor building
A study was conducted to evaluate the radiation levels and the response of various diagnostic components in and around the building that houses the Godiva IV fast-burst reactor assembly. In a typical operation of 1 MW-s (3.610f'iss ions) in a 50 ps fwhm burst the peak power approaches 100,000 MW. The unshielded dose at 3 m is about 500 Rem.
B. G. Rees; R. E. Malenfant
Three-dimensional analysis of AP600 standard plant shield building roof
The AP600 passive containment vessel is surrounded by a concrete cylindrical shell covered with a truncated conical roof. This roof supports the passive containment cooling system (PCS) annular tank, shield plate and other nonstructural attachments. When the shield building is subjected to different loading combinations as defined in the Standard Review Plan (SRP), some of the sections in the shield building could experience forces in excess of their design values. This report summarized the three-dimensional finite element analysis that was conducted to review the adequacy of the proposed Westinghouse shield building design. The ANSYS finite element software was utilized to analyze the Shield Building Roof (SBR) under dead, snow, wind, thermal and seismic loadings. A three-dimensional model that included a portion of the shield building cylindrical shell, the conical roof and its attachments, the eccentricities at the cone-cylinder connection and at the compression ring and the PCS tank was developed. Mesh sensitivity studies were conducted to select appropriate element size in the cylinder, cone, near air intakes and in the vicinity of the eccentricities. Also, a study was carried out to correctly idealize the water-structure interaction in the PCS tank. Response spectrum analysis was used to calculate the internal forces at different sections in the SBR under Safe Shutdown Earthquake (SSE). Forty-nine structural modes and twenty sloshing modes were used. Two horizontal components of the SSE together with a vertical component were used. Modal stress resultants were combined taking into account the effects of closely spaced modes. The three earthquake directions were combined by the Square Root of the Sum Squares method. Two load combinations were studied. The load combination that included dead, snow, fluid, thermal and seismic loads was selected to be the most critical. Interaction diagrams for critical sections were developed and used to check the design adequacy. The results demonstrated that provided area of steal on each face of several sections of the AP600 SBR was inadequate. This was also noticed when comparing the total provided area of steel per section, i.e., the area of steel on both faces. The discrepancy between Westinghouse results and these reported herein could have resulted from the different finite element mesh sizes and the assumption used in Westinghouse design.
Greimann, L.; Fanous, F.; Safar, S.; Khalil, A.; Bluhm, D.
LPT. Shield test facility assembly and test building (TAN646). East ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
LPT. Shield test facility assembly and test building (TAN-646). East facade of ebor helium wing addition. Camera facing west. Note asbestos-cement siding on stair enclosure and upper-level. Concrete siding at lower level. Metal stack. Monorail protrudes from upper level of south wall at left of view. INEEL negative no. HD-40-7-4 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
Using a single-stage GM cooler to augment the cooling of the shields and leads of a magnet cooled with two-stage coolers
NASA Astrophysics Data System (ADS)
The temperature of a superconducting magnet shield and the tops of HTS leads for that magnet are determined by the heat flow into the first-stages of two-stage coolers used to cool the magnet. When the heat flow into the cooler first-stages is excessive, the shield and cold mass intercept temperature may be too high. This can lead to a failure of the HTS lead. If the heat flow into the shield and the HTS leads is too high, one can remove the excess heat using a single stage cooler. A test of a MICE spectrometer solenoid cooled with three two-stage pulse tube coolers in 2009 demonstrated what happens when the heat loads into the pulse tube cooler first-stages were excessive. One result was that the HTS lead furthest from the three pulse tube coolers burned out. LBNL added a single stage GM cooler at the end of the lead string furthest from the pulse tube coolers. The copper leads from room temperature were replaced with more efficient leads. The combination of the two changes reduced the pulse tube cooler first stage temperature, the lead temperature, and the temperature of the magnet shield.
Green, Michael; Virostek, Steve
Tectonic-magmatic stages of shield evolution: the Pan-African belt in northeastern Egypt
NASA Astrophysics Data System (ADS)
The Arabian-Nubian shield illustrates an example of plate tectonics during the Pan-African orogenic event (ca. 950-550 Ma); it is considered one of the most remarkable Proterozoic shield areas yet known. Although there is now a general agreement that the shield has evolved by a series of magmatic arcs and terrain accretion, the evolution of its northernmost part exposed in northeastern Egypt remains controversial. Two contrasting tectonic models have been proposed for the evolution of this region: regional crustal extension and magmatic-arc regimes. There is no convincing evidence of older (Archean) sialic materials within the region, although the region is flanked by Archean crust. The Neoproterozoic crustal components exposed in northeastern Egypt preserve a record for its evolution. A large gabbro-diorite-tonalite complex (GDT, 881 Ma) emplaced during the early stage of the Pan-African orogeny is geochemically primitive, exhibits a low initial {87Sr }/{86Sr } ratio (0.704) and shows trace-element characteristics of oceanic-arc-related lavas. The GDT complex was produced (by fractionation) from a mantle-derived tholeiitic magma formed within an island-arc tectonic environment. A synorogenic stage characterized by extensive volcanism that produced the Dokhan volcanic suite (DVS, 620 Ma) forms a continuous basalt to rhyolitic ignimbrite calc-alkaline magma series, exhibiting features of arc-related volcanism, with REE profiles similar overall to Andean andesites and ignimbrites. The Dokhan suite was produced in a continental-arc setting. A granodiorite-adamellite-leucogranite composite batholith (552 Ma) emplaced during the late stage of the Pan-African orogeny exhibits typical features of I-type complexes, trace element traits of volcanic-arc granites, and is also interpreted to have been formed in an Andean-type setting. A trondhjemite pluton was also formed at this late orogenic stage, by partial melting of GDT host rocks at depth. Cooling and relaxation of the newly formed Pan-African crust caused extensive fracturing, which was followed by intrusion of NE-SW- and NNW-SSE-trending dyke swarms at 493 Ma. This episode marks a fundamental inversion from orogenic compressional to anorogenic extensional processes around the Neoproterozoic-Paleozoic boundary. Anorogenic magmatism was locally associated with such extension-induced structures. The Mount Gharib peralkaline granite (476 Ma), for example, exhibits trace element traits of A-type, within-plate granites, and a high initial {87Sr }/{86Sr } ratio (0.711), and was formed in a rift environment. Thus, the region is characterized by lengthy episodes of discontinuous subduction (� 880-550 Ma), during which it evolved to form a primitive crust by early Pan-African island arcs and late Pan-African continental arcs. This was followed by an even longer period of crustal extension (� 550-90 Ma) that produced localized anorogenic magmatism.
Abdel-Rahman, Abdel-Fattah M.
Albari granodiorite - a typical calcalkaline diapir of volcanic arc stage from the Arabian Shield
NASA Astrophysics Data System (ADS)
Granodiorite rocks of the Arabian Shield are generally considered to be collision-related granitoids. However, there are some granodiorites that were formed during the volcanic arc stage. Major and trace elements studies are carried out on Albari diapiric granodiorite to reveal its tectonic environment. This intrusive rock type is common in the Taif arc province (Mahd adh Dhahab quadrangle) of the Asir microplate near the border of the southeast dipping subduction zone that ended up with arc-arc collision (Asir-Hijaz microplates) along the now known Bir Umq suture zone. The granodiorite exhibits a calcalkaline trend on ternary AFM and K 2O?Na 2O?CaO diagrams. Tectonic discrimination diagrams using multicationic parameters (R1 = 4Si?ll(Na+K)?2(Fe+Ti); R2 = 6Ca+2Mg+Al), SiO 2-trace elements (Nb, Y, Rb), and Y versus Nb and Rb versus (Y+Nb) indicate a destructive active plate margin or volcanic arc stage tectonic environment. Albari calcalkaline granodiorite might have been derived directly from partial melting of subducted oceanic crust or overlying mantle contaminated with variable amounts of intermediate (quartz diorite, diorite, tonalite, trondhjemite) early and late volcanic arc-related plutonic country rocks.
Radain, Abdulaziz A.
Linear attenuation coefficient and build up factor of MCP-96 alloy for radiation shielding and protection
NASA Astrophysics Data System (ADS)
Build-up factors and linear attenuation coefficients of MCP-96 alloy are determined for radiation shielding and protection, using ^60Co and ^137Cs gamma emitters. A narrow collimated beam of ?-rays is passed through various thicknesses of MCP-96 alloy and the attenuation in the intensity of the beam is determined. The thickness of the 4 x 4 cm^2 blocks varies from 0.5 cm to 6 cm. Plotting the thickness of the alloy and the corresponding intensity of the beam allowed us to determine its linear attenuation coefficient. The narrow beam geometry is then replaced by broad beam geometry by removing the collimator and the radiation beam is able to interact with the MCP-96 alloy at all possible positions facing the radiation source. Additional radiations obtained by the detector as a result from the scattering of radiation develops the build-up factor. The buildup factor is then calculated using the attenuated beam received by the detector in the broad beam geometry and in the narrow beam geometry. The buildup factor is found to be dependent on the thickness of the MCP-96 attenuator, the beam energy and the source to attenuator distance. These values are providing ways for dose correction in radiation oncology and radiation shielding and protection when MCP-96 is used as tissue compensator or for radiation protection purposes.
Hopkins, Deidre; Maqbool, Muhammad; Islam, Mohammed
The TRADE experiment: shielding calculations for the building hosting the subcritical system.
The TRADE project (TRiga Accelerator Driven Experiment), to be performed at the existing TRIGA reactor at ENEA Casaccia, has been proposed as a validation of the accelerator-driven system (ADS) concept. TRADE will be the first experiment in which the three main components of an ADS--the accelerator, spallation target and sub-critical blanket--are coupled at a power level sufficient to encounter reactivity feedback effects. As such, TRADE represents the necessary intermediate step in the development of hybrid transmutation systems, its expected outcomes being considered crucial--in terms of proof of stability of operation, dynamic behaviour and licensing issues--for the subsequent realisation of an ADS Transmutation Demonstrator. An essential role in the feasibility study of the experiment is played by radioprotection calculations. Such a system exhibits new characteristics with respect to a traditional reactor, owing to the presence of the proton accelerator. As beam losses always occur under normal operating conditions of an accelerator, shielding studies need to be performed not only around the reactor but also along the beam line from the accelerator to the spallation target. This paper illustrates a preliminary evaluation, using Monte Carlo methods, of the additional shielding to be located around the reactor structures, the beam transport line and the existing reactor building to allow access into the reactor hall and to restrict the doses outside to their legal limits. PMID:16381710
Burn, K W; Carta, M; Casalini, L; Kadi, Y; Monti, S; Nava, E; Palomba, M; Petrovich, C; Picardi, L; Rubbia, C; Troiani, F
Building a new kind of graded-Z shield for Swift's burst alert telescope
NASA Astrophysics Data System (ADS)
The Burst Alert Telescope (BAT) on Swift has a graded-Z Shield that closes out the volume between the coded aperture mask and the Cadmium-Zinc-Telluride (CZT) detector array. The purpose of the 37-kilogram shield is to attenuate gamma rays that have not penetrated the coded aperture mask of the BAT instrument and are therefore a major source of noise on the detector array. Unlike previous shields made from plates and panels, this shield consists of multiple layers of thin metal foils (lead, tantalum, tin, and copper) that are stitched together much like standard multi-layer insulation blankets. The shield sections are fastened around BAT, forming a curtain around the instrument aperture. Strength tests were performed to validate and improve the design, and the shield will be vibration tested along with BAT in late 2002. Practical aspects such as the layup design, methods of manufacture, and testing of this new kind of graded-Z Shield are presented.
Robinson, David W.
Building A New Kind of Graded-Z Shield for Swift's Burst Alert Telescope
NASA Technical Reports Server (NTRS)
The Burst Alert Telescope (BAT) on Swift has a graded-Z Shield that closes out the volume between the coded aperture mask and the Cadmium-Zinc-Telluride (CZT) detector array. The purpose of the 37 kilogram shield is to attenuate gamma rays that have not penetrated the coded aperture mask of the BAT instrument and are therefore a major source of noise on the detector array. Unlike previous shields made from plates and panels, this shield consists of multiple layers of thin metal foils (lead, tantalum, tin, and copper) that are stitched together much like standard multi-layer insulation blankets. The shield sections are fastened around BAT, forming a curtain around the instrument aperture. Strength tests were performed to validate and improve the design, and the shield will be vibration tested along with BAT in late 2002. Practical aspects such as the layup design, methods of manufacture, and testing of this new kind of graded-Z Shield are presented.
Robinson, David W.
Building A New Kind of Graded-Z Shield for Swift's Burst Alert Telescope.
National Technical Information Service (NTIS)
The Burst Alert Telescope (BAT) on Swift has a graded-Z Shield that closes out the volume between the coded aperture mask and the Cadmium-Zinc-Telluride (CZT) detector array. The purpose of the 37 kilogram shield is to attenuate gamma rays that have not p...
D. W. Robinson
Building information model based energy\\/exergy performance assessment in early design stages
Due to the rising awareness of climate change and resulting building regulations worldwide, building designers increasingly have to consider the energy performance of their building designs. Currently, performance simulation is mostly executed after the design stage and thus not integrated into design decision-making. In order to evaluate the dependencies of performance criteria on form, material and technical systems, building performance
Arno Schlueter; Frank Thesseling
92. Neg. No. F142, Mar 29, 1932, INTERIORASSEMBLY BUILDING, STAGE ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
92. Neg. No. F-142, Mar 29, 1932, INTERIOR-ASSEMBLY BUILDING, STAGE AND EXHIBITION ROOM - Ford Motor Company Long Beach Assembly Plant, Assembly Building, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA
Building a new kind of graded-Z shield for Swift's burst alert telescope
The Burst Alert Telescope (BAT) on Swift has a graded-Z Shield that closes out the volume between the coded aperture mask and the Cadmium-Zinc-Telluride (CZT) detector array. The purpose of the 37-kilogram shield is to attenuate gamma rays that have not penetrated the coded aperture mask of the BAT instrument and are therefore a major source of noise on the
David W. Robinson
Simple tool to evaluate energy demand and indoor environment in the early stages of building design
A simplified building simulation tool to evaluate energy demand and thermal indoor environment in the early stages of building design is presented. Simulation is performed based on few input data describing the building design, HVAC systems and control strategies. Hourly values for energy demand and indoor temperature are calculated based on hourly weather data. Calculation of the solar energy transmitted
Toke Rammer Nielsen
Numerical analysis and experiment on noise shielding effects of eaves\\/louvers attached on building facade
Some high-rise buildings located in urban areas of Japan have eaves on their fa�ades for the aim of fireproofing in accordance with The Building Standard Law of Japan. From the environmental viewpoint, such eaves are regarded as an efficient measure for mitigating thermal loads on the buildings owing to solar shading. Besides that, the eaves can be an efficient countermeasure
Rino Otani; Takumi Asakura; Shinichi Sakamoto
Petrology and geochemistry of shield-building and post-erosional lava series of Samoa: implications for mantle heterogeneity and magma genesis
Samoan shield-building lavas are more alkalic than Hawaiian shield basalts, but a transition from less- to more-alkalic flows may be identified in the Pago Shield of Tutuila. This transition is not gradational, but rather consists of alternating less- and more-alkalic interbedded flows, indicating little magma mixing during this period, a conclusion supported by extreme isotopic heterogeneity in these flows. Further evolution of the Pago shield lava compositions is controlled by fractionation of olivine to produce increasingly Si-enriched differentiates. Samoan post-erosional lavas are distinct from Samoan shield-building lavas. They are strongly Si-undersaturated and unfractionated, and show higher YXSr/YWSr and SXPb/SUPb and lower UTNd/ UUNd isotopic ratios than shield-building lavas. Whereas shield-building lavas have isotopic compositions similar to the Society Islands, post-erosional lavas may represent mixing of this shield source with an enriched end member, tentatively identified as recycled crustal material. Compositional variation within the post-erosional lavas is controlled by source differences evident in rare earth element and isotopic compositions, and minor fractionation of olivine, Ti-magnetite, and clinopyroxene. The close spacing of vents along a 282-km-long rift zone parallel to the trend of the island chain, and the anomalously large volume of post-erosional lavas are inconsistent with a plume origin. Two types of ultramafic xenoliths are included in Samoan post-erosional lavas: harzburgite-lherzoilite nodules showing porphyroclastic and equigranular-mosaic textures, and wehrlite-dunites showing tectonized cumulate textures.
Wright, E.
Prediction of building envelope performance in the design stage: an application for office buildings
Building envelope should provide visual, thermal and acoustical comfort in accordance with the function of the room. The material properties of the translucent-window- and opaque components-wall- of the building envelope and the ratio of these components are effective in the establishment of comfort conditions in an interior. The perfection of the building envelope design is highly related to the consideration
Rengin �nver; Ne?e Y. Akda?; G�lay Z. Gedik; Leyla D. �zt�rk; Zerhan Karabiber
Volcaniclastic sediments recovered from the clastic apron of Gran Canaria during Leg 157 provide a rare opportunity to study basaltic volcanism from the early shield-building phase of an oceanic island. Infrared spectroscopic analyses of trapped melt (glass) inclusions from Miocene hyaloclastites, many of which are picritic, generally show very low pre-eruptive dissolved H2O concentrations (0.08 to ~0.2 wt% H2O). Two
Paul J. Wallace
Energy graphics: profiling a building in the pre-design stage
The design stage is the best time to improve building efficiency by considering site, orientation, landscaping, building shape, and windows in the early planning process. The Energy Graphics technique uses about 20 variables categorized under climate, building design, and occupant needs to get a rough estimate of building performance and identify potential problems and energy-saving opportunities before construction begins. The technique is simple to operate using a desktop computer to analyze internal heat gain and loss. The architect can make design changes on the basis of the computer graphs. 9 figures. (DCK)
Kurtz, J.M.
Lithospheric Expressions of the Precambrian Shield, Mesozoic Rifting, and Cenozoic Subduction and Mountain Building in Venezuela
NASA Astrophysics Data System (ADS)
The Caribbean (CAR)-South American (SA) plate boundary in Venezuela is a broad zone of faulting and diffuse deformation. GPS measurements show the CAR moving approximately 2 cm/yr relative to SA, parallel to the strike slip fault system in the east, with more oblique convergence in the west (Weber et al., 2001) causing the southern edge of the Caribbean to subduct beneath northwestern South America. The west is further complicated by the motion of the triangular Maracaibo block, which is escaping northeastward relative to SA along the Bocono and Santa Marta Faults. In central and eastern Venezuela, plate motion is accommodated by transpression and transtension along the right lateral San Sebastian- El Pilar strike-slip fault system. The strike-slip system marks the northern edge of coastal thrust belts and their associated foreland basins. The Archean-Proterozoic Guayana Shield, part of the Amazonian Craton, underlies southeastern and south-central Venezuela. We used the 87 station Venezuela-U.S. BOLIVAR array (Levander et al., 2006) to investigate lithospheric structure in northern South America. We combined finite-frequency Rayleigh wave tomography with Ps and Sp receiver functions to determine lithosphere-asthenosphere boundary (LAB) depth. We measured Rayleigh phase velocities from 45 earthquakes in the period band 20-100s. The phase velocities were inverted for 1D shear velocity structure on a 0.5 by 0.5 degree grid. Crustal thickness for the starting model was determined from active seismic experiments and receiver function analysis. The resulting 3D shear velocity model was then used to determine the depth of the LAB, and to CCP stack Ps and Sp receiver functions from ~45 earthquakes. The receiver functions were calculated in several frequency bands using iterative deconvolution and inverse filtering. Lithospheric thickness varies by more a factor of 2.5 across Venezuela. We can divide the lithosphere into several distinct provinces, with LAB depth reflecting the signatures of the Precambrian craton in the south, Mesozoic rifting in central Venezuela, and Neogene subduction and orogenesis in both the northeast and northwest. Specifically, LAB depth varies from 110-130 km beneath the Guayana Shield, in agreement with finite-frequency body wave tomography (Bezada et al., 2010b). To the north beneath the Serrania del Interior and Maturin Basin the Rayleigh waves image two high velocity features to depths of 200 km. The northernmost, beneath the Serrania, corresponds to the top of the subducting Atlantic plate, in agreement with P-wave tomography that images the Atlantic plate to transition zone depths. Another localized high velocity feature extending to ~200 km depth lies to the south. We speculate that this is a lithospheric drip caused by destabilization of the SA lithospheric caused by Atlantic subduction. Immediately to the west beneath the Cariaco basin the LAB is at ~50 km, marking the top of a pronounced low velocity zone. The thin lithosphere extends southwestward from the Cariaco Basin beneath the Mesozoic Espino Graben to the craton. To the west the LAB deepens to ~80 km beneath the Barinas Apure Basin and then to ~90 km beneath the Neogene Merida Andes and Maracaibo block.
Levander, A.; Masy, J.; Niu, F.
S>Building factors for iron shields, lead shields, and laminated iron-; lead shields (1.7 mean free paths of lead and 1 to 3 mean free paths of iron per ; lamination) were determined for shield thicknesses up to 6.8 mean free paths of ; lead, 8.7 mean free paths of iron, and 9.2 mean free paths of laminated shielding. ; A
C. L. Kusik; T. R. Jaworowski; D. C. Morse; D. G. Strawson
Structural response of nuclear containment shield buildings with unanticipated construction openings
NASA Astrophysics Data System (ADS)
As Nuclear Power Plants age many require steam generator replacement. There is a nickel alloy in the steam generator tubes that is susceptible to stress cracking and although these cracks can be sealed the generator becomes uneconomical without 10%-15% of the tubes. The steam generator in a typical nuclear power plant is housed in the containment structure next to the reactor. The equipment hatch is not big enough to facilitate steam generator replacement, thus construction openings in the dome of the containment structure are required. To date the structural consequences of construction openings in the dome have not been examined. This thesis examines the effects of such openings. The prototype concrete dome is made up of a 2 ft thick dome atop 3 ft thick and 170 ft high cylindrical walls (radius 65.5 ft) with a tension ring 15 ft high and 8 ft thick in between. The dome of the building is cast in two layers; a lower 9 inch layer that serves as the formwork for an upper 15 inch layer. The weight of the dome is carried in axial compression along the hoops and meridians of the dome. The first finite element model uses shell elements and considers two limiting load cases; where the two layers act as one, and where the lower layer carries the weight of both. The openings interrupt the hoops and meridians and the weight of the dome must be redistributed around the openings. Without openings, the stresses due to dead load in the structure are very low when compared to the material strength. The impact of the openings is increased compression stresses near the opening. The maximum stresses are approximately four times larger than in the original structure. These results are confirmed by the second model which is made from layers of solid elements. This model shows a significant difference between the compression on the top surface of the dome, in the affected areas, and that on the bottom surface, leading to shear stresses. These shear stresses are largest around the opening but are not large enough to cause delamination.
Mac Namara, Sinead Caitriona
The Impact of Structural Shielding on the Performance of Wireless Systems in a Single-Floor Office Building
Cochannel interference in indoor wireless communication systems can severely limit system capacity and performance. To reduce cochannel interference in indoor environments, electromagnetic shielding can be used to increase the radio isolation between physically adjacent systems. In this paper, the impact of structural (wall) shielding on the system performance of an interference-limited CDMA system is examined using a ray-tracing propagation model.
Derek C. K. Lee; Michael J. Neve; Kevin W. Sowerby
Thermodynamic modelling of Sol Hamed serpentinite, South Eastern Desert of Egypt: implication for two serpentinization stages in the Arabian-Nubian Shield ophiolites
NASA Astrophysics Data System (ADS)
The Arabian-Nubian Shield is the largest tract of juvenile continental crust of Neoproterozoic age on Earth. This crust was generated due to arc-arc collision associated with the closing of the Mozambique Ocean. Distribution of ophiolitic rocks marks fossils suture zones in the shield. Petrological, mineral chemistry, whole-rock chemistry and thermodynamic studies are carried out to examine the serpentinite component of Sol Hamed ophiolite in south Eastern Desert of Egypt. The protolith mantle was harzburgite and formed in subduction zone of forearc setting. Serpentinization occurred in two stages. The first by intrusion of high concentrated CO2 fluid released from carbonate-bearing sediments and altered basalt at the subduction zone. The serpentinization achieved during isobaric cooling path at pressure of 1 kbar and before the emplacement. The minimum temperature limit of the serpentinization is above the breakdown of lizardite to antigorite and brucite (170 �C). The fluid composition during the isobaric cooling path was buffered by the metamorphic reactions. The second stage of serpentinization took place through prograde path which led to formation of chrysotile after lizardite. The increasing in the pressure during this stage occurred as a result of extensive duplex array and thrusting of oceanic crust. The crust in the forearc basin was overloaded by 28 km of obducted and thrusted oceanic crust from both mid-oceanic and forearc basins, respectively.
Abu-Alam, T.; Hamdy, M.
The immature stages and shelter building behavior of Falgo Jeconia Ombra Evans, 1955 in eastern Ecuador (Lepidoptera: Hesperiidae: Hesperiinae).
We describe the immature stages and shelter building behavior of Falga jeconia ombra Evans, 1955 from eastern Ecuador. Chusquea scandens (Poaceae, Bambusoidea) is the larval food plant. Larvae in all stadia build shelters and forcibly eject frass with the aid of an anal comb. Later instars possess an eversible prothoracic "neck" gland. Larvae are associated with moving water. PMID:19613872
Greeney, Harold F; Warren, Andrew D
The Immature Stages and Shelter Building Behavior of Falgo Jeconia Ombra Evans, 1955 in eastern Ecuador (Lepidoptera: Hesperiidae: Hesperiinae)
We describe the immature stages and shelter building behavior of Falga jeconia ombra Evans, 1955 from eastern Ecuador. Chusquea scandens (Poaceae, Bambusoidea) is the larval food plant. Larvae in all stadia build shelters and forcibly eject frass with the aid of an anal comb. Later instars possess an eversible prothoracic �neck� gland. Larvae are associated with moving water.
Greeney, Harold F.; Warren, Andrew D.
Military Review: Desert Shield/Desert Storm.
National Technical Information Service (NTIS)
CONTENTS: CASCOM Support for DESERT SHIELD/DESERT STORM; Total Army CSS: Providing the Means for Victory; Logistics Automation Support for Desert Storm; Building the DESERT Logistics force; Depot operations Supporting DESERT SHIELD; The Readiness Group's ...
Early Stage Design Decisions: The Way to Achieve Sustainable Buildings at Lower Costs
The construction industry attempts to produce buildings with as lower environmental impact as possible. However, construction activities still greatly affect environment; therefore, it is necessary to consider a sustainable project approach based on its performance. Sustainability is an important issue to consider in design, not only due to environmental concerns but also due to economic and social matters, promoting architectural quality and economic advantages. This paper aims to identify the phases through which a design project should be developed, emphasising the importance and ability of earlier stages to influence sustainability, performance, and life cycle cost. Then, a selection of sustainability key indicators, able to be used at the design conceptual phase and able to start predicting environmental sustainability performance of buildings is presented. The output of this paper aimed to enable designers to compare and evaluate the consequences of different design solutions, based on preliminary data, and facilitate the collaboration between stakeholders and clients and eventually yield a sustainable and high performance building throughout its life cycle.
Braganca, Luis; Vieira, Susana M.; Andrade, Joana B.
Early stage design decisions: the way to achieve sustainable buildings at lower costs.
The construction industry attempts to produce buildings with as lower environmental impact as possible. However, construction activities still greatly affect environment; therefore, it is necessary to consider a sustainable project approach based on its performance. Sustainability is an important issue to consider in design, not only due to environmental concerns but also due to economic and social matters, promoting architectural quality and economic advantages. This paper aims to identify the phases through which a design project should be developed, emphasising the importance and ability of earlier stages to influence sustainability, performance, and life cycle cost. Then, a selection of sustainability key indicators, able to be used at the design conceptual phase and able to start predicting environmental sustainability performance of buildings is presented. The output of this paper aimed to enable designers to compare and evaluate the consequences of different design solutions, based on preliminary data, and facilitate the collaboration between stakeholders and clients and eventually yield a sustainable and high performance building throughout its life cycle. PMID:24578630
Bragan�a, Lu�s; Vieira, Susana M; Andrade, Joana B
Determination of lead equivalent thickness to building blocks used in shielding of diagnostic x-ray rooms in Syria.
National Technical Information Service (NTIS)
Lead equivalent thicknesses of various kinds of blocks (Hollow core, solid, filled, roof) with different thicknesses were determined. These blocks are widely used for building the diagnostic X-rya departments in Syria. Different applied voltages at X-ray ...
A. Kawash M. Khedr K. Wannus J. Souliman M. Al-Oudat
The shield-backed bug, Pachycoris stallii: Description of immature stages, effect of maternal care on nymphs, and notes on life history
The life history of the shield-backed bug, Pachycoris stallii Uhler (Heteroptera: Scutelleridae), immatures was studied on its host plant, Croton californicus Muell.-Arg. (Euphorbiaceae), in Baja California Sur, Mexico. Immature stages are described and illustrated. Pachycoris stallii is bi- or multivoltine and occurs in xeric areas with sandy soil where it is rarely encountered away from C. californicus. Nymphs and adults feed on seeds within C. californicus fruit. Bugs oviposit on the underside of leaves, and females guard their eggs and first-instar nymphs from natural enemies. Embryonic orientation of prolarvae is nonrandom; each embryo is oriented with its venter directed toward the ground. This orientation may facilitate aggregation of first instars. The longitudinal axes of eggs are always oriented upward at about a 16� angle of deviation from a line perpendicular to the leaf surface. This is the first recorded observation of this phenomenon in Pentatomoidea. Experimental removal of females guarding first instars results in 100% loss of nymphs, and this is attributed to disruption of the aggregative behavior of nymphs. Maternal guarding appears to be a net benefit to P. stallii, despite possible costs to the brooding female.
Williams, Livy; Coscaron, Maria C; Dellape, Pablo M; Roane, Timberley M
A New Approach to Predicting the Thermal Environment in Buildings at the Early Design Stage. Building Research Establishment Current Paper 2/74.
ERIC Educational Resources Information Center
The paper argues that existing computer programs for thermal predictions do not produce suitable information for architects, particularly at the early stages of design. It reviews the important building features that determine the thermal environment and the need for heating and cooling plant. Graphical design aids are proposed, with examples to�
Milbank, N. O.
The Hanford Waste Vitrification Plant (HWVP) will produce canisters filled with high-level radioactive waste immobilized in borosilicate glass. This report discusses a Shielded Canister Transporter (SCT) which will provide the means for safe transportation and handling of the canisters from the Vitrification Building to the Canister Storage Building (CSB). The stainless steel canisters are 0.61 meters in diameter, 3.0 meters
G. G. Jr. Eidem; R. Fages
Development of a methodology for defining whole-building energy design targets for commercial buildings: Phase 2, Development concept stage report
Since 1985, the Pacific Northwest Laboratory (PNL) has managed the Whole-Building Energy Design Targets project for the US Department of Energy (DOE) Office of Building Technologies (formerly the Office of Buildings and Community Systems). The primary focus of the Targets project is to develop a flexible methodology for buildings industry use in setting energy performance guidelines for commercial buildings and for determining compliance with those guidelines. The project is being conducted as a two-phase effort. In Phase 1, Planning, the project team determined the research that was necessary for developing the Targets methodology. In the concept stage of Phase 2, Development, the team sought to define the technical and software development concepts upon which the overall Targets methodology will be based. The concept stage work is documented in four volumes, of which this summary volume is the first. The three other volumes are Volume 2: Technical Concept Development Task Reports, Volume 3: Workshop Summaries, and Volume 4: Software Concept Development Task Reports. 8 refs., 14 figs.
Jones, J.W. (American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA (USA)); Deringer, J.J. (American Inst. of Architects, Washington, DC (USA)); McKay, H.N. (Illuminating Engineering Society of North America, New York, NY (USA))
A modular system for containing projectiles has a sheet of material including at least a polycarbonate layer held by a metal frame having a straight frame member corresponding to each straight edge of the sheet. Each frame member has a U-shaped shield channel covering and holding a straight edge of the sheet and an adjacent U-shaped clamp channel rigidly held against the shield channel. A flexible gasket separates each sheet edge from its respective shield channel; and each frame member is fastened to each adjacent frame member only by clamps extending between adjacent clamp channels.
Snyder, Keith W. (Sandia Park, NM)
Shielding for the variable energy cyclotron at Calcutta
Shielding calculations are done for the AVF Cyclotron under construction at Calcutta. Concrete shields are designed to reduce the fast neutron flux to less than the maximum permissible levels outside the shields. Earth shields are designed to reduce the fast neutron flux outside the building to less than the maximum permissible levels for public exposure. Experimentally measured values of half-value
G. Muthukrishnan; H. Singh; R. Mukherjee
InterStage Feature Propagation in Cascade Building with AdaBoost
A modification of the cascaded detector with the Ada-Boost trained stage classifiers is proposed and brought to bear on the face detection problem. The cascaded detector is a sequential classifier with the ability of early rejection of easy samples. Each decision in the sequence is made by a separately trained classifier, a stage classifier. In proposed modification the features from
Jan Sochman; Jiri Matas
Visualizing the Shields Parameter
NSDL National Science Digital Library
This is not so much an activity as it is a useful tool to build an activity around. I created an Excel spreadsheet that calculates the Shields parameter and the grain Reynolds number for a given set of conditions, then plots the resultant values on the Shields diagram. Thus, students can tweak the boundary shear stress value to calculate the stress required to move a given grain size in any fluid, under any gravitational conditions. It is a great way for them to understand how changes in fluid density and viscosity (water vs. air) affect initiation of motion, as well as the effects of grain size. I might use this in a lecture on initiation of motion, asking them to answer some basic questions (see attached example).
Hickson, Tom
SNF shipping cask shielding analysis
The Waste Management and Remedial Action Division has planned a modification sequence for storage facility 7827 in the Solid Waste Storage Area (SWSA). The modification cycle is: (1) modify an empty caisson, (2) transfer the spent nuclear fuel (SNF) of an occupied caisson to a hot cell in building 3525 for inspection and possible repackaging, and (3) return the package to the modified caisson in the SWSA. Although the SNF to be moved is in the solid form, it has different levels of activity. Thus, the following 5 shipping casks will be available for the task: the Loop Transport Carrier, the In- Pile Loop LITR HB-2 Carrier, the 6.5-inch HRLEL Carrier, the HFIR Hot Scrap Carrier, and the 10-inch ORR Experiment Removal Shield Cask. This report describes the shielding tasks for the 5 casks: determination of shielding characteristics, any streaming avenues, estimation of thermal limits, and shielding calculational uncertainty for use in the transportation plan.
Johnson, J.O.; Pace, J.V. III
Performance of solar shields. [Skylab 1 micrometeoroid shield difficulties
NASA Technical Reports Server (NTRS)
The loss of the micrometeoroid shield from the Orbital Workshop section of Skylab 1 about 63 seconds after lift-off, was the catalyst for a prodigious effort to develop a substitute for the passive portion of the thermal control system. An intensive effort is described in which numerous potential thermal shield materials were assessed, and during which period ten specific shield designs were developed and carried through various stages of development and test. Thermal shield materials data are discussed, including optical, strength, fatigue, outgassing, tackiness, ultraviolet radiation, and material memory properties. Specifically addressed are thermal shield materials selection criteria and the design, development, and test requirements associated with the successful development of Skylab thermal shields, and specifically the two thermal shields subsequently deployed over the exposed gold foil skin of the Orbital Workshop. Also considered are the general performance and thermal improvements provided by both the parasol design deployed by the Skylab 1 crew, and the sail design deployed by the Skylab 2 crew.
Schwinghamer, R. J.
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
66. CORBELS, BLIND ARCHES & SHIELDS, COMMONS EAST WALL, LOOKING EAST - Smithsonian Institution Building, 1000 Jefferson Drive, between Ninth & Twelfth Streets, Southwest, Washington, District of Columbia, DC
NASA Technical Reports Server (NTRS)
A sail like sunshade for possible use as a sunscreen for the Skylab Orbital Workshop (OWS) is shown being fabricated in the GE Building across the street from Johnson Space Center, Houston Texas. Three people help the steamstress feed the material through the sewing machine. The three-layered sunshade will be composed of a top layer of aluminized mylar, a middle layer of laminated nylon ripstop, and a bottom layer of thin nylon. Working on the sunshade are from left to right: Dale Gentry, Elizabeth Gauldin, Alyene Baker, and James H. Barnett Jr. Mrs. Baker, a GE employee, operates the double needle Singer sewing machine. Barnett is head of the Crew Equipment Development Section of JSC Crew Systems Division. Mrs. Gauldin is also with the Crew Systems Division. Gentry works for GE. The work shown here is part of the crash program underway to prepare a sunshield for Skylab to replace the orginal shield which was lost when Skylab 1 was launched on May 14, 1973. The improvised solar shield selected to be used will be carried to Earth orbit by the Skylab 2 crewman who will then deploy the reflective parasol to shade part of the OWS from the hot rays of the sun. Loss of the orginal sun shield has caused an overheating problem. in the Orbital Work Shop.
Policy Building Blocks: Helping Policymakers Determine Policy Staging for the Development of Distributed PV Markets: Preprint
There is a growing body of qualitative and a limited body of quantitative literature supporting the common assertion that policy drives development of clean energy resources. Recent work in this area indicates that the impact of policy depends on policy type, length of time in place, and economic and social contexts of implementation. This work aims to inform policymakers about the impact of different policy types and to assist in the staging of those policies to maximize individual policy effectiveness and development of the market. To do so, this paper provides a framework for policy development to support the market for distributed photovoltaic systems. Next steps include mathematical validation of the framework and development of specific policy pathways given state economic and resource contexts.
Doris, E.
Investigation of Lightning Rod Shielding Angle
NASA Astrophysics Data System (ADS)
This paper studies those parameters affecting the shielding angle of the lightning rod (Franklin Rod) above very tall buildings. It was recommended that the shielding angle of the lightning rod is about 45�?60�. The downward lightning leader is modeled by using discrete line charges to consider the exponential distribution of charges through the downward leader. The voltage condition used by Rizk is used to investigate the inception of the upward lightning leader. Different air conditions (relative air density and air humidity) are considered for more practical simulation. The influences of lightning parameters and lightning rod height on the shielding angle are studied. The results shows that, lightning leader parameters, lightning rod height and ground slope have series effects on the lightning rod shielding angle. Based on the results, a lightning rod shielding angle for shielding design is recommended to decrease the lightning stroke to the lightning rod.
Nayel, Mohamed
A shield for restricting molten corium from flowing into a water sump disposed in a floor of a containment vessel includes upper and lower walls which extend vertically upwardly and downwardly from the floor for laterally bounding the sump. The upper wall includes a plurality of laterally spaced apart flow channels extending horizontally therethrough, with each channel having a bottom disposed coextensively with the floor for channeling water therefrom into the sump. Each channel has a height and a length predeterminedly selected for allowing heat from the molten corium to dissipate through the upper and lower walls as it flows therethrough for solidifying the molten corium therein to prevent accumulation thereof in the sump.
McDonald, Douglas B. (Pleasanton, CA); Buchholz, Carol E. (San Jose, CA)
Rootless shields grow both in breadth and height through the accumulation of repeated overflows from the summits of the shields. In this photo, a stream of lava is flowing southward down the flank of this emergent shield....
Advanced Multifunctional MMOD Shield: Radiation Shielding Assessment
NASA Technical Reports Server (NTRS)
Deep space missions must contend with a harsh radiation environment Impacts to crew and electronics. Need to invest in multifunctionality for spacecraft optimization. MMOD shield. Goals: Increase radiation mitigation potential. Retain overall MMOD shielding performance.
