ML17320A414
| ML17320A414 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 02/28/1983 |
| From: | INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG |
| To: | |
| Shared Package | |
| ML17320A413 | List: |
| References | |
| AEP:NRC:0745B, AEP:NRC:745B, NUDOCS 8303080145 | |
| Download: ML17320A414 (23) | |
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ATTACHMENTNO.1TOAEP:NRC:0745BDONALDC.COOKNUCLEARPLANTUNITNOS.1AND2SUMMARYOFNEWANDSPENTFUELSTORAGEARRAYCRITICALITYSAFETYANALYSES8303080145830888PDR*DOCK080003g8PPDR
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~~1.0SU!%MROFCRITYANALYSISK)RDC.QXKENTHJELRACKCriticalityoffuelassembliesinthespentfuelstoragerackispreventedbythedesignoftherackwhichlimitsfuelassemblyinteracticn.Thisisdonebyfixingthezunianseparaticnbetweenassembliesandinsertingneutronpoisonbetweenassanblies.Thedesignbasisforpreventinpcriticalityoutsidethereactoristhat,includinguncertainties,thereisa95percentprobabilityata95percentconfidencelevelthattheeffectivemultiplicationfactor(Kff)ofthefuelassarhlyarraywillbelessthan0.95asreccamendedinANSIN210-1976andin"NK'.PositicnforRevi~andAcceptanceofSpentBzelStorageandHandlingApplication."Xnmeetingthisdesignbasis,scmeoftheconditionsassumedare:fresh15x15Nestinghousecptinuzedfuelassemblies(OFA)of4.05w/oU-235arestored,thepoolwaterhasadensityof1.0gm/cm,thestoragearrayisinfiniteinlateralandaxialextentwhichisnarcreactivethantheactualfinitearray,mechanicalandmethodbiasesanduncert-~tiesareincluded,theminimumpoisonloadingisused,ardforscmeaccidentconditionscreditforthedissolvedboroninthepoolwateristaken.ThedesignrrathodwhichinsuresthecriticalitysafetyoffuelassembliesinthespentfuelstoragerackusestheAMPXsystemofcodesfbrcross-sectiongenerationandKENOXVforreactivitydeterminaticn.Asetof27criticalexperimentshasbeenanalyzedusingtheabovemthcdtodenanstrateitsapplicabilitytocriti-calityanalysisaxxltoestablishthemethodbiasandvariabilitywhicharethenincluded'nthereactivityanalysisoftherack.ThresultoftheaboveconsiderationsisthatthenucleardesignoftherackwillgreettherequirementsofNRCguidelinesandcriteria.
2-0CRITICALITYAISEORD.C.CXXKSPRG'UELCK2-1NEVZIKNNJLTIPLICATIOHFACIORCriticalityoffuelassembliesinthespentfuelstoragerackispreventedbythedesignoftherackwhichlimitsfuelassemblyinteraction.'IhisisGonebyfixingtheminimumseparationbetweenassembliesanRinsertingneutrcnpoiscnbetweenassemblies.Thedesignbasisforpreventingcriticalityoutsidethereactoristhat,includinguncertainties,thereisa95percentprobabilityata95percentconfidencelevelthattheeffectivemultiplicationfactor(Kff)ofthefuelassemblyarraywillbelessthan0.95aseffreccmnendedinANSI5210-1976andin"NRCPositionforReviewandAcceptanceofSpentFuelStorageandHandlingApplications".Thefollowingaretheconditionsthatareassumedinmeetingthisdesignbasis.2.2NORMALSZORAGEa.'Ihefuelassemblycontainsthehighestenrichmentauthorizedwithoutanycontrolrodsaranynoncantainedburnablepoiscnandisat.itsnostreactivepointinlife.CriticalityanalysesweredonefarWestinghouse15x15optimizedfuelassanbly(OFA)