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Office of Scientific and Technical Information
Porous fission fragment tracks in fluorapatite
Science Conference Proceedings (OSTI)
Fission tracks caused by the spontaneous fission of {sup 238}U in minerals, as revealed by chemical etching, are extensively used to determine the age and thermal history of Earth's crust. Details of the structure and annealing of tracks at the atomic scale have remained elusive, as the original track is destroyed during chemical etching. By combining transmission electron microscopy with in situ heating, we demonstrate that fission tracks in fluorapatite are actually porous tubes, instead of having an amorphous core, as generally assumed. Direct observation shows thermally induced track fragmentation in fluoapatite, in clear contrast to the amorphous tracks in zircon, which gradually ''fade'' without fragmentation. Rayleigh instability and the thermal emission of vacancies control the annealing of porous fission tracks in fluorapatite.
Li Weixing; Ewing, Rodney C. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1005 (United States); Wang Lumin [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Sun Kai [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Lang, Maik [Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109-1005 (United States); Trautmann, Christina [GSI Helmholtz Centre for Heavy Ion Research, Planckstr. 1, 64291 Darmstadt (Germany)
Dating thermal events at Cerro Prieto using fission track annealing
DOE Green Energy (OSTI)
Data from laboratory experiments and geologic fading studies were compiled from published sources to produce lines of iso-annealing for apatite in time-temperature space. Fission track ages were calculated for samples from two wells at Cerro Prieto, one with an apparently simple and one with an apparently complex thermal history. Temperatures were estimated by empirical vitrinite reflectance geothermometry, fluid inclusion homogenization and oxygen isotope equilibrium. These estimates were compared with logs of measured borehole temperatures.
Sanford, S.J.; Elders, W..
Predicting nucleosome positioning using multiple evidence tracks
We describe a probabilistic model, implemented as a dynamic Bayesian network, that can be used to predict nucleosome positioning along a chromosome based on one or more genomic input tracks containing position-specific information (evidence) Previous ... Keywords: chromatin structure, dynamic bayesian network, nucleosome prediction
Sheila M. Reynolds; Zhiping Weng; Jeff A. Bilmes; William Stafford Noble
Implications of fission-track annealing for geothermal models in the Pacific Northwest. Technical progress report
A fission-track dating lab has been set up. Samples have been obtained from fossil and active geothermal systems and are in the process of being separated, counted and dated with subsequent modeling planned. The thermal model of horizontal flow in a geothermal aquifer is being prepared. Modeling of magma systems and regional thermal evolution has been confined to studies of the Rio Grande Rift and the deep holes at the Fenton Hill Dry Hot Rock locality at the edge of the Valles caldera. Samples have been obtained from one deep hole in a sedimentary basin, the western Snake River basin in eastern Oregon. These samples are being separated so that the fission-track annealing can be studied. Studies of the systematics of fission-track fading are in progress. Several models have been investigated to explain the existing fission-track fading data, and several annealing experiments are planned. The use of transmission electron microscopy (TEM) for direct observation of fission-track fading has been investigated. (LEW)
Blackwell, D.D.; Duncan, I.J.
Implications of fission track annealing for geothermal models in the Pacific Northwest
The objectives were to develop and set up a fission track annealing/dating laboratory, to apply the results of data obtained in this laboratory to a variety of geological problems associated with geothermal systems (both regional and local) and to a lesser extent sedimentary basins, and to develop a model for the thermal effects of lateral fluid flow in geothermal systems and to combine the results from the fission track studies with the results from the analytical model. The combined results could be used to constrain the flow conditions using both measured temperature data and annealing data from apatite and zircon. 14 refs., 2 figs.
Blackwell, D.D.; Duncan, I.J.; Kelley, S.
Dating thermal events at Cerro Prieto using fission-track annealing
The duration of heating in the Cerro Prieto reservoir was estimated by relating the fading of spontaneous fission tracks in detrital apatite to observed temperatures. The rate of fading is a function of both time and temperature. The apparent fission track age of the detrital apatites then, is a function of both their source age and their time-temperature history. Data from laboratory experiments and geologic fading studies were compiled from published sources to produce lines of iso-annealing for apatite in time-temperature space. Fission track ages were calculated for samples from two wells at Cerro Prieto, one with an apparently simple and one with an apparently complex thermal history. Temperatures were estimated by empirical vitrinite reflectance geothermometry, fluid inclusion homogenization and oxygen isotope equilibrium. These estimates were compared with logs of measured borehole temperatures. The temperature in well T-366, where complete annealing first occurs, was estimated to be between 160 and 180{sup 0}C. Complete annealing at these temperatures requires 10{sup 4} and 10{sup 3} years, respectively. Well M-94 has an apparently complex thermal history. Geothermometers in this well indicate temperatures some 50 to 100{sup 0}C higher than those measured directly in the borehole. Fission tracks are partially preserved in M-94 where paleotemperatures were as high as 200{sup 0}C and are erased where geothermometers indicate temperatures of 250{sup 0}C. This implies a thermal event less than 10{sup 1} years and greater than 10{sup 0} years in duration.
Sanford, S.J.; Elders, W.A.
Improved zircon fission-track annealing model based on reevaluation of annealing data
The thermal recovery (annealing) of mineral structure modified by the passage of fission fragments has long been studied by the etching technique. In minerals like apatite and zircon, the annealing kinetics are fairly well constrained from the hour to the million-year timescale and have been described by empirical and semi-empirical equations. On the other hand, laboratory experiments, in which ion beams interact with minerals and synthetic ceramics, have shown that there is a threshold temperature beyond which thermal recovery impedes ion-induced amorphization. In this work, it is assumed that this behavior can be extended to the annealing of fission tracks in minerals. It is proposed that there is a threshold temperature, T0, beyond which fission tracks are erased within a time t0, which is independent of the current state of lattice deformation. This implies that iso-annealing curves should converge to a fanning point in the Arrhenius pseudo-space (ln t vs. 1/T). Based on the proposed hypothesis, and laboratory and geological data, annealing equations are reevaluated. The geological timescale estimations of a model arising from this study are discussed through the calculation of partial annealing zone and closure temperature, and comparison with geological sample constraints found in literature. It is shown that the predictions given by this model are closer to field data on closure temperature and partial annealing zone than predictions given by previous models.
Guedes, Sandro [Instituto de Fisica Gleb Wataghin, Unicamp, Brazil; Moreira, Pedro A.F.P. [Universidade Estadual de Campinas, Sao Paulo; Devanathan, Ram [Pacific Northwest National Laboratory (PNNL); Weber, William J [ORNL; Hadler, Julio C [Instituto de Fisica Gleb Wataghin, Unicamp, Brazil
Terracentric Nuclear Fission Reactor: Background, Basis, Feasibility, Structure, Evidence, and Geophysical Implications
E-Print Network (OSTI)
The background, basis, feasibility, structure, evidence, and geophysical implications of a naturally occurring Terracentric nuclear fission georeactor are reviewed. For a nuclear fission reactor to exist at the center of the Earth, all of the following conditions must be met: (1) There must originally have been a substantial quantity of uranium within Earth's core; (2) There must be a natural mechanism for concentrating the uranium; (3) The isotopic composition of the uranium at the onset of fission must be appropriate to sustain a nuclear fission chain reaction; (4) The reactor must be able to breed a sufficient quantity of fissile nuclides to permit operation over the lifetime of Earth to the present; (5) There must be a natural mechanism for the removal of fission products; (6) There must be a natural mechanism for removing heat from the reactor; (7) There must be a natural mechanism to regulate reactor power level, and; (8) The location of the reactor or must be such as to provide containment and prevent meltdown. Herndon's georeactor alone is shown to meet those conditions. Georeactor existence evidence based upon helium measurements and upon antineutrino measurements is described. Geophysical implications discussed include georeactor origin of the geomagnetic field, geomagnetic reversals from intense solar outbursts and severe Earth trauma, as well as georeactor heat contributions to global dynamics.
J. Marvin Herndon
Theory of evidence for face detection and tracking
This paper deals with face detection and tracking by computer vision for multimedia applications. Contrary to current techniques that are based on huge learning databases and complex algorithms to get generic face models (e.g., active appearance models), ... Keywords: Cautious rule, Computer vision, Face tracking, LUX colour space, Particle filter, Transferable belief model
Francis Faux; Franck Luthon
Laboratory-Scale Bismuth Phosphate Extraction Process Simulation To Track Fate of Fission Products
SciTech Connect
Recent field investigation that collected and characterized vadose zone sediments from beneath inactive liquid disposal facilities at the Hanford 200 Areas show lower than expected concentrations of a long-term risk driver, Tc-99. Therefore laboratory studies were performed to re-create one of the three processes that were used to separate the plutonium from spent fuel and that created most of the wastes disposed or currently stored in tanks at Hanford. The laboratory simulations were used to compare with current estimates based mainly on flow sheet estimates and spotty historical data. Three simulations of the bismuth phosphate precipitation process show that less that 1% of the Tc-99, Cs-135/137, Sr-90, I-129 carry down with the Pu product and thus these isotopes should have remained within the metals waste streams that after neutralization were sent to single shell tanks. Conversely, these isotopes should not be expected to be found in the first and subsequent cycle waste streams that went to cribs. Measurable quantities (~20 to 30%) of the lanthanides, yttrium, and trivalent actinides (Am and Cm) do precipitate with the Pu product, which is higher than the 10% estimate made for current inventory projections. Surprisingly, Se (added as selenate form) also shows about 10% association with the Pu/bismuth phosphate solids. We speculate that the incorporation of some Se into the bismuth phosphate precipitate is caused by selenate substitution into crystal lattice sites for the phosphate. The bulk of the U daughter product Th-234 and Np-237 daughter product Pa-233 also associate with the solids. We suspect that the Pa daughter products of U (Pa-234 and Pa-231) would also co-precipitate with the bismuth phosphate induced solids. No more than 1 % of the Sr-90 and Sb-125 should carry down with the Pu product that ultimately was purified. Thus the current scheme used to estimate where fission products end up being disposed overestimates by one order of magnitude the partitioning Sr-90, Cs-137, and Sb-125 and by at least two orders of magnitude the portioning of Tc-99 to the first and subsequent cycle waste streams that went to cribs. Conversely, the current scheme underestimates the lanthanide and yttrium fission product quantities that went to cribs by a factor of about 3.
Serne, R. JEFFREY; Lindberg, Michael J.; Jones, Thomas E.; Schaef, Herbert T.; Krupka, Kenneth M.
Experimental evidence for the separability of compound-nucleus and fragment properties in fission
The large body of experimental data on nuclear fission is analyzed with a semi-empirical ordering scheme based on the macro-microscopic approach and the separability of compound-nucleus and fragment properties on the fission path. We apply the statistical model to the non-equilibrium descent from saddle to scission, taking the influence of dynamics into account by an early freeze out. The present approach reveals a large portion of common features behind the variety of the complex observations made for the different systems. General implications for out-of-equilibrium processes are mentioned.
Karl-Heinz Schmidt; Aleksandra Kelic; Maria Valentina Ricciardi
Evidence of microscopic effects in fragment mass distribution in heavy ion induced fusion-fission reactions
Our measurements of variances ($\\sigma_{m}^2$) in mass distributions of fission fragments from fusion-fission reactions of light projectiles (C, O and F) on deformed thorium targets exhibit a sharp anomalous increase with energy near the Coulomb barrier, in contrast to the smooth variation of $\\sigma_{m}^2$ for the spherical bismuth target. This departure from expectation based on a statistical description is explained in terms of microscopic effects arising from the orientational dependence in the case of deformed thorium targets.
T. K. Ghosh; S. Pal; K. S. Gold; P. Bhattacharya
Multimodel Approach Based on Evidence Theory for Forecasting Tropical Cyclone Tracks
In this paper a new multimodel approach for forecasting tropical cyclone tracks is presented. The approach is based on the Dempster–Shafer theory of evidence. At each forecast period, the multimodel forecast is given as an area where the tropical ...
Svetlana V. Poroseva; Nathan Lay; M. Yousuff Hussaini
Rb--Sr, K--Ar, and fission-track geochronological studies of samples from LASL drill holes GT-1, GT-2, and EE-1
Geochronological investigations using the Rb-Sr, K-Ar, and fission-track methods have been completed on core samples from the three LASL deep drill holes, GT-1, GT-2, and EE-1. This work indicates a complex history for these Precambrian rocks beginning with a metamorphic event at 1.66 b.y. which generated the gneisses and schists from older sedimentary and igneous rocks. The metamorphic complex was intruded by at least two different magmas at 1.3--1.4 b.y. producing thin felsic dikes and a major biotite granodiorite pluton. This igneous activity caused pervasive argon loss to occur, lowering the K-Ar ages to about 1.4 b.y. Plio-Pleistocene igneous activity related to formation of the Valles Caldera increased the local geothermal gradient to 50--60/sup 0/C/km and produced fission track annealing in apatite and again argon loss from the biotite in deeper samples.
Brookins, D.G.; Forbes, R.B.; Turner, D.L.; Laughlin, A.W.; Naeser, C.W.
Peer Effects, Teacher Incentives, and the Impact of Tracking: Evidence from a Randomized Evaluation in Kenya
To the extent that students benefit from high-achieving peers, tracking will help strong students and hurt weak ones. However, all students may benefit if tracking allows teachers to better tailor their instruction level. ...
Duflo, Esther
Observational Evidence for Alternate Modes of Track-Altering Binary Tropical Cyclone Scenarios
An observational study of western North Pacific tropical cyclones (TC) revealed many cases of two TCs whose tracks were altered by processes that were quite different from the mutual advection (Fujiwhara-type) processes. Thus, four conceptual ...
Lester E. Carr III; Mark A. Boothe; Russell L. Elsberry
Insights On The Thermal History Of The Valles Caldera, New Mexico- Evidence
Open Energy Info (EERE)
source source History View New Pages Recent Changes All Special Pages Semantic Search/Querying Get Involved Help Apps Datasets Community Login | Sign Up Search Page Edit History Facebook icon Twitter icon » Insights On The Thermal History Of The Valles Caldera, New Mexico- Evidence From Zircon Fission-Track Analysis Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Insights On The Thermal History Of The Valles Caldera, New Mexico- Evidence From Zircon Fission-Track Analysis Details Activities (2) Areas (1) Regions (0) Abstract: The zircon fission-track dating method was applied to the VC-2B core obtained from the active hydrothermal system at Sulphur Springs, Valles caldera, New Mexico. Four samples were analyzed to obtain both zircon ages and track length data from Permian strata to Precambrian quartz
Evidence of Diurnal Shelf Waves in Satellite-Tracked Drifter Trajectories off the Kuril Islands
Satellite-tracked surface drifters deployed in September 1993 in the vicinity of the Kuril–Kamchatka Trench were advected onto the Pacific continental shelf of the Kuril Islands where they encountered strong (40–50 cm s?1) diurnal tidal currents. ...
Alexander B. Rabinovich; Richard E. Thomson
7 8 5 - 8 8 9 9 Fiq. 24 A u + 618 MeV Kr Fission (cm. ) •lilt* Fission (lab)Non fission (lab) XBL 783-2453 Fig. 25
Moretto, L.G.
Interplanetary mission fission
NLE Websites -- All DOE Office Websites (Extended Search)
A new fission experiment demonstrates the viability of a small nuclear reactor to power solar-system-exploring spacecraft. July 15, 2013 Interplanetary mission fission Artist's...
Fission theory and actinide fission data
The understanding of the fission process has made great progress recently, as a result of the calculation of fission barriers, using the Strutinsky prescription. Double-humped shapes were obtained for nuclei in the actinide region. Such shapes could explain, in a coherent manner, many different phenomena: fission isomers, structure in near-threshold fission cross sections, intermediate structure in subthreshold fission cross sections and anisotropy in the emission of the fission fragments. A brief review of fission barrier calculations and relevant experimental data is presented. Calculations of fission cross sections, using double-humped barrier shapes and fission channel properties, as obtained from the data discussed previously, are given for some U and Pu isotopes. The fission channel theory of A. Bohr has greatly influenced the study of low-energy fission. However, recent investigation of the yields of prompt neutrons and ..gamma.. rays emitted in the resonances of /sup 235/U and /sup 239/Pu, together with the spin determination for many resonances of these two nuclei cannot be explained purely in terms of the Bohr theory. Variation in the prompt neutron and ..gamma..-ray yields from resonance to resonance does not seem to be due to such fission channels, as was thought previously, but to the effect of the (n, ..gamma.., f) reaction. The number of prompt fission neutrons and the kinetic energy of the fission fragments are affected by the energy balance and damping or viscosity effects in the last stage of the fission process, from saddle point to scission. These effects are discussed for some nuclei, especially for /sup 240/Pu. 17 figures, 56 ref. (auth)
Michaudon, A.
Fission theory: Its relevance to the nuclear cross section data base
The development of fission reaction theory in relation to its predictive power in the calculation of neutron cross-sections is reviewed. The topics covered include the transition state spectrum and the channel theory; the discovery of complex topography in the fission barrier and the consequences of intermediate structure in fission cross-sections; the evidence of experimental data in parameterizing the fission barrier; and the role of other aspects of collective nuclear motion in controlling fission reaction rates. 51 refs., 6 figs.
Lynn, J.E.
Statistical Model of Heavy-Ion Fusion-Fission Reactions
Cross-section and neutron-emission data from heavy-ion fusion-fission reactions are consistent with the fission of fully equilibrated systems with fission lifetime estimates obtained via a Kramers-modified statistical model which takes into account the collective motion of the system about the ground state, the temperature dependence of the location and height of fission transition points, and the orientation degree of freedom. If the standard techniques for calculating fission lifetimes are used, then the calculated excitation-energy dependence of fission lifetimes is incorrect. We see no evidence to suggest that the nuclear viscosity has a temperature dependence. The strong increase in the nuclear viscosity above a temperature of approximately 1.3 MeV deduced by others is an artifact generated by an inadequate fission model.
J. P. Lestone; S. G. McCalla
Fission Decay Widths for Heavy-Ion Fusion-Fission Reactions
Cross-section and neutron-emission data from heavy-ion fusion-fission reactions are consistent with a Kramers-modified statistical model which takes into account the collective motion of the system about the ground state; the temperature dependence of the location of fission transition points; and the orientation degree of freedom. We see no evidence to suggest that the nuclear viscosity departs from the surface-plus-window dissipation model. The strong increase in the nuclear viscosity above a temperature of ~1 MeV deduced by others is an artifact generated by an inadequate fission model.
S. G. McCalla; J. P. Lestone
BIOLOGICAL EVIDENCE disposition process
... Notification of destruction sent per statutory requirements In-house "tickler" system tracks evidence and identifies upcoming disposition time ...
Complex fission phenomena
Complex fission phenomena are studied in a unified way. Very general reflection asymmetrical equilibrium (saddle point) nuclear shapes are obtained by solving an integro-differential equation without being necessary to specify a certain parametrization. The mass asymmetry in binary cold fission of Th and U isotopes is explained as the result of adding a phenomenological shell correction to the liquid drop model deformation energy. Applications to binary, ternary, and quaternary fission are outlined.
D. N. Poenaru; R. A. Gherghescu; W. Greiner
A search for inverse fission of uranium
There is a long-term interest in running the fission reaction backward, i.e., studying the 'inverse fission' of uranium. The recent availability of beams of n-rich fission fragments has stimulated interest in this endeavor. The purpose is to search for inverse fission in the reactions {sup 124,132}Sn + {sup 100}Mo. In the {sup 124}Sn + {sup 100}Mo reaction, evaporation residues were searched for using in-beam detection of evaporation residues, in-beam {alpha} spectroscopy, and post-irradiation {alpha} spectroscopy, while in the {sup 132}Sn + {sup 100}Mo reaction, the evaporation residue {sup 230}U was searched for using post-irradiation {alpha} spectroscopy. No evidence for the occurrence of the inverse fission reactions was found. The upper-limit cross section for the latter reaction is {approx}550 {mu}b, while the experimental upper-limit cross section for the former reaction is about 21{sup -21}{sup +38} nb. The intensity of suitable radioactive beams is not high enough at present to detect inverse fission. For the {sup 124}Sn + {sup 100}Mo reaction, the observed upper limits are below the estimates of current models for these reactions, probably due to fusion hindrance.
Yanez, R [Oregon State University, Corvallis; Loveland, Walter [Oregon State University; Beckerman, J. [Oregon State University, Corvallis; Leonard, M. [Oregon State University, Corvallis; Pettersson, G. [Oregon State University, Corvallis; Gross, Carl J [ORNL; Shapira, Dan [ORNL; Liang, J Felix [ORNL; Kohley, Zachary W [ORNL; Varner Jr, Robert L [ORNL
Delayed-fission properties of neutron-deficient americium nuclei
Characteristics of the delayed-fission decay mode in light americium nuclei have been investigated. Measurements on the unknown isotopes {sup 230}Am and {sup 236}Am were attempted, and upper limits on the delayed-fission branches of these nuclei were determined. Evidence of the existence of {sup 236}Am was observed in radiochemical separations. Total kinetic energy and mass-yield distributions of the electron-capture delayed-fission mode were measured for {sup 232}Am (t{sub 1/2} = 1.31 {plus minus} 0.04 min) and for {sup 234}Am (t{sub 1/2} = 2.32 {plus minus} 0.08 min), and delayed-fission probabilities of 6.9 {times} 10{sup {minus}4} and 6.6 {times} 10{sup {minus}5}, respectively, were determined. The total kinetic energy and the asymmetric mass-yield distributions are typical of fission of mid-range actinides. No discernible influence of the anomalous triple-peaked mass division characteristic of the thorium-radium region was detected. Measurements of the time correlation between the electron-capture x-rays and the subsequent fission conform that the observed fissions arise from the electron-capture delayed-fission mechanism. Delayed fission has provided a unique opportunity to extend the range of low-energy fission studies to previously inaccessible regions. 71 refs., 44 figs., 13 tabs.
Hall, H.L. (California Univ., Berkeley, CA (USA). Dept. of Chemistry)
Fission gas detection system
DOE Patents (OSTI)
A device for collecting fission gas released by a failed fuel rod which device uses a filter to pass coolant but which filter blocks fission gas bubbles which cannot pass through the filter due to the surface tension of the bubble.
Colburn, Richard P. (Pasco, WA)
Emilio Segrč and Spontaneous Fission
Office of Scientific and Technical Information (OSTI)
however, had revealed that the uranium fissioned instead. The discovery of fission led in turn to the discovery of the chain reaction that, if sustained, would provide the...
Fission Energy Release for 16 Fissioning Nuclides
This report describes results of a study of fission energy releases and the components of this energy. Energy releases for primary isotopes, for which relatively good experimental quantities exist, were determined by a combination of mass-defect systematics and least-square fits with the experimental data. Only the systematic study was carried out for the remaining isotopes.
Overview of Fission Safety for Laser ICF Fission Energy
Laser Fusion-Fission Hybrid / Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 2)
Per F. Peterson; Edward Blandford; Christhian Galvez
Singlet fission photovoltaics
The efficiency of a solar cell is restricted by the "single junction limit," whereby photons with energy higher than the bandgap lose energy by thermalization. Singlet exciton fission splits a high-energy molecular excitation ...
Lee, Jiye
3He- and 4He-induced nuclear fission - a test of the transition state method
Fission in 3He and 4He induced reactions at excitation energies between the fission barrier and 140 MeV has been investigated. Twentythree fission excitation functions of various compound nuclei in different mass regions are shown to scale exactly according to the transition state prediction once the shell effects are accounted for. New precise measurements of excitation functions in a mass region where shell effects are very strong, allow one to test the predictions with an even higher accuracy. The fact that no deviations from the transition state method have been observed within the experimentally investigated excitation energy regime allows one to assign limits for the fission transient time. The precise measurement of fission excitation functions of neighboring isotopes enables us to experimentally estimate the first chance fission probability. Even if only first chance fission is investigated, no evidence for fission transient times larger than 30 zs can be found.
Th. Rubehn; K. X. Jing; L. G. Moretto; L. Phair; K. Tso; G. J. Wozniak
The Fission of Thorium with Alpha Particles
fissi on distribution of fission of thor ium v'jith alphaafter the discovery of fission, Meitner and Bretscher andin the distribution of fission products in the two . !
Newton, Amos S.
Fission product behavior in the Molten Salt Reactor Experiment
Essentially all the fission product data for numerous and varied samples taken during operation of the Molten Salt Reactor Experiment or as part of the examination of specimens removed after particular phases of operation are reported, together with the appropriate inventory or other basis of comparison, and relevant reactor parameters and conditions. Fission product behavior fell into distinct chemical groups. Evidence for fission product behavior during operation over a period of 26 months with $sup 235$U fuel (more than 9000 effective full-power hours) was consistent with behavior during operation using $sup 233$U fuel over a period of about 15 months (more than 5100 effective full- power hours). (auth)
Compere, E.L.; Kirslis, S.S.; Bohlmann, E.G.; Blankenship, F.F.; Grimes, W.R.
Mirror fusion--fission hybrids
The fusion-fission concept and the mirror fusion-fission hybrid program are outlined. Magnetic mirror fusion drivers and blankets for hybrid reactors are discussed. Results of system analyses are presented and a reference design is described.
Lee, J.D.
Radiochemistry of the fission products
This paper discusses the historical aspects of the radiochemistry of fission products. 20 figs., 2 tabs. (LSP)
Steinberg, E.P.
Process for treating fission waste
A method is described for the treatment of fission waste. A glass forming agent, a metal oxide, and a reducing agent are mixed with the fission waste and the mixture is heated. After melting, the mixture separates into a glass phase and a metal phase. The glass phase may be used to safely store the fission waste, while the metal phase contains noble metals recovered from the fission waste.
Rohrmann, Charles A. (Kennewick, WA); Wick, Oswald J. (Richland, WA)
Microscopic Description of Induced Fission
Selected aspects of the description of neutron-induced fission in 240Pu in the framework of the nuclear energy density functional theory at finite temperature are presented. In particular, we discuss aspects pertaining to the choice of thermodynamic state variables, the evolution of fission barriers as function of the incident neutron energy, and the temperatures of the fission fragments.
N. Schunck
Contract NO e W~7405~eng~4B "FISSION" OF w~IU11 w~IGHT EL~~California May The fission reaction has been observed withmore properly be termed fission, Cu b3 As an example 9 the
Batzel., Roger T.; Seaborg, G.T.
Infrared Spectroscopy of Wild 2 Particle Hypervelocity Tracks in Stardust Aerogel: Evidence for the presence of Volatile Organics in Comet Dust
Infrared spectroscopy maps of some tracks, made by cometary dust from 81P/Wild 2 impacting Stardust aerogel, reveal an interesting distribution of volatile organic material. Out of six examined tracks three show presence of volatile organic components possibly injected into the aerogel during particle impacts. When particle tracks contained excess volatile organic material, they were found to be -CH{sub 2}-rich. Off-normal particle tracks could indicate impacts by lower velocity particles that could have bounced off the Whipple shield, therefore carry off some contamination from it. However, this theory is not supported by data that show excess organic-rich material in normal and off-normal particle tracks. It is clear that the population of cometary particles impacting the Stardust aerogel collectors also include grains that contained little or none of this volatile organic component. This observation is consistent with the highly heterogeneous nature of the collected grains, as seen by a multitude of other analytical techniques. We propose that at least some of the volatile organic material might be of cometary origin based on supporting data shown in this paper. However, we also acknowledge the presence of carbon (primarily as -CH{sub 3}) in the original aerogel, which complicates interpretation of these results.
Bajt, S; Sandford, S A; Flynn, G J; Matrajt, G; Snead, C J; Westphal, A J; Bradley, J P
Radiation Detection from Fission
This report briefly describes the neutrons and gamma rays emitted in fission, briefly discusses measurement methods, briefly discusses sources and detectors relevant to detection of shielded HEU in sealand containers, and lists the measurement possibilities for the various sources. The brief descriptions are supplemented by reference.
Mihalczo, J.
Tracking Hurricanes
There is widespread concern about the recent increase in North Atlantic hurricane activity. Results here suggest that fledgling storms tracking east to west at low latitudes are more likely to reach hurricane intensity than those traveling on a ...
James B. Elsner
on Physics of Nuclear Fission,
spin-tensor of orientation Experimental data on angular distributions of ? rays emitted from binary and ternary spontaneous fission of 252 Cf are analyzed. Their difference indicates that the alignment of fragments is higher in ternary fission than in binary one. The consequences of possible relation between the mechanism of ternary fission and the excitation of collective modes during the saddle- to-scission stage are discussed. ii
unknown authors
A REVIEW OF NUCLEAR FISSION. PART ONE. FISSION PHENOMENA AT LOW ENERGY. Revised Edition
The discovery of fission is described, and fission theory is outlined. The probability of fission is discussed. Distribution of mass and nuclear charge in fission is considered. Measurements of the kinetic energy of fission fragments are described. The emission of prompt neutrons, delayed neutrons, and gamma rays in fission is discussed. (M.C.G.)
Hyde, E.K.
Method for correcting for isotope burn-in effects in fission neutron dosimeters
A method is described for correcting for effect of isotope burn-in in fission neutron dosimeters. Two quantities are measured in order to quantify the "burn-in" contribution, namely P.sub.Z',A', the amount of (Z', A') isotope that is burned-in, and F.sub.Z', A', the fissions per unit volume produced in the (Z', A') isotope. To measure P.sub.Z', A', two solid state track recorder fission deposits are prepared from the very same material that comprises the fission neutron dosimeter, and the mass and mass density are measured. One of these deposits is exposed along with the fission neutron dosimeter, whereas the second deposit is subsequently used for observation of background. P.sub.Z', A' is then determined by conducting a second irradiation, wherein both the irradiated and unirradiated fission deposits are used in solid state track recorder dosimeters for observation of the absolute number of fissions per unit volume. The difference between the latter determines P.sub.Z', A' since the thermal neutron cross section is known. F.sub.Z', A' is obtained by using a fission neutron dosimeter for this specific isotope, which is exposed along with the original threshold fission neutron dosimeter to experience the same neutron flux-time history at the same location. In order to determine the fissions per unit volume produced in the isotope (Z', A') as it ingrows during the irradiation, B.sub.Z', A', from these observations, the neutron field must generally be either time independent or a separable function of time t and neutron energy E.
Gold, Raymond (Richland, WA); McElroy, William N. (Richland, WA)
SOGGY SADDLE THEORY OF FISSION L.G. Moretto and G. GuarinoMIWW The soggy saddle theory of fission L.6. Moretto and G.transition state theory of fission is generalized to allow
The Fission of thorium with Alpha Particles
cm 2 FIG. 2 YIELD OF SOME FISSION PRODUCTS FROM THORIUM +-in aalou.latlnl~ I tha fission yield ot tlla 2.3;; dnyci~S~~SIO NASS HO. FIG. I FISSION YIELD SPECTRUM OF THORIUM
private communication. The fission-barrier calculations arein the systematics of spontaneous-fission half lives, W. J.1955). H. Marshall Blann, Fission of Gold with 112-Mev C
Gordon, Glen E.; Larsh, Almon E.; Sikkeland, Torbjorn; Seaborg, Glenn T.
Post-scission fission theory: Neutron emission in fission
A survey of theoretical representations of two of the observables in neutron emission in fission is given, namely, the prompt fission neutron spectrum N (E) and the average prompt neutron multiplicity {bar {nu}}{sub p}. Early representations of the two observables are presented and their deficiencies are discussed. This is followed by summaries and examples of recent theoretical models for the calculation of these quantities. Emphasis is placed upon the predictability and accuracy of the recent models. In particular, the dependencies of N (E) and {bar {nu}}{sub p} upon the fissioning nucleus and its excitation energy are treated. Recent work in the calculation of the prompt fission neutron spectrum matrix N (E, E{sub n}), where E{sub n} is the energy of the neutron inducing fission, is then discussed. Concluding remarks address the current status of our ability to calculate these observables with confidence, the direction of future theoretical efforts, and limitations to current (and future) approaches.
Madland, D.G.
Study of electron-capture delayed fission in Am-232
An automated x-ray-fission coincidence system was designed and constructed by LLNL and Lawrence Berkeley National Laboratory (LBNL) for use inside the Gammasphere high efficiency gamma-ray detector array at LBNL. The x-ray-fission coincidence apparatus detection station consists of two surface barrier detectors (for detection of fission fragments) and two high-purity Ge (HPGe) planar x-ray detectors (for measurement of x-rays and low-energy gamma rays). The detection station is placed inside Gammasphere at the 88-Inch Cyclotron at LBNL and used in conjunction with Gammasphere to measure the x-rays, low-energy gamma-rays and fission fragments resulting from the ECDF process. A series of collaborative experiment between LLNL, LBNL, and LANL utilizing various components of the x-ray-fission coincidence apparatus to measure x-rays and gamma-rays in the decay of a stationary {sup 252}Cf source were performed to test the various components of the x-ray-fission coincidence apparatus. The test experiments have been completed and the data is currently being analyzed by LBNL. Preliminary test results indicate that the system performed better than expected (e.g., the x-ray detectors performed better than expected with no evidence of microphonic noise that would reduce the photon energy resolution).
Kreek, S.A.; Hall, H.L.; Hoffman, D.C. [Lawrence Livermore National Lab., CA (United States); Strellis, D. [Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering; Gregorich, K.E. [Lawrence Berkeley National Lab., CA (United States). Nuclear Science Div.
Fission modes of mercury isotopes
Background: Recent experiments on beta-delayed fission in the mercury-lead region and the discovery of asym- metric fission in 180 Hg [1] have stimulated theoretical interest in the mechanism of fission in heavy nuclei. Purpose: We study fission modes and fusion valleys in 180 Hg and 198 Hg to reveal the role of shell effects in pre-scission region and explain the experimentally observed fragment mass asymmetry and its variation with A. Methods: We use the self-consistent nuclear density functional theory employing Skyrme and Gogny energy density functionals. Results: The potential energy surfaces in multi-dimensional space of collective coordinates, including elongation, triaxiality, reflection-asymmetry, and necking, are calculated for 180 Hg and 198 Hg. The asymmetric fission valleys - well separated from fusion valleys associated with nearly spherical fragments - are found in in both cases. The density distributions at scission configurations are studied and related to the experimentally observed mass splits. Conclusions: The energy density functionals SkM\\ast and D1S give a very consistent description of the fission process in 180 Hg and 198 Hg. We predict a transition from asymmetric fission in 180 Hg towards more symmetric distribution of fission fragments in 198 Hg. For 180 Hg, both models yield 100 Ru/80 Kr as the most probable split. For 198 Hg, the most likely split is 108 Ru/90 Kr in HFB-D1S and 110 Ru/88 Kr in HFB-SkM\\ast.
M. Warda; A. Staszczak; W. Nazarewicz
Fission Modes of Mercury Isotopes
Background: Recent experiments on -delayed fission in the mercury-lead region and the discovery of asymmetric fission in 180Hg [A. N. Andreyev et al., Phys. Rev. Lett. 105, 252502 (2010)] have stimulated theoretical interest in the mechanism of fission in heavy nuclei. Purpose: We study fission modes and fusion valleys in 180Hg and 198Hg to reveal the role of shell effects in the prescission region and explain the experimentally observed fragment mass asymmetry and its variation with A. Methods: We use the self-consistent nuclear density functional theory employing Skyrme and Gogny energy density functionals. Results: The potential energy surfaces in multidimensional space of collective coordinates, including elongation, triaxiality, reflection-asymmetry, and necking, are calculated for 180Hg and 198Hg. The asymmetric fission valleys well separated from fusion valleys associated with nearly spherical fragments are found in both cases. The density distributions at scission configurations are studied and related to the experimentally observed mass splits. Conclusions: The energy density functionals SkM and D1S give a very consistent description of the fission process in 180Hg and 198Hg. We predict a transition from asymmetric fission in 180Hg toward a more symmetric distribution of fission fragments in 198Hg. For 180Hg, both models yield 100Ru/80Kr as the most probable split. For 198Hg, the most likely split is 108Ru/90Kr in HFB-D1S and 110Ru/88Kr in HFB-SkM .
Warda, M. [Maria Curie-Sk?odowska University-Poland; Staszczak, A. [Maria Curie-Sklodowska University; Nazarewicz, Witold [UTK/ORNL/University of Warsaw
Fission fragment driven neutron source
Fissionable uranium formed into a foil is bombarded with thermal neutrons in the presence of deuterium-tritium gas. The resulting fission fragments impart energy to accelerate deuterium and tritium particles which in turn provide approximately 14 MeV neutrons by the reactions t(d,n).sup.4 He and d(t,n).sup.4 He.
Miller, Lowell G. (Idaho Falls, ID); Young, Robert C. (Idaho Falls, ID); Brugger, Robert M. (Columbia, MO)
Fission throughout the periodic table
The dualistic view of fission and evaporation as two distinct compound nucleus processes is substituted with a unified view in which fission, complex fragment emission, and light particle evaporation are seen as different aspects of a single process. 47 refs., 22 figs.
Moretto, L.G.; Wozniak, G.J.
A pyrogenic method of separating nuclear reactor waste solutions containing aluminum and fission products as buring petroleum coke in an underground retort, collecting the easily volatile gases resulting as the first fraction, he uminum chloride as the second fraction, permitting the coke bed to cool and ll contain all the longest lived radioactive fission products in greatly reduced volume.
Huff, J.B.
and J. R. Huizenga, Nuclear Fission (to be published inHeavy-lon-Induced Nuclear Fission, (to be published in Proc.