Rojdev, Kristina; Christiansen, Eric
Advanced Multifunctional MMOD Shield: Radiation Shielding Assessment
NASA Technical Reports Server (NTRS)
As NASA is looking to explore further into deep space, multifunctional materials are a necessity for decreasing complexity and mass. One area where multifunctional materials could be extremely beneficial is in the micrometeoroid orbital debris (MMOD) shield. A typical MMOD shield on the International Space Station (ISS) is a stuffed whipple shield consisting of multiple layers. One of those layers is the thermal blanket, or multi-layer insulation (MLI). By increasing the MMOD effectiveness of MLI blankets, while still preserving their thermal capabilities, could allow for a less massive MMOD shield. Thus, a study was conducted to evaluate concept MLI blankets for MMOD shields. In conjunction, these MLI blankets and the subsequent MMOD shields were also evaluated for their radiation shielding effectiveness towards protecting crew. These concepts were evaluated against the ISS MLI blankets and the ISS MMOD shield, which acted as the baseline. These radiation shielding assessments were performed using the high charge and energy transport software (HZETRN). This software is based on a one-dimensional formula of the Boltzmann transport equation with a straight-ahead approximation. Each configuration was evaluated against the following environments to provide a diverse view of radiation shielding effectiveness in most space environments within the heliosphere: August 1972 solar particle event, October 1989 solar particle event, 1982 galactic cosmic ray environment (during solar maximum), 1987 galactic cosmic ray environment (during solar minimum), and a low earth orbit environment in 1970 that corresponded to an altitude of 400 km and inclination of 51.6 . Both the absorbed dose and the dose equivalent were analyzed, but the focus of the discussion was on the dose equivalent since the data is most concerned with radiation shielding of the crew. The following paper outlines the evaluations performed and discusses the results and conclusions of this evaluation for radiation shielding effectiveness. Future work will focus on optimizing the radiation shielding properties for the MMOD shield. Submission
Rojdev, Kristina; Christiansen, Eric
Modeling and Simulation of the ARES UPPER STAGE Transportation, Lifting, Stacking and Mating Operations Within the Vehicle Assembly Building at KSC
NASA Technical Reports Server (NTRS)
This viewgraph presentation describes the modeling and simulation of the Ares Upper Stage Transportation, lifting, stacking, and mating operations within the Vehicle Assembly Building (VAB) at Kennedy Space Center (KSC). An aerial view of KSC Launch Shuttle Complex, two views of the Delmia process control layout, and an upper stage move subroutine and breakdown are shown. An overhead image of the VAB and the turning basin along with the Pegasus barge at the turning basin are also shown. This viewgraph presentation also shows the actual design and the removal of the mid-section spring tensioners, the removal of the AFT rear and forward tensioners tie downs, and removing the AFT hold down post and mount. US leaving the Pegasus Barge, the upper stage arriving at transfer aisle, upper stage receiving/inspection in transfer aisle, and an overhead view of upper stage receiving/inspection in transfer aisle are depicted. Five views of the actual connection of the cabling to the upper stage aft lifting hardware are shown. The upper stage transporter forward connector, two views of the rotation horizontal to vertical, the disconnection of the rear bolt ring cabling, the lowering of the upper stage to the inspection stand, disconnection of the rear bolt ring from the upper stage, the lifting of the upper stage and inspection of AFT fange, and the transfer of upper stage in an integrated stack are shown. Six views of the mating of the upper stage to the first stage are depicted. The preparation, inspection, and removal of the forward dome are shown. The upper stage mated on the integrated stack and crawler is also shown. This presentation concludes with A Rapid Upper Limb Assessment (RULA) utilizing male and female models for assessing risk factors to the upper extremities of human beings in an actual physical environment.
Kromis, Phillip A.
Design and performances of a shielded liquid helium insert with an optically heated variable temperature stage for the study of low frequency magnetic noise in HT_c superconductors
NASA Astrophysics Data System (ADS)
We have designed and built a liquid helium immersion insert which is magnetically shielded from the ambient magnetic field fluctuations by the use of a superconducting lead can. The insert has a variable temperature stage made of sapphire which is optically heated by the light guided from an external lamp via a glass rod. The temperature regulation is achieved by the use of a commercial PID controller: the temperature of the sapphire ranges from 50 K to 100 K with peak to peak fluctuations less than 20 mK over a 3 minutes observation period. The magnetic noise inside the insert has been measured with a low T_c dc-SQUID and the white noise level above 200 Hz is less than 4 fT/sqrtHz. Furthermore, the magnetic attenuation factor due to the superconducting lead can is greater than 26 500 for frequencies above 15 Hz. This cryogenic insert is used for studying low frequency vortex noise in high T_c superconducting thin films at different temperatures and the field penetration in the films as a function of the applied magnetic field during its transition state.
Ridereau, X.; Sing, M. Lam Chok; Bloyet, D.
NASA Technical Reports Server (NTRS)
This report provides innovative, low-weight shielding solutions for spacecraft and the ballistic limit equations that define the shield's performance in the meteoroid/debris environment. Analyses and hypervelocity impact testing results are described that have been used in developing the shields and equations. Spacecraft shielding design and operational practices described in this report are used to provide effective spacecraft protection from meteoroid and debris impacts. Specific shield applications for the International Space Station (ISS), Space Shuttle Orbiter and the CONTOUR (Comet Nucleus Tour) space probe are provided. Whipple, Multi-Shock and Stuffed Whipple shield applications are described.
Christiansen, Eric L.
National Technical Information Service (NTIS)
Precise quantities of lubricant under automatic control are injected through chambers of housings into shielded rolling element bearings. Separate feed line conduits directly deliver the lubricant to the shielded critical surfaces of such bearings and ins...
J. A. Wong T. L. Daugherty G. D. Huntzberry
Development of a methodology for defining whole-building energy design targets for commercial buildings: Phase 2, Development Concept Stage Report
This report documents eight tasks performed as part of the Whole-Building Energy Design Targets project, in which detailed conceptual approaches were produced for each element of the proposed Targets model. The eight task reports together describe the important modules proposed for inclusion in the Targets model: input module, energy module, characteristic development moduel, building cost module, analysis control module, energy cost module, search routines module, and economic analysis module. 16 refs., 16 figs., 5 tabs.
McKay, H.N. (Illuminating Engineering Society of North America, New York, NY (USA)); Deringer, J.J. (American Inst. of Architects, Washington, DC (USA)); Jones, J.W. (American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA (USA)); Hall, J.D. (Deringer Group, Riva, MD (USA))
Rotating shielded crane system
A rotating, radiation shielded crane system for use in a high radiation test cell, comprises a radiation shielding wall, a cylindrical ceiling made of radiation shielding material and a rotatable crane disposed above the ceiling. The ceiling rests on an annular ledge intergrally attached to the inner surface of the shielding wall. Removable plugs in the ceiling provide access for the crane from the top of the ceiling into the test cell. A seal is provided at the interface between the inner surface of the shielding wall and the ceiling.
Commander, John C. (Idaho Falls, ID)
Eruption history of the Tharsis shield volcanoes, Mars
The Tharsis Montes volcanoes and Olympus Mons are giant shield volcanoes. Although estimates of their average surface age have been made using crater counts, the length of time required to build the shields has not been considered. Crater counts for the volcanoes indicate the constructs are young; average ages are Amazonian to Hesperian. In relative terms; Arsia Mons is the
J. B. Plescia
SOUTHWEST REAR AND SOUTHEAST SIDE. Protective berm at left shields ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
SOUTHWEST REAR AND SOUTHEAST SIDE. Protective berm at left shields Air Supply building from launch pad - Edwards Air Force Base, South Base Sled Track, Air Supply Building for Building No. 0545, South of Sled Track at east end, Lancaster, Los Angeles County, CA
Flow-By-Flow Mapping on Fogo, Cape Verde Islands, Reveals Long Term Variations in Eruption Distributions and Volcanic Edifice Structure at a Shield-Stage Oceanic Island Volcano
NASA Astrophysics Data System (ADS)
Most maps of large oceanic island shield volcanoes show the lava flows and scoria cones of individual historic and subhistoric eruptions as individual units but then resort to grouping older rocks into larger stratigraphic units. This grouping makes it difficult to characterize long-term progressive trends in volumes of individual eruptions and distributions of eruptive vents, but is commonly made necessary by poor exposure, limited compositional variation between individual eruptions, and burial of older by younger volcanic rocks. In contrast, work on Fogo, Cape Verde Islands has involved flow-by-flow mapping of rocks erupted over an extended period of tens of thousands of years, as part of the process of mapping the island and producing a 1:25 000 scale geological map for research and hazard management purposes. Around three-quarters of the island is characterized by low rainfall and limited vegetation cover, with erosion restricted to narrow gullies. Only in small areas on the windward side of the island do higher rainfall, thick vegetation and deeper erosion combine to prevent flow-by-flow mapping. The map of the island is accompanied by a rigorous representation of direct and inferred age relationships between lavas and scoria cones of different eruptions using a novel type of age correlation diagram. The time period covered by the flow-by-flow mapping includes both the final stages of growth of an older shield volcano (Monte Amarelo volcano) prior to its collapse and the subsequent growth of a new volcano (Cha das Caldeiras volcano). The latter forms a thick infill and summit cone within the Monte Amarelo collapse scar together with partial covering of the outer flanks of the Monte Amarelo volcano with a veneer of younger lavas and scoria cones. The erupted rocks are compositionally varied (ankaramitic nephelinites, basanites, tephrites) and often highly porphyritic. Petrographic criteria were therefore used to aid field mapping, define lithostratigraphic units and demonstrate systematic changes in compositions of erupted magmas through time. Some of these changes, particularly eruptions of ankaramitic magmas, coincide with similar sequences of volcano-structural changes that have occurred prior to the Monte Amarelo collapse and again during the Holocene (beginning around 11 000 years before present; Foeken et al, 2009). The flow-by-flow mapping approach has allowed reconstruction and comparison of the sequences of these structural changes, and thus provides insights into the inferred progressive destabilization of the eastern flank of Fogo during the Holocene, as well as into wide variations in eruption and resurfacing rates that have occurred on decade to century timescales in more recent times. Foeken, J.P.T., Day, S.J. & Stuart, F.M. (2009) Cosmogenic 3He exposure dating of the Quaternary basalts from Fogo, Cape Verdes: Implications for rift zone and magmatic reorganization. Quaternary Geology 4 (2009) 37 - 49.
Day, S. J.
IET distant contextual view of entrance to shielded roadway. facing ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
IET distant contextual view of entrance to shielded roadway. facing west. stack and other buildings have been removed. INEEL negative no. HD-21-7-2 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
INTOR radiation shielding for personnel access
The INTOR reactor shield system consists of the blanket, bulk shield, penetration shield, component shield, and biological shield. The bulk shield consists of two parts: (a) the inboard shield; and (b) the outboard shield. The distinction between the different components of the shield system is essential to satisfy the different design constraints and achieve various objectives.
Gohar, Y.; Abdou, M.
NASA Technical Reports Server (NTRS)
Gap, where cable joins connector housing, is shielded effectively by composite RF shielding made from suitable potting resin material (fumed silica, thixotropic prepolymer composition), conductive coating (silver-filled, flexible, polyurethane resin), and protective jacket (wax coated housing formed around another wax form having contours shaped to match configuration).
Fisher, A.; Clatterbuck, C.
Iron shielded MRI optimization
The design of the main current systems of an actively shielded and of an iron shielded MRI device for nuclear resonance imaging, is considered. The model for the analysis of the magnetic induction produced by the current system, is based on the combination of a Boundary Element technique and of the integration of two Fredholm integral equations of the first
C. A. Borghi; M. Fabbri
A gamma ray detector shield comprised of a rigid, lead, cylindrical-shaped vessel having upper and lower portions with an pneumatically driven, sliding top assembly. Disposed inside the lead shield is a gamma ray scintillation crystal detector. Access to the gamma detector is through the sliding top assembly.
Ohlinger, R.D.; Humphrey, H.W.
EMP Instrumentation Shielding and Evaluation.
National Technical Information Service (NTIS)
Special purpose hardware was developed to harden recording instrumentation to EMP simulator fields. This included probe shields, instrumentation system shields, and differential voltage attenuators. Calibration and shielding evaluation techniques were als...
B. C. Tupper
Setting the Stage with Geometry: Lessons & Worksheets to Build Skills in Measuring Perimeter, Area, Surface Area, and Volume. Poster/Teaching Guide. Expect the Unexpected with Math[R
ERIC Educational Resources Information Center
"Setting the Stage with Geometry" is a new math program aligned with the National Council of Teachers of Mathematics (NCTM) standards that is designed to help students in grades 6-8 build and reinforce basic geometry skills for measuring 2D and 3D shapes. Developed by The Actuarial Foundation, this program seeks to provide skill-building math�
Actuarial Foundation, 2013
The Transtheoretical Stages of Change Model and Motivational Interviewing for Building Maternal Supportiveness in Cases of Sexual Abuse.
ERIC Educational Resources Information Center
Describes use of the Stages of Change Model and Motivational Interviewing to enhance supportiveness of mothers in child intra-familial sexual abuse. Research indicates many mothers are ambivalent and vary in their levels of support; however, the crucial impact of maternal support on child adjustment and recovery has been emphasized. Further study�
Corcoran, Jacqueline
Building fast well-balanced two-stage numerical schemes for a model of two-phase flows
NASA Astrophysics Data System (ADS)
We present a set of well-balanced two-stage schemes for an isentropic model of two-phase flows arisen from the modeling of deflagration-to-detonation transition in granular materials. The first stage is to absorb the source term in nonconservative form into equilibria. Then in the second stage, these equilibria will be composed into a numerical flux formed by using a convex combination of the numerical flux of a stable Lax-Friedrichs-type scheme and the one of a higher-order Richtmyer-type scheme. Numerical schemes constructed in such a way are expected to get the interesting property: they are fast and stable. Tests show that the method works out until the parameter takes on the value CFL, and so any value of the parameter between zero and this value is expected to work as well. All the schemes in this family are shown to capture stationary waves and preserves the positivity of the volume fractions. The special values of the parameter 0,1/2,1/(1+CFL), and CFL in this family define the Lax-Friedrichs-type, FAST1, FAST2, and FAST3 schemes, respectively. These schemes are shown to give a desirable accuracy. The errors and the CPU time of these schemes and the Roe-type scheme are calculated and compared. The constructed schemes are shown to be well-balanced and faster than the Roe-type scheme.
Thanh, Mai Duc
Evolution of Hawaiian shield volcano revealed by antecryst-hosted melt inclusions
NASA Astrophysics Data System (ADS)
Ocean island basalts, exemplified by the Hawaiian Volcanics, are often considered to be the best targets for understanding the chemical and thermal structure of upwelling mantle plumes. The important feature with regards to the petrogenesis of the recent Hawaiian shield building lavas is the existence of a double volcanic loci (Loa and Kea), which has resulted in large-scale heterogeneity between the north-western and south-eastern sides of the plume. The temporal Sr-Nd-Hf-Pb isotopic trends displayed by the Loa-type lavas may have been caused by systematic vertical heterogeneity of the SW part of the Hawaiian plume. The majority of the available OIB samples are limited to the youngest lava flows covering the shield, with the exception of samples obtained from drilled cores and land slide deposits. Thus, sampling is biased to the latest stages of the shield building process, and consequently, so are geochemical studies. We found that the majority of olivine crystals coarser than �1 mm in the Hawaiian lavas are antecryst, which originally crystallized from previous stages of Hawaiian magmatism. These anatecrysts were then plastically deformed prior to entrainment in the erupted host magmas. The Pb isotopic compositions of antecryst-hosted melt inclusions reveal that the mantle source components that formed Hawaiian shields successively changed during shield formation. The temporal geochemical trend in the Kilauea melt inclusion could be caused by increasing the degree of partial melting by moving the melting source of the volcano from the periphery to the centre of the plume. The Pb isotopic trend of Koolau melt inclusions are consistent with the previously identified temporal isotopic trend, which shows that the 207Pb/206Pb and 208Pb/206Pb of the Koolau magma systematically increased with time. Thus, antecryst-hosted melt inclusions preserve geochemical information regarding the petrogenesis of the Hawaiian shield lavas, which is unobtainable via whole rock geochemical studies. These observations also demonstrate that a significant fraction of olivine antecrysts are derived from dunite or harzburgite channels/cumulates that were formed by dissolution and/or crystallization processes during previous magmatic events. Thus, the entrainment of inherited mantle-derived crystallization products by younger batches of magma is a common phenomenon in the Hawaiian magma plumbing system.
Tanaka, R.; Sakyi, P. A.; Kobayashi, K.; Nakamura, E.
Kerry Lee, NASA Orion radiation system manager, explains how radiation shielding is used to block harmful particles coming into the spacecraft without producing secondary particles that can cause e...
Grounding, Shielding, and Bonding.
National Technical Information Service (NTIS)
In the electromagnetic compatibility design (EMC) of systems and circuits, both grounding and shielding are related to the coupling mechanisms of the system with (radiated) electromagnetic fields. Grounding is more related to the source or victim circuit ...
J. Catrysse
An efficient device for capturing fast moving particles has an adhesive particle shield that includes (i) a mounting panel and (ii) a film that is attached to the mounting panel wherein the outer surface of the film has an adhesive coating disposed thereon to capture particles contacting the outer surface. The shield can be employed to maintain a substantially particle free environment such as in photolithographic systems having critical surfaces, such as wafers, masks, and optics and in the tools used to make these components, that are sensitive to particle contamination. The shield can be portable to be positioned in hard-to-reach areas of a photolithography machine. The adhesive particle shield can incorporate cooling means to attract particles via the thermophoresis effect.
Klebanoff, Leonard Elliott (Dublin, CA); Rader, Daniel John (Albuquerque, NM); Walton, Christopher (Berkeley, CA); Folta, James (Livermore, CA)
NASA Technical Reports Server (NTRS)
Impact-resistant shield designed to consist of aluminum honeycomb structure sandwiched between inner and outer aluminum skins. Intended to protect radioisotope thermoelectric generator of spacecraft from impact with ground or water after free fall from upper atmosphere. Designed to absorb impact energy by buckling, while inner and outer skins designed to protect against shrapnel, overpressure, and impact loads. Concept of shield applicable to crashproof compartments for ground vehicles and aircraft.
Bixler, Charles H.
NASA Technical Reports Server (NTRS)
This paper describes International Space Station (ISS) shielding for micrometeoroid orbital debris (MMOD) protection, requirements for protection, and the technical approach to meeting requirements. Current activities in MMOD protection for ISS will be described, including efforts to augment MMOD protection by adding shields on-orbit. Observed MMOD impacts on ISS elements such as radiators, modules and returned hardware will be described. Comparisons of the observed damage with predicted damage using risk assessment software will be made.
Christiansen, Eric
NASA Technical Reports Server (NTRS)
Method employs curved shield on each side of mining machine. In stowed position, shield folded against roof-support columns on one side. In deployed position, shield raised and braced against coal-seam wall by hydraulic cylinder. Shield supports wall until roof and wall properly secured by bolting and cement coating.
Lewis, E. V.
Grounding and shielding in the accelerator environment
Everyday features of the accelerator environment include long cable runs, high power and low level equipment sharing building space, stray electromagnetic fields and ground voltage differences between the sending and receiving ends of an installation. This paper pictures some Fermilab installations chosen to highlight significant features and presents practices, test methods and equipment that have been helpful in achieving successful shielding. Throughout the report are numbered statements aimed at summarizing good practices and avoiding pitfalls.
Kerns, Q.
Honeycomb thermal shield study
NASA Technical Reports Server (NTRS)
A honeycomb thermal shield is described which is an economical and reliable alternative to existing thermal shielding methods for reducing the radiated heat loss from elements which will not allow obstructions in the field of view. The device is simply open-face honeycomb of the type used throughout the aerospace industry for structural panels. The honeycomb thermal shield uses only the core of the honeycomb panel, so it has little structural stiffness and is transparent through the cells. It is located in close proximity to, but conductively decoupled from, the element to be shielded (the radiative source) with the axis of the honeycomb cells parallel to the view direction of the source. The source radiates into a 2pi steradian field occupied by the shield. The view field will be transparent along the axis of the honeycomb but will be increasingly obscured as the off-normal view angle increases. The angular dependence is a function of the cell height to width ratio.
Dombroski, R. M.
NASA Technical Reports Server (NTRS)
WAKE SHIELD FACILITY FREE FLYER MATE TO CANISTER KSC-96PC-2961.10 In NASA's Building AE on Cape Canaveral Air Station, the Wake Shield Facility-3 (WSF- 3) free-flyer is being mated to the carrier to complete the payload. The WSF-3 is one of two primary payloads on Space Shuttle Mission STS-80. The Shuttle Columbia is being prepared for liftoff on the final Shuttle flight of 1996 around Nov. 8 from Launch Pad 39B.
NASA Technical Reports Server (NTRS)
WAKE SHIELD FACILITY FREE FLYER MATE TO CANISTER KSC-96PC-2961.8 In NASA's Building AE on Cape Canaveral Air Station, the Wake Shield Facility-3 (WSF- 3) free-flyer is being mated to the carrier to complete the payload. The WSF-3 is one of two primary payloads on Space Shuttle Mission STS-80. The Shuttle Columbia is being prepared for liftoff on the final Shuttle flight of 1996 around Nov. 8 from Launch Pad 39B.
NASA Technical Reports Server (NTRS)
WAKE SHIELD FACILITY FREE FLYER MATE TO CANISTER KSC-96PC-2961.5 In NASA's Building AE on Cape Canaveral Air Station, the Wake Shield Facility-3 (WSF- 3) free-flyer is being mated to the carrier to complete the payload. The WSF-3 is one of two primary payloads on Space Shuttle Mission STS-80. The Shuttle Columbia is being prepared for liftoff on the final Shuttle flight of 1996 around Nov. 8 from Launch Pad 39B.
Dynamic rotating-shield brachytherapy
Purpose: To present dynamic rotating shield brachytherapy (D-RSBT), a novel form of high-dose-rate brachytherapy (HDR-BT) with electronic brachytherapy source, where the radiation shield is capable of changing emission angles during the radiation delivery process.Methods: A D-RSBT system uses two layers of independently rotating tungsten alloy shields, each with a 180� azimuthal emission angle. The D-RSBT planning is separated into two stages: anchor plan optimization and optimal sequencing. In the anchor plan optimization, anchor plans are generated by maximizing the D{sub 90} for the high-risk clinical-tumor-volume (HR-CTV) assuming a fixed azimuthal emission angle of 11.25�. In the optimal sequencing, treatment plans that most closely approximate the anchor plans under the delivery-time constraint will be efficiently computed. Treatment plans for five cervical cancer patients were generated for D-RSBT, single-shield RSBT (S-RSBT), and {sup 192}Ir-based intracavitary brachytherapy with supplementary interstitial brachytherapy (IS + ICBT) assuming five treatment fractions. External beam radiotherapy doses of 45 Gy in 25 fractions of 1.8 Gy each were accounted for. The high-risk clinical target volume (HR-CTV) doses were escalated such that the D{sub 2cc} of the rectum, sigmoid colon, or bladder reached its tolerance equivalent dose in 2 Gy fractions (EQD2 with ?/?= 3 Gy) of 75 Gy, 75 Gy, or 90 Gy, respectively.Results: For the patients considered, IS + ICBT had an average total dwell time of 5.7 minutes/fraction (min/fx) assuming a 10 Ci{sup 192}Ir source, and the average HR-CTV D{sub 90} was 78.9 Gy. In order to match the HR-CTV D{sub 90} of IS + ICBT, D-RSBT required an average of 10.1 min/fx more delivery time, and S-RSBT required 6.7 min/fx more. If an additional 20 min/fx of delivery time is allowed beyond that of the IS + ICBT case, D-RSBT and S-RSBT increased the HR-CTV D{sub 90} above IS + ICBT by an average of 16.3 Gy and 9.1 Gy, respectively.Conclusions: For cervical cancer patients, D-RSBT can boost HR-CTV D{sub 90} over IS + ICBT and S-RSBT without violating the tolerance doses to the bladder, rectum, or sigmoid. The D{sub 90} improvements from D-RSBT depend on the patient, the delivery time budget, and the applicator structure.
Liu, Yunlong [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 (United States)] [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 (United States); Flynn, Ryan T.; Kim, Yusung [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)] [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States); Yang, Wenjun [Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin 53705 (United States)] [Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin 53705 (United States); Wu, Xiaodong [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 and Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)] [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 and Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)
Radiation shielding composition
A composition for use as a radiation shield. The shield is a concrete product containing a stable uranium aggregate for attenuating gamma rays and a neutron absorbing component, the uranium aggregate and neutron absorbing component being present in the concrete product in sufficient amounts to provide a concrete having a density between about 4 and about 15 grams/cm.sup.3 and which will at a predetermined thickness, attenuate gamma rays and absorb neutrons from a radioactive material of projected gamma ray and neutron emissions over a determined time period. The composition is preferably in the form of a container for storing radioactive materials that emit gamma rays and neutrons. The concrete container preferably comprises a metal liner and/or a metal outer shell. The resulting radiation shielding container has the potential of being structurally sound, stable over a long period of time, and, if desired, readily mobile.
Quapp, William J. (Idaho Falls, ID); Lessing, Paul A. (Idaho Falls, ID)
Radiation shielding composition
A composition for use as a radiation shield. The shield is a concrete product containing a stable uranium aggregate for attenuating gamma rays and a neutron absorbing component, the uranium aggregate and neutron absorbing component being present in the concrete product in sufficient amounts to provide a concrete having a density between about 4 and about 15 grams/cm.sup.3 and which will at a predetermined thickness, attenuate gamma rays and absorb neutrons from a radioactive material of projected gamma ray and neutron emissions over a determined time period. The composition is preferably in the form of a container for storing radioactive materials that emit gamma rays and neutrons. The concrete container preferably comprises a metal liner and/or a metal outer shell. The resulting radiation shielding container has the potential of being structurally sound, stable over a long period of time, and, if desired, readily mobile.
Quapp, William J. (Idaho Falls, ID); Lessing, Paul A. (Idaho Falls, ID)
Radiation shielding composition
A composition is disclosed for use as a radiation shield. The shield is a concrete product containing a stable uranium aggregate for attenuating gamma rays and a neutron absorbing component, the uranium aggregate and neutron absorbing component being present in the concrete product in sufficient amounts to provide a concrete having a density between about 4 and about 15 grams/cm{sup 3} and which will at a predetermined thickness, attenuate gamma rays and absorb neutrons from a radioactive material of projected gamma ray and neutron emissions over a determined time period. The composition is preferably in the form of a container for storing radioactive materials that emit gamma rays and neutrons. The concrete container preferably comprises a metal liner and/or a metal outer shell. The resulting radiation shielding container has the potential of being structurally sound, stable over a long period of time, and, if desired, readily mobile. 5 figs.
Quapp, W.J.; Lessing, P.A.
The Waste Treatment Building System provides the space, layout, structures, and embedded subsystems that support the processing of low-level liquid and solid radioactive waste generated within the Monitored Geologic Repository (MGR). The activities conducted in the Waste Treatment Building include sorting, volume reduction, and packaging of dry waste, and collecting, processing, solidification, and packaging of liquid waste. The Waste Treatment Building System is located on the surface within the protected area of the MGR. The Waste Treatment Building System helps maintain a suitable environment for the waste processing and protects the systems within the Waste Treatment Building (WTB) from most of the natural and induced environments. The WTB also confines contaminants and provides radiological protection to personnel. In addition to the waste processing operations, the Waste Treatment Building System provides space and layout for staging of packaged waste for shipment, industrial and radiological safety systems, control and monitoring of operations, safeguards and security systems, and fire protection, ventilation and utilities systems. The Waste Treatment Building System also provides the required space and layout for maintenance activities, tool storage, and administrative facilities. The Waste Treatment Building System integrates waste processing systems within its protective structure to support the throughput rates established for the MGR. The Waste Treatment Building System also provides shielding, layout, and other design features to help limit personnel radiation exposures to levels which are as low as is reasonably achievable (ALARA). The Waste Treatment Building System interfaces with the Site Generated Radiological Waste Handling System, and with other MGR systems that support the waste processing operations. The Waste Treatment Building System interfaces with the General Site Transportation System, Site Communications System, Site Water System, MGR Site Layout, Safeguards and Security System, Site Radiological Monitoring System, Site Electrical Power System, Site Compressed Air System, and Waste Treatment Building Ventilation System.
F. Habashi
Space Radiation Superconducting Shields
NASA Astrophysics Data System (ADS)
The interest on shields to protect astronauts I long term missions against GCR has recently grown and several projects have been funded. Due to their large mass, passive shields for large volume habitable modules are no longer an option and the attention is focused on the more complex, technologically challenging active systems. Among the possible solutions, the most promising is based on huge superconducting coils having a bending power sufficient to deflect out of the habitat charged particles with kinetic energy in the order of 1 GeV. Toroidal magnet systems based wound with Ti clad MgB2 conductor is proposed and described.
R-Musenich; Calvelli, V.; Farinon, S.; Burger, W. J.; Battiston, R.
According to the present invention, a shield for a glove box housing radioactive material is comprised of spaced apart clamping members which maintain three overlapping flaps in place therebetween. There is a central flap and two side flaps, the side flaps overlapping at the interior edges thereof and the central flap extending past the intersection of the side flaps in order to insure that the shield is always closed when the user withdraws his hand from the glove box. Lead loaded neoprene rubber is the preferred material for the three flaps, the extent of lead loading depending upon the radiation levels within the glove box.
Brackenbush, Larry W. (Richland, WA); Hoenes, Glenn R. (Richland, WA)
According to the present invention, a shield for a glove box housing radioactive material is comprised of spaced apart clamping members which maintain three overlapping flaps in place therebetween. There is a central flap and two side flaps, the side flaps overlapping at the interior edges thereof and the central flap extending past the intersection of the side flaps in order to insure that the shield is always closed when the user withdraws his hand from the glove box. Lead loaded neoprene rubber is the preferred material for the three flaps, the extent of lead loading depending upon the radiation levels within the glove box. 2 figs.
Brackenbush, L.W.; Hoenes, G.R.
Composition for radiation shielding
A composition for use as a radiation shield. The shield has a depleted urum core for absorbing gamma rays and a bismuth coating for preventing chemical corrosion and absorbing gamma rays. Alternatively, a sheet of gadolinium may be positioned between the uranium core and the bismuth coating for absorbing neutrons. The composition is preferably in the form of a container for storing materials that emit radiation such as gamma rays and neutrons. The container is preferably formed by casting bismuth around a pre-formed uranium container having a gadolinium sheeting, and allowing the bismuth to cool. The resulting container is a structurally sound, corrosion-resistant, radiation-absorbing container.
Kronberg, James W. (Aiken, SC)
Fermilab Booster beam collimation and shielding
The beam power in the upgraded Booster at 8 GeV and 10 Hz will be 64 kW. Beam loss can result in high radiation loads in the ring. The purpose of a new beam halo cleaning system is to localize proton losses in specially shielded regions. Calculations show that this 2-stage collimation system will localize about 99% of beam loss
N. V. Mokhovy; A. I. Drozhdin; P. H. Kasper; J. R. Lackey; E. J. Prebys; R. C. Webber
[Shielding of the geomagnetic field in apartment houses].
The present investigation has studied the specific features of shielding of the natural geomagnetic field (GMF) in the multistorey apartment houses. The results of the experimental study of the shielding properties of some building materials are presented. It is shown that there are 1.2 to 2.0-fold reductions in GMF induction within the houses depending on the number of storeys and the properties of building materials. The level of GMF within the multistorey apartment house decreases by an average of 27.2+/-0.5 microTl from the 1st to the 9th floor and the GMF attenuation factor in many apartment houses exceeds the permissible limit for working places, especially on the top floors. On designing new building materials and constructions and on architectural design, one should keep in mind their shielding properties. PMID:20000094
Chernykh, A M; Borise?ko, A N; Koval'chuk, M L
NASA Technical Reports Server (NTRS)
Simple repair technique retains cable characteristic impedance. Shielded-Cable Splicing Technique retains cable characteristic impedance. Procedure involves splicing inner conductors in staggered pattern, installing jumper braid by heat-shrinking two solder sleeves, and placing insulation sleeve over repaired section and heat-shrinking it. Two possible insulation materials are modified polyvinylidene fluoride and polytetrafluoroethylene.
Lind, W. P.; Mcgougan, W. R.
NASA Technical Reports Server (NTRS)
Cylindrical shield designed to fit around flexible pipe to protect nearby workers from injury and equipment from damage if pipe ruptures. Designed as pressure-relief device. Absorbs impact of debris ejected radially from broken flexible pipe. Also redirects flow of pressurized fluid escaping from broken pipe onto flow path allowing for relief of pressure while minimizing potential for harm.
Ponton, Michael K.; Williford, Clifford B.; Lagen, Nicholas T.
Microwave shielding measurement method
A simple system for measuring the attenuation of microwaves in the frequency range of 700 MHz to 13 GHz is described. It has been used to test a large number of commercially available microwave shielding materials. The standard system for such measurements would require IEEE STD 299 2006. This standard requires a number of different sources and receivers depending on
L. L. Hatfield; B. Schilder
A tandem warhead missile arrangement that has a composite material housing structure with a first warhead mounted at one end and a second warhead mounted near another end of the composite structure with a dome shaped composite material blast shield mounted between the warheads to protect the second warhead from the blast of the first warhead.
Mixon, Larry C. (Madison, AL); Snyder, George W. (Huntsville, AL); Hill, Scott D. (Toney, AL); Johnson, Gregory L. (Decatur, AL); Wlodarski, J. Frank (Huntsville, AL); von Spakovsky, Alexis P. (Huntsville, AL); Emerson, John D. (Arab, AL); Cole, James M. (Huntsville, AL); Tipton, John P. (Huntsville, AL)
President Clinton Defers Missile Shield Decision
NSDL National Science Digital Library
President Clinton will announce in a speech at Georgetown University today that he will not begin the initial steps to deploy a national missile defense shield, leaving the final decision to his successor. The decision to not begin construction of a radar site in Alaska, designed to track incoming missiles, was apparently the product of several factors. These include the failure of recent tests, strong opposition from Russia and some US allies, and fears that any decision would inevitably become politicized with the election nearing. Vice-President Al Gore has expressed conditional support for a missile shield, while George W. Bush has called for an even more extensive system. The President made his decision after receiving competing advice on the missile shield. William S. Cohen, the defense secretary, had recommended Mr. Clinton begin, while Samuel R. Berger, the President's national security advisor, and others recommended against construction at this point. Work on the project will continue nonetheless, including additional tests of the "kill vehicle" and a new booster rocket. The next President will decide not only whether to build the radar station and other elements of a missile shield infrastructure, but also whether to field the system and break the 1972 Antiballistic Missile Treaty.
De Nie, Michael W.
Aladdin Upgrade Design Study: Shielding.
National Technical Information Service (NTIS)
The object of this shielding is to examine all aspects of Aladdin operation to ensure that adequate shielding is provided to meet the design objectives. To do this, we will look at shielding necessary for radiation produced during the injection process, d...
P. M. DeLuca R. A. Otte S. W. Schilthelm W. P. Swanson
Solar probe shield developmental testing
NASA Technical Reports Server (NTRS)
The objectives of the Solar Probe mission and the current status of the Solar Probe thermal shield subsystem development are described. In particular, the discussion includes a brief description of the mission concepts, spacecraft configuration and shield concept, material selection criteria, and the required material testing to provide a database to support the development of the shield system.
Miyake, Robert N.
Primary shield displacement and bowing
The reactor primary shield is constructed of high density concrete and surrounds the reactor core. The inlet, outlet and side primary shields were constructed in-place using 2.54 cm (1 in) thick steel plates as the forms. The plates remained as an integral part of the shields. The elongation of the pressure tubes due to thermal expansion and pressurization is not
Capacitive Proximity Sensors With Additional Driven Shields
NASA Technical Reports Server (NTRS)
Improved capacitive proximity sensors constructed by incorporating one or more additional driven shield(s). Sensitivity and range of sensor altered by adjusting driving signal(s) applied to shield(s). Includes sensing electrode and driven isolating shield that correspond to sensing electrode and driven shield.
Mcconnell, Robert L.
Roof Shield for Advance and Retreat Mining
NASA Technical Reports Server (NTRS)
Shield sections change their configuration to suit mining mode. Articulation cylinders raise rear shield to advance position, and locking cylinders hold it there. To change to retreat position articulation cylinders lower shield. Locking pins at edge of outermost shield plate latch shield to chock base. Shield accommodates roof heights ranging from 36 to 60 inches (0.9 to 1.52 meters).
Lewis, E. V.
Comparison of deterministic and Monte Carlo methods in shielding design.
In shielding calculation, deterministic methods have some advantages and also some disadvantages relative to other kind of codes, such as Monte Carlo. The main advantage is the short computer time needed to find solutions while the disadvantages are related to the often-used build-up factor that is extrapolated from high to low energies or with unknown geometrical conditions, which can lead to significant errors in shielding results. The aim of this work is to investigate how good are some deterministic methods to calculating low-energy shielding, using attenuation coefficients and build-up factor corrections. Commercial software MicroShield 5.05 has been used as the deterministic code while MCNP has been used as the Monte Carlo code. Point and cylindrical sources with slab shield have been defined allowing comparison between the capability of both Monte Carlo and deterministic methods in a day-by-day shielding calculation using sensitivity analysis of significant parameters, such as energy and geometrical conditions. PMID:16381723
Oliveira, A D; Oliveira, C
Whipple bumper shield simulations
The Whipple bumper is a space shield designed to protect a space station from the most hazardous orbital space debris environment. A series of numerical simulations has been performed using the multi-dimensional hydrodynamics code CTH to estimate the effectiveness of the thin Whipple bumper design. These simulations are performed for impact velocities of {approximately}10 km/s which are now accessible by experiments using the Sandia hypervelocity launcher facility. For a {approximately}10 km/s impact by a 0.7 gm aluminum flier plate, the experimental results indicate that the debris cloud resulting upon impact of the bumper shield by the flier plate, completely penetrates the sub-structure. The CTH simulations also predict complete penetration by the subsequent debris cloud. 5 refs., 4 figs., 2 tabs.
Hertel, E.S.; Chhabildas, L.C. (Sandia National Labs., Albuquerque, NM (USA)); Hill, S.A. (National Aeronautics and Space Administration, Huntsville, AL (USA). George C. Marshall Space Flight Center)
An apparatus for preventing oxidation by uniformly distributing inert shielding gas over the weld area of workpieces such as pipes being welded together. The apparatus comprises a chamber and a gas introduction element. The chamber has an annular top wall, an annular bottom wall, an inner side wall and an outer side wall connecting the top and bottom walls. One side wall is a screen and the other has a portion defining an orifice. The gas introduction element has a portion which encloses the orifice and can be one or more pipes. The gas introduction element is in fluid communication with the chamber and introduces inert shielding gas into the chamber. The inert gas leaves the chamber through the screen side wall and is dispersed evenly over the weld area.
Brandt, Daniel (Los Alamos, NM)
Composition for radiation shielding
A composition for use as a radiation shield is disclosed. The shield has a depleted uranium core for absorbing gamma rays and a bismuth coating for preventing chemical corrosion and absorbing gamma rays. Alternatively, a sheet of gadolinium may be positioned between the uranium core and the bismuth coating for absorbing neutrons. The composition is preferably in the form of a container for storing materials that emit radiation such as gamma rays and neutrons. The container is preferably formed by casting bismuth around a pre-formed uranium container having a gadolinium sheeting, and allowing the bismuth to cool. The resulting container is a structurally sound, corrosion-resistant, radiation-absorbing container. 2 figs.
Kronberg, J.W.
A novel shielding material prepared from solid waste containing lead for gamma ray
NASA Astrophysics Data System (ADS)
Human beings are continuously exposed to cosmogenic radiation and its products in the atmosphere from naturally occurring radioactive materials (NORM) within Earth, their bodies, houses and foods. Especially, for the radiation protection environments where high ionizing radiation levels appear should be shielded. Generally, different materials are used for the radiation shielding in different areas and for different situations. In this study, a novel shielding material produced by a metallurgical solid waste containing lead was analyzed as shielding material for gamma radiation. The photon total mass attenuation coefficients ( ?/ ?) were measured and calculated using WinXCom computer code for the novel shielding material, concrete and lead. Theoretical and experimental values of total mass attenuation coefficient of the each studied sample were compared. Consequently, a new shielding material prepared from the solid waste containing lead could be preferred for buildings as shielding materials against gamma radiation.
Erdem, Mehmet; Baykara, Oktay; Do?ru, Mahmut; Kulu�zt�rk, Fatih
Effects of various radiation source characteristics on shielding requirements at the potential Yucca Mountain repository
This radiation shielding study provides dose rate information that can be used to estimate required shielding thicknesses for different repository configurations, including various hot cells and vaults in the waste-handling building, the boreholes in the underground emplacement area, and the transfer casks. The study determines gamma and neutron source strengths for various waste types and source geometries representative of conditions at the repository and determines dose rates as a function of shielding thickness for selected materials.
Smith, D.W.; Miller, D.D. [Bechtel National, Inc., San Francisco, CA (United States); Hill, R.R. [Sandia National Labs., Albuquerque, NM (United States)
Eruption history of the Tharsis shield volcanoes, Mars
NASA Technical Reports Server (NTRS)
The Tharsis Montes volcanoes and Olympus Mons are giant shield volcanoes. Although estimates of their average surface age have been made using crater counts, the length of time required to build the shields has not been considered. Crater counts for the volcanoes indicate the constructs are young; average ages are Amazonian to Hesperian. In relative terms; Arsia Mons is the oldest, Pavonis Mons intermediate, and Ascreaus Mons the youngest of the Tharsis Montes shield; Olympus Mons is the youngest of the group. Depending upon the calibration, absolute ages range from 730 Ma to 3100 Ma for Arsia Mons and 25 Ma to 100 Ma for Olympus Mons. These absolute chronologies are highly model dependent, and indicate only the time surficial volcanism ceased, not the time over which the volcano was built. The problem of estimating the time necessary to build the volcanoes can be attacked in two ways. First, eruption rates from terrestrial and extraterrestrial examples can be used to calculate the required period of time to build the shields. Second, some relation of eruptive activity between the volcanoes can be assumed, such as they all began at a speficic time or they were active sequentially, and calculate the eruptive rate. Volumes of the shield volcanoes were derived from topographic/volume data.
Plescia, J. B.