withanenrichmentof4.05w/o.'Ihefollowing'ssemblyparameterswerenadeled:NumberofFuelRodsperassemblyRodZirc-4CladO.D.CladThicknessFuelPelletO.D.BmlPelletDensityFuelPelletDishy~RdPitchNurrberZirc-4GuideTubesGuideTubeO.D.GuideTubeThickness2040-422"0-0243"0.3659"955Theoretical1.190%0.5630"Square210.546"0-017" Theassliesareconservativelyreeledwithwaterreplacingtheassemblygridvoluman2noU-234orU-236inthefuelpellet..NoU-235burnupisassumed.b.Thestoragecellnanin-Q.gecmetryisshcamcnFigurel.c.'Ihemoderatorispurewateratthetemperaturewithinthedesignlimitsofthepoolwhichyieldsthelargestreactivity.Aconservativevalueof1.0gm/cmisusedforthedensityofwater-Nodissolvedborcnisincludedinthewater.d.Thennunalcasecalculationisinfiniteinlateralandaxialextent.e.Credit,istakenfortheneutronabsorptioninfulllengthstructuralmaterialsarxlinsolidmaterialsaddedspecificallyforneutronabsorption.'Iheminimumpoisonloading(0.02gm-B10/an)isassumedinthepoisonedcellwalls.AbiasisincludedinthereactivitycalculationtoaccountfortheB4Cparticleselfshielding.g.Abias,withanuncert-~tyisincludedtoaccountforthefactthattheD.C.Cookrackshaverandemcellsclosertogetherthanfortherarninal'design.Theminimumgapbetweenadjacentcellsmaybeassmallas0.953",canparedtothenaninalgapof1.139".IThe.calculationmthoduncertaintyandbiasisdiscussedin'ection2.4.2.3POSHJLATEDACCXDEHISIRx;taccidentconditionswillmtresultinanincreaseinKffofefftherack.Examplesarethelossofcoolingsystans(reactivitydecreaseswithdecreasingwaterdensity)anddroppingafuel 0assemblycntopoftherack.(therackstructurepertinentforcriticalityisnotdeformedandtheassemblyhasmrethaneightinchesofwaterseparatirgit,frantheactivefuelintherackwhichprecludesinteraction).Hmmver,accidentscanbepostulatedwhichauldincreasereactivitysuchasinadvertentdrcpofanassemblybetweentheoutsideperiph-eryoftherackandthepealwall.'Iherefore,foraccidentcondi-tions,thedoublecontingencyprincipleofAHSN16.1-1975isa~lied.'Ihisstatesthatitshallrequiretwounlikely,inde-pendent,concurrenteventstoproduceacriticalityaccident.Thus,foraccidentconditions,the-presenceofsolubleboroninthestoragegxilwatercanbeassumedasarealisticinitialcccxiitim.Thepresenceoftheapproxinately2000pgnboroninthepoolwaterwilldecreasereactivitybynarcthan3(Sb,k.Inperspective,thisisnarcnegativereactivitythanispresentinthepoisonedcellwalls,(i.e.,24%b,k).Therefore,Kfffartherackwouldbelesseffthan0.95evenifthecellwallswereunpoisoned-'IhusKeff~0-95canbeeasilymetforpostulatedaccidents,sinceanyreactivityincreasewillbemuchlessthanthenegativeworthofthedissolvedPorfuelstorageapplications,waterisusuallypresent.~ever,accidentalcriticalitywhenfuelassembliesarestoredinthedryccnditionisalsoaccountedfor.Parthiscase,possiblesourcesofnaderaticn,suchasthosethat'ouldariseduringfirefightingcperations,areincludedintheanalysis.This"optinaxnnaderation"accidentisnotaprobleminpoisonedfuelstorageracks.'Xhepresenceofpoisonplatesraravestheconditionsnecessaryfar"optionnxderation"sothatKffcontinuallyde-"33creasesasrraderatordensitydecreasesfrcm1.0gm/cmto0.0gm/aninpoiscnrackdesigns.