High resolution track etch autoradiography
A detector assembly is disclosed for use in obtaining alpha-track autoradiographs, the detector assembly including a substantially boron-free substrate; a detector layer deposited on the substantially boron-free substrate, the detector layer being capable of recording alpha particle tracks and exhibiting evidence of the alpha tracks in response to being exposed to an etchant, the detector layer being less than about 2 microns thick; and a protective layer deposited on the detector layer, the protective layer being resistant to the etchant and having a thickness of about 0.5 to 1 microns. 13 figures.
Solares, G.; Zamenhof, R.G.
A detector assembly for use in obtaining alpha-track autoradiographs, the detector assembly including a substantially boron-free substrate; a detector layer deposited on the substantially boron-free substrate, the detector layer being capable of recording alpha particle tracks and exhibiting evidence of the alpha tracks in response to being exposed to an etchant, the detector layer being less than about 2 microns thick; and a protective layer deposited on the detector layer, the protective layer being resistant to the etchant and having a thickness of about 0.5 to 1 microns.
Solares, Guido (Arlington, MA); Zamenhof, Robert G. (Brookline, MA)
Historical Tracking
...Historical tracking is a process of measuring, recording, and analyzing one or more specific characteristics of a process. This record then becomes the basis on which the current state of the process can be assessed and the future state of the process predicted....
Composite Ship Track Characteristics
The physical and radiative properties of a composite ship track are described from the analysis of 131 ship–ship track correlation pairs collected during the Monterey Area Ship Track experiment. The significant variability of ship tracks around ...
P. A. Durkee; R. E. Chartier; A. Brown; E. J. Trehubenko; S. D. Rogerson; C. Skupniewicz; K. E. Nielsen; S. Platnick; M. D. King
More on the term ŤFission?
information, and he certainly did. His insight into the origin of the term "fission" expanded greatly on the mere mention I had made of it in the Y-12 history column he...
The microscopic theory of fission
Fission-fragment properties have been calculated for thermal neutron-induced fission on a $^{239}\\textrm{Pu}$ target, using constrained Hartree-Fock-Bogoliubov calculations with a finite-range effective interaction. A quantitative criterion based on the interaction energy between the nascent fragments is introduced to define the scission configurations. The validity of this criterion is benchmarked against experimental measurements of the kinetic energies and of multiplicities of neutrons emitted by the fragments.
W. Younes; D. Gogny
University of California. FISSION YIELDS AL\\JD LIFETIMES FORfor his assistance in the fission chamber calibrations andCl8 (1978) 1452. Table 1 Fission yields yf Nucleus 23su 23Su
Ahmad, S.
Fail-safe source-driven fission and fusion-fission hybrid reactor configurations.
??A source-driven nuclear reactor configuration with a unity infinite medium multiplication factor fission core (1k??), is investigated for both fission and fusion-fission hybrid systems. Suchaconfiguration… (more)
Singh, Monish
Nuclear Fission: Reaction to the Discovery in 1939
and A. v. Grosse, "Nuclear fission of separated uraniumThe mechanism of nuclear fission," Physical Review, 56 (1liberated in the nuclear fission of uranium," Nature, 143 (
Hodes, Elizabeth; Tiddens, Adolph; Badash, Lawrence
strongly damped nuclear collisions and in fission. This work48, In nuclear collisions and in fission the fluctuations instages of fission and strongly damped nuclear collisions the
Myers, W.D.
ZIRCALOY WITH SIMULATED FISSION PRODUCTS Rajiv Kohli JanuaryOF ZIRCALOY WITH SIMULATED FISSION PRODUCTS Rajiv Kohlion long-term exposure to fission product environments in the
Kohli, R.
Logging Calibration Models for Fission Neutron Sondes (September...
Energy.gov (U.S. Department of Energy (DOE)) Indexed Site
Logging Calibration Models for Fission Neutron Sondes (September 1981) Logging Calibration Models for Fission Neutron Sondes (September 1981) Logging Calibration Models for Fission...
Spallation Cro ss Sections Fission Product Cross Sections V.B. Spallation Reactions Fission Yields Acknowledgme nts . .UNIVERSITY OF CALIFORNIA ;"~I FISSION SPALLATION EXCITATION
Ritsema, Susanne Elaine
Fission product solvent extraction
Two main objectives concerning removal of fission products from high-level tank wastes will be accomplished in this project. The first objective entails the development of an acid-side Cs solvent-extraction (SX) process applicable to remediation of the sodium-bearing waste (SBW) and dissolved calcine waste (DCW) at INEEL. The second objective is to develop alkaline-side SX processes for the combined removal of Tc, Cs, and possibly Sr and for individual separation of Tc (alone or together with Sr) and Cs. These alkaline-side processes apply to tank wastes stored at Hanford, Savannah River, and Oak Ridge. This work exploits the useful properties of crown ethers and calixarenes and has shown that such compounds may be economically adapted to practical processing conditions. Potential benefits for both acid- and alkaline-side processing include order-of-magnitude concentration factors, high rejection of bulk sodium and potassium salts, and stripping with dilute (typically 10 mM) nitric acid. These benefits minimize the subsequent burden on the very expensive vitrification and storage of the high-activity waste. In the case of the SRTALK process for Tc extraction as pertechnetate anion from alkaline waste, such benefits have now been proven at the scale of a 12-stage flowsheet tested in 2-cm centrifugal contactors with a Hanford supernatant waste simulant. SRTALK employs a crown ether in a TBP-modified aliphatic kerosene diluent, is economically competitive with other applicable separation processes being considered, and has been successfully tested in batch extraction of actual Hanford double-shell slurry feed (DSSF).
Moyer, B.A.; Bonnesen, P.V.; Sachleben, R.A. [and others
Compact fission counter for DANCE
The Detector for Advanced Neutron Capture Experiments (DANCE) consists of 160 BF{sub 2} crystals with equal solid-angle coverage. DANCE is a 4{pi} {gamma}-ray calorimeter and designed to study the neutron-capture reactions on small quantities of radioactive and rare stable nuclei. These reactions are important for the radiochemistry applications and modeling the element production in stars. The recognition of capture event is made by the summed {gamma}-ray energy which is equivalent of the reaction Q-value and unique for a given capture reaction. For a selective group of actinides, where the neutron-induced fission reaction competes favorably with the neutron capture reaction, additional signature is needed to distinguish between fission and capture {gamma} rays for the DANCE measurement. This can be accomplished by introducing a detector system to tag fission fragments and thus establish a unique signature for the fission event. Once this system is implemented, one has the opportunity to study not only the capture but also fission reactions. A parallel-plate avalanche counter (PPAC) has many advantages for the detection of heavy charged particles such as fission fragments. These include fast timing, resistance to radiation damage, and tolerance of high counting rate. A PPAC also can be tuned to be insensitive to {alpha} particles, which is important for experiments with {alpha}-emitting actinides. Therefore, a PPAC is an ideal detector for experiments requiring a fast and clean trigger for fission. A PPAC with an ingenious design was fabricated in 2006 by integrating amplifiers into the target assembly. However, this counter was proved to be unsuitable for this application because of issues related to the stability of amplifiers and the ability to separate fission fragments from {alpha}'s. Therefore, a new design is needed. A LLNL proposal to develop a new PPAC for DANCE was funded by NA22 in FY09. The design goal is to minimize the mass for the proposed counter and still be able to maintain a stable operation under extreme radioactivity and the ability to separate fission fragments from {alpha}'s. In the following sections, the description is given for the design and performance of this new compact PPAC, for studying the neutron-induced reactions on actinides using DANCE at LANL.
Wu, C Y; Chyzh, A; Kwan, E; Henderson, R; Gostic, J; Carter, D; Bredeweg, T; Couture, A; Jandel, M; Ullmann, J
Flexible data fusion (& fission)
An approach is described for developing methods for "data fusion": given how events A & B occurring by themselves influence some measure, estimate the influence (on that measure) of A and B occurring together. An example is "combine the effects of evidence ...
Alexander Yeh
Entrance-channel dependence of fission transients
Fission transients describe the fission rate as it evolves towards the quasistationary value given by Kramers' formula. The nature of fission transients is dependent on the assumed initial distribution of the compound nuclei along the fission coordinate. Although the standard initial assumption of a near-spherical object leads to a transient suppression of the fission rate (fission delay), a moderate initial fissionlike deformation can reduce the magnitude of this suppression. For still larger initial deformations, transient fission enhancements are possible. Examples of this behavior are illustrated via a one-dimensional Langevin simulation. It is argued that the initial conditions are determined by the fusion dynamics and thus are entrance-channel dependent. Transient fission may be considered intermediate between statistical fission and quasifission as the rapid time scale of transient fission may not lead to an equilibrium of the angular and mass-asymmetry coordinates. The relationship between the mean first passage time and the transients are discussed. For temperatures much smaller than the fission barrier, the mean first passage time is independent of the nature of the fission transients if there is no strong competition from evaporation. Thus, fission transients are most important when the evaporation time scale is smaller than, or of the order of, the transient time.
R. J. Charity
Cranking mass parameters for fission
A formalism for semi-adiabatic cranking mass parameters is presented. For the fission process of 234U, the time-dependent pairing equations of motion were used to calculate the excitation energy and to extract values of the cranking inertia. A fission barrier is determined by minimizing the action trajectory in a five dimensional configuration space spanned by elongation, necking, deformations of fragments and mass-asymmetry. The deformation energy is computed in the the frame of the microscopic-macroscopic model. The two center shell model with Woods-Saxon potentials is used in this context. Values of the inertia for excited fissioning systems are reported. A dependence between the cranking mass parameters and the intrinsic excitation energy is evidenced.
M. Mirea; R. C. Bobulescu
Atomistic simulation of track formation by energetic ions in zircon
We have performed classical molecular dynamics simulations of fission track formation in zircon. We simulated the passage of a swift heavy ion through crystalline zircon using cylindrical thermal spikes with energy deposition (dE/dx) of 2.5-12.8 keV nm{sup -1} and a radius of 3 nm. At a low dE/dx of 2.55 keV nm{sup -1}, the structural damage recovered almost completely and a damage track was not produced. At higher values of dE/dx, tracks were observed and the radius of the track increased with increasing dE/dx. Our structural analysis shows amorphization in the core of the track and phase separation into Si-rich regions near the center of the track and Zr-rich regions near the periphery. These simulations establish a threshold dE/dx for fission track formation in zircon that is relevant to thermochronology and nuclear waste immobilization.
Moreira, Pedro A.F.P. [Universidade Estadual de Campinas, Sao Paulo; Devanathan, Ram [Pacific Northwest National Laboratory (PNNL); Weber, William J [ORNL
The nucleon phase hypothesis of binary fission
The mass distribution of fission fragments of actinide and superheavy nuclei can be explained if a new state of nuclear matter, a nucleon phase, is created in any fission event.
G. Mouze; S. Hachem; C. Ythier
Mouze, G; Ythier, C
Quantum efficiency and fission rate in tetracene
Using singlet fission in a photovoltaic cell, the theoretical energy conversion efficiency limit is larger than the Shockley-Queisser limit due to two excitons produced with one incident photon. In a singlet fission material, ...
Wu, Tony Chang-Chi
This patent broadly discloses the production of plutonium by the neutron bombardment of uranium to produce neptunium which decays to plutonium, and the fissionability of plutonium by neutrons, both fast and thermal, to produce energy and fission products.
Segre, E.; Kennedy, J.W.; Seaborg, G.T.
Neutronics for critical fission reactors and subcritical fission in hybrids
The requirements of future innovative nuclear fuel cycles will focus on safety, sustainability and radioactive waste minimization. Critical fast neutron reactors and sub-critical, external source driven systems (accelerator driven and fusion-fission hybrids) have a potential role to meet these requirements in view of their physics characteristics. This paper provides a short introduction to these features.
Salvatores, Massimo [CEA-Cadarache, DEN-Dir, Bat. 101, St-Paul-Lez-Durance 13108 (France)
The Metabolic Properties of the Fission Products and Actinide Elements
directly from nuclear fission. Radioactive substances can··free Fission Prodl,wts in the Rat" Natl Nuclear Energy
Hamilton M.D., J.G.
strongly damped nuclear collisions or in fission. Since theDistribution in Fission William 0. Myers Nuclear Science
Nuclear fission in covariant density functional theory
The current status of the application of covariant density functional theory to microscopic description of nuclear fission with main emphasis on superheavy nuclei (SHN) is reviewed. The softness of SHN in the triaxial plane leads to an emergence of several competing fission pathes in the region of the inner fission barrier in some of these nuclei. The outer fission barriers of SHN are considerably affected both by triaxiality and octupole deformation.
A. V. Afanasjev; H. Abusara; P. Ring
Axisymmetric Magnetic Mirror Fusion-Fission Hybrid
Fusion-Fission Hybrids and Transmutation / Proceedings of the Fifteenth International Conference on Emerging Nuclear Energy Systems
R. W. Moir; N. N. Martovetsky; A. W. Molvik; D. D. Ryutov; T. C. Simonen
Multiple-Coincidence Interrogation of Fissionables
The multiple coincidence technique uses 14.1 MeV neutrons to produce (n, multiple-?) coincidences to detect fissile and fissionable materials. Measurements of n-?-? coincidences with targets of depleted uranium (DU), W, and Pb, show that the counting rate for the DU is substantially above that for the non-fissionables. Also, the data involving prompt neutrons and delayed gammas in the DU time spectra provide a signature for fissionables that is distinct from that of non-fissionables.
J.P. Hurley, R.P. Keegan, J.R. Tinsley, R. Trainham
Process for treating fission waste. [Patent application
Rohrmann, C.A.; Wick, O.J.
Tracking the Libor Rate
Paper 1108R2 Paper 1108R) Tracking the Libor Rate Rosa M.revision 2013 by author(s). Tracking the Libor Rate Rosa M.providing a methodology for tracking the dynamic integrity
Abrantes-Metz, Rosa; Villas-Boas, Sofia B.; Judge, George G.
Electromechanical solar tracking apparatus
The invention relates to an electromechanical solar tracking device which tracks the position of the sun using paired, partially-shaded bimetallic elements.
Stromberg, Robert P. (Albuquerque, NM)
Status update on the NIFFTE high precision fission cross section measurement program
The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) program has been underway for nearly two years. The program's mission is to measure fission cross sections of the primary fissionable and fissile materials ({sup 235}U, {sup 239}Pu, {sup 238}U) as well as the minor actinides across energies from approximately 50 keV up to 20 MeV with an absolute uncertainty of less than one percent while investigating energy ranges from below an eV to 600 MeV. This basic nuclear physics data is being reinvestigated to support the next generation power plants and a fast burner reactor program. Uncertainties in the fast, resolved and unresolved resonance regions in plutonium and other transuranics are extremely large, dominating safety margins in the next generation nuclear power plants and power plants of today. This basic nuclear data can be used to support all aspects of the nuciear renaissance. The measurement campaign is utilizing a Time Projection Chamber or TPC as the tool to measure these cross sections to these unprecedented levels. Unlike traditional fission cross section measurements using time-of-flight and a multiple fission foil configurations in which fission cross sections in relation to that of {sup 235}U are performed, the TPC project uses time-of-flight and hydrogen as the benchmark cross section. Using the switch to hydrogen, a simple, smooth cross section that can be used which removes the uncertainties associated with the resolved and unresolved resonances in {sup 235}U.
Laptev, Alexander B [Los Alamos National Laboratory; Tovesson, Fredrik [Los Alamos National Laboratory; Burgett, Eric [GEORGIA INSTITUTE OF TECH; Greife, Uwe [COLORADO SCHOOL OF THE MINES; Grimes, Steven [OHIO UNIV; Heffner, Michael D [LLNL; Hertel, Nolan E [GEORGIA INSTITUTE OF TECH; Hill, Tony [IDAHO NATIONAL LABORATORY; Isenhower, Donald [ABILENE CHRISTIN UNIV; Klay, Jennifer L [CALIFORNIA POLYTECHNIC STATE UNIV; Kornilov, Nickolay [OHIO UNIV; Kudo, Ryuho [CALIFORNIA POLYTECHNIC STATE UNIV; Loveland, Walter [OREGON STATE UNIV; Massey, Thomas [OHIO UNIV; Mc Grath, Chris [IDAHO NATIONAL LABORATORY; Pickle, Nathan [ABILENE CHRISTIAN UNIV; Qu, Hai [ABILENE CHRISTIAN UNIV; Sharma, Sarvagya [ABILENE CHRISTIAN UNIV; Snyder, Lucas [COLORADO SCHOOL OF THE MINES; Thornton, Tyler [ABILENE CHRISTIAN UNIV; Towell, Rusty S [ABILENE CHRISTIAN UNIV; Watson, Shon [ABILENE CHRISTIAN UNIV
Microscopic Description of Nuclear Fission Dynamics
We discuss possible avenues to study fission dynamics starting from a time-dependent mean-field approach. Previous attempts to study fission dynamics using the time-dependent Hartree-Fock (TDHF) theory are analyzed. We argue that different initial conditions may be needed to describe fission dynamics depending on the specifics of the fission phenomenon and propose various approaches towards this goal. In particular, we provide preliminary calculations for studying fission following a heavy-ion reaction using TDHF with a density contraint. Regarding prompt muon-induced fission, we also suggest a new approach for combining the time-evolution of the muonic wave function with a microscopic treatment of fission dynamics via TDHF.
A. S. Umar; V. E. Oberacker; J. A. Maruhn; P. -G. Reinhard
Fission dynamics at low excitation energy
The origin of mass asymmetry in the fission of uranium at a low excitation energy is clarified by a trajectory analysis of the Langevin equation. The positions of the peaks in the mass distribution of fission fragments are mainly determined by fission saddle points originating from the shell correction energy. The widths of the peaks, on the other hand, result from a shape fluctuation around the scission point caused by the random force in the Langevin equation. We found that a random vibration in the oblate direction of fissioning fragments is essential for the fission process. According to this picture, fission does not occur with continuous stretching in the prolate direction, similarly to that observed in starch syrup. This is expected to lead to a new viewpoint of fission dynamics and the splitting mechanism.
Y. Aritomo; S. Chiba
Fusion-Fission Hybrid for Fissile Fuel Production without Processing
Two scenarios are typically envisioned for thorium fuel cycles: 'open' cycles based on irradiation of {sup 232}Th and fission of {sup 233}U in situ without reprocessing or 'closed' cycles based on irradiation of {sup 232}Th followed by reprocessing, and recycling of {sup 233}U either in situ or in critical fission reactors. This study evaluates a third option based on the possibility of breeding fissile material in a fusion-fission hybrid reactor and burning the same fuel in a critical reactor without any reprocessing or reconditioning. This fuel cycle requires the hybrid and the critical reactor to use the same fuel form. TRISO particles embedded in carbon pebbles were selected as the preferred form of fuel and an inertial laser fusion system featuring a subcritical blanket was combined with critical pebble bed reactors, either gas-cooled or liquid-salt-cooled. The hybrid reactor was modeled based on the earlier, hybrid version of the LLNL Laser Inertial Fusion Energy (LIFE1) system, whereas the critical reactors were modeled according to the Pebble Bed Modular Reactor (PBMR) and the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) design. An extensive neutronic analysis was carried out for both the hybrid and the fission reactors in order to track the fuel composition at each stage of the fuel cycle and ultimately determine the plant support ratio, which has been defined as the ratio between the thermal power generated in fission reactors and the fusion power required to breed the fissile fuel burnt in these fission reactors. It was found that the maximum attainable plant support ratio for a thorium fuel cycle that employs neither enrichment nor reprocessing is about 2. This requires tuning the neutron energy towards high energy for breeding and towards thermal energy for burning. A high fuel loading in the pebbles allows a faster spectrum in the hybrid blanket; mixing dummy carbon pebbles with fuel pebbles enables a softer spectrum in the critical reactors. This combination consumes about 20% of the thorium initially loaded in the hybrid reactor ({approx}200 GWd/tHM), partially during hybrid operation, but mostly during operation in the critical reactor. The plant support ratio is low compared to the one attainable using continuous fuel chemical reprocessing, which can yield a plant support ratio of about 20, but the resulting fuel cycle offers better proliferation resistance as fissile material is never separated from the other fuel components.
Fratoni, M; Moir, R W; Kramer, K J; Latkowski, J F; Meier, W R; Powers, J J
Nuclear-fission studies with relativistic secondary beams: analysis of fission channels
Nuclear fission of several neutron-deficient actinides and pre-actinides from excitation energies around 11 MeV was studied at GSI Darmstadt by use of relativistic secondary beams. The characteristics of multimodal fission of nuclei around 226Th are systematically investigated and interpreted as the superposition of three fission channels. Properties of these fission channels have been determined for 15 systems. A global view on the properties of fission channels including previous results is presented. The positions of the asymmetric fission channels are found to be constant in element number over the whole range of systems investigated.
C. Boeckstiegel; S. Steinhaeuser; K. -H. Schmidt; H. -G. Clerc; A. Grewe; A. Heinz; M. de Jong; A. R. Junghans; J. Mueller; B. Voss
Fission Properties for R-Process Nuclei
We present a systematics of fission barriers and fission lifetimes for the whole landscape of superheavy elements (SHE), i.e., nuclei with Z 100. The fission lifetimes are also compared with the -decay half-lives. The survey is based on a self-consistent description in terms of the Skyrme-Hartree-Fock (SHF) approach. Results for various different SHF parametrizations are compared to explore the robustness of the predictions. The fission path is computed by quadrupole constrained SHF. The computation of fission lifetimes takes care of the crucial ingredients of the large-amplitude collective dynamics along the fission path, as self-consistent collective mass and proper quantum corrections. We discuss the different topologies of fission landscapes which occur in the realm of SHE (symmetric versus asymmetric fission, regions of triaxial fission, bimodal fission, and the impact of asymmetric ground states). The explored region is extended deep into the regime of very neutron-rich isotopes as they are expected to be produced in the astrophysical r process.
Erler, J. [Inst. fur Theoretische Physik II, Univ. Erlangen-Numberg, Germany/UTK/ORNL; Langanke, K. [GSI-Darmstadt/Tech. Univ. Darmstadt, Inst. Phys./Frankfurt Inst. Advanced Studies, Germany; Loens, H. P. [GSI-Darmstadt/Tech. Univ. Darmstadt, Inst. Phys.; Martinez-Pinedo, G. [GSI-Darmstadt/Tech. Univ. Darmstadt, Inst. Phys.; Reinhard, P.-G. [Inst. fur Theoretische Physik II, Univ. Erlangen-Numberg, Germany
Fission properties for r-process nuclei
We present a systematics of fission barriers and fission lifetimes for the whole landscape of super-heavy elements (SHE), i.e. nuclei with Z>100. The fission lifetimes are also compared with the alpha-decay half-lives. The survey is based on a self-consistent description in terms of the Skyrme-Hartree-Fock (SHF) approach. Results for various different SHF parameterizations are compared to explore the robustness of the predictions. The fission path is computed by quadrupole constrained SHF. The computation of fission lifetimes takes care of the crucial ingredients of the large-amplitude collective dynamics along the fission path, as self-consistent collective mass and proper quantum corrections. We discuss the different topologies of fission landscapes which occur in the realm of SHE (symmetric versus asymmetric fission, regions of triaxial fission, bi-modal fission, and the impact of asymmetric ground states). The explored region is extended deep into the regime of very neutron-rich isotopes as they are expected to be produced in the astrophysical r process.
J. Erler; K. Langanke; H. P. Loens; G. Martínez-Pinedo; P. -G. Reinhard
Isoscaling behavior in the Fission Dynamics
The fission processes of $^{112}$Sn + $^{112}$Sn and $^{116}$Sn + $^{116}$Sn are simulated with the combination of the Langevin equation and the statistical decay model. The masses of two fission fragments are given by assuming the process of symmetric fission or asymmetric fission by the Monte Carlo sampling with the Gaussian probability distribution. From the analysis to the isotopic/isotonic ratios of the fission fragments from both reactions, the isoscaling behavior has been observed and investigated in details. Isoscaling parameters $\\alpha$ and $\\beta$ are extracted as a function of the charge number and neutron number, respectively, in different width of the sampling Gaussian probability distribution. It seems that $\\alpha$ is sensitive to the width of fission probability distribution of the mass asymmetrical parameter but $\\beta$ is not. Both $\\alpha$ and $\\beta$ drop with the increasing of beam energy and the reduced friction parameter.
Y. G. Ma; K. Wang; X. Z. Cai; J. G. Chen; J. H. Chen; D. Q. Fang; W. Guo; C. W. Ma; G. L. Ma; W. Q. Shen; Q. M. Su; W. D. Tian; Y. B. Wei; T. Z. Yan; C. Zhong; X. F. Zhou; J. X. Zuo
Fission barriers and half-lives
We briefly review the development of theoretical models for the calculation of fission barriers and half-lives. We focus on how results of actual calculations in a unified macroscopic-microscopic approach provide an interpretation of the mechanisms behind some of the large number of phenomena observed in fission. As instructive examples we choose studies of the rapidly varying fission properties of elements at the end of the periodic system. 31 refs., 10 figs.
Moeller, P.; Nix, J.R.; Swiatecki, W.J.
A method is given for recovertng aluminum values from aqueous solutions containing said values together with fission products. A mixture of Fe/sub 2/O/ sub 3/ and MnO/sub 2/ is added to a solution containing aluminum and fission products. The resulting aluminum-containing supernatant is then separated from the fission product-bearing metal oxide precipitate and is contacted with a cation exchange resin. The aluminum sorbed on the resin is then eluted and recovered. (AEC)
Blanco, R.E.; Higgins, I.R.
The decontamination of organic solvents from fission products and in particular the treatment of solvents that were used for the extraction of uranium and/or plutonium from aqueous acid solutions of neutron-irradiated uranium are treated. The process broadly comprises heating manganese carbonate in air to a temperature of between 300 and 500 deg C whereby manganese dioxide is formed; mixing the manganese dioxide with the fission product-containing organic solvent to be treated whereby the fission products are precipitated on the manganese dioxide; and separating the fission product-containing manganese dioxide from the solvent.
Moore, R.H.
Carrier precipitation processes for separating plutonium values from uranium fission products are described. Silicon dioxide or titanium dioxide in a finely divided state is added to an acidic aqueous solution containing hexavalent plutonium ions together with ions of uranium fission products. The supernatant solution containing plutonium ions is then separated from the oxide and the fission products associated therewith.
Davies, T.H.
Fission fragment excited laser system
A laser system and method for exciting lasing action in a molecular gas lasing medium which includes cooling the lasing medium to a temperature below about 150 K and injecting fission fragments through the lasing medium so as to preferentially excite low lying vibrational levels of the medium and to cause population inversions therein. The cooled gas lasing medium should have a mass areal density of about 5 .times. 10.sup.-.sup.3 grams/square centimeter, relaxation times of greater than 50 microseconds, and a broad range of excitable vibrational levels which are excitable by molecular collisions.
McArthur, David A. (Albuquerque, NM); Tollefsrud, Philip B. (Albuquerque, NM)
Some Considerations on the Probability of Nuclear Fission
om THE PROBABILITY OF NUCLEAR FISSION Robert Vandenbosch andON TRE PROBABILITY OF NUCLEAR FISSION O E Contents Abstractf is the fission threshold, and the nuclear temperature T is
Vandenbosch, Robert; Seaborg, Glenn T.
the Charge Distribution in Fission William 0. Myers Nuclearnuclear collisions or in fission. Since the asymptotic widthin ref. [ 4] for the fission of ? 3fi U. As the neck between
with Application to Fission W. D. Myers, G. Mantzouranis andnuclear collisions and in fission. This work was supportedIn nuclear collisions and in fission the fluctuations in the
Tracking & Troubleshooting Online Vouchers
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Shull, Kenneth R.
Solar tracking apparatus
The invention relates to a solar tracking device which tracks the position of the sun using paired, partially-shaded photocells. Auxiliary photocells are used for initial acquisition of the sun and for the suppression of false tracking when the sun is obscured by clouds.
Hammons, Burrell E. (Albuquerque, NM)
The removal of fission products such as strontium, barium, cesium, rubidium, or iodine from neutronirradiated uranium is described. Uranium halide or elemental halogen is added to melted irradiated uranium to convert the fission products to either more volatile compositions which vaporize from the melt or to higher melting point compositions which separate as solids.
Spedding, F.H.; Butler, T.A.; Johns, I.B.
Fission properties of the BCPM functional
We explore the properties of the Barcelona Catania Paris Madrid (BCPM) energy density functional concerning fission dynamics. Potential energy surfaces as well as collective inertias relevant in the fission process are computed for several nuclei where experimental data exists. Inner and outer barrier heights as well as fission isomer excitation energies are reproduced quite well in all the cases. The spontaneous fission half lives $t_{\\textrm{\\textrm{SF}}}$ are also computed using the standard semiclassical approach and the results are compared with the experimental data. A reasonable agreement with experiment is found over a range of 27 orders of magnitude but the theoretical predictions suffer from large uncertainties associated to the values of the parameters entering the spontaneous fission half life formula. The impact that increasing the pairing correlations strengths has in the spontaneous fission half lives is analyzed and found to be large in all the nuclei considered. Given the satisfactory description of the trend of fission properties with mass number we explore the fission properties of the even-even uranium isotope chain from $^{226}$U to $^{282}$U. Very large half lives are found when getting close to neutron number N=184.
Samuel A. Giuliani; Luis M. Robledo
A source of fission product recoil energy suitable for use in radiation chemistry is reported. The source consists of thermal neutron irradiated glass wool having a diameter of 1 to 5 microns and containing an isotope fissionable by thermal neutrons, such as U/sup 235/.
Harteck, P.; Dondes, S.
Formation and Incorporation Energies of Fission Gases He, Xe, and ...
Presentation Title, Formation and Incorporation Energies of Fission Gases He, Xe , ... nuclear fuels are bcc alloys of uranium that swell under fission conditions, ...
Theoretical Description of the Fission Process
Advanced theoretical methods and high-performance computers may finally unlock the secrets of nuclear fission, a fundamental nuclear decay that is of great relevance to society. In this work, we studied the phenomenon of spontaneous fission using the symmetry-unrestricted nuclear density functional theory (DFT). Our results show that many observed properties of fissioning nuclei can be explained in terms of pathways in multidimensional collective space corresponding to different geometries of fission products. From the calculated collective potential and collective mass, we estimated spontaneous fission half-lives, and good agreement with experimental data was found. We also predicted a new phenomenon of trimodal spontaneous fission for some transfermium isotopes. Our calculations demonstrate that fission barriers of excited superheavy nuclei vary rapidly with particle number, pointing to the importance of shell effects even at large excitation energies. The results are consistent with recent experiments where superheavy elements were created by bombarding an actinide target with 48-calcium; yet even at high excitation energies, sizable fission barriers remained. Not only does this reveal clues about the conditions for creating new elements, it also provides a wider context for understanding other types of fission. Understanding of the fission process is crucial for many areas of science and technology. Fission governs existence of many transuranium elements, including the predicted long-lived superheavy species. In nuclear astrophysics, fission influences the formation of heavy elements on the final stages of the r-process in a very high neutron density environment. Fission applications are numerous. Improved understanding of the fission process will enable scientists to enhance the safety and reliability of the nation's nuclear stockpile and nuclear reactors. The deployment of a fleet of safe and efficient advanced reactors, which will also minimize radiotoxic waste and be proliferation-resistant, is a goal for the advanced nuclear fuel cycles program. While in the past the design, construction, and operation of reactors were supported through empirical trials, this new phase in nuclear energy production is expected to heavily rely on advanced modeling and simulation capabilities.
Witold Nazarewicz
Improved Calculation of Thermal Fission Energy
Thermal fission energy is one of the basic parameters needed in the calculation of antineutrino flux for reactor neutrino experiments. It is useful to improve the precision of the thermal fission energy calculation for current and future reactor neutrino experiments, which are aimed at more precise determination of neutrino oscillation parameters. In this article, we give new values for thermal fission energies of some common thermal reactor fuel iso-topes, with improvements on two aspects. One is more recent input data acquired from updated nuclear databases. The other, which is unprecedented, is a consideration of the production yields of fission fragments from both thermal and fast incident neutrons for each of the four main fuel isotopes. The change in calculated antineutrino flux due to the new values of thermal fission energy is about 0.33%, and the uncertainties of the new values are about 30% smaller.
Ma, X B; Wang, L Z; Chen, Y X; Cao, J
Los Alamos National Laboratory Fission Basis
This report is an overview of two main publications that provide a comprehensive review of the Los Alamos National Laboratory (LANL) Fission Basis. The first is the experimental paper, {sup F}ission Product Data Measured at Los Alamos for Fission Spectrum and Thermal Neutrons on {sup 239}Pu, {sup 235}U, {sup 238}U, [Selby, H. D., et al., Nucl. Data Sheets, Vol. 111 2010, pp. 2891-2922] and the second is the theoretical paper, Fission Product Yields from Fission Spectrum n+ {sup 239}Pu for ENDF/B-VII.1, [Chadwick, M. B., et al., Nucl. Data Sheets, Vol. 111, 2010, pp. 2923-2964]. One important note is that none of this work would have been possible without the great documentation of the experimental details and results by G.W. Knobeloch, G. Butler, C.I. Browne, B. Erdal, B. Bayhurst, R. Prestwood, V. Armijo, J. Hasty and many others. (authors)
Keksis, A.L.; Chadwick, M.B.; Selby, H.D.; Mac Innes, M.R.; Barr, D.W.; Meade, R.A.; Burns, C.J.; Wallstrom, T.C. [Los Alamos National Laboratory, NM 87545 (United States)
Systems analyses of fusion-driven fission
Fusion-driven fissioning systems possess unique advantages not available in either pure fusion or pure fission systems. These systems can set a reasonably low maximum price for fissionable fuel, prevent the necessity of mining low-grade uranium ores, and possibly lead to the best way to exploit the vast fuel potential of our depleted uranium reserves. These systems are less demanding on the characteristics of the fusion systems making the advanced fusion fuels more accessible. By relieving the fission lattice of the need for criticality, more attractive fission system characteristics are allowed. Accurate economic predictions are not yet possible due to continuing uncertainty about the transport properties of reactor-grade plasmas. Hybrid systems have the potential to avoid the causes of most of the criticisms of nuclear power.
Mills, R.G.
Fission Matrix Capability for MCNP Monte Carlo
In a Monte Carlo criticality calculation, before the tallying of quantities can begin, a converged fission source (the fundamental eigenvector of the fission kernel) is required. Tallies of interest may include powers, absorption rates, leakage rates, or the multiplication factor (the fundamental eigenvalue of the fission kernel, k{sub eff}). Just as in the power iteration method of linear algebra, if the dominance ratio (the ratio of the first and zeroth eigenvalues) is high, many iterations of neutron history simulations are required to isolate the fundamental mode of the problem. Optically large systems have large dominance ratios, and systems containing poor neutron communication between regions are also slow to converge. The fission matrix method, implemented into MCNP[1], addresses these problems. When Monte Carlo random walk from a source is executed, the fission kernel is stochastically applied to the source. Random numbers are used for: distances to collision, reaction types, scattering physics, fission reactions, etc. This method is used because the fission kernel is a complex, 7-dimensional operator that is not explicitly known. Deterministic methods use approximations/discretization in energy, space, and direction to the kernel. Consequently, they are faster. Monte Carlo directly simulates the physics, which necessitates the use of random sampling. Because of this statistical noise, common convergence acceleration methods used in deterministic methods do not work. In the fission matrix method, we are using the random walk information not only to build the next-iteration fission source, but also a spatially-averaged fission kernel. Just like in deterministic methods, this involves approximation and discretization. The approximation is the tallying of the spatially-discretized fission kernel with an incorrect fission source. We address this by making the spatial mesh fine enough that this error is negligible. As a consequence of discretization we get a spatially low-order kernel, the fundamental eigenvector of which should converge faster than that of continuous kernel. We can then redistribute the fission bank to match the fundamental fission matrix eigenvector, effectively eliminating all higher modes. For all computations here biasing is not used, with the intention of comparing the unaltered, conventional Monte Carlo process with the fission matrix results. The source convergence of standard Monte Carlo criticality calculations are, to some extent, always subject to the characteristics of the problem. This method seeks to partially eliminate this problem-dependence by directly calculating the spatial coupling. The primary cost of this, which has prevented widespread use since its inception [2,3,4], is the extra storage required. To account for the coupling of all N spatial regions to every other region requires storing N{sup 2} values. For realistic problems, where a fine resolution is required for the suppression of discretization error, the storage becomes inordinate. Two factors lead to a renewed interest here: the larger memory available on modern computers and the development of a better storage scheme based on physical intuition. When the distance between source and fission events is short compared with the size of the entire system, saving memory by accounting for only local coupling introduces little extra error. We can gain other information from directly tallying the fission kernel: higher eigenmodes and eigenvalues. Conventional Monte Carlo cannot calculate this data - here we have a way to get new information for multiplying systems. In Ref. [5], higher mode eigenfunctions are analyzed for a three-region 1-dimensional problem and 2-dimensional homogenous problem. We analyze higher modes for more realistic problems. There is also the question of practical use of this information; here we examine a way of using eigenmode information to address the negative confidence interval bias due to inter-cycle correlation. We apply this method mainly to four problems: 2D pressurized water reactor (PWR) [6],
Carney, Sean E. [Los Alamos National Laboratory; Brown, Forrest B. [Los Alamos National Laboratory; Kiedrowski, Brian C. [Los Alamos National Laboratory; Martin, William R. [Los Alamos National Laboratory
Future challenges for nuclear data research in fission (u)
I describe some high priority research areas in nuclear fission, where applications in nuclear reactor technologies and in modeling criticality in general are demanding higher accuracies in our databases. We focus on fission cross sections, fission neutron spectra, and fission product data.
