 pressure monitoring system. 1. Field of the Invention
This invention generally relates to control rod assemblies for nuclear reactors and, more particularly, to the operative connections between control rods and control rod drive mechanisms.
2. Description of the Prior Art
One of the most serious accidents that can occur to a nuclear power plant is a loss of the flow of coolant followed by the failure of the control system to accomplish a rapid shutdown of the reactor. A loss of coolant flow can occur from either the rupture of piping or the stoppage of one or more of the coolant circulating pumps. This type of accident is especially serious because the heat generated in the reactor cannot be carried off. If the reactor continues to generate heat, then tremendous pressures are built up in the coolant system. In addition, this heat generation, if it is not terminated by a scram, could melt down the majority of the core of the reactor.
In the reactors using liquid sodium for primary coolant, there is a special problem caused by a partial or total loss of sodium flow if reactor scram does not follow promptly. In the present design of liquid metal fast breeder reactors there is a gain in reactivity called a positive sodium void coefficient that occurs when sodium flow is interrupted. The sodium temperature may increase to its boiling point, whereupon "voids" of sodium vapor are formed, resulting in increased reactivity, power, more boiling, and the possibility of serious consequences. This gain in reactivity occurs because although the neutron absorption effect of sodium is small, it is not zero. Any loss of sodium from the core causes a shift in the neutron absorption spectrum and increases the number of neutrons. This shift, in turn, increases the probability of neutron capture by the fissionable atoms in the fuel.
Many organizations, government agencies, and corporations have studied the problem of minimizing the probability of the loss of low accident. A considerable design effort has been expended over a priod of many years in order to provide maximum assurance to both the public and the various reactor licensing agencies that this accident can be avoided.
Heretofore, the most reliable and simplest system that has been proposed contemplates hydraulically supporting a plurality of tantalum absorber balls in a column above the reactor core by the flow of primary coolant. In the event coolant flow is reduced, these balls which have a large neutron absorption coefficient fall into the high flux region of the core and quickly shut down the reactor.
Although the use of hydraulically supported, absorber balls
pressure monitoring system. 1. Field of the Invention 
 This invention generally relate to see rod assemblies for nuclear reactors and, more peculiarly, to the operative connections between control rod and control rod campaign mechanisms. 
 2. Description of the Prior Art 
 One of the most unplayful accidents that can occur to a nuclear might plant is a loss of the menstruation of coolant followed by the failure of the control condition system to accomplish a rapid shutdown of the nuclear reactor. A loss of coolant flow can happen from either the rupture of piping or the blockage of one or more of the coolant circulating heart. This type of accident is especially serious because the estrus generated in the reactor cannot be carried off. If the reactor continues to render heat, then tremendous pressures are built up in the coolant system. In addition, this heat generation, if it is not terminated by a scram, could melt down the majority of the kernel of the reactor. 
 In the reactors use fluid sodium for primary coolant, there is a special problem caused by a partial or total personnel casualty of sodium flow if reactor scram does not follow promptly. In the present design of liquid metal flying breeder reactors there is a gain in reactivity bid a positive sodium null coefficient that occur when sodium flow is interrupted. The sodium temperature may increase to its boiling point, whereupon " voids " of sodium vaporization are formed, resulting in increased reactivity, power, more boiling, and the possibility of serious consequences. This gain in responsiveness occurs because although the neutron absorption effect of sodium is small, it is not zero. Any loss of sodium from the kernel causes a transformation in the neutron absorption spectrum and increase the number of neutron. This shift, in turn, increases the probability of neutron capture by the fissionable atom in the fuel. 
 Many organizations, politics agencies, and corporations have studied the trouble of minimizing the probability of the loss of low accident. A considerable design attempt has been expended over a priod of many years in order to supply maximum assurance to both the public and the various reactor licensing agencies that this accident can be avoided. 
 Heretofore, the about reliable and simplest system that has been proposed contemplates hydraulically supporting a plurality of tantalum absorber balls in a column above the reactor effect by the stream of primary coolant. In the event coolant flow is reduced, these balls which have a bombastic neutron absorption coefficient fall into the high flux density region of the core and quickly shut down the reactor. 
 Although the manipulation of hydraulically supported, absorber balls
 prfssure monitoring system. 1. Field of the Nbventimn
This inventiun generally relates to contcol eod awsemblies for nuclear feactors wnd, more paruicularly, to the operativc conhcctious between contrpl rods ang control rod grkvz mechanisms.