Figure2showsthebehaviorofKffasafunctionofmoderator'ffdensityfaratypicalPNRpoisonedspentfuelstoragerack.12.4MEZHODH)RCRITICALI'IYANALYSIS'Ihecalculationaathodandcross-sectionva1uesareverifiedbycanpariscnwithcriticalexperimentdataforassembliessimilartothosefor~chtheracks'aredesigned.'Ihisbenchmarkingdataissufficient1ydiversetoestablishthatthemethodbiasanduncer-taintywillapplytorackcna9itionswhichincludestrongneutronabsorbers,largewatergapsanilearrxderatordensities.ThedesignmthodwhichensuresthecriticalitysafetyoffuelassembliesinthespentfuelstoragerackusestheAMPXsystanofcodesC'forcross-sectiongenerationandKEHOIVforreactiv-C33itydeterminaticn.The218energygroupcross-section,librarythatistheccrmenstart~pointfarallcross-sectionsusedfarthebenchnarksandthestoragerackisgenerat,edfrunENDF/8-XVdata.'IheNITAWLprogram3includes,inthislibrary,theshelf-shieldedresonancecross-sectionsthatareappropriateforeachparticulargeanetxy.TheNordheimIntegralTreatmentisused.Energyandspatialweightingofcross-sectionsisperformedbytheXSDRNPMexp;amC23whichisaane-LunensionalStransporttheorycode.Thesemulti-groupcross-sectionsetsarethenusedasinputtoKENOIVwhichE33isathree-dimensionalMonteCarlotheoryprogramdesignedforreactivitycalculations.Asetof27criticalexperimentshasbeenanalyzedusingtheabovemethodtodemonstrateitsapplicabilitytocriticalityanalysisandtoestablishthemethodbiasandvariability.'Iheexperimentsrangefrcnwatermoderated,oxidefuelarraysseparatedbyvariousmaterials(Boral,steelandmter)thatsimulateGRfuelshippingandstorageconditions'todry,harderspe~~uraru.unmetalC4,53.cylinderarrayswithvariousinterspersedmaterials(Plexiglass,~C63 steelardairthatdeaenstratet¹wideeofapplicabilityofthemthod.Theresultsandscnadescriptivefactsabouteachofthe27bench-VmarkcriticalexperimentsaregiveninTable1.TheaverageKffofeffthebenchmarksis0.9998whichdenanstratesthatthereisnobiasassociatedwiththemethcd.ThestandarddeviationoftheKffeffvaluesis0.0057dk.The95/95onesidedtolerancelimitfactorfor27valuesis2.26.Thus,thereisa95percent.probabilitywitha95rpercentconfidencelevelthattheuncertaintyinreactivity,duetothemethod,isnotgreaterthan0.0136,k.'Thetotaluncertainty(TU)istobeaddedtoacriticalitycalcula-txcnxs.~=E(ks)method+(~)~~al+(ks)~h3where(ks)~~is0.013asdiscussedabove,(ks),~isthestatisticaluncertaintyassociatedwiththeparticularKENOcalculationheirs.used,(ks)~isthestatisticaluncert-untyassociatedwithrandangapreductionbetweenadjacentstoragecells.Forasinglecanitisfourrithatreactivitydoesnotincreasesignificantlybecausetheincreaseinreactivityduetothewatergapreductionononesideofthecanisoffsetbythedecreaseinreactivityduetotheincreasedwatergaponthecppositesideofthiscan.Theanalysis,fortheeffectofmchanicaltolerances,1xxmer,assumsa"worst"caseofarackccmgosedofanarrayofgroupsoffourcanswherethewatergapbetweenthefourcansisreducedto0.953inch.KEGcalculationsusingthisminimumgapresultinabiasof0-002lldkard.a95K/95Kuncert-styof0.00454.Scnenechanicaltolerancesareratincludedintheanalysisbecauseworstcaseassumptionsareusedinthencminalcaseanalysis.Anexampleofthisiseccentricasseniblyposition.Calculationswere