Chadwick, Mark B [Los Alamos National Laboratory
Storm Track Dynamics
This paper reviews the current state of observational, theoretical, and modeling knowledge of the midlatitude storm tracks of the Northern Hemisphere cool season.
Edmund K. M. Chang; Sukyoung Lee; Kyle L. Swanson
Calculations of fission rates for r-process nucleosynthesis
Fission plays an important role in the r-process which is responsible not only for the yields of transuranium isotopes, but may have a strong influence on the formation of the majority of heavy nuclei due to fission recycling. We present calculations of beta-delayed and neutron-induced fission rates, taking into account different fission barriers predictions and mass formulae. It is shown that an increase of fission barriers results naturally in a reduction of fission rates, but that nevertheless fission leads to the termination of the r-process. Furthermore, it is discussed that the probability of triple fission could be high for $A>260$ and have an effect on the formation of the abundances of heavy nuclei. Fission after beta-delayed neutron emission is discussed as well as different aspects of the influence of fission upon r-process calculations.
I. V. Panov; E. Kolbe; B. Pfeiffer; T. Rauscher; K. -L. Kratz; F. -K. Thielemann
Fission Barriers of Compound Superheavy Nuclei
The dependence of fission barriers on the excitation energy of the compound nucleus impacts the survival probability of superheavy nuclei synthesized in heavy-ion fusion reactions. In this work, we investigate the isentropic ...
Sheikh, J. A.
Microscopic description of complex nuclear decay: multimodal fission
Our understanding of nuclear fission, a fundamental nuclear decay, is still incomplete due to the complexity of the process. In this paper, we describe a study of spontaneous fission using the symmetry-unrestricted nuclear density functional theory. Our results show that the observed bimodal fission can be explained in terms of pathways in multidimensional collective space corresponding to different geometries of fission products. We also predict a new phenomenon of trimodal spontaneous fission for some rutherfordium, seaborgium, and hassium isotopes.
A. Staszczak; A. Baran; J. Dobaczewski; W. Nazarewicz
Bimodal fission in the Skyrme-Hartree-Fock approach ?
studied within the Skyrme-Hartree-Fock+BCS framework. In the particlehole channel we take the Skyrme SkM ? effective force, while in the particleparticle channel we employ the seniority pairing interaction. Three static fission paths for all investigated heavy fermium isotopes are found. The analysis of these fission modes allows to describe observed asymmetric fission of 256 Fm, as well as bimodal fission of 258 Fm and symmetric fission in
A. Staszczak A; J. Dobaczewski B; W. Nazarewicz B
MCNP6 Fission Multiplicity with FMULT Card
With the merger of MCNPX and MCNP5 into MCNP6, MCNP6 now provides all the capabilities of both codes allowing the user to access all the fission multiplicity data sets. Detailed in this paper is: (1) the new FMULT card capabilities for accessing these different data sets; (2) benchmark calculations, as compared to experiment, detailing the results of selecting these separate data sets for thermal neutron induced fission on U-235.
Wilcox, Trevor [Los Alamos National Laboratory; Fensin, Michael Lorne [Los Alamos National Laboratory; Hendricks, John S. [Los Alamos National Laboratory; James, Michael R. [Los Alamos National Laboratory; McKinney, Gregg W. [Los Alamos National Laboratory
Transport properties of fission product vapors
Kinetic theory of gases is used to calculate the transport properties of fission product vapors in a steam and hydrogen environment. Provided in tabular form is diffusivity of steam and hydrogen, viscosity and thermal conductivity of the gaseous mixture, and diffusivity of cesium iodide, cesium hydroxide, diatomic tellurium and tellurium dioxide. These transport properties are required in determining the thermal-hydraulics of and fission product transport in light water reactors.
Im, K.H.; Ahluwalia, R.K.
Our 50-year odyssey with fission: Summary
On the occasion of this International Conference on Fifty Years Research in Nuclear Fission, we summarize our present understanding of the fission process and the challenges that lie ahead. The basic properties of fission arise from a delicate competition between disruptive Coulomb forces, cohesive nuclear forces, and fluctuating shell and pairing forces. These static forces are primarily responsible for such experimental phenomena as deformed ground-state nuclear shapes, fission into fragments of unequal size, sawtooth neutron yields, spontaneously fissioning isomers, broad resonances and narrow intermediate structure in fission cross sections, and cluster radioactivity. However, inertial and dissipative forces also play decisive roles in the dynamical evolution of a fissioning nucleus. The energy dissipated between the saddle and scission points is small for low initial excitation energy at the saddle point and increases with increasing excitation energy. At moderate excitation energies, the dissipation of collective energy into internal single-particle excitation energy proceeds largely through the interaction of nucleons with the mean field and with each other in the vicinity of the nuclear surface, as well as through the transfer of nucleons between the two portions of the evolving dumbell-like system. These unique dissipation mechanisms arise from the Pauli exclusion principle for fermions and the details of the nucleon-nucleon interaction, which make the mean free path of a nucleon near the Fermi surface at low excitation energy longer than the nuclear radius. With its inverse process of heavy-ion fusion reactions, fission continues to yield surprises in the study of large-amplitude collective nuclear motion. 87 refs., 12 figs.
Nix, J.R.
Overview of tritium fast-fission yields
Tritium production rates are very important to the development of fast reactors because tritium may be produced at a greater rate in fast reactors than in light water reactors. This report focuses on tritium production and does not evaluate the transport and eventual release of the tritium in a fast reactor system. However, if an order-of-magnitude increase in fast fission yields for tritium is confirmed, fission will become the dominant production source of tritium in fast reactors.
Tanner, J.E.
Modeling Fission Product Sorption in Graphite Structures
The goal of this project is to determine changes in adsorption and desorption of fission products to/from nuclear-grade graphite in response to a changing chemical environment. First, the project team will employ principle calculations and thermodynamic analysis to predict stability of fission products on graphite in the presence of structural defects commonly observed in very high- temperature reactor (VHTR) graphites. Desorption rates will be determined as a function of partial pressure of oxygen and iodine, relative humidity, and temperature. They will then carry out experimental characterization to determine the statistical distribution of structural features. This structural information will yield distributions of binding sites to be used as an input for a sorption model. Sorption isotherms calculated under this project will contribute to understanding of the physical bases of the source terms that are used in higher-level codes that model fission product transport and retention in graphite. The project will include the following tasks: Perform structural characterization of the VHTR graphite to determine crystallographic phases, defect structures and their distribution, volume fraction of coke, and amount of sp2 versus sp3 bonding. This information will be used as guidance for ab initio modeling and as input for sorptivity models; Perform ab initio calculations of binding energies to determine stability of fission products on the different sorption sites present in nuclear graphite microstructures. The project will use density functional theory (DFT) methods to calculate binding energies in vacuum and in oxidizing environments. The team will also calculate stability of iodine complexes with fission products on graphite sorption sites; Model graphite sorption isotherms to quantify concentration of fission products in graphite. The binding energies will be combined with a Langmuir isotherm statistical model to predict the sorbed concentration of fission products on each type of graphite site. The model will include multiple simultaneous adsorbing species, which will allow for competitive adsorption effects between different fission product species and O and OH (for modeling accident conditions).
Szlufarska, Izabela [University of Wisconsin, Madison, WI (United States); Morgan, Dane [University of Wisconsin, Madison, WI (United States); Allen, Todd [University of Wisconsin, Madison, WI (United States)
Accurate fission data for nuclear safety
The Accurate fission data for nuclear safety (AlFONS) project aims at high precision measurements of fission yields, using the renewed IGISOL mass separator facility in combination with a new high current light ion cyclotron at the University of Jyvaskyla. The 30 MeV proton beam will be used to create fast and thermal neutron spectra for the study of neutron induced fission yields. Thanks to a series of mass separating elements, culminating with the JYFLTRAP Penning trap, it is possible to achieve a mass resolving power in the order of a few hundred thousands. In this paper we present the experimental setup and the design of a neutron converter target for IGISOL. The goal is to have a flexible design. For studies of exotic nuclei far from stability a high neutron flux (10^12 neutrons/s) at energies 1 - 30 MeV is desired while for reactor applications neutron spectra that resembles those of thermal and fast nuclear reactors are preferred. It is also desirable to be able to produce (semi-)monoenergetic neutrons for benchmarking and to study the energy dependence of fission yields. The scientific program is extensive and is planed to start in 2013 with a measurement of isomeric yield ratios of proton induced fission in uranium. This will be followed by studies of independent yields of thermal and fast neutron induced fission of various actinides.
A. Solders; D. Gorelov; A. Jokinen; V. S. Kolhinen; M. Lantz; A. Mattera; H. Penttila; S. Pomp; V. Rakopoulos; S. Rinta-Antila
Spontaneous fission of the heaviest elements
Although spontaneous fission was discovered in /sup 238/U in 1940, detailed studies of the process were first made possible in the 1960's with the availability of milligram quantities of /sup 252/Cf. The advent of solid-state detectors made it possible to perform measurements of coincident fission fragments from even very short-lived spontaneous fission activities or those available in only very small quantities. Until 1971 it was believed that the main features of the mass and kinetic-energy distributions were essentially the same as those for thermal neutron-induced fission and that all low-energy fission proceeded via asymmetric mass division with total kinetic energies which could be derived by linear extrapolation from those of lighter elements. In 1971, measurements of /sup 257/Fm showed an increase in symmetric mass division with anomalously high TKE's. Subsequent experiments showed that in /sup 258/Fm and /sup 259/Fm, the most probable mass split was symmetric with very high total kinetic energy. Measurements for the heavier elements have shown symmetric mass distributions with both high and low total kinetic energies. Recent results for spontaneous fission properties of the heaviest elements are reviewed and compared with theory. 31 refs., 8 figs., 1 tab.
Hoffman, D.C.
Anatomy of neck configuration in fission decay
The anatomy of neck configuration in the fission decay of Uranium and Thorium isotopes is investigated in a microscopic study using Relativistic mean field theory. The study includes $^{236}U$ and $^{232}Th$ in the valley of stability and exotic neutron rich isotopes $^{250}U$, $^{256}U$, $^{260}U$, $^{240}Th$, $^{250}Th$, $^{256}Th$ likely to play important role in the r-process nucleosynthesis in stellar evolution. Following the static fission path, the neck configurations are generated and their composition in terms of the number of neutrons and protons are obtained showing the progressive rise in the neutron component with the increase of mass number. Strong correlation between the neutron multiplicity in the fission decay and the number of neutrons in the neck is seen. The maximum neutron-proton ratio is about 5 for $^{260}$U and $^{256}$Th suggestive of the break down of liquid-drop picture and inhibition of the fission decay in still heavier isotopes. Neck as precursor of a new mode of fission decay like multi-fragmentation fission may also be inferred from this study.
S. K. Patra; R. K. Choudhury; L. Satpathy
Spontaneous fission of /sup 259/Md
The mass and kinetic energy distributions of fission fragments from the spontaneous fission of th newly discovered nuclide /sup 259/Md were obtained. /sup 259/Md was identified as the E. C. daughter of /sup 259/No, and was found to decay entirely (> 95%) by spontaneous fission with a 95-min half-life. From the kinetic energies measured for 397 pairs of coincident fragments, a mass distribution was derived that is symmetric with sigma = 13 amu. /sup 259/Md, together with /sup 258/Fm and /sup 259/Fm, form a select group of three nuclides whose mass division in spontaneous fission is highly symmetric. Unlike the total-kinetic-energy (TKE) distributions of /sup 258/Fm and /sup 259/Fm, which peak at approx. = to 240 MeV, this distribution for /sup 259/Md is broad and is 50 MeV lower in energy. Analysis of the mass and energy distributions shows that events near mass symmetry also exhibit a broad TKE distribution, with one-third of the symmetric events having TKEs less than 200 MeV. The associated of low TKEs with symmetric mass division in the fission of very heavy actinides is anomalous and inconsistent with theories based upon the emergence of fragment shells near the scission point. Either three-body fragmentation or peculiar fragment shapes are assumed as the cause for the large consumption of Coulomb energy observed for a significant fraction of symmetric fissions in /sup 259/Md. 6 figures.
Hulet, E.K.; Wild, J.F.; Lougheed, R.W.; Baisden, P.A.; Landrum, J.H.; Dougan, R.J.; Mustafa, M.; Ghiorso, A.; Nitschke, J.M.
Thermal fission energy is one of the basic parameters needed in the calculation of antineutrino flux for reactor neutrino experiments. It is useful to improve the precision of the thermal fission energy calculation for current and future reactor neutrino experiments, which are aimed at more precise determination of neutrino oscillation parameters. In this article, we give new values for thermal fission energies of some common thermal reactor fuel isotopes, with improvements on three aspects. One is more recent input data acquired from updated nuclear databases. the second one is a consideration of the production yields of fission fragments from both thermal and fast incident neutrons for each of the four main fuel isotopes. The last one is more carefully calculation of the average energy taken away by antineutrinos in thermal fission with the comparison of antineutrino spectrum from different models. The change in calculated antineutrino flux due to the new values of thermal fission energy is about 0.32%, and the uncertainties of the new values are about 50% smaller.
X. B. Ma; W. L. Zhong; L. Z. Wang; Y. X. Chen; J. Cao
Tropical Cyclone Tracking Using a Neighbor Enclosed Area Tracking Algorithm
Tropical cyclone (TC) tracking is essential for calculating TC statistics from gridded datasets. A new method for TC tracking is presented here using neighbor enclosed area tracking (NEAT), which is based on the temporal overlap of enclosed areas ...
Yuya Satake; Masaru Inatsu; Masato Mori; Akira Hasegawa
Tropical cyclone tracking using a neighbor enclosed area tracking algorithm
Adaptive Constraints for Feature Tracking
In this paper extensions to an existing tracking algorithm are described. These extensions implement adaptive tracking constraints in the form of regional upper-bound displacements and an adaptive track smoothness constraint. Together, these ...
K. I. Hodges
Feature Tracking Using Reeb Graphs
H.W. , Wegner, R. : Volume tracking using higher dimensionalShen, H.W. : Ef?cient isosurface tracking using precomputedBell, J. : Analyzing and tracking burning structures in lean
Weber, Gunther H.
a simple GPU based particle tracking code, TracyGPU, isP U COMPUTING FOR PARTICLE TRACKING Hiroshi Nishimura, K a iCOMPUTING FOR PARTICLE TRACKING * Hiroshi Nishimura ', Kai
Nishimura, Hiroshi
Object tracking via uncertainty minimization
Color and texture provide important visual information for real-time tracking of non-rigid and partially occluded objects. Recent developments have shown the robustness and effectiveness of color based tracking algorithms, especially for tracking tasks ...
Albert Akhriev
Microscopic Description of Nuclear Fission: Fission Barrier Heights of Even-Even Actinides
We evaluate the performance of modern nuclear energy density functionals for predicting inner and outer fission barrier heights and energies of fission isomers of even-even actinides. For isomer energies and outer barrier heights, we find that the self-consistent theory at the HFB level is capable of providing quantitative agreement with empirical data.
J. McDonnell; N. Schunck; W. Nazarewicz
McDonnell, J; Nazarewicz, W
Ternary Fission of 249Cf(n,f) and 250Cf(SF)
+b. INTRODUCTION Nuclear fission is essentially a binaryternary fission data are of interest for nuclear physics innuclear reactors and also in used fuel elements due to spontaneous fission.
, S. Vermote
between heavy and light fission fragments is extended byenergies in actinides exceed the fission barrier height,so that prompt fission becomes possible,(l) The
Zhong-yu, Ma
Melodic Fission in Trance Music: The Perception of Interleaved Vocal and Non-Vocal Melodies
W. J. 1968. Rhythmic fission and perceptual organization. J. Dowling. "Rhythmic fission and perceptual organization," 2 (2003): 217-249. Melodic Fission in Trance Music sources
Atherton, Lawrence John
Effect of Angular Momentum on Fission Probability (Thesis),R. Vandenbosch, Nuclear Fission, to be published in Nuclearfrom Heavy-lon-Induced Fission (Thesis), Lawrence Radiation
Thomas, T. Darrah; Gordon, Glen E.; Latimer, Robert M.; Seaborg, Glenn T.
Physics and Chemistry of Fission, Vienna 1969 (IAEA, ViennaDeformation energies along the fission path plotted againstMICROSCOPIC CALCULATIONS OF FISSION BARRIERS AND CRITICAL
Diebel, Michael
INELASTIC PROCESSES AND IN FISSION L. G. Moretto Lawrenceinelastic processes and fission have been studied in thealpha [10] and sequential fission probabilities and angular
al. , in Proc. Sem. on Fission, Corsendonk, Belgium, Worldand neutron induced fission of Cm and Cf isotopes", Ph.D.emission probabilities (per fission) for the various ternary
German) The concepts of fission theory developed in previous works (Ann. Physik (7) 7, 333(1961)) are systematically developed. From the basic conception of shell structure dependent deformation of the fragments at the moment of their separation, magic effects result in the nuclear force potential between both fragments and the mean kinetic energy of the fragments whose interaction makes quantitatively comprehensible the observed fission asymmetry. The spontaneous fission of Cf/sup 252/ is discussed as an example. The symmetric fission of Bi/ sup 209/ (by deuterons) is described. A qualitative clarification is given of the known decrease in fission asymmetry with increased excitation energy on the basis of the general hypotheses developed. (tr-auth)
Brunner, W.; Paul, H.
Bimodal fission in the Skyrme-Hartree-Fock approach
Spontaneous-fission properties of 256Fm, 258Fm, and 260Fm isotopes are studied within the Skyrme-Hartree-Fock+BCS framework. In the particle-hole channel we take the Skyrme SkM* effective force, while in the particle-particle channel we employ the seniority pairing interaction. Three static fission paths for all investigated heavy fermium isotopes are found. The analysis of these fission modes allows to describe observed asymmetric fission of 256Fm, as well as bimodal fission of 258Fm and symmetric fission in 260Fm.
A. Staszczak; J. Dobaczewski; W. Nazarewicz
Manhattan Project: Fission Comes to America, 1939
Excerpt from the comic book "Adventures Inside the Atom." Click on this image or visit the "Library" to view the whole comic book. FISSION COMES TO AMERICA Excerpt from the comic book "Adventures Inside the Atom." Click on this image or visit the "Library" to view the whole comic book. FISSION COMES TO AMERICA (1939) Events > Atomic Discoveries, 1890s-1939 A Miniature Solar System, 1890s-1919 Exploring the Atom, 1919-1932 Atomic Bombardment, 1932-1938 The Discovery of Fission, 1938-1939 Fission Comes to America, 1939 News of the fission experiments of Otto Hahn and Fritz Strassmann, and of the Meitner-Frisch calculations that confirmed them, spread rapidly. Meitner and Frisch communicated their results to Niels Bohr, who was in Copenhagen preparing to depart for the United States via Sweden and England. Bohr confirmed the validity of the findings while sailing to New York City, arriving on January 16, 1939. Ten days later Bohr, accompanied by Enrico Fermi, communicated the latest developments to some European émigré scientists who had preceded him to this country and to members of the American scientific community at the opening session of a conference on theoretical physics in Washington, D.C.
Software Services: Tracking
Tracking Good project management is the cornerstone of any successful project. It help ensure delivery of a quality product that is on time and that meets its goals. To this end,...
Airborne Tracking Sunphotometer
An airborne tracking sunphotometer, mounted on the outside top surface of an aircraft has been developed to provide unrestricted viewing of the Sun. This instrument will substantially increase the data that scientists can gather for atmospheric ...
Tak Matsumoto; Philip Russell; Cesar Mina; William Van Ark; Victor Banta
Energy Tracking Software Platform
Acceleration has created an interactive energy tracking and visualization platform that supports decreasing electric, water, and gas usage. Homeowners have access to tools that allow them to gauge their use and track progress toward a smaller energy footprint. Real estate agents have access to consumption data, allowing for sharing a comparison with potential home buyers. Home builders have the opportunity to compare their neighborhood's energy efficiency with competitors. Home energy raters have a tool for gauging the progress of their clients after efficiency changes. And, social groups are able to help encourage members to reduce their energy bills and help their environment. EnergyIT.com is the business umbrella for all energy tracking solutions and is designed to provide information about our energy tracking software and promote sales. CompareAndConserve.com (Gainesville-Green.com) helps homeowners conserve energy through education and competition. ToolsForTenants.com helps renters factor energy usage into their housing decisions.
Ryan Davis; Nathan Bird; Rebecca Birx; Hal Knowles
Investigating the Libor Rate," mimeo. Abrantes-Metz, R. ,Libor data: Historial 1 month Libor rates, British Bankers1108R) Tracking the Libor Rate Rosa M. Abrantes-Metz , Sofia
Localization and Tracking
Abstract—Reliable obstacle detection and localization is a key issue for driver assistance systems, particularly in urban environments. In this study a multi-modal perception approach is investigated, the objective being to enhance vehicle localization and dynamic object tracking in a world-centric map. A 3D ego-localization is achieved by merging information from a stereo vision system and data obtained from vehicle sensors. Mobile objects are detected using a multi-layer lidar that is also used to identify a constrained search space within the multiple target tracking process. Object localization and tracking is then performed in the fixed frame, which facilitates analysis and understanding of the scene. Experimental results using real world data are performed to evaluate the performance of the multi-modal system, and these are presented to show the effectiveness of the approach. Index Terms—Multi-modal perception, visual odometry, object tracking, dynamic map, intelligent vehicles. I.
Sergio A. Rodríguez F; Vincent Frémont; Véronique Cherfaoui
Solar tracking system
This report describes an automated solar tracking system which is adaptable to most solar collectors which require alignment with the sun's radiation. The system uses partially shaded photovoltaic solar cells to produce error signals for both elevation and azimuth tracking with a high degree of accuracy. An electrical circuit processes the error signals and controls gearmotors to direct the solar collector toward the sun.
Hammons, B.E.
The dependence of fission barriers on the excitation energy of the compound nucleus impacts the survival probability of superheavy nuclei synthesized in heavy-ion fusion reactions. In this work, we investigate the isentropic fission barriers by means of the self-consistent nuclear density functional theory. The relationship between isothermal and isentropic descriptions is demonstrated. Calculations have been carried out for $^{264}$Fm, $^{272}$Ds, $^{278}$112, $^{292}$114, and $^{312}$124. For nuclei around $^{278}$112 produced in "cold fusion" reactions, we predict a more rapid decrease of fission barriers with excitation energy as compared to the nuclei around $^{292}$114 synthesized in "hot fusion" experiments. This is explained in terms of the difference between the ground-state and saddle-point temperatures. The effect of the particle gas is found to be negligible in the range of temperatures studied.
J. C. Pei; W. Nazarewicz; J. A. Sheikh; A. K. Kerman
BS>A method is described for fabricating a jacketed fissionable body or slug to provide an effective leak-proof seal between the jacket and the end closure. A housing for the fissionable slug is first formed and then tinned on the interior. The fissionable slug is coated on its exterior surface with the same material used to tin the interior of the housing. The coated slug is then inserted into the housing. A disc shaped end closure for the housing, coated with the tinning material, is inserted into the open end of the housing while the tinning material is still liquid. The end of the housing is then swaged into good contact with the periphery of the closure.
Young, G.J.; Ohlinger, L.A.
Low-mass fission detector for the fission neutron spectrum measurement
For the fission neutron spectrum measurement, the neutron energy is determined in a time-of-flight experiment by the time difference between the fission event and detection of the neutron. Therefore, the neutron energy resolution is directly determined by the time resolution of both neutron and fission detectors. For the fission detection, the detector needs not only a good timing response but also the tolerance of radiation damage and high {alpha}-decay rate. A parallel-plate avalanche counter (PPAC) has many advantages for the detection of heavy charged particles such as fission fragments. These include fast timing, resistance to radiation damage, and tolerance of high counting rate. A PPAC also can be tuned to be insensitive to particles, which is important for experiments with - emitting actinides. Therefore, a PPAC is an ideal detector for experiments requiring a fast and clean trigger for fission. In the following sections, the description will be given for the design and performance of a new low-mass PPAC for the fission-neutron spectrum measurements at LANL.
Wu, C Y; Henderson, R; Gostic, J; Haight, R C; Lee, H Y
Fusion-Fission of 16O+197Au at Sub-Barrier Energies
The recent discovery of heavy-ion fusion hindrance at far sub-barrier energies has focused much attention on both experimental and theoretical studies of this phenomenon. Most of the experimental evidence comes from medium-heavy systems such as Ni+Ni to Zr+Zr, for which the compound system decays primarily by charged-particle evaporation. In order to study heavier systems, it is, however, necessary to measure also the fraction of the decay that goes into fission fragments. In the present work we have, therefore, measured the fission cross section of 16O+197Au down to unprecedented far sub-barrier energies using a large position sensitive PPAC placed at backward angles. The preliminary cross sections will be discussed and compared to earlier studies at near-barrier energies. No conclusive evidence for sub-barrier hindrance was found, probably because the measurements were not extended to sufficiently low energies.
B. B. Back; C. L. Jiang; R. V. F. Janssens; D. J. Henderson; B. R. Shumard; C. J. Lister; D. Peterson; K. E. Rehm; I. Tanihata; X. Tang; X. Wang; S. Zhu
Italian hybrid and fission reactors scenario analysis
Italy is a country where a long tradition of studies both in the fission and fusion field is consolidated; nevertheless a strong public opinion concerned with the destination of the Spent Nuclear Fuel hinders the development of nuclear power. The possibility to a severe reduction of the NSF mass generated from a fleet of nuclear reactors employing an hypothetical fusionfission hybrid reactor has been investigated in the Italian framework. The possibility to produce nuclear fuel for the fission nuclear reactors with the hybrid reactor was analyzed too.
Ciotti, M.; Manzano, J.; Sepielli, M. [ENEA CR Frascati, Via Enrico Fermi, 45, 00044, Frascati, Roma (Italy); ENEA CR casaccia, Via Anguillarese, 301, 00123, Santa Maria di Galeria, Roma (Italy)
Reexamination of fission fragment angular distributions and the fission process: Formalism
The theory of fission fragment angular distributions is examined and the universally used expression is found to be valid only under restrictive assumptions. A more general angular distribution formula is derived and applied to recent data of high spin systems. At the same time it is shown that the strong anisotropies observed from such systems can be understood without changing the essential basis of standard fission theory. The effects of reaction mechanisms other than complete fusion on fission fragment angular distributions are discussed and possible angular distribution signatures of noncompound nucleus formation are mentioned.
Bond, P.D.
Fission-Suppressed Fusion, Thorium-Cycle Breeder and Nonproliferation
R. W. Moir
Optimally moderated nuclear fission reactor and fuel source therefor
An improved nuclear fission reactor of the continuous fueling type involves determining an asymptotic equilibrium state for the nuclear fission reactor and providing the reactor with a moderator-to-fuel ratio that is optimally moderated for the asymptotic equilibrium state of the nuclear fission reactor; the fuel-to-moderator ratio allowing the nuclear fission reactor to be substantially continuously operated in an optimally moderated state.
Ougouag, Abderrafi M. (Idaho Falls, ID); Terry, William K. (Shelley, ID); Gougar, Hans D. (Idaho Falls, ID)
Chemical States of Volatile and Corrosive Fission Products in ...
Page 1. Chemical States of Volatile and Corrosive Fission Products in Thorium Based Fuels from Thermodynamic Studies ...
Fission measurements with PPAC detectors using a coincidence technique
A fission detection setup based on Parallel Plate Avalanche Counters (PPAC) has been constructed and used at the CERN n-TOF facility. The setup takes advantage of the coincidence detection of both fission fragments to discriminate the background reactions produced by high energy neutrons and it allows obtaining neutron-induced fission cross section up to 1 GeV. (authors)
Paradela, C.; Duran, I.; Tarrio, D. [Universidad de Santiago de Compostela (Spain); Audouin, L.; Tassan-Got, L.; Stephan, C. [Inst. de Physique Nucleaire d'Orsay (France)
Prompt muon-induced fission: a sensitive probe for nuclear energy dissipation and fission dynamics
Following the formation of an excited muonic atom, inner shell transitions may proceed without photon emission by inverse internal conversion, i.e. the muonic excitation energy is transferred to the nucleus. In actinides, the 2p -> 1s and the 3d -> 1s muonic transitions result in excitation of the nuclear giant dipole and giant quadrupole resonances, respectively, which act as doorway states for fission. The nuclear excitation energy is typically 6.5 - 10 MeV. Because the muon lifetime is long compared to the timescale of prompt nuclear fission, the motion of the muon in the Coulomb field of the fissioning nucleus may be utilized to learn about the dynamics of fission.
Volker E. Oberacker; A. Sait Umar; Feodor F. Karpeshin
Liquid uranium alloy-helium fission reactor
This invention describes a nuclear fission reactor which has a core vessel and at least one tandem heat exchanger vessel coupled therewith across upper and lower passages to define a closed flow loop. Nuclear fuel such as a uranium alloy in its liquid phase fills these vessels and flow passages. Solid control elements in the reactor core vessel are adapted to be adjusted relative to one another to control fission reaction of the liquid fuel therein. Moderator elements in the other vessel and flow passages preclude fission reaction therein. An inert gas such as helium is bubbled upwardly through the heat exchanger vessel operable to move the liquid fuel upwardly therein and unidirectionally around the closed loop and downwardly through the core vessel. This helium gas is further directed to heat conversion means outside of the reactor vessels to utilize the heat from the fission reaction to generate useful output. The nuclear fuel operates in the 1200 to 1800/sup 0/C range, and even higher to 2500/sup 0/C.
Minkov, V.
Fission Detection Using the Associated Particle Technique
A beam of tagged 14 MeV neutrons from the deuterium-tritium (DT) reaction is used to induce fission in a target composed of depleted uranium. The generator yield is 107 neutrons/second radiated into a 4? solid angle. Two 4 in.×4 in. NaI detectors are used for gamma-ray detection. The fission process is known to produce multiple gamma-rays and neutrons. Triple coincidences (?-?-?) are measured as a function of neutron flight time up to 90 ns after fission, where the ?-particle arises from the DT reaction. A sudden increase in the triple coincidence rate at the location of the material is used to localize and detect fission in the interrogated target. Comparisons are made with experiment runs where lead, tungsten, and iron were used as target materials. The triple coincidence response profile from depleted uranium is noted to be different to those observed from the other target materials. The response from interrogation targets composed of fissile material is anticipated to be even more unique than that observed from depleted uranium.
R.P. Keegan, J.P. Hurley, J.R. Tinsley, R. Trainham, S.C. Wilde
Density Functional Theory Approach to Nuclear Fission
The Skyrme nuclear energy density functional theory (DFT) is used to model neutron-induced fission in actinides. This paper focuses on the numerical implementation of the theory. In particular, it reports recent advances in DFT code development on leadership class computers, and presents a detailed analysis of the numerical accuracy of DFT solvers for near-scission calculations.
This invention teaches a nuclear fission reactor having a core vessel and at least one tandem heat exchanger vessel coupled therewith across upper and lower passages to define a closed flow loop. Nuclear fuel such as a uranium alloy in its liquid phase fills these vessels and flow passages. Solid control elements in the reactor core vessel are adapted to be adjusted relative to one another to control fission reaction of the liquid fuel therein. Moderator elements in the other vessel and flow passages preclude fission reaction therein. An inert gas such as helium is bubbled upwardly through the heat exchanger vessel operable to move the liquid fuel upwardly therein and unidirectionally around the closed loop and downwardly through the core vessel. This helium gas is further directed to heat conversion means outside of the reactor vessels to utilize the heat from the fission reaction to generate useful output. The nuclear fuel operates in the 1200.degree.-1800.degree. C. range, and even higher to 2500.degree. C., limited only by the thermal effectiveness of the structural materials, increasing the efficiency of power generation from the normal 30-35% with 300.degree.-500.degree. C. upper limit temperature to 50-65%. Irradiation of the circulating liquid fuel, as contrasted to only localized irradiation of a solid fuel, provides improved fuel utilization.
Minkov, Vladimir (Skokie, IL)
Improving MPI communication via data type fission
Message Passing Interface (MPI) messages are centered around transmitting instances of MPI data types. The data types represented in MPI terms are usually modeled after data types native to the application. If a user does not want to transmit a field ... Keywords: MPI, communication, data type fission, static transformation
Ben Perry; Martin Swany
One step of a process for separating plutonium from uranium and fission products is presented. A nitric acid solution containing these constituents is treated with formic acid to reduce simultaneously the plutonium to a valence state of not greater than +4 and destroy and eliminate the excess nitric acid.
Olson, C.M.
Reactor power history from fission product signatures
The purpose of this research was to identify fission product signatures that could be used to uniquely identify a specific spent fuel assembly in order to improve international safeguards. This capability would help prevent and deter potential diversion of spent fuel for a nuclear weapons program. The power history experienced by a fuel assembly is distinct and could serve as the basis of a method for unique identification. Using fission product concentrations to characterize the assembly power history would limit the ability of a proliferator to deceive the identification method. As part of the work completed, the TransLat lattice physics code was successfully benchmarked for fuel depletion. By developing analytical models for potential monitor isotopes an understanding was built of how specific isotope characteristics affect the production and destruction mechanisms that determine fission product concentration. With this knowledge potential monitor isotopes were selected and tested for concentration differences as a result of power history variations. Signature ratios were found to have significant concentration differences as a result of power history variations while maintaining a constant final burnup. A conceptual method for implementation of a fission product identification system was proposed in conclusion.
Sweeney, David J.
Following the formation of an excited muonic atom, inner shell transitions may proceed without photon emission by inverse internal conversion, i.e. the muonic excitation energy is transferred to the nucleus. In actinides, the 2p ? 1s and the 3d ? 1s muonic transitions result in excitation of the nuclear giant dipole and giant quadrupole resonances, respectively, which act as doorway states for fission. The nuclear excitation energy is typically 6.5 ? 10 MeV. Because the muon lifetime is long compared to the timescale of prompt nuclear fission, the motion of the muon in the Coulomb field of the fissioning nucleus may be utilized to learn about the dynamics of fission. If there is large friction between the outer fission barrier and the scission point the muon will remain in the lowest molecular energy level and emerge in the 1s bound state of the heavy fission fragment. On the other hand, if friction is small (i.e. the nuclear collective motion is fast) there is a nonvanishing probability that the muon may be promoted to higher-lying molecular orbitals, e.g. the 2p? level, from where
Induction of nuclear fission by high-voltage application
In nuclear power generation, fissile materials are mainly used. For example, $U^{235}$ is fissile and therefore quite essential for use of nuclear energy. However, the material $U^{235}$ has very small natural abundance less than 1 %. We should seek possibility of utilizing fissionable materials such as $U^{238}$ because natural abundance of such fissionable materials is generally much larger than fissile ones. In this paper, we show that thermal neutrons with vanishing kinetic energy can induce nuclear fission when high voltage is applied to fissionable materials. To obtain this result, we use the liquid-drop model for nuclei. Finally, we propose how fissionable materials can be utilized.
Hirokazu Maruyama
Transient effects in fission evidenced from new experimental signatures
A new experimental approach is introduced to investigate the relaxation of the nuclear deformation degrees of freedom. Highly excited fissioning systems with compact shapes and low angular momenta are produced in peripheral relativistic heavy-ion collisions. Both fission fragments are identified in atomic number. Fission cross sections and fission-fragment element distributions are determined as a function of the fissioning element. From the comparison of these new observables with a nuclear-reaction code a value for the transient time is deduced.
B. Jurado; C. Schmitt; K. -H. Schmidt; J. Benlliure; T. Enqvist; A. R. Junghans; A. Kelic; F. Rejmund
Theory of nuclear fission: present status and prospects
General properties of nuclear fission are reviewed and related to our present knowledge of fission theory. For this purpose the basic reasons for the shape of the fission barriers are discussed and their consequences compared with experimental results on barrier shapes and structures. Special emphasis is put on the asymmetry of the fission barriers and mass-distributions and its relation to the shells of the nascent fragment clusters. Finally the problem of a dynamical description of fission and its relation to the question of viscosity is discussed. (auth)
Mosel, U.; Goldberg, D.A.; Marion, J.B.; Wallace, S.J. (eds.)
Fission Yield Measurements by Inductively Coupled Plasma Mass-Spectrometry
Correct prediction of the fission products inventory in irradiated nuclear fuels is essential for accurate estimation of fuel burnup, establishing proper requirements for spent fuel transportation and storage, materials accountability and nuclear forensics. Such prediction is impossible without accurate knowledge of neutron induced fission yields. Unfortunately, the accuracy of the fission yields reported in the ENDF/B-VII.0 library is not uniform across all of the data and much of the improvement is desired for certain isotopes and fission products. We discuss our measurements of cumulative fission yields in nuclear fuels irradiated in thermal and fast reactor spectra using Inductively Coupled Plasma Mass Spectrometry.
Irina Glagolenko; Bruce Hilton; Jeffrey Giglio; Daniel Cummings; Karl Grimm; Richard McKnight
Fifty years of nuclear fission: Nuclear data and measurements series
This report is the written version of a colloquium first presented at Argonne National Laboratory in January 1989. The paper begins with an historical preamble about the events leading to the discovery of nuclear fission. This leads naturally to an account of early results and understanding of the fission phenomena. Some of the key concepts in the development of fission theory are then discussed. The main theme of this discussion is the topography of the fission barrier, in which the interplay of the liquid-drop model and nucleon shell effects lead to a wide range of fascinating phenomena encompassing metastable isomers, intermediate-structure effects in fission cross-sections, and large changes in fission product properties. It is shown how study of these changing effects and theoretical calculations of the potential energy of the deformed nucleus have led to broad qualitative understanding of the nature of the fission process. 54 refs., 35 figs.