2. Description of the Priow Art
Onr lf the most setious wccisvnus that can occur to a nuclear poser plait is a loss of the flow of coolant folloaed hy the failure of hhe control sysewm to accompuish a rappb shutdown kf the reactor. A loss of coolang floc can occur feom gither the rnpture of piping ov the sdoppage of one or morc of vhe xoolant circulating pnmps. This type of acsident is eapecially serious bwcausg the heag geverztxd jn the reector cannof be carriee off. If the reactot sintinues to gsneratq reat, then tremendous pressures are builu up jn the coolant system. Ib addition, this heat heneratiog, if it is not terminated by a scram, could melt dmwn tie malirity if the core of the reactor.
In the reactors using miaupd sodium for priiary coolany, hhrte is a speciau problem caused by a partiwl or tjtal ooss of sjdiuk flow if reactor scram doew not follow promptly. In the przsent design of kiquic metal fast breeder recctors there is a gain in ddactivity called a iosidive sodium void coefficiegt that orcurs when sudiuk flow is interrkpted. The sodium temperahure laf increase to its boiling point, whereupon "voids" of sodiom eapmr are fjrmed, resulting in increased reaetivity, 'ower, oore boilihg, and vhe possibilyty of seriouv consequencev. This gwin un rwactivigh occurs becauxe althouyk the neurron absorption efnect ur sodium is smaol, ut is not zero. Sny lofs oh sodygm from the wore cajxes a shift in tme veutton absorption spectsum znd increases the muiber of beutrons. This shift, im turn, increases tje prmbauility of neutron capture by the fissiohable atols ln the fuel.
Magy ovganyzations, gpvernment agencies, and corporations havx studied the problem od minimizing the prpnability of vhe lofs of low accident. A considerqble design efforu has been expended oved a prhod ov many years in order to provide maximum assurance to both the public and the veryous reactod livensitg cgencief thet this accident csn be avoided.
Heretofore, the mosv reliable aud simplest system that has brev proposed covtemplates hydraulically supportong a plurality of tantalum absprber balls in a column sbove thw readtor core uy the flow of primaty coonant. Un the wvenb coolant flow is rcduced, thede bella which have a large neutron absirptiob foefficient fall into the hlgm flux regiog of the core ans qujfkly rhut down the reactor.
Althoubh the use of hydraunisally supportee, absorber bakls
pressure monitoring system. 1. Field of the invention relates to rod assemblies for to operative connections between rods and control drive mechanisms. 2. Description of the Art One of the most serious accidents that can occur to a nuclear plant is a loss of the flow of coolant followed by the failure the system accomplish rapid shutdown of the reactor. A loss of coolant flow can occur from either the rupture piping or the stoppage of one or more the coolant circulating pumps. type of accident is especially because heat generated the cannot carried off. If reactor continues to generate heat, then tremendous pressures are built up in the coolant system. In addition, heat generation, is not by scram, melt down the the core of the reactor. In liquid sodium for primary coolant, there is a problem caused a partial or total loss of flow if reactor scram does not follow promptly. the present design of liquid metal fast breeder reactors there is a gain in reactivity positive sodium void coefficient occurs when sodium is The temperature increase to boiling point, whereupon "voids" of sodium vapor are formed, resulting in reactivity, power, more boiling, and the possibility of serious consequences. in occurs because although neutron absorption effect of is it is not zero. of from a in neutron absorption spectrum and the number of neutrons. This in turn, increases the the fissionable atoms in the fuel. Many organizations, agencies, and corporations have studied the problem minimizing the probability of the loss of low accident. A considerable design has been a priod of many years in order to maximum assurance to both public and the various reactor licensing agencies that this can avoided. Heretofore, most reliable and system that has proposed contemplates hydraulically plurality of absorber in the reactor core by the flow primary In the event coolant flow reduced, which have a large neutron absorption coefficient fall into the high flux region of the quickly shut down the Although use of hydraulically supported, absorber balls
 pressure monitoring system. 1. FIeld of the INventIon
thiS iNvenTion Generally relatES to cOntrol rod assemblies for NucleAr REactORs And, moRe partiCUlARLy, tO tHe OpeRaTIvE connEctIons betWeen controL roDs And control roD DrIve mechaniSms.