Analysis of the Radiation Shield of HT-7U Tokamak
NASA Astrophysics Data System (ADS)
Analysis of the radiation shield of HT-7U fusion experimental device has been presented in this contribution. An inner shield and an outer shield, is used to reduce the dose rate to the device, workers and publics. Transport calculations and analyses have been done by 3D MCNP/4C models for neutron spectrum, ? spectrum, neutron and ? dose rate levels during operation and selection of detectors. Activation calculation have been done by inventory code FISPACT to estimate the decay ? dose rate level to workers after one pulse operation of the device and the permission time for workers to get into the shield building or device to make some maintenance or replace after discharge.
Huang, Qunying; Chen, Yixue
Experimental Shielding Evaluation of the Radiation Protection Provided by Residential Structures
NASA Astrophysics Data System (ADS)
The human health and environmental effects following a postulated accidental release of radioactive material to the environment has been a public and regulatory concern since the early development of nuclear technology and researched extensively to better understand the potential risks for accident mitigation and emergency planning purposes. The objective of this investigation is to research and develop the technical basis for contemporary building shielding factors for the U.S. housing stock. Building shielding factors quantify the protection a certain building-type provides from ionizing radiation. Much of the current data used to determine the quality of shielding around nuclear facilities and urban environments is based on simplistic point-kernel calculations for 1950's era suburbia and is no longer applicable to the densely populated urban environments seen today. To analyze a building's radiation shielding properties, the ideal approach would be to subject a variety of building-types to various radioactive materials and measure the radiation levels in and around the building. While this is not entirely practicable, this research uniquely analyzes the shielding effectiveness of a variety of likely U.S. residential buildings from a realistic source term in a laboratory setting. Results produced in the investigation provide a comparison between theory and experiment behind building shielding factor methodology by applying laboratory measurements to detailed computational models. These models are used to develop a series of validated building shielding factors for generic residential housing units using the computational code MCNP5. For these building shielding factors to be useful in radiologic consequence assessments and emergency response planning, two types of shielding factors have been developed for; (1) the shielding effectiveness of each structure within a semi-infinite cloud of radioactive material, and (2) the shielding effectiveness of each structure from contaminant deposition on the roof and surrounding surfaces. For example, results from this investigation estimate the building shielding factors from a semi-infinite plume between comparable two-story models with a basement constructed with either brick-and-mortar or vinyl siding composing the exterior wall weather and a typical single-wide manufactured home with vinyl siding to be 0.36, 0.65, and 0.82 respectively.
Dickson, Elijah D.
Iron shielded MRI optimization
NASA Astrophysics Data System (ADS)
The design of the main current systems of an actively shielded and of an iron shielded MRI device for nuclear resonance imaging, is considered. The model for the analysis of the magnetic induction produced by the current system, is based on the combination of a Boundary Element technique and of the integration of two Fredholm integral equations of the first and the second kind. The equivalent current magnetization model is used for the calculation of the magnetization produced by the iron shield. High field uniformity in a spherical region inside the device, and a low stray field in the neighborhood of the device are required. In order to meet the design requirements a multi-objective global minimization problem is solved. The minimization method is based on the combination of the filled function technique and the (1+1) evolution strategy algorithm. The multi-objective problem is treated by means of a penalty method. The actively shielded MRI system results to utilize larger amount of conductor and produce higher magnetic energy than the iron shield device. On veut �tudier le projet du syst�me des courants principaux d'un MRI � �cran en fer et d'un MRI � �cran actif. Le mod�le d'analyse du champ magn�tique produit par le syst�me de courants est bas� sur la combinaison d'une technique Boundary Element et de l'int�gration de deux �quations int�grales de Fredholm de premi�re et de seconde sorte. On utilise pour calculer la magn�tisation produite par l'�cran en fer le mod�le � cou rants de magn� ti sa tion �quivalents. On exige une �l�vation uniforme du champ dans une r�gion sph�rique au c�ur de l'appareil et un bas champ magn�tique dispers� � proximit� de l'appareil. Dans le but de r�pondre aux imp�ratifs du projet, on va r�soudre un probl�me multiobjectif de minimisation globale. On utilise une technique de minimisation obtenue par la combinaison des m�thodes �Filled Function� et �(1+1) Evolution Strategy�. Le probl�me multiobjectif est trait� avec la m�thode des p�nalit�s. Il s'ensuit que le MRI � �cran actif utilise une plus grande quantit� de conducteur et produit une �nergie magn�tique plus �lev�e que le MRI � �cran en fer.
Borghi, C. A.; Fabbri, M.
Experimental performance investigation of double-layer shields at power frequency magnetic shielding
Double-layer shields have received attention in magnetic shielding at extremely low frequency. Also, cylindrical shape is one of shielding structures widely used in industry. In this study, cylindrical shaped shields with commonly available and inexpensive materials used for power frequency magnetic field shielding. The magnetic shielding performances are investigated experimentally for single and double-layer shields at power frequencies. The aim
Selim Koroglu; Nurettin Umurkan; Osman Kilic
Measurement of the transient shielding effectiveness of shielding cabinets
NASA Astrophysics Data System (ADS)
Recently, new definitions of shielding effectiveness (SE) for high-frequency and transient electromagnetic fields were introduced by Klinkenbusch (2005). Analytical results were shown for closed as well as for non closed cylindrical shields. In the present work, the shielding performance of different shielding cabinets is investigated by means of numerical simulations and measurements inside a fully anechoic chamber and a GTEM-cell. For the GTEM-cell-measurements, a downscaled model of the shielding cabinet is used. For the simulations, the numerical tools CONCEPT II and COMSOL MULTIPHYSICS were available. The numerical results agree well with the measurements. They can be used to interpret the behaviour of the shielding effectiveness of enclosures as function of frequency. From the measurement of the electric and magnetic fields with and without the enclosure in place, the electric and magnetic shielding effectiveness as well as the transient shielding effectiveness of the enclosure are calculated. The transient SE of four different shielding cabinets is determined and discussed.
Herlemann, H.; Koch, M.
Soil-structure interaction in shield tunnelling in soft soil
The development and extension of large cities creates a need for multiple shallow tunnels in the soft ground of building areas. Prediction of the ground settlement caused by the tunnel excavation is a major engineering challenge. A numerical simulation using a finite element method was implemented in the aim of developing a procedure to predict the movement induced by shield
S. Bernat; B. Cambou
11. Photocopy of drawing, February 1958. WATERTOWN ARSENAL REACTOR, SHIELD ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
11. Photocopy of drawing, February 1958. WATERTOWN ARSENAL REACTOR, SHIELD STRUCTURE, SECTIONS, AND PLANS. Bendix Aviation Corporation; and Giffels & Vallet, Inc., L. Rosetti, Associated Architects and Engineers, Detroit, Michigan. Drawing Number 53-198. (Original: AMTL Engineering Division, Watertown). - Watertown Arsenal, Building No. 100, Wooley Avenue, Watertown, Middlesex County, MA
Underground barrier construction apparatus with soil-retaining shield
An apparatus for building a horizontal underground barrier by cutting through soil and depositing a slurry, preferably one which cures into a hardened material. The apparatus includes a digging means for cutting and removing soil to create a void under the surface of the ground, a shield means for maintaining the void, and injection means for inserting barrier-forming material into
Bradley M. Gardner; Ann Marie Smith; Richard W. Hanson; Richard T. Hodges
Radiation shielding study for superconducting RF cavity test facility at Fermilab
The results of Monte Carlo radiation shielding study performed with the MARS15 code for the vertical test cryostat facility to be installed in the Industrial Building 1 at Fermilab are presented and discussed.
Rakhno, I.; /Fermilab
Radiation shielding quality assurance
NASA Astrophysics Data System (ADS)
For the radiation shielding quality assurance, the validity and reliability of the neutron transport code MCNP, which is now one of the most widely used radiation shielding analysis codes, were checked with lot of benchmark experiments. And also as a practical example, follows were performed in this thesis. One integral neutron transport experiment to measure the effect of neutron streaming in iron and void was performed with Dog-Legged Void Assembly in Knolls Atomic Power Laboratory in 1991. Neutron flux was measured six different places with the methane detectors and a BF-3 detector. The main purpose of the measurements was to provide benchmark against which various neutron transport calculation tools could be compared. Those data were used in verification of Monte Carlo Neutron & Photon Transport Code, MCNP, with the modeling for that. Experimental results and calculation results were compared in both ways, as the total integrated value of neutron fluxes along neutron energy range from 10 KeV to 2 MeV and as the neutron spectrum along with neutron energy range. Both results are well matched with the statistical error +/-20%. MCNP results were also compared with those of TORT, a three dimensional discrete ordinates code which was developed by Oak Ridge National Laboratory. MCNP results are superior to the TORT results at all detector places except one. This means that MCNP is proved as a very powerful tool for the analysis of neutron transport through iron & air and further it could be used as a powerful tool for the radiation shielding analysis. For one application of the analysis of variance (ANOVA) to neutron and gamma transport problems, uncertainties for the calculated values of critical K were evaluated as in the ANOVA on statistical data.
Um, Dallsun
Removable cleanable antireflection shield
NASA Astrophysics Data System (ADS)
A replaceable anti-reflection shield for the glare surface beneath the windscreen an aircraft is described which comprises a flexible panel of light absorbing material, such as black cloth, velvet, canvas or plastic, of size and configuration corresponding to that of the glare surface for placement on and conformance to the contour of the glare surface beneath the windscreen, and peripheral attaching means such as adhesive strips, snaps. Velcro strips, suction cups, or similar devices, on the flexible panel for detachably securing the peripheral edges of the panel to the glare surface. Whereby the panel is easily removed for cleaning or replacement.
Task, H. L.
Spacecraft ceramic protective shield
NASA Technical Reports Server (NTRS)
A low areal density protective shield apparatus, and method for making same, for protecting spacecraft structures from impact with hypervelocity objects, including a bumper member comprising a bumper ceramic layer, a bumper shock attenuator layer, and a bumper confining layer. The bumper ceramic layer can be SiC or B.sub.4 C; the bumper shock attenuator layer can be zirconia felt; and the bumper confining layer can be aluminum. A base armor member can be spaced from the bumper member and a ceramic fiber-based curtain can be positioned between the bumper and base armor members.
Larriva, Rene F. (Inventor); Nelson, Anne (M.); Czechanski, James G. (Inventor); Poff, Ray E. (Inventor)
NASA Technical Reports Server (NTRS)
Performances of three types of heat protectors predicted. Estimates of expected performances of heat shields for conical drag brake presented in paper. Drag brakes, or aerobrakes, being considered as devices for slowing space vehicles when they return to Space Shuttle altitudes from higher satellite altitudes after supply missions. Aerobrakes add less weight than do retro-rockets for same purpose and consume no fuel. Paper provides general information on sensitivity of performance to thermal and physical properties of materials used in aerobrakes. Information useful to both designers of brakes and developers of materials for brake fabrication on aerospace structures.
Pitts, W. C.; Murbach, M. S.
Shielding effects in ceramic superconductors
The shielding properties of high-temperature superconductors in DC and AC magnetic fields are discussed using Bean's critical-state model and models, which account for the field dependence of the critical current density. Experimental work on the shielding properties of superconducting YBa2Cu3O7-delta and conductive (aluminum and cooper) screens is presented. The maximum value of the shielded field for YBa2Cu3O7-delta\\/Ag screens was measured
Halina Niculescu; Rainer Schmidmeier; Betina Topolski; Peter J. Gielisse
NASA Technical Reports Server (NTRS)
Aircraft wiring subjected to rapidly changing electromagnetic fields was considered. The ways in which shielded cables reduce surge voltages were studied along with the ways in which common practice regarding the use of shields may be at variance with the use required for the control of lightning effects. Courses in which this apparent conflict of use may be resolved were suggested. Noise currents flowing on shields of cables related to the noise signals coupled onto signal conductors were also investigated.
NASA Technical Reports Server (NTRS)
A hypervelocity impact shield and method for protecting a wall structure, such as a spacecraft wall, from impact with particles of debris having densities of about 2.7 g/cu cm and impact velocities up to 16 km/s are disclosed. The shield comprises a stack of ultra thin sheets of impactor disrupting material supported and arranged by support means in spaced relationship to one another and mounted to cover the wall in a position for intercepting the particles. The sheets are of a number and spacing such that the impacting particle and the resulting particulates of the impacting particle and sheet material are successively impact-shocked to a thermal state of total melt and/or vaporization to a degree as precludes perforation of the wall. The ratio of individual sheet thickness to the theoretical diameter of particles of debris which may be of spherical form is in the range of 0.03 to 0.05. The spacing between adjacent sheets is such that the debris cloud plume of liquid and vapor resulting from an impacting particle penetrating a sheet does not puncture the next adjacent sheet prior to the arrival thereat of fragment particulates of sheet material and the debris particle produced by a previous impact.
Cour-Palais, Burton G. (inventor); Crews, Jeanne Lee (inventor)
Shielded enclosures for experimental studies of shielding topology
The report discusses the effort to provide shielded enclosures for EMP experimental studies of shielding topology. Section 1 discusses the theoretical modeling for which scattering matrices of subshields and their norms are used to relate the internal signals to the electromagnetic source environment. Both the line and aperture penetrations are included in the scattering matrix formulation. Experimental and analytical methods
F. C. Yang; K. S. H. Lee; S. A. Kokorowski; C. E. Baum; J. Hamm; W. Graf; E. F. Vance
PBF Cubicle 13. Shield wall details illustrate shielding technique of ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
PBF Cubicle 13. Shield wall details illustrate shielding technique of stepped penetrations and brick layout scheme for valve stem extension sleeve. Aerojet Nuclear Company. Date: May 1976. INEEL index no. 761-0620-00-400-195280 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID
Shield Defense of a Larval Tortoise Beetle
Larvae of the folivorous tortoise beetle, Plagiometriona clavata, carry shields formed from feces and exuviae above their bodies. We used an ecologically relevant predatory ant, Formica subsericea, in a bioassay to determine if shields functioned as simple barriers, as previous studies indicated, or whether they were chemical defenses. Shields were necessary for larval survival; shield removal rendered larvae vulnerable. Shields
Fredric V. Vencl; Timothy C. Morton; Ralph O. Mumma; Jack C. Schultz
Enhanced meteoroid and orbital debris shielding
An innovative, low-weight shield system has been developed by NASA Johnson Space Center (JSC) and Marshall Space Flight Center (MSFC) engineers to enhance the protection of conventional Whipple shields. This shield, the �Stuffed Whipple� shield, includes a flexible blanket combining Nextel� ceramic fabric and Kevlar� fabric (or �stuffing�) between the aluminum bumper and rear wall of a Whipple shield. The
E. L. Christiansen; J. L. Crews; J. E. Williamsen; J. H. Robinson; A. M. Nolen
Topographic evidence for shield volcanism on Io
Similarities between terrestrial shield volcanoes and a volcano on Io observed in Voyager I imagery of the satellite at 30/sup 0/ S, 246/sup 0/ W are delineated. A photoclinometry model was used to numerically estimate the slope based on the Minnaert photometric function. The slope values are accurate to within 10 deg on the sun-facing slope and 1 deg on the shadow side. As found with shield volcanoes, the feature has a central edifice, 40-50 km in diameter, and a broad, elliptical base, 77 x 90 km across. The summit of the Io volcano is 2.2-2.8 km above the surrounding plane and contains a caldera about 5 km in diameter. The similarity in shape between basaltic terrestrial shield volcanoes and the Io volcano indicates that the Io feature may also be composed of basalt. The composition could be sulfur if the heat flow was under 0.05 W/sq m, as it might have been in later stages of formation. 9 references.
Moore, J.M.; Mcewen, A.S.; Albin, E.F.; Greeley, R.
Electroless techniques for EMI shieldings
This paper discusses the progress made in electroless plating techniques for fabrication of EMI shieldings. Although, there are alternative techniques such as zinc arc spray, Cu or Ni conductive paints and RF\\/magnetron sputtering for deposition of conductive coatings on plastics, electroless techniques have advantage of better uniformity and adhesivity of coatings as well as higher shielding effectiveness. However, these techniques
L. G. Bhatgadde; S. Joseph
Reflective Shields for Artificial Satellites
NASA Technical Reports Server (NTRS)
Report proposes reflective shield that protects spacecraft from radiant energy. Also gives some protection against particle beams and cosmic rays. Conceptual shield essentially advanced version of decorative multifaceted mirror balls often hung over dance floors. Mirror facets disperse radiant energy in many directions.
Bouquet, F. L.
Radiation Shielding Optimization on Mars
NASA Technical Reports Server (NTRS)
Future space missions to Mars will require radiation shielding to be optimized for deep space transit and an extended stay on the surface. In deep space, increased shielding levels and material optimization will reduce the exposure from most solar particle events (SPE) but are less effective at shielding against galactic cosmic rays (GCR). On the surface, the shielding provided by the Martian atmosphere greatly reduces the exposure from most SPE, and long-term GCR exposure is a primary concern. Previous work has shown that in deep space, additional shielding of common materials such as aluminum or polyethylene does not significantly reduce the GCR exposure. In this work, it is shown that on the Martian surface, almost any amount of aluminum shielding increases exposure levels for humans. The increased exposure levels are attributed to neutron production in the shield and Martian regolith as well as the electromagnetic cascade induced in the Martian atmosphere. This result is significant for optimization of vehicle and shield designs intended for the surface of Mars.
Slaba, Tony C.; Mertens, Chris J.; Blattnig, Steve R.
Lunar Surface Reactor Shielding Study
A nuclear reactor system could provide power to support long term human exploration of the moon. Such a system would require shielding to protect astronauts from its emitted radiations. Shielding studies have been performed for a Gas Cooled Reactor system because it is considered to be the most suitable nuclear reactor system available for lunar exploration, based on its tolerance
Shawn Kang; Ronald Lipinski; William McAlpine
NASA Technical Reports Server (NTRS)
The sensitivity of silica heat shield requirements to gap width, tile edge radius, and heat transfer distribution within tile gaps was investigated. A two-dimensional thermal model was modified and used to determine the effect of two dimensional heat transfer distributions at high temperature reusable surface insulation edges on shuttle thermal protection system (TPS) requirements. The sensitivity of TPS requirements to coating thickness, emissivity, substructure thickness, and changes in gap heating for several locations on shuttle was also studied. An inverse solution technique was applied to temperature data obtained in the Ames 20 MW turbulent duct in order to examine the effect of tile edge radius on TPS requirements. The derived heating values were then used to predict TPS requirements. Results show that increasing tile radius reduces TPS requirements.
Ebbesmeyer, L. H.; Christensen, H. E.
Portable convertible blast effects shield
A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.
Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler,; Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A (Livermore, CA)
Portable convertible blast effects shield
A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.
Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler, Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A (Livermore, CA)
Portable convertible blast effects shield
A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more frusto-conically-tapered telescoping rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration by the friction fit of adjacent pairs of frusto-conically-tapered rings to each other.
Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler, Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A. (Livermore, CA)
Aladdin upgrade design study: shielding
The object of this shielding is to examine all aspects of Aladdin operation to ensure that adequate shielding is provided to meet the design objectives. To do this, we will look at shielding necessary for radiation produced during the injection process, during normal loss of the stored beam and during accidental loss of the stored beam. It will therefore be necessary to specify shielding not only at the ring, but also along the injection line and the optical beam lines. We will also give special attention to the occupation of the accelerator Vault during injection as this may be a desirable design option. In effect, two shielding plans will be presented, permitting estimates of cost and space requirements for both.
Swanson, W.P.; DeLuca, P.M. Jr.; Otte, R.A.; Schilthelm, S.W.
Welding shield for coupling heaters
Systems for coupling end portions of two elongated heater portions and methods of using such systems to treat a subsurface formation are described herein. A system may include a holding system configured to hold end portions of the two elongated heater portions so that the end portions are abutted together or located near each other; a shield for enclosing the end portions, and one or more inert gas inlets configured to provide at least one inert gas to flush the system with inert gas during welding of the end portions. The shield may be configured to inhibit oxidation during welding that joins the end portions together. The shield may include a hinged door that, when closed, is configured to at least partially isolate the interior of the shield from the atmosphere. The hinged door, when open, is configured to allow access to the interior of the shield.
Menotti, James Louis (Dickinson, TX)
The effect of breast shielding during lumbar spine radiography
Background The aim of the study was to determine the influence of lead shielding on the dose to female breasts in conventional x-ray lumbar spine imaging. The correlation between the body mass index and the dose received by the breast was also investigated. Materials and methods Breast surface dose was measured by thermoluminescent dosimeters (TLD). In the first phase measurements of breast dose with and without shielding from lumbar spine imaging in two projections were conducted on an anthropomorphic phantom. In the second stage measurements were performed on 100 female patients, randomly divided into two groups of 50, with breast shielding only used in one group. Results On average, breast exposure dose in lumbar spine imaging in both projections (anteroposterior (AP) and lateral) was found reduced by approximately 80% (p < 0,001) when shielding with 0.5 mm lead equivalent was used (from 0.45�0.25 mGy to 0.09�0.07 mGy on the right and from 0.26�0.14 mGy to 0.06�0.04 mGy on the left breast). No correlation between the body mass index (BMI) and the breast surface radiation dose was observed. Conclusions Although during the lumbar spine imaging breasts receive low-dose exposure even when shielding is not used, the dose can be reduced up to 80% by breast shielding with no influence on the image quality.
Mekis, Nejc; Zontar, Dejan; Skrk, Damijan
Preliminary design of magnetic shielding by FEM
In this paper, the authors propose an optimization method for magnetic shielding. The main purpose is the weight reduction of shield material. Assuming that the permeability of shield material is infinite, they simplify the magnetic shielding problem. Under this assumption, they design optimal passage for magnetic flux through the shield. They apply this method to designing the magnetic shielding for Maglev and show the effectiveness of this method by experimental and numerical data.
Sasakawa, Takashi; Tagawa, Naoto; Herai, Toshiki; Tomita, Masaru [Railway Technical Research Inst., Kokubunji, Tokyo (Japan)] [Railway Technical Research Inst., Kokubunji, Tokyo (Japan)
Lunar Surface Reactor Shielding Study
NASA Astrophysics Data System (ADS)
A nuclear reactor system could provide power to support long term human exploration of the moon. Such a system would require shielding to protect astronauts from its emitted radiations. Shielding studies have been performed for a Gas Cooled Reactor system because it is considered to be the most suitable nuclear reactor system available for lunar exploration, based on its tolerance of oxidizing lunar regolith and its good conversion efficiency. The goals of the shielding studies were to determine a material shielding configuration that reduces the dose (rem) to the required level in order to protect astronauts, and to estimate the mass of regolith that would provide an equivalent protective effect if it were used as the shielding material. All calculations were performed using MCNPX, a Monte Carlo transport code. Lithium hydride must be kept between 600 K and 700 K to prevent excessive swelling from large amounts of gamma or neutron irradiation. The issue is that radiation damage causes separation of the lithium and the hydrogen, resulting in lithium metal and hydrogen gas. The proposed design uses a layer of B4C to reduce the combined neutron and gamma dose to below 0.5Grads before the LiH is introduced. Below 0.5Grads the swelling in LiH is small (less than about 1%) for all temperatures. This approach causes the shield to be heavier than if the B4C were replaced by LiH, but it makes the shield much more robust and reliable.
Kang, Shawn; Lipinski, Ronald; McAlpine, William
Investigating Radiation Shielding Properties of Different Mineral Origin Heavyweight Concretes
NASA Astrophysics Data System (ADS)
The radiation although has hazardous effects for human health, developing technologies bring lots of usage fields to radiation like in medicine and nuclear power station buildings. In this case protecting from undesirable radiation is a necessity for human health. Heavyweight concrete is one of the most important materials used in where radiation should be shielded, like those areas. In this study, used heavyweight aggregates of different mineral origin (Limonite, Siderite), in order to prepare different series in concrete mixtures and investigated radiation shielding properties. The experimental results on measuring the radiation shielding, the heavyweight concrete prepared with heavyweight aggregates of different mineral origin show that, are useful radiation absorbents when they used in concrete mixtures.
Basyigit, Celalettin; Uysal, Volkan; Kilin�arslan, ?emsettin; Mavi, Bet�l; G�no?lu, Kadir; Akkurt, Iskender; Akka?, Ay?e
Radiation Shielding Properties of Some Marbles in Turkey
NASA Astrophysics Data System (ADS)
Especially after development of technology, radiation started to be used in a large fields such as medicine, industry and energy. Using radiation in those fields bring hazordous effect of radition into humancell. Thus radiation protection becomes important in physics. Although there are three ways for radiation protection, shielding of the radiation is the most commonly used method. Natural Stones such as marble is used as construction material especially in critical building and thus its radiation shielding capability should be determined. In this study, gamma ray shielding properties of some different types of marble mined in Turkey, have been measured using a NaI(Tl) scintillator detector. The measured results were also compared with the theoretical calculations XCOM.
G�no?lu, K.; Akkurt, I.
Radiation Shielding Properties of Some Marbles in Turkey
Especially after development of technology, radiation started to be used in a large fields such as medicine, industry and energy. Using radiation in those fields bring hazardous effect of radiation into humancell. Thus radiation protection becomes important in physics. Although there are three ways for radiation protection, shielding of the radiation is the most commonly used method. Natural Stones such as marble is used as construction material especially in critical building and thus its radiation shielding capability should be determined.In this study, gamma ray shielding properties of some different types of marble mined in Turkey, have been measured using a NaI(Tl) scintillator detector. The measured results were also compared with the theoretical calculations XCOM.
Guenoglu, K.; Akkurt, I. [Sueleyman Demirel University, Faculty of Arts and Sciences, Dept. of Physics, Isparta (Turkey)
Static Aerodynamic Performance Investigation of a Fluid Shield Nozzle
NASA Technical Reports Server (NTRS)
In pursuit of an acoustically acceptable, high performance exhaust system capable of meeting Federal Aviation Regulation 36 Stage 3 noise goals for the High Speed Civil Transport application, General Electric Aircraft Engines conducted a design study to incorporate a fluid shield into a 36-chute suppressor exhaust-nozzle system. After a full scale preliminary mechanical design of the resulting fluid shield exhaust system, scale model aerodynamic performance tests and acoustic tests were conducted to establish both aerodynamic performance and acoustic characteristics. Data are presented as thrust coefficients, discharge coefficients, chute-base pressure drags, and plug static pressure distributions.
Balan, C.; Askew, J. W.
NASA Technical Reports Server (NTRS)
The Wake Shield Facility is a free-flying research and development facility that is designed to use the pure vacuum of space to conduct scientific research in the development of new materials. The thin film materials technology developed by the WSF could some day lead to applications such as faster electronics components for computers. The WSF Free-Flyer is a 12-foot-diameter stainless steel disk that, while traveling in orbit at approximately 18,000 mph, leaves in its wake a vacuum 1,000 to 10,000 times better than the best vacuums currently achieved on Earth. While it is carried into orbit by the Space Shuttle, the WSF is a fully equipped spacecraft in its own right, with cold gas propulsion for separation from the orbiter and a momentum bias attitude control system. All WSF functions are undertaken by a spacecraft computer with the WSF remotely controlled from the ground. The ultra vacuum, nearly empty of all molecules, is then used to conduct a series of thin film growths by a process called epitaxy which produces exceptionally pure and atomically ordered thin films of semiconductor compounds such as gallium arsenide. Using this process, the WSF offers the potential of producing thin film materials, and the devices they will make possible.
Radiation shielding for neutron guides
NASA Astrophysics Data System (ADS)
Models of the neutron guide shielding for the out of bunker guides on the thermal and cold neutron beam lines of the OPAL Reactor (ANSTO) were constructed using the Monte Carlo code MCNP 4B. The neutrons that were not reflected inside the guides but were absorbed by the supermirror (SM) layers were noted to be a significant source of gammas. Gammas also arise from neutrons absorbed by the B, Si, Na and K contained in the glass. The proposed shielding design has produced compact shielding assemblies. These arrangements are consistent with safety requirements, floor load limits, and cost constraints. To verify the design a prototype was assembled consisting of 120 mm thick Pb(96%)Sb(4%) walls resting on a concrete block. There was good agreement between experimental measurements and calculated dose rates for bulk shield regions.
Ersez, T.; Braoudakis, G.; Osborn, J. C.
Radiation Distributions for Shielding Calculations.
National Technical Information Service (NTIS)
Sensitivity studies have indicated that representative neutron and secondary gamma-ray energy and angle distributions can be used for structure shielding analysis thereby eliminating the need for extensive transport calculations using many sources. A revi...
L. G. Mooney
Integral Face Shield Concept for Firefighter's Helmet
NASA Technical Reports Server (NTRS)
Stowable face shield could be made integral part of helmet worn by firefighters. Shield, made from same tough clear plastic as removable face shields presently used, would be pivoted at temples to slide up inside helmet when not needed. Stowable face shield, being stored in helmet, is always available, ready for use, and is protected when not being used.
Abeles, F.; Hansberry, E.; Himel, V.
Magnetic shielding for magnetically levitated vehicles
The magnetic shielding required for magnetically levitated vehicles is discussed. Shielding is needed to protect passengers in a vehicle from stray dc magnetic fields coming from the superconducting dipoles carried by the vehicle. In addition, the superconducting dipoles must be shielded against various ac magnetic fields. Here we consider shielding of ac magnetic fields generated by the propulsion windings for
YUKIKAZU IWASA; Francis Bitter
Magnetic Shield for Adiabatic Demagnetization Refrigerators (ADR)
NASA Technical Reports Server (NTRS)
A new method was developed for creating a less expensive shield for ADRs using 1018 carbon steel. This shield has been designed to have similar performance to the expensive vanadium permendur shields, but the cost is 30 to 50% less. Also, these shields can be stocked in a variety of sizes, eliminating the need for special forgings, which also greatly reduces cost.
Chui, Talso C.; Haddad, Nicolas E.
Gamma shielding factor for typical houses in Brazil.
The housing features in a country depend much on its climate. Dwellings in warm countries are much lighter constructions than in cold ones, which will reflect on the amount of shielding against radiation they provide. In addition to that, wealth is another factor that influences the building's finishing. Great effort has been taken to determine parameters to more accurately estimate dose to a population in case of a radioactive or nuclear accident. Nevertheless, most available data are concerned with typical housing in cold climate countries. This study aims to determine shielding factors for typical building materials used in the southeast of Brazil, a warm area, due to radioactive material deposited on the surrounding field, walls and ceiling of the external surfaces. The shielding factors determination was performed by simulation with the MCNP5 Monte Carlo computer code. The air kerma indoors for the 300, 662 and 3000 keV photon energies have been determined for three different housing patterns, ranging from the very simple to a very complex structure. The shielding factor, defined as the ratio of the air kerma indoor to the air kerma in open field, for the most simple house type and 300 keV photon energy was found to be twice of the best finished one for the same energy. PMID:16782986
Salinas, I C P; Conti, C C; Rochedo, E R R; Lopes, R T
Numerical Approach for Computation of Electromagnetic Shielding
NASA Astrophysics Data System (ADS)
Disturbing magnetic field (so-called magnetic smog) can be in certain areas suppressed by shielding jacket. Disturbing field is possible to be "lead away" from the shielded area with the use of jacket made of materials with high magnetic permeability (so-called passive shielding, or flux-entrapment shielding). If the disturbing field is time-variable, eddy currents are induced into electrically conductive jacket. Magnetic field generated by these eddy currents suppress the disturbing field (this is called active shielding, or lossy magnetic shielding). Both of these principles can be applied altogether (this is called combined shielding). Presented paper states numerical approach to shielding jacket design and is an introduction to following solution of a real problem of magnetic shielding when the disturbing magnetic field is space-time complicated. Effective design of the magnetic shielding should then be formulated as an optimization task.
Mayer, Daniel; Ulrych, Bohu�
Shielding effectiveness of copper-clad steel materials for communications shielding
The objective of this paper is to determine the shielding effectiveness of copper-clad stainless steel shields in order to compare their performance with other conventional shield materials such as pure copper, copper alloys, and copolymer coated aluminum. A short review of a number of techniques for measuring shielding effectiveness of cable shielding is given. The techniques selected for this paper
O. M. Salati; R. Raman
Magmatic Volatiles and Low Pressure Degassing at a Mafic Shield Volcano (Belknap) in the Oregon Cascades
NASA Astrophysics Data System (ADS)
Cinder cones and shield volcanoes frequently coexist in volcanic fields. Despite their proximity, cinder cones often erupt as monogenetic (single) events, whereas shield volcanoes are polygenetic (multiple eruptive events). Why some vents erupt once for a relatively short period of time (months) but others nearby remain active enough to build up as shields (over hundreds or thousands of years) remains ambiguous. To better understand the magma ascent conditions associated with these disparate eruption styles, we contrast the volatile concentrations within olivine-hosted melt inclusions of tephra deposits from the late-stage eruptions of a mafic shield volcano with those from nearby cinder cones. Belknap Crater is a shield volcano in the Central Oregon High Cascades that grew through repeated eruptions from ~2800 to 1500 years BP (Sherrod et al., 2004). Volatile contents from late-stage ash collected on the flanks of the summit cone range from 0.1 to 2.4 wt% H2O and <50 to 770 ppm CO2. The most volatile-rich inclusions record vapor saturation pressures of ~2 kbar, equivalent to ~7 km depth in the crust, whereas inclusions with the lowest volatile contents indicate very low pressures of formation. Given that the height of the volcano is roughly 540 meters above the surrounding ground level, many of the inclusions with relatively low H2O values and CO2 values, which are often below detection limits, likely reflect olivine crystallization within the volcano itself. In contrast, melt inclusions from nearby short-lived cinder cones (e.g. Collier Cone and 4-in-1 Cone) of similar age, < 2900 years BP, contain 2-4 wt% H2O and 500-1200 ppm CO2. These inclusions lack the low H2O, low CO2 values found at Belknap - even in deposits representing the final stages of explosive activity - and record crystallization at pressures between ~1-2 kbar, equivalent depth of ~4-8 km depth in the crust. H2O-CO2 patterns in inclusions from Belknap are similar to those observed in the late-stage inclusions from long-lived, 10-15 year eruptions at Volc�n Jorullo and Par�cutin in Mexico. The trend from deep to shallow crystallization pressures in these systems suggests that later magma is stored at shallow levels, where it experiences extensive degassing and crystallization prior to eruption. The differences between the degassing patterns inferred from Belknap inclusions and those from most cinder cones in the Oregon Cascades suggest that the subsurface magma plumbing systems beneath these types of volcanoes are different. Specifically, Belknap apparently developed a complex magma plumbing system capable of stalling an ascending batch of magma at shallow depths. In contrast, the plumbing systems beneath many of the Central Oregon High Cascades cinder cones appear to promote rapid migration of magma to the surface.
Mordensky, S. P.; Ruscitto, D. M.; Wallace, P. J.; Cashman, K. V.
Evaluation of solders for superconducting magnetic shield
This paper reports on magnetic shield with superconducting winding studied aiming at the practical application of the shield in a magnetic field of higher than 3T. Tubular magnetic shields have been fabricated with superconducting winding using NbTi multifilamentary composite wires. The shields were impregnated with two kinds of solders (wood's metal and indium) to make the electric joint between the wires. The characteristics of the shields are thought to be controlled predominantly by the quality of the solder.
Seo, K.; Nishijima, S.; Katagiri, K.; Okada, T. (ISIR Osaka Univ., Mihogaoka, Ibaraki, Osaka 567 (JP))
Electrodynamic Dust Shield Demonstrator
NASA Technical Reports Server (NTRS)
The objective of the project was to design and manufacture a device to demonstrate a new technology developed by NASA's Electrostatics and Surface Physics Laboratory. The technology itself is a system which uses magnetic principles to remove regolith dust from its surface. This project was to create an enclosure that will be used to demonstrate the effectiveness of the invention to The Office of the Chief Technologist. ONE of the most important challenges of space exploration is actually caused by something very small and seemingly insignificant. Dust in space, most notably on the moon and Mars, has caused many unforeseen issues. Dirt and dust on Earth, while a nuisance, can be easily cleaned and kept at bay. However, there is considerably less weathering and erosion in space. As a result, the microscopic particles are extremely rough and abrasive. They are also electrostatically charged, so they cling to everything they make contact with. This was first noted to be a major problem during the Apollo missions. Dust would stick to the spacesuits, and could not be wiped off as predicted. Dust was brought back into the spacecraft, and was even inhaled by astronauts. This is a major health hazard. Atmospheric storms and other events can also cause dust to coat surfaces of spacecraft. This can cause abrasive damage to the craft. The coating can also reduce the effectiveness of thermal insulation and solar panels.' A group of engineers at Kennedy Space Center's Electrostatics and Surface Physics Laboratory have developed a new technology, called the Electrodynamic Dust Shield, to help alleviate these problems. It is based off of the electric curtain concept developed at NASA in 1967. "The EDS is an active dust mitigation technology that uses traveling electric fields to transport electrostatically charged dust particles along surfaces. To generate the traveling electric fields, the EDS consists of a multilayer dielectric coating with an embedded thin electrode grid running a multiphase low frequency AC signal. Electrostatically charged particles, such as those encountered on the moon, Mars, or an asteroid, are carried along by the traveling field due to the action of Coulomb and dielectrophoretic forces."2 The technical details have been described in a separate article. This document details the design and construction process of a small demonstration unit. Once finished, this device will go to the Office of the ChiefTechnologist at NASA headquarters, where it will be used to familiarize the public with the technology. 1 NASA KSC FO Intern, Prototype Development Laboratory, Kennedy Space Center, University of Central Florida Kennedy Space
Stankie, Charles G.
Structural Design and Thermal Analysis for Thermal Shields of the Mice Coupling Magnets
NASA Astrophysics Data System (ADS)
A superconducting coupling magnet made from copper matrix NbTi conductors operating at 4 K will be used in the Muon Ionization Cooling Experiment (MICE) to produce up to 2.6 T on the magnet centerline to keep the muon beam within the thin RF cavity windows. The coupling magnet is to be cooled by two cryocoolers with a total cooling capacity of 3 W at 4.2 K. In order to keep a certain operating temperature margin, the most important is to reduce the heat leakage imposed on cold surfaces of coil cold mass assembly. An intermediate temperature shield system placed between the coupling coil and warm vacuum chamber is adopted. The shield system consists of upper neck shield, main shields, flexible connections and eight supports, which is to be cooled by the first stage cold heads of two cryocoolers with cooling capacity of 55 W at 60 K each. The maximum temperature difference on the shields should be less than 20 K, so the thermal analyses for the shields with different thicknesses, materials, flexible connections for shields' cooling and structure design for their supports were carried out. 1100 Al is finally adopted and the maximum temperature difference is around 15 K with 4 mm shield thickness. The paper is to present detailed analyses on the shield system design.
Pan, H.; Liu, X. K.; Wang, L.; Guo, X. L.; Wu, H.; Chen, A. B.; Green, M. A.
Preliminary shielding assessment for the 100 MeV proton linac (KOMAC).
The Proton Engineering Frontier Project is building the Korea Multipurpose Accelerator Complex facilities from 2002 to 2012, which consists of a high-current 100 MeV proton linear accelerator and various beam-lines. This paper provides a preliminary estimate of the shielding required for the 20 mA proton linac and the beam-dump. For an accurate information on secondary neutron production from the guiding magnet and primary heat sink of the beam dump, proton-induced 63Cu and 65Cu cross section data were evaluated and applied to shielding calculations. The required thickness of the concrete was assessed by a simple line-of-sight model for the lateral shielding of the beam-line and the full shielding of the beam dump. Monte Carlo simulations were also performed using the MCNPX code to obtain the source term and attenuation coefficients for the three-dimensional lateral shielding model of the beam-line. PMID:16381787
Lee, Young-Ouk; Cho, Y S; Chang, J
NASA Technical Reports Server (NTRS)
Building on the legacy of the Space Shuttle and other NASA space exploration initiatives, the propulsion for the Ares I First Stage will be a Shuttle derived reusable solid rocket motor. Significant progress has been made to date by the Ares First Stage Team. This brief status provides an update on the design and development of the Ares First Stage propulsion system.
Brasfield, Fred
Radiation Shielding Materials and Containers Incorporating Same
An improved radiation shielding material and storage systems for radioactive materials incorporating the same. The PYRolytic Uranium Compound (''PYRUC'') shielding material is preferably formed by heat and/or pressure treatment of a precursor material comprising microspheres of a uranium compound, such as uranium dioxide or uranium carbide, and a suitable binder. The PYRUC shielding material provides improved radiation shielding, thermal characteristic, cost and ease of use in comparison with other shielding materials. The shielding material can be used to form containment systems, container vessels, shielding structures, and containment storage areas, all of which can be used to house radioactive waste. The preferred shielding system is in the form of a container for storage, transportation, and disposal of radioactive waste. In addition, improved methods for preparing uranium dioxide and uranium carbide microspheres for use in the radiation shielding materials are also provided.
Mirsky, Steven M.; Krill, Stephen J.; and Murray, Alexander P.
Trailer shield assembly for a welding torch
NASA Technical Reports Server (NTRS)
This invention relates generally to trailer shields for gas shielded arc welding torches, and more particularly to a trailer shield assembly provided with a shield gas manifold for providing an even dispersion of shield gas to the interior of the shield assembly, which generally encloses a joint being welded and a welding trailing portion of hot welded metal. The novelty of the invention lies in providing trailer shield with a manifold tube having a plurality of openings from which shield gas is distributed. A gas manifold region ahead of the torch is also provided with shield gas from a tube to protect metal preheated by the torch. Further novelty lies in constructing portions of sides and housing and portions of side walls of the guide of stainless steel screen having a tight mesh.