Tracks in the Snow
Tracks in the Snow Tracks in the Snow Nature Bulletin No. 98 January 11, 1947 Forest Preserve District of Cook County William N. Erickson, President Roberts Mann, Superintendent of Conservation TRACKS IN THE SNOW Tracks in the snow tell fascinating stories of the secret lives of the wild animals that are abroad in wintertime -- stories of their search for food and the never-ending warfare between the hunter and the hunted. Walking through the woods, we came upon the trail of a red fox. The footprints of a fox are more pointed than those of a dog, more nearly in a straight line, and the hind foot is placed exactly on the print of the corresponding front foot. More-over, this fox had walked out across a meadow to a big ant hill on top of which he sat to listen and test the wind for scent. A dog will not do that. Later, back in the woods, he had jumped on a fallen tree and trotted along its length. A dog will not do that, either. The fox was traveling leisurely, pausing here and there to sniff at tufts of grass and other possible hiding places for mice.
Spiral track oven
Final report on development of a continuously operating oven system in which the parts are progressing automatically on a spiral track for in-line service installation for the production of electronic and/or other components to be heat cured or dried.
Drobilisch, Sandor
Tracking highly maneuverable targets with unknown behavior
for maneuvering target tracking," IEEE Trans. Aerosp.converted measurements for tracking," IEEE Trans. Aerosp.particle filters for tracking a maneuvering target," in
Schell, C; Linder, S P; Zeidler, J R
Tracking multiple mice through severe occlusions
A Mathematical Formulation of Tracking . . . 2.1 De?ning theBased Tracking . . . . . . . . . . . . . . . . . . . . 6.8.2Segmentation . . . . . . . . . Edge-Based Tracking . . . . .
Branson, Kristin
Experiments with Underwater Robot Localization and Tracking
pipeline-, and ?sh tracking," Journal of Marine Design andRobot Localization and Tracking Peter Corke † , Carrickinvestigation into feature tracking for visual odometry for
Corke, Peter; Detwiler, Carrick; Dunbabin, Matthew; Hamilton, Michael; Rus, Daniela; Vasilescu, Iuliu
Storm Tracks and Climate Change
Extratropical and tropical transient storm tracks are investigated from the perspective of feature tracking in the ECHAM5 coupled climate model for the current and a future climate scenario. The atmosphere-only part of the model, forced by ...
Lennart Bengtsson; Kevin I. Hodges; Erich Roeckner
Fusion-fission energy systems evaluation
This report serves as the basis for comparing the fusion-fission (hybrid) energy system concept with other advanced technology fissile fuel breeding concepts evaluated in the Nonproliferation Alternative Systems Assessment Program (NASAP). As such, much of the information and data provided herein is in a form that meets the NASAP data requirements. Since the hybrid concept has not been studied as extensively as many of the other fission concepts being examined in NASAP, the provided data and information are sparse relative to these more developed concepts. Nevertheless, this report is intended to provide a perspective on hybrids and to summarize the findings of the rather limited analyses made to date on this concept.
Teofilo, V.L.; Aase, D.T.; Bickford, W.E.
Phase Transition Induced Fission in Lipid Vesicles
In this work we demonstrate how the first order phase transition in giant unilamellar vesicles (GUVs) can function as a trigger for membrane fission. When driven through their gel-fluid phase transition GUVs exhibit budding or pearl formation. These buds remain connected to the mother vesicle presumably by a small neck. Cooling these vesicles from the fluid phase (T>Tm) through the phase transition into the gel state (Tfission of the neck, while the mother vesicle remains intact. Pearling tubes which formed upon heating break-up and decay into multiple individual vesicles which then diffuse freely. Finally we demonstrate that mimicking the intracellular bulk viscosity by increasing the bulk viscosity to 40cP does not affect the overall fission process, but leads to a significant decrease in size of the released vesicles.
C. Leirer; B. Wunderlich; V. M. Myles; M. F. Schneider
Final excitation energy of fission fragments
We study how the excitation energy of the fully accelerated fission fragments is built up. It is stressed that only the intrinsic excitation energy available before scission can be exchanged between the fission fragments to achieve thermal equilibrium. This is in contradiction with most models used to calculate prompt neutron emission where it is assumed that the total excitation energy of the final fragments is shared between the fragments by the condition of equal temperatures. We also study the intrinsic excitation-energy partition according to a level density description with a transition from a constant-temperature regime to a Fermi-gas regime. Complete or partial excitation-energy sorting is found at energies well above the transition energy.
Karl-Heinz Schmidt; Beatriz Jurado
Fission of a multiphase membrane tube
A common mechanism for intracellular transport is the use of controlled deformations of the membrane to create spherical or tubular buds. While the basic physical properties of homogeneous membranes are relatively well-known, the effects of inhomogeneities within membranes are very much an active field of study. Membrane domains enriched in certain lipids in particular are attracting much attention, and in this Letter we investigate the effect of such domains on the shape and fate of membrane tubes. Recent experiments have demonstrated that forced lipid phase separation can trigger tube fission, and we demonstrate how this can be understood purely from the difference in elastic constants between the domains. Moreover, the proposed model predicts timescales for fission that agree well with experimental findings.
Jean-Marc Allain; Cornelis Storm; Aurelien Roux; Martine Ben Amar; Jean-Francois Joanny
Fusion-Fission of 16 O+ 197 Au at Sub-Barrier Energies
Abstract. The recent discovery of heavy-ion fusion hindrance at far sub-barrier energies has focused much attention on both experimental and theoretical studies of this phenomenon. Most of the experimental evidence comes from medium-heavy systems such as Ni+Ni to Zr+Zr, for which the compound system decays primarily by charged-particle evaporation. In order to study heavier systems, it is, however, necessary to measure also the fraction of the decay that goes into fission fragments. In the present work we have, therefore, measured the fission cross section of 16 O+ 197 Au down to unprecedented far sub-barrier energies using a large position sensitive PPAC placed at backward angles. The preliminary cross sections will be discussed and compared to earlier studies at near-barrier energies. No conclusive evidence for sub-barrier hindrance was found, probably because the measurements were not extended to sufficiently low energies. Keywords: Heavy-ion fusion, fission, cross section,S-factor PACS: 24.10.Eq, 25.70.Jj, 26.30.+k
B. B. Back A; C. L. Jiang A; R. V. F. Janssens A; D. J. Henderson A; B. R. Shumard A; C. J. Lister A; D. Peterson A; K. E. Rehm A; I. Tanihata A; X. Tang A; X. Wang A; S. Zhu A
Lesson 5- Fission and Chain Reactions
Energy.gov (U.S. Department of Energy (DOE))
Lesson Four showed how the nuclei of atoms store energy and how unstable atoms decay and release energy. How do nuclear engineers use this knowledge to help them harness energy to make electricity? The answer lies in being able to start a nuclear chain reaction in fuel inside a nuclear power plant and keep it going. This lesson examines nuclear reactions called fission as well as how uranium is processed from ore to fuel.
A process is given for precipitating fission products from a body of water having a pH of above 6.5. Calcium permanganate and ferrous sulfate are added in a molar ratio of l: 3, whereby a mixed precipitate of manganese dioxide, ferric hydroxide and calcium sulfate is formed; the precipitate carries the fisston products and settles to the bottom of the body of water. (AEC)
Rosinski, J.
Undergraduate Measurements For Fission Reactor Applications
Undergraduate students at the University of Dallas (UD) have investigated elastic and inelastic neutron scattering cross sections on structural materials important for criticality considerations in nuclear fission processes. Neutrons scattered off of {sup 23}Na and {sup Nat}Fe were detected using neutron time-of-flight techniques at the University of Kentucky Low-Energy Nuclear Accelerator Facility. These measurements are part of an effort to increase the efficiency of power generation from existing fission reactors in the US and in the design of new fission systems. Students have learned the basics of how to operate the Model CN Van de Graaff generator at the laboratory, setup detectors and electronics, use data acquisition systems, and they are currently analyzing the angular dependence of the scattered neutrons for incident neutron energies of 3.57 and 3.80 MeV. Most students participating in the project will use the research experience as the material for their undergraduate research thesis required for all Bachelor of Science students at the University of Dallas. The first student projects on this topic were completed during the summer of 2010; an overview of student participation in this investigation and their preliminary results will be presented.
Hicks, S. F.; Kersting, L. J.; Lueck, C. J.; McDonough, P. [Department of Physics, University of Dallas, Irving TX 75019 (United States); Crider, B. P.; McEllistrem, M. T.; Peters, E. E. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Vanhoy, J. R. [Department of Physics, United States Naval Academy, Annapolis MD 21402 (United States)
Pennsylvania Source Term Tracking System
The Pennsylvania Source Term Tracking System tabulates surveys received from radioactive waste generators in the Commonwealth of radioactive waste is collected each quarter from generators using the Low-Level Radioactive Waste Management Quarterly Report Form (hereafter called the survey) and then entered into the tracking system data base. This personal computer-based tracking system can generate 12 types of tracking reports. The first four sections of this reference manual supply complete instructions for installing and setting up the tracking system on a PC. Section 5 presents instructions for entering quarterly survey data, and Section 6 discusses generating reports. The appendix includes samples of each report.
SOFTWARE QUALITY & SYSTEMS ENGINEERING PROGRAM: Project Tracking...
SOFTWARE QUALITY & SYSTEMS ENGINEERING PROGRAM: Project Tracking Checklist SOFTWARE QUALITY & SYSTEMS ENGINEERING PROGRAM: Project Tracking Checklist The following checklist is...
Technology Tracking Reports - Solid-State Lighting
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Electron-capture delayed fission properties of 244Es
Electron-capture delayed fission was observed in {sup 244}Es produced via the {sup 237}Np({sup 12}C,5n){sup 244}Es reaction at 81 MeV (on target) with a production cross section of 0.31{+-}0.12 {micro}b. The mass-yield distribution of the fission fragments is highly asymmetric. The average preneutron-emission total kinetic energy of the fragments was measured to be 186{+-}19 MeV. Based on the ratio of the number of fission events to the measured number of {alpha} decays from the electron-capture daughter {sup 244}Cf (100% {alpha} branch), the probability of delayed fission was determined to be (1.2{+-}0.4) x 10{sup -4}. This value for the delayed fission probability fits the experimentally observed trend of increasing delayed fission probability with increasing Q value for electron-capture.
Shaughnessy, Dawn A.; Gregorich, Kenneth E.; Adams, Jeb L.; Lane, Michael R.; Laue, Carola A.; Lee, Diana M.; McGrath, Christopher A.; Ninov, Victor; Patin, Joshua B.; Strellis, Dan A.; Sylwester, Eric R.; Wilk, Philip A.; Hoffman, Darleane C.
Exotic fission properties of highly neutron-rich Uranium isotopes
The series of Uranium isotopes with $N=154 \\sim 172$ around the magic number N=162/164 are identified to be thermally fissile. The thermal neutron fission of a typical representative $^{249}$U of this region amenable to synthesis in the radioactive ion beam facilities is considered here. Semiempirical study of fission barrier height and width shows this nucleus to be infinitely stable against spontaneous fission due to increase in barrier width arising out of excess neutrons. Calculation of probability of fragment mass yields and microscopic study in relativistic mean field theory, show this nucleus to undergo a new mode of thermal fission decay termed {\\it multifragmentation fission} where a number of prompt scission neutrons are simultaneously released along with the two heavy fission fragments.
L. Satpathy; S. K. Patra; R. K. Choudhury
Sharp change over from compound nuclear fission to shape dependent quasi fission
Fission fragment mass distribution has been measured from the decay of $^{246}$Bk nucleus populating via two entrance channels with slight difference in mass asymmetries but belonging on either side of the Businaro Gallone mass asymmetry parameter. Both the target nuclei were deformed. Near the Coulomb barrier, at similar excitation energies the width of the fission fragment mass distribution was found to be drastically different for the $^{14}$N + $^{232}$Th reaction compared to the $^{11}$B + $^{235}$U reaction. The entrance channel mass asymmetry was found to affect the fusion process sharply.
T. K. Ghosh; K. Banerjee; C. Bhattacharya; S. Bhattacharya; S. Kundu; P. Mali; J. K. Meena; G. Mukherjee; S. Mukhopadhyay; T. K. Rana; P. Bhattacharya; K. S. Golda
Laser Inertial Fusion-based Energy: Neutronic Design Aspects of a Hybrid Fusion-Fission Nuclear Energy System
it is unlikely that nuclear fission power plants willIn the case of nuclear fission reactions, the fundamentalaspects of nuclear fusion and fission. This approach, termed
Kramer, Kevin James
Emergence of Fusion/Fission Cycling and Self-Organized Criticality from a Simulation Model of Early Complex Polities
H. 1999, Chiefdoms and the Fission-Fusion Process, AmericanEmergence of Fusion/Fission Cycling and Self-Organizedthe fusion and subsequent fission of dynamic political
Griffin, Arthur F
184.108.40.206 Fission Energy . . . . . . . . . 18.104.22.168.1.3.3 Fission-Fusion Hybrids . . . . 1.2 Scope and Purposei CONTENTS Fission Blanket . . . . . . . . . . . . . . . . .
Response to 'A comment on "Signatures of fissile materials: High-energy gamma rays following fission," by Zeev B. Alfassi'
high-energy ? rays following fission" by Zeev B. Alfassi ,radionuclides that are not fission products, but which emittemporal variation of the fission product gamma rays should
On "Sub-Threshold" Reactions Involving Nuclear Fission
We analyze reactions of several types that are naively below threshold but can proceed because of the release of binding energy from nuclear fission and occasionally the formation of Coulombic bound states. These reactions include (i) photofission with pion production and (ii) charged current neutrino-nucleus reactions that lead to fission and/or formation of a Coulomb bound state of a $\\mu^-$ with the nucleus of a fission fragment. We comment on the possible experimental observation of these reactions.
M. Goldhaber; R. Shrock
Experimental Progress Report--Modernizing the Fission Basis
In 2010 a proposal (Modernizing the Fission Basis) was prepared to 'resolve long standing differences between LANL and LLNL associated with the correct fission basis for analysis of nuclear test data'. Collaboration between LANL/LLNL/TUNL has been formed to implement this program by performing high precision measurements of neutron induced fission product yields as a function of incident neutron energy. This new program benefits from successful previous efforts utilizing mono-energetic neutrons undertaken by this collaboration. The first preliminary experiment in this new program was performed between July 24-31, 2011 at TUNL and had 2 main objectives: (1) demonstrating the capability to measure characteristic {gamma}-rays from specific fission products; (2) studying background effects from room scattered neutrons. In addition, a new dual fission ionization chamber has been designed and manufactured. The production design of the chamber is shown in the picture below. The first feasibility experiment to test this chamber is scheduled at the TUNL Tandem Laboratory from September 19-25, 2011. The dual fission chamber design will allow simultaneous exposure of absolute fission fragment emission rate detectors and the thick fission activation foils, positioned between the two chambers. This document formalizes the earlier experimental report demonstrating the experimental capability to make accurate (fission product yields of the 239Pu(n,f) reaction (induced by quasimonoenergetic neutrons). A second experiment (9/2011) introduced an compact double-sided fission chamber into the experimental arrangement, and so the relative number of incident neutrons striking the sample foil at each bombarding energy is limited only by statistics. (The number of incident neutrons often limits the experimental accuracy.) Fission chamber operation was so exceptional that 2 more chambers have been fabricated; thus fission foils of different isotopes may be left in place with sample changes. The scope of the measurements is both greatly expanded and the results become vetted. Experiment 2 is not reported here. A continuing experiment has been proposed for February 2012.
Macri, R A
Neutron flux profile monitor for use in a fission reactor
A neutron flux monitor is provided which consists of a plurality of fission counters arranged as spaced-apart point detectors along a delay line. As a fission event occurs in any one of the counters, two delayed current pulses are generated at the output of the delay line. The time separation of the pulses identifies the counter in which the particular fission event occured. Neutron flux profiles of reactor cores can be more accurately measured as a result.
Kopp, Manfred K. (Oak Ridge, TN); Valentine, Kenneth H. (Lenoir City, TN)
Fission studies with 140 MeV $\\bm?$-Particles
Binary fission induced by 140 MeV $\\alpha$-particles has been measured for $^{\\rm nat}$Ag, $^{139}$La, $^{165}$Ho and $^{197}$Au targets. The measured quantities are the total kinetic energies, fragment masses, and fission cross sections. The results are compared with other data and systematics. A minimum of the fission probability in the vicinity $Z^2/A=24$ is observed.
A. Buttkewitz; H. H. Duhm; F. Goldenbaum; H. Machner; W. Strauss
A New Method of Prompt Fission Neutron Energy Spectrum Unfolding
The prompt neutron emission in spontaneous fission of 252 Cf has been investigated applying digital signal electronics along with associated digital signal processing algorithms. The goal was to find out the reasons of a long time existing discrepancy between theoretical calculations and the measurements of prompt fission neutron (PFN) emission dependence on the total kinetic energy (TKE) of fission fragments (FF). On the one hand the 252 Cf (sf) reaction is one of the main references for nuclear data
O. V. Zeynalova; Sh. Zeynalov; F.?J. Hambsch; S. Oberstedt
Segregation of Fission Products to Dislocations in Uranium Dioxide
Abstract Scope, Irradiation of nuclear fuel leads to the formation of extended ... very important to understand the interaction of fission products with dislocations.
Glass Ceramic Waste Form Development for Fission Products from ...
Symposium, Materials Issues in Nuclear Waste Management in the 21st Century. Presentation Title, Glass Ceramic Waste Form Development for Fission ...
September 2013 Most Viewed Documents for Fission And Nuclear...
Fission And Nuclear Technologies Estimation of gas leak rates through very small orifices and channels. From sealed PuOsub 2 containers under accident conditions Bomelburg,...
Novel Fission-Product Separation Based on Room Temperature ...
macrocyclic extractants and transport in new ... Future Research Plans 1. Synthesis and Optimization of ILs Tailored for Solvent Extraction of Fission ...
Thermodynamic Modelling of Volatile Fission Products during SFR ...
The creation of fission products can modify the physical and chemical properties of the nuclear fuel behaviour during operating conditions. A thermodynamic ...
Theoretical Investigation on Interplay of Defect Clusters and Fission ...
A prominent effect of the self-defect clusters in bulk matrix on the thermodynamic behavior of fission gases is found, a thermodynamic competition between the ...
Multiscale Computer Simulation of Fission Gas Release in Oxide Fuels
Central to the retention and release of fission gases is the evolution of bubbles existing on grain boundaries and grain triple junctions. This presentation will ...
Sensitivity of measured fission yields on prompt-neutron corrections
The amount of emitted prompt neutrons from the fission fragments increases as a function of excitation energy. Yet it is not fully understood whether the increase in \
A. Al-Adili; F. -J. Hambsch; S. Pomp; S. Oberstedt
the destruction of cities by nuclear fission killed millionsnuclear energy. Elizabeth Hodes is a professor of mathematics at Santa Barbara City
A chromatographic adsorption process is presented for the separation of plutonium from other fission products formed by the irradiation of uranium. The plutonium and the lighter element fission products are adsorbed on a sulfonated phenol-formaldehyde resin bed from a nitric acid solution containing the dissolved uranium. Successive washes of sulfuric, phosphoric, and nitric acids remove the bulk of the fission products, then an eluate of dilute phosphoric and nitric acids removes the remaining plutonium and fission products. The plutonium is selectively removed by passing this solution through zirconium phosphate, from which the plutonium is dissolved with nitric acid. This process provides a convenient and efficient means for isolating plutonium.
Boyd, G.E.; Adamson, A.W.; Schubert, J.; Russell, E.R.
Generalized Energy-Dependent Q Values for Fission
We extend Madland's parameterization of the energy release in fission to obtain the dependence of the fission Q value for major and minor actinides on the incident neutron energies in the range 0 {le} E{sub n} {le} 20 MeV. Our parameterization is based on the actinide evaluations recommended for the ENDF/B-VII.1 release. This paper describes the calculation of energydependent fission Q values based on the calculation of the prompt energy release in fission by Madland. This calculation was adopted for use in the LLNL ENDL database and then generalized to obtain the prompt fission energy release for all actinides. Here the calculation is further generalized to the total energy release in fission. There are several stages in a fission event, depending on the time scale. Neutrons and gammas may be emitted at any time during the fission event.While our discussion here is focussed on compound nucleus creation by an incident neutron, similar parameterizations could be obtained for incident gammas or spontaneous fission.
Vogt, R
ORNL fission product release tests VI-6
The ORNL fission product release tests investigate release and transport of the major fission products from high-burnup fuel under LWR accident conditions. The two most recent tests (VI-4 and VI-5) were conducted in hydrogen. In three previous tests in this series (VI-1, VI-2, and VI-3), which had been conducted in steam, the oxidized Zircaloy cladding remained largely intact and acted as a barrier to steam reaction with the UO{sub 2}. Test VI-6 was designed to insure significant oxidation of the UO{sub 2} fuel, which has been shown to enhance release of certain fission products, especially molybdenum and ruthenium. The BR3 fuel specimen used in test VI-6 will be heated in hydrogen to 2300 K; the Zircaloy cladding is expected to melt and runoff at {approximately}2150 K. Upon reaching the 2300 K test temperature, the test atmosphere will be changed to steam, and that temperature will be maintained for 60 min, with the three collection trains being operated for 2-, 18-, and 40-min periods. The releases of {sup 85}Kr and {sup 137}Cs will be monitored continuously throughout the test. Posttest analyses of the material collected on the three trains will provide results on the release and transport of Mo, Ru, Sb, Te, Ba, Ce, and Eu as a function of time at 2300 K. Continuous monitoring of the hydrogen produced during the steam atmosphere period at high temperature will provide a measure of the oxidation rate of the cladding and fuel. Following delays in approval of the safety documentation and in decontamination of the hot cell and test apparatus, test VI-6 will be conducted in late May.
Osborne, M.F.; Lorenz, R.A.; Collins, J.L.; Lee, C.S.
Nuclear multifragmentation and fission: similarity and differences
Thermal multifragmentation of hot nuclei is interpreted as the nuclear liquid–fog phase transition deep inside the spinodal region. The experimental data for p(8.1GeV) + Au collisions are analyzed. It is concluded that the decay process of hot nuclei is characterized by two size parameters: transition state and freeze-out volumes. The similarity between dynamics of fragmentation and ordinary fission is discussed. The IMF emission time is related to the mean rupture time at the multi-scission point, which corresponds to the kinetic freeze-out configuration. 1
V. Karnaukhov; H. Oeschler; S. Avdeyev; V. Rodionov; V. Kirakosyan; A. Simonenko; P. Rukoyatkin; A. Budzanowski; W. Karcz; I. Skwirczynska; B. Czech; L. Chulkov; E. Kuzmin; E. Norbeck; A. Botvina
Thermal multifragmentation of hot nuclei is interpreted as the nuclear liquid--fog phase transition deep inside the spinodal region. The experimental data for p(8.1GeV) + Au collisions are analyzed. It is concluded that the decay process of hot nuclei is characterized by two size parameters: transition state and freeze-out volumes. The similarity between dynamics of fragmentation and ordinary fission is discussed. The IMF emission time is related to the mean rupture time at the multi-scission point, which corresponds to the kinetic freeze-out configuration.
The separation of uranium and plutonium from neutronirradiated uranium is described. The neutron-irradiated uranium is dissolved in nitric acid to provide an aqueous solution 3N in nitric acid. The fission products of the solution are extruded by treating the solution with dibutyl carbitol substantially 1.8N in nitric acid. The organic solvent phase is separated and neutralized with ammonium hydroxide and the plutonium reduced with hydroxylamine base to the trivalent state. Treatment of the mixture with saturated ammonium nitrate extracts the reduced plutonium and leaves the uranium in the organic solvent.
Nicholls, C.M.; Wells, I.; Spence, R.
Ceramics in fission and fusion technology
The role of ceramic components in fission and fusion reactors is described. Almost all of the functions normally performed by ceramics, except mechanical, are required of nuclear ceramics. The oxides of uranium and plutonium are of predominant importance in nuclear applications, but a number of other ceramics play peripheral roles. The unique service conditions under which nuclear ceramics must operate include intense radiation fields, high temperatures and large temperature gradients, and aggressive chemical environments. Examples of laboratory research designed to broaden understanding of the behavior of uranium dioxide in such conditions are given. The programs described include high temperature vaporization, diffusional processes, and interaction with hydrogen.
Olander, D.R.
Uranium mill monitoring for natural fission reactors
Isotopic monitoring of the product stream from operating uranium mills is proposed for discovering other possible natural fission reactors; aspects of their occurrence and discovery are considered. Uranium mill operating characteristics are formulated in terms of the total uranium capacity, the uranium throughput, and the dilution half-time of the mill. The requirements for detection of milled reactor-zone uranium are expressed in terms of the dilution half-time and the sampling frequency. Detection of different amounts of reactor ore with varying degrees of /sup 235/U depletion is considered.
Apt, K.E.
FISSION OF 238U INDUCED BY INELASTIC SCATTERING OF 120 MeV 4-PARTICLES
Physics and Chemistry of Fission, Rochester, 1973, Vol. 2,kinetic energy (a) and the fission coincidence spectrum (b)for second and third chance fission are indicated by arrows.
Back, B.B.
REC Tracking Systems Design Guide
OAK-B135 The Design Guide is presented in three parts. Section II describes the need for REC tracking, the two principal tracking methods available, and, in simple terms, the operation of certificate-based systems. Section III presents the major issues in the design of certificate-based tracking systems and discusses the advantages and disadvantages of alternative solutions. Finally, Section IV offers design principles or recommendations for most of these issues.
Meredith Wingate
Tracking the Intractability of Melanomas
Tracking the Intractability of Melanomas Important new information about the way melanoma cancer cells fight for their lives has been uncovered by researchers from the National...
nuclear energy legislation on track
07/8 - NUCLEAR ENERGY LEGISLATION ON TRACK ... the safety and economic viability of nuclear power, the management of nuclear waste, the advancement ...
Fast Track Special Project Proposal
A fast track special project is defined as a one-time Division directed endeavor that creates ... project will not result in future operating expenses. ... Cost Analysis
TREC 2004 Terabyte Track Guidelines
... This year's track will use a collection of Web data crawled from Web sites in the .gov domain during early ... White space is used to separate columns. ...
A process of regenerating a magnesium-thorium alloy contaminated with fission products, protactinium, and uranium is presented. A molten mixture of KCl--LiCl-MgCl/sub 2/ is added to the molten alloy whereby the alkali, alkaline parth, and rare earth fission products (including yttrium) and some of the thorium and uranium are chlorinated and
Chiotti, P.
Fission product separation from hexavalent plutonium by bismuth phosphate precipitation of the fission products is described. The precipitation, according to this invention, is improved by coprecipitating ceric and zirconium phosphates (0.05 to 2.5 grams/liter) with the bismuth phosphate.
Seaborg, G.T.; Thompson, S.G.; Davidson, N.R.
Electroplating method for producing ultralow-mass fissionable deposits
A method for producing ultralow-mass fissionable deposits for nuclear reactor dosimetry is described, including the steps of holding a radioactive parent until the radioactive parent reaches secular equilibrium with a daughter isotope, chemically separating the daughter from the parent, electroplating the daughter on a suitable substrate, and holding the electroplated daughter until the daughter decays to the fissionable deposit.
Ruddy, Francis H. (Monroeville, PA)
Nuclear Thermal Rockets: The Physics of the Fission Reactor
Nuclear Thermal Rockets: The Physics of the Fission Reactor Shane D. Ross Control and Dynamical combustion are those powered by nuclear fission. Comparison of Chemical and Nuclear Rockets. Most existent.g., hydrogen and oxygen). In a nuclear rocket, or more precisely, a nuclear thermal rocket, the propellant
Ross, Shane
Fission energy program of the US Department of Energy, FY 1981
Information is presented concerning the National Energy Plan and fission energy policy; fission energy program management; converter reactor systems; breeder reactor systems; and special nuclear evaluations and systems.
Not Available
Applications of Event-by-Event Fission Modeling with FREYA
The recently developed code FREYA (Fission Reaction Event Yield Algorithm) generates large samples of complete fission events, consisting of two receding product nuclei as well as a number of neutrons and photons, all with complete kinematic information. Thus it is possible to calculate arbitrary correlation observables whose behavior may provide unique insight into the fission process. We first discuss the present status of FREYA, which has now been extended to include spontaneous fission. Concentrating on {sup 239}Pu(n{sub th},f), {sup 240}Pu(sf) and {sup 252}Cf(sf), we discuss the neutron multiplicity correlations, the dependence of the neutron energy spectrum on the neutron multiplicity, and the relationship between the fragment kinetic energy and the number of neutrons and their energies. We also suggest novel fission observables that could be measured with modern detectors.
Vogt, R; Randrup, J
Using prediction markets to track information flows: Evidence from Google
In the last three years, Google has conducted the largest corporate experiment with prediction markets we are aware of. In this paper, we illustrate how markets can be used to study how an organization processes information. We document a number of biases in Google's markets, most notably an optimistic bias. Newly hired employees are on the optimistic side of these markets, and optimistic biases are significantly more pronounced on days when Google stock is appreciating. We find correlated trading among employees who sit within a few feet of one another and employees with social or work relationships. The results are interesting in light of recent research on the role of optimism in entrepreneurial firms, as well as recent work on the importance of geographic and social proximity in explaining information flows in firms and markets. 1
Bo Cowgill; Justin Wolfers; Wharton U. Penn; Eric Zitzewitz; Ulrike Malmendier; Kevin M. Murphy; Michael Ostrovsky; Paul Oyer; Parag Pathak; Tanya Rosenblat
The TREC question answering track
The Text REtrieval Conference (TREC) question answering track is an effort to bring the benefits of large-scale evaluation to bear on a question answering (QA) task. The track has run twice so far, first in TREC-8 and again in TREC-9. In each case, the ...
Ellen M. Voorhees
Tracking defect warnings across versions
Various static analysis tools will analyze a software artifact in order to identify potential defects, such as misused APIs, race conditions and deadlocks, and security vulnerabilities. For a number of reasons, it is important to be able to track the ... Keywords: FindBugs, Java, bug histories, bug tracking, static analysis
Jaime Spacco; David Hovemeyer; William Pugh
Biologically plausible algorithms for motion saliency and tracking
Tracking . . . . . . . . . . . . . . . . . . . . . . . . . .5.3.6 Scale Adaptive Tracking . . . . . . . . . . 5.3.7Experiment1: Saliency affects tracking performance . . . . .
Mahadevan, Vijay
PIA - HS Correspondence Tracking System (HSCT) | Department of...
Correspondence Tracking System (HSCT) PIA - HS Correspondence Tracking System (HSCT) PIA - HS Correspondence Tracking System (HSCT) PIA - HS Correspondence Tracking System (HSCT)...
PIA - Security Clearance Tracking System | Department of Energy
Security Clearance Tracking System PIA - Security Clearance Tracking System PIA - Security Clearance Tracking System PIA - Security Clearance Tracking System More Documents &...
Budding and Fission of a multiphase vesicle
We present a model of bi-phasic vesicle in the limit of large surface tension. In this regime, the vesicle is completely stretched and well described by two spherical caps with a fold which concentrates the membrane stress. The conservation laws and geometric constraints restrict the space of possible shapes to a pair of solutions labeled by a parameter $\\tau$ given by {\\it line tension/pressure}. For a given $\\tau$ value, the two solutions differ by the length of the interface between domains. For a critical value $\\tau\\_c$, the two vesicle shapes become identical and no solution exists above this critical value. This model sheds new light on two proposed mechanisms (osmotic shocks and molecule absorption) to explain the budding and the fission in recent experiments.
Jean-Marc Allain; Martine Ben Amar
Structural Materials for Fission and Fusion Energy
Structural materials represent the key for containment of nuclear fuel and fission products as well as reliable and thermodynamically efficient production of electrical energy from nuclear reactors. Similarly, high-performance structural materials will be critical for the future success of proposed fusion energy reactors, which will subject the structures to unprecedented fluxes of high-energy neutrons along with intense thermomechanical stresses. Advanced materials can enable improved reactor performance via increased safety margins and design flexibility, in particular by providing increased strength, thermal creep resistance and superior corrosion and neutron radiation damage resistance. In many cases, a key strategy for designing highperformance radiation-resistant materials is based on the introduction of a high, uniform density of nanoscale particles that simultaneously provide good high temperature strength and neutron radiation damage resistance.
Zinkle, Steven J [ORNL; Busby, Jeremy T [ORNL
Detecting fission from special nuclear material sources
A neutron detector system for discriminating fissile material from non-fissile material wherein a digital data acquisition unit collects data at high rate, and in real-time processes large volumes of data directly into information that a first responder can use to discriminate materials. The system comprises counting neutrons from the unknown source and detecting excess grouped neutrons to identify fission in the unknown source. The system includes a graphing component that displays the plot of the neutron distribution from the unknown source over a Poisson distribution and a plot of neutrons due to background or environmental sources. The system further includes a known neutron source placed in proximity to the unknown source to actively interrogate the unknown source in order to accentuate differences in neutron emission from the unknown source from Poisson distributions and/or environmental sources.
Rowland, Mark S. (Alamo, CA); Snyderman, Neal J. (Berkeley, CA)
Prescission neutron multiplicity and fission probability from Langevin dynamics of nuclear fission
A theoretical model of one-body nuclear friction which was developed earlier, namely the chaos-weighted wall formula, is applied to a dynamical description of compound nuclear decay in the framework of the Langevin equation coupled with statistical evaporation of light particles and photons. We have used both the usual wall formula friction and its chaos-weighted version in the Langevin equation to calculate the fission probability and prescission neutron multiplicity for the compound nuclei $^{178}$W, $^{188}$Pt, $^{200}$Pb, $^{213}$Fr, $^{224}$Th, and $^{251}$Es. We have also obtained the contributions of the presaddle and postsaddle neutrons to the total prescission multiplicity. A detailed analysis of our results leads us to conclude that the chaos-weighted wall formula friction can adequately describe the fission dynamics in the presaddle region. This friction, however, turns out to be too weak to describe the postsaddle dynamics properly. This points to the need for a suitable explanation for the enhanced neutron emission in the postsaddle stage of nuclear fission.
Gargi Chaudhuri; Santanu Pal
In today's compliant-driven environment, fissionable material handlers are inundated with work control rules and procedures in carrying out nuclear operations. Historically, human errors are one of the key contributors of various criticality accidents. Since moving and handling fissionable materials are key components of their job functions, any means that can be provided to assist operators in facilitating fissionable material moves will help improve operational efficiency and enhance criticality safety implementation. From the criticality safety perspective, operational issues have been encountered in Lawrence Livermore National Laboratory (LLNL) plutonium operations. Those issues included lack of adequate historical record keeping for the fissionable material stored in containers, a need for a better way of accommodating operations in a research and development setting, and better means of helping material handlers in carrying out various criticality safety controls. Through the years, effective means were implemented including better work control process, standardized criticality control conditions (SCCC) and relocation of criticality safety engineers to the plutonium facility. Another important measure taken was to develop a computer data acquisition system for criticality safety assessment, which is the subject of this paper. The purpose of the Criticality Special Support System (CSSS) is to integrate many of the proven operational support protocols into a software system to assist operators with assessing compliance to procedures during the handling and movement of fissionable materials. Many nuclear facilities utilize mass cards or a computer program to track fissionable material mass data in operations. Additional item specific data such as, the presence of moderators or close fitting reflectors, could be helpful to fissionable material handlers in assessing compliance to SCCC's. Computer-assist checking of a workstation material inventory against the designated SCCC to enhance the material movement was also recognized. The following three additional functions of the CSSS were requested by operational personnel: additional record keeping, assisting room inventory Material at Risk (MAR) calculations and generating the material label to be placed on a storage can. In 1998, a preliminary CSSS concept was presented to all key stakeholders for the feasibility of such an application. Subsequently, the CSSS was developed with full participation of all stakeholders including fissionable material handlers. In 2003, five CSSS workstations were deployed in the plutonium facility for beta testing and resolving any issues from the field uses. Currently, the CSSS is deployed in all laboratories in the LLNL Plutonium Facility. Initial deployment consists of only a few of the full system functions described in this paper. Final deployment of all functions will take a few more years to assure the system meets quality assurance requirements of a safety significant system.
Claybourn, R V; Huang, S T
Proton-induced fission of heavy nuclei at intermediate energies
The intermediate energy proton-induced fission of 241Am, 238$U and 237$Np is studied. The inelastic interactions of protons and heavy nuclei are described by a CRISP model, in which the reaction proceeds in two steps. The first one corresponds fast cascade, where a series of individual particle-particle collisions occurs within the nucleus. It leaves a highly excited cascade residual nucleus, assumed to be in thermal equilibrium. Subsequently, in the second step the excited nucleus releases its energy by evaporation of neutrons and light charged particles as well. Both the symmetric and asymmetric fission are regarded, and the fission probabilities are obtained from CRISP code calculations, by means of statistical weighting factors. The fission cross sections, the fissility of the fissioning nuclei, and the number of nucleons lost by the target - before and after fission - are calculated and compared to experiments for 660 MeV protons incident on 241Am, 238$U and 237$Np. Some of the model predictions are in full compliance to the experiments. We conclude that our two step model provides a reasonable description of the medium energy proton-induced fission.