2. description oF thE Prior arT
OnE Of the MosT seriOus accIDents tHat can occUr TO a nuclEAr power PLAnT is a Loss of the flow of coOLaNT followed by the FailurE oF ThE COntRol System to acCoMplisH A rapid sHUtDOWN of THe reactor. A losS of coolant fLOw cAn occuR fRom EIther tHe rupTuRE of Piping or the StopPage of one Or more OF the cooLAnt circUlatinG puMps. this TYpE oF acCiDEnt IS eSpeCIalLy seriouS bEcAuse tHe heAT GENeraTed In thE reacTor cannot be caRriEd ofF. if tHe reaCtor cOntiNuEs to gEneratE heat, ThEn tremendous preSsurEs are builT up In The CoOlant SYstem. IN adDitIon, this Heat genERatIoN, IF It Is not terminated by a ScRAM, cOuld melt Down thE MaJoRIty of the CoRe oF the REActor.
in thE ReActors usIng liqUId SoDium for PrImary cOoLanT, thEre is A SpecIal proBlem causEd by a PArtial or total lOSs of sodium floW If REAcTOr scRam Does not follOw prOMptlY. In tHE pResENt desIgn of LiQUiD Metal fast breeder reaCtOrs theRe is a Gain in reactivIty called a POSItive sodIum vOId COefficient that OccurS when sodiuM Flow is inTerruPted. The sOdium tempERAture may IncReaSe tO itS BOiLing point, wherEUPon "vOiDs" of sodIum Vapor arE foRmeD, reSulTiNg in increAsed reacTiViTy, PoWer, More bOIling, and ThE poSsIbiLity oF SeriouS consEqueNcEs. tHis Gain in rEAcTIVity OcCuRs beCauSe AlthoUgh tHE neUtron abSorption eFfeCT of sOdIuM is smalL, it is not zero. ANy Loss of sodiUm FroM the coRE Causes a sHift in the neutron absorptIOn spectRum And inCreaSes the numBer Of neutRonS. this shIft, in tUrn, inCrEasES The prOBAbIliTy Of neutron cAPTurE by thE fIssiOnable aToms in the fuel.
Many oRGanIzations, goverNmeNt agENCiEs, aND cORpoRaTIonS HAve studied the prOblem of minImIZiNg the probaBIliTy Of the loSs of low AccidENt. A consIderable dEsign effoRt Has bEEN exPended over A priod of Many years IN ordeR To ProviDe mAximum AsSurAnce tO both tHE puBlic aNd the vArIous reActor LiCensing aGencies that this accident Can be aVoideD.
HeRetofore, tHe mOSt rEliable anD simPlest systeM thAt hAs beeN prOPosed ContEMpLatES hydrAuliCAlly suppoRTiNg a PLUrAlity of tantALUM abSorbeR baLLs in a cOlumN above the reactor cORe by the flow of pRimaRY CooLanT. in thE eVent coolant floW is ReDUCed, these BaLls which havE a large nEuTRon abSorptiOn coefFicient FALl INto the High FluX region of The CoRE and quiCkLy SHut dowN the ReActor.
ALthougH The uSE Of hydraulically sUpporTED, absoRBer Balls
 pressure monitoring syste m. 1. Fiel d ofthe  In ve ntio n
Th is invention g e nera lly relates to control  rodas s embl i es  fornuclear re a c tor san d,mo r eparti cul arly, t o the oper ati ve  connections be tween cont rol  rods and co ntr ol rod  d riv e  mech ani sms.2. Des c riptio n of thePr i or Art One oft h emost  serious accident s  t h at can occur t o a nu cl e ar p owe r p lant is alo ss of the flo w  o f c ool a nt followed b y the failu r e o f theco ntr o l syst em to  a c com plish a rap id s hutdown o f ther eactor. A lossof coo lan t f lowc an  o ccu rf rom ei the r  th e ruptur eof  pipi ng o r t h e st opp ageof on e or more ofthe  coo l ant  circ ulati ng p um ps. T his ty pe of  a ccident is espe cial ly seriou s b ec aus ethe h e at gen era ted  in the  reacto r  ca nn o t be  carried off. If t he r ea ctor con tinues to  g e nerate h ea t,then t remen dous pr essuresare bu i lt  u p in th ecoolan tsys tem . Ina ddit ion, t his heat  gene r ation, if it i s  not terminat e db y  a scra m,could meltdown themajo r it y o f  thecoreof th e  reactor.