performedwhis~thatthemastreavecxnxU.tionistheassemblycenteredinthecanw'hichisassumedintherxminalcase.Thefinalresultoftheuncm~intyanalysisisthatthecriticalitydesigncriteriaaremtwhenthecalculatedeffectivemultiplicationfactor,plusthetotaluncm~ty(1U)anRanybiases,islessthan0.95.Thesemethodsconformwith'ANSIN18.2-1973,"NuclearSafetyCriteriafcrtheDesignofStationaryPressurizedWaterReactorPlants",MSX5210-1976,"DesignCbjectivesforLNRSpent&elStorageFacilitiesatNuclearPoorerStations",ANSIN16.9-1975,'ValidationofCalculationalMethodsforNuclearCriticalitySafety";HRC1StandardReviewPlan,ardtheNECGuidance,"NRCPositicnfor'Revim:andAcceptanceofSpentKeelStorageandHandlingApplications".2.5CRITICALI'IYRESULTSThespentfuelstoragecellisshowninFi,gurel.'IheminismmBloadieinthepoisonedcellwallsis0.02gm-B/cm.Thesensi-102,t'vityofstorage1tt'mKfftoU-235~ientofthefelassembly,thestoragelatticepitch,andBloadinginthepoisonplatesasrequestedbytheNRCforprisonracksisgiveninFigures3~Forrmrmaloperationandusingtherrathoddescribedintheabovesections,theKfffartherackisdetexminedinthefollcwingeffmanner.:~+B~+B~+B~+221/2 where:K.al=amninalcaseKEHOKffKffbiastoaccountforthefactthatmchanicalefftolerancescanresultinwatergapsbetweenpoisonplateslessthanncminalB~=m~biasdeterminedfrcmbenchmarkcrit.icalccnpari-sonsB=biastoaccountforpoisonparticleself-shieldingks~~=95/95uncertaintyinthencaunalcaeKENTKffks~.=95/95uncertaintyinthecalculationduetoKENOanalysisofmech-micaltolerancesks~~=95/95uncertaintyinthemethodbiasSubstitutingcalculatedvalues,theresultsarethefolly'Lng:Kff092837++00211+00+0025+t(006494)+(004539)22eff+(.013)3=.9482SinceKffislessthan0.95includinguncertaintiesata95/95effprobability/confidencelevel,theacceptancecriteriafarcritical-ityismt.26ACCEPI'ANCECRITERIAFORCRITICALITYTheneutrcnmultiplicaticnfactorinspentfuelpoolsshallbelessthanorecyalto0.95,includinga11uncertainties,underallconditions.
Generally,theacceptancecriteriaforpostulatedaccidentcondi-tionscanbeKff<0.98becauseoftheaccuracyofthemethodsusedeff-Icoupledwiththelearprobabilityofoccurrence.Barinstance,inANSIH210-1976theacceptancecriteriaforthe"optionmcderation"conditionisKff0.98.~ever,forstoragepools,whichcontaindissolvedbore+,theuseofrealistic,initialconditionsensuresthatKff<<0.95forpostulatedaccidentsasdiscussedinSectioneff2.3.Thus,forsimplicity,theacceptancecriteriafarallcondi-tionswillbeKff<0.95.eff 