Dyer, Gerald E. (inventor)
Age and petrology of alkalic postshield and rejuvenated-stage lava from Kauai, Hawaii
At the top of the Waimea Canyon Basalt on the island of Kauai, rare flows of alkalic postshield-stage hawaiite and mugearite overlie tholeiitic flows of the shield stage. These postshield-stage flows are 3.92 Ma and provide a younger limit for the age of the tholeiitic shield stage. The younger Koloa Volcanics consist of widespread alkalic rejuvenated-stage flows and vents of
David A. Clague; G. Brent Dalrymple
NASA Technical Reports Server (NTRS)
An experimental and theoretical study was conducted to develop a validated first principle analysis for predicting the jet noise reduction achieved by shielding one jet exhaust flow with a second, closely spaced, identical jet flow. A generalized fuel jet noise analytical model was formulated in which the acoustic radiation from a source jet propagates through the velocity and temperature discontinuity of the adjacent shielding jet. Input variables to the prediction procedure include jet Mach number, spacing, temperature, diameter, and source frequency. Refraction, diffraction, and reflection effects, which control the dual jet directivity pattern, are incorporated in the theory. The analysis calculates the difference in sound pressure level between the dual jet configuration and the radiation field based on superimposing two independent jet noise directivity patterns. Jet shielding was found experimentally to reduce noise levels in the common plane of the dual jet system relative to the noise generated by two independent jets.
Simonich, J. C.; Amiet, R. K.; Schlinker, R. H.
Microscopic and early stage ovarian cancers in BRCA1/2 mutation carriers: building a model for early BRCA-associated tumorigenesis
Risk-reducing salpingo-oophorectomy (RRSO) is the cornerstone of ovarian cancer prevention in BRCA1/2 mutation carriers. Occult fallopian tube and ovarian cancers have been reported in a small percentage of BRCA1/2 mutation carriers undergoing RRSO. Here, we review our single institution experience with RRSO in BRCA1/2 mutation carriers to characterize cases of microscopic cancers in these patients. At the time of RRSO, 7.9% of BRCA1 mutation carriers were diagnosed with microscopic fallopian tube or ovarian cancers and zero cases were diagnosed in BRCA2 mutation carriers. The majority of the microscopic cancers include cases that were confined to the fallopian tubes, although there were also cases involving ovaries only or peritoneal washings only. This suggests that the site of origin may be in the ovary, fallopian tube, or peritoneum for BRCA-associated serous cancers. However, an analysis of early stage (stage I and II) ovarian and fallopian tube cancers diagnosed in BRCA1/2 mutation carriers confirms that the ovary is a preferred site for tumor growth with 11 of 14 early stage cancers having a dominant ovarian mass. Overall, these data suggest that cancer initiation may occur in the ovary, fallopian tube, or peritoneum, but tumor growth and progression is favored in the ovary. We present an updated model for BRCA1/2-associated ovarian and fallopian tube carcinogenesis, which may aid in identifying improved prevention strategies for high-risk women that delay or decline RRSO.
Yates, Melinda S.; Meyer, Larissa A.; Deavers, Michael T.; Daniels, Molly S.; Keeler, Elizabeth R.; Mok, Samuel C.; Gershenson, David M.; Lu, Karen H.
NASA Technical Reports Server (NTRS)
There is a general consensus building that historically high fuel prices and greater public awareness of the emissions that result from burning fuel are going to be long-term concerns for those who design, build, and operate airliners. The possibility of saving both fuel and reducing emissions has rekindled interest in breaking very long-range airline flights into multiple stages or even adopting in-flight refueling. It is likely that staging will result in lower fuel burn, and recent published reports have suggested that the savings are substantial, particularly if the airliner is designed from the outset for this kind of operation. Given that staging runs against the design and operation historical trend, this result begs for further attention. This paper will examine the staging question, examining both analytic and numeric performance estimation methodologies to quantify the likely amount of fuel savings that can be expected and the resulting design impacts on the airliner.
Hahn, Andrew S.
Target station shielding issues at the spallation neutron source.
Recent spallation neutron source shielding activities in support of the neutron beam shutters and the hot cell walls are presented. Existing neutron beam shutters can be replaced with concrete at low power or with concrete and steel at approximately 500 kW of beam power. Potential voids in the hot cell walls are analysed to determine the impact on dose rates as a function of void size. A change in the type of shielding work is noted as the project moved from the early design stages as a 'green field' site to the current stage as a construction project nearing completion, where issues to be addressed are approaching retrofit-type analyses. PMID:16381707
Ferguson, P D; Gallmeier, F X; Iverson, E B; Popova, I I
Shielding vacuum fluctuations with graphene
NASA Astrophysics Data System (ADS)
The Casimir-Polder interaction of ground-state and excited atoms with graphene is investigated with the aim to establish whether graphene systems can be used as a shield for vacuum fluctuations of an underlying substrate. We calculate the zero-temperature Casimir-Polder potential from the reflection coefficients of graphene within the framework of the Dirac model. For both doped and undoped graphene we show limits at which graphene could be used effectively as a shield. Additional results are given for AB-stacked bilayer graphene.
Ribeiro, Sofia; Scheel, Stefan
The Embedded Self-Shielding Method
The embedded self-shielding method (ESSM) is described for computing resonance-shielded cross sections used in multigroup neutron transport calculations with the SCALE code system. The ESSM - embeds the self-shielding computation within the transport solution. The transport solution provides information for treating heterogeneous self-shielding effects, and the resulting shielded cross sections are fed back to the transport calculation. Iterations are done to obtain self-consistency. This allows self-shielded cross sections to be generated directly in the transport geometry without requiring external computation of Dancoff factors. The ESSM theory and example calculations are presented.
Williams, Mark L [ORNL; Kim, Kang Seog [ORNL
Concepts and Tests for the Remote-Controlled Dismantling of the Biological Shield and Form work of the KNK Reactor - 13425
The compact sodium-cooled nuclear reactor facility Karlsruhe (KNK), a prototype Fast Breeder, is currently in an advanced stage of dismantling. Complete dismantling is based on 10 partial licensing steps. In the frame of the 9. decommissioning permit, which is currently ongoing, the dismantling of the biological shield is foreseen. The biological shield consists of heavy reinforced concrete with built-in steel fitments, such as form-work of the reactor tank, pipe sleeves, ventilation channels, and measuring devices. Due to the activation of the inner part of the biological shield, dismantling has to be done remote-controlled. During a comprehensive basic design phase a practical dismantling strategy was developed. Necessary equipment and tools were defined. Preliminary tests revealed that hot wire plasma cutting is the most favorable cutting technology due to the geometrical boundary conditions, the varying distance between cutter and material, and the heavy concrete behind the steel form-work. The cutting devices will be operated remotely via a carrier system with an industrial manipulator. The carrier system has expandable claws to adjust to the varying diameter of the reactor shaft during dismantling progress. For design approval of this prototype development, interaction between manipulator and hot wire plasma cutting was tested in a real configuration. For the demolition of the concrete structure, an excavator with appropriate tools, such as a hydraulic hammer, was selected. Other mechanical cutting devices, such as a grinder or rope saw, were eliminated because of concrete containing steel spheres added to increase the shielding factor of the heavy concrete. Dismantling of the biological shield will be done in a ring-wise manner due to static reasons. During the demolition process, the excavator is positioned on its tripod in three concrete recesses made prior to the dismantling of the separate concrete rings. The excavator and the manipulator carrier system will be operated alternately. Main boundary condition for all the newly designed equipment is the decommissioning housing of limited space within the reactor building containment. To allow for a continuous removal of the concrete rubble, an additional opening on the lowest level of the reactor shaft will be made. All equipment and the interaction of the tools have to be tested before use in the controlled area. Therefore a full-scale model of the biological shield will be provided in a mock-up. The tests will be performed in early 2014. The dismantling of the biological shield is scheduled for 2015. (authors)
Neff, Sylvia; Graf, Anja; Petrick, Holger; Rothschmitt, Stefan [WAK Rueckbau- und Entsorgungs- GmbH, P.O.Box 12 63, 76339 Eggenstein- Leopoldshafen (Germany)] [WAK Rueckbau- und Entsorgungs- GmbH, P.O.Box 12 63, 76339 Eggenstein- Leopoldshafen (Germany); Klute, Stefan [Siempelkamp Nukleartechnik GmbH, Am Taubenfeld 25/1, 69123 Heidelberg (Germany)] [Siempelkamp Nukleartechnik GmbH, Am Taubenfeld 25/1, 69123 Heidelberg (Germany); Stanke, Dieter [Siempelkamp NIS Ingenieurgesellschaft mbH, Industriestrasse 13, 63755 Alzenau (Germany)] [Siempelkamp NIS Ingenieurgesellschaft mbH, Industriestrasse 13, 63755 Alzenau (Germany)
Accelerator shield design of KIPT neutron source facility
Argonne National Laboratory (ANL) of the United States and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the design development of a neutron source facility at KIPT utilizing an electron-accelerator-driven subcritical assembly. Electron beam power is 100 kW, using 100 MeV electrons. The facility is designed to perform basic and applied nuclear research, produce medical isotopes, and train young nuclear specialists. The biological shield of the accelerator building is designed to reduce the biological dose to less than 0.5-mrem/hr during operation. The main source of the biological dose is the photons and the neutrons generated by interactions of leaked electrons from the electron gun and accelerator sections with the surrounding concrete and accelerator materials. The Monte Carlo code MCNPX serves as the calculation tool for the shield design, due to its capability to transport electrons, photons, and neutrons coupled problems. The direct photon dose can be tallied by MCNPX calculation, starting with the leaked electrons. However, it is difficult to accurately tally the neutron dose directly from the leaked electrons. The neutron yield per electron from the interactions with the surrounding components is less than 0.01 neutron per electron. This causes difficulties for Monte Carlo analyses and consumes tremendous computation time for tallying with acceptable statistics the neutron dose outside the shield boundary. To avoid these difficulties, the SOURCE and TALLYX user subroutines of MCNPX were developed for the study. The generated neutrons are banked, together with all related parameters, for a subsequent MCNPX calculation to obtain the neutron and secondary photon doses. The weight windows variance reduction technique is utilized for both neutron and photon dose calculations. Two shielding materials, i.e., heavy concrete and ordinary concrete, were considered for the shield design. The main goal is to maintain the total dose outside the shield boundary at less than 0.5-mrem/hr. The shield configuration and parameters of the accelerator building have been determined and are presented in this paper. (authors)
Zhong, Z.; Gohar, Y. [Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States)] [Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States)
Decontaminating lead bricks and shielding
Lead used for shielding is often surface contaminated with radioisotopes and is therefore a RCRA D008 mixed waste. The technology-based standard for treatment is macroencapsulation. However, decontaminating and recycling the clean lead is a more attractive solution. Los Alamos National Laboratory decontaminates material and equipment contaminated with radioisotopes. Decontaminating lead poses special problems because of the RCRA hazard classification and
Decontaminating lead bricks and shielding
Lead used for shielding is often surface contaminated with radioisotopes and is therefore a RCRA D008 mixed waste. The technology-based standard for treatment is macroencapsulation. However, decontaminating and recycling the clean lead is a more attractive solution. Los Alamos National Laboratory decontaminates material and equipment contaminated with radioisotopes. Decontaminating lead poses special problems because of the RCRA hazard classification and
Improved space radiation shielding methods
NASA Technical Reports Server (NTRS)
The computing software that was used to perform the charged particle radiation transport analysis and shielding design for the Mariner Jupiter/Saturn 1977 spacecraft is described. Electron fluences, energy spectra and dose rates obtained with this software are presented and compared with independent computer calculations.
Davis, H. S.; Jordan, T. M.
Heat shield reduces water loss.
A heat shield covered by polyvinyl chloride film greatly reduced insensible water loss and radiant energy requirements in 12 preterm infants on a radiant cradle. Measured transmittance of radiant energy emitted by the radiant heater was impeded minimally by various thin film plastics but was blocked significantly by Perspex. Images Figure
Fitch, C W; Korones, S B
A Large Superconducting Magnetic Shield.
National Technical Information Service (NTIS)
A large superconducting magnetic shield was designed and constructed to provide a low intensity field in a temperature controllable volume approximately 30 cm (12 in) long by 10.2 cm (4 in) in diameter. Design, construction and operating techniques are di...
R. H. Lundsten, J. F. Scarzello
Hypervelocity impact on shielded plates
A ballistic limit equation for hypervelocity impact on thin plates is derived analytically. This equation applies to cases of impulsive impact on a plate that is protected by a multi-shock shield, and it is valid in the range of velocity above 6 km\\/s. Experimental tests were conducted at the NASA Johnson Space Center on square aluminum plates. Comparing the center
James P. Smith
Material Effectiveness for Radiation Shielding
NASA Technical Reports Server (NTRS)
Materials with a smaller mean atomic mass, such as lithium (Li) hydride and polyethylene, make the best radiation shields for astronauts. The materials have a higher density of nuclei and are better able to block incoming radiation. Also, they tend to produce fewer and less dangerous secondary particles after impact with incoming radiation.
D0 Silicon Upgrade: Muon Shield Conceptual Design Report
The nominal overall dimensions are 71-inch high x 71-inch wide x 144-inch long and has a 25-inch square hole throughout. The shield consists of three different materials, steel (inner most section), polycarbonate (central section) and lead (outer most section). The material thicknesses are, steel=15-inch, poly=6-inch and lead=2-inch. The estimated weight is {approx}69 tons. The shield is centered about the Tev beam line and the 25-inch square hole provides clearance to the low Beta quad, which is nominally 20-inch square. During beamline operation, the shield is in contact with Samus magnet core at the detector end and with the Main Ring shield wall on the MR side (with some small clearance {approx}2-inch-3-inch). The need for the clearance will be discussed later. The shield support structure consists steel structural members appropriately sized for loads encountered in the design. The structure must not only support the shield but, must be designed for rolling the entire assembly into position in the collision hall. It must provide for cylinders to lift the assembly, Hilman rollers and also connections for moving the entire assembly. The movement is considered to be similar to that with which the calorimeters were moved from the clean room to the sidewalk staging area, i.e. hydraulic cylinder and chain (see dwg. 3740.000-ME294017,3 sheets). This method will be used for the East to West motion and a hydraulic scheme will be used for any North-South motion. Since the shield is 144-inch long and the sidewalk structural support is {approx}96-inch, there is a section of the shield that is cantilevered (48-inch). Further, the EF toroid must open {approx}40+ inch for access to the detector during operations and this requires that the shield or some part of it must also move. This conceptual design suggests that the shield be designed in two pieces axially. These two pieces are identical in cross section but, the lengths are divided into 48-inch nearest EF and 96-inch nearest the MR tunnel. The 96-inch section is designed to clam shell, i.e. split vertically along the beam line, with each half moving {approx}36-inch East/West. The opening created with this motion (72-inch) is 1-inch greater than the width of the shield, 71 If. Now the forward section can be moved, North/South, within the opened end section, a full 48-inch. The forward section will be support at one end by the basic shield support structure and at the EF end by a member welded to EF. Rails will be extended from the basic structure to EF and these rails will be collapsible within the basic structure. The shield sections will be mounted on Hilman rollers and all motions will be provided by hydraulic cylinders.
Stredde, Herman J.; /Fermilab
Basaltic Shield Volcanoes: A Quantitative Tool for Characterizing Flow Field Morphometry
NASA Astrophysics Data System (ADS)
Young basaltic shields display morphologies unique from older shields that have undergone magmatic evolution. We have tested the validity of differentiating basaltic shields at different stages of magmatic evolution through analysis of their slope frequency distributions. Slopes are the irregular surface expressions of the processes that have formed the landscape. Therefore, unique slope distributions can be used to identify regions that have undergone unique formational processes. Young shields form a broad, gently sloping structure composed of long, overlapping lava flows. These flows are often erupted from a central source vent region. Throughout the magmatic evolution of a shield volcano, the erupted lavas gradually become more silicic. As the erupted lavas become more viscous, flow lengths decrease causing slopes to increase near the summit. Late stage shield volcanism is typified by eruption of lavas from numerous vents producing steep sided cones that are superimposed on the shield's flanks. As a shield volcano ages, its morphometry evolves due to the changing lava flow emplacement conditions. Slope analyses should detect the differing emplacement conditions that exist between young and old shields as unique slope frequency distributions. We have conducted slope frequency studies on the USGS, 10 m Digital Elevation Models (DEMs) for the Hawaiian shields Mauna Kea and Mauna Loa. Slopes were calculated from a complete Hawaiian DEM, mosaiced in ArcView GIS 3.2 by ESRI (Environmental Systems Research Institute, Inc.). A slope frequency plot, or histogram, is produced for each shield. Mauna Loa displays a gaussian distribution of slopes centered at 15 degrees while the older shield, Mauna Kea, displays a gaussian distribution that is skewed towards higher slopes centered at 21 degrees. The unique slope signatures of the two volcanoes highlight the unique flow emplacement conditions for shields at different stages of magmatic evolution. Slope frequency distribution analyses could also be capable of identifying the unique flow field emplacement processes that form Flood- and Plains-style basaltic provinces. If so, these studies can be used to further characterize basaltic provinces on any planetary surface for which reliable topographic data exists.
Bleacher, J. E.; Greeley, R.
Shielding design for a PET imaging suite: a case study.
The introduction of positron emission tomography into the clinical environment presents the medical health physicist with another challenge to his/her shielding acumen. On one hand, elaborate models can be employed, but most of these are beyond the resources possessed by most institutions. On the other hand, one could perform the analysis using simplifying assumptions (e.g., point source geometry, with or without build-up). This kind of approach would likely overestimate the shielding requirements. Such over-design is not ALARA. In fact, over-design could place such tight engineering or cost constraints on a project as to make it untenable. Recently, this designer was faced with the need to design a PET imaging suite with both engineering and time constraints. This paper describes an approach using resources readily available to medical health physicists. By using the dimensions of the bottle manikin (BOMAB) phantom as a guide, a human-form source was developed. Combined with a point-kernel shielding code, the exposure environment was readily modeled and shielding recommendations developed. In addition, to validate the model, results from preoperational instrument surveys and integrating dosimeters are discussed. PMID:12751198
Meth�, Brian M
Predictions for Radiation Shielding Materials
NASA Technical Reports Server (NTRS)
Radiation from galactic cosmic rays (GCR) and solar particle events (SPE) is a serious hazard to humans and electronic instruments during space travel, particularly on prolonged missions outside the Earth s magnetic fields. Galactic cosmic radiation (GCR) is composed of approx. 98% nucleons and approx. 2% electrons and positrons. Although cosmic ray heavy ions are 1-2% of the fluence, these energetic heavy nuclei (HZE) contribute 50% of the long-term dose. These unusually high specific ionizations pose a significant health hazard acting as carcinogens and also causing microelectronics damage inside spacecraft and high-flying aircraft. These HZE ions are of concern for radiation protection and radiation shielding technology, because gross rearrangements and mutations and deletions in DNA are expected. Calculations have shown that HZE particles have a strong preference for interaction with light nuclei. The best shield for this radiation would be liquid hydrogen, which is totally impractical. For this reason, hydrogen-containing polymers make the most effective practical shields. Shielding is required during missions in Earth orbit and possibly for frequent flying at high altitude because of the broad GCR spectrum and during a passage into deep space and LunarMars habitation because of the protracted exposure encountered on a long space mission. An additional hazard comes from solar particle events (SPEs) which are mostly energetic protons that can produce heavy ion secondaries as well as neutrons in materials. These events occur at unpredictable times and can deliver a potentially lethal dose within several hours to an unshielded human. Radiation protection for humans requires safety in short-term missions and maintaining career exposure limits within acceptable levels on future long-term exploration missions. The selection of shield materials can alter the protection of humans by an order of magnitude. If improperly selected, shielding materials can actually increase radiation damage due to penetration properties and nuclear fragmentation. Protecting space-borne microelectronics from single event upsets (SEUs) by transmitted radiation will benefit system reliability and system design cost by using optimal shield materials. Long-term missions on the surface of the Moon or Mars will require the construction of habitats to protect humans during their stay. One approach to the construction is to make structural materials from lunar or Martian regolith using a polymeric material as a binder. The hydrogen-containing polymers are considerably more effective for radiation protection than the regolith, but the combination minimizes the amount of polymer to be transported. We have made composites of simulated lunar regolith with two different polymers, LaRC-SI, a high-performance polyimide thermoset, and polyethylene, a thermoplastic.
Kiefer, Richard L.
Rotary stripper for shielded and unshielded FCC
NASA Technical Reports Server (NTRS)
Rotary stripper removes narrow strips of insulation and shielding to any desired depth. Unshielded cables are stripped on both sides with one stroke, shielded cables are stripped in steps of different depths.
Angele, W.; Chambers, C. M.
Electromagnetic coupling through multiconductor cable shields
This paper discusses two approaches to the determination of the distribution of source terms of a shielded multiconductor cable due to electromagnetic coupling through the shield. Comparisons are made of the results of some of these calculations with available data.
Tigner, T.E.; Frederick, D.; Setty, P.N.; Sutton, R.W.
Effect of cosmic-ray shielding on the ultraweak bioluminescence emitted by cultures of Escherichia coli
Neither the growth of Escherichia coli nor its associated luminescence was significantly affected when cultures were shielded from the soft component of cosmic rays. The study included experiments in which the cultures were shielded intermittently during their two periods of luminescence emission and experiments in which the cultures were continuously shielded throughout their entire growth cycle. These results do not support previous suggestions that the ultraweak bioluminescences from living organisms might be cosmic-ray-excited fluorescences induced in certain biological molecules synthesized during the various stages of growth.
Tilbury, R.N.; Quickenden, T.I.
Shielding and grounding in large detectors
Prevention of electromagnetic interference (EMI), or ``noise pickup,`` is an important design aspect in large detectors in accelerator environments. Shielding effectiveness as a function of shield thickness and conductivity vs the type and frequency of the interference field is described. Noise induced in transmission lines by ground loop driven currents in the shield is evaluated and the importance of low shield resistance is emphasized. Some measures for prevention of ground loops and isolation of detector-readout systems are discussed.
Radeka, V.
Thermal Degradation of Lead Monoxide Filled Polymer Composite Radiation Shields
Lead monoxide filled Isophthalate resin particulate polymer composites were prepared with different filler concentrations and investigated for physical, thermal, mechanical and gamma radiation shielding characteristics. This paper discusses about the thermo gravimetric analysis of the composites done to understand their thermal properties especially the effect of filler concentration on the thermal stability and degradation rate of composites. Pristine polymer exhibits single stage degradation whereas filled composites exhibit two stage degradation processes. Further, the IDT values as well as degradation rates decrease with the increased filler content in the composite.
Harish, V. [Department of Physics, Government First Grade College, Shivamogga-577201 (India); Nagaiah, N. [Department of Physics, Bangalore University, Jnanabharati, Bangalore-560056 (India)
Some observations about shielding extremely low-frequency magnetic fields by finite width shields
Shielding of extremely low-frequency magnetic fields is limited by fields penetrating through imperfect material and leakage around the edges of shields which do not completely enclose the shielded region. The latter effect, more specifically the effect of source geometry and shield type on leakage, is the subject of this work. Particular attention is paid to elementary cylindrical dipole sources since
Robert G. Olsen; Pablo Moreno
Lightning Shielding of Plastic Telephone Cable
Data are presented on the surge characteristics of various types and combinations of metals when applied as a shield for buried telephone cables. Surge currents were applied to the shield of 500-foot lengths of cable and the potentials developed between the shield and conductors were measured at selected points along the cable length in order to determine relative susceptibility to
E. Fisher; W. Bishop
13C Chemical Shieldings in Solids
Analogous to the importance of 13C isotropic shieldings for chemical analysis of liquids with nuclear magnetic resonance spectroscopy, 13C chemical shielding anisotropies are proving to be valuable in the characterization of solids. Specifically, molecular geometry is revealed by the full shielding anisotropy and molecular motion may be characterized by changes in the powder pattern. In particular, the principal components of
T. M. Duncan
Shielding techniques tackle EMI excesses. V - EMI shielding
NASA Astrophysics Data System (ADS)
The utilization of shielding gaskets in EMI design is presented in terms of seam design, gasket design, groove design, and fastener spacing. The main function of seam design is to minimize the coupling efficiency of a seam, and for effective shielding, seam design should include mating surfaces which are as flat as possible, and a flange width at least five times the maximum anticipated separation between mating surfaces. Seam surface contact with a gasket should be firm, continuous, and uniform. Gasket height, closure pressure, and compression set as a function of the applied pressure parameters are determined using compression/deflection curves. Environmental seal requirements are given and the most common materials used are neoprene, silicone, butadiene-acrylonitrile, and natural rubber. Groove design is also discussed, considering gasket heights and cross-sectional areas. Finally, fastener spacing is considered, by examining deflection as a percentage of gasket height.
Grant, P.
Deep Space Environment and Shielding
NASA Astrophysics Data System (ADS)
Mission scenarios outside the Earth's protective magnetic shield are being studied. Included are high usage assets in the near-Earth environment for casual trips, for research, for commercial and for operational platforms, in which career exposures will be multimission determined over the astronaut's lifetime. In addition, the exploration beyond these near Earth operational platforms will include single missions of long duration to planets, asteroids, and planetary satellites. The interplanetary environment is evaluated using convective diffusion theory. Local induced environments for each celestial body are modeled by using results from recent targeted spacecraft studies, and integrated into the design environments. Design scenarios are then evaluated for these missions. The underlying assumptions in deriving the model environments and their impact on mission exposures with various shield materials will be discussed.
Wilson, J. W.; Nealy, J. E.; de Angelis, G.; Clowdsley, M. S.; Badavi, F. F.
Thermally isolated deployable shield for spacecraft
NASA Technical Reports Server (NTRS)
A thermally isolated deployable shield for spacecraft is provided utilizing a plurality of lattice panels stowable generally against the craft and deployable to some fixed distance from the craft. The lattice panels are formed from replaceable shield panels affixed to lattice structures. The lattice panels generally encircle the craft providing 360 degree coverage therearound. Actuation means are provided from translating the shield radially outward from the craft and thermally isolating the shield from the craft. The lattice panels are relatively flexible, allowing the shield to deploy to variable diameters while retaining uniform curvature thereof. Restraining means are provided for holding the shield relatively tight in its stowed configuration. Close-out assemblies provide light sealing and protection of the annular spaces between the deployed shield and the crafts end structure.
Redmon, John W., Jr. (inventor); Miller, Andre E. (inventor); Lawson, Bobby E. (inventor); Cobb, William E. (inventor)
Design of magnets inside cylindrical superconducting shields
NASA Technical Reports Server (NTRS)
The design of magnets inside closed, cylindrical, superconducting shields is discussed. The Green function is given for the magnetic vector potential for cylindrically symmetric currents inside such a shield. The magnetic field everywhere inside the shield can be obtained from this function, which includes the effects of the induced shield currents exactly. The field is given for a thin solenoid as an example and the convergence of the series solution for this case is discussed. The shield can significantly reduce the strength and improve the homogeneity of a magnet. The improvement in homogeneity is of particular importance in the design of correction coils. These effects, and the maximum field on the shield, are examined for a typical solenoid. The results given are also useful, although not exact, for long shields with one or two open ends.
Rigby, K. W.
Mats and fabrics for electromagnetic interference shielding
NASA Astrophysics Data System (ADS)
Fabrics (with continuous electrically conductive fibers) are more effective than mats (with discontinuous conductive fibers) for electromagnetic interference shielding. Conductive fibers in the form of metal-coated polymer fibers or metal-coated carbon fibers are more effective than those in the form of bare carbon fibers. The highest shielding effectiveness of 53 dB at 1.0 GHz was attained by a metal-coated polymer fabric. The shielding is due mainly to reflection. A higher shielding effectiveness correlates with a higher reflectivity and a lower electrical resistivity. Both shielding effectiveness and reflectivity decrease with increasing frequency from 300 kHz to 1.5 GHz. The shielding effectiveness increases with thickness, as shown for bare carbon fiber mats. A nickel-coated carbon fiber mat of areal weight 9 g/m2 is similar to a bare carbon fiber mat of areal weight 17 g/m2 in shielding effectiveness.
Kim, Taejin; Chung, D. D. L.
NASA Technical Reports Server (NTRS)
The SNAP 8 developmental reactor lithium hydride shield was examined after being irradiated for over 7000 hours at relatively low temperature. A crack was located in the seam weld of the containment vessel, probably the result of hot short cracking under thermal stress. The LiH was visually examined at two locations and its appearance was typical of low temperature irradiated LiH. The adherence of the chrome oxide emittance coating was found to be excellent.
Mason, D. G.; Mccurnin, W. R.
Shielding calculations for Inshas cyclotron
NASA Astrophysics Data System (ADS)
Methods used in shielding calculations for the cyclotron vault and experimental rooms of Egypt's first cyclotron laboratory to be erected at the premises of the Nuclear Research Center, Atomic Energy Authority (Inshas) are discussed. Use is made of the removal diffusion theory and of the techniques presented in NCRP-51, Wall and ceiling dimensions are estimated based on radiation protection norms given in the ICRP-60 as issued in 1991.
Comsan, M. N. H.
Steam generator hand hole shielding.
Seabrook Station is an 1198 MWE Pressurized Water Reactor (PWR) that began commercial operation in 1990. Expensive and dose intensive Steam Generator Replacement Projects among PWR operators have led to an increase in steam generator preventative maintenance. Most of this preventative maintenance is performed through access ports in the shell of the steam generator just above the tube sheet known as secondary side hand holes. Secondary side work activities performed through the hand holes are typically performed without the shielding benefit of water in the secondary side of the steam generator. An increase in cleaning and inspection work scope has led to an increase in dose attributed to steam generator secondary side maintenance. This increased work scope and the station goal of maintaining personnel radiation dose ALARA led to the development of the shielding concept described in this article. This shield design saved an estimated 2.5 person-rem (25 person-Smv) the first time it was deployed and is expected to save an additional 50 person-rem (500 person-mSv) over the remaining life of the plant. PMID:10770158
Cox, W E
Photonic Bandgap (PBG) Shielding Technology
NASA Technical Reports Server (NTRS)
Photonic Bandgap (PBG) shielding technology is a new approach to designing electromagnetic shielding materials for mitigating Electromagnetic Interference (EM!) with small, light-weight shielding materials. It focuses on ground planes of printed wiring boards (PWBs), rather than on components. Modem PSG materials also are emerging based on planar materials, in place of earlier, bulkier, 3-dimensional PBG structures. Planar PBG designs especially show great promise in mitigating and suppressing EMI and crosstalk for aerospace designs, such as needed for NASA's Constellation Program, for returning humans to the moon and for use by our first human visitors traveling to and from Mars. Photonic Bandgap (PBG) materials are also known as artificial dielectrics, meta-materials, and photonic crystals. General PBG materials are fundamentally periodic slow-wave structures in I, 2, or 3 dimensions. By adjusting the choice of structure periodicities in terms of size and recurring structure spacings, multiple scatterings of surface waves can be created that act as a forbidden energy gap (i.e., a range of frequencies) over which nominally-conductive metallic conductors cease to be a conductor and become dielectrics. Equivalently, PBG materials can be regarded as giving rise to forbidden energy gaps in metals without chemical doping, analogous to electron bandgap properties that previously gave rise to the modem semiconductor industry 60 years ago. Electromagnetic waves cannot propagate over bandgap regions that are created with PBG materials, that is, over frequencies for which a bandgap is artificially created through introducing periodic defects
Bastin, Gary L.
Multi-stage mountain building vs. relative plate motions in the Betic Cordillera deduced from integrated microstructural and petrological analysis of porphyroblast inclusion trails
NASA Astrophysics Data System (ADS)
The tectonic evolution of the Betic Cordillera has been investigated through integrated microstructural and petrological analysis of 93 samples of garnetiferous Grt � Cld � Plg � Ky � St phengite schists from its lowermost allochthon, the Nevado-Filabride Domain. Porphyroblast inclusion trails in these samples exhibit well-developed preferred vertical and horizontal orientations and truncational relationships. These features indicate a complex history of multiple crenulation cleavage development during alternating contractional and gravity-induced deformations. Associated Foliation-Intersection Axes preserved in porphyroblasts (FIA) were determined separately for 2 groups of samples using the "asymmetry technique" (Bell et al., 1995) and the "FitPitch" method (Aerden, 2003), respectively. Broadly consistent results establish a succession of 4 FIA sets with specific trends, which from the oldest to the youngest FIA set are: NE-SW (FIA set 1), NW-SE (FIA set 2), W-E (FIA set 3) and NNW-SSE (FIA set 4). This trend sequence is also reflected in the orientations of successive fold generations and associated lineations. More remarkably, the FIA-trend sequence mimics known changes in the plate motions of Africa and Adria relative to Iberia in the 50-10 Ma interval. This is also the time span indicated by published radiometric ages. Garnet-isopleth thermobarometry applied to selected samples and compositional zoning of garnets indicate that the earliest 3 FIA sets formed along a prograde metamorphic path from ca. 5 kb/500 �C to 10 kb/550 �C, whereas the latest stages of FIA set 3 and FIA set 4 developed during exhumation. Exhumation involved a period of heterogeneous reheating that was spatially and temporally linked to emplacement of the overlying Alpujarride Complex.
Aerden, D. G. A. M.; Bell, T. H.; Puga, E.; Sayab, M.; Lozano, J. A.; Diaz de Federico, A.
Recommendations for a Static Cosmic Ray Shield for Enriched Germanium Detectors
This document provides a detailed study of cost and materials that could be used to shield the detector material of the international Tonne-scale germanium neutrinoless double-beta decay experiment from hadronic particles from cosmic ray showers at the Earth's surface. This work was motivated by the need for a shield that minimizes activation of the enriched germanium during storage; in particular, when the detector material is being worked on at the detector manufacturer's facility. This work considers two options for shielding the detector material from cosmic ray particles. One option is to use a pre-existing structure already located near the detector manufacturer, such as Canberra Industries in Meriden, Connecticut. The other option is to build a shield onsite at a detector manufacturer's site. This paper presents a cost and efficiency analysis of such construction.
Aguayo Navarrete, Estanislao; Orrell, John L.; Ankney, Austin S.; Berguson, Timothy J.
Heat-shield design for glovebox applications.
Heat shields can often be used in place of insulation materials as an effective means of insulating glovebox furnace vessels. If used properly, shields can accomplish two important objectives: thermal insulation of the vessel to maintain a desired process temperature and protection of the glovebox, equipment, and user. A heat-shield assembly can be described as an arrangement of thin, properly-spaced, metal sheets that reduce radiation heat transfer. The main problem encountered in the design of a heat shield assembly is choosing the number of shields. In determining the heat transfer characteristics of a heat-shield assembly, a number of factors must be taken into consideration. The glovebox or outside environment, material properties, geometry, and operating temperature all have varying effects on the expected results. A simple method, for planar-horizontal and cylindrical-vertical shields, allowing the approximation of the outermost shield temperature, the practical number of shields, and the net heat-transfer rate will be presented. Methods used in the fabrication of heat-shield assemblies will also be discussed.
Frigo, A. A.
The Feasibility of Multipole Electrostatic Radiation Shielding
NASA Technical Reports Server (NTRS)
Although passive shielding appears to be the only workable solution for galactic cosmic radiation (GCR), active shielding may play an important augmenting role to control the dose from solar particle events (SPEs). It has been noted that, to meet the guidelines of NCRP Report No. 98 through the six SPEs of 1989, a crew member would need roughly double the passive shielding that is necessary to control the GCR dose . This would dramatically increase spacecraft mass, and so it has been proposed that a small but more heavily shielded storm shelter may be used to protect the crew during SPEs. Since a gradual SPE may last 5 or more days, staying in a storm shelter may be psychologically and physiologically distressing to the crew. Storm shelters do not provide shielding for the spacecraft itself against the SPE radiation, and radiation damage to critical electronics may result in loss of mission and life. Single-event effects during the radiation storm may require quick crew response to maintain the integrity of the spacecraft, and confining the crew to a storm shelter prohibits their attending to the spacecraft at the precise time when that attention is needed the most. Active shielding cannot protect against GCR because the particle energies are too high. Although lower energy particles are easier to stop in a passive shield, such shielding is more satisfactory against GCR than against SPE radiation because of the tremendous difference in their initial fluences. Even a small fraction of the SPE fluence penetrating the passive shielding may result in an unacceptably high dose. Active shielding is more effective than passive shielding against SPE radiation because it offers 100% shielding effectiveness up to the cutoff energy, and significant shielding effectiveness beyond the cutoff as well.
Metzger, Philip T.; Lane, John E.; Youngquist, Robert C.
Exploratory Environmental Tests of Several Heat Shields
NASA Technical Reports Server (NTRS)
Exploratory tests have been conducted with several conceptual radiative heat shields of composite construction. Measured transient temperature distributions were obtained for a graphite heat shield without insulation and with three types of insulating materials, and for a metal multipost heat shield, at surface temperatures of approximately 2,000 F and 1,450 F, respectively, by use of a radiant-heat facility. The graphite configurations suffered loss of surface material under repeated irradiation. Temperature distribution calculated for the metal heat shield by a numerical procedure was in good agreement with measured data. Environmental survival tests of the graphite heat shield without insulation, an insulated multipost heat shield, and a stainless-steel-tile heat shield were made at temperatures of 2,000 F and dynamic pressures of approximately 6,000 lb/sq ft, provided by an ethylene-heated jet operating at a Mach number of 2.0 and sea-level conditions. The graphite heat shield survived the simulated aerodynamic heating and pressure loading. A problem area exists in the design and materials for heat-resistant fasteners between the graphite shield and the base structure. The insulated multipost heat shield was found to be superior to the stainless-steel-tile heat shield in retarding heat flow. Over-lapped face-plate joints and surface smoothness of the insulated multi- post heat shield were not adversely affected by the test environment. The graphite heat shield without insulation survived tests made in the acoustic environment of a large air jet. This acoustic environment is random in frequency and has an overall noise level of 160 decibels.
Goodman, George P.; Betts, John, Jr.
EMC effects of the lightning protection system: shielding properties of the roof-grid
A suitable set of parameters is used to evaluate the shielding performance of the roof-grid constituted by a mesh of conductors, electrically interconnected, laying on top of buildings with a large-area roof. The influence of the roof-grid on the electromagnetic field inside the building due to a direct lightning strike is shown. The values of the electromotive force induced in
S. Cristina; A. Orlandi
Seismic analysis of the mirror fusion test facility shielding vault
This report presents a seismic analysis of the vault in Building 431 at Lawrence Livermore National Laboratory which houses the mirror Fusion Test Facility. The shielding vault structure is approximately 120 ft long by 80 ft wide and is constructed of concrete blocks approximately 7 x 7 x 7 ft. The north and south walls are approximately 53 ft high and the east wall is approximately 29 ft high. These walls are supported on a monolithic concrete foundation that surrounds a 21-ft deep open pit. Since the 53-ft walls appeared to present the greatest seismic problem they were the first investigated.
Gabrielsen, B.L.; Tsai, K.
A&M. Shielded locomotive (TAN807). Parked and inactive on track west ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
A&M. Shielded locomotive (TAN-807). Parked and inactive on track west of A&M building. Camera facing northeast. Date: March 2004. INEEL negative no. HD-39-10-1 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
Additional adjoint Monte Carlo studies of the shielding of concrete structures against initial gamma radiation
The adjoint Monte Carlo method previously developed by MAGI has been applied to the calculation of initial radiation dose due to air secondary gamma rays and fission product gamma rays at detector points within buildings for a wide variety of problems. These provide an in-depth survey of structure shielding effects as well as many new benchmark problems for matching by
M. Beer; M. O. Cohen
LOFT, TAN630. Interior detail of shield door at end of ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
LOFT, TAN-630. Interior detail of shield door at end of corridor on ground level and west of control room. Separates control building from hangar. Camera facing west. Date: May 2004. INEEL negative no. HD-39-14-2 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
LOFT. Contextual view of south side of shielded roadway (TAN719). ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
LOFT. Contextual view of south side of shielded roadway (TAN-719). Loft containment building (TAN-650) and stack at left edge of view. Camera facing northwest. Date: March 2004. INEEL negative no. HD-39-3-1 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
76. ARAII. After SL1 explosion, operators shielded crane cab try ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
76. ARA-II. After SL-1 explosion, operators shielded crane cab try to open door of SL-1 tank building. January 6, 1961. Ineel photo no. 61-80. Photographer: Holmes. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID
Optimation of cooled shields in insulations
NASA Technical Reports Server (NTRS)
A method to optimize the location, temperature, and heat dissipation rate of each cooled shield inside an insulation layer was developed. The method is based on the minimization of the entropy production rate which is proportional to the heat leak across the insulation. It is shown that the maximum number of shields to be used in most practical applications is three. However, cooled shields are useful only at low values of the overall, cold wall to hot wall absolute temperature ratio. The performance of the insulation system is relatively insensitive to deviations from the optimum values of the temperature and location of the cooling shields. Design curves for rapid estimates of the locations and temperatures of cooling shields in various types of insulations, and an equation for calculating the cooling loads for the shields are presented.