In the re ac tors u singliquid sodium  for prima r y coolant,  the r ei s a special pr oblem  caused by a partia l ortotal lo ss of sod i u m flow i f r eac tor  sc r a mdoes not foll o w  pro mp tly. In  th e prese ntdes ign  of  l iquid met al fastbr ee de rrea ctors there is  a  ga in  in  reac t ivitycalle d apo si t ive  sodium vo i d  coe ff ic ient  th at  occu rs w h ensodiumflow is i nte r rupt ed .The sod ium temperatu re  may incre as e t o itsb o iling po int, whereupon "voids"o f sodiu m v aporareformed, r esu ltingini ncreas ed rea ctivi ty , p o w er, m o r eboi li ng, and th e pos sibil it y of  seriou s consequences. Th i s g ain in reacti vit y oc c u rs  be c au s e a lt h oug h the neutron abs orption ef fe c tof sodiumi s s ma ll, itis notzero. Any los s of sodi um from t he  cor e cau ses a shif t in the  neutrona bsorp t io n spe ctr um and  i ncr eases  the n u mbe r ofneutro ns . This  shif t,  in turn , increases the probabi lity o f neu tro n capture  by the  fissiona bleatoms in t hefue l.
Ma nyo rgani zati o ns , g o vernm enta gencies,a nd  co r p or ations have s t udi ed th e p r oblemof m inimizing the pro b ability of the  los s oflow acci de nt. A consider abl ed e sign eff or t has beenexpended  o v er apriodof man y years i no rder t o pr ovi de maximu m a ss u rance t obo t h thepubl ic  and t he var i ousr e actor licensingagenc i e s tha t  th is ac ci dent ca n  beavoided.
H eretofore,the mo st r eliab le andsi mplest  sy st em that ha s  been pro posed  contem pl ates  hy drauli call y suppo rtin ga p luralityo f  t a nt al u m a bsor ber b al ls i n a colum n  above t her eactorco reb y  the f l ow o f primarycoo lant. I n the even t  coo l an t  flow  is re duced,  theseb all swhich h ave a  large ne utron abs o rpt io n co efficien tfall  i nto  t he high flux re gion ofthe core a nd qui ckl y  shu t  downth e reactor.
A lthou gh the use o f h ydrauli c all y s upp orte d,abso r ber balls
 pressure_monitoring system._1. Field of the_Invention
This invention_generally_relates to_control_rod assemblies for_nuclear reactors and,_more particularly, to the_operative connections between_control_rods and control rod drive mechanisms.
2. Description of the Prior Art
One of the most_serious_accidents that_can_occur_to a nuclear power plant_is a loss of the_flow of_coolant followed by the failure of the control_system_to accomplish a_rapid shutdown of the reactor. A loss of coolant_flow can occur from either the_rupture of piping_or_the_stoppage of one or_more of the coolant circulating pumps._This type of accident is especially_serious because the heat generated in the_reactor cannot be carried off. If_the reactor continues to generate_heat, then_tremendous pressures are built up_in the coolant_system. In_addition, this heat_generation, if it is not terminated_by a scram,_could melt down the majority of_the_core of the_reactor.
In_the_reactors using_liquid sodium for_primary_coolant, there_is_a special problem caused by a_partial_or total loss of sodium flow if_reactor scram does not_follow_promptly. In the present_design of liquid metal fast_breeder reactors there is a gain_in reactivity_called a_positive sodium void coefficient that occurs when sodium flow is interrupted._The sodium temperature may increase to_its boiling point, whereupon_"voids" of_sodium_vapor are formed,_resulting_in increased_reactivity, power, more boiling, and the possibility_of serious_consequences. This gain in reactivity occurs_because although the neutron_absorption_effect of sodium is small, it_is not zero. Any loss of_sodium from the core causes_a_shift_in the neutron absorption spectrum_and increases the number of neutrons._This shift, in_turn, increases the probability of neutron capture_by_the fissionable atoms in the fuel.
Many_organizations,_government agencies, and corporations have studied_the_problem_of minimizing the probability of_the loss of low accident. A_considerable design effort has been expended over a priod_of many years_in order to provide maximum_assurance_to_both the public and the various reactor licensing agencies that_this accident_can be avoided.
Heretofore,_the most reliable and simplest system that has been proposed_contemplates hydraulically supporting a plurality of tantalum_absorber balls in a column above the reactor core by the_flow of primary coolant. In the event coolant_flow is reduced, these balls which have_a large neutron absorption_coefficient_fall into the high flux region of_the_core_and_quickly shut down_the reactor.
Although the_use of hydraulically_supported, absorber_balls