3.0CRI1LITYANALYSISFORO.C.COOKIFUELRACK3.1NEUTRONMULTIPLICATIONFACTORCriticalityoffuelassembliesinthenewfuelstoragerackispreventedbythedesignoftherackwhichlimitsfuelassemblyinteraction.Thisisdonebyfixingtheminimumseparationbetweenassembliestotakeadvantageofneutronabsorptioninwaterandstainlesssteel.Thedesignbasisforpreventingcriticalityoutsidethereactoristhat,includinguncertainties,thereisa95percentprobabilityata95per-centconfidencelevelthattheeffectivemultiplicationfactor(Kff)ofthefuelassemblyarraywillbelessthan0.98asrecommendedinANSIN18.2-1973.'hefollowingaretheconditionsthatareassumedinmeetingthisdesignbasisfortheD.C.Cooknewfuelstorageracks.3.2NORMALSTORAGEa.Thefuelassemblycontainsthehighestenrichmentauthorizedwithoutanycontrolrodsoranynoncontainedburnablepoisonandisatitsmostreactivepointinlife.BecausetheWestinghouse17xl7and15xl5areverysimilarneutronically,onlythe17x17willbeexamined.Sufficientmarginwillbemaintainedto,coveranyreac-tivitydifferences.Theenrichmentofthe17x17Westinghousestan-dardfuelassemblyis4.5w/oU-235withnodepletionorfissionproductbuildup.TheassemblyisconservativelymodeledwiththeassemblygridvolumeremovedandnoU-234andU-236inthefuelpellet.b.Thearrayiseitherinfiniteinlateralextentorissurroundedbyaconservativelychosenreflector,whicheverisappropriateforthedesign.Thenominalcasecalculationisinfiniteinlateralandaxialextent.Calculationsshowthatthe'initerackislessreac-tivethanthenominalcaseinfiniterack.Therefore,thenominalcaseofaninfinitearrayofcellsisaconservativeassumption.2407F:6 c.Nechanica1uncpietiesandbiasesduetomac!ica1to1erancesIduringconstructionaretreatedbyeitherusing"worstcase"condi-tionsorbyperformingsensitivitystudiestoobtaintheappropriatevalues.The~temsincludedintheanalysisare:-stainlesssteelthickness-cellID-center-to-centerspacing-asymmetricassemblypositionThecalculationmethoduncertaintyandbiasisdiscussedinSec-tion4.d.Creditistakenfortheneutronabsorptioninfulllengthstainlesssteelstructuralmaterial.3.3POSTULATEDACCIDENTSMostaccidentconditionswillnotresultinanincreaseinKeffoftherack.Anexampleisthedroppingofafuelassemblyontopoftherack(therackstructurepertinentforcriticalityisnotdeformedandtheassemblyhasmorethaneightinchesseparatingitfromthe.activefuelintherestoftherackwhichprecludesinteraction).However,accidentscanbepostulated(underfloodedconditions)whichwouldincreasereactivitysuchasinadvertentdropofanassemblybe-tweentheoutsideperipheryoftherackandpoolwall.Therefore,foraccidentconditions;-=thedoublecontigencyprincipleofANSN16.1-1975isapplied.Thisstatesthatitisunnecessarytoassumetwounlikely,independent,concurrenteventstoensureprotectionagainstacriti-calityaccident.Thus,foraccidentconditions,theabsenceofwaterin-thestoragepoolcanbeassumedasarealisticinitialconditionsinceassumingitspresencewouldbeasecondunlikelyevent.2407F:6 Theabsenceofwatinthestoragepoolguaranteesubcriticalityforenrichmentslessthan5w/o.ThusanypostulatedaccidentsotherE13thantheintroductionofwaterintothestorageareawillnotprecludethepoolfrommeetingtheKeff<0.98limit.Becausethemostlimitingaccidentistheintroductionofmoderationintothestoragepool,thisaccidentwillbeconsideredindeterminingthemaximumKffforthestoragepool.Forthisaccident,possibleeffsourcesofmoderation,suchasthosethatcouldariseduringfirefight-ingoperations,areincludedintheanalysis.This"optimummoderation"accidentisnotaprobleminnewfuelstorageracksbecausephysicallyachievablewaterdensities(caused,forinstance,bysprinklers,foamgeneratorsorfognozzles)areconsiderablytoolow(<<0.01gm/cm)toyieldKvalueshigherthanfulldensitywater.Theoptimumachievablemoderationoccurswithwaterat1.0gm/cm.Pre-ferentialwaterdensityreductionbetweencells(i.e.,boilingbetweencells)ispreventedbytherackdesign.3.4METHODFORCRITICALITYANALYSIS'IThemostimportanteffectonreactivityofthemechanicaltolerancesisthepossiblereductioninthecenter-to-centerspacingbetweenadjacentassemblies.-ThenominalgapbetweenadjacentcellsforD.C.Cookis11.0inches.Thedesignalsoguaranteesthattheaveragecenter-to-centerstoragecellspacingforamoduleofcellswillbe21.0inches.(SeeFigure4).Therefore,anyreductionofcell-to-cellgapononesideofacanwillproduceagapincreaseontheoppositesideofthecan-TheKENOmodelforthegapreductionanalysisconsistsofaninfinitearrayofclustersof4cellswiththegapbetweenadjacentcellsineachclus-terreducedto10.97inches.Anothercenter-to-centerspacingreductioncanbecausedbytheasym-metricassemblypositionwithinthestoragecell.Theinsidedimensionsofanominalstoragecellaresuchthatifafuelassemblyisloadedintothecornerofthecell,theassemblycenterlinewillbedisplacedJ2407F:6 only0.284inchesfQthecellcenterline.Thisnsthatadjacentasymmetricfuelassemblieswouldhavetheircenter-to-centerdistancereducedby0.568inchesfromthenominal.Analysisshowsthatthecombinedeffectoftheworstmechanicaltoler-ancesandtheasymnetricassemblypositioningmayincreasereactivityby0.00lhk.Thiswillbetreatedasabiasalthoughtheindividualdevi-ationswillberandom.Thefinalresultoftheuncertaintyanalysisisthatthecriticalitydesigncriteriaaremetwhenthecalculatedeffectivemultiplicationfactor,plusthetotaluncertainty(TU)andanybiases,islessthan0.98.ThesemethodsconformwithANSIN18,2-1973,"NuclearSafetyCriteriafortheDesignofStationaryPressurizedWaterReactorPlants",Section5.7,FuelHandlingSystem;ANSIN16.9-1975,"YalidationofCalculationalMethodsforNuclearCriticalitySafety".3.5CRITICALITYANALYSISFORRACKDESIGNFornormaloperationandusingthemethodintheabovesection,theKfffortherackisdeterminedinthefollowingmanner.effIK=K'+B+B+effnominalmechmethodnominalmethod~Where:nominalnominalcaseKENOKeffmechKffbiastoaccountforthefactthatmechanicalefftolerancescanresultinspacingsbetweenassemblieslessthannominal2407F:6 Bmethodme~biasdeterminedfrombenchmcritica1compari-Isonsnominal95/95uncertaintyinthenominalcaseKENOKffks=95/95uncertaintyinthemethodbiasSubstitutingcalculatedvaluesintheorderlistedabove,theresultis:Kff=0.9189+0.0010+0.0+f.