Chato, J. C.; Khodadadi, J. M.; Seyed-Yagoobi, J.
Miniature, shielded electrical connector with strain relief
NASA Technical Reports Server (NTRS)
An electrical connector assembly includes a wire bundle having at least one wire with a metal shield surrounding at least a portion of the wire. The shield has an end portion and provides electromagnetic interference protection to the wire. A backshell includes a body and a cover secured to the body together defining an internal cavity with the wire at least partially arranged within the cavity. The backshell provides EMI protection for the portion of the wire bundle not covered by the shield. The backshell includes a hole in a wall of either the body or the cover with the end portion of the shield extending through the hole. The clamp is secured about the body and the cover with the end portion of the shield arranged between the clamp and the backshell grounding the shield to the backshell. The clamp forces the backshell into engagement with the wire bundle to provide strain relief for the wire bundle.
Diep, Chuong H. (Inventor)
A procedure for multi-criteria selection of building assemblies
During some of the different building design stages, typical construction materials\\/components are often grouped together to form what is called building assemblies. One of the most important tasks in the design development stage of building design is the selection of the appropriate building assemblies to be used in the various elements of the building, e.g. walls, roofs, floors and so
K. Nassar; Walid Thabet; Yvan Beliveau
Ballistic limit equations for spacecraft shielding
This paper provides equations describing the ballistic performance capability of meteoroid\\/orbital debris (M\\/OD) shield systems employed on the International Space Station (ISS). Hypervelocity impact (HVI) tests and analysis were used in developing the semi-empirical ballistic limit equations (BLE). A description of each type of shield system, HVI tests and analysis performed to assess shield performance, and ballistic limit equations that
Eric L. Christiansen; Justin H. Kerr
Shielding analyses for repetitive high energy pulsed power accelerators
NASA Astrophysics Data System (ADS)
Sandia National Laboratories (SNL) designs, tests and operates a variety of accelerators that generate large amounts of high energy Bremsstrahlung radiation over an extended time. Typically, groups of similar accelerators are housed in a large building that is inaccessible to the general public. To facilitate independent operation of each accelerator, test cells are constructed around each accelerator to shield it from the radiation workers occupying surrounding test cells and work-areas. These test cells, about 9 ft. high, are constructed of high density concrete block walls that provide direct radiation shielding. Above the target areas (radiation sources), lead or steel plates are used to minimize skyshine radiation. Space, accessibility and cost considerations impose certain restrictions on the design of these test cells. SNL Health Physics division is tasked to evaluate the adequacy of each test cell design and compare resultant dose rates with the design criteria stated in DOE Order 5480.11. In response, SNL Health Physics has undertaken an intensive effort to assess existing radiation shielding codes and compare their predictions against measured dose rates. This paper provides a summary of the effort and its results.
Jow, H. N.; Rao, D. V.
Fan broadband noise shielding for over-wing engines
NASA Astrophysics Data System (ADS)
Increasingly demanding community noise targets are promoting noise performance ever higher on the list of airliner design drivers. In response, significant noise reductions are being made, though at a declining rate�it appears that a whole airframe approach is now needed to achieve significant further gains. As a possible step in this direction, over-wing engine installations are considered here, which use the airframe itself as a noise shield. The paper is the account of an experimental investigation of the comparative shielding performances of a range of relative engine positions on such a layout. Using the statistical modelling technique Kriging, we build an approximation of the noise shielding metric as a function of the position of the engines above the wing�this can serve as the input to multi-disciplinary design trade-off studies. We then compare the results found with the results of applying simple half-barrier diffraction theory to the same problem. We conclude that the latter could be considered as a first order, conceptual design tool, though it misses certain features of the design merit landscape identified by the experiment presented here.
Powell, Stephen; S�bester, Andr�s; Joseph, Phillip
THEMIS discovers holes in Earth's solar shield
This animation shows the latest findings from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission. Earth's magnetic field; which shields our planet from severe ...
The ORNL-SNAP shielding program
NASA Technical Reports Server (NTRS)
The effort in the ORNL-SNAP shielding program is directed toward the development and verification of computer codes using numerical solutions to the transport equation for the design of optimized radiation shields for SNAP power systems. A brief discussion is given for the major areas of the SNAP shielding program, which are cross-section development, transport code development, and integral experiments. Detailed results are presented for the integral experiments utilizing the TSF-SNAP reactor. Calculated results are compared with experiments for neutron and gamma-ray spectra from the bare reactor and as transmitted through slab shields.
Mynatt, F. R.; Clifford, C. E.; Muckenthaler, F. J.; Gritzner, M. L.
Accelerator magnet designs using superconducting magnetic shields
Superconducting dipoles and quadrupoles for existing accelerators have a coil surrounded by an iron shield. The shield limits the fringe field of the magnet while having minimal effect on the field shape and providing a small enhancement of the field strength. Shields using superconducting materials can be thinner and lighter and will not experience the potential of a large de-centering force. Boundary conditions for these materials, material properties, mechanical force considerations, cryostat considerations and some possible geometrical configurations for superconducting shields will be described. 7 refs., 3 figs., 3 tabs.
Brown, B.C.
Shielding for thermoacoustic tomography with RF excitation
NASA Astrophysics Data System (ADS)
Radiofrequency (RF) pulses used to generate thermoacoustic computerized tomography (TCT) signal couple directly into the pulser-receiver and oscilloscope, swamping true TCT signal. We use a standard RF enclosure housing both RF amplifier and object being imaged. This is similar to RF shielding of magnetic resonance imaging (MRI) suites and protects electronics outside from stray RF. Unlike MRI, TCT receivers are ultrasound transducers, which must also be shielded from RF. A transducer housing that simultaneously shields RF and permits acoustic transmission was developed specifically for TCT. We compare TCT signals measured with and without RF shielding.
Mitchell, M.; Becker, G.; Dey, P.; Generotzky, J.; Patch, S. K.
Geochemical Structure of the Hawaiian Plume: Constrains from the Shield to Postshield Transition
NASA Astrophysics Data System (ADS)
The spatial arrangement of modern Hawaiian volcanoes forms two volcanic trends, the Kea and Loa trends. Shield stage lavas from these two volcanic trends have notable geochemical differences (e.g., Loa shield lavas have higher La/Nb, ^{208}Pb*/206Pb*, 87Sr/86Sr, and lower ^{143}Nd/^{144}Nd, ^{176}Hf/^{177}Hf than Kea shield lavas). During the shield to postshield stage transition, a Hawaiian volcano moves toward the edge of the plume; hence, an important question is -- Do Kea and Loa postshield stage lavas also exhibit different geochemical characteristics? Answer to this question provides constraints on the structure of the Hawaiian plume. The shield to postshield transition has been studied at several Kea volcanoes, but at only one Loa volcano, Hualalai. Xu et al. (2005) noted that the Pb isotopic difference between Loa and Kea shield lavas (Abouchami et al., 2005) carries over to postshield stage lavas. That is, compared with Loa trend lavas, Kea postshield lavas have relatively lower ^{208}Pb/204Pb at a given 206Pb/204Pb. At Kea volcanoes, postshield stage lavas have relatively lower 87Sr/86Sr and higher ^{143}Nd/^{144}Nd than shield stage lavas. Chen and Frey (1983) suggested that during the shield to postshield transition, a MORB-related depleted component was more involved as a Kea volcano moved off the plume. However, recent study shows that the depleted component in Kea postshield stage lavas is not MORB- related; rather, it is intrinsic within the Hawaiian plume (Xu et al., 2005). In contrast, at Hualalai, shield and postshield lavas have similar 87Sr/86Sr and ^{143}Nd/^{144}Nd (Cousens et al., 2003). Our new Sr-Nd isotopic data on Kahoolawe postshield lavas, another Loa volcano, show that 87Sr/86Sr and ^{143}Nd/^{144}Nd in Kahoolawe postshield lavas (0.703737-0.704545 and 0.512923-0.512799, respectively) overlap those in Kahoolawe shield lavas (0.703785-0.704399 and 0.512975-0.512731, respectively). Therefore, Loa and Kea volcanoes have different types of shield to postshield transition. The geochemical differences manifested in Kea and Loa shield lavas have been used to infer the geochemical structure of the Hawaiian plume. Lassiter et al. (1996) proposed a concentrically zoned plume model, and a modified version of this model is presented in DePaolo et al. (2001) and Bryce et al. (2005). Based on the Kea- Loa Pb isotopic difference, Abouchami et al. (2005) proposed a bilaterally asymmetric plume model. In contrast, based on melt inclusion study, Ren et al. (2005) proposed a pure thermally zoned plume model in which Kea and Loa components are randomly distributed within the Hawaiian plume, and the observed Kea- Loa geochemical difference reflects the thermal structure of the Hawaiian plume. Huang et al. (2005) speculated that the Hawaiian plume contains three source components with different solidus temperatures. The Kea and Loa geochemical difference reflects a temperature difference between Kea and Loa volcanoes that reflects their distance from the hot plume center. The observed different types of shield to postshield transition at Kea and Loa volcanoes cannot be explained by a simple concentrically zoned plume model, a bilaterally asymmetric model or a pure thermally zoned plume model. Rather, it may be explained by the modified concentrically zoned plume model in which the plume material is dragged downstream by the lithosphere (DePaolo et al., 2001; Bryce et al., 2005).
Huang, S.; Bizimis, M.; Fodor, R. V.; Bauer, G. R.
Decontaminating lead bricks and shielding
Lead used for shielding is often surface contaminated with radioisotopes and is therefore a RCRA D008 mixed waste. The technology-based standard for treatment is macroencapsulation. However, decontaminating and recycling the clean lead is a more attractive solution. Los Alamos National Laboratory decontaminates material and equipment contaminated with radioisotopes. Decontaminating lead poses special problems because of the RCRA hazard classification and the size of the inventory, now about 50 tons and likely to grow substantially of planned decommissioning operations. Thus lead, in the form of bricks and other shield shapes, is surface contaminated with fission products. One of the best methods for contaminated lead is removing the superficial layer of contamination with an abrasive medium under pressure. For lead, a mixture of alumina with water and air at about 40 psig rapidly and effectively decontaminates the lead. The abrasive medium is sprayed onto the lead in a scaled-off area. The slurry of abrasive and particles of lead falls through a floor and is collected in a sump. A pump sends the slurry mixture back to the spray gun, creating a continuous process. The process generates small volumes of lead slurry that can be solidified and, because it passes the TCLP, is not a mixed waste. The decontaminated lead can be released for recycling.
Lussiez, G.
Decontaminating lead bricks and shielding
Lead used for shielding is often surface contaminated with radioisotopes and is therefore a RCRA D008 mixed waste. The technology-based standard for treatment is macroencapsulation. However, decontaminating and recycling the clean lead is a more attractive solution. Los Alamos National Laboratory decontaminates material and equipment contaminated with radioisotopes. Decontaminating lead poses special problems because of the RCRA hazard classification and the size of the inventory, now about 50 tons and likely to grow substantially because of planned decommissioning operations. This lead, in the form of bricks and other shield shapes, is surface contaminated with fission products. One of the best methods for decontaminating lead is removing the thin superficial layer of contamination with an abrasive medium trader pressure. For lead, a mixture of alumina with water and air at about 40 psig rapidly and effectively decontaminates the lead. The abrasive medium is sprayed onto the lead in a sealed-off area. The slurry of abrasive and particles of lead falls through a floor grating and is collected in a sump. A pump sends the slurry mixture back to the spray gun, creating a continuous process. The process generates small volumes of contaminated lead slurry that can be solidified and, because it passes the TCLP, is not a mixed waste. The decontaminated lead can be released for recycling.
Lussiez, G.W.
Decontaminating lead bricks and shielding
Lead used for shielding is often surface contaminated with radioisotopes and is therefore a RCRA D008 mixed waste. The technology-based standard for treatment is macroencapsulation. However, decontaminating and recycling the clean lead is a more attractive solution. Los Alamos National Laboratory decontaminates material and equipment contaminated with radioisotopes. Decontaminating lead poses special problems because of the RCRA hazard classification and the size of the inventory, now about 50 tons and likely to grow substantially because of planned decommissioning operations. This lead, in the form of bricks and other shield shapes, is surface contaminated with fission products. One of the best methods for decontaminating lead is removing the thin superficial layer of contamination with an abrasive medium trader pressure. For lead, a mixture of alumina with water and air at about 40 psig rapidly and effectively decontaminates the lead. The abrasive medium is sprayed onto the lead in a sealed-off area. The slurry of abrasive and particles of lead falls through a floor grating and is collected in a sump. A pump sends the slurry mixture back to the spray gun, creating a continuous process. The process generates small volumes of contaminated lead slurry that can be solidified and, because it passes the TCLP, is not a mixed waste. The decontaminated lead can be released for recycling.
Lussiez, G.W.
Simulation analysis for the materials shielding effectiveness of EMP
The theory of shielding is introduced, and the simulation model is built. The software based on the CST is applied to simulate and analyze the pulse waveform. The shielding effectiveness of different pulse width is computed. Comparing the pulse shielding effectiveness with continuous wave shielding effectiveness, there is consistent result approximately. And the shielding effectiveness based on the frequency function
Long Zhang; Xiaofeng Hu; Xinfu Lu; Genchun Zhu; Yongqiang Zhang
Optimal application of multilayer shielding for maximal EM field attenuation
A two-surface cable shield periodic bondings and with either discrete or distributed excitation is analyzed. It is found that the bondings improve the overall shielding effectiveness of the cable shield at certain frequencies, but degrade the shielding at others. Certain criteria are established for better shielding. In the case of distributed excitation, the overall effective transfer functions of a two-surface
F. C. Yang; K. S. H. Lee
Geometrical aspects of magnetic shielding at extremely low frequencies
The magnetic shielding effectiveness for closed and open shield structures is studied at extremely low frequencies. Analytical solutions are used for simple geometries, while more complex structures are evaluated using a finite-element method. Both highly conductive and ferromagnetic materials are studied, and their different shielding behavior is shown. Ferromagnetic shields give good results for small and closed shields and they
Lennart Hasselgren; Jorma Luomi
Nuclear data relevant to shield design of FMIT facility
Nuclear data requirements are reviewed for the design of the Fusion Materials Irradiation Test (FMIT) facility. This accelerator-based facility, now in the early stages of construction at Hanford, will provide high fluences in a fusion-like radiation environment for the testing of materials. The nuclear data base required encompasses the entire range of neutron energies from thermal to 50 MeV. In this review, we consider neutron source terms, cross sections for thermal and bulk shield design, and neutron activation for the facility.
Carter, L.L.; Morford, R.J.; Wilcox, A.D.
Effect of shielding surfaces on the irradiance received by tilted collectors
This paper reports on a model which is developed to predict the total solar irradiance received by a tilted collector in the presence of a large shielding tilted surface. The model is suggested to replace the commonly accepted isotropic model which does not account for a shielding surface. The present model is found to depend mainly on the configuration factors between the collector and the sky and the ground in the presence of a shielding surface. Expressions for these configuration factors are derived for a general geometry of the collector and a large shielding surface. These expressions are found to depend on the tilt angles of the collector and the surface, the orientation angle and the location of the collector relative to the surface, and the height and width of the shielding surface. The expressions are verified numerically and also, by comparing them with the results obtained from the literature for special geometries. The expressions are simplified to facilitate their use for the case of a vertical collector and a vertical shielding surface. This special case is needed to accurately estimate the solar irradiance received by glass windows of buildings.
Al-Beirutty, M.H.; Elsayed, M.M. (Mechanical Engineering Dept., King Abdulaziz Univ., Jeddah 21413 (Saudi Arabia))
Underground barrier construction apparatus with soil-retaining shield
An apparatus for building a horizontal underground barrier by cutting through soil and depositing a slurry, preferably one which cures into a hardened material. The apparatus includes a digging means for cutting and removing soil to create a void under the surface of the ground, a shield means for maintaining the void, and injection means for inserting barrier-forming material into the void. In one embodiment, the digging means is a continuous cutting chain. Mounted on the continuous cutting chain are cutter teeth for cutting through soil and discharge paddles for removing the loosened soil. This invention includes a barrier placement machine, a method for building an underground horizontal containment barrier using the barrier placement machine, and the underground containment system. Preferably the underground containment barrier goes underneath and around the site to be contained in a bathtub-type containment.
Gardner, Bradley M. (Idaho Falls, ID) [Idaho Falls, ID; Smith, Ann Marie (Pocatello, ID) [Pocatello, ID; Hanson, Richard W. (Spokane, WA) [Spokane, WA; Hodges, Richard T. (Deer Park, WA) [Deer Park, WA
Underground barrier construction apparatus with soil-retaining shield
An apparatus is described for building a horizontal underground barrier by cutting through soil and depositing a slurry, preferably one which cures into a hardened material. The apparatus includes a digging means for cutting and removing soil to create a void under the surface of the ground, a shield means for maintaining the void, and injection means for inserting barrier-forming material into the void. In one embodiment, the digging means is a continuous cutting chain. Mounted on the continuous cutting chain are cutter teeth for cutting through soil and discharge paddles for removing the loosened soil. This invention includes a barrier placement machine, a method for building an underground horizontal containment barrier using the barrier placement machine, and the underground containment system. Preferably the underground containment barrier goes underneath and around the site to be contained in a bathtub-type containment. 17 figs.
Gardner, B.M.; Smith, A.M.; Hanson, R.W.; Hodges, R.T.
Mars Science Laboratory's Descent Stage
NASA Technical Reports Server (NTRS)This portion of NASA's Mars Science Laboratory, called the descent stage, does its main work during the final few minutes before touchdown on Mars. The descent stage will provide rocket-powered deceleration for a phase of the arrival at Mars after the phases using the heat shield and parachute. When it nears the surface, the descent stage will lower the rover on a bridle the rest of the way to the ground. The Mars Science Laboratory spacecraft is being assembled and tested for launch in 2011. This image was taken at NASA's Jet Propulsion Laboratory, Pasadena, Calif., which manages the Mars Science Laboratory Mission for NASA's Science Mission Directorate, Washington. JPL is a division of the California Institute of Technology.
Potential of building-scale alternative energy to alleviate risk from the future price of energy
The energy used for building operations, the associated greenhouse gas emissions, and the uncertainties in future price of natural gas and electricity can be a cause of concern for building owners and policy makers. In this work we explore the potential of building-scale alternative energy technologies to reduce demand and emissions while also shielding building owners from the risks associated
David Bristow; Christopher A. Kennedy
Throughput of shielded twisted-pair cables using wire-shield modes in the presence of radio ingress
This paper investigates the achievable throughput of shielded twisted-pair (STP) copper cables exploiting alternative propagation modes. Treating the shield as joint common, we form wire-shield paths. The shield is expected to substantially reduce the amount of radio ingress entering the cable. Thus, we consider the impact of the shield effectiveness on the throughput limits. Using model and measurements presented in
M. Jakovljevic; T. Magesacher; P. O. Borjesson; M. Sanchez; S. Zazo
Current status of methods for shielding analysis
Current methods used in shielding analysis and recent improvements in those methods are discussed. The status of methods development is discussed based on needs cited at the 1977 International Conference on Reactor Shielding. Additional areas where methods development is needed are discussed.
Engle, W.W.
Shielded Aluminum Flat-Conductor Cable
NASA Technical Reports Server (NTRS)
Thin wiring harness stores compactly. Flat aluminum conductors glued between layers of polyimide. Aluminum shield surrounds insulated conductors. Outer layer polyimide. Aluminum shield reduces flexibility of cable and cable withstand only limited number of repetitions of sharp bending at same spot.
Farina, S.
Thermal neutron shield and method of manufacture
A thermal neutron shield comprising concrete with a high percentage of the element Boron. The concrete is least 54% Boron by weight which maximizes the effectiveness of the shielding against thermal neutrons. The accompanying method discloses the manufacture of Boron loaded concrete which includes enriching the concrete mixture with varying grit sizes of Boron Carbide.
Brindza, Paul Daniel; Metzger, Bert Clayton
Undulator Beam Pipe Magnetic Shielding Effect Tests.
National Technical Information Service (NTIS)
The proposed stainless steel beampipe for the LCLS undulator has a measurable shielding effect on the magnetic field of the LCLS undulators. This note describes the tests used to determine the magnitude of the shielding effect, as well as deviations in th...
Z. Wolf
SHIELD: a comprehensive earth-protection architecture
The greatest natural threat to the long-term survivability of mankind is an asteroid or comet impact with the Earth. SHIELD is an architectural concept for a comprehensive Earth defense system designed to discover, catalog, calculate orbits of near-Earth objects, and to deflect potential impactors. SHIELD consists of Sentries, Soldiers, and an Earth Control Center. Sentries are spacecraft designed to search
R. E. Gold
Thermosetting polymer composites for EMI shielding applications
Efforts have been made towards developing lightweight EMI shielding thermosetting composites materials using room temperature curing epoxy novalac cyclo aliphatic amine hardener system. Average Shielding efficiency (SE) values (100 KHz to 1 GHz) of above 50 dB have been obtained for Carbon Fibre Reinforced Polymeric (CFRP) composite laminates, with variants of glass fabric and aluminium mesh included along with. Sandwich
S. Sankaran; S. Dasgupta; K. Ravi Sekhar; M. N. Jagdish Kumar
Material shields against neutral atomic particle beams
A material shield designed to protect a spacecraft against an atomic particle beam will, of necessity, be quite massive; consequently, even modest fractional-weight savings would be significant. With this goal in mind, the particle stopping power and range in various materials were investigated. The lightest shield materials are compounds composed of hydrogen and other light elements.
S. W. Kash
Chiroshield - A Salisbury/Dallenbach shield alternative
NASA Astrophysics Data System (ADS)
The enhancement of impedance matching and the increased absorption afforded by the use of chiral materials are here combined with specified coated surfaces which act as screens or shields for use in radar cross-section management and control. These chiral shields offer attractive advantages with respect to broadband frequency response and reduced reflection when compared to their conventional counterparts.
Jaggard, D. L.; Engheta, N.; Liu, J.
Whipple shield performance in the shatter regime
A series of hypervelocity impact tests have been performed on aluminum alloy Whipple shields to investigate failure mechanisms and performance limits in the shatter regime. Test results demonstrated a more rapid increase in performance than predicted by the latest iteration of the JSC Whipple shield ballistic limit equation (BLE) following the onset of projectile fragmentation. This increase in performance was
S. Ryan; M. Bjorkman; E. L. Christiansen
Shielding Strategies for Human Space Exploration
NASA Astrophysics Data System (ADS)
A group of twenty-nine scientists and engineers convened a 'Workshop on Shielding Strategies for Human Space Exploration' at the Lyndon B. Johnson Space Center in Houston, Texas. The provision of shielding for a Mars mission or a Lunar base from the hazards of space radiations is a critical technology since astronaut radiation safety depends on it and shielding safety factors to control risk uncertainty appear to be great. The purpose of the workshop was to define requirements for the development and evaluation of high performance shield materials and designs and to develop ideas regarding approaches to radiation shielding. The workshop was organized to review the recent experience on shielding strategies gained in studies of the 'Space Exploration Initiative (SEI),' to review the current knowledge base for making shield assessment, to examine a basis for new shielding strategies, and to recommend a strategy for developing the required technologies for a return to the moon or for Mars exploration. The uniqueness of the current workshop arises from the expected long duration of the missions without the protective cover of the geomagnetic field in which the usually small and even neglected effects of the galactic cosmic rays (GCR) can no longer be ignored. It is the peculiarity of these radiations for which the inter-action physics and biological action are yet to be fully understood.
Wilson, J. W.; Miller, J.; Konradi, A.; Cucinotta, F. A.
SINEX: SCALE shielding analysis GUI for X-Windows
SINEX (SCALE Interface Environment for X-windows) is an X-Windows graphical user interface (GUI), that is being developed for performing SCALE radiation shielding analyses. SINEX enables the user to generate input for the SAS4/MORSE and QADS/QAD-CGGP shielding analysis sequences in SCALE. The code features will facilitate the use of both analytical sequences with a minimum of additional user input. Included in SINEX is the capability to check the geometry model by generating two-dimensional (2-D) color plots of the geometry model using a new version of the SCALE module, PICTURE. The most sophisticated feature, however, is the 2-D visualization display that provides a graphical representation on screen as the user builds a geometry model. This capability to interactively build a model will significantly increase user productivity and reduce user errors. SINEX will perform extensive error checking and will allow users to execute SCALE directly from the GUI. The interface will also provide direct on-line access to the SCALE manual.
Browman, S.M.; Barnett, D.L.
Recycled oceanic crust in the Hawaiian Plume: evidence from temporal geochemical variations within the Koolau Shield
The subaerial surface of Koolau volcano is composed of lavas that define the distinctive endmember composition for Hawaiian shield lavas, known as the Koolau component, now designated as the Makapuu-stage. The geochemical characteristics of lavas recovered by the Koolau Scientific Drilling Project (KSDP) show that this distinctive composition forms a 80�ka; therefore it was not caused by an abrupt event,
Shichun Huang; Frederick A. Frey
Spacesuit Radiation Shield Design Methods
NASA Technical Reports Server (NTRS)
Meeting radiation protection requirements during EVA is predominantly an operational issue with some potential considerations for temporary shelter. The issue of spacesuit shielding is mainly guided by the potential of accidental exposure when operational and temporary shelter considerations fail to maintain exposures within operational limits. In this case, very high exposure levels are possible which could result in observable health effects and even be life threatening. Under these assumptions, potential spacesuit radiation exposures have been studied using known historical solar particle events to gain insight on the usefulness of modification of spacesuit design in which the control of skin exposure is a critical design issue and reduction of blood forming organ exposure is desirable. Transition to a new spacesuit design including soft upper-torso and reconfigured life support hardware gives an opportunity to optimize the next generation spacesuit for reduced potential health effects during an accidental exposure.
Wilson, John W.; Anderson, Brooke M.; Cucinotta, Francis A.; Ware, J.; Zeitlin, Cary J.
Background simulations and shielding calculations
Key improvements in the sensitivity of the underground particle astrophysics experiments can only be achieved if the radiation causing background events in detectors is well understood and proper measures are taken to suppress it. The background radiation arising from radioactivity and cosmic-ray muons is discussed here together with the methods of its suppression. Different shielding designs are considered to attenuate gamma-rays and neutrons coming from radioactivity in rock and lab walls. Purity of materials used in detector construction is analysed and the background event rates due to the presence of radioactive isotopes in detector components are discussed. Event rates in detectors caused by muon-induced neutrons with and without active veto systems are presented leading to the requirements for the depth of an underground laboratory and the efficiency of the veto system.
Kudryavtsev, Vitaly A. [Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH (United Kingdom)
Radiation Shielding Systems Using Nanotechnology
NASA Technical Reports Server (NTRS)
A system for shielding personnel and/or equipment from radiation particles. In one embodiment, a first substrate is connected to a first array or perpendicularly oriented metal-like fingers, and a second, electrically conducting substrate has an array of carbon nanostructure (CNS) fingers, coated with an electro-active polymer extending toward, but spaced apart from, the first substrate fingers. An electric current and electric charge discharge and dissipation system, connected to the second substrate, receives a current and/or voltage pulse initially generated when the first substrate receives incident radiation. In another embodiment, an array of CNSs is immersed in a first layer of hydrogen-rich polymers and in a second layer of metal-like material. In another embodiment, a one- or two-dimensional assembly of fibers containing CNSs embedded in a metal-like matrix serves as a radiation-protective fabric or body covering.
Chen, Bin (Inventor); McKay, Christoper P. (Inventor)
Electromagnetic interference shielding effectiveness of monolayer graphene.
We report the first experimental results on the electromagnetic interference (EMI) shielding effectiveness (SE) of monolayer graphene. The monolayer CVD graphene has an average SE value of 2.27 dB, corresponding to ~40% shielding of incident waves. CVD graphene shows more than seven times (in terms of dB) greater SE than gold film. The dominant mechanism is absorption rather than reflection, and the portion of absorption decreases with an increase in the number of graphene layers. Our modeling work shows that plane-wave theory for metal shielding is also applicable to graphene. The model predicts that ideal monolayer graphene can shield as much as 97.8% of EMI. This suggests the feasibility of manufacturing an ultrathin, transparent, and flexible EMI shield by single or few-layer graphene. PMID:23085718
Hong, Seul Ki; Kim, Ki Yeong; Kim, Taek Yong; Kim, Jong Hoon; Park, Seong Wook; Kim, Joung Ho; Cho, Byung Jin
High-Speed Penetration Modeling and Shape Optimization of the Projectile Penetrating into Concrete Shields
We generalize the existing engineering approaches to modeling of high-speed penetration of projectiles into semi-infinite concrete shields and suggest a modified semi-empirical two-stage model that is applicable for bodies of revolution with a flat bluntness. At the first stage of penetration (cratering), the resistance force is described as a linear function of the instantaneous distance between the nose of the
G. Ben-Dor; A. Dubinsky; T. Elperin
An intrinsically safe facility for forefront research and training on nuclear technologies � ADS shielding
NASA Astrophysics Data System (ADS)
A detailed study of a very simple Accelerator-Driven System (ADS) shielding concept is carried out by means of the MCNPX Monte Carlo code. The design of a multilayer shielding scheme, together with an underground reactor host room sketch, is shown to be very effective for the exposure levels to ionizing radiations, in the upside experimental building and in the ground all around the reactor host room, being fully negligible. Transient heat is also estimated, founding that no residual radiation leaks out through ADS structures in the host room after shutdown.
Frasciello, O.; Ciotti, M.
Once the third stage finishes its work, Kepler will have sufficient energy to leave the gravitational pull of Earth and go into orbit around the Sun, trailing behind Earth and slowly drifting away ...
Performance of Whipple Shields at Impact Velocities above 9 km/s
NASA Technical Reports Server (NTRS)
Whipple shields were first proposed as a means of protecting spacecraft from the impact of micrometeoroids in 1947 [1] and are currently in use as micrometeoroid and orbital debris shields on modern spacecraft. In the intervening years, the function of the thin bumper used to shatter or melt threatening particles has been augmented and enhanced by the use of various types and configurations of intermediate layers of various materials. All shield designs serve to minimize the threat of a spall failure or perforation of the main wall of the spacecraft as a result of the impact of the fragments. With increasing use of Whipple shields, various ballistic limit equations (BLEs) for guiding the design and estimating the performance of shield systems have been developed. Perhaps the best known and most used are the "new" modified Cour-Palais (Christiansen) equations [2]. These equations address the three phases of impact: (1) ballistic (<3 km/s), where the projectile is moving too slowly to fragment and essentially penetrates as an intact projectile; (2) shatter (3 to 7 km/s), where the projectile fragments at impact and forms an expanding cloud of debris fragments; and (3) melt/vaporization (>7 km/s), where the projectile melts or vaporizes at impact. The performance of Whipple shields and the adequacy of the BLEs have been examined for the first two phases using the results of impact tests obtained from two-stage, light-gas gun test firings. Shield performance and the adequacy of the BLEs has not been evaluated in the melt/vaporization phase until now because of the limitations of launchers used to accelerate projectiles with controlled properties to velocities above 7.5 km/s. A three-stage, light-gas gun, developed at the University of Dayton Research Institute (UDRI) [3], is capable of launching small, aluminum spheres to velocities above 9 km/s. This launcher was used to evaluate the ballistic performance of two Whipple shield systems, various thermal protection system materials, and other spacecraft-related materials to the impact of 1.6-mm- to 2.6-mm-diameter, 2017-T4 aluminum spheres at impact velocities ranging from 8.91 km/s to 9.28 km/s. Test results, details of the shield systems, and nominal ballistic limits for the two Whipple shields are shown in Figures 1 and 2.
Christiansen, Eric L.; Davis, Bruce A.; Piekutowski, Andrew J.; Poormon, Kevin L.
Integrated Solar Concentrator and Shielded Radiator
NASA Technical Reports Server (NTRS)
A shielded radiator is integrated within a solar concentrator for applications that require protection from high ambient temperatures with little convective heat transfer. This innovation uses a reflective surface to deflect ambient thermal radiation, shielding the radiator. The interior of the shield is also reflective to provide a view factor to deep space. A key feature of the shield is the parabolic shape that focuses incoming solar radiation to a line above the radiator along the length of the trough. This keeps the solar energy from adding to the radiator load. By placing solar cells along this focal line, the concentration of solar energy reduces the number and mass of required cells. By shielding the radiator, the effective reject temperature is much lower, allowing lower radiator temperatures. This is particularly important for lower-temperature processes, like habitat heat rejection and fuel cell operations where a high radiator temperature is not feasible. Adding the solar cells in the focal line uses the concentrating effect of the shield to advantage to accomplish two processes with a single device. This shield can be a deployable, lightweight Mylar structure for compact transport.
Clark, David Larry
International Space Station Radiation Shielding Model Development
NASA Technical Reports Server (NTRS)
The projected radiation levels within the International Space Station (ISS) have been criticized by the Aerospace Safety Advisory Panel in their report to the NASA Administrator. Methods for optimal reconfiguration and augmentation of the ISS shielding are now being developed. The initial steps are to develop reconfigurable and realistic radiation shield models of the ISS modules, develop computational procedures for the highly anisotropic radiation environment, and implement parametric and organizational optimization procedures. The targets of the redesign process are the crew quarters where the astronauts sleep and determining the effects of ISS shadow shielding of an astronaut in a spacesuit. The ISS model as developed will be reconfigurable to follow the ISS. Swapping internal equipment rack assemblies via location mapping tables will be one option for shield optimization. Lightweight shield augmentation materials will be optimally fit to crew quarter areas using parametric optimization procedures to minimize the augmentation shield mass. The optimization process is being integrated into the Intelligence Synthesis Environment s (ISE s) immersive simulation facility at the Langley Research Center and will rely on High Performance Computing and Communication (HPCC) for rapid evaluation of shield parameter gradients.
Qualls, G. D.; Wilson, J. W.; Sandridge, C.; Cucinotta, F. A.; Nealy, J. E.; Heinbockel, J. H.; Hugger, C. P.; Verhage, J.; Anderson, B. M.; Atwell, W.
Graphitic heat shields for solar probe missions
NASA Technical Reports Server (NTRS)
The feasibility of using a graphitic heat-shield system on a solar probe going to within 4 solar radii of the center of the sun is investigated. An analysis of graphite vaporization, with commonly used vaporization coefficients, indicates that the maximum mass-loss rate from a conical shield as large as 4 m in diameter can be kept low enough to avoid interference with measurements of the solar environment. In addition to the mass-loss problem, the problem of protecting the payload from the high-temperature (up to 2300 K) primary shield must be solved. An analysis of radiation exchange between concentric disks provides a technique for designing the intermediate shielding. The technique is applied to the design of a system for the Starprobe spacecraft, and it is found that a system with 10 shields and a payload surface temperature of 600 K will have a payload diameter of 2.45 m. Since this is 61% of the 4-m diameter of the primary shield, it is concluded that a graphitic heat-shield system is feasible for the Starprobe mission.
Lundell, J. H.
Shielding options for the ITER conceptual design
Several shield options were analyzed for the ITER conceptual design to minimize the nuclear responses in the toroidal field (TF) coils. The total nuclear heating in the physics phase and the insulator dose in the technology phase are the most critical parameters in the design process. The first shield option has type 316 stainless steel and water shielding material. Steel and water also serve as structural material and coolant, respectively. The second option is similar to the first except that borated water is used instead of ordinary water. The other two options include a small layer of lead or boron carbide (B{sub 4}C) at the back of the shield. The last three shield options were considered to reduce the nuclear heating in the toroidal field coils relative to the steel/water shield. An optimization process was performed taking into consideration the thermal-hydraulics and the engineering requirements to define the shield configuration. A careful integration was performed to calculate the total nuclear heating in the toroidal field coils which account for the neutron wall loading distribution, the change in the shield thickness in the poloidal direction, and the space between the toroidal field coils in the divertor zone. The results show that the steel/water/Pb and the steel/borated-water shield options are very close in terms of the total nuclear heating in the toroidal field coils and the dose in the insulator material. The other two options, steel/water and steel/water/B{sub 4}C deposit more nuclear heating in the toroidal field coils. 5 refs., 3 figs., 5 tabs.
Gohar, Y.; Attaya, H. (Argonne National Lab., IL (USA))
MFTF-. cap alpha. + T shield design
MFTF-..cap alpha..+T is a DT upgrade option of the Tandem Mirror Fusion Test Facility (MFTF-B) to study better plasma performance, and test tritium breeding blankets in an actual fusion reactor environment. The central cell insert, designated DT axicell, has a 2-MW/m/sup 2/ neutron wall loading at the first wall for blanket testing. This upgrade is completely shielded to protect the reactor components, the workers, and the general public from the radiation environment during operation and after shutdown. The shield design for this upgrade is the subject of this paper including the design criteria and the tradeoff studies to reduce the shield cost.
Gohar, Y.
Optimization design of electromagnetic shielding composites
NASA Astrophysics Data System (ADS)
The effective electromagnetic parameters physical model of composites and prediction formulas of composites' shielding effectiveness and reflectivity were derived based on micromechanics, variational principle and electromagnetic wave transmission theory. The multi-objective optimization design of multilayer composites was carried out using genetic algorithm. The optimized results indicate that material parameter proportioning of biggest absorption ability can be acquired under the condition of the minimum shielding effectiveness can be satisfied in certain frequency band. The validity of optimization design model was verified and the scheme has certain theoretical value and directive significance to the design of high efficiency shielding composites.
Qu, Zhaoming; Wang, Qingguo; Qin, Siliang; Hu, Xiaofeng
Low background shielding of HPGe detector.
National Radiation Protection Institute in Prague is equipped with 14 HPGe detectors with relative efficiency up to 150%. Steel shielding with one of these detectors (relative efficiency 100%) was chosen to be rebuilt to decrease minimum detectable activity (MDA). Additional lead and copper shielding was built up inside the original steel shielding to reduce the volume of the inner space and filled with nitrogen by means of evaporating liquid nitrogen. MDA values decreased for Compton background up to 0.67 of original value. PMID:19243960
Trnkov�, L; Rul�k, P
Hot cell shield plug extraction apparatus
An apparatus is provided for moving shielding plugs into and out of holes in concrete shielding walls in hot cells for handling radioactive materials without the use of external moving equipment. The apparatus provides a means whereby a shield plug is extracted from its hole and then swung approximately 90 degrees out of the way so that the hole may be accessed. The apparatus uses hinges to slide the plug in and out and to rotate it out of the way, the hinge apparatus also supporting the weight of the plug in all positions, with the load of the plug being transferred to a vertical wall by means of a bolting arrangement.
Knapp, Philip A. (Moore, ID); Manhart, Larry K. (Pingree, ID)
System requirements of Starprobe thermal shield
NASA Technical Reports Server (NTRS)
The mission of the Starprobe Spacecraft is to do in situ exploration of the solar corona to four solar radii. A thermal shield is required to protect the spacecraft equipment from a 3000 sun incident solar energy level caused by this close approach to the sun. The thermal shield requirements discussed include configuration, material requirements, temperature level, penetrations, outgassing and mass loss, and contamination as referenced to spacecraft mission parameters. Further, the size of the spacecraft will be limited by the space transport system orbiter payload bay dimensions, thus defining the upper limit of the relative sizes and locations of the heat shield and spacecraft equipment.
Miyake, R. N.; Noon, D.; Hultberg, J. A.
Flexible heat resistant neutron shielding resin
NASA Astrophysics Data System (ADS)
A flexible heat resistant neutron shielding material has been developed, which consists of polymer resin with 1 wt% boron. The neutron shielding performance of the developed resin, examined by the 252Cf neutron source, is almost the same as that of the polyethylene. The outgas of H 2, H 2O, CO and CO 2 from the resin have been measured at �250 �C environment. The resin will be applied around the port of the vacuum vessel as an additional shielding material and reduce the neutron streaming from a superconducting tokamak device such as JT-60SA.
Sukegawa, Atsuhiko M.; Anayama, Yoshimasa; Okuno, Koichi; Sakurai, Shinji; Kaminaga, Atsushi
Radiation shielding concrete made of Basalt aggregates.
In spite of the fact that Basalt is a widespread type of rock, there is very little available information on using it as aggregates for concrete radiation shielding. This paper investigates the possibility of using Basalt for the aforementioned purpose. The results have shown that Basalt could be used successfully for preparing radiation shielding concrete, but some attention should be paid to the choice of the suitable types of Basalt and for the neutron activation problem that could arise in the concrete shield. PMID:22933408
Alhajali, S; Yousef, S; Kanbour, M; Naoum, B
Effects of fluctuating magnetic fields on a superconducting bulk rotor shielded with superconducting rings
NASA Astrophysics Data System (ADS)
We study the effect of a fluctuating magnetic field, which is one of the technical problems for trapped magnetic fields in a bulk superconductor, to realize a practical bulk superconductor rotating machine. Previous research and other's research has shown that fluctuating magnetic fields reduce the strength of trapped magnetic fields in superconducting bulk modules [1, 2]. This deters development of applications of AC rotating machines because superconducting bulk modules are always exposed to a fluctuating magnetic field. Therefore, it is necessary to develop a method to control decrease of the trapped magnetic field. We propose a method to use the shielding ring of a superconducting wire to achieve this goal and the effects are confirmed experimentally [3]. We are now building test equipment for examining the performance of a shielding ring in a bulk rotating machine. This paper reports the test result for the shielding ring applied to the bulk superconducting rotor that is a part of the test equipment.