A. Deppman; E. Andrade-II; V. Guimaraes; G. S. Karapetyan; A. R. Balabekyan; N. A. Demekhina
Unified description of fission in fusion and spallation reactions
We present a statistical-model description of fission, in the framework of compound-nucleus decay, which is found to simultaneously reproduce data from both heavy-ion-induced fusion reactions and proton-induced spallation reactions at around 1 GeV. For the spallation reactions, the initial compound-nucleus population is predicted by the Li\\`{e}ge Intranuclear Cascade Model. We are able to reproduce experimental fission probabilities and fission-fragment mass distributions in both reactions types with the same parameter sets. However, no unique parameter set was obtained for the fission probability. The introduction of fission transients can be offset by an increase of the ratio of level-density parameters for the saddle-point and ground-state configurations. Changes to the finite-range fission barriers could be offset by a scaling of the Bohr-Wheeler decay width as predicted by Kramers. The parameter sets presented allow accurate prediction of fission probabilities for excitation energies up to 300 MeV and spins up to 60 \\hbar.
Davide Mancusi; Robert J. Charity; Joseph Cugnon
The prompt neutron emission in spontaneous fission of {sup 252}Cf has been investigated applying digital signal electronics along with associated digital signal processing algorithms. The goal was to find out the reasons of a long time existing discrepancy between theoretical calculations and the measurements of prompt fission neutron (PFN) emission dependence on the total kinetic energy (TKE) of fission fragments (FF). On the one hand the {sup 252}Cf(sf) reaction is one of the main references for nuclear data, on the other hand the understanding of PFN emission mechanism is very important for nuclear fission theory. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 10{sup 7} fission fragment-neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. For the first time the dependence of the number of emitted neutrons as a function of total kinetic energy (TKE) of the fragments is in very good agreement with theoretical calculations in the range of TKE from 140-220 MeV.
Zeynalova, O. V. [Moscow State Institute of Radioengineering, Electronics and Automation, Moscow (Russian Federation); Joint Institute for Nuclear Research, Dubna (Russian Federation); Zeynalov, Sh. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Hambsch, F.-J.; Oberstedt, S. [EC-JRC-Institute for Reference Materials and Measurements, Geel (Belgium)
The Qweak tracking system
The Q{sub weak}{sup p} experiment will measure the parity-violating elastic e-p scattering asymmetry to extract the weak charge of the proton. The experiment employs a toroidal magnet to focus electrons scattered at 8{sup o} {+-} 2{sup o}, corresponding to Q{sup 2} {approx} 0.03 (GeV/c){sup 2}, on eight Cerenkov detectors located in the focal plane of the spectrometer. Since the asymmetry is proportional to Q{sup 2}, it is crucial to obtain an accurate measure of the acceptance-averaged value of Q{sup 2}. A tracking system will be used in a low-rate counting mode, allowing individual events to be observed. This will enable a determination of the average Q{sup 2} by measuring the scattering angle and interaction vertex, for mapping the response across the surface of the Cerenkov detectors, and for the dilution of the Cerenkov detector signal by background.
K.H. Grimm; Qweak Collaboration
Semiclassical Interpretation of the Mass Asymmetry in Nuclear Fission
We give a semiclassical interpretation of the mass asymmetry in the fission of heavy nuclei. Using only a few classical periodic orbits and a cavity model for the nuclear mean field, we reproduce the onset of left-right asymmetric shapes at the fission isomer minimum and the correct topology of the deformation energy surface in the region of the outer fission barrier. We point at the correspondence of the single-particle quantum states responsible for the asymmetry with the leading classical orbits, both lying in similar equatorial planes perpendicular to the symmetry axis of the system.
M. Brack; S. M. Reimann; M. Sieber
Fission converter heat removal and safety under accident conditions
The design and safety of the heat removal system of the Massachusetts Institute of Technology (MIT) design for a fission converter-based epithermal beam is discussed in this paper. Plate-type reactor fuel elements, used in the MIT research reactor (MITR-II), are also used for the fission converter. This fission converter-based beam provides epithermal neutron fluxes at the patient position in excess of 10{sup 10} n/cm{sup 2}s with very low contamination of fast neutrons and gamma rays.
Sutharshan, B.; Todreas, N.E.; Harling, O.K. [Massachusetts Inst. of Technology, Cambridge, MA (United States)
Coherent bremsstrahlung and GDR width from 252Cf cold fission
The energy spectrum of the high energy gamma-rays in coincidence with the prompt gamma rays has been measured for the spontaneous fission of 252Cf. The nucleus-nucleus coherent bremsstrahlung of the accelerating fission fragments is observed and the result has been substantiated with a theoretical calculation based on the coulomb acceleration model. The width of the giant dipole resonance (GDR) decay from the excited fission fragments has been extracted for the first time and compared with the thermal shape fluctuation model (TSFM) in the liquid drop formalism. The extracted GDR width is significantly smaller than the predictions of TSFM.
Deepak Pandit; S. Mukhopadhyay; Srijit Bhattacharya; Surajit Pal; A. De; S. R. Banerjee
Neutrinos, Fission Cycling, and the r-process
It has long been suggested that fission cycling may play an important role in the r-process. Fission cycling can only occur in a very neutron rich environment. In traditional calculations of the neutrino driven wind of the core-collapse supernova, the environment is not sufficiently neutron rich to produce the r-process elements. However, we show that with a reduction of the electron neutrino flux coming from the supernova, fission cycling does occur and furthermore it produces an abundance pattern which is consistent with observed r-process abundance pattern in halo stars. Such a reduction can be caused by active-sterile neutrino oscillations or other new physics.
J. Beun; G. C. Mclaughlin; R. Surman; W. R. Hix; J. Beun
The effect of the right-left asymmetry is considered in the predicted earlier electric dipole radiation from fission fragments arising due to the Strutinski— Denisov induced polarisation mechanism. The magnitude of the asymmetry parameter is on the level of 10 ?3. That is in agreement with the recent experimental data on the radiative ROT effect in 235 U fission induced by cold polarised neutrons. PACS: 24.80.+y, 24.75.+i, 24.70.+s Key words: Fission, asymmetry, radiation, ROT-effect
F. F. Karpeshin
In 2010 a proposal (Modernizing the Fission Basis) was prepared to 'resolve long standing differences between LANL and LLNL associated with the correct fission basis for analysis of nuclear test data'. Collaboration between LANL/LLNL/TUNL has been formed to implement this program by performing high precision measurements of neutron induced fission product yields as a function of incident neutron energy. This new program benefits from successful previous efforts utilizing mono-energetic neutrons undertaken by this collaboration. The first preliminary experiment in this new program was performed between July 24-31, 2011 at TUNL and had 2 main objectives: (1) demonstrating the capability to measure characteristic {gamma}-rays from specific fission products; (2) studying background effects from room scattered neutrons. In addition, a new dual fission ionization chamber has been designed and manufactured. The production design of the chamber is shown in the picture below. The first feasibility experiment to test this chamber is scheduled at the TUNL Tandem Laboratory from September 19-25, 2011. The dual fission chamber design will allow simultaneous exposure of absolute fission fragment emission rate detectors and the thick fission activation foils, positioned between the two chambers. This document formalizes the earlier experimental report demonstrating the experimental capability to make accurate (< 2 %) precision gamma-ray spectroscopic measurements of the excitation function of high fission product yields of the 239Pu(n,f) reaction (induced by quasimonoenergetic neutrons). A second experiment (9/2011) introduced an compact double-sided fission chamber into the experimental arrangement, and so the relative number of incident neutrons striking the sample foil at each bombarding energy is limited only by statistics. (The number of incident neutrons often limits the experimental accuracy.) Fission chamber operation was so exceptional that 2 more chambers have been fabricated; thus fission foils of different isotopes may be left in place with sample changes. The scope of the measurements is both greatly expanded and the results become vetted. Experiment 2 is not reported here. A continuing experiment has been proposed for February 2012.
Sensitivity analysis of the fission gas behavior model in BISON.
This report summarizes the result of a NEAMS project focused on sensitivity analysis of a new model for the fission gas behavior (release and swelling) in the BISON fuel performance code of Idaho National Laboratory. Using the new model in BISON, the sensitivity of the calculated fission gas release and swelling to the involved parameters and the associated uncertainties is investigated. The study results in a quantitative assessment of the role of intrinsic uncertainties in the analysis of fission gas behavior in nuclear fuel.
Swiler, Laura Painton; Pastore, Giovanni [Idaho National Laboratory, Idaho Fall, ID; Perez, Danielle [Idaho National Laboratory, Idaho Fall, ID; Williamson, Richard [Idaho National Laboratory, Idaho Fall, ID
J. Beun; G. C. McLaughlin; R. Surman; W. R. Hix
Robust Multiple Car Tracking With Occlusion Reasoning
BERKELEY Robust Multiple Car Tracking with OcclusionAND HIGHWAYS Robust Multiple Car Tracking with Occlusiondraws decisions like "stalled car in lane 2 detected", "high
Koler, Dieter; Weber, Joseph; Malik, Jitendra
The Automatic Library Tracking Database
A library tracking database has been developed and put into production at the National Institute for Computational Sciences and the Oak Ridge Leadership Computing Facility (both located at Oak Ridge National Laboratory.) The purpose of the library tracking database is to track which libraries are used at link time on Cray XT5 Supercomputers. The database stores the libraries used at link time and also records the executables run in a batch job. With this data, many operationally important questions can be answered such as which libraries are most frequently used and which users are using deprecated libraries or applications. The infrastructure design and reporting mechanisms are presented along with collected production data.
Fahey, Mark R [ORNL; Jones, Nicholas A [ORNL; Hadri, Bilel [ORNL
Measurements of actinide-fission product yields in Caliban and Prospero metallic core reactor fission neutron fields
In the 1970's and early 1980's, an experimental program was performed on the facilities of the CEA Valduc Research Center to measure several actinide-fission product yields. Experiments were, in particular, completed on the Caliban and Prospero metallic core reactors to study fission-neutron-induced reactions on {sup 233}U, {sup 235}U, and {sup 239}Pu. Thick actinide samples were irradiated and the number of nuclei of each fission product was determined by gamma spectrometry. Fission chambers were irradiated simultaneously to measure the numbers of fissions in thin deposits of the same actinides. The masses of the thick samples and the thin deposits were determined by mass spectrometry and alpha spectrometry. The results of these experiments will be fully presented in this paper for the first time. A description of the Caliban and Prospero reactors, their characteristics and performances, and explanations about the experimental approach will also be given in the article. A recent work has been completed to analyze and reinterpret these measurements and particularly to evaluate the associated uncertainties. In this context, calculations have also been carried out with the Monte Carlo transport code Tripoli-4, using the published benchmarked Caliban description and a three-dimensional model of Prospero, to determine the average neutron energy causing fission. Simulation results will be discussed in this paper. Finally, new fission yield measurements will be proposed on Caliban and Prospero reactors to strengthen the results of the first experiments. (authors)
Casoli, P.; Authier, N. [CEA, Centre de Valduc, 21120 Is-sur-Tille (France); Laurec, J.; Bauge, E.; Granier, T. [CEA, Centre DIF, 91297 Arpajon (France)
Event-by-event study of neutron observables in spontaneous and thermal fission
The event-by-event fission model FREYA is extended to spontaneous fission of actinides and a variety of neutron observables are studied for spontaneous fission and fission induced by thermal neutrons with a view towards possible applications for detection of special nuclear materials.
R. Vogt; J. Randrup
Systems Modeling for the Laser Fusion-Fission Energy (LIFE) Power Plant
W. R. Meier et al.
Molten Salt Fuel Version of Laser Inertial Fusion Fission Energy (LIFE)
R. W. Moir; H. F. Shaw; A. Caro; Larry Kaufman; J. F. Latkowski; J. Powers; P. E. A. Turchi
PHYSICAL REVIEW VOLUME 183; NUMBER 4 20 J ULY 1969 Single-Particle Theory of Fission*
manuscript received 6 December 1968) The single-particle aspects of nuclear fission theories are investigated
Nd:Glass Laser Design for Laser ICF Fission Energy (LIFE)
John Caird et al.
Radiological Source Registry and Tracking
Radiological Source Registry and Tracking (RSRT) Radiological Source Registry and Tracking (RSRT) Home HSS Logo Radiological Source Registry and Tracking (RSRT) Department of Energy (DOE) Notice N 234.1 Reporting of Radioactive Sealed Sources has been superseded by DOE Order O 231.1B Environment, Safety and Health Reporting. O 231.1B identifies the requirements for centralized inventory and transaction reporting for radioactive sealed sources. Each DOE site/facility operator that owns, possesses, uses or maintains in custody those accountable radioactive sealed sources identified in Title 10 Code of Federal Regulation Part 835, Occupational Radiation Protection (10 CFR 835), Appendix E, and International Atomic Energy Agency (IAEA) Categories 1 and 2 radioactive sealed sources identified in Attachment 5, Appendix A of O 321.1B, will submit information to the DOE Radiological Source Registry and Tracking (RSRT) System.
Drizzle Suppression in Ship Tracks
Although drizzle was a relatively infrequent occurrence during the Monterey Area Ship Track study, diverse measurements from several sources produced data signals consistent with a reduction in drizzle drops in stratus clouds affected by ship ...
Ronald J. Ferek; Timothy Garrett; Peter V. Hobbs; Scott Strader; Doug Johnson; Jonathan P. Taylor; Kurt Nielsen; Andrew S. Ackerman; Yefim Kogan; Qingfu Liu; Bruce A. Albrecht; David Babb
Poleward Deflection of Storm Tracks
An analysis of 11 years of European Centre for Medium-Range Weather Forecasts data focuses primarily on the vertically averaged high-frequency transients. The conclusions are discussed in the context of (a) the winter storm track, (b) monthly ...
Isidoro Orlanski
Automatic Library Tracking Database Infrastructure
Libraries » ALTD Libraries » ALTD ALTD Automatic Library Tracking Database Infrastructure To track and monitor library usage and better serve your software needs, we have enabled the Automatic Library Tracking Database (ALTD) on our prodcution systems, Hopper and Edison. ALTD is also availailable on Carver, but has not enabled for all users by default yet. ALTD, developed by National Institute for Computational Sciences, automatically and transparently tracks all libraries linked into an application at compile time, as well as the libraries used at run time, by intercepting the linker (ld) and the job launcher (aprun, or mpirun). It is a light-weight tool, and should not change your experience with compilation and execution of codes on the machine. However, if you encounter any problems due to ALTD,
110101BenefitsNuclearFission.ppt [Read-Only]
Benefits of Nuclear Fission to Benefits of Nuclear Fission to the Civilian Space Program Gary Langford Fission Project Manager NASA MSFC NERAC Nov. 6, 2001 2 * Outer solar system exploration. * Planetary or lunar surface missions (robotic or human). * High-performance propulsion for human missions. * Advanced applications. Uses of Nuclear Fission in the Civilian Space Program Highly advanced propulsion, extremely high power surface applications. 3 2000 2010 2020 2030 2040 Phase 1 * 10-500 kW NEP * 10-500 kW spacecraft & surface powerplants Phase 3 * 10-1000 MW, 0.1-1 kg/kW NEP * >2000 s Isp gas/plasma-based NTR Phase 2 * 1-100 MW, 1-10 kg/kW NEP * 900-1000 s Isp solid- core NTR * Multi-MW space & surface powerplants Kuiper Belt Exploration Triton Lander Europa Ocean Science Station Pluto Orbiter Large Asteroids Io Volcanic Observer
Numerical Simulation of Fission Gas Bubble Coarsening in Nuclear ...
The gas from these bubbles is periodically re-dissolved back in the nuclear fuel by very high-energy fission fragments that pass either through or near the gas ...
Fission Cross Section Measurements of Actinides at LANSCE
Fission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications. By combining measurement at two LANSCE facilities, Lujan Center and the Weapons Neutron Research center (WNR), differential cross sections can be measured from sub-thermal energies up to 200 MeV. Incident neutron energies are determined using the time-of-flight method, and parallel-plate ionization chambers are used to measure fission cross sections relative to the 235U standard. Recent measurements include the 233, 238U, 239-242Pu, and 243Am neutron-induced fission cross sections. In this paper preliminary results for fission cross sections of 243Am and 233U will be presented.
F. Tovesson; A. B. Laptev; T. S. Hill
Recent advances in modeling fission cross sections over intermediate structures
More accurate fission cross section calculations in presence of underlying intermediate structure are strongly desired. This paper recalls the common approximations used below the fission threshold and quantifies their impact. In particular, an exact expanded R-matrix Monte Carlo calculation of the intermediate structure, deeply mixed with the fluctuations of the class-I and II decay amplitudes, is shown. This paper also insists on the microscopic structure of the level densities as a function of the nucleus deformation and show preliminary neutron induced fission cross section calculations for {sup 239}Pu and {sup 240}Pu using newly calculated combinatorial level densities. Comparisons with recent evaluated and measured fission cross sections are made.
Bouland, Olivier [Los Alamos National Laboratory; Lynn, J. Eric [Los Alamos National Laboratory; Talou, Patrick [Los Alamos National Laboratory
Browse by Discipline -- E-print Network Subject Pathways: Fission...
Fission and Nuclear Technologies A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z Go to Research Collections E-prints Provided...
Parallel Fission Bank Algorithms in Monte Carlo Criticality Calculations
In this work we describe a new method for parallelizing the source iterations in a Monte Carlo criticality calculation. Instead of having one global fission bank that needs to be synchronized, as is traditionally done, our ...
Romano, Paul Kollath
Transcriptional regulatory network for sexual differentiation in fission yeast
Abstract Background Changes in gene expression are hallmarks of cellular differentiation. Sexual differentiation in fission yeast (Schizosaccharomyces pombe) provides a model system for gene expression programs accompanying and driving cellular...
Mata, Juan; Wilbrey, Anna; Bahler, Jurg
Present Status of the Theory of Fission of hot Nuclei
Recent progress in the theory of fission of hot nuclei is reported. We discuss in particular the properties of the friction form factor as function of the deformation (and possibly of the temperature) which are necessary to reproduce data concerning fission of hot nuclei and its accompanying light particle and ?-ray emission. Recent theoretical work gives support to a phenomenological friction form factor (proposed some time ago 1)), which is weak for compact shapes and increases on the way to scission. Fission is one of the main decay channels after fusion of two heavy ions. The following discussion is restricted mainly to systems for which Bohr's hypothesis is valid, which states that the formation and decay of the compound nucleus are independent processes, i. e. fission starts only after a completely equilibrated compound
Peter Fröbrich
Total Prompt Energy Release in the Neutron-Induced Fission
This study addresses, for the first time, the total prompt energy release and its components for the fission of 235 U, 238 U, and 239 Pu as a function of the kinetic energy of the neutron inducing the fission. The components are extracted from experimental measurements, where they exist, together with model-dependent calculation, interpolation, and extrapolation. While the components display clear dependencies upon the incident neutron energy, their sums display only weak, yet definite, energy dependencies. Also addressed is the total prompt energy deposition in fission for the same three systems. Results are presented in equation form. New measurements are recommended as a consequence of this study. Key words: Energy release and energy deposition in neutron-induced fission,
D. G. Madland
Identification of Fissionable Materials Using the Tagged Neutron Technique
This summary describes experiments to detect and identify fissionable materials using the tagged neutron technique. The objective of this work is to enhance homeland security capability to find fissionable material that may be smuggled inside shipping boxes, containers, or vehicles. The technique distinguishes depleted uranium from lead, steel, and tungsten. Future work involves optimizing the technique to increase the count rate by many orders of magnitude and to build in the additional capability to image hidden fissionable materials. The tagged neutron approach is very different to other techniques based on neutron die-away or photo-fission. This work builds on the development of the Associated Particle Imaging (API) technique at the Special Technologies Laboratory (STL) [1]. Similar investigations have been performed by teams at the Oak Ridge National Laboratory (ORNL), the Khlopin Radium Institute in Russia, and by the EURITRACK collaboration in the European Union [2,3,4].
R.P. Keegan, J.P. Hurley, J.R. Tinsley, R. Trainham
Fusion-fission reactions with modified Woods-Saxon potential
A modified Woods-Saxon potential model is proposed for a unified description of the entrance channel fusion barrier and the fission barrier of fusion-fission reactions based on the Skyrme energy-density functional approach. The fusion excitation functions of 120 reactions have been systematically studied. The fusion (capture) cross sections are well described with the calculated potential and an empirical barrier distribution. Incorporating a statistical model (HIVAP code) for describing the decay of the compound nucleus, the evaporation residue (and fission) cross sections of 51 fusion-fission reactions have been systematically investigated. Optimal values of some key parameters of the HIVAP code are obtained based on the experimental data of these reactions. The experimental data are reasonably well reproduced by the calculated results. The upper and lower confidence limits of the systematic errors of the calculated results are given.
Ning Wang; Kai Zhao; Werner Scheid; Xizhen Wu
A process is given for determining the neutronic purity of fissionable material by the so-called shotgun test. The effect of a standard neutron absorber of known characteristics and amounts on a neutronic field also of known characteristics is measured and compared with the effect which the impurities derived from a known quantity of fissionable material has on the same neutronic field. The two readings are then made the basis of calculation from which the amount of impurities can be computed.
Fermi, E.; Anderson, H.L.
Fission and Nuclear Liquid-Gas Phase Transition
The temperature dependence of the liquid-drop fission barrier is considered, the critical temperature for the liquid-gas phase transition in nuclear matter being a parameter. Experimental and calculated data on the fission probability are compared for highly excited $^{188}$Os. The calculations have been made in the framework of the statistical model. It is concluded that the critical temperature for the nuclear liquid--gas phase transition is higher than 16 MeV.
E. A. Cherepanov; V. A. Karnaukhov
On the rearrangement time of the fission reaction
The rearrangement time \\Deltat of the fission reaction can be extracted from the full-width at half maximum (f.w.h.m.) of the isotopic distributions of fission fragments if this width is attributed to an uncertainty \\DeltaN in the neutron-number N of the fragment; then the energy-time uncertainty relation leads to \\Deltat = 0.17 yoctosecond.
G. Mouze; C. Ythier
Right-Left Asymmetry of Radiation from Fission
The effect of the right-left asymmetry is considered in the predicted earlier electric dipole radiation from fission fragments arising due to the Strutinski-Denisov induced polarisation mechanism. The magnitude of the asymmetry parameter is on the level of 10^-3. That is in agreement with the recent experimental data on the radiative ROT effect in ^{235}U fission induced by cold polarised neutrons.
Calculation of fission observables through event-by-event simulation
The increased interest in more exclusive fission observables has demanded more detailed models. We present here a new computational model, FREYA, that aims to meet this need by producing large samples of complete fission events from which any observable of interest can then be extracted consistently, including arbitrary correlations. The various model assumptions are described and the potential utility of the model is illustrated by means of several novel correlation observables.
J. Randrup; R. Vogt
Recent progress in the theory of fission of hot nuclei is reported. We discuss in particular the properties of the friction formfactor as function of the deformation (and possibly of the temperature) which are necessary to reproduce data concerning fission of hot nuclei and its accompanying light particle and $\\gamma$-ray emission. Recent theoretical work gives support to a phenomenological friction form factor (proposed some time ago), which is weak for compact shapes and increases on the way to scission.
P. Fröbrich
Evaluation and compilation of fission product yields 1993
This document is the latest in a series of compilations of fission yield data. Fission yield measurements reported in the open literature and calculated charge distributions have been used to produce a recommended set of yields for the fission products. The original data with reference sources, and the recommended yields axe presented in tabular form. These include many nuclides which fission by neutrons at several energies. These energies include thermal energies (T), fission spectrum energies (F), 14 meV High Energy (H or HE), and spontaneous fission (S), in six sets of ten each. Set A includes U235T, U235F, U235HE, U238F, U238HE, Pu239T, Pu239F, Pu241T, U233T, Th232F. Set B includes U233F, U233HE, U236F, Pu239H, Pu240F, Pu241F, Pu242F, Th232H, Np237F, Cf252S. Set C includes U234F, U237F, Pu240H, U234HE, U236HE, Pu238F, Am241F, Am243F, Np238F, Cm242F. Set D includes Th227T, Th229T, Pa231F, Am241T, Am241H, Am242MT, Cm245T, Cf249T, Cf251T, Es254T. Set E includes Cf250S, Cm244S, Cm248S, Es253S, Fm254S, Fm255T, Fm256S, Np237H, U232T, U238S. Set F includes Cm243T, Cm246S, Cm243F, Cm244F, Cm246F, Cm248F, Pu242H, Np237T, Pu240T, and Pu242T to complete fission product yield evaluations for 60 fissioning systems in all. This report also serves as the primary documentation for the second evaluation of yields in ENDF/B-VI released in 1993.
England, T.R.; Rider, B.F.
Method to calibrate fission chambers in Campbelling mode
Fission chambers are neutron detectors which are widely used to instrument experimental reactors such as material testing reactors or zero power reactors. In the presence of a high level mixed gamma and neutron flux, fission chambers can be operated in Campbelling mode (also known as 'fluctuation mode' or 'mean square voltage mode') to provide reliable and precise neutron related measurements. Fission chamber calibration in Campbelling mode (in terms of neutron flux) is usually done empirically using a calibrated reference detector. A major drawback of this method is that calibration measurements have to be performed in a neutron environment very similar to the one in which the calibrated detector will be used afterwards. What we propose here is a different approach based on characterizing the fission chamber response in terms of fission rate. This way, the detector calibration coefficient is independent from the neutron spectrum and can be determined prior to the experiment. The fissile deposit response to the neutron spectrum can then be assessed independently by other means (experimental or numerical). In this paper, the response of CEA made miniature fission chambers in Campbelling mode is studied. We use a theoretical model of the signal to calculate the calibration coefficient. Input parameters of the model come from statistical distribution of individual pulses. Supporting measurements have been made in the CEA Cadarache zero power reactor MINERVE. Results are compared to an empirical Campbelling mode calibration.
Benoit Geslot; Troy C. Unruh; Philippe Filliatre; Christian Jammes; Jacques Di Salvo; Stéphane Bréaud; Jean-François Villard
Systematic Study of Fission Barriers of Excited Superheavy Nuclei
A systematic study of fission-barrier dependence on excitation energy has been performed using the self-consistent finite-temperature Hartree-Fock+BCS (FT-HF+BCS) formalism with the SkM* Skyrme energy density functional. The calculations have been carried out for even-even superheavy nuclei with Z ranging between 110 and 124. For an accurate description of fission pathways, the effects of triaxial and reflection-asymmetric degrees of freedom have been fully incorporated. Our survey demonstrates that the dependence of isentropic fission barriers on excitation energy changes rapidly with particle number, pointing to the importance of shell effects even at large excitation energies characteristic of compound nuclei. The fastest decrease of fission barriers with excitation energy is predicted for deformed nuclei around N=164 and spherical nuclei around N=184 that are strongly stabilized by ground-state shell effects. For nuclei 240Pu and 256Fm, which exhibit asymmetric spontaneous fission, our calculations predict a transition to symmetric fission at high excitation energies due to the thermal quenching of static reflection asymmetric deformations.
J. A. Sheikh; W. Nazarewicz; J. C. Pei
Radiochemically determined mass-yield curves are given for the fission of U/sup 235/ and U/sup 238/ by l4.7-Mev neutrons. Symmetric and to a less extent, very asymmetric modes of fission are more probable at that energy than in thermal fission. Yields of four fission products from the fission of U/sup 235/ have been measured as a function of neutron energy in the range thermal to 14 Mev. The yields of eleven masses have been measured from the fission of Np/sup 237/ by degraded fission spectrum neutrons. The mass-yield curve is similar to that from the thermal fission of Pu/sup 239/ with a ratio of peak to valley yields of approximately 175. Relative yields of one peak fission product and four valley fission products have been determdned under the following conditions: fission of U/sup 235/ and Pu/sup 239/ with thermal neutrons; fission of U/sup 235/ Pu/sup 239/ and U/sup 238/ with fission spectrum neutrons; and fission of U//sup 235/ and Pu/sup 239/ with the intermediate neutron spectrum at the center of the Los Alamos Fast Reactor. Absolute yields of Moss have been determined from the fission of U/sup 235/,Pu/sup 239/ with thermal neutrons. (auth)
Ford, G.P.; Gilmore, J.S.; Ames, D.P.; Balagna, J.P.; Barnes, J.W.; Comstock, A.A.; Cowan, G.A.; Elkin, P.B.; Hoffman, D.C.; Knobeloch, G.W.; Lang, E.J.; Melnick, M.A.; Minkkinen, C.O.; Pollock, B.D.; Sattizshn, J.E.; Stanley, C.W.; Warren, B.
Description of true and delayed ternary nuclear fission accompanied by the emission of various third particles
The mechanisms and the features of the main types of nuclear ternary fission (that is, true ternary fission, in which a third particle is emitted before the rupture of the fissioning nucleus into fragments, and delayed ternary fission, in which a third particle is emitted from fission fragments going apart) are investigated within quantum-mechanical fission theory. The features of T-odd asymmetry in true ternary nuclear fission induced by cold polarized neutrons are investigated for the cases where alpha particles, prescission neutrons, and photons appear as third particles emitted by fissioning nuclei, the Coriolis interaction of the spin of the polarized fissioning nucleus with the spin of the third particle and the interference between the fission amplitudes for neutron resonances excited in the fissioning nucleus in the case of projectile-neutron capture being taken into account. For the cases where third particles emitted by fission fragments are evaporated neutrons or photons, T-odd asymmetries in delayed ternary nuclear fission induced by cold polarized neutrons are analyzed with allowance for the mechanism of pumping of large fission-fragment spins oriented orthogonally to the fragment-emission direction and with allowance for the interference between the fission amplitudes for neutron resonances.
Kadmensky, S. G., E-mail: email@example.com; Kadmensky, S. S.; Lyubashevsky, D. E. [Voronezh State University (Russian Federation)
Cooperative Modeling and Design History Tracking Using Design Tracking Matrix
This thesis suggests a new framework for cooperative modeling which supports concurrency design protocol with a design history tracking function. The proposed framework allows designers to work together while eliminating design conflicts and redundancies, and preventing infeasible designs. This framework provides methods to track optimal design path and redundant design history in the overall design process. This cooperative modeling architecture consists of a modeling server and voxel-based multi-client design tool. Design change among server and multiple clients are executed using the proposed concurrency design protocol. The design steps are tracked and analyzed using Design Tracking Graph and Design Tracking Matrix (DTM), which provide a design data exchange algorithm allowing seamless integration of design modifications between participating designers. This framework can be used for effective cooperative modeling, and helps identify and eliminate conflicts and minimize delay. The proposed algorithm supports effective cooperative design functions. First, it provides a method to obtain the optimal design path which can be stored in a design library and utilized in the future design. Second, it helps capture modeling pattern which can be used for analyzing designer's performance. Finally, obtained redundancies can be used to evaluate designer?s design efficiency.
Kim, Jonghyun
Description of Induced Nuclear Fission with Skyrme Energy Functionals: I. Static Potential Energy Surfaces and Fission Fragment Properties
Eighty years after its experimental discovery, a microscopic description of induced nuclear fission based solely on the interactions between neutrons and protons and quantum many-body methods still poses formidable challenges. The goal of this paper is to contribute to the development of a predictive microscopic framework for the accurate calculation of static properties of fission fragments for hot fission and thermal or slow neutrons. To this end, we focus on the 239Pu(n,f) reaction and employ nuclear density functional theory with Skyrme energy densities. Potential energy surfaces are computed at the Hartree-Fock-Bogoliubov approximation with up to five collective variables. We find that the triaxial degree of freedom plays an important role, both near the fission barrier and at scission. The impact of the parameterization of the Skyrme energy density on deformation properties from the ground-state up to scission is also quantified. We introduce a general template for the detailed description of fission fragment properties. It is based on the careful analysis of the scission point, using both advanced topological methods and recently proposed quantum many-body techniques. We conclude that an accurate prediction of fission fragment properties at low incident neutron energies, although technologically demanding, should be within the reach of current nuclear density functional theory.
N. Schunck; D. Duke; H. Carr; A. Knoll
Background for Terrestrial Antineutrino Investigations: Radionuclide Distribution, Georeactor Fission Events, and Boundary Conditions on Fission Power Production
Estimated masses of fissioning and non-fissioning radioactive elements and their respective distributions within the Earth are presented, based upon the fundamental identity of the components of the interior 82% of the Earth, the endo-Earth, with corresponding components of the Abee enstatite chondrite meteorite. Within limits of existing data, the following generalizations concerning the endo-Earth radionuclides can be made: (1) Most of the K-40 may be expected to exist in combination with oxygen in the silicates of the lower mantle, perhaps being confined to the upper region of the lower mantle where it transitions to the upper mantle; (2) Uranium may be expected to exist at the center of the Earth where it may undergo self-sustaining nuclear fission chain reactions, but there is a possibility that some non-fissioning uranium may be found scattered diffusely within the core floaters which are composed of CaS and MgS; and, (3) Thorium may be expected to occur within the core floaters at the core-mantle boundary, although its presence as well at the center of the Earth cannot be ruled out. Results of nuclear georeactor numerical simulations show: (1) The maximum constant nuclear fission power level is 30 terawatts; (2) U-235 comprises 76 percent of present-day georeactor fission, U-238 comprises 23 percent; and, (3) Thorium can neither be fuel nor converted into fuel for the georeactor.
J. Marvin Herndon; Dennis A. Edgerley
Towards front-tracking based on conservation in two space dimensions III, tracking interfaces
This is the third paper in the series of our conservative front-tracking method. In this paper, we describe how our method tracks fluid interfaces in multi-fluid flows. Two important ingredients in our conservative front-tracking method in tracking fluid ... Keywords: Conservative front-tracking, Fluid interface, Numerical surface dissipation, Velocity and pressure equilibrium
Mohammed Aman Ullah, Wenbin Gao, De-Kang Mao
TRISO Fuel Performance: Modeling, Integration into Mainstream Design Studies, and Application to a Thorium-fueled Fusion-Fission Hybrid Blanket
generation [1, 5, 6, 7]. Nuclear fission energy systems thatgeneration from nuclear fission plants may in fact need toof a Hybrid Fusion-Fission Nuclear Energy System. " Thesis.
Powers, Jeffrey
Response of fission yeast to toxic cations involves cooperative action of the stress-activated protein kinase Spc1/Sty1 and the Hal4 protein kinase
1993. Experiments with Fission Yeast. A laboratory coursetranscriptional responses of fission yeast to environmentalWhitehall. 2002. Role of fission yeast Tup1-like repressors
Wang, L Y; Shimada, K; Morishita, M; Shiozaki, Kazuhiro
Tracking features and exploring their temporal dynamics can aid scientists in identifying interesting time intervals in a simulation and serve as basis for performing quantitative analyses of temporal phenomena. In this paper, we develop a novel approach for tracking subsets of isosurfaces, such as burning regions in simulated flames, which are defined as areas of high fuel consumption on a temperature isosurface. Tracking such regions as they merge and split over time can provide important insights into the impact of turbulence on the combustion process. However, the convoluted nature of the temperature isosurface and its rapid movement make this analysis particularly challenging. Our approach tracks burning regions by extracting a temperature isovolume from the four-dimensional space-time temperature field. It then obtains isosurfaces for the original simulation time steps and labels individual connected 'burning' regions based on the local fuel consumption value. Based on this information, a boundary surface between burning and non-burning regions is constructed. The Reeb graph of this boundary surface is the tracking graph for burning regions.
Weber, Gunther H.; Bremer, Peer-Timo; Day, Marcus S.; Bell, John B.; Pascucci, Valerio
Effect of transients in nuclear fission on multiplicity of prescission neutrons
Transients in the fission of highly excited nuclei are studied in the framework of the Langevin equation. Time-dependent fission widths are calculated which show that after the initial transients, a steady flow towards the scission point is established not only for nuclei which have fission barriers but also for nuclei which have no fission barrier. It is shown from a comparison of the transient time and the fission life time that fission changes from a diffusive to a transient dominated process over a certain transition region as a function of the spin of the fissioning nucleus. Multiplicities of prescission neutrons are calculated in a statistical model with as well as without a single swoop description of fission and they are found to differ in the transition region. We however find that the difference is marginal and hence a single swoop picture of fission though not strictly valid in the transition region can still be used in the statistical model calculations.
Insights On The Thermal History Of The Valles Caldera, New Mexico...
icon Twitter icon Insights On The Thermal History Of The Valles Caldera, New Mexico- Evidence From Zircon Fission-Track Analysis Jump to: navigation, search GEOTHERMAL...
Neutron source capability assessment for cumulative fission yields measurements
A recent analysis of high-quality cumulative fission yields data for Pu-239 published in the peer-reviewed literature showed that the quoted experimental uncertainties do not allow a clear statement on how the fission yields vary as a function of energy. [Prussin2009] To make such a statement requires a set of experiments with well 'controlled' and understood sources of experimental errors to reduce uncertainties as low as possible, ideally in the 1 to 2% range. The Inter Laboratory Working Group (ILWOG) determined that Directed Stockpile Work (DSW) would benefit from an experimental program with the stated goal to reduce the measurement uncertainties significantly in order to make a definitive statement of the relationship of energy dependence to the cumulative fission yields. Following recent discussions between Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL), there is a renewed interest in developing a concerted experimental program to measure fission yields in a neutron energy range from thermal energy (0.025 eV) to 14 MeV with an emphasis on discrete energies from 0.5 to 4 MeV. Ideally, fission yields would be measured at single energies, however, in practice there are only 'quasi-monoenergetic' neutrons sources of finite width. This report outlines a capability assessment as of June 2011 of available neutron sources that could be used as part of a concerted experimental program to measure cumulative fission yields. In a framework of international collaborations, capabilities available in the United States, at the Atomic Weapons Establishment (AWE) in the United Kingdom and at the Commissariat Energie Atomique (CEA) in France are listed. There is a need to develop an experimental program that will reduce the measurement uncertainties significantly in order to make a definitive statement of the relationship of energy dependence to the cumulative fission yields. Fission and monoenergetic neutron sources are available that could support these fission yield experiments in the US, as well as at AWE and CEA. Considerations that will impact the final choice of experimental venues are: (1) Availability during the timeframe of interest; (2) Ability to accommodate special nuclear materials; (3) Cost; (4) Availability of counting facilities; and (5) Expected experimental uncertainties.