(.0062)+(.013)]=.9343effSinceKeffislessthan0.98includinguncertaintiesata95/95pro-bability/confidencelevel,theacceptancecriteria'orcriticalityismet.2407F:6 REFERENCES1.M.E.FordIII,etal,"A218-GroupNeutronCross-SectionLibraryintheAMPXMasterInterfaceFormatforCriticalitySafetyStudies,"ORNL/CSD/TM-4(July1976).2.N.M.Green,etal,"AMPX:AModularCodeSystemforGeneratingCoupledMultigroupNeutron-GammaLibrariesfromENDF/B,"ORNL/TM-3706(March1976).3.L.M.PetrieandN.F.Cross,"KENOIY-AnImprovedMonteCarloCriti-calityProgram,"ORNL-4938(November1978).4.S.R.Bierman,etal,"CriticalSeparationBetweenSubcriticalClus-22tersof2.35wtXUOEnrichedUORodsinMaterwithFixedNeutronPoisons,"BattellePacificNorthwestLaboratoriesPNL-2438(October1977)-5.S.R.Bierman,etal,"CriticalSeparationBetweenSubcriticalClus-tersof4.29wt'XUOEnrichedVORodsinMaterwithFixed22NeutronPoisons,"BattellePacificNorthwestLaboratoriesPNL-2614(March1978).6.J.T.Thomas,"CriticalThree-DimensionalArraysofU(93.2)-MetalCylinders,"NuclearScienceandEngineering,Volume52,pages350-359(1973).7.LetterNo.AEP:NRC:00105datedNovember22,1978..2407F:6
BENCHMhBKCRETXCALEXPERIMIKIS2~3~4~5~6.7~8.9~10.12.13.14.15.16.17.18.19.20.21.22.23~24.25'6.27.UmetalcylinersGeneralM2rodlatticeUO2rcdlatticeUO2rodlatticeUO2rodlatticeUO2rodlatticeUO2rcdlatticeU)2rodlatticeUO2rcdlatticeUO2rcdlatticeUO2lcdlatticeUO2rcdlatticeUO2rcdlatticeUO2rodlatticeUO2rodlatticeUO2rodlatticeUmetalcylinersUmetalcylinersUmetalcylinersUmetalcylinersUmetalcylinersUmetalcylinersUmetalcylinersUmetalcylinersUmetalcylinersUmetalcylinersUmetalcylinersEnrichmentw/oV2352.352.352.352.352.352.352.352.352.352.352.354.294.294.294.2993.293.293.293.293.293.293.293.293.293.293.293.2ReflectorwaterwaterwaterwaterwaterwaterwaterwaterwaterwaterwaterwaterwaterwaterwaterbareparaffinbareparaffinbareparaffinbareparaffinbareparaffinbareSeparatingMaterialwaterwaterwaterwaterstainlesssteelstainlesssteelstainlesssteelstainlesssteelboralboralboralwaterstainlesssteelstainlesssteelboralairairairairairairplexiglassplexiglassplexiglassplexiglasssteelplexiglass,steelCharacterizingSeation(cm)11.928.396.394.4610.4411.477.767.426.349-035.0510.649.768.086.7215.4323.8419.9736.4713.74'.23.4815.7424.4321.7427.9414-7416.671.004+0.993+1.005+0.994+1.005+0.992+0.992+1.004+1.005+0.992+1.001+0.999+0.999+0.998+0.998+0.998+1.006+1.005+1.001+1.005+1.005+1.010+1.006+0.999+0.994+1.000+0.996+.004.004.004.004.004.004.004.004.005.005.006.005.003.00$.004-003.004.003.004~003.005.003.003 tlIrI>++gI~iI~$IPw+IL~EiIIII FIGU2K~~VS.hVTERYiODERAQeffFORATYPICAL"POISONED"SPENTFUELSTORAGERACK'1.00.9eif0.80.70.6TYPEOFRACKC-C,10.25INCHPOISONLOADING,0.02gm-B/cm102FUEL,3.5M/0M17x1700.20.40.60.81.0MODERATORDENSITY(gm/cm)~0-'
~I~IU.KerfASAFUt>CTIOHOFC-CSPACING,,POILOAOIt(GCttDEt<RICHNEhTFOltdSTItsut{OUSE15x15OFAFUELFORO.C.COOKSPEtlT.FUELRACK1.0C-CSPACING.98POISONLOADING.96ENRICHiMENT.94.92.90.88~v<tsi3.55-Pn>>ck~pnO(/o)-4.0510.0-9P-"<<~~Q-C(-Q~z)-10.50.01-L,>~~y(~-8'/z-3-0.02Forenric'r,;-,.antc~r.e,C-C=10.5",lo=ding=Forspacingcurve,w/o=4.05,loading=0.02Forloadingcurve,w/o=4.05,C-C=10.5"20.,02c.---B/cm,".Ia/,24.5511.00.03 FIGURE4STRUCTUREBARSINTERi'MEDIATELYSPACED(NOTINCLUDEDINKENOi%0EL)REFLECTIVEfANGLEIRONS(FULLLENGTH)0.25"0.25"~I,lFUELASSEMBLY17x17MSTD.8.432".I9.0"21.0"