Yamagishi, K.; Ogawa, J.; Tsukamoto, O.
Preliminary design of a meteoroid/orbital debris shield system for a Mars mission spacecraft
NASA Technical Reports Server (NTRS)
A preliminary design of a spacecraft shield system to defeat meteoroids and orbital debris during a Mars mission is presented. The mission scenario is first defined in terms of stage times which include LEO, transit, low-Mars orbit, and Mars surface periods. The environment definitions for earth-orbital space debris, planetary meteoroids, and interplanetary meteoroids are next introduced. Shield system design approaches incorporate stochastic simulation, hydrocode analyses, hypervelocity impact testing, and optimization techniques. Structural design trades presented include spacecraft configuration, mission schedule, penetration risk, and total standoff distance between the bumper and wall.
Robinson, J. H.; Mog, R. A.
Ablative shielding for hypervelocity projectiles
NASA Technical Reports Server (NTRS)
A hypervelocity projectile shield which includes a hollow semi-flexible housing fabricated from a plastic like, or otherwise transparent membrane which is filled with a fluid (gas or liquid) is presented. The housing has a inlet valve, similar to that on a tire or basketball, to introduce an ablating fluid into the housing. The housing is attached by a Velcro mount or double-sided adhesive tape to the outside surface of a structure to be protected. The housings are arrayed in a side-by-side relationship for complete coverage of the surface to be protected. In use, when a hypervelocity projectile penetrates the outer wall of a housing it is broken up and then the projectile is ablated as it travels through the fluid, much like a meteorite 'burns up' as it enters the earth's atmosphere, and the housing is deflated. The deflated housing can be easily spotted for replacement, even from a distance. Replacement is then accomplished by simply pulling a deflated housing off the structure and installing a new housing.
Rucker, Michelle A. (inventor)
ERIC Educational Resources Information Center
Discusses the importance of developing students' building awareness by exploring logos, or buildings that symbolize a country, to learn about architecture and the cultures in different countries. Explores categories of buildings. Includes examples of logos from around the world. (CMK)
Meilach, Dona Z.
The Clinical Testing of Male Gonad Shields.
National Technical Information Service (NTIS)
Two types of male gonad shields, designed for use with support garments, were tested in a number of hospitals and clinics throughout the United States. The clinical evaluation consisted of: (1) Measuring dose reduction with thermoluminescent dosimeters; a...
W. W. Church, B. M. Burnett
Boron-10 loaded inorganic shielding material
NASA Technical Reports Server (NTRS)
Shielding material containing Boron 10 and gadoliunium for neutron absorption has been developed to reduce interference from low energy neutrons in measurement of fission neutron spectrum using Li-6 fast neutron spectrometer.
Baker, S. I.; Ryskiewicz, R. S.
Resonance self-shielding methodology in MPACT
The resonance self-shielding methods of the neutron transport code Michigan Parallel Characteristics based Transport (MPACT) are described in this paper. Two resonance-integral table based methods are utilized to resolve the resonance self-shielding effect. The subgroup method is a mature approach used in MPACT as the basic functionality for the resonance calculation. Another new iterative method, named the embedded self-shielding method is also implemented in MPACT. Comparisons of the two methods as well as their numerical verifications are presented. The results show that MPACT is capable of modeling the resonance self-shielding in a variety of PWR benchmarking cases, including difficult fuel lattice cases with poison, control rods or mixed gadolinia fuel rods. (authors)
Liu, Y.; Collins, B.; Kochunas, B.; Martin, W. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI, 48109 (United States)] [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI, 48109 (United States); Kim, K. S.; Williams, M. [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831-6172 (United States)] [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831-6172 (United States)
Shield Design for Lunar Surface Applications
NASA Astrophysics Data System (ADS)
A shielding concept for lunar surface applications of nuclear power is presented herein. The reactor, primary shield, reactor equipment and power generation module are placed in a cavity in the lunar surface. Support structure and heat rejection radiator panels are on the surface, outside the cavity. The reactor power of 1,320 kWt was sized to deliver 50 kWe from a thermoelectric power conversion subsystem. The dose rate on the surface is less than 0.6 mRem/hr at 100 meters from the reactor. Unoptimized shield mass is 1,020 kg which is much lighter than a comparable 4? shield weighing in at 17,000 kg.
Johnson, Gregory A.
Projectile Density Effects on Shield Performance
NASA Technical Reports Server (NTRS)
In the past, the orbital debris environment was modeled as consisting entirely of aluminum particles. As a consequence, most of the impact test database on spacecraft micro-meteoroid and orbital debris (MMOD) shields, and the resulting ballistic limit equations used to predict shielding performance, has been based on using aluminum projectiles. Recently, data has been collected from returned spacecraft materials and other sources that indicate higher and lower density components of orbital debris also exist. New orbital debris environment models such as ORDEM2008 provide predictions of the fraction of orbital debris in various density bins (high = 7.9 g/cu cm, medium = 2.8 g/cu cm, and low = 0.9-1.1 g/cu cm). This paper describes impact tests to assess the effects of projectile density on the performance capabilities of typical MMOD shields. Updates to shield ballistic limit equations are provided based on results of tests and analysis.
Christiansen, Eric L.; Lear, Dana; Lyons, Frankel; Davis, Alan
Shielding Requirements for Particle Bed Propulsion Systems.
National Technical Information Service (NTIS)
Nuclear Thermal Propulsion systems present unique challenges in reliability and safety. Due to the radiation incident upon all components of the propulsion system, shielding must be used to keep nuclear heating in the materials within limits; in addition,...
S. J. Gruneisen
Injection Molding Compound for Electromagnetic Shielding.
National Technical Information Service (NTIS)
A thermoplastic injection molding compound with excellent electromagnetic shielding effectiveness has been developed as a material for housings of electronic equipment. The compound contains stainless steel fiber as an electroconductive filler and maintai...
H. Takahama H. Tamaki T. Herai
Charge and Potential Distributions in Shielded Striplines.
National Technical Information Service (NTIS)
A new method is presented for calculating the charge and potential distribution in shielded microstrip lines with stratified dielectric fillings. The boundary value problem associated with this structure is formulated in a rigorous manner and the solution...
R. Mittra T. Itoh
Comparison of graphite, aluminum, and TransHab shielding material characteristics in a high-energy neutron field
NASA Technical Reports Server (NTRS)
Space radiation transport models clearly show that low atomic weight materials provide a better shielding protection for interplanetary human missions than high atomic weight materials. These model studies have concentrated on shielding properties against charged particles. A light-weight, inflatable habitat module called TransHab was built and shown to provide adequate protection against micrometeoroid impacts and good shielding properties against charged particle radiation in the International Space Station orbits. An experiment using a tissue equivalent proportional counter, to study the changes in dose and lineal energy spectra with graphite, aluminum, and a TransHab build-up as shielding, was carried out at the Los Alamos Nuclear Science Center neutron facility. It is a continuation of a previous study using regolith and doped polyethylene materials. This paper describes the results and their comparison with the previous study. Published by Elsevier Science Ltd.
Badhwar, G. D.; Huff, H.; Wilkins, R.; Thibeault, Sheila
X-ray transmissive debris shield
A composite window structure is described for transmitting x-ray radiation and for shielding radiation generated debris. In particular, separate layers of different x-ray transmissive materials are laminated together to form a high strength, x-ray transmissive debris shield which is particularly suited for use in high energy fluences. In one embodiment, the composite window comprises alternating layers of beryllium and a thermoset polymer.
Spielman, Rick B. (Albuquerque, NM) [Albuquerque, NM
CDF forward shielding for Run II
Detailed calculations of the accelerator related background in the CDF forward muon spectrometer have been performed with the MARS13 code and a newly developed C++ code for particle tracking in accelerator lattices. Calculated space distributions of background hits are in a good agreement with data taken in Run I. Several shielding configurations in the CDF hall and Tevatron tunnel have been studied. The optimal one provides a 30-fold shielding efficiency compatible with CDF Run II requirements.
Krivosheev, O.E.; Mokhov, N.V.
Nuclear reactor shield including magnesium oxide
An improvement in nuclear reactor shielding of a type used in reactor applications involving significant amounts of fast neutron flux, the reactor shielding including means providing structural support, neutron moderator material, neutron absorber material and other components as described below, wherein at least a portion of the neutron moderator material is magnesium in the form of magnesium oxide either alone or in combination with other moderator materials such as graphite and iron.
Rouse, Carl A. (Del Mar, CA); Simnad, Massoud T. (La Jolla, CA)
Earth pressure balance control for EPB shield
This paper mainly deals with the critical technology of earth pressure balance (EPB) control in shield tunneling. On the assumption\\u000a that the conditioned soil in the working chamber of the shield is plasticized, a theoretical principle for EPB control is\\u000a proposed. Dynamic equilibrium of intake volume and discharge volume generated by thrust and discharge is modeled theoretically\\u000a to simulate the
HuaYong Yang; Hu Shi; GuoFang Gong; GuoLiang Hu
Optimization of ferromagnetic shields for solenoid SMES
Ferromagnetic shields for solenoidal superconducting magnetic energy storages (SMES) are optimized with respect to the stray field or the mass of the shield. Two optimization strategies of zero order are compared: the deterministic downhill simplex method and the evolution strategy, a stochastic method. Due to the comparison a combination of both methods is tested. To guarantee short computation times the underlying nonlinear field analysis is based on an integral equation method.
Brammer, U.; Rasch, P. [Technische Univ. Muenchen (Germany). Lehrstuhl fuer Elektrische Maschinen] [Technische Univ. Muenchen (Germany). Lehrstuhl fuer Elektrische Maschinen
Undulator Beam Pipe Magnetic Shielding Effect Tests
The proposed stainless steel beampipe for the LCLS undulator has a measurable shielding effect on the magnetic field of the LCLS undulators. This note describes the tests used to determine the magnitude of the shielding effect, as well as deviations in the shielding effect caused by placing different phase shims in the undulator gap. The effect of the proposed Steel strongback which will be used to support the beam pipe, was also studied. A hall probe on a 3 axis movement system was set up to measure the main component of the magnetic field in the Prototype Undulator. To account for temperature variations of the magnetic field of the undulator for successive tests, a correction is applied which is described in this technical note. Using this method, we found the shielding effect, the amount which the field inside the gap was reduced due to the placement of the beampipe, to be {approx}10 Gauss. A series of tests was also performed to determine the effect of phase shims and X and Y correction shims on the shielding. The largest effect on shielding was found for the .3 mm phase shims. The effect of the .3 mm phase shims was to increase the shielding effect {approx}4 Gauss. The tolerance for the shielding effect of the phase shims is less than 1 gauss. The effect of the strongback was seen in its permanent magnetic field. It introduced a dipole field across the measured section of the undulator of {approx}3 gauss. This note documents the tests performed to determine these effects, as well as the results of those tests.
Fisher, Andrew; Wolf, Zachary; /SLAC; ,
ERIC Educational Resources Information Center
Uncertainty about identity and the future is occurring at a stage of life when people do question what they have achieved and what they still want to achieve. The notion of midlife crisis has been in existence for some time but recently its occurrence has coincided with opportunities to take early retirement or redundancy. This has meant that the�
Soulsby, Jim
National Technical Information Service (NTIS)
The fluid amplifier is utilized in a computing system. The pure fluid binary counting stage comprises a pair of pure fluid amplifiers coupled together through a delay and energy storage system such that one of the fluid through a delay and energy storage ...
R. E. Bowles
Reliability Methods for Shield Design Process
NASA Technical Reports Server (NTRS)
Providing protection against the hazards of space radiation is a major challenge to the exploration and development of space. The great cost of added radiation shielding is a potential limiting factor in deep space operations. In this enabling technology, we have developed methods for optimized shield design over multi-segmented missions involving multiple work and living areas in the transport and duty phase of space missions. The total shield mass over all pieces of equipment and habitats is optimized subject to career dose and dose rate constraints. An important component of this technology is the estimation of two most commonly identified uncertainties in radiation shield design, the shielding properties of materials used and the understanding of the biological response of the astronaut to the radiation leaking through the materials into the living space. The largest uncertainty, of course, is in the biological response to especially high charge and energy (HZE) ions of the galactic cosmic rays. These uncertainties are blended with the optimization design procedure to formulate reliability-based methods for shield design processes. The details of the methods will be discussed.
Tripathi, R. K.; Wilson, J. W.
Reliability Methods for Shield Design Process
NASA Astrophysics Data System (ADS)
Providing protection against the hazards of space radiation is a major challenge to the exploration and development of space. The great cost of added radiation shielding is a potential limiting factor in deep space operations. In this enabling technology, we have developed methods for optimized shield design over multi-segmented missions involving multiple work and living areas in the transport and duty phase of space missions. The total shield mass over all pieces of equipment and habitats is optimized subject to career dose and dose rate constraints. An important component of this technology is the estimation of two most commonly identified uncertainties in radiation shield design, the shielding properties of materials used and the understanding of the biological response of the astronaut to the radiation leaking through the materials into the living space. The largest uncertainty, of course, is in the biological response to especially high charge and energy (HZE) ions of the galactic cosmic rays. These uncertainties are blended with the optimization design procedure to formulate reliability-based methods for shield design processes. The details of the methods will be discussed.
Tripathi, R. K.; Wilson, J. W.
Hospital construction materials: poor shielding capacity with respect to signals transmitted by mobile telephones.
Electromagnetic interference (EMI) with electronic medical equipment by the handsets of mobile telephones is a well documented problem in hospitals. To gain information about how to build an EMI-free hospital and how to make rooms safe for mobile telephone handset use in the hospital building the authors measured the shielding capacities of a concrete wall, concrete blocks, a steel door, and steel-surfaced partition panels. The shielding capacities of these materials were 2-7 dB for the concrete wall, 6-8 dB for the concrete blocks, 19-27 dB for the steel door, and 20-37 dB for the steel-surfaced partition panels. These results indicate that care should be taken to shield electronic equipment from signals coming from neighboring rooms and from those under and above any patient room in which such equipment is in use. Electricity-conductive paint, electricity-conductive wallpaper, and electricity-conductive cloth are examples of inexpensive materials that can increase shielding capacity. PMID:9800005
Hanada, E; Watanabe, Y; Antoku, Y; Kenjo, Y; Nutahara, H; Nose, Y
Preliminary shielding estimates for the proposed National ISOL Radioactive Ion Beam (RIB) Facility at Oak Ridge
ORNL built a first-generation Radioactive Ion Beam (RIB) facility for astrophysics and nuclear physics research; it was named Holifield Radioactive Ion Beam Facility (HRIBF) and is based on the Isotope Separator On Line (ISOL) technique. Planning is underway for a second- generation facility, the National ISOL RIB facility at Oak Ridge; it will build on the existing HRIBF and may utilize many existing components and shielded areas. Preliminary upgrade plan for the new facility includes: adding a superconducting booster for the tandem accelerator; replacing the 1960-vintage, 60-MeV proton, 50-microamp ORIC (Oak Ridge Isochronous Cyclotron) with a modern 200-MeV proton, 200-microamp cyclotron; and building a high-power {sup 238}U fission target to accept the 200-MeV proton beam. This report summarizes the results of a preliminary 1-D shielding analysis of the proposed upgrade, to determine the shielding requirements for a 0.25 mrem/h dose rate at the external surface of the exclusion area. Steel shielding weights ranging from 60 to 100 metric tons, were considered manageable; these could be reduced by a factor of 2 to 3 if the orientation of the proposed target station was changed.
Johnson, J.O.; Gabriel, T.A.; Lillie, R.A.
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
VIEW OF BUILDING 440 LOOKING WEST, NORTHWEST. BUILDING 440, THE TRANSPORT MODIFICATION CENTER, CONSISTS OF FOUR HIGH-BAY CORRUGATED METAL STRUCTURES. BUILDING 440 WAS USED FOR PACKAGING AND STAGING SPECIAL NUCLEAR MATERIALS AND DEPLETED URANIUM FOR SHIPMENT AND TO MODIFY VEHICLES TO MEET SPECIFIC UNITED STATES DEPARTMENT OF ENERGY REQUIREMENTS. (2/8/84) - Rocky Flats Plant, Transport Modification Center, North of Cactus Avenue, approximately 400 feet east of Third Street, Golden, Jefferson County, CO
Space Shielding Materials for Prometheus Application
At the time of Prometheus program restructuring, shield material and design screening efforts had progressed to the point where a down-selection from approximately eighty-eight materials to a set of five ''primary'' materials was in process. The primary materials were beryllium (Be), boron carbide (B{sub 4}C), tungsten (W), lithium hydride (LiH), and water (H{sub 2}O). The primary materials were judged to be sufficient to design a Prometheus shield--excluding structural and insulating materials, that had not been studied in detail. The foremost preconceptual shield concepts included: (1) a Be/B{sub 4}C/W/LiH shield; (2) a Be/B{sub 4}C/W shield; (3) and a Be/B{sub 4}C/H{sub 2}O shield. Since the shield design and materials studies were still preliminary, alternative materials (e.g., {sup nal}B or {sup 10}B metal) were still being screened, but at a low level of effort. Two competing low mass neutron shielding materials are included in the primary materials due to significant materials uncertainties in both. For LiH, irradiation-induced swelling was the key issue, whereas for H{sub 2}O, containment corrosion without active chemistry control was key, Although detailed design studies are required to accurately estimate the mass of shields based on either hydrogenous material, both are expected to be similar in mass, and lower mass than virtually any alternative. Unlike Be, W, and B{sub 4}C, which are not expected to have restrictive temperature limits, shield temperature limits and design accommodations are likely to be needed for either LiH or H{sub 2}O. The NRPCT focused efforts on understanding swelting of LiH, and observed, from approximately fifty prior irradiation tests, that either casting ar thorough out-gassing should reduce swelling. A potential contributor to LiH swelling appears to be LiOH contamination due to exposure to humid air, that can be eliminated by careful processing. To better understand LiH irradiation performance and mitigate the risks in LiH development for a project with an aggressive schedule like JIMO, some background or advanced development effort for LiH should be considered for future space reactor projects.
R. Lewis
Magnetic shielding of interplanetary spacecraft against solar flare radiation
NASA Astrophysics Data System (ADS)
The ultimate objective of this work is to design, build, and fly a dual-purpose, piggyback payload whose function is to produce a large volume, low intensity magnetic field and to test the concept of using such a magnetic field (1) to protect spacecraft against solar flare protons, (2) to produce a thrust of sufficient magnitude to stabilize low satellite orbits against orbital decay from atmospheric drag, and (3) to test the magsail concept. These all appear to be capable of being tested using the same deployed high temperature superconducting coil. In certain orbits, high temperature superconducting wire, which has now been developed to the point where silver-sheathed high T sub c wires one mm in diameter are commercially available, can be used to produce the magnetic moments required for shielding without requiring any mechanical cooling system. The potential benefits of this concept apply directly to both earth-orbital and interplanetary missions. The usefulness of a protective shield for manned missions needs scarcely to be emphasized. Similarly, the usefulness of increasing orbit perigee without expenditure of propellant is obvious. This payload would be a first step in assessing the true potential of large volume magnetic fields in the US space program. The objective of this design research is to develop an innovative, prototype deployed high temperature superconducting coil (DHTSC) system.
Cocks, Franklin H.; Watkins, Seth
Shielding of manned space vehicles against protons and alpha particles
NASA Technical Reports Server (NTRS)
The available information on the shielding of manned space vehicles against protons and alpha particles is summarized. The emphasis is placed on shielding against Van Allen belt protons and against solar-flare protons and alpha particles, but information on shielding against galactic cosmic rays is also presented. The approximation methods for use by nonexperts in the space shielding field are those that are standard in the space shielding literature.
Alsmiller, R. G., Jr.; Santoro, R. T.; Barish, J.; Claiborne, H. C.
Simulating Building Fires for Movies
NASA Technical Reports Server (NTRS)
Fire scenes for cinematography staged at relatively low cost in method that combines several existing techniques. Nearly realistic scenes, suitable for firefighter training, produced with little specialized equipment. Sequences of scenes set up quickly and easily, without compromising safety because model not burned. Images of fire, steam, and smoke superimposed on image of building to simulate burning of building.
Rodriguez, Ricardo C.; Johnson, Randall P.
Investigation of photon shielding property changes in curing high density concrete.
High density concrete is usually used for radiation shielding around radiotherapy treatment rooms. Because the concrete is specified differently at the design, construction, and verification stages, the relationship between the intended performance and the actual performance of the shielding material might not be entirely clear. In this study, cylindrical samples of high density shielding concrete were taken as each section of a new radiotherapy bunker was poured. The shielding performance of each sample [measured by beam attenuation and tenth-value layers (TVL)] was evaluated for 15 MV and 6 MV x-ray beams and for the 1.25 MeV monoenergetic gamma beam from a Co source. Transmission curves to 3 TVL were mapped for a representative sample. The samples were also imaged and analyzed using Co Cone Beam Computed Tomography (CoCBCT). Results indicate no significant change in the TVL of high density concrete samples as they cure. The minor fluctuations in shielding properties observed are explained by the heterogeneous structure of the samples as indicated in the CoCBCT images. PMID:23982607
Marsh, Matthew B; Peters, Christopher; Rawluk, Nicholas; Schreiner, L John
Multi-Grid Genetic Algorithms For Optimal Radiation Shield Design
NASA Astrophysics Data System (ADS)
Genetic Algorithms (GA) are a powerful search and optimization technique that can be applied to numerous problems. Unfortunately. GA relies on large numbers of fitness evaluations to determine the relative merits of various solutions to a problem. For problems requiring computationally intensive fitness evaluations this can make GA too expensive to use. We describe a hierarchical technique that we have created called Multi-Grid Genetic Algorithms (MGGA). MGGA leverages the geometry of a problem space to build a hierarchy of increasingly smaller problem spaces. Optimizations over these smaller spaces are used to seed a population of solutions in a larger space. We explore how MGGA can be applied to several radiation shielding problems.
Asbury, Stephen T.
Analytical shielding calculations for a proton therapy facility.
The University of Pennsylvania is building a proton therapy facility in collaboration with Walter Reed Army Medical Center. The proposed facility has four gantry rooms, a fixed beam room and a research room, and will use a cyclotron as the source of protons. In this study, neutron shielding considerations for the proposed proton therapy facility were investigated using analytical techniques and Monte Carlo simulated neutron spectra. Neutron spectra calculations were done using the GEANT4 (v6.2) simulation code for various materials: water, carbon, iron, nickel and tantalum to estimate the neutron production at proton beam energies of 100, 175 and 250 MeV. Dose equivalent calculations were performed using analytical methods at various critical points within the facility, by folding the GEANT4 produced neutron spectra with dose equivalent rate data from the National Council on Radiation Protection and Measurements (NCRP) Report #144. PMID:18487617
Avery, Stephen; Ainsley, Chris; Maughan, Richard; McDonough, James
Additional adjoint Monte Carlo studies of the shielding of concrete structures against initial gamma radiation. Final report
The adjoint Monte Carlo method previously developed by MAGI has been applied to the calculation of initial radiation dose due to air secondary gamma rays and fission product gamma rays at detector points within buildings for a wide variety of problems. These provide an in-depth survey of structure shielding effects as well as many new benchmark problems for matching by
M. Beer; M. O. Cohen
Investigation of neutron shielding efficiency and radioactivity of concrete shields containing colemanite
NASA Astrophysics Data System (ADS)
In this work, colemanite, a boron-bearing ore, was added to ordinary Portland concrete as aggregate. Some concrete blocks containing different amounts of colemanite were produced and their neutron permeability and compressive strength were determined. From the results of the experiments, taking into account the nuclear and structural properties of shielding material, a proper colemanite adding ratio was presented. A neutron transport calculation of the shield containing colemanite was made by using the removal-diffusion technique and the decrease in shield thickness, compared to ordinary Portland concrete, was found. Assuming a 20-year stepwise irradiation, the neutron-induced activity within the shield was calculated. Cooling time after shutdown was taken up to 10 5 years. By comparing the total and elemental activities of the ordinary and colemanite-added Portland concretes, the contribution of colemanite to the shield activity was investigated.
Yarar, Yasemin; Bay�lken, Ahmet
Shielding Structures for Interplanetary Human Mission
NASA Astrophysics Data System (ADS)
Since the end of Apollo missions, human spaceflight has been limited to the Low Earth Orbit (LEO), inside the protective magnetic field of the Earth, because astronauts are, to the largest degree, protected from the harsh radiation environment of the interplanetary space. However, this situation will change when space exploration missions beyond LEO will become the real challenge of the human exploration program. The feasibility of these missions in the solar system is thus strongly connected to the capability to mitigate the radiation-induced biological effects on the crew during the journey and the permanence on the intended planet surface. Inside the International Space Station (ISS), the volumes in which the crew spends most of the time, namely the crew quarters are the only parts that implement dedicated additional radiation shielding made of polyethylene tiles designed for mitigating SPE effects. Furthermore, specific radiation shielding materials are often added to the described configuration to shield crew quarters or the entire habitat example of these materials are polyethylene, liquid hydrogen, etc. but, increasing the size of the exploration vehicles to bring humans beyond LEO, and without the magnetosphere protection, such approach is unsustainable because the mass involved is a huge limiting factor with the actual launcher engine technology. Moreover, shielding against GCR with materials that have a low probability of nuclear interactions and in parallel a high ionizing energy loss is not always the best solution. In particular there is the risk to increase the LET of ions arriving at the spacecraft shell, increasing their Radio-Biological Effectiveness. Besides, the production of secondary nuclei by projectile and target fragmentation is an important issue when performing an engineering assessment of materials to be used for radiation shielding. The goal of this work is to analyze different shielding solutions to increase as much as possible the radiation shielding power of the interplanetary habitat structures, like the spacecraft shell, minimizing the amount of mass used. From the radiation protection point of view the spacecraft shell is an interesting spacecraft system because it surrounds almost homogeneously all the habitat and it is typically composed by the Micrometeorites and Debris Protection Systems (MDPS), the Multilayer Insulation (MLI) for thermal control purposes, and the primary structure that offers the pressure containment functionality. Nevertheless, the spacecraft internal outfitting is important to evaluate the different shielded areas in the habitat. Using Geant4 Monte Carlo simulations toolkit through GRAS (Geant4 Radiation Analysis for Space) tool, different spacecraft structures will be analyzed for their shielding behavior in terms of fluxes, dose reduction and radiation quality, and for their implementation in a real pressurized module. Effects on astronauts and electronic equipments will be also assessed with respect to the standard aluminum structures.
Tracino, Emanuele; Lobascio, Cesare
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
40. SOUTHWEST CORNER OF STAGE SHOWING RIGGING FOR FLYING SETS, LOCATION OF ORIGINAL DOORS IN PROSCENIUM WALL, AND COUNTERWEIGHTS FOR STAGE CURTAIN. - Auditorium Building, 430 South Michigan Avenue, Chicago, Cook County, IL
Asymmetric Electrostatic Radiation Shielding for Spacecraft
NASA Technical Reports Server (NTRS)
A paper describes the types, sources, and adverse effects of energetic-particle radiation in interplanetary space, and explores a concept of using asymmetric electrostatic shielding to reduce the amount of such radiation impinging on spacecraft. Typically, such shielding would include a system of multiple inflatable, electrically conductive spheres deployed in clusters in the vicinity of a spacecraft on lightweight structures that would maintain the spheres in a predetermined multipole geometry. High-voltage generators would maintain the spheres at potential differences chosen in conjunction with the multipole geometry so that the resulting multipole field would gradually divert approaching energetic atomic nuclei from a central region occupied by the spacecraft. The spheres nearest the center would be the most positive, so as to repel the positively charged impinging nuclei from the center. At the same time, the monopole potential of the overall spacecraft-and-shielding system would be made negative so as to repel thermal electrons. The paper presents results of computational simulations of energetic-particle trajectories and shield efficiency for a trial system of 21 spheres arranged in three clusters in an overall linear quadrupole configuration. Further development would be necessary to make this shielding concept practical.
Metzger, Philip T.; Youngquist, Robert C.; Lane, John E.
Advances in space radiation shielding codes
NASA Technical Reports Server (NTRS)
Early space radiation shield code development relied on Monte Carlo methods and made important contributions to the space program. Monte Carlo methods have resorted to restricted one-dimensional problems leading to imperfect representation of appropriate boundary conditions. Even so, intensive computational requirements resulted and shield evaluation was made near the end of the design process. Resolving shielding issues usually had a negative impact on the design. Improved spacecraft shield design requires early entry of radiation constraints into the design process to maximize performance and minimize costs. As a result, we have been investigating high-speed computational procedures to allow shield analysis from the preliminary concept to the final design. For the last few decades, we have pursued deterministic solutions of the Boltzmann equation allowing field mapping within the International Space Station (ISS) in tens of minutes using standard Finite Element Method (FEM) geometry common to engineering design methods. A single ray trace in such geometry requires 14 milliseconds and limits application of Monte Carlo methods to such engineering models. A potential means of improving the Monte Carlo efficiency in coupling to spacecraft geometry is given.
Wilson, John W.; Tripathi, Ram K.; Qualls, Garry D.; Cucinotta, Francis A.; Prael, Richard E.; Norbury, John W.; Heinbockel, John H.; Tweed, John; De Angelis, Giovanni
Large shield volcanoes on the Moon
NASA Astrophysics Data System (ADS)
volcanic style of the Moon has long been understood to consist almost exclusively of flood basalts erupted from fissures along with minor pyroclastic activity; large central vent shield volcanoes that characterize basaltic volcanism on the other terrestrial planets appeared to be absent. Small (few kilometers diameter) central vent constructs have long been recognized in the lunar maria and often are found clustered in fields throughout the lunar maria. New global topographic data from the LOLA and LROC instruments on LRO reveal that almost all of these volcanic complexes on the Moon occur on large, regional topographic rises in the lunar maria, tens to hundreds of kilometers in extent and between several hundred to several thousand meters high. We propose that these topographic swells are shield volcanoes and are the lunar equivalents of the large basaltic shields found on the Earth, Venus, and Mars. The newly recognized lunar shields are found peripheral to the large, deeply flooded impact basins Imbrium and Serenitatis, suggesting a genetic relation to those features. Loading of the lithosphere by these basalt-filled basins may be responsible for inducing a combination of flexural and membrane stress, inducing a pressure distribution on vertically oriented dikes favorable to magma ascent. This condition would occur in a zone annular to the large circular loads produced by the basins, where the shield volcanoes occur.
Spudis, Paul D.; McGovern, Patrick J.; Kiefer, Walter S.
Correlated Uncertainties in Radiation Shielding Effectiveness
NASA Technical Reports Server (NTRS)
The space radiation environment is composed of energetic particles which can deliver harmful doses of radiation that may lead to acute radiation sickness, cancer, and even death for insufficiently shielded crew members. Spacecraft shielding must provide structural integrity and minimize the risk associated with radiation exposure. The risk of radiation exposure induced death (REID) is a measure of the risk of dying from cancer induced by radiation exposure. Uncertainties in the risk projection model, quality factor, and spectral fluence are folded into the calculation of the REID by sampling from probability distribution functions. Consequently, determining optimal shielding materials that reduce the REID in a statistically significant manner has been found to be difficult. In this work, the difference of the REID distributions for different materials is used to study the effect of composition on shielding effectiveness. It is shown that the use of correlated uncertainties allows for the determination of statistically significant differences between materials despite the large uncertainties in the quality factor. This is in contrast to previous methods where uncertainties have been generally treated as uncorrelated. It is concluded that the use of correlated quality factor uncertainties greatly reduces the uncertainty in the assessment of shielding effectiveness for the mitigation of radiation exposure.
Werneth, Charles M.; Maung, Khin Maung; Blattnig, Steve R.; Clowdsley, Martha S.; Townsend, Lawrence W.
Microscreen radiation shield for thermoelectric generator
The present invention provides a microscreen radiation shield which reduces radiative heat losses in thermoelectric generators such as sodium heat engines without reducing the efficiency of operation of such devices. The radiation shield is adapted to be interposed between a reaction zone and a means for condensing an alkali metal vapor in a thermoelectric generator for converting heat energy directly to electrical energy. The radiation shield acts to reflect infrared radiation emanating from the reaction zone back toward the reaction zone while permitting the passage of the alkali metal vapor to the condensing means. The radiation shield includes a woven wire mesh screen or a metal foil having a plurality of orifices formed therein. The orifices in the foil and the spacing between the wires in the mesh is such that radiant heat is reflected back toward the reaction zone in the interior of the generator, while the much smaller diameter alkali metal atoms such as sodium pass directly through the orifices or along the metal surfaces of the shield and through the orifices with little or no impedance.
Hunt, Thomas K. (Ann Arbor, MI); Novak, Robert F. (Farmington Hills, MI); McBride, James R. (Ypsilanti, MI)
NSDL National Science Digital Library
Developed by the Japan Science and Technology Corporation (JST), J-STAGE (The Japan Science and Technology Aggregator, Electronic) is a recently launched electronic journal center that publishes and disseminates Japanese electronic scientific journals. At present, the site hosts four journals (one of which is Japanese only), but expects to add over a hundred in the near future. The three available English-language journals include the Japanese Journal of Applied Physics, the Journal of the Physical Society of Japan, and SHIGEN-TO-SOZAI, a journal of the Mining and Materials Processing Institute of Japan. The full-text articles are available free of charge with searchable back issues also available.
Archaean TTG of Vodlozero Terrain, Fennoscandian Shield
NASA Astrophysics Data System (ADS)
The Vodlozero terrain is the largest (about 270*240 km) early Archaean fragment of Fennoscandian Shield and composes its eastern part. The granitoids of TTG suite are predominant component of the terrain. The greenstone belts are placed along the margins of the terrain. Several stages of TTG formation can be distinguished in Achaean crust history. (1) The oldest TTG are trondhjemites and tonalities with age of 3240 Ma. They contain rare and small amphibolite inclusions of the same age. These TTG are characterized by high Sr (av. 412 ppm), Sr/Y (70), (La/Yb)n (54) and low Y (av. 7 ppm), Yb (0.32 ppm) and Nb (4 ppm). It was shown (Lobach-Zhuchenko et al., 2000), that the source of these TTG could be basic rocks, having composition similar with TH1 by K.Condie. (2) The tonalities and granodiorites with age of 3150 Ma are disposed near greenstone belts and contain compared to TTG of the first group less Sr (av. 250 ppm), Sr/Y (22), (La/Yb)n (18) and more K, Rb (av. 70 ppm), Ba (470 ppm), Y (11 ppm),Yb (1.16 ppm). TTG of both groups have identical T(DM)Nd (3250-3400 Ma) and differences in composition is evidently connected with lower level of source melting of the second group and also with K-metasomatism. The volcanics of the greenstone belts have age 3020 - 2940 Ma. Dykes of gabbro-amphibolites and andesites with the same age and composition cut TTG of the first and the second groups. The age of the third TTG group is about 2900 Ma ago. These rocks form leucosoma of migmatites within TTG of the second group. The composition of the third TTG and Nd isotope data suppose their origin by the melting of ancient TTG crust simultaneously with greenstone belt emplacement. The fourth TTG group with age 2780-2850 Ma forms a small intrusions, cutting older TTG and greenstone rocks. Their composition is similar to 3150 Ma TTG. Nd isotope data indicate that these TTG have younger (about 2850 Ma) source. Thus there are four TTG groups formed into interval more 400 Ma. The age and composition of the rocks indicate on the absence of connection in origin of TTG and volcanics. References Lobach-Zhuchenko S.B., Kovalenko A.V., Krylov I.N., Levsky L.K., Bogomolov E.S. Geochemistry and petrology of the ancient Vygozero Granitoids, Southeastern Karelia // Geochemistry International. 2000. V. 38. S. 1. P. 584-599.
Chekulaev, Valery; Arestova, Natalia
Determination of the radioactive material and plutonium holdup in ducts and piping in the 327 Building.
National Technical Information Service (NTIS)
The 327 Building Post Irradiation Testing Laboratory is used for temporary storage and for destructive and nondestructive examination of irradiated reactor fuels and structural materials. The facility contains 12 shielded hot cells, two water-filled basin...
D. L. Haggard L. W. Brackenbush
Effective shielding is more than a pretty facade
NASA Astrophysics Data System (ADS)
The least understood of many elements which the designer has to consider in connection with electromagnetic compatibility problems is, perhaps, related to shielding. Electromagnetic shields are metallic barriers used to contain or reduce the coupling of electromagnetic energy. Maxwell's equations for time-varying fields can be used for an analysis of the effectiveness of a shielding barrier. However, these equations can become quite complex even for simple models. For this reason, transmission line theory, applied to shielding applications, has been employed to determine total shielding effectiveness. The design of suitable shielding barriers is discussed. The material employed can consist of metal, including high-permeability materials, and plastics with a conductive medium. Attention is given to approaches for accessing the interior of the shielded space, the ideal shielding joint, a reusable sealing method, conductive gaskets, conductive elastomers, correct grounding, the shielding of cables, and the use of waveguides.
Scheps, R. D.
Building a Process-Savvy Organization
ERIC Educational Resources Information Center
Process improvement and organizational development go hand-in-hand. Building out your organizational process infrastructure will provide the tools necessary to build and maintain effective processes. It takes time, effort, and persistence to get through the initial stages, but the foundational steps of process awareness set the stage for later�
Jordan, Tom
High purity silica reflective heat shield development
NASA Technical Reports Server (NTRS)
A hyperpure vitreous silica material is being developed for use as a reflective and ablative heat shield for planetary entry. Various purity grades and forms of raw materials were evaluated along with various processing methods. Slip casting of high purity grain was selected as the best processing method, resulting in a highly reflective material in the wavelength bands of interest (the visible and ultraviolet regions). The selected material was characterized with respect to optical, mechanical and physical properties using a limited number of specimens. The process has been scaled up to produce a one-half scale heat shield (18 in. dia.) (45.72 cm) for a Jupiter entry vehicle. This work is now being extended to improve the structural safety factor of the heat shield by making hyperpure silica material tougher through the addition of silica fibers.
Nachtscheim, P. R.; Blome, J. C.
Electromagnetic Shielding Efficiency Measurement of Composite Materials
NASA Astrophysics Data System (ADS)
This paper deals with the theoretical and practical aspects of the shielding efficiency measurements of construction composite materials. This contribution describes an alternative test method of these measurements by using the measurement circular flange. The measured results and parameters of coaxial test flange are also discussed. The measurement circular flange is described by measured scattering parameters in the frequency range from 9 kHz up to 1 GHz. The accuracy of the used shielding efficiency measurement method was checked by brass calibration ring. The suitability of the coaxial test setup was also checked by measurements on the EMC test chamber. This data was compared with the measured data on the real EMC chamber. The whole measurement of shielding efficiency was controlled by the program which runs on a personal computer. This program was created in the VEE Pro environment produced by � Agilent Technology.
D?�novsk�, J.; Kej�k, Z.
Heating profiles on ICRF antenna Faraday shields
A conceptual design for an uncooled Faraday shield for the BPX ion cyclotron resonance heating (ICRH) antenna, which should withstand the proposed long-pulse operation, has been completed. A high-heat-flux, uncooled Faraday shield has also been designed for the fast-wave current drive (FWCD) antenna on D3-D. For both components, the improved understanding of the heating profiles made it possible to design for heat fluxes that would otherwise have been too close to mechanically established limits. The analytical effort is described in detail, with emphasis on the design work for the BPX ICRH antenna conceptual design and for the replacement Faraday shield for the D3-D FWCD antenna. Results of analyses are shown, and configuration issues involved in component modeling are discussed. 3 refs., 6 figs., 2 tabs.
Taylor, D.J.; Baity, F.W.; Hahs, C.L.; Riemer, B.W.; Ryan, P.M.; Williamson, D.E.
Electronics Shielding and Reliability Design Tools
NASA Technical Reports Server (NTRS)
It is well known that electronics placement in large-scale human-rated systems provides opportunity to optimize electronics shielding through materials choice and geometric arrangement. For example, several hundred single event upsets (SEUs) occur within the Shuttle avionic computers during a typical mission. An order of magnitude larger SEU rate would occur without careful placement in the Shuttle design. These results used basic physics models (linear energy transfer (LET), track structure, Auger recombination) combined with limited SEU cross section measurements allowing accurate evaluation of target fragment contributions to Shuttle avionics memory upsets. Electronics shielding design on human-rated systems provides opportunity to minimize radiation impact on critical and non-critical electronic systems. Implementation of shielding design tools requires adequate methods for evaluation of design layouts, guiding qualification testing, and an adequate follow-up on final design evaluation including results from a systems/device testing program tailored to meet design requirements.
Wilson, John W.; ONeill, P. M.; Zang, Thomas A., Jr.; Pandolf, John E.; Koontz, Steven L.; Boeder, P.; Reddell, B.; Pankop, C.