Descalle, M A; Dekin, W; Kenneally, J
Kinetic energy deficit in the symmetric fission of /sup 259/Md. [Light particle emission in /sup 256/Fm fission
The fragment energies of about 725 coincidence events have now been observed in the spontaneous fission (SF) decay of 105-min /sup 259/Md since its discovery in 1977. The fission of /sup 259/Md is characterized by a symmetric mass distribution, similar to those of /sup 258/Fm and /sup 259/Fm, but with a broad total kinetic energy (anti TKE) distribution which peaks at about 195 MeV, in contrast to those of /sup 258/Fm and /sup 259/Fm, for which the anti TKE is about 240 MeV. This kinetic energy deficit, approx. 40 MeV, has been postulated to be due to the emission of hydrogen-like particles by /sup 259/Md at the scission point in a large fraction of the fissions, leaving the residual fissioning nucleus with 100 protons. The residual nucleus would then be able to divide into two ultrastable tin-like fission fragments, but with less kinetic energy than that observed in the SF of /sup 258/Fm and /sup 259/Fm, because of binding-energy losses and a reduction in the Coulomb repulsion of the major fragments. To test this hypothesis, counter-telescope experiments aimed at detecting and identifying these light particles were performed. In 439 SF events 3 + 3 protons of the appropriate energy were observed, too few to account for the kinetic energy deficit in the fission of /sup 259/Md. There seems to be no explanation for this problem within the framework of current fission theory. These results are discussed along with preliminary measurements of light-particle emission in the SF of /sup 256/Fm. 5 figures.
Hulet, E.K.; Wild, J.F.; Lougheed, R.W.; Baisden, P.A.; Dougan, R.J.; Mustafa, M.G.
Spontaneous Muon Emission during Fission, a New Nuclear Radioactivity
In this paper the essential theoretical predictions for the nuclear muonic radioactivity are presented by using a special fission-like model similar with that used in description of the pionic emission during fission. Hence, a fission-like model for the muonic radioactivity takes into account the essential degree of freedom of the system: muon-fissility, muon-fission barrier height, etc. Using this model it was shown that most of the SHE-nuclei lie in the region where the muonic fissility parameters attain their limiting value X=1. Hence, the SHE-region is characterized by the absence of a classical barrier toward spontaneous muon and pion emissions. Numerical estimations on the yields for the natural muonic radioactivities of the transuranium elements as well numerical values for barrier heights are given only for even-even parent nuclei. Some experimental results from LCP-identification emission spectrum are reviewed. Also, the experimental results obtained by Khryachkov et al, using new spectrometer for investigation of ternary nuclear fission, are presented. The OPERA-experiment proposed to perform search for muonic radioactivity from lead nuclei, in the low background conditions offered by the Gran Sasso underground Laboratory (LNGS), is discussed.
D. B. Ion; M. L. D. Ion; Reveica Ion-Mihai
Fission gas release restrictor for breached fuel rod
In the event of a breach in the cladding of a rod in an operating liquid metal fast breeder reactor, the rapid release of high-pressure gas from the fission gas plenum may result in a gas blanketing of the breached rod and rods adjacent thereto which impairs the heat transfer to the liquid metal coolant. In order to control the release rate of fission gas in the event of a breached rod, the substantial portion of the conventional fission gas plenum is formed as a gas bottle means which includes a gas pervious means in a small portion thereof. During normal reactor operation, as the fission gas pressure gradually increases, the gas pressure interiorly of and exteriorly of the gas bottle means equalizes. In the event of a breach in the cladding, the gas pervious means in the gas bottle means constitutes a sufficient restriction to the rapid flow of gas therethrough that under maximum design pressure differential conditions, the fission gas flow through the breach will not significantly reduce the heat transfer from the affected rod and adjacent rods to the liquid metal heat transfer fluid flowing therebetween.
Kadambi, N. Prasad (Gaithersburg, MD); Tilbrook, Roger W. (Monroeville, PA); Spencer, Daniel R. (Unity Twp., PA); Schwallie, Ambrose L. (Greensburg, PA)
Pom1 DYRK regulates localization of the Rga4 GAP to ensure bipolar activation of Cdc42 in fission yeast
in polarized cell growth in fission yeast. J Cell Sci 115,genes nda2 and nda3 of the fission yeast Schizosaccharomycesalpha 2- tubulin genes as fission yeast polarity mutants.
Tatebe, Hisashi; Nakano, Kentaro; Maximo, Rachel; Shiozaki, Kazuhiro
The fission yeast stress MAPK cascade regulates the pmp3+ gene that encodes a highly conserved plasma membrane protein.
transcription factor in fission yeast. Genes Dev. Degols, G.stress-activated kinase in fission yeast. Genes Dev. 12,MAP kinase pathway in fission yeast. Genes Dev. 10, 2289-
Wang, Ling-yu; Shiozaki, Kazuhiro
The fission yeast stress MAPK cascade regulates the pmp3(+) gene that encodes a highly conserved plasma membrane protein
Solar photovoltaic panels tracking system
This research project concentrates on the design and control of a two-degrees-of-freedom orientation system for the photovoltaic solar panels in sunny regions which are considered very rich in solar energy. A brief background on the sun path and behavior ... Keywords: altitude, azimuth, closed-loop control, open-loop control, orientation, sensor, solar photovoltaic panels, solar tracking
Ahmed Abu Hanieh
Toward Designed Singlet Fission: Electronic States and Photophysics of
Designed Singlet Fission: Electronic States and Photophysics of Designed Singlet Fission: Electronic States and Photophysics of 1,3-Diphenylisobenzofuran Andrew F. Schwerin, Justin C. Johnson, Millicent B. Smith, Paiboon Sreearunothai, Duska Popovic, Jiri Cerny, Zdenek Havlas, Irina Paci, Akin Akdag, Matthew K. MacLeod, Xudong Chen, Donald E. David, Mark A. Ratner, John R. Miller, Arthur J. Nozik and Josef Michl J. Phys. Chem. A 114, 1457-1473 (2010). [Find paper at ACS Publications] Abstract: Single crystal molecular structure and solution photophysical properties are reported for 1,3-diphenylisobenzofuran (1), of interest as a model compound in studies of singlet fission. For the ground state of 1 and of its radical cation (1+*) and anion (1-*), we report the UV-visible absorption spectra, and for neutral 1, also the magnetic
Estimates of fission yields in nuclear criticality excursions
There is a need for computer simulation of hypothetical criticality excursions involving significant quantities of fissionable materials, especially in fissile aqueous system. The need arises due to the requirements for the emergency planning of facilities where the fissionable materials are handled, processed, or stored; and the regulatory requirements associated with facility operation or conversion. It is proposed here that a data base of fission yeilds for critical experiments and known accidents (both aqueous and solid) should be generated by using existing or new computer codes. The success in compiling this data base would provide useful source-terms for criticality excursions, realistic estimates of emergency-response boundary, as well as a replacement for the ``rule-of-thumb`` or ``bounding`` method. 10 refs.
Choi, J.S. [Lawrence Livermore National Lab., CA (United States); Thompson, J.W. [Atlantic Nuclear Services, Ottawa, ON (Canada); Reed, R. [Westinghouse Savannah River Co., Aiken, SC (United States)
Sputtering yield of Pu bombarded by fission Fragments from Cf
We present results on the yield of sputtering of Pu atoms from a Pu foil, bombarded by fission fragments from a {sup 252}Cf source in transmission geometry. We have found the number of Pu atoms/incoming fission fragments ejected to be 63 {+-} 1. In addition, we show measurements of the sputtering yield as a function of distance from the central axis, which can be understood as an angular distribution of the yield. The results are quite surprising in light of the fact that the Pu foil is several times the thickness of the range of fission fragment particles in Pu. This indicates that models like the binary collision model are not sufficient to explain this behavior.
Danagoulian, Areg [Los Alamos National Laboratory; Klein, Andreas [Los Alamos National Laboratory; Mcneil, Wendy V [Los Alamos National Laboratory; Yuan, Vincent W [Los Alamos National Laboratory
Microscopic description of Cf-252 cold fission yields
We investigate the cold fission of 252Cf within the two center shell model to compute the potential energy surface. The fission yields are estimated by using the semiclassical penetration approach. It turns out that the inner cold valley of the total potential energy is strongly connected with Z=50 magic number. The agreement with experimental values is very much improved only by considering mass and charge asymmetry degrees of freedom. Thus, indeed cold fission of 252Cf is a Sn-like radioactivity, related the other two "magic radioactivities", namely alpha-decay and heavy-cluster decay, called also Pb-like radioactivity. This calculation provides the necessary theoretical confidence to estimate the penetration cross section in producing superheavy nuclei, by using the inverse fusion process.
Mirea, M; Sandulescu, A
M. Mirea; D. S. Delion; A. Sandulescu
Employee Concerns Tracking System, PIA, Bechtel Jacobs Company...
Concerns Tracking System, PIA, Bechtel Jacobs Company, LLC Employee Concerns Tracking System, PIA, Bechtel Jacobs Company, LLC Employee Concerns Tracking System, PIA, Bechtel...
PIA - Foreign Access Central Tracking System (FACTS) | Department...
Access Central Tracking System (FACTS) PIA - Foreign Access Central Tracking System (FACTS) PIA - Foreign Access Central Tracking System (FACTS) PIA - Foreign Access Central...
PIA - Energy Inspector General Project Tracking System (EIGPT...
Inspector General Project Tracking System (EIGPT) PIA - Energy Inspector General Project Tracking System (EIGPT) PIA - Energy Inspector General Project Tracking System (EIGPT) PIA...
Particle Tracking and Simulation on the .NET Framework
to EPAC 2006 PARTICLE TRACKING AND SIMULATION ON THE .NET94720, USA Abstract Particle tracking and simulation studieswas measured using three tracking programs on a simplified
Nishimura, Hiroshi; Scarvie, Tom
Tracking and analysis of C. elegans behavior using machine vision
and W.R. Schafer, Automatic tracking, feature extraction andapproach to segmenting and tracking people in a clutteredbased particle filtering for tracking a variable number of
Huang, Kuang Man
Extracting longitudinal shower development information from crystal calorimetry plus tracking
crystal calorimetry plus tracking D.N. Brown a , J. Ilic b ,calorimeter by using tracking information. Ourgood three- dimensional tracking resolution of B A B AR ,
Brown, D.N.
PIA - Correspondence and Action Tracking System (CATS) | Department...
Correspondence and Action Tracking System (CATS) PIA - Correspondence and Action Tracking System (CATS) PIA - Correspondence and Action Tracking System (CATS) PIA - Correspondence...
On numerical relations playing a role in nuclear fission
The key numbers useful for describing the fission process are the mass number of the primordial cluster of the fissioning system and the magic mass numbers 82 and 126 of the nascent light and heavy fragments. The mean mass number and the mean atomic number of the light fragments are linked to the mass number and to the atomic number of the primordial cluster by simple relationships. The value 54 of the mean atomic number of the heavy fragments is predicted by the nucleon phase model.
The number of neutrons emitted by individual fragments from U/sup 235/ fission by thermal neutrons was measured using a large detector filled with a liquid organic cadmiumcontaining scintillator. The numbers of prompt neutrons were measured under 4 pi geometry conditions as a function of fragment mass. The excitation energy spent on prompt neutrons was derived on the basis of Weizsacker's semiempirical formula. A sharp asymmetry was noticed in the distribution of excitation energies between heavy and light fragments. The new data do not agree with the Fong statistical fission theory. (tr-auth)
Apalin, V.F.; Dobrynin, Yu.P.; Zakharova, V.P.; Kutikov, I.E.; Mikaelyan, L.A.
Distribution of independent fission-product yields to isomeric states
A simple one-parameter model is presented for calculating the distribution of independent yield strength between ground and isomeric states of primary fission products formed by neutron-induced fission of actinide nuclei. Yield branching ratios are calculated as a function of neutron energy (thermal, fast, and 14-MeV) for 144 nuclides having isomeric states with T/sub 1/2/ greater than or equal to 0.1 s. The results are proposed for use in the ENDF/B-V yield files.
Madland, D.G.; England, T.R.
Development of fission gas swelling and release models for metallic nuclear fuels
Fuel swelling and fission gas generation for fast reactor fuels are of high importance since they are among the main limiting factors in the development of metallic fast reactor fuel. Five new fission gas and swelling ...
Andrews, Nathan Christopher
A Model for Water Factor Measurements With Fission-Neutron Logging...
A Model for Water Factor Measurements With Fission-Neutron Logging Tools (May 1983) A Model for Water Factor Measurements With Fission-Neutron Logging Tools (May 1983) A Model for...
DOE Science Showcase - Fission Theory | OSTI, US Dept of Energy, Office of
Fission Theory Fission Theory A predictive theory of nuclear fission has eluded physicists since 1939. Because understanding the fission process is crucial for many areas of scientific research, including particle systems, the development of carbon-free energy and to national security, much work continues at the Department of Energy (DOE) to understand fission's inherent complexity. Today, scientists are performing new experiments and using both microscopic and macroscopic-microscopic models of fission to help them in this quest. Read more about remarkable advances in the Department's fission theory research In the OSTI Collections: Fission Theory by Dr. William Watson, Physicist, OSTI staff. Image Credit: Los Alamos National Laboratory Additional Links of Interest Office of Nuclear Energy, DOE
Tracking dynamic regions of texture and shape
The tracking of visual phenomena is a problem of fundamental importance in computer vision. Tracks are used in many contexts, including object recognition, classification, camera calibration, and scene understanding. ...
Migdal, Joshua N. (Joshua Nicholas), 1979-
On target tracking with binary proximity sensors
We consider the use of binary proximity sensors for tracking targets. Such sensors provide only 1-bit information regarding a target's presence or absence in their vicinity, albeit with less than 100% reliability. A novel tracking method employing such ...
Wooyoung Kim; Kirill Mechitov; Jeung-Yoon Choi; Soo Ham
Climate Modulation of North Atlantic Hurricane Tracks
The variability of North Atlantic tropical storm and hurricane tracks, and its relationship to climate variability, is explored. Tracks from the North Atlantic hurricane database for the period 1950–2007 are objectively separated into four groups ...
James P. Kossin; Suzana J. Camargo; Matthew Sitkowski
1H, 15N, and 13C chemical shift assignments of neuronal calcium sensor-1 homolog from fission yeast
Keywords NCS Á Ncs1p Á Fission yeast Á Calcium Á EF-hand ÁTakeda K, Ames JB (2004) Fission yeast homolog of neuronal
Lim, Sunghyuk; Ames, James B.
A fission-fusion hybrid reactor in steady-state L-mode tokamak configuration with natural uranium.
??The most prevalent criticism of fission-fusion hybrids is simply that they are too exotic - that they would exacerbate the challenges of both fission and… (more)
Reed, Mark Wilbert
Detecting a Nuclear Fission Reactor at the Center of the Earth
A natural nuclear fission reactor with a power output of 3- 10 terawatt at the center of the earth has been proposed as the energy source of the earth's magnetic field. The proposal can be directly tested by a massive liquid scintillation detector that can detect the signature spectrum of antineutrinos from the geo-reactor as well as the direction of the antineutrino source. Such detectors are now in operation or under construction in Japan/Europe. However, the clarity of both types of measurements may be limited by background from antineutrinos from surface power reactors. Future U. S. detectors, relatively more remote from power reactors, may be more suitable for achieving unambiguous spectral and directional evidence for a 3TW geo-reactor.
R. S. Raghavan
Overview of the TREC 2011 Legal Track
... USF University of Waterloo UW Ursinus College URS Table 1: Organizations participating in the TREC 2011 Legal Track. ...
Development of a Micromegas TPC for Low Energy Heavy Ions Measurement for Nuclear Fission and Astrophysics Applications
Time Projection Chambers are widely used since many years for tracking and identification of charged particles in high energy physics. We present a new R and D project to investigate the feasibility of a Micromegas TPC for low energy heavy ions detection. Two physics cases are relevant for this project. The first is the study of the nuclear fission of actinides by measuring the fission fragments properties (mass, nuclear charge, kinetic energy) that will be performed at different installations and in particular at the NFS facility to be built in the framework of the SPIRAL2 project in GANIL. The second physics case is the study of heavy ion reactions, like ({alpha},{gamma}), ({alpha},p), ({alpha},n) and all the inverse reactions in the energy range between 1.5 and 3 AMeV using both stable and radioactive beams. These reactions have a key role in p process in nuclear astrophysics to explain the synthesis of heavy proton-rich nuclei. Within the project, a large effort is devoted to Monte-Carlo simulations and a detailed benchmark of different simulation codes on the energy loss and range in gas of heavy ions at low energy has been performed. A new approach for simulating the ion charge state evolution in GEANT4 is also presented. Finally, preliminary results of an experimental test campaign on prototype are discussed.
Panebianco, S.; Dore, D.; Giomataris, I.; Papaevangelou, Th.; Vernoud, L. [CEA, Centre de Saclay, Institut de Recherche sur les lois Fondamentales de l' Univers, 91191 Gif-sur-Yvette (France); Axiotis, M.; Fanourakis, G.; Geralis, Th.; Harissopoulos, S.; Lagoyannis, A. [Institute of Nuclear Physics, NCRS ' Demokritos' , 15310 Aghia Paraskevi, Athens (Greece)
Fusion-Fission Hybrid Using a D-D Cylindrical Inertial Electrostatic Confinement (IEC) Driver
George H. Miley; Bradley Boyer
Direct Energy Conversion Fission Reactor for the period December 1, 1999 through February 29, 2000
OAK B135 Direct Energy Conversion Fission Reactor for the period December 1, 1999 through February 29, 2000
Brown, L.C.
Basics of Fusion-Fission Research Facility (FFRF) as a Fusion Neutron Source
Leonid E. Zakharov
Methods to Collect, Compile, and Analyze Observed Short-lived Fission Product Gamma Data
A unique set of fission product gamma spectra was collected at short times (4 minutes to 1 week) on various fissionable materials. Gamma spectra were collected from the neutron-induced fission of uranium, neptunium, and plutonium isotopes at thermal, epithermal, fission spectrum, and 14-MeV neutron energies. This report describes the experimental methods used to produce and collect the gamma data, defines the experimental parameters for each method, and demonstrates the consistency of the measurements.
Finn, Erin C.; Metz, Lori A.; Payne, Rosara F.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Pierson, Bruce D.; Ellis, Tere A.
The Project of Fusion-Fission Hybrid Energy Reactor in China
Maosheng Li; Rong Liu; Xueming Shi; Weiwei Yi; Yaosong Shen; Xianjue Peng
Future risks of satellite-based tracking
This study finds out if in the future, some special risks concerning satellite-based tracking and navigation occur. To find out possible future risks, future research methods such as scenarios were being used. Forecasting the future is impossible, but ... Keywords: future research, risk management, satellite-base tracking, satellite-based navigation, tracking
Miikka Ohisalo; Otto Tiuri; Tatu Urpila; Jyri Rajamäki
A medical tracking system for contrast media
Contrast media is a kind of chemical substance used to improve the image quality of Computed Tomography. However, due to its high speed of injection, emergencies (such as capillary hemorrhage) always exist. In view of this problem, a video object tracking ... Keywords: color histogram, mean shift algorithm, tracking, visual tracking
Chuan Dai; Zhelong Wang; Hongyu Zhao
Simultaneous Localization, Mapping and Moving Object Tracking
Simultaneous localization, mapping and moving object tracking (SLAMMOT) involves both simultaneous localization and mapping (SLAM) in dynamic environments and detecting and tracking these dynamic objects. In this paper, a mathematical framework is ... Keywords: detection, localization, mapping, mobile robotics, robotic perception, tracking
Chieh-Chih Wang; Charles Thorpe; Sebastian Thrun; Martial Hebert; Hugh Durrant-Whyte
Indoor tracking of laboratory mice via an rfid-tracking framework
In this paper a solution for tracking of laboratory mice in an indoor semi natural environment based on RIFD-Technology is presented. A tracking framework is built where combined sensors identify and track the mice continuously 24 hours a day and 7 days ... Keywords: RFID, localization, tracking
Mareike Kritzler; Stephanie Jabs; Philipp Kegel; Antonio Krüger
NEANDC specialists meeting on yields and decay data of fission product nuclides
Separate abstracts were prepared for the 29 papers presented. Workshop reports on decay heat, fission yields, beta- and gamma-ray spectroscopy, and delayed neutrons are included. An appendix contains a survey of the most recent compilations and evaluations containing fission product yield, fission product decay data, and delayed neutron yield information. (WHK)
Chrien, R.E.; Burrows, T.W. (eds.)
Quantum mechanical method of fragment's angular and energy distribution calculation for binary and ternary fission
In the framework of quantum-mechanical fission theory, the method of calculation for partial fission width amplitudes and asymptotic behavior of the fissile nucleus wave function with strong channel coupling taken into account has been suggested. The method allows one to solve the calculation problem of angular and energy distribution countation for binary and ternary fission.
Kadmensky, S. G., E-mail: firstname.lastname@example.com; Titova, L. V.; Pen'kov, N. V. [Voronezh State University (Russian Federation)
Light ternary fission products: probabilities and charge distributions. [Reviews, data systematics
A survey was made of experimental information pertinent to the probability of ternary fission and the charge distribution of the light ternary fission products. A new prescription is presented for the ternary fission probability as a function of incident particle energy and certain compound nucleus properties. Based upon systematics, a method for obtaining charge distributions of the light ternary products is presented.
Madland, D.G.; Stewart, L.
A description of heavy ion induced fission based on diffusion model
In this talk a review on our recent work on fission theory from point of view of diffusion process is presented. The transient phenomena of fission rate are revealed and studied carefully. By comparison of the fission rate calculated both at the saddle and seission points
Wu Xizhen; Feng Renfa; Bao Jingdong; Sun Zemin; Zhuo Yizhong
Plenary II -- Track Safety Standards
TSS 2001 A TSS 2001 A V 1.0 1 Federal Railroad Administration Track Safety Standards (TSS) 49 CFR Part 213 Subpart A - General Excepted Track & Classes 1 - 5 Overview TSS 2001 A V 1.0 2 Presentation Notes * This presentation is intended to provide guidance in broad terms. It is not intended to serve as a complete explanation of the regulations or as a substitute for application of the regulations to specific facts. * With the exception of definitions, each section shown in this presentation are brief summaries of the regulation text. User must consult the complete regulation documentation when necessary. * This presentation is based on the Final Rule published in the Federal Register June 22, 1998, Vol. 63, No. 119, [Docket RST-90-1, Notice 8] effective Sept. 21, 1998 and
Keeping track of the damage
News Archives: News Archives: 2012 | 2011 | 2010 | 2009 2008 | 2007 | 2006 | 2005 2004 | 2003 | 2002 | 2001 2000 Subscribe to APS News rss feed Keeping track of the damage Scientists resolve long-standing mystery of ion-solid interactions Reprinted with kind permission from ScienceWise - Science Magazine of the Australian National University JANUARY 27, 2009 Bookmark and Share Dr. Patrick Kluth and Claudia Schnohr. Silica (silicon dioxide) is the most abundant mineral in the earth's crust and consequently is a core component in many rocks. It's quite common for such rocks to also contain natural traces of materials like uranium that undergo slow radioactive decay. This radioactivity produces energetic particles that smash through the surrounding silica creating tracks of localized damage in their wake.
Validation of MCNPX-PoliMi Fission Models
We present new results on the measurement of correlated, outgoing neutrons from spontaneous fission events in a Cf-252 source. 16 EJ-309 liquid scintillation detectors are used to measure neutron-neutron correlations for various detector angles. Anisotropy in neutron emission is observed. The results are compared to MCNPX-PoliMi simulations and good agreement is observed.
S. A. Pozzi; S. D. Clarke; W. Walsh; E. C. Miller; J. Dolan; M. Flaska; B. M. Wieger; A. Enqvist; E. Padovani; J. K. Mattingly; D. L. Chichester; P. Peerani
Pionic Radioactivity as New Mode of Nuclear Fission
In this paper a short review of the theoretical problems of the pionic radioactivity as a new nuclear mode is presented. The essential theoretical and experimental results obtained in the 25 years from the prediction of the nuclear pionic radioactivity are reviewed. Using the fission-like model it was shown that most of the SHE-nuclei lie in the region where the pionic fissility parameters attain their limiting value X=1 (see Fig.2-3). Hence, the SHE-region is characterized by the absence of a classical barrier toward spontaneous pion emission. Consequently, both decay modes, the pionic fission and the spontaneous fission of SHE nuclides, essentially will be determined only by shell effects. Then, it was seen that the usual predicted SHE-island of stability around the double magic nucleus 298-[114], which is not confirmed experimentally, can be explained by the dominant pionic radioactivity of the SHE-nuclei from this region. The bimodal symmetric (see Figs. 5ab) as well as, the supergiant radioactive halos (see Fig. 6) as two important signature of the nuclear pionic fission are evidentiated.
Reactor as a Source of Antineutrinos: Thermal Fission Energy
Deeper insight into the features of a reactor as a source of antineutrinos is required for making further advances in studying the fundamental properties of the neutrino. The relationship between the thermal power of a reactor and the rate of the chain fission reaction in its core is analyzed.
V. Kopeikin; L. Mikaelyan; V. Sinev
Title: WPEC Subgroup Proposal Prompt Photon Production from Fission Products
In a typical nuclear reactor some 10-12 % of heating comes from the energy deposited by gamma rays. The major photon production sources (equal proportions) are:- prompt neutron induced fission, capture of prompt neutrons, and the decay of fission plus activation daughter products. The photons penetrate some distance from their birth and can cause some 80-90 % of heating in non-fissile regions. This can lead to distortion of control rods and chemical damage in moderators, e.g. enhancing graphite erosion rate. There is considerable interest in extending fuel life (deep burn) and this in turn leads to more higher actinides and more FISSION PRODUCTS (nuclides with Z=35-70). A survey (of JEFF3.0, ENDF/B-VIr8 and JENDL3.3) in 2003 indicated very few modern evaluations in the mass range of fission products contain gamma source data. Where data are present they are often old and incomplete. At the completion of WPEC sub-group 23, a comprehensive and validated file of neutron cross sections will be ready for inclusion in modern libraries. This would form an ideal base that could be extended to include source information for production of prompt gammas.
Short Justification For A Subgroup; Jeff C J Dean
Downstream Behavior of Volatile Iodine, Cesium, and Tellurium Fission Products
A better understanding of how iodine, cesium, and tellurium fission products deposit on primary reactor components during a degraded core accident can help utility analysts improve computer codes that model product behavior. The mathematical model developed in this study predicts the behavior of deposited products vaporized or revaporized by self-heating in a reactor accident.
Fission Cycling in a Supernova r-process
Recent halo star abundance observations exhibit an important feature of consequence to the r-process: the presence of a main r-process between the second and third peaks which is consistent among halo stars. We explore fission cycling and steady-beta flow as the driving mechanisms behind this feature. The presence of fission cycling during the r-process can account for nucleosynthesis yields between the second and third peaks, whereas the presence of steady-beta flow can account for consistent r-process patterns, robust under small variations in astrophysical conditions. We employ the neutrino-driven wind of the core-collapse supernova to examine fission cycling and steady-beta flow in the r-process. As the traditional neutrino-driven wind model does not produce the required very neutron-rich conditions for these mechanisms, we examine changes to the neutrino physics necessary for fission cycling to occur in the neutrino-driven wind environment, and we explore under what conditions steady-beta flow is obtained.
Temperature-Dependent Fission Barriers of Superheavy Nuclei
The dependence of fission barriers on the excitation energy of the compound nucleus impacts the survival probability of superheavy nuclei synthesized in heavy-ion fusion reactions. We study the temperature-dependent fission barriers by means of the self-consistent nuclear density functional theory. The equivalence of isothermal and isentropic descriptions is demonstrated. The effect of the particle gas is found to be negligible in the range of temperatures studied. Calculations have been carried out for $^{264}$Fm, $^{272}$Ds, $^{278}$112, $^{292}$114, and $^{312}$124. For nuclei around $^{278}$112 produced in "cold fusion" reactions, we predict a more rapid decrease of fission barriers with temperature as compared to the nuclei around $^{292}$114 synthesized in "hot fusion" experiments. This is explained in terms of the difference between the ground-state and fission-barrier temperatures. Our calculations are consistent with the long survival probabilities of the superheavy elements produced in Dubna with th...
Pei, J C; Sheikh-Javid, A; Kerman, A K
A body is presented for use in a thermal fission reactor comprising a sintered compressed mass of a substance of the group consisting of uranium, thorium, and oxides and carbides of uranium and thorium, enclosed in an envelope of a sintered, compacted, heat-conductive material of the group consisting of beryllium, zirconium, and oxides and carbides of beryllium and zirconium.
Blainey, A.
A method is presented for the separation of plutonium from solutions containing that element in a valence state not higher than 41 together with uranium ions and fission products. This separation is accomplished by contacting the solutions with diatomaceous earth which preferentially adsorbs the plutonium present. Also mentioned as effective for this adsorbtive separation are silica gel, filler's earth and alumina.
Seaborg, G.T.; Willard, J.E.
Perspective on the fusion-fission hybrid reactor
The hybrid reactor's role as a source of fuel for fission converter reactors is investigated. The role of the hybrid reactor in the energy economy, the interface between the hybrid reactor and the present fusion program, implications of the Carter Energy Plan, and the rationale for further hybrid reactor studies are discussed.
Bender, D.J.; Lee, J.D.; Moir, R.W.
Tracking in Antiproton Annihilation Experiments
A major ingredient of the planned new accelerator complex FAIR, to be constructed at the GSI, Darmstadt, Germany, is the availability of antiproton beams with high quality and intensity. Among the experiments which will make use of this opportunity is PANDA, a dedicated experiment to study antiproton annihilations on nucleons and nuclei. This article gives an overview on the foreseen techniques to perform charged particle tracking in the high rate environment of this experiment.
O. N. Hartmann
Infrared tag and track technique
A method of covertly tagging an object for later tracking includes providing a material capable of at least one of being applied to the object and being included in the object, which material includes deuterium; and performing at least one of applying the material to the object and including the material in the object in a manner in which in the appearance of the object is not changed, to the naked eye.
Partin, Judy K. (Idaho Falls, ID); Stone, Mark L. (Idaho Falls, ID); Slater, John (Albuquerque, NM); Davidson, James R. (Idaho Falls, ID)
Nuclear Design of the HOMER-15 Mars Surface Fission Reactor
The next generation of robotic missions to Mars will most likely require robust power sources in the range of 3 to 20 kWe. Fission systems are well suited to provide safe, reliable, and economic power within this range. The goal of this study is to design a compact, low-mass fission system that meets Mars surface power requirements, while maintaining a high level of safety and reliability at a relatively low cost. The Heat pipe Power System (HPS) is one possible approach for producing near-term, low-cost, space fission power. The goal of the HPS project is to devise an attractive space fission system that can be developed quickly and affordably. The primary ways of doing this are by using existing technology and by designing the system for inexpensive testing. If the system can be designed to allow highly prototypic testing with electrical heating, then an exhaustive test program can be carried out quickly and inexpensively, and thorough testing of the actual flight unit can be performed - which is a major benefit to reliability. Over the past 4 years, three small HPS proof-of-concept technology demonstrations have been conducted, and each has been highly successful. The Heat pipe-Operated Mars Exploration Reactor (HOMER) is a derivative of the HPS designed especially for producing power on the surface of Mars. The HOMER-15 is a 15-kWt reactor that couples with a 3-kWe Stirling engine power system. The reactor contains stainless-steel (SS)-clad uranium nitride (UN) fuel pins that are structurally and thermally bonded to SS/sodium heat pipes. Fission energy is conducted from the fuel pins to the heat pipes, which then carry the heat to the Stirling engine. This paper describes conceptual design and nuclear performance the HOMER-15 reactor. (author)
Poston, David I. [Nuclear Systems Design Group, Decision Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 (United States)
Short-lived fission product measurements from >0.1 MeV neutron-induced fission using boron carbide.
A boron carbide shield was designed, custom fabricated, and used to create a fast fission energy neutron spectrum. The fissionable isotopes 233, 235, 238U, 237Np, and 239Pu were separately placed inside of this shield and irradiated under pulsed conditions at the Washington State University 1 MW TRIGA reactor. A unique set of fission product gamma spectra were collected at short times (4 minutes to 1 week) post-fission. Gamma spectra were collected on single-crystal high purity germanium detectors and on Pacific Northwest National Laboratory's (PNNL's) Direct Simultaneous Measurement (DSM) system composed of HPGe detectors connected in coincidence. This work defines the experimental methods used to produce and collect the gamma data, and demonstrates the validity of the measurements. It is important to fully document this information so the data can be used with high confidence for the advancement of nuclear science and non-proliferation applications. The gamma spectra collected in these and other experiments will be made publicly available at https://spcollab.pnl.gov/sites/gammadata or via the link at http://rdnsgroup.pnl.gov. A revised version of this publication will be posted with the data to make the experimental details available to those using the data.
Finn, Erin C.; Metz, Lori A.; Greenwood, Lawrence R.; Pierson, Bruce D.; Friese, Judah I.; Kephart, Rosara F.; Kephart, Jeremy D.
Fission Product Data Measured at Los Alamos for Fission Spectrum and Thermal Neutrons on {sup 239}Pu, {sup 235}U, {sup 238}U
We describe measurements of fission product data at Los Alamos that are important for determining the number of fissions that have occurred when neutrons are incident on plutonium and uranium isotopes. The fission-spectrum measurements were made using a fission chamber designed by the National Institute for Standards and Technology (NIST) in the BIG TEN critical assembly, as part of the Inter-laboratory Liquid Metal Fast Breeder Reactor (LMFBR) Reaction Rate (ILRR) collaboration. The thermal measurements were made at Los Alamos' Omega West Reactor. A related set of measurements were made of fission-product ratios (so-called R-values) in neutron environments provided by a number of Los Alamos critical assemblies that range from having average energies causing fission of 400-600 keV (BIG TEN and the outer regions of the Flattop-25 assembly) to higher energies (1.4-1.9 MeV) in the Jezebel, and in the central regions of the Flattop-25 and Flattop-Pu, critical assemblies. From these data we determine ratios of fission product yields in different fuel and neutron environments (Q-values) and fission product yields in fission spectrum neutron environments for {sup 99}Mo, {sup 95}Zr, {sup 137}Cs, {sup 140}Ba, {sup 141,143}Ce, and {sup 147}Nd. Modest incident-energy dependence exists for the {sup 147}Nd fission product yield; this is discussed in the context of models for fission that include thermal and dynamical effects. The fission product data agree with measurements by Maeck and other authors using mass-spectrometry methods, and with the ILRR collaboration results that used gamma spectroscopy for quantifying fission products. We note that the measurements also contradict earlier 1950s historical Los Alamos estimates by {approx}5-7%, most likely owing to self-shielding corrections not made in the early thermal measurements. Our experimental results provide a confirmation of the England-Rider ENDF/B-VI evaluated fission-spectrum fission product yields that were carried over to the ENDF/B-VII.0 library, except for {sup 99}Mo where the present results are about 4%-relative higher for neutrons incident on {sup 239}Pu and {sup 235}U. Additionally, our results illustrate the importance of representing the incident energy dependence of fission product yields over the fast neutron energy range for high-accuracy work, for example the {sup 147}Nd from neutron reactions on plutonium. An upgrade to the ENDF library, for ENDF/B-VII.1, based on these and other data, is described in a companion paper to this work.
Selby, H.D., E-mail: firstname.lastname@example.com [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Mac Innes, M.R.; Barr, D.W.; Keksis, A.L.; Meade, R.A.; Burns, C.J.; Chadwick, M.B.; Wallstrom, T.C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
Spontaneous fission lifetimes from the minimization of self-consistent collective action
The spontaneous fission lifetime of 264Fm has been studied within nuclear density functional theory by minimizing the collective action integral for fission in a two-dimensional quadrupole collective space representing elongation and triaxiality. The collective potential and inertia tensor are obtained self-consistently using the Skyrme energy density functional and density-dependent pairing interaction. The resulting spontaneous fission lifetimes are compared with the static result obtained with the minimum-energy pathway. We show that fission pathways strongly depend on assumptions underlying collective inertia. With the non-perturbative mass parameters, the dynamic fission pathway becomes strongly triaxial and it approaches the static fission valley. On the other hand, when the standard perturbative cranking inertia tensor is used, axial symmetry is restored along the path to fission; an effect that is an artifact of the approximation used.
Jhilam Sadhukhan; K. Mazurek; A. Baran; J. Dobaczewski; W. Nazarewicz; J. A. Sheikh
Fission of heavy $?$ hypernuclei with the Skyrme-Hartree-Fock approach
Fission-related phenomena of heavy $\\Lambda$ hypernuclei are discussed with the constraint Skyrme-Hartree-Fock+BCS (SHF+BCS) method, in which a similar Skyrme-type interaction is employed also for the interaction between a $\\Lambda$ particle and a nucleon. Assuming that the $\\Lambda$ particle adiabatically follows the fission motion, we discuss the fission barrier height of $^{239}_{\\Lambda}$U. We find that the fission barrier height increases slightly when the $\\Lambda$ particle occupies the lowest level. In this case, the $\\Lambda$ particle is always attached to the heavier fission fragment. This indicates that one may produce heavy neutron-rich $\\Lambda$ hypernuclei through fission, whose weak decay is helpful for the nuclear transmutation of long-lived fission products. We also discuss cases where the $\\Lambda$ particle occupies a higher single-particle level.