Vehicle Shield Optimization and Risk Assessment for Future Human Space Missions
NASA Technical Reports Server (NTRS)
As the focus of future human space missions shifts to destinations beyond low Earth orbit such as Near Earth Objects (NEO), the moon, or Mars, risks associated with extended stay in hostile radiation environment need to be well understood and assessed. Since future spacecrafts designs and shapes are evolving continuous assessments of shielding and radiation risks are needed. In this study, we use a predictive software capability that calculates risks to humans inside a spacecraft prototype that builds on previous designs. The software uses CAD software Pro/Engineer and Fishbowl tool kit to quantify radiation shielding provided by the spacecraft geometry by calculating the areal density seen at a certain point, dose point, inside the spacecraft. Shielding results are used by NASA-developed software, BRYNTRN, to quantify organ doses received in a human body located in the vehicle in case of solar particle event (SPE) during such prolonged space missions. Organ doses are used to quantify risks on astronauts health and life using NASA Space Cancer Model. The software can also locate shielding weak points-hotspots-on the spacecraft s outer surface. This capability is used to reinforce weak areas in the design. Results of shielding optimization and risk calculation on an exploration vehicle design for missions of 6 months and 30 months are provided in this study. Vehicle capsule is made of aluminum shell that includes main cabin and airlock. The capsule contains 5 sets of racks that surround working and living areas. Water shelter is provided in the main cabin of the vehicle to enhance shielding in case of SPE.
Nounu, Hatem N.; Kim, Myung-Hee; Cucinotta, Francis A.
Prototype V-Groove Radiator Heat Shield
NASA Technical Reports Server (NTRS)
Report describes design, fabrication, and testing of heat radiator equipped with multi-V-groove radiator heat shield. Device compact, efficient structure which removes heat from infrared detectors, gamma-ray detectors, and similar instruments aboard Mars Observer spacecraft and radiates heat into outer space. Designed to maintain detector for gamma-ray spectrometer at temperature of 80 K in cold vacuum under heat load of 80 mW. Prototype made of aluminum, though production shields made of aluminized sheets of polyethylene terephthalate.
Petrick, S. Walter; Bard, Steven
Tectonic evolution of the Western Australian Shield
NASA Technical Reports Server (NTRS)
Geological and geochronological studies in the Western Australian Shield were updated. This terrane bears many similarities to the Indian Shield since they were neighboring parts of Gondwanaland. Western Australia consists of two cratons (Pilbara and Yilgarn) and four orogenic belts (Capricorn, Pingarra, Albany-Fraser, and Patterson), as well as some relatively young (1.6 to 0.75 Ga) sedimentary rocks. The two cratonic blocks are both older than about 2.5 Ga, and the orogenic belts range in age from 2.0 to 0.65 Ga.
Myers, John S.
Numerical simulation of space debris impacts on the Whipple shield
NASA Astrophysics Data System (ADS)
The authors carried out three series of experimental tests of the first bumper perforation and main wall cratering processes directly caused by three types of projectiles with about 2, 4 and 7 km s -1 impact velocities but comparable initial kinetic energies, by using three different accelerators (one-stage powder gun, two-stage light-gas gun and rail gun), for the purpose of investigating space debris hypervelocity impacts onto single-walled Whipple bumper shields [1]. In the present study, after reviewing the numerical simulation method of hydrocode for both Eulerian and Lagrangian descriptions, a number of parametric numerical simulation analyses using multiple material Eulerian methods were performed in order to optimize the material properties of bumper and main wall materials through comparison with experimental results of single target impacts by the projectiles. In particular, the material data on the dynamic fracture phenomena are discussed in detail in the first part. Then a couple of numerical calculations using the interactive Lagrangian rezoning method to simulate the overall impact process against the single walled Whipple shield were performed and compared with the corresponding experimental results. Both results indicated fairly good agreement with each other. Moreover, it was demonstrated that the present method is helpful and efficient in understanding the impact phenomena and fracture mechanism in the space debris hypervelocity impact problem. Finally the multiple material Eulerian method was applied to the same problems modeled by the interactive Lagrangian rezoning method used previously, because the former is much easier to use for almost all users, although it is more diffusive and unclear of material boundaries than the latter. Those two kinds of numerical results also indicated fairly good agreements with each other.
Katayama, M.; Toda, S.; Kibe, S.
Design and Development of an In-Space Deployable Sun Shield for the Atlas Centaur
NASA Technical Reports Server (NTRS)
The Centaur, by virtue of its use of high specific-impulse (Isp) LO2/LH2 propellants, has initial mass-to-orbit launch requirements less than half of those upper stages using storable propellants. That is, for Earth escape or GSO missions the Centaur is half the launch weight of a storable propellant upper stage. A drawback to the use of Liquid oxygen and liquid hydrogen, at 90 K and 20 K respectively, over storable propellants is the necessity of efficient cryogen storage techniques that minimize boil-off from thermal radiation in space. Thermal blankets have been used successfully to shield both the Atlas Centaur and Titan Centaur. These blankets are protected from atmospheric air loads during launch by virtue of the fact that the Centaur is enclosed within the payload fairing. The smaller Atlas V vehicle, the Atlas 400, has the Centaur exposed to the atmosphere during launch, and therefore, to date has not flown with thermal blankets shielding the Centaur. A design and development effort is underway to fly a thermal shield on the Atlas V 400 vehicle that is not put in place until after the payload fairing jettisons. This can be accomplished by the use of an inflatable and deployable thermal blanket referred to as the Centaur Sun Shield (CSS). The CSS design is also scalable for use on a Delta upper stage, and the technology potentially could be used for telescope shades, re-entry shields, solar sails and propellant depots. A Phase I effort took place during 2007 in a partnership between ULA and ILC Dover which resulted in a deployable proof-of-concept Sun Shield being demonstrated at a test facility in Denver. A Phase H effort is underway during 2008 with a partnership between ULA, ILC, NASA Glenn Research Center (GRC) and NASA Kennedy Space Center (KSC) to define requirements, determine materials and fabrication techniques, and to test components in a vacuum chamber at cold temperatures. This paper describes the Sun Shield development work to date, and the future plans leading up to a flight test in the 2011 time frame.
Dew, Michael; Allwein, Kirk; Kutter, Bernard; Ware, Joanne; Lin, John; Madlangbayan, Albert; Willey, Cliff; Pitchford, Brian; O'Neil, Gary
75 FR 57519 - Weather Shield Manufacturing, Medford, WI; Notice of Negative Determination Regarding Application...
Federal Register 2010, 2011, 2012, 2013
...673] Weather Shield Manufacturing, Medford, WI; Notice...workers of Weather Shield Manufacturing, Inc., Medford, Wisconsin (subject firm). The negative determination...various Weather Shield Manufacturing, Inc....
The Effic,acy of Farabloc, An Electromagnetic Shield, in Attenuating Delayed-Onset Muscle Soreness
Objective: To assess the hypothesis that Farabloc, a fabric with electromagnetic shielding properties, would attenuate the symptoms, signs, and muscular strength deficit secondary to delayed-onset muscle soreness (DOMS) induced by two expo� sures to eccentric exercise in humans. Design: Randomized, single-blind, placebo-controlled, crossover trial with two testing stages of 5 days duration sepa� rated by a washout period of more
Jian Zhang; Douglas Clement; Jack Taunton
This masonry office building in the downtown area of Concepcion, Chile collapsed as a result of the M 8.8 earthquake on Feb. 27, 2010. The construction of this building predates the establishment of strict building codes in Chile, put in place following the devastating earthquake of 1960. ...
ERIC Educational Resources Information Center
Health problems related to school buildings can be categorized in five major areas: sick-building syndrome; health-threatening building materials; environmental hazards such as radon gas and asbestos; lead poisoning; and poor indoor air quality due to smoke, chemicals, and other pollutants. This paper provides an overview of these areas,�
Grubb, Deborah
Effects of bumper size on high velocity impact damage to Whipple shield
NASA Astrophysics Data System (ADS)
With the increasing number of space mission the impact risk on spacecraft at hypervelocity by space debris is increasing A collision with space debris can cause damage to a spacecraft in low Earth orbit For designing spacecraft protection constructions and developing advanced debris shieldsLhypervelocity impact simulation experiments on the ground and the computer simulation of hypervelocity impact is the important means The choice of shields modle sizes is a important step both in the experiments and computer simulation Whipple shields are the basic structure configuration for protecting spacecraft from meteoroid and orbital debris and are still extensively adopted This paper explores the bumper size effects on the damage produced by high velocity impacts on Wipple shields Tests were performed using the non-powder two-stage light gas gun facilities at Hypervelocity Impact Research Center at Harbin Institute of Technology The configuration of Wipple shields consisted of various sizes 1 mm thickness bumpers and constant size 3 mm thickness rear wall with 10 cm space btween the bumper and the rear wall The bumpers used for the tests were made up of 8 12 16 and 20 cm square plate made from 2A12 Aluminum All tests were performed with 4 mm in diameter aluminum projectile at velocity ranging from 1 45 to 1 71 km s The limit velocity of projectile impacting on the Whipple shields in over 0 8 probability of penetration of rear wall in probability of no-penetration of rear wall and on critical penetration condition of rear wall was shown to
Ha, Y.; Guan, G. S.; Pang, B. J.; Zhang, W.
Reflectivity level of RF shielded anechoic chamber
The reflectivity level of an RF shielded rectangular chamber with a non-uniform absorber lining has been investigated using the geometrical optics approach. The excitation antennas considered are the Hertzian dipole, a halfwave dipole and a pyramidal horn. A simple model is employed for the reflectivity of the absorber lining for normal incidence
S. V. K. Shastry; S. K. Nagesh; D. Binu
Operation Desert Shield and Desert Storm.
National Technical Information Service (NTIS)
So what did you do in the War, Daddy. As a Battalion Commander of an AH-64 Attack Helicopter Battalion during Operations Desert Shield and Desert Storm, my experiences were many, my memories everlasting. Rather than enumerate a chronology of events, I wil...
A. R. Jones
Shielding Integral Benchmark Archive and Database (SINBAD)
The Shielding Integral Benchmark Archive and Database (SINBAD) collection of benchmarks was initiated in the early 1990s. SINBAD is an international collaboration between the Organization for Economic Cooperation and Development's Nuclear Energy Agency Data Bank (OECD\\/NEADB) and the Radiation Safety Information Computational Center (RSICC) at Oak Ridge National Laboratory (ORNL). SINBAD is a major attempt to compile experiments and corresponding
Bernadette Lugue Kirk; Robert E Grove; I. Kodeli; Enrico Sartori; J. Gulliford
Shielding and Density of States in Alloys.
National Technical Information Service (NTIS)
A relationship between the shielding of the ion-core potentials and the electron density of states rho(E,c) in disordered alloys of concentration c is shown. When one type of atom in a binary disordered alloy is replaced by another type of atom, there wil...
E. A. Stern
Shielding Design for PWR in France.
National Technical Information Service (NTIS)
Shielding calculation scheme used in France for PWR is presented here for 900 MWe and 1300 MWe plants built by EDF the French utility giving electricity. Neutron dose rate at areas accessible by personnel during the reactor operation is calculated and com...
G. Champion Charransol A. Le Dieu de Ville J. C. Nimal T. Vergnaud
Corrosion protection and EMP/EMI shielding
The high-voltage electrical surges which are released from nuclear explosions are called electromagnetic pulses (EMP). Because they can have adverse effects on aircraft and other weapon system electrical circuits, the DOD has evaluated a variety of approaches to providing protection against EMP and electromagnetic interference (EMI). Researchers are now working to develop conductive sealants which can provide corrosion protection while meeting the EMP/EMI shielding requirements of military aircraft and missiles. Test results indicate that shielding effectiveness increases as dc resistance decreases, and shielding effectiveness does not appear to be a strong function of frequency above the 500-1000 MHz test frequency range. The correlations of resistance and shielding effectiveness necessitates that a low resistance exists across a joint or bond. Thus the researchers recommended that the conductive sealants successfully tested be used on existing and future aircraft and missiles where sealants can be liquid-applied. In addition to the test findings and their applications to the operational arena, a primary outcome of these tests is a set of recommended changes to selected military standards, specifications, and handbooks. These recommendations will be used as inputs to any proceedings conducted for the purpose of modifying those documents.
Brahney, J.H.
Passive magnetic shielding in static gradient fields
NASA Astrophysics Data System (ADS)
The effect of passive magnetic shielding on dc magnetic field gradients imposed by both external and internal sources is studied for two idealized shield models: concentric spherical and infinitely-long cylindrical shells of linear material. It is found that higher-order multipoles of an externally applied magnetic field are always shielded progressively better for either geometry by a factor related to the order of the multipole. In regard to the design of internal coil systems, we determine reaction factors for the general multipole field and provide examples of how one can take advantage of the coupling of the coils to the innermost shell to optimize the uniformity of the field. Furthermore, we provide formulae relevant to active magnetic compensation systems which attempt to stabilize the interior fields by sensing and cancelling the exterior fields close to the outermost shell. Overall this work provides a comprehensive framework that is useful for the analysis and optimization of dc magnetic shields, serving as a theoretical and conceptual design guide as well as a starting point and benchmark for finite-element analysis.
Bidinosti, C. P.; Martin, J. W.
Subsurface Shielding Source Term Specification Calculation
The purpose of this calculation is to establish appropriate and defensible waste-package radiation source terms for use in repository subsurface shielding design. This calculation supports the shielding design for the waste emplacement and retrieval system, and subsurface facility system. The objective is to identify the limiting waste package and specify its associated source terms including source strengths and energy spectra. Consistent with the Technical Work Plan for Subsurface Design Section FY 01 Work Activities (CRWMS M&O 2001, p. 15), the scope of work includes the following: (1) Review source terms generated by the Waste Package Department (WPD) for various waste forms and waste package types, and compile them for shielding-specific applications. (2) Determine acceptable waste package specific source terms for use in subsurface shielding design, using a reasonable and defensible methodology that is not unduly conservative. This calculation is associated with the engineering and design activity for the waste emplacement and retrieval system, and subsurface facility system. The technical work plan for this calculation is provided in CRWMS M&O 2001. Development and performance of this calculation conforms to the procedure, AP-3.12Q, Calculations.
New shielding protective equipment for live working
The new protective equipment forms a FARADAY cage, thus protecting the worker from unacceptably strong electrical fields as well as from being invaded by dangerous electric currents. The protective shielding clothing described is a personal protective equipment of the highest category. Therefore, it must be certified by an acknowledged examining and certifying authority. An application with regard to the attestation
Claudia Herzberg; Hartmut R�del; Eberhard Engelmann
Radiation Shielding Analysis for Deep Space Missions
An environment for radiation shielding analysis for manned deep space mission scenarios has been developed. The analysis is performed by dividing a mission scenario into three possible different phases, namely the interplanetary cruise phase, the final planetary approach and orbit insertion, and the surface phase. In the first phase only Galactic Cosmic Rays and Solar Events particles are used, in
Giovanni de Angelis; Martha S. Clowdsley; John E. Nealy; Robert C. Singleterry; Ram K. Tripathi; John W. Wilson
SCALE radiation shielding V and V package
Verification and validation (V and V) are essential elements of software quality assurance (QA) for computer codes that are used for scientific calculations. The sponsors of the SCALE code system have required a QA plan and a V and V plan. For purposes of validating and verifying the SCALE shielding codes, a set of problems has been assembled and tested.
Emmett, M.B.; Bowman, S.M.; Broadhead, B.L.
Shielded serpentine traveling wave tube deflection structure.
National Technical Information Service (NTIS)
This invention is comprised of a shielded serpentine slow wave deflection structure having a serpentine signal conductor within a channel groove. The channel groove is formed by a serpentine channel in a trough plate and a ground plane. The serpentine sig...
C. L. Hudson J. Spector
Optimization For Whipple Shields Under Normal Impact
An engineering structural optimization methodology of Whipple Shields is developed designed to defeat hypervelocity impacts of meteoroids and space debris. The major unique of the optimization model presented in the paper is that Hypervelocity Impact Physical Model based on One-Dimension Impact Theory is incorporated into the previous optimization model. A space debris environment model is incorporated into an overall optimization
Song Lin; Yuzhu Zhang; Renwei Xia
Hermetic Sealing and EMI Shielding Gasket.
National Technical Information Service (NTIS)
A composition is disclosed for forming an EMI shielding gasket for installation against a metal object, such as an aluminum frame member of an aircraft, wherein the composition is comprised of a mixture of a prepolymer composition of a flexible polyuretha...
R. Panayappan J. C. Cooper
Nuclear physics issues in radiation shielding assessment
Protecting the astronauts from the adverse health effects of galactic cosmic radiation is a complicated issue because of uncertainty in the physics of interactions with the nuclei of shielding materials and astronaut tissues. Semi-classical Monte Carlo methods have shown reasonable success and can include quantum fluctuations but lack phase information for evaluation of diffractive and interference effects in the asymptotic
John Wilson; Ram Tripathi; Francis Cucinotta; John Norbury
The Tower Shielding Facility: Its glorious past
The Tower Shielding Facility (TSF) is the only reactor facility in the US that was designed and built for radiation-shielding studies in which both the reactor source and shield samples could be raised into the air to allow measurements to be made without interference from ground scattering or other spurious effects. The TSF proved its usefulness as many different programs were successfully completed. It became active in work for the Defense Atomic Support Agency (DASA) Space Nuclear Auxiliary Power, Defense Nuclear Agency, Liquid Metal Fast Breeder Reactor Program, the Gas-Cooled and High-Temperature Gas-Cooled Reactor programs, and the Japanese-American Shielding Program of Experimental Research, just to mention a few of the more extensive ones. The history of the TSF as presented in this report describes the various experiments that were performed using the different reactors. The experiments are categorized as to the programs which they supported and placed in corresponding chapters. The experiments are described in modest detail, along with their purpose when appropriate. Discussion of the results is minimal, but references are given to more extensive topical reports.
Muckenthaler, F.J.
NSDL National Science Digital Library
The University of California at Berkeley's English Department has undertaken the enormous task of presenting "a survey of current information, opinions and visuals about...the original nature of Shakespearean performance during his lifetime, and of its development through four centuries thereafter." Visitors can click on "Performance Galleries" at the top of the homepage to be taken to ten albums of over 900 images. Some of the topics of the albums that you can link to are "Productions from the Sixteenth through the Twentieth Century", "Productions in Britain 1960-1998", and "Unusual Representations of Shakespeare Performances". The albums contain items such as playbills, photos and drawings of performances, and photos of the rebuilt Globe Theatre. On the far left side of the homepage, visitors can click on "Videos" to view a documentary series about Elizabethan life, as well as excerpts of performances staged by the Shakespeare Program of UC Berkeley at Shakespeare's Globe Theatre. The videos can be viewed by "Latest", "Most Viewed", "Highest Rated", and "Featured". Visitors interested in other websites that explore Shakespeare performance will want to click on "Relevant Websites" on the far left side of the homepage, to access a link that has 27 Shakespeare performance related websites.
Shielding analysis of the long length contaminated equipment transportation package
A shielding analysis of a potential long length contaminated equipment transportation package was completed. The analysis was performed to support the design of the transportation package and external shielding.
Nelson, J.V., Westinghouse Hanford
6. View shows Shield 11, looking west. Typical concrete debris ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
6. View shows Shield 11, looking west. Typical concrete debris shield. - Lake Hodges Flume, Along San Dieguito River between Lake Hodges & San Dieguito Reservoir, Rancho Santa Fe, San Diego County, CA
Internal Shield Ground Adapter for Kickpipe/Stuffing Tubes.
National Technical Information Service (NTIS)
The present invention generally relates to electrical grounding equipment and more particularly to a shield ground adapter (SGA) designed to shunt high level electromagnetic (EM) energy from cable shields to a metallic boundary such as kickpipe/stuffing t...
D. S. Dixon
Neutron shielding material based on colemanite and epoxy resin.
In recent years, there has been a need for compact shielding design such as self-shielding of a PET cyclotron or upgradation of radiation machinery in existing facilities. In these cases, high performance shielding materials are needed. Concrete or polyethylene have been used for a neutron shield. However, for compact shielding, they fall short in terms of performance or durability. Therefore, a new type of neutron shielding material based on epoxy resin and colemanite has been developed. Slab attenuation experiments up to 40 cm for the new shielding material were carried out using a 252Cf neutron source. Measurement was carried out using a REM-counter, and compared with calculation. The results show that the shielding performance is better than concrete and polyethylene mixed with 10 wt% boron oxide. From the result, we confirmed that the performance of the new material is suitable for practical use. PMID:16381724
Okuno, Koichi
Light shield and cooling apparatus. [high intensity ultraviolet lamp
NASA Technical Reports Server (NTRS)
A light shield and cooling apparatus was developed for a high intensity ultraviolet lamp including water and high pressure air for cooling and additional apparatus for shielding the light and suppressing the high pressure air noise.
Meador, T. G., Jr. (inventor)
Early test facilities and analytic methods for radiation shielding: Proceedings
This report represents a compilation of eight papers presented at the 1992 American Nuclear Society/European Nuclear Society International Meeting. The meeting is of special significance since it commemorates the fiftieth anniversary of the first controlled nuclear chain reaction. The papers contained in this report were presented in a special session organized by the Radiation Protection and Shielding Division in keeping with the historical theme of the meeting. The paper titles are good indicators of their content and are: (1) The origin of radiation shielding research: The Oak Ridge experience, (2) Shielding research at the hanford site, (3) Aircraft shielding experiments at General Dynamics Fort Worth, 1950-1962, (4) Where have the neutrons gone , a history of the tower shielding facility, (5) History and evolution of buildup factors, (6) Early shielding research at Bettis atomic power laboratory, (7) UK reactor shielding: then and now, (8) A very personal view of the development of radiation shielding theory.
Ingersoll, D.T. (comp.) (Oak Ridge National Lab., TN (United States)); Ingersoll, J.K. (comp.) (Tec-Com, Knoxville, TN (United States))
Active Shielding in Measurements of DC Near Biomagnetic Fields.
National Technical Information Service (NTIS)
Measurements of DC near biomagnetic fields are disturbed by low frequency noise, that are not reduced sufficiently by most of the magnetically shielded rooms or gradiometers. An effective SQUID based active shielding system has been developed and installe...
H. Nowak J. Haueisen M. Ziolkowski F. Resmer J. Schueler
Opportunity's Heat Shield in Color, Sol 335
NASA Technical Reports Server (NTRS)This image from the panoramic camera on NASA's Mars Exploration Rover Opportunity features the remains of the heat shield that protected the rover from temperatures of up to 2,000 degrees Fahrenheit as it made its way through the martian atmosphere. This two-frame mosaic was taken on the rover's 335th martian day, or sol, (Jan. 2, 2004). The view is of the main heat shield debris seen from approximately 10 meters (about 33 feet) away from it. Many rover-team engineers were taken aback when they realized the heat shield had inverted, or turned itself inside out. The height of the pictured debris is about 1.3 meters (about 4.3 feet). The original diameter was 2.65 meters (8.7 feet), though it has obviously been deformed. The Sun reflecting off of the aluminum structure accounts for the vertical blurs in the picture. The fact that the heat shield is now inside out makes it more challenging to evaluate the state of the thermal protection system that is now on the inside. In coming sols, Opportunity will investigate the debris with its microscopic imager. Engineers who designed and built the heat shield are thrilled to see the hardware on the surface of Mars. This provides a unique opportunity to look at how the thermal protection system material survived the actual Mars entry. Team members hope this information will allow them to compare their predictions to what really happened. The image is an approximately true-color rendering generated using the panoramic camera's 600, 530 and 480 nanometer filters.
High-Flux, High-Temperature Thermal Vacuum Qualification Testing of a Solar Receiver Aperture Shield
NASA Technical Reports Server (NTRS)
As part of the International Space Station (ISS) Phase 1 program, NASA Lewis Research Center (LERC) and the Russian Space Agency (RSA) teamed together to design, build and flight test the world's first orbital Solar Dynamic Power System (SDPS) on the Russian space station Mir. The Solar Dynamic Flight Demonstration (SDFD) program was to operate a nominal 2 kWe SDPS on Mir for a period up to 1-year starting in late 1997. Unfortunately, the SDFD mission was demanifested from the ISS phase 1 shuttle program in early 1996. However, substantial flight hardware and prototypical flight hardware was built including a heat receiver and aperture shield. The aperture shield comprises the front face of the cylindrical cavity heat receiver and is located at the focal plane of the solar concentrator. It is constructed of a stainless steel plate with a 1-m outside diameter, a 0.24-m inside diameter and covered with high-temperature, refractory metal Multi-Foil Insulation (MFI). The aperture shield must minimize heat loss from the receiver cavity, provide a stiff, high strength structure to accommodate shuttle launch loads and protect receiver structures from highly concentrated solar fluxes during concentrator off-pointing events. To satisfy Mir operational safety protocols, the aperture shield was required to accommodate direct impingement of the intensely concentrated solar image for a 1-hour period. To verify thermal-structural durability under the anticipated high-flux, high-temperature loading, an aperture shield test article was constructed and underwent a series of two tests in a large thermal vacuum chamber configured with a reflective, point-focus solar concentrator and a solar simulator. The test article was positioned near the focal plane and exposed to concentrated solar flux for a period of 1-hour. In the first test, a near equilibrium temperature of 1862 K was attained in the center of the shield hot spot. In the second test, with increased incident flux, a near equilibrium temperature of 2072 K was achieved. The aperture shield sustained no visible damage as a result of the exposures. This paper describes the aperture shield thermal-vacuum qualification test program including the test article, test facility, procedures, data collection, test success criteria, results and conclusions.
Kerslake, Thomas W.; Mason, Lee S.; Strumpf, Hal J.
Electromagnetic interference shielding mechanisms of CNT\\/polymer composites
The electromagnetic interference (EMI) shielding mechanisms of multi-walled carbon nanotube (MWCNT)\\/polymer composites were analyzed experimentally and theoretically. For the experimental analysis, EMI shielding effectiveness (SE) of MWCNT\\/polypropylene (PP) composite plates made in three different thicknesses and at four different concentrations were studied. A model based on the shielding of electromagnetic plane wave was used to theoretically study the EMI shielding
Mohammed H. Al-Saleh; Uttandaraman Sundararaj
Effective shielding to measure beam current from an ion sourcea)
NASA Astrophysics Data System (ADS)
To avoid saturation, beam current transformers must be shielded from solenoid, quad, and RFQ high stray fields. Good understanding of field distribution, shielding materials, and techniques is required. Space availability imposes compact shields along the beam pipe. This paper describes compact effective concatenated magnetic shields for IFMIF-EVEDA LIPAc LEBT and MEBT and for FAIR Proton Linac injector. They protect the ACCT Current Transformers beyond 37 mT radial external fields. Measurements made at Saclay on the SILHI source are presented.
Bayle, H.; Delferri�re, O.; Gobin, R.; Harrault, F.; Marroncle, J.; Sen�e, F.; Simon, C.; Tuske, O.
Development of shielding design code for synchrotron radiation beam line
NASA Astrophysics Data System (ADS)
For the purpose of application to shielding design calculation for beam lines of SPring-8, a 8 GeV class synchrotron radiation facility of Japan, a new shielding code, STAC-8, has been developed on the basis of a shielding design code, PHOTON. Preliminary shielding calculation for the pilot beam lines of SPring-8 is performed with STAC-8. Validity of the code is verified by comparing its calculation with those using a Monte Carlo code EGS4 and PHOTON.
Asano, Yoshihiro; Sasamoto, Nobuo
500 kV shield wires; Sectionalize or ground everywhere
The primary purpose of shield wires on transmission lines in lightning protection. Development of fiber-optic shied wires added communications capabilities. Schemes for adapting fiber-optic shield wires to sectionalized shield wire designs remain untested. It is a present policy to segment and insulate 500 kV shield wires. Computer modeling and supportive field measurements have revealed a characteristic distribution of grounded tower
Designing dual-plate meteoroid shields: A new analysis
NASA Technical Reports Server (NTRS)
Physics governing ultrahigh velocity impacts onto dual-plate meteor armor is discussed. Meteoroid shield design methodologies are considered: failure mechanisms, qualitative features of effective meteoroid shield designs, evaluating/processing meteoroid threat models, and quantitative techniques for optimizing effective meteoroid shield designs. Related investigations are included: use of Kevlar cloth/epoxy panels in meteoroid shields for the Halley's Comet intercept vehicle, mirror exposure dynamics, and evaluation of ion fields produced around the Halley Intercept Mission vehicle by meteoroid impacts.
Swift, H. F.; Bamford, R.; Chen, R.
Magnetic field concentration: comparison between several shapes of superconducting shields
This paper deals with a system of flux density concentration using superconducting shields. The development of single grain high, temperature superconductors allows the conception of large sized magnetic shields. These shields force the flux density to be concentrated by modifying its spatial distribution. The authors' system consists of two low field solenoids, which have the same arrangement as Helmoltz coils.
P. Masson; D. Netter; J. Leveque; A. Rezzoug
Dose buildup factor formula for double-layered shields
In radiation shielding, health physics, and radioactive waste management, it is very important to know buildup factors for various materials and their combinations used as multilayer shields. In this work, a general formula that computes buildup factors for double-layer shields was developed on the basis of Monte Carlo photon transport using the MCNP code. Formulas for buildup factors for double-layer
M. Guvendik; N. Tsoulfanidis
Shrinkable sleeve eliminates shielding gap in RF cable
NASA Technical Reports Server (NTRS)
RF shielding gap between an RF cable and a multipin connector is eliminated by a sleeve assembly installed between the connector and the terminated portion of the shielding. The assembly is enclosed in a heat-shrinkable plastic sleeve which completes the continuous RF shield.
Shielding design for the proposed Advanced Photon Source at Argonne
Bulk shielding was designed for the proposed Argonne Advanced Photon Source. The shielding is for two linacs, the positron converter, booster synchrotron, and the storage ring. Shielding design limits exposure to 20 mrem\\/wk for occupational and 25 mrem\\/y for an individual member of the public from the radiation products, which include high energy neutrons (HEN), giant resonance neutrons (GRN), and
H. J. Moe; V. R. Veluri
Analytical formulation for the shielding effectiveness of enclosures with apertures
An analytical formulation has been developed for the shielding effectiveness of a rectangular enclosure with an aperture. Both the magnetic and electric shielding may be calculated as a function of frequency, enclosure dimensions, aperture dimensions and position within the enclosure. Theoretical values of shielding effectiveness are in good agreement with measurements. The theory has been extended to account for circular
Martin Paul Robinson; Trevor M. Benson; Christos Christopoulos; John F. Dawson; M. D. Ganley; A. C. Marvin; S. J. Porter; David W. P. Thomas
Application of Modal Analysis to Braided-Shield Cables
Transmission-line equations are derived for a braidedshield cable by modal analysis. The parameters of the braided shield appear in the coefficients as well as in the source terms of the equations. The source terms also depend on the currents and charges on the outer surface of the shield with all the shield's apertures shortcircuited.
K. S. H. Lee; CARL E. BAUM
21 CFR 886.4750 - Ophthalmic eye shield.
Code of Federal Regulations, 2013 CFR
...2013-04-01 2013-04-01 false Ophthalmic eye shield. 886.4750 Section 886.4750...Surgical Devices § 886.4750 Ophthalmic eye shield. (a) Identification. An ophthalmic eye shield is a device that consists of a...
Three dimensional hypervelocity impact simulation for orbital debris shield design
This paper assesses a Whipple shield impact simulation method which is both accurate and computationally efficient. The paper documents the simulation methodology and results of Whipple shield simulations at an oblique impact angle of 30�. These results are compared with HVI experiments to demonstrate the accuracy of the simulation technique. In addition, simulations of Whipple shields in the velocity regime
Justin H. Kerr; Eric P. Fahrenthold
Ballistic limit evaluation of advanced shielding using numerical simulations
The advanced shielding concept employed for the Columbus module of the International Space Station consists of an aluminum bumper and an intermediate shield of Nextel and Kevlar-epoxy. Until recently, the lack of adequate material models for the Nextel cloth and Kevlar-epoxy has precluded the practical usage of hydrocodes in evaluating the response of these shields to hypervelocity impact threats. Recently
Colin J. Hayhurst; Iain H. G. Livingstone; Richard A. Clegg; Roberto Destefanis; Moreno Faraud
Large Scale Spheromak for Magnetic Shielding of Spacecraft
Exposure to the energetic particles associated with solar energetic particle events and galactic cosmic rays are known radiation hazards for human exploration. Material shielding would add substantial mass to the spacecraft and provide shielding over very limited areas. The concept that will be explored here is the prospect of providing the shielding by making use of ambient low density plasma
John Slough
Shielding Analyses for Design of the Upgraded JRR-3 Research Reactor, 2. Shielding of Neutron Beam Holes.
National Technical Information Service (NTIS)
Shielding analyses of neutron beam holes have been presented for the shield design of the upgraded JRR-3 research reactor. Description is given about the calculational procedures and results for the standard beam hole, the beam hole for neutron radiograph...
T. Ise T. Maruo Y. Miyasaka M. Isshiki T. Kumai
Evidence-Based Gallbladder Cancer Staging
Background: A recent revision of the American Joint Committee on Cancer (AJCC) staging for gallbladder cancer (6th Edition) involved some major changes. Most notably, T2N0M0 tumors were moved from stage II to stage IB; T3N1M0 disease was moved from stage III to stage IIB; and T4NxM0 (x = any) tumors were moved from stage IVA to stage III. Methods: In order to determine if these changes were justified by data, an analysis of the 10,705 cases of gallbladder cancer collected between 1989 and 1996 in the NCDB was performed. All patients had >5 year follow-up. Results: The staging according to the 6th Edition provided no discrimination between stage III and IV. Five-year survivals for stage IIA, IIB, III, and IV (6th Edition) were 7%, 9%, 3%, 2% respectively. The data from the National Cancer Database (NCDB) were used to derive a proposed new staging system that builds upon Edition 5 and had improved discrimination of stage groups over previous editions. Conclusions: Changes in staging systems should be justified by data. Multicenter databases, including the NCDB, represent important resources for verification of evidence-based staging systems.
Fong, Yuman; Wagman, Lawrence; Gonen, Mithat; Crawford, James; Reed, William; Swanson, Richard; Pan, Charlie; Ritchey, Jamie; Stewart, Andrew; Choti, Michael
How stable are the 'stable ancient shields'?
NASA Astrophysics Data System (ADS)
"Archean cratons are relatively flat, stable regions of the crust that have remained undeformed since the Precambrian, forming the ancient cores of the continents" (King, EPSL, 2005). While this type of statement is supported by a wealth of constraints in the case of episodes of thoroughgoing ductile deformation affecting shield regions of Archean and also Peleoproterozoic age, a growing amount of research indicates that shields are not nearly as structurally stable within the broad field of environmental conditions leading to brittle deformation. In fact, old crystalline basements usually present compelling evidence of long brittle deformation histories, often very complex and challenging to unfold. Recent structural and geochronological studies point to a significant mechanical instability of the shield areas, wherein large volumes of 'stable' rocks actually can become saturated with fractures and brittle faults soon after regional cooling exhumes them to below c. 300-350� C. How cold, rigid and therefore strong shields respond to applied stresses remains, however, still poorly investigated and understood. This in turn precludes a better definition of the shallow rheological properties of large, old crystalline blocks. In particular, we do not yet have good constraints on the mechanisms of mechanical reactivation that control the partial (if not total) accommodation of new deformational episodes by preexisting structures, which remains a key to untangle brittle histories lasting several hundred Myr. In our analysis, we use the Svecofennian Shield (SS) as an example of a supposedly 'stable' region with Archean nucleii and Paleoproterozoic cratonic areas to show how it is possible to unravel the details of brittle histories spanning more than 1.5 Gyr. New structural and geochronological results from Finland are integrated with a review of existing data from Sweden to explore how the effects of far-field stresses are partitioned within a shield, which was growing progressively saturated with fractures as time passed from its initial consolidation. The comparison of time-constrained paleostress data derived from three different locations of the shield shows a remarkably similar stress evolution through time, despite the different geological frameworks of the investigated areas. This suggests that the southern SS has behaved as a coherent rigid crustal block since the Late Mesoproterozoic. By that time, the SS had already reached structural maturity with respect to the saturation of brittle structural features. Therefore, structural reactivation rather than generation of new faults and fractures is the key mechanism that has controlled the mechanical evolution of the shield and that will steer its future evolution within the brittle regime. Comparable brittle structural histories within parts of the shield that are far apart also imply that far-field stresses can propagate over large distances and can lead to similar deformational histories, with the local geological conditions only playing a second-order role on the final brittle strain pattern recorded by the rock.
Viola, Giulio; Mattila, Jussi
Measured neutron beam line shielding effectiveness of several iron/polyethylene configurations
Neutron and gamma-ray leakage measurements were taken at various stages of shield construction of neutron flight path 5 (the Lash-up flight path) at LANSCE, to compare the relative effectiveness of several configurations. Dose equivalent rates were determined for three categories: ''low-energy neutrons'', below 20 MeV; ''high- energy neutrons'', above 20 MeV; and gamma rays, as measured by hand-held survey instruments. The low energy neutrons were measured by activation of an indium foil in a paraffin-filled cadmium canister, sized to be generally insensitive above 20 MeV. High-energy neutrons were measured by (n,2n) production of Carbon 11 in a plastic scintillator with a 20-MeV threshold. Thermal neutrons were not measured at the shield-leakage test points. Room-scattered neutrons were observed by Albatross IV detector readings, which were taken beside the shield as a measure of variation of room background as the shield configuration changed. 1 fig., 1 tab.
Legate, G.L.; Howe, M.L.; Mundis, R.L.
Influence of whole body irradiation and local shielding on matrix-induced endochondral bone differentiation
Subcutaneous implantation of demineralized bone matrix into allogeneic rats induces endochondral bone formation. We have investigated the effects of irradiation on the sequelae of the interaction of collagenous matrix and mesenchymal cells and on cartilage and bone differentiation. Rats were irradiated in a vertical direction with a midline dose of 850 rad. Radiation entered the rats ventrally while a small area of the upper thorax was locally shielded. After irradiation, bone matrix was implanted in shielded and nonshielded sites, and the implants were studied at various stages. On day 3, (3H)thymidine incorporation, an index of cell proliferation, was inhibited by 70% in the nonshielded sites compared to nonirradiated control rats. The degree of inhibition (35%) was less pronounced in shielded sites. Furthermore, there was recovery of cell proliferation in the shielded sites as opposed to the nonshielded contralateral site. A similar pattern was observed on day 7 as assessed by 35SO4 incorporation into proteoglycans during chondrogenesis. Bone formation and mineralization were quantified on day 11 by alkaline phosphatase activity and 45Ca incorporation. In nonshielded sites, there was a 73% inhibition of alkaline phosphatase activity. In conclusion, radiation impaired progenitor cell proliferation which resulted in decreased cartilage and bone differentiation. These findings imply that local mesenchymal cells proliferate and differentiate into bone in response to implanted collagenous matrix.
Wientroub, S.; Weiss, J.F.; Catravas, G.N.; Reddi, A.H. (National Institute of Dental Research, Bethesda, MD (USA))
Conditions of Exciting Coils Used in Evaluation of Shielding Factor of Magnetically Shielded Rooms for Uniform Magnetic Field
To shield the environmental magnetic noises, magnetically shielded rooms (MSRs) are used for biomagnetic measurements, etc. The sources of environmental noises are far away from the MSR, in such a way that almost uniform magnetic field is applied to the MSR. To evaluate the shielding factor for the uniform magnetic field in a construction site, the magnetic noises are applied
Shunya Odawara; Kazuhiro Muramatsu; Yanhui Gao; Shogo Komori; Keita Yamazaki; Toshifumi Shinnoh; Takao Yamaguchi; Mitsuru Sakakibara; Masao Shimokawa
Dust Abatement in Shield Supports by Means of Extraction and Precipitation of the Fine Dust in the Gaps Between Shields.
National Technical Information Service (NTIS)
Shield supports are used in coal mines all over the world. The shielding of the face area is not sufficient, however, and dust will be raised especially when the shields are moved. The resulting dust loads often exceed the maximum permissible values, so t...
U. Oden
LL/ILW: Post-Qualification of Old Waste through Non-Destructive Extraction of Barrels from Cement Shields - 13535
Currently there is a large number of radioactive waste drums entombed in cement shields at German nuclear power plants. These concrete containers used in the past for the waste are not approved for the final repository. Compliance with current acceptance criteria of the final repository has to be proven by qualification measures on the waste. To meet these criteria, a new declaration and new packing is necessary. A simple non-destructive extraction of about 2000 drums from their concrete shields is not possible. So different methods were tested to find a way of non-destructive extraction of old waste drums from cement shields and therefore reduce the final repository volume and final repository costs by using a container accepted and approved for Konrad. The main objective was to build a mobile system to offer this service to nuclear plant stations. (authors)
Oehmigen, Steffen [GNS Gesellschaft fuer Nuklear-Service mbH (Germany)] [GNS Gesellschaft fuer Nuklear-Service mbH (Germany); Ambos, Frank [Sat. Kerntechnik GmbH (Germany)] [Sat. Kerntechnik GmbH (Germany)
NSDL National Science Digital Library
From the Department of Energy's Center of Excellence for Sustainable Development, this Green Buildings site serves as a detailed metapage for environmentally conscious architects, engineers, and builders. As the introduction to the site points out, "The design, construction, and maintenance of buildings has a tremendous impact on our environment and our natural resources." The site offers carefully summarized links to relevant Websites and publications on topics such as building principles, building programs, rating systems, affordable housing, codes/ordinances, educational materials, and more. This site may be of interest to those who want practical applications for protecting the environment.
NSDL National Science Digital Library
In this Bob the Builder(TM)-themed activity, learners explore what it means to work together as a team. Learners repeat the phrase �Can We Build It?(TM) Yes We Can!� until they can chant it together as a team. Then, learners repeat the chant at each activity station. Learners rotate through the stations where they build with blocks, LEGO® bricks or other small manipulatives, hammer nails and wood, pump with water, and construct a building site by moving sand with toy trucks. This activity is featured on page 9 of the "Bob the Builder(TM) � Project: Build It" unit of study.
Indianapolis, The C.
NSDL National Science Digital Library
Build a house you can fit inside, using cardboard tubes. Variations of this activity include building for a toy (easier) or building a house the right size for a stuffed animal or a garage for a toy car. Also included is an option to build houses inspired by those around the world (harder). This activity focuses on the understanding of sizes and shapes: Can I fit in this if I stand up? if I sit? Do we have enough cardboard tubes to make a triangular roof? This activity is available as a webpage and a downloadable pdf. Students should have the ability to use scissors and tape well.
Analytic Ballistic Performance Model of Whipple Shields
NASA Technical Reports Server (NTRS)
The dual-wall Whipple shield is the shield of choice for lightweight, long-duration flight. The shield uses an initial sacrificial wall to initiate fragmentation and melt an impacting threat that expands over a void before hitting a subsequent shield wall of a critical component. The key parameters to this type of shield are the rear wall and its mass which stops the debris, as well as the minimum pressure generated under threat particle impact of the sacrificial wall and the amount of void that is available for expansion. Ensuring the minimum pressure is sufficiently high to achieve large scale fragmentation/melt of the threat particle enables the expansion of the threat and reduces the momentum flux of the debris on the rear wall. Three key factors in the minimum pressure achieved are the thickness of the sacrificial wall relative to the characteristic dimension of the impacting particle, the density and material cohesion contrast of the sacrificial wall relative to the threat particle and the impact speed. The mass of the rear wall and the sacrificial wall are desirable to minimize for launch costs and dynamic concerns making it important to have an understanding of the effects of density contrast and impact speed. In this paper a fourth key parameter is identified related to fragmentation, which corresponds to the ratio of the size of the projectile relative to the transition from brittle to ductile hole growth in the projectile. Ballistic limit equations have been developed to define the failure limits of a MMOD shield, generally in terms of projectile diameter (or mass), impact velocity, and angle. Within the range of impact velocities relevant for Earth-orbiting spacecraft, three distinct regions of penetration phenomenology have been identified for Whipple shields: center dot Low velocity: the projectile is eroded (and possibly deformed) during its passage through the bumper plate, but is not fragmented. Thus, perforation of the rear wall is by a fragment with a mass and speed equal to or less than the original impactor. center dot Intermediate (shatter) velocity: impact velocities are sufficient to induce projectile fragmentation upon impact with the bumper plate, resulting in a coarse debris cloud with large solid fragments. Increasing velocity within the shatter regime results in increased fragmentation, and eventually melting, of the projectile and bumper fragments, generating a finer and more evenly dispersed debris cloud. Failure of the rear wall is a complicated combination of modes observed at low- and hypervelocity. center dot Hypervelocity: the projectile and holed-out bumper material is completely, or nearly completely, melted and/or vaporized by the initial impact. The resultant debris cloud impacts over a dispersed area of the rear wall, loading it impulsively and inducing failure through rupture or petalling. While each of these regimes are well observed with extensive empirical methods to describe these regions, differences in impactor materials, configurations of shields and questions about the limitations of the attainable impact speeds have left questions that are difficult to answer from completely empirical methods.
Miller, J. E.; Bjorkman, M. D.; Christiansen, E. L.; Ryan, S. J.
Supplemental heating of deposition tooling shields
A method of reducing particle generation from the thin coating deposited on the internal surfaces of a deposition chamber which undergoes temperature variation greater than 100.degree. C. comprising maintaining the temperature variation of the internal surfaces low enough during the process cycle to keep thermal expansion stresses between the coating and the surfaces under 500 MPa. For titanium nitride deposited on stainless steel, this means keeping temperature variations under approximately 70.degree. C. in a chamber that may be heated to over 350.degree. C. during a typical processing operation. Preferably, a supplemental heater is mounted behind the upper shield and controlled by a temperature sensitive element which provides feedback control based on the temperature of the upper shield.
Ohlhausen, James A. (Albuquerque, NM); Peebles, Diane E. (Albuquerque, NM); Hunter, John A. (Albuquerque, NM); Eckelmeyer, Kenneth H. (Albuquerque, NM)
Electronically shielded solid state charged particle detector
An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged particles when the received charged particles are applied to the active surface. A conductive layer is disposed upon the active surface. In a preferred embodiment, a nonconductive layer is disposed between the conductive layer and the active surface. The conductive layer is electrically coupled to the detector housing to provide a substantially continuous conductive electrical shield surrounding the active surface. The inner surface of the detector housing is supplemented with a radio frequency absorbing material such as ferrite.
Balmer, David K. (155 Coral Way, Broomfield, CO 80020); Haverty, Thomas W. (1173 Logan, Northglenn, CO 80233); Nordin, Carl W. (7203 W. 32nd Ave., Wheatridge, CO 80033); Tyree, William H. (1977 Senda Rocosa, Boulder, CO 80303)
Phase shielding soliton in parametrically driven systems.
Parametrically driven extended systems exhibit dissipative localized states. Analytical solutions of these states are characterized by a uniform phase and a bell-shaped modulus. Recently, a type of dissipative localized state with a nonuniform phase structure has been reported: the phase shielding solitons. Using the parametrically driven and damped nonlinear Schr�dinger equation, we investigate the main properties of this kind of solution in one and two dimensions and develop an analytical description for its structure and dynamics. Numerical simulations are consistent with our analytical results, showing good agreement. A numerical exploration conducted in an anisotropic ferromagnetic system in one and two dimensions indicates the presence of phase shielding solitons. The structure of these dissipative solitons is well described also by our analytical results. The presence of corrective higher-order terms is relevant in the description of the observed phase dynamical behavior. PMID:23767606
Clerc, Marcel G; Garcia-�ustes, M�nica A; Z�rate, Yair; Coulibaly, Saliya
Electronically shielded solid state charged particle detector
An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged particles when the received charged particles are applied to the active surface. A conductive layer is disposed upon the active surface. In a preferred embodiment, a nonconductive layer is disposed between the conductive layer and the active surface. The conductive layer is electrically coupled to the detector housing to provide a substantially continuous conductive electrical shield surrounding the active surface. The inner surface of the detector housing is supplemented with a radio frequency absorbing material such as ferrite. 1 fig.
Balmer, D.K.; Haverty, T.W.; Nordin, C.W.; Tyree, W.H.
Thermoforming plastic in lead shield construction
Radiation treatments using low energy X-rays or electrons frequently require a final field defining shield to be placed on the patient's skin. A custom made lead cut-out is used to provide a close fit to a particular patient's surface contours. We have developed a procedure which utilizes POLYFORM thermoplastic to obtain a negative mold of the patient instead of the traditional plaster bandage or dental impression gel. The Polyform is softened in warm water, molded carefully over the patient's surface, and is removed when set or hardened, usually within five minutes. Then lead sheet cut-outs can be formed within this negative. For shielding cut-outs requiring thicker lead sheet, a positive is made from dental stone using this Polyform negative. We have found this procedure to be neat, fast and comfortable for both patient and the dosimetrist.
Abrahams, M.E.; Chow, C.H.; Loyd, M.D. (Univ. of Texas Medical Branch, Galveston (USA))
Debye shielding in a nonextensive plasma
The phenomenon of Debye Shielding is revisited within the theoretical framework of the Tsallis statistical mechanics. The plasma consists of nonextensive electrons and ions. Both the effective Debye length {lambda}{sub D}{sup q} and the fall-off of the electrostatic potential {Phi} are considered and a parameter study conducted. Owing to electron nonextensivity, the critical Mach number derived from the modified Bohm sheath criterion may become less than unity allowing therefore ions with speed less than ion-acoustic speed to enter the sheath from the main body of the plasma. Considering the wide relevance of collective processes, our analysis may be viewed as a first step toward a more comprehensive Debye shielding and electrostatic plasma sheath in nonequilibrium plasmas.
Ait Gougam, Leila; Tribeche, Mouloud [Faculty of Sciences-Physics, Theoretical Physics Laboratory (TPL), University of Bab-Ezzouar, U.S.T.H.B, B.P. 32, El Alia, Algiers 16111 (Algeria)
... Stages of Adolescence Ages & Stages Listen Stages of Adolescence Article Body Adolescence, these years from puberty to adulthood, may be roughly divided into three stages: early adolescence, generally ages eleven to fourteen; middle adolescence, ages ...
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When the second stage burn is complete, the spacecraft and third stage are spun up to 55 rpm to stabilize the third stage during its short firing. The second stage is then jettisoned and the third ...
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Magnetic radiation shielding - An idea whose time has returned?
NASA Technical Reports Server (NTRS)
One solution to the problem of shielding crew from particulate radiation in space is to use active electromagnetic shielding. Practical types of shield include the magnetic shield, in which a strong magnetic field diverts charged particles from the crew region, and the magnetic/electrostatic plasma shield, in which an electrostatic field shields the crew from positively charged particles, while a magnetic field confines electrons from the space plasma to provide charge neutrality. Advances in technology include high-strength composite materials, high-temperature superconductors, numerical computational solutions to particle transport in electromagnetic fields, and a technology base for construction and operation of large superconducting magnets. These advances make electromagnetic shielding a practical alternative for near-term future missions.
Landis, Geoffrey A.
Enrichment Determination of Uranium in Shielded Configurations
The determination of the enrichment of uranium is required in many safeguards and security applications. Typical methods of determining the enrichment rely on detecting the 186 keV gamma ray emitted by {sup 235}U. In some applications, the uranium is surrounded by external shields, and removal of the shields is undesirable. In these situations, methods relying on the detection of the 186 keV gamma fail because the gamma ray is shielded easily. Oak Ridge National Laboratory (ORNL) has previously measured the enrichment of shielded uranium metal using active neutron interrogation. The method consists of measuring the time distribution of fast neutrons from induced fissions with large plastic scintillator detectors. To determine the enrichment, the measurements are compared to a calibration surface that is created from Monte Carlo simulations where the enrichment in the models is varied. In previous measurements, the geometry was always known. ORNL is extending this method to situations where the geometry and materials present are not known in advance. In the new method, the interrogating neutrons are both time and directionally tagged, and an array of small plastic scintillators measures the uncollided interrogating neutrons. Therefore, the attenuation through the item along many different paths is known. By applying image reconstruction techniques, an image of the item is created which shows the position-dependent attenuation. The image permits estimating the geometry and materials present, and these estimates are used as input for the Monte Carlo simulations. As before, simulations predict the time distribution of induced fission neutrons for different enrichments. Matching the measured time distribution to the closest prediction from the simulations provides an estimate of the enrichment. This presentation discusses the method and provides results from recent simulations that show the importance of knowing the geometry and materials from the imaging system.
Crye, Jason Michael [ORNL; Hall, Howard L [ORNL; McConchie, Seth M [ORNL; Mihalczo, John T [ORNL; Pena, Kirsten E [ORNL
SINBAD: Shielding integral benchmark archive and database
SINBAD is a new electronic database developed to store a variety of radiation shielding benchmark data so that users can easily retrieve and incorporate the data into their calculations. SINBAD is an excellent data source for users who require the quality assurance necessary in developing cross-section libraries or radiation transport codes. The future needs of the scientific community are best served by the electronic database format of SINBAD and its user-friendly interface, combined with its data accuracy and integrity.
Hunter, H.T.; Ingersoll, D.T.; Roussin, R.W. [and others
Trailing Shield For Welding On Pipes
NASA Technical Reports Server (NTRS)
Trailing shield ensures layer of inert gas covers hot, newly formed bead between two tubes or pipes joined by plasma arc welding. Inert gas protects weld bead from oxidation by air until cooler and less vulnerable to oxidation. Intended for use on nickel-base alloy pipes, on which weld beads remain hot enough to oxidize after primary inert-gas purge from welding-torch cup has passed.
Coby, John B., Jr.; Gangl, Kenneth J.
Applicability of oxide superconductor to magnetic shielding
Magnetic shielding capability has been investigated on the Y-Ba-Cu-O oxide superconductor, aiming at a practical use of oxide superconductors. Critical-transport-current density and magnetization were measured using the four-terminal and electromagnetic methods at temperatures of 77 K and 4.2 K. The results indicated that the critical-current density by the transport measurement was two orders of magnitude lower than that by the
T. Okada; K. Takahata; S. Nishijima; S. Yoshida; T. Hanasaka
Sandwich composite approach for EMI shielding structures
A sandwich composite approach has been employed to develop epoxy based polymer matrix composite materials to realize a class of lightweight structures capable of shielding electromagnetic interference (EMI). Hollow glass microspheres embedded syntactic foams (thickness ap 2 mm; density ap 0.6 g\\/cc) of two different varieties have been used as core materials in these sandwich constructions (total thickness ap 2.6
S. Dasgupta; K. Ravi Sekhart; B. N. Ravishankar; M. Kumar; S. Sankaran
Activation characteristics of concrete shields containing colemanite
NASA Astrophysics Data System (ADS)
This paper presents the theoretical results of the activation characteristics of a concrete shield containing colemanite, which is a boron-bearing mineral. Calculations are performed with a computer code, ANITA. The total activity and dose values of the sheilds with or without colemanite are compared for different continuous irradiation periods and neutron fluxes. The effect of colemanite on the activity is discussed by investigating the predominant radioisotopes at the shutdown radioactive inventory and the reactions that produce them.
Yarar, Yasemin
Spallation Neutron Source Radiation Shielding Issues
This paper summarizes results of Spallation Neutron Source calculations to estimate radiation hazards and shielding requirements for activated Mercury, target components, target cooling water, and {sup 7}Be plateout. Dose rates in the accelerator tunnel from activation of magnets and concrete were investigated. The impact of gaps and other streaming paths on the radiation environment inside the test cell during operation and after shutdown were also assessed.
Azmy, Y.Y.; Barnes, J.M.; Drischler, J.D.; Johnston, J.O.; Lillie, R.A.; McNeilly, G.S.; Santoro, R.T.
SHIELD: a comprehensive earth-protection architecture
NASA Astrophysics Data System (ADS)
The greatest natural threat to the long-term survivability of mankind is an asteroid or comet impact with the Earth. SHIELD is an architectural concept for a comprehensive Earth defense system designed to discover, catalog, calculate orbits of near-Earth objects, and to deflect potential impactors. SHIELD consists of Sentries, Soldiers, and an Earth Control Center. Sentries are spacecraft designed to search and locate NEOs of all types. Sentries maximize the lead-time for a potential impact, which simplifies the task of the Soldiers to deflect the object. Sentry spacecraft determine the orbit of each object, and compare it with the onboard database of known NEOs. The results are kept in a distributed space-Earth database. Soldier spacecraft deflect or disperse the potential impactor. Several mitigation methods have been compared by their specific impulse. Each technique requires some development to be feasible. These techniques can be categorized into "rendezvous" in which the Soldier physically lands on the NEO and "intercept". The required number of Soldiers and their locations has been examined. SHIELD has clearly shown that an Earth-protection system is practical and that a full system could be built within a few years. Indeed, very capable Sentries can be launched today.
Gold, R. E.
A new mechanism for supernova explosions called gravitational field shielding is proposed, in accord with a five-dimensional fully covariant Kaluza-Klein theory with a scalar field that unifies the four-dimensional Einsteinian general relativity and Maxwellian electromagnetic theory. It is shown that a dense compact collapsing core of a star will suddenly turn off or completely shield its gravitational field when the core collapses to a critical density, which is inversely proportional to the square of mass of the core. As the core suddenly turns off its gravity, the extremely large pressure immediately stops the core collapse and pushes the mantle material of supernova moving outward. The work done by the pressure in the expansion can be the order of energy released in a supernova explosion. The gravity will resume and stop the core from a further expansion when the core density becomes less than the critical density. Therefore, the gravitational field shielding leads a supernova to impulsively explode and form a compact object such as a neutron star as a remnant. It works such that a compressed spring will shoot the oscillator out when the compressed force is suddenly removed.
Zhang, T. X. [Physics Department, Alabama A and M University, Normal, AL 35762 (United States)
Probabilistic Estimate of Seismic Damage to the Waste-Handling Building of a Repository Located at Yucca Mountain, Nevada.
National Technical Information Service (NTIS)
The waste-handling building (WHB) at the Yucca Mountain repository is a reinforced concrete structure with massive shear walls whose thicknesses are established by shielding requirements. The probabilities of seismic damage to the WHB are calculated in th...
O. K. Kiciman N. A. Abrahamson
Shielding analysis and design of the KIPT experimental neutron source facility of Ukraine.
Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of an experimental neutron source facility based on the use of an electron accelerator driven subcritical (ADS) facility [1]. The facility uses the existing electron accelerators of KIPT in Ukraine. The neutron source of the sub-critical assembly is generated from the interaction of 100 KW electron beam with a natural uranium target. The electron beam has a uniform spatial distribution and the electron energy in the range of 100 to 200 MeV, [2]. The main functions of the facility are the production of medical isotopes and the support of the Ukraine nuclear power industry. Reactor physics experiments and material performance characterization will also be carried out. The subcritical assembly is driven by neutrons generated by the electron beam interactions with the target material. A fraction of these neutrons has an energy above 50 MeV generated through the photo nuclear interactions. This neutron fraction is very small and it has an insignificant contribution to the subcritical assembly performance. However, these high energy neutrons are difficult to shield and they can be slowed down only through the inelastic scattering with heavy isotopes. Therefore the shielding design of this facility is more challenging relative to fission reactors. To attenuate these high energy neutrons, heavy metals (tungsten, iron, etc.) should be used. To reduce the construction cost, heavy concrete with 4.8 g/cm{sup 3} density is selected as a shielding material. The iron weight fraction in this concrete is about 0.6. The shape and thickness of the heavy concrete shield are defined to reduce the biological dose equivalent outside the shield to an acceptable level during operation. At the same time, special attention was give to reduce the total shield mass to reduce the construction cost. The shield design is configured to maintain the biological dose equivalent during operation {le} 0.5 mrem/h inside the subcritical hall, which is five times less than the allowable dose for working forty hours per week for 50 weeks per year. This study analyzed and designed the thickness and the shape of the radial and top shields of the neutron source based on the biological dose equivalent requirements inside the subcritical hall during operation. The Monte Carlo code MCNPX is selected because of its capabilities for transporting electrons, photons, and neutrons. Mesh based weight windows variance reduction technique is utilized to estimate the biological dose outside the shield with good statistics. A significant effort dedicated to the accurate prediction of the biological dose equivalent outside the shield boundary as a function of the shield thickness without geometrical approximations or material homogenization. The building wall was designed with ordinary concrete to reduce the biological dose equivalent to the public with a safety factor in the range of 5 to 20.
Zhong, Z.; Gohar, M. Y. A.; Naberezhnev, D.; Duo, J.; Nuclear Engineering Division
1. Northeast face of missile site control building, commonly known ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
1. Northeast face of missile site control building, commonly known as the missile site radar building, showing open blast door #BD2. This emergency escape, at stair no. 12, is NEMP/RFI-shielded and 16" thick. The large circle in the center is the radar face, also known as the antennae array aperture. The small circle to the right of the radar face is the "Q" channel. The antennae atop the turret provided lightning protection for the building - Stanley R. Mickelsen Safeguard Complex, Missile Site Control Building, Northeast of Tactical Road; southeast of Tactical Road South, Nekoma, Cavalier County, ND
ITER (International Thermonuclear Experimental Reactor) reactor building design study
The International Thermonuclear Experimental Reactor (ITER) is at the midpoint of a two-year conceptual design. The ITER reactor building is a reinforced concrete structure that houses the tokamak and associated equipment and systems and forms a barrier between the tokamak and the external environment. It provides radiation shielding and controls the release of radioactive materials to the environment during both routine operations and accidents. The building protects the tokamak from external events, such as earthquakes or aircraft strikes. The reactor building requirements have been developed from the component designs and the preliminary safety analysis. The equipment requirements, tritium confinement, and biological shielding have been studied. The building design in progress requires continuous iteraction with the component and system designs and with the safety analysis. 8 figs.
Thomson, S.L.; Blevins, J.D.; Delisle, M.W. (Oak Ridge National Lab., TN (USA); Canadian Fusion Fuels Technology Project, Mississauga, ON (Canada))
NSDL National Science Digital Library
There's a great deal of talk about "building green" in the architecture and design world, but to many, this phrase may not mean a great deal. This website, created by the Building Green company, can help the uninitiated learn more about this subject. First-time visitors should click on the "Green Building Information" area. Here they can get answers to such question as "What is green?" and also learn more about green design strategies and the LEED rating system. Right next to this section is the "Case Studies" area, which features green building projects like elementary schools, commercial facilities, and university buildings. The site is rounded out by a "News" area and a detailed bibliography of websites, print resources, and so on.
Kinetics of stage ordering and stage transitions
NASA Astrophysics Data System (ADS)
A model of intercalation is presented which can be used for sophisticated three-dimensional computer simulations of staging kinetics. A realistic microscopic description of the intercalation process and of the stage-3 to stage-2 transition has been obtained for the first time. Stage disorder and three-dimensional effects are shown to be key ingredients of these phenomena. This work makes possible the first critical appraisal of the Daumass-Herold model, which is shown to be valid for uniformly intercalated high- and low-stage crystals, and to provide a useful language for describing the stage transition.
Kirczenow, G.
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
5. VIEW OF INTERIOR OF BUILDING 220, DECORATIVE FLOOR AT ENTRANCE. VINYL TILE INLAID FLOOR WITH A RED BACKGROUND, GREEN EMBLEM, BROWN AND WHITE EAGLE, RED AND WHITE SHIELD, BLACK ANCHOR, RED ARROWS AND LETTERING. - U.S. Naval Base, Pearl Harbor, Brig, Neville Way near Ninth Street at Marine Barracks, Pearl City, Honolulu County, HI
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
HOT CELL BUILDING, TRA-632. FIRST FLOOR PLAN. PLOT PLAN SHOWS RELATIONSHIP TO PLUG STORAGE BUILDING. ONE HOT CELL ENCLOSED IN CONCRETE SHIELDING. IDAHO OPERATIONS OFFICE MTR-632-IDO-1, 11/1952. INL INDEX NO. 531-0632-00-396-110560, REV. 2. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
PROCESS WATER BUILDING, TRA-605. FORMS AR SET TO CREATE THREE SHIELDED CELLS FOR THE PUMPS THAT WILL BE IN WEST HALF OF THE BUILDING. PUMPS WILL LIFT WATER TO WORKING RESERVOIR. CAMERA FACES NORTHEAST. INL NEGATIVE NO. 1465. Unknown Photographer, 2/13/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID
LOFT. West side of containment building and dome (TAN650). Camera ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
LOFT. West side of containment building and dome (TAN-650). Camera is atop earth -shield control building (TAN-630), facing east. Vertical structure at right of view (with light affixed) is west end of railroad door shroud. Date: May 2004. INEEL negative no. HD-39-19-1 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
Radiation shielding for future space exploration missions
NASA Astrophysics Data System (ADS)
Scope and Method of Study. The risk to space crew health and safety posed by exposure to space radiation is regarded as a significant obstacle to future human space exploration. To countermand this risk, engineers and designers in today's aerospace community will require detailed knowledge of a broad range of possible materials suitable for the construction of future spacecraft or planetary surface habitats that provide adequate protection from a harmful space radiation environment. This knowledge base can be supplied by developing an experimental method that provides quantitative information about a candidate material's space radiation shielding efficacy with the understanding that (1) shielding is currently the only practical countermeasure to mitigate the effects of space radiation on human interplanetary missions, (2) any mass of a spacecraft or planetary surface habitat necessarily alters the incident flux of ionizing radiation on it, and (3) the delivery of mass into LEO and beyond is expensive and therefore may benefit from the possible use of novel multifunctional materials that could in principle reduce cost as well as ionizing radiation exposure. The developed method has an experimental component using CR-39 PNTD and Al2O3:C OSLD that exposes candidate space radiation shielding materials of varying composition and depth to a representative sample of the GCR spectrum that includes 1 GeV 1H and 1 GeV/n 16O, 28Si, and 56Fe heavy ion beams at the BNL NSRL. The computer modeling component of the method used the Monte Carlo radiation transport code FLUKA to account for secondary neutrons that were not easily measured in the laboratory. Findings and Conclusions. This study developed a method that quantifies the efficacy of a candidate space radiation shielding material relative to the standard of polyethylene using a combination of experimental and computer modeling techniques. The study used established radiation dosimetry techniques to present an empirical weighted figure of merit (WFoM) approach that quantifies the effectiveness of a candidate material to shield space crews from the whole of the space radiation environment. The results of the WFoM approach should prove useful to designers and engineers in seeking alternative materials suitable for the construction of spacecraft or planetary surface habitats needed for long-term space exploration missions. The dosimetric measurements in this study have confirmed the principle of good space radiation shielding design by showing that low-Z� materials are most effective at reducing absorbed dose and dose equivalent while high-Z� materials are to be avoided. The relatively high WFoMs of carbon composite and lunar- and Martian-regolith composite could have important implications for the design and construction of future spacecraft or planetary surface habitats. The ground-based measurements conducted in this study have validated the heavy ion extension of FLUKA by producing normalized differential LET fluence spectra that are in good agreement with experiment.
DeWitt, Joel Michael
Safety evaluation for packaging (onsite) for the concrete-shielded RH TRU drum for the 327 Postirradiation Testing Laboratory
This safety evaluation for packaging authorizes onsite transport of Type B quantities of radioactive material in the Concrete Shielded Remote-Handled Transuranic Waste (RH TRU) Drum per HNF-PRO-154, Responsibilities and Procedures for all Hazardous Material Shipments. The drum will be used for transport of 327 Building legacy waste from the 300 Area to a solid waste storage facility on the Hanford Site.
Smith, R.J.
Reduction of Lightning-Induced Magnetic Fields and Voltages Inside Struck Double-Layer Grid-Like Shields
This paper presents a numerical analysis of the reduction of lightning-induced magnetic fields and voltages inside double-layer grid-like spatial shields typically used in reinforced concrete buildings, e.g., nuclear power plants. The calculations are performed with the CONCEPT computer code, which solves Maxwell's equations using the method of moments in the frequency domain. The computer code is extended with the well-known
Ibrahim A. Metwally; Fridolin H. Heidler
Design and engineering of a large shielded semi-anechoic chamber meeting the volumetric NSA requirements at 3 and 10 m transmission length
A large shielded semianechoic chamber meeting the validation requirements for alternative test sites as specified in ANSI C63.4-1991 (and equivalent CISPR and EN drafts) has been realized at the CESI EMC Laboratory, Milan, Italy. The authors discuss the problems of integration in a preexisting building of the semianechoic performance with all the hardware that makes the site practically useable, such
B. Audone; L. Bolla; G. Costa; A. Manara; H. Pues
Preventing Accidental Ignition of Upper-Stage Rocket Motors
NASA Technical Reports Server (NTRS)
A report presents a proposal to reduce the risk of accidental ignition of certain upper-stage rocket motors or other high energy hazardous systems. At present, mechanically in-line initiators are used for initiation of many rocket motors and/or other high-energy hazardous systems. Electrical shorts and/or mechanical barriers, which are the basic safety devices in such systems, are typically removed as part of final arming or pad preparations while personnel are present. At this time, static discharge, test equipment malfunction, or incorrect arming techniques can cause premature firing. The proposal calls for a modular out-of-line ignition system incorporating detonating-cord elements, identified as the donor and the acceptor, separated by an air gap. In the safe configuration, the gap would be sealed with two shields, which would prevent an accidental firing of the donor from igniting the system. The shields would be removed to enable normal firing, in which shrapnel generated by the donor would reliably ignite the acceptor to continue the ordnance train. The acceptor would then ignite a through bulkhead initiator (or other similar device), which would ignite the motor or high-energy system. One shield would be remotely operated and would be moved to the armed position when a launch was imminent or conversely returned to the safe position if the launch were postponed. In the event of failure of the remotely operated shield, the other shield could be inserted manually to safe the system.
Hickman, John; Morgan, Herbert; Cooper, Michael; Murbach, Marcus
NSDL National Science Digital Library
In this interactive application young children become familiar with 3-dimensional shapes by matching a variety of shapes in order to build a sandcastle. There are two levels of play, parent pointers, and hints to help out along the way.
... National Center Homepage Hearing Loss Share Compartir Building Languages How can I start communicating with my baby ... English (MCE), Natural Gestures, Speech (Lip) Reading, Speech "Language" When most people hear the word "language" they ...
This book is covered under the following headings: Healthy building strategies/productivity, Energy and design issues, Ventilation, Contaminants, Thermal, airflow, and humidity issues, School-related issues, Sources and sinks, Filtering, Operation and maintenance.
Not Available
Cross Section Evaluation Group shielding benchmark compilation. Volume II
At the time of the release of ENDF/B-IV in 1974, the Shielding Subcommittee had identified a series of 12 shielding data testing benchmarks (the SDT series). Most were used in the ENDF/B-IV data testing effort. A new concept and series was begun in the interim, the so-called Shielding Benchmark (SB) series. An effort was made to upgrade the SDT series as far as possible and to add new SB benchmarks. In order to be designated in the SB class, both an experiment and analysis must have been performed. The current recommended benchmark for Shielding Data Testing are listed. Until recently, the philosophy has been to include only citations to published references for shielding benchmarks. It is now our intention to provide adequate information in this volume for proper analysis of any new benchmarks added to the collection. These compilations appear in Section II, with the SB5 Fusion Reactor Shielding Benchmark as the first entry.
Rose, P.F.; Roussin, R.W.
The Spallation Neutron Source (SNS) conceptual design shielding analysis
The shielding design is important for the construction of an intense high-energy accelerator facility like the proposed Spallation Neutron Source (SNS) due to its impact on conventional facility design, maintenance operations, and since the cost for the radiation shielding shares a considerable part of the total facility costs. A calculational strategy utilizing coupled high energy Monte Carlo calculations and multi-dimensional discrete ordinates calculations, along with semi-empirical calculations, was implemented to perform the conceptual design shielding assessment of the proposed SNS. Biological shields have been designed and assessed for the proton beam transport system and associated beam dumps, the target station, and the target service cell and general remote maintenance cell. Shielding requirements have been assessed with respect to weight, space, and dose-rate constraints for operating, shutdown, and accident conditions. A discussion of the proposed facility design, conceptual design shielding requirements calculational strategy, source terms, preliminary results and conclusions, and recommendations for additional analyses are presented.
Johnson, J.O.; Odano, N.; Lillie, R.A.
Shielding Design of the Spallation Neutron Source (SNS)
The shielding design is important for the construction of an intense high-energy accelerator facility like the proposed Spallation Neutron Source (SNS) due to its impact on conventional facility design, maintenance operations, and since the cost for the radiation shielding shares a considerable part of the total facility costs. A calculational strategy utilizing coupled high energy Monte Carlo calculations and multi-dimensional discrete ordinates calculations, along with semi-empirical calculations, was implemented to perform the conceptual design shielding assessment of the proposed SNS. Biological shields have been designed and assessed for the proton beam transport system and associated beam dumps, the target station, and the target service cell and general remote maintenance cell. Shielding requirements have been assessed with respect to weight, space, and dose-rate constraints for operating, shutdown, and accident conditions. A discussion of the proposed facility design, conceptual design shielding requirements, calculational strategy, source terms, preliminary results and conclusions, and recommendations for additional analyses are presented.
Johnson, J.O.
Structural Monitoring of Metro Infrastructure during Shield Tunneling Construction
Shield tunneling construction of metro infrastructure will continuously disturb the soils. The ground surface will be subjected to uplift or subsidence due to the deep excavation and the extrusion and consolidation of the soils. Implementation of the simultaneous monitoring with the shield tunnel construction will provide an effective reference in controlling the shield driving, while how to design and implement a safe, economic, and effective structural monitoring system for metro infrastructure is of great importance and necessity. This paper presents the general architecture of the shield construction of metro tunnels as well as the procedure of the artificial ground freezing construction of the metro-tunnel cross-passages. The design principles for metro infrastructure monitoring of the shield tunnel intervals in the Hangzhou Metro Line 1 are introduced. The detailed monitoring items and the specified alarming indices for construction monitoring of the shield tunneling are addressed, and the measured settlement variations at different monitoring locations are also presented.
Ran, L.; Ye, X. W.; Ming, G.; Dong, X. B.
Early shielding research at Bettis Atomic Power Laboratory
Reminiscences of shielding research at Bettis Atomic Power Laboratory (BAPL) always have in the background the reason for its existence - the design of efficient and safe reactors. Shielding is essential for personnel safety. However, the only computational tools available in the early 1950s were slide rules and desk calculators. Under these conditions, any shield desing calculation accurate within a factor of 2 was a good one, and the phrases close enough for shielding purposes' and including a factor for conservation' became a permanent part of the shielding vocabulary. This early work instilled a respect for hand calculations and the requirements that nay result, no matter how calculated, must meet the test of being reasonable and in line with previous experience. Even today, with sophisticated shielding programs available on the latest computers, calculated results must pass the same test.
Shure, K.; Wallace, O.J. (Westinghouse Electric Corp., West Mifflin, PA (United States))
A thermal shield concept for the Solar Probe mission
NASA Technical Reports Server (NTRS)
The Solar Probe spacecraft will travel to within 4 solar radii of the sun's center while performing a variety of fundamental experiments in space physics. Exposure to 2900 earth suns (400 W/sq cm) at perihelion imposes severe thermal and material demands on a solar shield system designed to protect the payload that will reside within the shield's shadow envelope or umbra. The design of the shield subsystem is a thermal/materials challenge requiring new technology development. While currently in the preproject study phase, anticipating a 1995 project start, shield preliminary design efforts are currently underway. This paper documents the current status of the mission concept, the materials issues, the configuration concept for the shield subsystem, the current configuration studies performed to date, and the required material testing to provide a database to support a design effort required to develop the shield subsystem.
Miyake, Robert N.; Millard, Jerry M.; Randolph, James E.
X-ray transmissive debris shield
An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.
Spielman, Rick B. (Albuquerque, NM) [Albuquerque, NM
X-ray transmissive debris shield
An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.
Spielman, R.B.
Shielded serpentine traveling wave tube deflection structure
A shielded serpentine slow wave deflection structure (10) having a serpene signal conductor (12) within a channel groove (46). The channel groove (46) is formed by a serpentine channel (20) in a trough plate (18) and a ground plane (14). The serpentine signal conductor (12) is supported at its ends by coaxial feed through connectors 28. A beam interaction trough (22) intersects the channel groove (46) to form a plurality of beam interaction regions (56) wherein an electron beam (54) may be deflected relative to the serpentine signal conductor (12).
Hudson, Charles L. (Santa Barbara, CA); Spector, Jerome (Berkeley, CA)
Equivalent-spherical-shield neutron dose calculations
Neutron doses through 162-cm-thick spherical shields were calculated to be 1090 and 448 mrem/h for regular and magnetite concrete, respectively. These results bracket the measured data, for reinforced regular concrete, of /approximately/600 mrem/h. The calculated fraction of the high-energy (>20 MeV) dose component also bracketed the experimental data. The measured and calculated doses were for a graphite beam stop bombarded with 100 nA of 800-MeV protons. 6 refs., 2 figs., 1 tab.
Russell, G.J.; Robinson, H.
SHIELD: Stellar Mass Estimates from Spitzer Imaging
NASA Astrophysics Data System (ADS)
The Survey of HI in Extremely Low-mass Dwarfs (SHIELD) is an ongoing study of twelve galaxies with HI masses between 106 and 107 Solar masses, detected by the Arecibo Legacy Fast ALFA (ALFALFA) survey. The distribution of stellar mass in each system is a crucial component of our understanding of the baryonic and dark matter contents of these galaxies. Using Spitzer Space Telescope 3.6 and 4.5 micron imaging, we have measured the flux of each galaxy. In conjunction with distances derived from Hubble Space Telescope imaging, we have determined the stellar mass and its distribution as a function of radius for ten of the twelve systems.
Cannon, John M.; Marshall, M.; Cave, I.; Larson, E.; Moody, S.; Adams, E. A.; Dolphin, A. E.; Elson, E. C.; Giovanelli, R.; Haynes, M. P.; McQuinn, K. B.; Ott, J.; Saintonge, A.; Salzer, J. J.; Skillman, E. D.
Formulas Giving Buildup Factor for Double-Layered Shields
Formulas that give absorbed dose buildup factors for two-layered shields have been developed based on gamma-ray absorption buildup factors computed with the Monte Carlo Neutral Particle Transport Code System (MCNP). The shielding materials considered were water, lead, steel, concrete, and some of their combinations for two-layered shields with thicknesses between 1 to 10 mfp. Gamma energy considered ranged from 0.5
Mevlut Guvendik; Nicholas Tsoulfanidis
An Improved Model of Loads Acting on Shield
Shield tunneling technologies have been developed for constructing tunnels in soft ground especially with groundwater. However,\\u000a the automatic deviation correction systems are based on empirical relationships or theoretical model including a great deal\\u000a of unknown parameters. In this paper, the shield-segment system is considered as underground parallel manipulators, so the\\u000a shield behavior can be represented by the rotation of motion
Xiangtao Hu; Zhouping Yin; Yongan Huang
Fast neutron shielding and neutron transport studies at YAYOI
The fast neutron shielding experiments at the fast neutron source reactor YAYOI of the University of Tokyo were summarized. The experiments were grouped into the following four types; 1.(1)|experiments for shield design of fast breeder reactor,2.(2)|fast neutron transmission experiments,3.(3)|fast neutron streaming experiments,4.(4)|neutron skyshine experiment. The experimental data are useful for shield design and assessing the accuracy of the calculational methods.The
Y. Oka; K. Furuta; S. An
Polyethylene/Boron Composites for Radiation Shielding Applications
Multifunctional composites made with boron are absorbers of low energy nuetrons, and could be used for structural shielding materials. Polyethylene/boron carbide composites were fabricated using conventional polymer processing techniques, and were evaluated for mechanical and radiation shielding properties. Addition of neat boron carbide (powder and nanoparticles) to an injection molding grade HPDE showed superior mechanical properties compared to neat HDPE. Radiation shielding measurements of a 2 wt% boron carbide composite were improved over those of the neat polyethylene.
Harrison, Courtney; Grulke, Eric [Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506 (United States); Burgett, Eric; Hertel, Nolan [Neely Nuclear Research Center, Georgia Institute of Technology, Atlanta, GA 30332 (United States)
31P NMR chemical shielding tensor of 2-aminoethylphosphonic acid
The symmetric part of the 31P NMR chemical shielding tensor was determined in a single crystal of 2-aminoethylphosphonic acid (AEP). The principal values, relative to 85% H3PO4, are ?11=87.1, ?22=15.6, and ?33=?47.5 ppm. Four orientations of the chemical shielding tensor on the molecule are possible, but only one of them shows correlation with the bond directions. The two most shielded
Marie-Rose Van Calsteren; George I. Birnbaum; Ian C. P. Smith
BrowserShield: Vulnerability-driven filtering of dynamic HTML
Abstract Vulnerability-driven filtering of network data can offer a fast and easy-to-deploy alternative or intermediary to software patching, as exemplified in Shield [43]. In this paper, we take Shield�s vision to a new domain, inspect- ing and cleansing not just static content, but also dy- namic,content. The dynamic,content we target is the dynamic HTML in web pages, which have become
Charles Reis; John Dunagan; Helen J. Wang; Opher Dubrovsky; Saher Esmeir
Major uncertainties influencing entry probe heat shield design
NASA Technical Reports Server (NTRS)
Factors influencing the design of an outer planet probe heat shield are discussed. Major factors included are: uncertainties in composition and scale height of the planet atmospheres; the augmentation/attenuation of entry heating by ablation products requires more computer study and testing; carbon heat shields, especially carbon phenolic, possessing improved resistance to spallation need developing; and white silica reflecting heat shields with improved resistance to bulk vitrification need further developing.
Congdon, W.
Hypervelocity impact simulation for micrometeorite and debris shield design
NASA Technical Reports Server (NTRS)
A new capability has been developed for direct computer simulation of hypervelocity impacts on multi-plate orbital debris shields, for combinations of low shield thickness and wide shield spacing which place extreme demands on conventional Eulerian analysis techniques. The modeling methodology represents a novel approach to debris cloud dynamics simulation, a problem of long term interest in the design of space structures. Software implementation of the modeling methodology provides a new design tool for engineering analysis of proposed orbital debris protection systems.
Fahrenthold, Eric P.
The differing shieldmg requirements of a fast breeder reactor and a ; thermal reactor are discussed. The functions of a stainless steel layer inside ; the reactor vessel of a fast breeder are outlined: neutron reflector, gamma-ray ; absorbing thermal shield, and an inelastic neutron scatterer to protect the ; vessel walls against radiation damage. The use of borated graphite