F. Minato; S. Chiba; K. Hagino
Bulk and surface controlled diffusion of fission gas atoms
Fission gas retention and release impact nuclear fuel performance by, e.g., causing fuel swelling leading to mechanical interaction with the clad, increasing the plenum pressure and reducing the gap thermal conductivity. All of these processes are important to understand in order to optimize operating conditions of nuclear reactors and to simulate accident scenarios. Most fission gases have low solubility in the fuel matrix, which is especially pronounced for large fission gas atoms such as Xe and Kr, and as a result there is a significant driving force for segregation of gas atoms to extended defects such as grain boundaries or dislocations and subsequently for nucleation of gas bubbles at these sinks. Several empirical or semi-empirical models have been developed for fission gas release in nuclear fuels, e.g. [1-6]. One of the most commonly used models in fuel performance codes was published by Massih and Forsberg [3,4,6]. This model is similar to the early Booth model [1] in that it applies an equivalent sphere to separate bulk UO{sub 2} from grain boundaries represented by the sphere circumference. Compared to the Booth model, it also captures trapping at grain boundaries, fission gas resolution and it describes release from the boundary by applying timedependent boundary conditions to the circumference. In this work we focus on the step where fission gas atoms diffuse from the grain interior to the grain boundaries. The original Massih-Forsberg model describes this process by applying an effective diffusivity divided into three temperature regimes. In this report we present results from density functional theory calculations (DFT) that are relevant for the high (D{sub 3}) and intermediate (D{sub 2}) temperature diffusivities of fission gases. The results are validated by making a quantitative comparison to Turnbull's [8-10] and Matzke's data [12]. For the intrinsic or high temperature regime we report activation energies for both Xe and Kr diffusion in UO{sub 2{+-}x}, which compare favorably to available experiments. This is an extension of previous work [13]. In particular, it applies improved chemistry models for the UO{sub 2{+-}x} nonstoichiometry and its impact on the fission gas activation energies. The derivation of these models follows the approach that used in our recent study of uranium vacancy diffusion in UO{sub 2} [14]. Also, based on the calculated DFT data we analyze vacancy enhanced diffusion mechanisms in the intermediate temperature regime. In addition to vacancy enhanced diffusion we investigate species transport on the (111) UO{sub 2} surface. This is motivated by the formation of small voids partially filled with fission gas atoms (bubbles) in UO{sub 2} under irradiation, for which surface diffusion could be the rate-limiting transport step. Diffusion of such bubbles constitutes an alternative mechanism for mass transport in these materials.
Andersson, Anders D. [Los Alamos National Laboratory
Neutron Transport and Nuclear Burnup Analysis for the Laser Inertial Confinement Fusion-Fission Energy (LIFE) Engine
Kevin J. Kramer; Jeffery F. Latkowski; Ryan P. Abbott; John K. Boyd; Jeffrey J. Powers; Jeffrey E. Seifried
Tracking system for solar collectors
A tracking system is provided for pivotally mounted spaced-apart solar collectors. A pair of cables is connected to spaced-apart portions of each collector, and a driver displaces the cables, thereby causing the collectors to pivot about their mounting, so as to assume the desired orientation. The collectors may be of the cylindrical type as well as the flat-plate type. Rigid spar-like linkages may be substituted for the cables. Releasable attachments of the cables to the collectors is also described, as is a fine tuning mechanism for precisely aligning each individual collector.
Butler, B.
Butler, Barry L. (Golden, CO)
Two-axis tracking solar collector mechanism
This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion.
Johnson, Kenneth C. (201 W. California Ave., #401, Sunnyvale, CA 94086)
Johnson, Kenneth C. (201 W. California Ave. #705, Sunnyvale, CA 94086)
This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion. 16 figs.
Johnson, K.C.
Solid-state track recorder dosimetry device to measure absolute reaction rates and neutron fluence as a function of time
A solid state track recording type dosimeter is disclosed to measure the time dependence of the absolute fission rates of nuclides or neutron fluence over a period of time. In a primary species an inner recording drum is rotatably contained within an exterior housing drum that defines a series of collimating slit apertures overlying windows defined in the stationary drum through which radiation can enter. Film type solid state track recorders are positioned circumferentially about the surface of the internal recording drum to record such radiation or its secondary products during relative rotation of the two elements. In another species both the recording element and the aperture element assume the configuration of adjacent disks. Based on slit size of apertures and relative rotational velocity of the inner drum, radiation parameters within a test area may be measured as a function of time and spectra deduced therefrom.
Gold, Raymond (1393 George Washington Way, Suite No. 7, P.O. Box 944, Richland, WA 99352); Roberts, James H. (1393 George Washington Way, Suite No. 7, P.O. Box 944, Richland, WA 99352)
September 2013 Most Viewed Documents for Fission And Nuclear Technologies |
Fission And Nuclear Technologies Fission And Nuclear Technologies Estimation of gas leak rates through very small orifices and channels. [From sealed PuO/sub 2/ containers under accident conditions] Bomelburg, H.J. (1977) 133 Stress analysis and evaluation of a rectangular pressure vessel. [For equipment for sampling Hanford tank radwaste] Rezvani, M.A.; Ziada, H.H. (Westinghouse Hanford Co., Richland, WA (United States)); Shurrab, M.S. (Westinghouse Savannah River Co., Aiken, SC (United States)) (1992) 78 Graphite design handbook Ho, F.H. (1988) 76 Feed-pump hydraulic performance and design improvement, Phase I: research program design. Final report Brown, W.H.; Gopalakrishnan, S.; Fehlau, R.; Thompson, W.E.; Wilson, D.G. (1982) 69 Flow-induced vibration of circular cylindrical structures Chen, S.S. (1985)
Quasi-fission reactions as a probe of nuclear viscosity
Fission fragment mass and angular distributions were measured from the ^{64}Ni+^{197}Au reaction at 418 MeV and 383 MeV incident energy. A detailed data analysis was performed, using the one-body dissipation theory implemented in the code HICOL. The effect of the window and the wall friction on the experimental observables was investigated. Friction stronger than one-body was also considered. The mass and angular distributions were consistent with one-body dissipation. An evaporation code DIFHEAT coupled to HICOL was developed in order to predict reaction time scales required to describe available data on pre-scission neutron multiplicities. The multiplicity data were again consistent with one-body dissipation. The cross-sections for touch, capture and quasi-fission were also obtained.
J. Velkovska; C. R. Morton; R. L. McGrath; P. Chung; I. Dioszegi
Fission process of low excited nuclei with Langevin approach
Fragment mass distributions from the fission of U and Pu isotopes at low excitation energies are studied using a dynamical model based on the fluctuation-dissipation theorem formulated as Langevin equations. The present calculations reproduced the overall trend of the asymmetric mass distribution without parameter adjustment for the first time using the Langevin approach. The Langevin trajectories show a complicated time evolution on the potential surface, which causes the time delay of fission, showing that dynamical treatment is vital. It was found that the shell effect of the potential energy landscape has a dominant role in determining the mass distribution, although it is rather insensitive to the strength of dissipation. Nevertheless, it is essential to include the effect of dissipation, since it has a crucial role in giving "fluctuation" to Langevin trajectories as well as for explaining the multiplicities of pre-scission neutrons as the excitation energy increases. Therefore, the present approach can serve as a basis for more refined analysis.
Analysis of the lumped fission-product uncertainty in CRBR
An approximation made in most fast reactor analyses is to utilize a single lumped fission product (FP) cross-section set to represent the total effect of the approximately 800 possible fission product nuclides in a depleted reactor model. Recent investigations have analyzed several aspects of this one-lump approximation (burnup dependence, comparison with a two-lump model, etc.), but little has been done in addressing the quality, or uncertainty, in the basic cross-section data utilized in any such representation. Thus, the purpose of this study is to investigate the uncertainty in the FP reactivity effect due to the data uncertainties inherent in an ENDF/B-V composite FP representation specifically designed for application with the current CRBR heterogeneous core concept.
White, J.R.; Schenter, R.E.
Fission-Based Electric Propulsion for Interstellar Precursor Missions
This paper reviews the technology options for a fission-based electric propulsion system for interstellar precursor missions. To achieve a total {Delta}V of more than 100 km/s in less than a decade of thrusting with an electric propulsion system of 10,000s Isp requires a specific mass for the power system of less than 35 kg/kWe. Three possible configurations are described: (1) a UZrH-fueled,NaK-cooled reactor with a steam Rankine conversion system,(2) a UN-fueled gas-cooled reactor with a recuperated Brayton conversion system, and (3) a UN-fueled heat pipe-cooled reactor with a recuperated Brayton conversion system. All three of these systems have the potential to meet the specific mass requirements for interstellar precursor missions in the near term. Advanced versions of a fission-based electric propulsion system might travel as much as several light years in 200 years.
Advanced fission and fossil plant economics-implications for fusion
In order for fusion energy to be a viable option for electric power generation, it must either directly compete with future alternatives or serve as a reasonable backup if the alternatives become unacceptable. This paper discusses projected costs for the most likely competitors with fusion power for baseload electric capacity and what these costs imply for fusion economics. The competitors examined include advanced nuclear fission and advanced fossil-fired plants. The projected costs and their basis are discussed. The estimates for these technologies are compared with cost estimates for magnetic and inertial confinement fusion plants. The conclusion of the analysis is that fusion faces formidable economic competition. Although the cost level for fusion appears greater than that for fission or fossil, the costs are not so high as to preclude fusion`s potential competitiveness.
Delene, J.G.
Method of fission heat flux determination from experimental data
A method is provided for determining the fission heat flux of a prime specimen inserted into a specimen of a test reactor. A pair of thermocouple test specimens are positioned at the same level in the holder and a determination is made of various experimental data including the temperature of the thermocouple test specimens, the temperature of bulk water channels located in the test holder, the gamma scan count ratios for the thermocouple test specimens and the prime specimen, and the thicknesses of the outer clads, the fuel fillers, and the backclad of the thermocouple test specimen. Using this experimental data, the absolute value of the fission heat flux for the thermocouple test specimens and prime specimen can be calculated.
Paxton, Frank A. (Schenectady, NY)
April 2013 Most Viewed Documents for Fission And Nuclear Technologies |
April 2013 Most Viewed Documents for Fission And Nuclear Technologies April 2013 Most Viewed Documents for Fission And Nuclear Technologies Behavior of spent nuclear fuel in water pool storage Johnson, A.B. Jr. (null) 298 Estimation of gas leak rates through very small orifices and channels. [From sealed PuO/sub 2/ containers under accident conditions] Bomelburg, H.J. (null) 292 Graphite design handbook Ho, F.H. (1988) 216 System Definition and Analysis: Power Plant Design and Layout NONE (1996) 123 Flow-induced vibration of circular cylindrical structures Chen, S.S. (1985) 116 Stress analysis and evaluation of a rectangular pressure vessel. [For equipment for sampling Hanford tank radwaste] Rezvani, M.A.; Ziada, H.H. (Westinghouse Hanford Co., Richland, WA (United States)); Shurrab, M.S. (Westinghouse Savannah River Co., Aiken, SC (United
Compressive Object Tracking using Entangled Photons
We present a compressive sensing protocol that tracks a moving object by removing static components from a scene. The implementation is carried out on a ghost imaging scheme to minimize both the number of photons and the number of measurements required to form a quantum image of the tracked object. This procedure tracks an object at low light levels with fewer than 3% of the measurements required for a raster scan, permitting us to more effectively use the information content in each photon.
Omar S. Magańa-Loaiza; Gregory A. Howland; Mehul Malik; John C. Howell; Robert W. Boyd
Gas Turbine Hot Section Component Life Tracking
Damage tracking software—backed by comprehensive analysis techniques—provides a means for owners/operators to independently track and predict life consumption for critical gas turbine hot section components. Results can be compared with equipment supplier formulated intervals. This report updates the development status of damage tracking software for managing life-cycle costs by improving owner/operator understanding of component life and life consumption as a function of turbine ...
Building the RHIC tracking lattice model
In this note we outline the procedure to build a realistic lattice model for the RHIC beam-beam tracking simulation. We will install multipole field errors in the arc main dipoles, arc main quadrupols and interaction region magnets (DX, D0, and triplets) and introduce a residual closed orbit, tune ripples, and physical apertures in the tracking lattice model. Nonlinearities such as local IR multipoles, second order chromaticies and third order resonance driving terms are also corrected before tracking.
Luo, Y.; Fischer, W.; Tepikian, S.
Manhattan Project: The Discovery of Fission, 1938-1939
Lise Meitner and Otto Hahn, Kaiser-Wilhelm Institute, Berlin THE DISCOVERY OF FISSION Berlin, Germany (1938-1939) Events > Atomic Discoveries, 1890s-1939 A Miniature Solar System, 1890s-1919 Exploring the Atom, 1919-1932 Atomic Bombardment, 1932-1938 The Discovery of Fission, 1938-1939 Fission Comes to America, 1939 The English word "atom" derives from the Greek word "atomon" ("ατομον"), which means "that which cannot be divided." In 1938, the scientific community proved the Greek philosophers wrong by dividing the atom. Excerpt from the comic book "Adventures Inside the Atom." Click on this image or visit the "Library" to view the whole comic book. Fission, the basis of the atomic bomb, was discovered in Nazi Germany less than a year before the beginning of the Second World War. It was December 1938 when the radiochemists Otto Hahn (above, with Lise Meitner) and Fritz Strassmann, while bombarding elements with neutrons in their Berlin laboratory, made their unexpected discovery. They found that while the nuclei of most elements changed somewhat during neutron bombardment, uranium nuclei changed greatly and broke into two roughly equal pieces. They split and became not the new transuranic elements that some thought Enrico Fermi had discovered but radioactive barium isotopes (barium has the atomic number 56) and other fragments of the uranium itself. The substances Fermi had created in his experiments, that is, did more than resemble lighter elements -- they were lighter elements. The products of the Hahn-Strassmann experiment weighed less than that of the original uranium nucleus, and herein lay the primary significance of their findings. It folIowed from Albert Einstein's E=mc2 equation that the loss of mass resulting from the splitting process must have been converted into energy in the form of kinetic energy that could in turn be converted into heat.
In this paper a short review of the theoretical problems of the pionic radioactivity is presented. The essential experimental results obtained in the 18 years of existence of the nuclear pionic radioactivity are reviewed. Moreover, using the recent results on the spontaneous fission half lives TSF of the heavy nuclei with Z ? 100 new predictions on the pionic yields in the region of superheavy elements are established. 1
D. B. Ion; Reveica Ion-mihai; M. L. Ion; Adriana I. Sandru
Fuel elements for thermal-fission nuclear reactors are described. The fuel element is comprised of a core of alumina, a film of a metal of the class consisting of copper, silver, and nickel on the outer face of the core, and a coating of an oxide of a metal isotope of the class consisting of Un/sup 235/, U/ sup 233/, and Pu/sup 239/ on the metal f ilm.
Flint, O.
Data summary report for fission product release test VI-6
Test VI-6 was the sixth test in the VI series conducted in the vertical furnace. The fuel specimen was a 15.2-cm-long section of a fuel rod from the BR3 reactor in Belgium. The fuel had experienced a burnup of {approximately}42 MWd/kg, with inert gas release during irradiation of {approximately}2%. The fuel specimen was heated in an induction furnace at 2300 K for 60 min, initially in hydrogen, then in a steam atmosphere. The released fission products were collected in three sequentially operated collection trains designed to facilitate sampling and analysis. The fission product inventories in the fuel were measured directly by gamma-ray spectrometry, where possible, and were calculated by ORIGEN2. Integral releases were 75% for {sup 85}Kr, 67% for {sup 129}I, 64% for {sup 125}Sb, 80% for both {sup 134}Cs and {sup 137}Cs, 14% for {sup 154}Eu, 63% for Te, 32% for Ba, 13% for Mo, and 5.8% for Sr. Of the totals released from the fuel, 43% of the Cs, 32% of the Sb, and 98% of the Eu were deposited in the outlet end of the furnace. During the heatup in hydrogen, the Zircaloy cladding melted, ran down, and reacted with some of the UO{sub 2} and fission products, especially Te and Sb. The total mass released from the furnace to the collection system, including fission products, fuel, and structural materials, was 0.57 g, almost equally divided between thermal gradient tubes and filters. The release behaviors for the most volatile elements, Kr and Cs, were in good agreement with the ORNL Diffusion Model.
Osborne, M.F.; Lorenz, R.A.; Travis, J.R.; Webster, C.S.; Collins, J.L. [Oak Ridge National Lab., TN (United States)
Fission Product Benchmarking for Burnup Credit Applications: Progress Report
Progress toward developing a technical basis for a cost-effective burnup credit methodology for spent nuclear fuel with initial U-235 enrichment up to 5 percent is presented. Present regulatory practices provide as much burnup credit flexibility as can be currently expected. Further progress is achievable by incorporating the negative reactivity effects of a subset of neutron-absorbing fission product isotopes. Progress also depends on optimizing the procedure for establishing the burnup characteristics ...
Modeling of Molten Core Concrete Interactions and Fission Product Release
The study of molten core concrete interactions is important in estimating the possible consequences of a severe nuclear reactor accident. CORCON-Mod2 is a computer program that models the thermal, chemical, and physical phenomena associated with molten core concrete interactions. Models have been added to extend the modeling of these phenomena. An ideal solution chemical equilibrium methodology predicts the fission product vaporization release. Additional chemical species have been added, and the calcula...
Discrimination between roles of fissioning nucleus and asymmetry degree of freedom on the even-odd structure in fission-fragment yields
Based on a wide systematics of fission-fragment distributions measured in low-energy fission, the even-odd staggering in the fission-fragment element yields is investigated. The well-established evolution of the global even-odd effect with the fissioning system is found to be only a partial aspect of the even-odd structure. Indeed, it is shown that the global even-odd effect is varying systematically with the mean asymmetry of the fission-fragment distribution, and that the general increase of the even-odd staggering with asymmetry is depending on the fissioning system. Thus, the dependency of the even-odd effect with the fissioning system is accredited in part to the asymmetry evolution of the charge distribution, and not solely related to the dissipated energy as it has been done earlier. This interpretation is strongly supported by data measured in inverse kinematics, which cover the complete charge distribution and include precise yields at symmetry. The relevance of the order parameter to describe the even-odd effect in fission-fragment yields as a general property is explored.
M. Caamano; F. Rejmund; K. -H. Schmidt
Fission-suppressed fusion breeder on the thorium cycle and nonproliferation
Fusion reactors could be designed to breed fissile material while suppressing fissioning thereby enhancing safety. The produced fuel could be used to startup and makeup fuel for fission reactors. Each fusion reaction can produce typically 0.6 fissile atoms and release about 1.6 times the 14 MeV neutron's energy in the blanket in the fission-suppressed design. This production rate is 2660 kg/1000 MW of fusion power for a year. The revenues would be doubled from such a plant by selling fuel at a price of 60/g and electricity at $0.05/kWh for Q=P fusion /Pinput=4. Fusion reactors could be designed to destroy fission wastes by transmutation and fissioning but this is not a natural use of fusion whereas it is a designed use of fission reactors. Fusion could supply makeup fuel to fission reactors that were dedicated to fissioning wastes with some of their neutrons. The design for safety and heat removal and other items is already accomplished with fission reactors. Whereas fusion reactors have geometry that compromises safety with a complex and thin wall separating the fusion zone from the blanket zone where wastes could be destroyed. Nonproliferation can be enhanced by mixing 233U with 238U. Also nonproliferation is enhanced in typical fission-suppressed designs by generating up to 0.05 232U atoms for each 233U atom produced from thorium
Monitoring system for a liquid-cooled nuclear fission reactor
A monitoring system for detecting changes in the liquid levels in various regions of a water-cooled nuclear power reactor, viz., in the downcomer, in the core, in the inlet and outlet plenums, at the head, and elsewhere; and also for detecting changes in the density of the liquid in these regions. A plurality of gamma radiation detectors are used, arranged vertically along the outside of the reactor vessel, and collimator means for each detector limits the gamma-radiation it receives as emitting from only isolated regions of the vessel. Excess neutrons produced by the fission reaction will be captured by the water coolant, by the steel reactor walls, or by the fuel or control structures in the vessel. Neutron capture by steel generates gamma radiation having an energy level of the order of 5-12 MeV, whereas neutron capture by water provides an energy level of approximately 2.2 MeV, and neutron capture by the fission fuel or its cladding provides an energy level of 1 MeV or less. The intensity of neutron capture thus changes significantly at any water-metal interface. Comparative analysis of adjacent gamma detectors senses changes from the normal condition with liquid coolant present to advise of changes in the presence and/or density of the coolant at these specific regions. The gamma detectors can also sense fission-product gas accumulation at the reactor head to advise of a failure of fuel-pin cladding.
DeVolpi, Alexander (Bolingbrook, IL)
Method for motion tracking during tomographic scanning
Method for motion tracking during tomographic scanning Note: The technology described above is an early stage opportunity. Licensing rights to this intellectual ...
Measure, track, and benchmark | ENERGY STAR
tracking and benchmarking of energy across all operations are your most powerful energy waste reduction tools. Reducing energy waste requires that all forms of energy be...
Tracking Clean Energy Progress Energy Technology Perspectives...
Technology Perspectives 2012 excerpt as IEA input to the Clean Energy Ministerial Tracking Clean Energy Progress Energy Technology Perspectives 2012 Pathways to a Clean Energy...
Pollution Prevention Tracking and Reporting System
Welcome to the Department of Energy's Pollution Prevention Tracking and Reporting System (PPTRS). DOE uses this system to collect information about, and assess the performance of, the Department's...
TREC 2007 Legal Track: Main Task Glossary
TREC 2007 Legal Track: Main Task Glossary. Revision History. 2007 Oct 2: st: first draft. qrelsL07.normal. The qrelsL07.normal ...
Automated micro-tracking planar solar concentrators
Photonics) University of California, San Diego, 2011UNIVERSITY OF CALIFORNIA, SAN DIEGO Automated Micro-TrackingChair University of California, San Diego iii DEDICATION To
Hallas, Justin Matthew
A Comparison of Recent Reanalysis Datasets Using Objective Feature Tracking: Storm Tracks and Tropical Easterly Waves
Data from four recent reanalysis projects [ECMWF, NCEP–NCAR, NCEP–Department of Energy (DOE), NASA] have been diagnosed at the scale of synoptic weather systems using an objective feature tracking method. The tracking statistics indicate that, ...
K. I. Hodges; B. J. Hoskins; J. Boyle; C. Thorncroft
Integrating plan-view tracking and color-based person models for multiple people tracking
Tracking multiple people in a dynamic environment is important in many applications. Recent research in this area has focused either on geometric analysis or appearance models. In this paper we distinguish four types of tracking problems, and then describe an approach for combining geometric analysis and appearance-based tracking to "hold on to " people in three of these situations. 1.
Luca Iocchi; Robert C. Bolles
Tracking $f(R)$ cosmology
Metric $f(R)$ gravity theories are conformally equivalent to models of quintessence in which matter is coupled to dark energy. We derive a condition for stable tracker solution for metric $f(R)$ gravity in the Einstein frame. We find that tracker solutions with $-0.3610$, where $\\Gamma=\\frac{V_{\\varphi\\varphi}V}{V_{\\varphi}^{2}}$ is dimensionless function, $\\omega_{\\varphi}$ is the equation of state parameter of the scalar field and $\\tilde{R}$ refers to Jordan frame's curvature scalar. Also, we show that there exists $f(\\tilde{R})$ gravity models which have tracking behavior in the Einstein frame and so the curvature of space time is decreasing with time while they lead to the solutions in the Jordan frame that the curvature of space time can be increasing with time.
Mahmood Roshan; Fatimah Shojai
Position and orientation tracking system
A position and orientation tracking system presents a laser scanning appaus having two measurement pods, a control station, and a detector array. The measurement pods can be mounted in the dome of a radioactive waste storage silo. Each measurement pod includes dual orthogonal laser scanner subsystems. The first laser scanner subsystem is oriented to emit a first line laser in the pan direction. The second laser scanner is oriented to emit a second line laser in the tilt direction. Both emitted line lasers scan planes across the radioactive waste surface to encounter the detector array mounted on a target robotic vehicle. The angles of incidence of the planes with the detector array are recorded by the control station. Combining measurements describing each of the four planes provides data for a closed form solution of the algebraic transform describing the position and orientation of the target robotic vehicle.
Burks, Barry L. (Oak Ridge, TN); DePiero, Fred W. (Knoxville, TN); Armstrong, Gary A. (Oak Ridge, TN); Jansen, John F. (Knoxville, TN); Muller, Richard C. (Oak Ridge, TN); Gee, Timothy F. (Riceville, TN)
A position and orientation tracking system presents a laser scanning apparatus having two measurement pods, a control station, and a detector array. The measurement pods can be mounted in the dome of a radioactive waste storage silo. Each measurement pod includes dual orthogonal laser scanner subsystems. The first laser scanner subsystem is oriented to emit a first line laser in the pan direction. The second laser scanner is oriented to emit a second line laser in the tilt direction. Both emitted line lasers scan planes across the radioactive waste surface to encounter the detector array mounted on a target robotic vehicle. The angles of incidence of the planes with the detector array are recorded by the control station. Combining measurements describing each of the four planes provides data for a closed form solution of the algebraic transform describing the position and orientation of the target robotic vehicle. 14 figs.
Burks, B.L.; DePiero, F.W.; Armstrong, G.A.; Jansen, J.F.; Muller, R.C.; Gee, T.F.
This is a feasibility study of using a modern Graphics Processing Unit (GPU) to parallelize the accelerator particle tracking code. To demonstrate the massive parallelization features provided by GPU computing, a simplified TracyGPU program is developed for dynamic aperture calculation. Performances, issues, and challenges from introducing GPU are also discussed. General purpose Computation on Graphics Processing Units (GPGPU) bring massive parallel computing capabilities to numerical calculation. However, the unique architecture of GPU requires a comprehensive understanding of the hardware and programming model to be able to well optimize existing applications. In the field of accelerator physics, the dynamic aperture calculation of a storage ring, which is often the most time consuming part of the accelerator modeling and simulation, can benefit from GPU due to its embarrassingly parallel feature, which fits well with the GPU programming model. In this paper, we use the Tesla C2050 GPU which consists of 14 multi-processois (MP) with 32 cores on each MP, therefore a total of 448 cores, to host thousands ot threads dynamically. Thread is a logical execution unit of the program on GPU. In the GPU programming model, threads are grouped into a collection of blocks Within each block, multiple threads share the same code, and up to 48 KB of shared memory. Multiple thread blocks form a grid, which is executed as a GPU kernel. A simplified code that is a subset of Tracy++ [2] is developed to demonstrate the possibility of using GPU to speed up the dynamic aperture calculation by having each thread track a particle.
Nishimura, Hiroshi; Song, Kai; Muriki, Krishna; Sun, Changchun; James, Susan; Qin, Yong
Fission time-scale in experiments and in multiple initiation model
Rate of fission for highly-excited nuclei is affected by the viscose character of the systemmotion in deformation coordinates as was reported for very heavy nuclei with Z{sub C} > 90. The long time-scale of fission can be described in a model of 'fission by diffusion' that includes an assumption of the overdamped diabatic motion. The fission-to-spallation ratio at intermediate proton energy could be influenced by the viscosity, as well. Within a novel approach of the present work, the cross examination of the fission probability, time-scales, and pre-fission neutron multiplicities is resulted in the consistent interpretation of a whole set of the observables. Earlier, different aspects could be reproduced in partial simulations without careful coordination.
Karamian, S. A., E-mail: email@example.com [Joint Institute for Nuclear Research (Russian Federation)
An evaporation-based model of thermal neutron induced ternary fission of plutonium
Ternary fission probabilities for thermal neutron induced fission of plutonium are analyzed within the framework of an evaporation-based model where the complexity of time-varying potentials, associated with the neck collapse, are included in a simplistic fashion. If the nuclear temperature at scission and the fission-neck-collapse time are assumed to be ~1.2 MeV and ~10^-22 s, respectively, then calculated relative probabilities of ternary-fission light-charged-particle emission follow the trends seen in the experimental data. The ability of this model to reproduce ternary fission probabilities spanning seven orders of magnitude for a wide range of light-particle charges and masses implies that ternary fission is caused by the coupling of an evaporation-like process with the rapid re-arrangement of the nuclear fluid following scission.
J. P. Lestone
Fission barriers in neutron-proton isospin plane for heavy neutron-rich nuclei
We discuss the sensitivity of fission barrier for heavy neutron-rich nuclei to fission paths in the two dimensional neutron-proton quadrupole plane. To this end, we use the constrained Skyrme-Hartree-Fock + BCS method, and examine the difference of fission barriers obtained with three constraining operators, that is, the neutron, proton, and mass quadrupole operators. We investigate $^{220}$U, $^{236}$U, and $^{266}$U, %from proton-rich to neutron-rich uranium isotopes, that is relevant to r-process nucleosynthesis. We find that the fission barrier heights are almost the same among the three constraining operators even for neutron-rich nuclei, indicating that the usual way to calculate fission barriers with the mass quadrupole operator is well justified. We also discuss the difference between proton and neutron deformation parameters along the fission paths.
F. Minato; K. Hagino
A proposal is given of an approach to a fission-product trapping system which appears feasible on the basis of thermodynamic and other data available. Reactor and trapping conditions are outlined. The half-lives, fission yields, and volatility of the fission products of interest are described. To provide the most effective retention at elevated temperatures, two types of reagents are required: a highly electropositive metal that will not melt or appreciably vaporize and which will form stable non-volatile compounds with non-metallic or near non-metallic fission products; and a reagent to provide a highly electronegative element to form stable, non-volatile compounds with metallic fission products. Thermodynamic properties are included for compounds formed by reactions between the fission products and the trapping reagents. (B.O.G.)
Zumwalt, L.R.
Updated comparison of economics of fusion reactors with advanced fission reactors
The projected cost of electricity (COE) for fusion is compared with that from current and advanced nuclear fission and coal-fired plants. Fusion cost models were adjusted for consistency with advanced fission plants and the calculational methodology and cost factors follow guidelines recommended for cost comparisons of advanced fission reactors. The results show COEs of about 59--74 mills/kWh for the fusion designs considered. In comparison, COEs for future fission reactors are estimated to be in the 43--54 mills/kWh range with coal-fired plant COEs of about 53--69 mills/kWh ($2--3/GJ coal). The principal cost driver for the fusion plants relative to fission plants is the fusion island cost. Although the estimated COEs for fusion are greater than those for fission or coal, the costs are not so high as to preclude fusion's competitiveness as a safe and environmentally sound alternative.
Experimental Measurements of Short-Lived Fission Products from Uranium, Neptunium, Plutonium and Americium
Fission yields are especially well characterized for long-lived fission products. Modeling techniques incorporate numerous assumptions and can be used to deduce information about the distribution of short-lived fission products. This work is an attempt to gather experimental (model-independent) data on the short-lived fission products. Fissile isotopes of uranium, neptunium, plutonium and americium were irradiated under pulse conditions at the Washington State University 1 MW TRIGA reactor to achieve ~108 fissions. The samples were placed on a HPGe (high purity germanium) detector to begin counting in less than 3 minutes post irradiation. The samples were counted for various time intervals ranging from 5 minutes to 1 hour. The data was then analyzed to determine which radionuclides could be quantified and compared to the published fission yield data.
Metz, Lori A.; Payne, Rosara F.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Pierson, Bruce D.
Assessment of selected fission products in the Savannah River Site environment
Most of the radioactivity produced by the operation of a nuclear reactor results from the fission process, during which the nucleus of a fissionable atom (such as 235U) splits into two or more nuclei, which typically are radioactive. The Radionuclide Assessment Program (RAP) has reported on fission products cesium, strontium, iodine, and technetium. Many other radionuclides are produced by the fission process. Releases of several additional fission products that result in dose to the offsite population are discussed in this publication. They are 95Zr, 95Nb, 103Ru, 106Ru, 141Ce, and 144Ce. This document will discuss the production, release, migration, and dose to humans for each of these selected fission products.
Carlton, W.H.; Denham, M.
Information analysis of rail track for predictive maintenance
Track defects are deviation of actual from theoretical values of the tracks geometrical characteristics. Track defects are macroscopic and geometric in nature and are exclusively the consequence of train traffic. [5] Rail track maintenance in terms of ... Keywords: CURV, cant def, cross level, dipped left, gauge, predictive maintenance management, rail track geometry
R. B. Faiz; S. Singh
Primitive Analysis of the Ship Tracking Problem
Satellite images reveal tracks of enhanced solar reflectivity in low-level stratus clouds over the ocean that are known to be produced by the aerosols emitted from diesel-powered ships. The question arises: Can we track a ship from such images? A ...
J. R. Philip; J. W. Rottman
Target tracking with binary proximity sensors
We explore fundamental performance limits of tracking a target in a two-dimensional field of binary proximity sensors, and design algorithms that attain those limits while providing minimal descriptions of the estimated target trajectory. Using geometric ... Keywords: Sensor networks, binary sensing, distributed algorithms, fundamental limits, target tracking
Nisheeth Shrivastava; Raghuraman Mudumbai; Upamanyu Madhow; Subhash Suri
Tracking Vehicles in traffic Surveillance Video
We present a system for detecting and tracking vehicles in surveillance video. Our algorithm uses a simple motion model to determine salient regions in a sequence of video frames. Similar regions are associated between frames and clustered to yield coherent final tracks. The entire process is automatic and uses computation time that scales according to the size of the input video sequence.
Maire, M; Kamath, C
Optimal Adaptive Waveform Selection for Target Tracking
Optimal Adaptive Waveform Selection for Target Tracking Barbara La Scala Mohammad Rezaeian Bill algorithms. This paper describes an optimal adaptive waveform selection algorithm for target tracking. An adap- tive scheduling algorithm that selects the waveforms to be used in future epochs based on current
Rezaeian, Mohammad-Jafar
Adaptive DFT-based interferometer fringe tracking
An automatic interferometer fringe tracking system has been developed, implemented, and tested at the Infrared Optical Telescope Array (IOTA) Observatory at Mount Hopkins, Arizona. The system can minimize the optical path differences (OPDs) for all three ... Keywords: DFT, IOTA, fringe tracking, interferometry, real time
Edward Wilson; Ettore Pedretti; Jesse Bregman; Robert W. Mah; Wesley A. Traub
Mean field approach for tracking similar objects
In this paper, we consider the problem of tracking similar objects. We show how a mean field approach can be used to deal with interacting targets and we compare it with Markov Chain Monte Carlo (MCMC). Two mean field implementations are presented. The ... Keywords: Kalman filter, Mean field, Multi-target tracking, Particle filter
C. Medrano; J. E. Herrero; J. Martínez; C. Orrite
Assessment of fission product yields data needs in nuclear reactor applications
Studies on the build-up of fission products in fast reactors have been performed, with particular emphasis on the effects related to the physics of the nuclear fission process. Fission product yields, which are required for burn-up calculations, depend on the proton and neutron number of the target nucleus as well as on the incident neutron energy. Evaluated nuclear data on fission product yields are available for all relevant target nuclides in reactor applications. However, the description of their energy dependence in evaluated data is still rather rudimentary, which is due to the lack of experimental fast fission data and reliable physical models. Additionally, physics studies of evaluated JEFF-3.1.1 fission yields data have shown potential improvements, especially for various fast fission data sets of this evaluation. In recent years, important progress in the understanding of the fission process has been made, and advanced model codes are currently being developed. This paper deals with the semi-empirical approach to the description of the fission process, which is used in the GEF code being developed by K.-H. Schmidt and B. Jurado on behalf of the OECD Nuclear Energy Agency, and with results from the corresponding author's diploma thesis. An extended version of the GEF code, supporting the calculation of spectrum weighted fission product yields, has been developed. It has been applied to the calculation of fission product yields in the fission rate spectra of a MOX fuelled sodium-cooled fast reactor. Important results are compared to JEFF-3.1.1 data and discussed in this paper. (authors)
Kern, K.; Becker, M.; Broeders, C. [Institut fuer Neutronenphysik und Reaktortechnik, KIT Campus Nord, Hermann-von-Helmholtz-Platz 1, 76344 Leopoldshafen (Germany)
Neutron-flux profile monitor for use in a fission reactor
A neutron flux monitor is provided which consists of a plurality of fission counters arranged as spaced-apart point detectors along a delay line. As a fission event occurs in any one of the counters, two delayed current pulses are generated at the output of the delay line. The time separation of the pulses identifies the counter in which the particular fission event occurred. Neutron flux profiles of reactor cores can be more accurately measured as a result.
Kopp, M.K.; Valentine, K.H.
Nuclear fission barriers, mass parameters and spontaneous fission half lives of fermium isotopes calculated in a framework of the Skyrme Hartree-Fock-Bogoliubov model with the SkM* force are discussed. Zero-point energy corrections in the ground state are determined for each nucleus using the Gaussian overlap approximation of the generator coordinate method and in the cranking formalism. Results of spontaneous fission half lives are compared to experimental data.
Baran, A. [Maria Curie-Sklodowska University; Staszczak, Andrzej [ORNL; Nazarewicz, A. [Oak Ridge National Laboratory (ORNL)
Bismuth phosphate carrier precipitation processes are described for the separation of plutonium from fission products wherein in at least one step bismuth phosphate is precipitated in the presence of hexavalent plutonium thereby carrying a portion of the fission products from soluble plu tonium values. In this step, a cerium phosphate precipitate is formed in conjunction with the bismuth phosphate precipitate, thereby increasing the amount of fission products removed from solution.
Faris, B.F.; Olson, C.M.
Multi-Stage Multiple-Hypothesis Tracking
While multiple hypothesis tracking (MHT) is widely acknowledged as an effective methodology for multi-target surveillance, there is a challenge to manage effectively a potentially large number of track hypotheses. Advanced single-stage track-while-fuse does not always offer the best processing scheme. We study two instances where multi-stage MHT processing is beneficial–dense target scenarios and complementary-sensor surveillance–and propose two processing schemes for these challenges: track-break-fuse and trackbefore-fuse, respectively. We provide simulation results demonstrating the advantages of these schemes over track-while-fuse. Moregenerally, we argue that multi-stage MHT offers a powerful and flexible paradigm to circumvent limitations in conventional MHT processing.
Stefano Coraluppi; Craig Carthel
Phase-Field Simulation of Void and Fission-Gas Bubble Evolution in ...
Symposium, Mechanical Performance for Current and Next-Generation Nuclear Reactors. Presentation Title, Phase-Field Simulation of Void and Fission-Gas ...
Multi-Scale Modeling of Fission Gas Evolution in UO2
Fission gases in uranium dioxide (UO2) nuclear fuels, of which Xe is one of the most prominent, influence fuel performance during reactor operation and have ...
The event-by-event fission model FREYA is extended to spontaneous fission of actinides and a variety of neutron observables are studied for spontaneous fission and fission induced by thermal neutrons with a view towards possible applications for SNM detection. We have shown that event-by-event models of fission, such as FREYA, provide a powerful tool for studying fission neutron correlations. Our results demonstrate that these correlations are significant and exhibit a dependence on the fissioning nucleus. Since our method is phenomenological in nature, good input data are especially important. Some of the measurements employed in FREYA are rather old and statistics limited. It would be useful to repeat some of these studies with modern detector techniques. In addition, most experiments made to date have not made simultaneous measurements of the fission products and the prompt observables, such as neutron and photons. Such data, while obviously more challenging to obtain, would be valuable for achieving a more complete understanding of the fission process.
UO 2 fission gas release rates from atomistic calculations of intrinsic ...
Based on DFT and empirical potential calculations, the diffusivity of fission gas atoms (Xe) in UO2 nuclear fuel has been calculated for a range of ...
Kinetic Monte Carlo Study of Fission Gas and Grain Growth in ...
We have considered the effect of fission gas bubbles (primarily due to xenon and krypton) on the swelling of the nuclear fuel. Using an analytical model we have ...
FREYA-a new Monte Carlo code for improved modeling of fission chains
A new simulation capability for modeling of individual fission events and chains and the transport of fission products in materials is presented. FREYA ( Fission Yield Event Yield Algorithm ) is a Monte Carlo code for generating fission events providing correlated kinematic information for prompt neutrons, gammas, and fragments. As a standalone code, FREYA calculates quantities such as multiplicity-energy, angular, and gamma-neutron energy sharing correlations. To study materials with multiplication, shielding effects, and detectors, we have integrated FREYA into the general purpose Monte Carlo code MCNP. This new tool will allow more accurate modeling of detector responses including correlations and the development of SNM detectors with increased sensitivity.
Hagmann, C A; Randrup, J; Vogt, R L
Irradiation Effects on Fission Product Behavior in PyC and SiC
Abstract Scope, Understanding the mechanism and quantifying the rate by which fission products diffuse through CVD ?-silicon carbide (SiC) is crucial to the ...
Inverse beta decay reaction in $^{232}$Th and $^{233}$U fission antineutrino flux
Energy spectra of antineutrinos coming from $^{232}$Th and $^{233}$U neutron-induced fission are calculated, relevant inverse beta decay $\\bar{{\
G. Domogatski; V. Kopeikin; L. Mikaelyan; V. Sinev
Five-Dimensional Fission-Barrier Calulations from Se-70 to Cf-252
We present fission-barrier-height calculations for nuclei throught the Periodic Table based on a realistic macroscopic-microscopic model. Compared to other calculations: (1) we use a deformation space of sufficiently high dimension, sampled densely enough to describe the relevant topography of the fission potential, (2) we unambiguously find the physically relevant saddle points in this space, and (3) we formulate our model so that we obtain continuity of the potential energy at the division point between a single system and separated fission fragments or colliding nuclei, allowing us to (4) describe both fission-barrier heights and ground-state masses throughout the Periodic Table.
Peter Moller; Arnold J. Sierk; Akira Iwamoto
/sup 3/He-induced fission of nuclei 159
The fission of nuclei with 159fission theory, including precompound nucleon emission, indicates fission barriers which decrease only slightly relative to the liquid-drop model values with decreasing Z, approaching about 90% of the liquid-drop model barrier for Aroughly-equal160. These results are in contrast with measurements at higher angular momenta which indicate much lower fission barriers (60 to 70 % of the liquid-drop model) for this mass region. The angular correlations indicate complete, or slightly greater than complete momentum transfer to the compound system. This is in opposition to that observed using heavier projectiles where incomplete momentum transfer is probable.
Becchetti, F.D.; Hicks, K.H.; Fields, C.A.; Peterson, R.J.; Raymond, R.S.; Ristinen, R.A.; Ullmann, J.L.; Zaidins, C.S.
Singlet Fission Holds Two-for-One Potential in Solar Cells (Fact...
confirmed the first molecular compound specifically designed to exhibit multiple- exciton generation through singlet fission-in effect, producing two electrons for every one photon...
Cost of Processing Fuel from a Molten Salt, Fusion/Fission, Hybrid Reactor Blanket
Blanket and Process Engineering / Proceedings of the Second National Topical Meeting on Tritium Technology in Fission, Fusion and Isotopic Applications (Dayton, Ohio, April 30 to May 2, 1985)
J. S. Watson; W. R. Grimes; D. E. Brashears
Tracking formulas and strategies for a receiver oriented dual-axis tracking toroidal heliostat
A 4 m x 4 m toroidal heliostat with receiver oriented dual-axis tracking, also called spinning-elevation tracking, was developed as an auxiliary heat source for a hydrogen production system. A series of spinning-elevation tracking formulas have been derived for this heliostat. This included basic tracking formulas, a formula for the elevation angle for heliostat with a mirror-pivot offset, and a more general formula for the biased elevation angle. This paper presents the new tracking formulas in detail and analyzes the accuracy of applying a simplifying approximation. The numerical results show these receiver oriented dual-axis tracking formula approximations are accurate to within 2.5 x 10{sup -6} m in image plane. Some practical tracking strategies are discussed briefly. Solar images from the toroidal heliostat at selected times are also presented. (author)
Guo, Minghuan; Wang, Zhifeng; Liang, Wenfeng; Zhang, Xiliang; Zang, Chuncheng [Key Laboratory of Solar Thermal Energy and Photovoltaic System of Chinese Academy of Sciences, Institute of Electrical Engineering, Beijing 100190 (China); Lu, Zhenwu; Wei, Xiudong [Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences (CAS), Jilin 130033 (China)
The Hanford Federal Facility Agreement and Consent Order, known as the ''Tri-Party Agreement'' (TPA), is a legally binding agreement among the US Department of Energy (DOE), The Washington State Department of Ecology, and the US Environmental Protection Agency (EPA) for cleaning up the Hanford Site. Established in the 1940s to produce material for nuclear weapons as part of the Manhattan Project, Hanford is often referred to as the world's large environmental cleanup project. The Site covers more than 580 square miles in a relatively remote region of southeastern Washington state in the US. The production of nuclear materials at Hanford has left a legacy of tremendous proportions in terms of hazardous and radioactive waste. From a waste-management point of view, the task is enormous: 1700 waste sites; 450 billion gallons of liquid waste; 70 billion gallons of contaminated groundwater; 53 million gallons of tank waste; 9 reactors; 5 million cubic yards of contaminated soil; 22 thousand drums of mixed waste; 2.3 tons of spent nuclear fuel; and 17.8 metric tons of plutonium-bearing material and this is just a partial listing. The agreement requires that DOE provide the results of analytical laboratory and non-laboratory tests/readings to the lead regulatory agency to help guide then in making decisions. The agreement also calls for each signatory to preserve--for at least ten years after the Agreement has ended--all of the records in it, or its contractors, possession related to sampling, analysis, investigations, and monitoring conducted. The Action Plan that supports the TPA requires that Ecology and EPA have access to all data that is relevant to work performed, or to be performed, under the Agreement. Further, the Action Plan specifies two additional requirements: (1) that EPA, Ecology and their respective contractor staffs have access to all the information electronically, and (2) that the databases are accessible to, and used by, all personnel doing TPA-related work. The Hanford Environmental Databases document and track the progress of Site cleanup--Hanford Environmental Information System (HEIS), Hanford Well Information Data System (HWIS), the Waste Information Data System (WIDS), and the Hanford Geographic Information System (HGIS). HEIS contains the date, time, location, and results from samples taken during activities such as field investigations and groundwater monitoring. HWIS contains the details of the wells and boreholes on the Site. WIDS tracks the waste sites--from discovery through cleanup. Each of the databases is supported by several applications for entering or retrieving information. HGIS keeps track of the locations for waste (WIDS) sites, wells and boreholes, and other sampling site locations. Of the applications used to extract data from the Environmental Databases, the Hanford Map Portal (QMAP) is the newest, and perhaps the most efficient. QMAP combines the HGIS spatial information with the information from the other databases so that users may browse to, or query, the waste site or well of interest. A query of a waste site or well engages QMAP to find the object and then the user may access the appropriate database. This paper describes the Environmental Databases and their maintenance, as well as the applications used to access them. Collectively, these databases are a critical element in formally documenting the work and associated decisions made during the cleanup of Hanford.
Bi-iterative least-square method for subspace tracking
schemes for ef?cient subspace tracking," IEEE Trans. SignalLinebarger, "Subspace tracking". [11] E. M. Dowling, L. P.angle and frequency tracking," IEEE Trans. Signal Process. ,
Ouyang, S; Hua, Y
ATLAS Tracking Event Data Model -- 12.0.0
offline/? cvsroot=atlas : Tracking/TrkEvent/TrkSegment [14]offline/? cvsroot=atlas : Tracking/TrkEvent/TrkSpacePoint [offline/? cvsroot=atlas : Tracking/TrkDetDescr/TrkSurface
Akesson, F.; ATLAS
Delayed neutron measurements from fast fission of actinide waste isotopes
A study was performed to determine the delayed neutron emission properties from fast fission of several actinide waste isotopes. The specific isotopes evaluated were U-235, Np-237, and Am-243. A calculational technique based on the microscopic method was used to predict initial guesses for the delayed neutron parameters (group decay constants and yields). Based on these calculations, an alternate "seven-group" structure, in contrast to the traditional "six-group" structure used previously, was suggested which would yield a superior fit to the measured data. A series of measurements were performed to test the hypothesis suggested by this alternate group structure. Using a set of highly purified actinide samples (provided by Oak Ridge National Laboratory), the delayed neutron emission decay constants and yields for six groups of the "seven-group" structure were measured for U-235, Np-237, and Am-243. These experiments were performed using the Texas A&M University Nuclear Science Center Reactor, a quick pneumatic transfer system, an integrated computer control and counting system, and a specially designed in-core irradiation device. The values for the total delayed neutron yield (per 100 fissions) from fast-neutron induced fission of U-235, Np237, and Am-243 were determined to be 1.67 ?0.08, 1.14 ?0.07, 0.86 ?0.05, respectively. The newly measured values were compared with other values recommended by Keepin et al., Waldo et al., Saleh et al., and Brady and England. Good agreement was found in all cases. The "seven-group" structure was shown to yield a superior fit to the measured data, as well as, provide a more direct correlation between delayed neutron groups and their associated delayed neutron precursors.
Charlton, William S.
Evidence-Based Medicine, the Essential Role of Systematic Reviews,
article is then read. Second, if the full text article proves to meet the inclusion criteria, the evidence the abstract and possibly the full text. Inclusion/exclusion decisions are tracked in reference manager information present within summaries or full-text of individual articles (Demner- Fushman, Few, Hauser
Meng, Weiyi
Non-Markovian large amplitude motion and nuclear fission
The general problem of dissipation in macroscopic large-amplitude collective motion and its relation to energy diffusion of intrinsic degrees of freedom of a nucleus is studied. By applying the cranking approach to the nuclear many body system, a set of coupled dynamical equations for the collective classical variables and the quantum mechanical occupancies of the intrinsic nuclear states is derived. Different dynamical regimes of the intrinsic nuclear motion and its consequences on time properties of collective dissipation are discussed. The approach is applied to the descant of the nucleus from the fission barrier.
V. M. Kolomietz; S. V. Radionov
Fission involves a new state of nuclear matter
The rearrangement step of nuclear fission occurs within 0.17 yoctosecond, in a new state of nuclear matter characterized by the formation of closed shells of nucleons. The determination of its lifetime is now based on the prompt neutron emission law. The width of isotopic distributions measures the uncertainty in the neutron number of the fragments. Magic mass numbers, 82 and 126, play a major role in the mass distributions. Arguments are presented in favour of an all-neutron state. The boson field responsible for the new collective interaction has to be searched for.
C. Ythier; S. Hachem; G. Mouze
An outline is presented of the potential applications and quantity requiremerts of fission products for the period 1964 to 1968. These applications include military, governmert, and civilian heat sources; irradiation processing; and food irradiation. The potential requirements for 1964 to 1968 are 273 MC / sup 90/Sr and 351 MC /sup 137/Cs. An evaluation is made of the applications of heat-producing isotopes in Coast Guard navigational buoys, lights, and beacons; undersea electronic systems; and weather stations. Costs were determined for conventional methods of power generation and compared to radioisotope power generation. Fuel requiremerts and break-even fuel costs for isotopic power are tabulated. (D.L.C.)
Radiolysis Concerns for Water Shielding in Fission Surface Power Applications
This paper presents an overview of radiolysis concerns with regard to water shields for fission surface power. A review of the radiolysis process is presented and key parameters and trends are identified. From this understanding of the radiolytic decomposition of water, shield pressurization and corrosion are identified as the primary concerns. Existing experimental and modeling data addressing concerns are summarized. It was found that radiolysis of pure water in a closed volume results in minimal, if any net decomposition, and therefore reduces the potential for shield pressurization and corrosion.
Schoenfeld, Michael P. [NASA Marshall Space Flight Center, ER24, MSFC, AL 35812 (United States); Anghaie, Samim [Innovative Space Power and Propulsion Institute, 800 SW Archer Rd. Bldg.554, P.O. Box 116502, University of Florida, Gainesville, FL 32611-6502 (United States)
Fission: theory and beyond (a study of collective dynamics)
From correlation on nuclei conference; Lake Balaton, Hungary (3 Sep 1973). The topic of the dynamics of the fission process has two subdivisions, the determination of the inertial mass parameters and the study of deviations from adiabaticity, excitation of singleparticle levels, viscosity, etc. The problems of dynamics are studied, with attention directed to the role of nuclear correlations. Two alternate forms for the mass parameter are presented. The first is variational, but it requires the evaluation of matrix elements involving the Hamiltonian. The other does not involve the Hamiltonian, but rather it utilizes the physical content of the wave function. (1 figures) (RWR)
Wilets, L.; Haff, P.K.
Cryogenic method for measuring nuclides and fission gases
A cryogenic method is provided for determining airborne gases and particulates from which gamma rays are emitted. A special dewar counting vessel is filled with the contents of the sampling flask which is immersed in liquid nitrogen. A vertically placed sodium-iodide or germanium-lithium gamma-ray detector is used. The device and method are of particular use in measuring and identifying the radioactive noble gases including emissions from coal-fired power plants, as well as fission gases released or escaping from nuclear power plants.
Perdue, P.T.; Haywood, F.F.
NEET Micro-Pocket Fission Detector -- FY 2012 Status Report
A research program has been initiated by the NEET program for developing and testing compact miniature fission chambers capable of simultaneously measuring thermal neutron flux, fast neutron flux and temperature within a single package. When implemented, these sensors will significantly advance flux detection capabilities for irradiation tests in US Materials Test Reactors (MTRs).Ultimately, evaluations may lead to a more compact, more accurate, and longer lifetime flux sensor for critical mock-ups, high performance reactors and commercial nuclear power plants. Deployment of Micro-Pocket Fission Detectors (MPFDs) in US DOE-NE program irradiation tests will address several challenges: Current fission chamber technologies do not offer the ability to measure fast flux, thermal flux and temperature within a single compact probe, MPFDs offer this option. MPFD construction is very different then current fission chamber construction; the use of high temperature materials allow MPFDs to be specifically tailored to survive harsh conditions in typical high performance MTR irradiation tests. New high-fidelity reactor physics codes will need a small, accurate, multipurpose in-core sensor to validate the codes without perturbing the validation experiment; MPFDs fill this requirement. MPFDs can be built with variable sensitivities to survive the lifetime of an experiment or fuel assembly in some MTRs; allowing for more efficient and cost effective power monitoring. The small size of the MPFDs allows multiple sensors to be simultaneously deployed; obtaining data required to visualize the reactor flux and temperature profiles. This report summarizes the research progress for year 1 of this 3 year project. An updated design of the MPFD has been developed, materials and tools to support the new design have been procured, construction methods to support the new design have been initiated at INL's HTTL and KSU's SMART Laboratory, plating methods are being updated at KSU, new detector electronics have been designed, built and tested at KSU. In addition, a project meeting was held at KSU and a detector evaluation plan has been initiated between INL and KSU. Once NEET program evaluations are completed, the final MPFD will be deployed in MTR irradiations, enabling DOE-NE programs evaluating the performance of candidate new fuels and materials to better characterize irradiation test conditions.
Troy Unruh; Joy Rempe; Douglas McGregor; Philip Ugorowski; Michael Reichenberger
shrinkage cracking, (b) fission product attack of SiC, and (in a pebble and pebbles in a bed in a hybrid LIFE fissionDiffusion coefficients of fission product species in UO 2 as
ORO Verification of Employment Tracking System(VETS) PIA, Oak...
Verification of Employment Tracking System(VETS) PIA, Oak ridge Operations Office ORO Verification of Employment Tracking System(VETS) PIA, Oak ridge Operations Office ORO...
Enhancements to System for Tracking Radioactive Waste Shipments...
Enhancements to System for Tracking Radioactive Waste Shipments Benefit Multiple Users Enhancements to System for Tracking Radioactive Waste Shipments Benefit Multiple Users...
ORO Office Safeguards and Security Clearance Tracking System...
Office Safeguards and Security Clearance Tracking System and Visitor Control System PIA, Oak Ridge Operations Office ORO Office Safeguards and Security Clearance Tracking System...
Sandia Sled Track PNOV Press Release | Department of Energy
Sandia Sled Track PNOV Press Release Sandia Sled Track PNOV Press Release On October 18, 2010, the National Nuclear Security Administration (NNSA) issued a Preliminary Notice of...
Tracking Rotational Diffusion of Colloidal Clusters
We describe a novel method of tracking the rotational motion of clusters of colloidal particles. Our method utilizes rigid body transfor- mations to determine the rotations of a cluster and extends conventional proven particle tracking techniques in a simple way, thus facilitating the study of rotational dynamics in systems containing or composed of colloidal clusters. We test our method by measuring dynamical properties of simulated Brownian clusters under conditions relevant to microscopy experiments. We then use the technique to track and describe the motions of a real colloidal cluster imaged with confocal microscopy.
Gary L. Hunter; Kazem V. Edmond; Mark T. Elsesser; Eric R. Weeks
Improvements for group delay fringe tracking
Group delay fringe tracking using spectrally-dispersed fringes is suitable for stabilising the optical path difference in ground-based astronomical optical interferometers in low light situations. We discuss the performance of group delay tracking algorithms when the effects of atmospheric dispersion, high-frequency atmospheric temporal phase variations, non-ideal path modulation, non-ideal spectral sampling, and the detection artifacts introduced by electron-multiplying CCDs (EMCCDs) are taken into account, and we present ways in which the tracking capability can be optimised in the presence of these effects.
A. G. Basden; D. F. Buscher
Dynamic aperture (DA) optimization with direct particle tracking is a straight forward approach when the computing power is permitted. It can have various realistic errors included and is more close than theoretical estimations. In this approach, a fast and parallel tracking code could be very helpful. In this presentation, we describe an implementation of storage ring particle tracking code TESLA for beam dynamics optimization. It supports MPI based parallel computing and is robust as DA calculation engine. This code has been used in the NSLS-II dynamics optimizations and obtained promising performance.
Yang, L.
ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data
The ENDF/B-VII.1 library is our latest recommended evaluated nuclear data file for use in nuclear science and technology applications, and incorporates advances made in the five years since the release of ENDF/B-VII.0. These advances focus on neutron cross sections, covariances, fission product yields and decay data, and represent work by the US Cross Section Evaluation Working Group (CSEWG) in nuclear data evaluation that utilizes developments in nuclear theory, modeling, simulation, and experiment. The principal advances in the new library are: (1) An increase in the breadth of neutron reaction cross section coverage, extending from 393 nuclides to 423 nuclides; (2) Covariance uncertainty data for 190 of the most important nuclides, as documented in companion papers in this edition; (3) R-matrix analyses of neutron reactions on light nuclei, including isotopes of He; Li, and Be; (4) Resonance parameter analyses at lower energies and statistical high energy reactions for isotopes of Cl; K; Ti, V, Mn, Cr, Ni, Zr and W; (5) Modifications to thermal neutron reactions on fission products (isotopes of Mo, Tc, Rh, Ag, Cs, Nd, Sm, Eu) and neutron absorber materials (Cd, Gd); (6) Improved minor actinide evaluations for isotopes of U, Np, Pu, and Am (we are not making changes to the major actinides (235,238)U and (239)Pu at this point, except for delayed neutron data and covariances, and instead we intend to update them after a further period of research in experiment and theory), and our adoption of JENDL-4.0 evaluations for isotopes of Cm, Bk, Cf, Es; Fm; and some other minor actinides; (7) Fission energy release evaluations; (8) Fission product yield advances for fission-spectrum neutrons and 14 MeV neutrons incident on (239)Pu; and (9) A new decay data sublibrary. Integral validation testing of the ENDF/B-VII.1 library is provided for a variety of quantities: For nuclear criticality, the VII.1 library maintains the generally-good performance seen for VII.0 for a wide range of MCNP simulations of criticality benchmarks, with improved performance coming from new structural material evaluations, especially for Ti, Mn, Cr, Zr and W. For Be we see some improvements although the fast assembly data appear to be mutually inconsistent. Actinide cross section updates are also assessed through comparisons of fission and capture reaction rate measurements in critical assemblies and fast reactors, and improvements are evident. Maxwellian-averaged capture cross sections at 30 keV are also provided for astrophysics applications. We describe the cross section evaluations that have been updated for ENDF/B-VII.1 and the measured data and calculations that motivated the changes, and therefore this paper augments the ENDF/B-VII.0 publication [H.
Chadwick, M. B. [Los Alamos National Laboratory (LANL); Herman, Micheal W [Brookhaven National Laboratory (BNL); Oblozinsky, Pavel [Brookhaven National Laboratory (BNL); Dunn, Michael E [ORNL; Danon, Y. [Rensselaer Polytechnic Institute (RPI); Kahler, A. [Los Alamos National Laboratory (LANL); Smith, Donald L. [Argonne National Laboratory (ANL); Pritychenko, B [Brookhaven National Laboratory (BNL); Arbanas, Goran [ORNL; Arcilla, r [Brookhaven National Laboratory (BNL); Brewer, R [Los Alamos National Laboratory (LANL); Brown, D A [Brookhaven National Laboratory (BNL); Capote, R. [International Atomic Energy Agency (IAEA); Carlson, A. D. [National Institute of Standards and Technology (NIST); Cho, Y S [Korea Atomic Energy Research Institute; Derrien, Herve [ORNL; Guber, Klaus H [ORNL; Hale, G. M. [Los Alamos National Laboratory (LANL); Hoblit, S [Brookhaven National Laboratory (BNL); Holloway, Shannon T. [Los Alamos National Laboratory (LANL); Johnson, T D [Brookhaven National Laboratory (BNL); Kawano, T. [Los Alamos National Laboratory (LANL); Kiedrowski, B C [Los Alamos National Laboratory (LANL); Kim, H [Korea Atomic Energy Research Institute; Kunieda, S [Los Alamos National Laboratory (LANL); Larson, Nancy M [ORNL; Leal, Luiz C [ORNL; Lestone, J P [Los Alamos National Laboratory (LANL); Little, R C [Los Alamos National Laboratory (LANL); Mccutchan, E A [Brookhaven National Laboratory (BNL); Macfarlane, R E [Los Alamos National Laboratory (LANL); MacInnes, M [Los Alamos National Laboratory (LANL); Matton, C M [Lawrence Livermore National Laboratory (LLNL); Mcknight, R D [Argonne National Laboratory (ANL); Mughabghab, S F [Brookhaven National Laboratory (BNL); Nobre, G P [Brookhaven National Laboratory (BNL); Palmiotti, G [Idaho National Laboratory (INL); Palumbo, A [Brookhaven National Laboratory (BNL); Pigni, Marco T [ORNL; Pronyaev, V. G. [Institute of Physics and Power Engineering (IPPE), Obninsk, Russia; Sayer, Royce O [ORNL; Sonzogni, A A [Brookhaven National Laboratory (BNL); Summers, N C [Lawrence Livermore National Laboratory (LLNL); Talou, P [Los Alamos National Laboratory (LANL); Thompson, I J [Lawrence Livermore National Laboratory (LLNL); Trkov, A. [Jozef Stefan Institute, Slovenia; Vogt, R L [Lawrence Livermore National Laboratory (LLNL); Van der Marck, S S [Nucl Res & Consultancy Grp, Petten, Netherlands; Wallner, A [University of Vienna, Austria; White, M C [Los Alamos National Laboratory (LANL); Wiarda, Dorothea [ORNL; Young, P C [Los Alamos National Laboratory (LANL)
Pair breaking and Coulomb effects in cold fission from thermal neutron induced fission of U 233, U 235 and Pu 239
In this paper, the distribution of mass and kinetic energy in the cold region of the thermal neutron induced fission of U 233, U 235 and Pu 239, respectively, is interpreted in terms of nucleon pair-breaking and the Coulomb interaction energy between complementary fragments (Coulomb effect). In order to avoid the erosive consequences of neutron emission, one studies the cold fission regions, corresponding to total kinetic energy (TE) close to the maximum available energy of the reaction (Q). Contrary to expected, in cold fission is not observed high odd-even effect in mass number distribution. Nevertheless, the measured values are compatible with higher odd-even effects on proton or neutron number distribution, respectively. In addition, in cold fission, the minimal total excitation energy (X) is correlated with the Coulomb energy excess, which is defined as the difference between C (the electrostatic interaction energy between complementary fragments taken as spherical in scission configuration) and Q. These...
Montoya, Modesto
Simulating NMIS Imaging and Fission-Mapping Measurements
The Nuclear Materials Identification System (NMIS) detects and characterizes fissile and nonfissile materials using time correlations between a time-tagged source and one or more detectors. The first fieldable configuration of dedicated hardware and software was developed in the 1990s. In its original configuration, the measurement system consisted of a time-tagged source and two to four detectors. Measurements with this configuration were easily simulated using a single Monte Carlo run. The present measurement configuration is far more complex than the original. The source is now divided into multiple neutron cones; significantly more detectors are included; and the source, detectors, and object being interrogated can all be moved during the measurement to capture different views of the object. In addition to the hardware changes, the software can now reconstruct high-resolution tomographs of the 14 MeV neutron attenuation coefficients and fission sites inside the object. This work shows how a complex measurement of an object that consists of both fissile and nonfissile parts can be simulated by using multiple input decks and combining the resulting output into the desired format. The results of this simulation were then reconstructed using the imaging and fission-mapping software used with measurements. These reconstructions are consistent with the original model, thus validating the simulation method.
Grogan, Brandon R [ORNL; Mihalczo, John T [ORNL
The neutronics studies of fusion fission hybrid power reactor
In this paper, a series of neutronics analysis of hybrid power reactor is proposed. The ideas of loading different fuels in a modular-type fission blanket is analyzed, fitting different level of fusion developments, i.e., the current experimental power output, the level can be obtained in the coming future and the high-power fusion reactor like ITER. The energy multiplication of fission blankets and tritium breeding ratio are evaluated as the criterion of design. The analysis is implemented based on the D-type simplified model, aiming to find a feasible 1000MWe hybrid power reactor for 5 years' lifetime. Three patterns are analyzed: 1) for the low fusion power, the reprocessed fuel is chosen. The fuel with high plutonium content is loaded to achieve large energy multiplication. 2) For the middle fusion power, the spent fuel from PWRs can be used to realize about 30 times energy multiplication. 3) For the high fusion power, the natural uranium can be directly used and about 10 times energy multiplication can be achieved.
Zheng Youqi; Wu Hongchun; Zu Tiejun; Yang Chao; Cao Liangzhi [School of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049 (China)
Report on Fission Time Projection Chamber M3FT-12IN0210052
The Time Projection Chamber is a collaborative effort to implement an innovative approach and deliver unprecedented fission measurements to DOE programs. This 4?-detector system will provide unrivaled 3-D data about the fission process. Shown here is a half populated TPC (2?) at the LLNL TPC laboratory as it undergoes testing before being shipped to LANSCE for beam experiments.
James K. Jewell
this century with OTC) · Closing the nuclear fuel cycle requires augmenting with fast reactors the present nuclear fuel discharged from LWRs ii) Fast Breeder Reactors which transmute the non-fissionable U-238 (>99-Fission Hybrid (FFH) is a subcritical nuclear reactor with a fusion neutron source. · The motivation for the FFH
Quantum and Thermodynamic Properties of Spontaneous and Low-Energy Induced Fission of Nuclei
It is shown that A. Bohr's concept of transition fission states can be matched with the properties of Coriolis interaction if an axisymmetric fissile nucleus near the scission point remains cold despite a nonadiabatic character of nuclear collective deformation motion. The quantum and thermodynamic properties of various stages of binary and ternary fission after the descent of a fissile nucleus from the outer saddle point are studied within quantum-mechanical fission theory. It is shown that two-particle nucleon-nucleon correlations--in particular, superfluid correlations--play an important role in the formation of fission products and in the classification of fission transitions. The distributions of thermalized primary fission fragments with respect to spins and their projections onto the symmetry axis of the fissile nucleus and fission fragments are constructed, these distributions determining the properties of prompt neutrons and gamma rays emitted by these fragments. A new nonevaporation mechanism of third-particle production in ternary fission is proposed. This mechanism involves transitions of third particles from the cluster states of the fissile-nucleus neck to high-energy states under effects of the shake-off type that are due to the nonadiabatic character of nuclear collective deformation motion.
Kadmensky, S.G. [Voronezh State University, Universitetskaya pl. 1, Voronezh, 394693 (Russian Federation)
Measurement and Analysis of Fission Rates in a Spherical Mockup of Uranium and Polyethylene
Measurements of the reaction rate distribution were carried out using two kinds of Plate Micro Fission Chamber(PMFC). The first is a depleted uranium chamber and the second an enriched uranium chamber. The material in the depleted uranium chamber is strictly the same as the material in the uranium assembly. With the equation solution to conduct the isotope contribution correction, the fission rate of 238U and 235U were obtained from the fission rate of depleted uranium and enriched uranium. And then, the fission count of 238U and 235U in an individual uranium shell was obtained. In this work, MCNP5 and continuous energy cross sections ENDF/BV.0 were used for the analysis of fission rate distribution and fission count. The calculated results were compared with the experimental ones. The calculation of fission rate of DU and EU were found to agree with the measured ones within 10% except at the positions in polyethylene region and the two positions near the outer surface. Beacause the fission chamber was not co...
Tong-Hua, Zhu; Xin-Xin, Lu; Rong, Liu; Zi-Jie, Han; Li, Jiang; Mei, Wang
Fission Enhanced diffusion of uranium in zirconia N. Brerd, A. Chevarier, N. Moncoffre,
Fission Enhanced diffusion of uranium in zirconia N. BĂ©rerd, A. Chevarier, N. Moncoffre, Institut and Fission Enhanced Diffusion (FED) of uranium into zirconia, representative of the inner face of cladding temperature is measured by an IR pyrometer. A model is proposed to deduce an apparent uranium diffusion
Paris-Sud XI, Université de
Dispersion of the Neutron Emission in U{sup 235} Fission
DOE R&D Accomplishments (OSTI)
Equations are developed which allow the calculation of the average number of neutrons per U{sup235} fission from experimental measurements. Experimental methods are described, the results of which give a value of (7.8 + 0.6){sup ?} neutrons per U{sup 235} thermal fission.
Feynman, R. P.; de Hoffmann, F.; Serber, R.
A process is given for removing plutonium and/or fission products from uranium fuel. The fuel is dissolved in molten zinc--magnesium (10 to 18% Mg) alloy, more magnesium is added to obtain eutectic composition whereby uranium precipitates, and the uranium are separated from the Plutoniumand fission-product- containing eutectic. (AEC)
Martin, A.E.; Johnson, I.; Burris, L. Jr.; Winsch, I.O.; Feder, H.M.
Nuclear decay heat -the energy released by fission fragments A.A. Sonzogni and M. Herman
Nuclear decay heat - the energy released by fission fragments A.A. Sonzogni and M. Herman National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY 11973 Decay heat is an important issue that has to be dealt with after a nuclear reactor is shut down. Following the fission of an actinide
Fission Cross Section Calculation Using TALYS Based on Two Different Level Density Models
Fission cross sections in statistical model of fission are calculated using one of important parameter such as transmission coefficients. This parameter calculated using optical model parameter and level density. There are several models of level density that can be used to predict fission cross section. They are Constant Temperature Model, Fermi Gas Model, Back-Shifted Fermi Gas Model, and Generalized Superfluid Model. In this work, fission cross section would be calculated using two different model of level density, such as Constant Temperature Model Plus Fermi Gas and Generalized Superfluid Model on Th-232 (n,f) fission reaction. Calculation result from two different model then would be compared with experimental data from ENDF B/VI. Analysis of result would lead to the conclusion of spesific characteristic for each model in every fission cases. This work has became a preliminary study to calculate fission cross section using different set of level density models. Further work will be implemented to calculate similar fission cross section using level density parameter that approximated by Thermal wavelength [see 21].
Kurniadi, R.; Basar, K.; Waris, A. [Nuclear Physics and Biophysics Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung 40132 (Indonesia); Perkasa, Yudha S. [Department of Physics, Jl. Ganesa 10 Bandung 40132 (Indonesia); Nuclear Physics and Biophysics Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung 40132 (Indonesia)
A fission-fusion hybrid reactor in steady-state L-mode tokamak configuration with natural uranium
The most prevalent criticism of fission-fusion hybrids is simply that they are too exotic - that they would exacerbate the challenges of both fission and fusion. This is not really true. Intriguingly, hybrids could actually ...
DataTrends Water Use Tracking
Use Tracking Use Tracking Organizations across the country are measuring and tracking the water use of over 50,000 buildings using the U.S. Environmental Protection Agency's (EPA) ENERGY STAR Portfolio Manager. These buildings represent close to 20% of all buildings in Portfolio Manager. EPA has prepared the DataTrends series to examine trends in energy and water consumption in Portfolio Manager. This document presents the general trends seen in the water data. To learn more, visit www.energystar.gov/DataTrends. Many different types of organizations are tracking water consumption in a wide variety of buildings located in all 50 states. The most common types of buildings with water data are
Turkey Track Wind Farm | Open Energy Information
Track Wind Farm Track Wind Farm Jump to: navigation, search Name Turkey Track Wind Farm Facility Turkey Track Wind Farm Sector Wind energy Facility Type Commercial Scale Wind Facility Status In Service Owner CanTex Energy Developer Wind Tex Energy LP Location Nolan TX Coordinates 32.23182529°, -100.043478° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":32.23182529,"lon":-100.043478,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Spin tracking in RHIC (Code Spink)
The evolution of the spin during acceleration in the Relativistic Heavy Ion Collider (RHIC) has been studied with a new numerical code, Spink. Results of spin tracking through resonances are shown.
Luccio, A.U.
Visual Tracking of Real World Objects
This paper describes the progress made towards tracking an object visually using a PIN diode attached to a dual mirror deflection system which enables the PIN diode to "optically point" to any position in two-space. A ...
Speckert, Glen
Robust adaptive subspace extraction for DOA tracking
This paper addresses the problem of extracting a time-varying signal subspace from noisy signal measurements for direction-of-arrival (DOA) estimation and tracking. A robust adaptive method for extracting the signal subspace is developed based on robust ...
Dekun Yang; S. J. Flockton
Tracking Algorithm for Multi- Dimensional Array Transposition
He, SC2002 1 MPI and OpenMP Paradigms on Cluster of SMP Architectures: the Vacancy Tracking Algorithm for Multi- Dimensional Array Transposition Yun (Helen) He and Chris Ding...
Feature Tracking on the Unit Sphere
Techniques used in a previous study of the objective identification and tracking of meteorological features in model data are extended to the unit sphere. An alternative feature detection scheme is described based on cubic interpolation for the ...
New Web Service Tracks Foreign Tech Regulations
New Web Service Tracks Foreign Tech Regulations. ... To learn more—and to sign up—go to the Notify US Web site at www.nist.gov/notifyus.
TRUSS: Tracking Risk with Ubiquitous Smart Sensing
We present TRUSS, or Tracking Risk with Ubiquitous Smart Sensing, a novel system that infers