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DC Cook Unit 2 Low Temp Overpressure Protection Sys Setpoint Evaluation.
	ML17329A067
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Issue date:	06/30/1989
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9206270146 9PF'DRADOCK05000315PDROA~>AMERICA'N ELECTRICPOWERSERVICECORPORATION gAPPROVEDtNGENERALC1APPROVEDEXCEPTASNOTEDClNOTAPPROVEDCIFORREFERENCE ONLYD.C.COOKUNIT2LOWTEMPERATURE OVERPRESSURE PROTECTION SYSTEM(LTOPS)SETPOINTE'IALUATION JUNE1989MESTENGHOUSE ELECTRICCORPORATION 8921o:1d/OSQBB9

'k$picIM4P,v'IP40&M4jIr'7+4*stkakwt4elf,>}aE<4i,1t4' INDEXSection~PneNo.Introductlone

~~~~~~~~~~~~~~~~~~~e~~~~~~~~e~~~~~e~~~~~~ee~~~~e~~~~~~~~~~eS~1ummaryofResults......................................................S.2 S1.0Description oftheLowTemperature Transients.......................l.l 1~e~.1GeneralOescription..................................,...............1.2 1.2Operation.......................................

1.3.Potential Overpressure Transients...............

1.3.1SummaryofHassInputTransients..........

1.3.1.1Inadvertent SafetyInjection......

1.3.1.2Charging/Letdown FlowHismatch....

-,1.3.2SummaryofHeatInputTransients,.........

"1.3.2.1Actuation ofPressurizer Heaters..

~e~e~~~~~~~~~~~~~~~~1~2~~~~~~~~~~~~e~~~~~~~1~5~~~~e~e~~~~~~~~~~~~ele5~~~~~~~~~~~~~~~~~~~ele5~~~~~~~~~e~~~~~~~~~~le7~~~~~~~~~~~~~~~~~~~el~7~~~~~~~~~~~~~~~~~~~ele71.3.2.2LossofRHRSCooling..........................

1.3.2.3RCPStartupWithTemperature Asymmetry........

1.3.2.4RelativeSeverityoftheHeatInputTransients 1.4SummaryofTransient Evaluation..............................

~~~~~~~~1e8~~en~~~~1~8~~~~e~~le10~~~~~~ele102.0Description oftheLTOPSSetpointAlgorithm.

2.1PressureLimitsSelection.....,.............

~~~~~~~~~~~~e~~~~~~~~~~e2e1e~~e~~~~~~~~~~~~~~~~~~~~2~12.2HassInputConsiderations...,...............

2.3HeatInputConsiderations...................

2.4FinalSetpointSelection....................

~~~~~~~~~~~2e7~~~~~~~~~~~~~~~~~~~~~~~e2e7~~~~~~~~~~~~~~~~~~~~~e~~2~83.0LTOPSSetpointAnalysisforD.C.CookUnitZ.3.1Operational Limits..............,.............

3.2PORVStrokeTime.............................

~~~~~~~~~~~~~~~~~~~~~~e3~1~~~~~~~0~~~~~~~~~e~~~I1302~ee~~~~~~~~~~~~~e~~~~~e3~5~~~~~~~~~~~~~~~~e~~~~~e3e5~~~~~~~~~~~~~~~~~~~~~~~3~6~~~~e~~~~~~~e~~~~e~~~e3~11~~~~~'~~~~~~~~~~~~~~~~3~18~~~e~~~e~~~~~~~~~~~~~~3e19~~~~~~~~~~~~~~~~~~~~~e3~203.3PORVOperation........................,......

3.4HassInputConsiderations....................

3.5HeatInputConsiderations....................

3.6Specifications forHassInputTransients.....

3.7Specifications forHeatInputTransients.....

3.8.Setpoint Evaluation..........................

89216:1d/080889 I'1~~

I'ectionINDEX(Cont'd)~PaeNo.4.0Correlation toHOGLTOPSSetpointHethodology...

4.1HOGHethodology LTOPSSetpoints.................

4.2LOFTRAN/MOG Correlation.........................

4.3ImpactofSteamGenerator TubePlugging.........

~~~~~~~~~~~~~~~~~~~~4~1~~~~~~~~~~~~~~~~~~~~4~1~o~~~~~~~~~~~~~~~~~4~10~~~~~~~~~~~~~~~o~~~4~148S21e:1d/060S89 WggI~g~,SIAe~gr,I!.,=p.~4,--y>~~ip)fjg+g<~"%.ljLVt+;'YflQE,<+4)l

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D.C.COOKUNIT2LOWTEMPERATURE OVERPRESSURE'PROTECTION SYSTEMSETPOINTANALYSISINTRODUCTION USNRCRegulatory Guide1.99Revision2,"Radiation Embrittlement ofReactorVesselMaterials,"

datedHay,1988becameofficialwithit'spublication intheFederalRegisteronJune8,1988.Theguiderevisesthegeneralprocedures acceptable totheNRCstaffforcalculating theeffectsofneutronradiation embrittlement ofthelowalloysteelscurrently usedforlightwatercooledreactorvessels.0AppendixGof10CFRPart50providesthefracturetoughness requirements for'""reactor>pressure vesselsundercertainconditions.

ToensurethattheAppendixGlimitsarenotexceededduringanyanticipated operational occurrence, technical specification pressure-temperature limitsareprovidedduringlowtemperature operations.

Theembrittlement algorithm specified byrevision2ofRegulatory Guide1.99ismoreconservative thanrevision1,andrequiresthattheselimitsbere-calculated.

TheLowTemperature Overpressure Protection System(LTOPS)providesprotection againstexceeding thevesselductility limits,asexpressed bytheAppendixGpressure-temperature limits,duringcoldshutdown, heatup,andcooldown"""'operatio'ns."

'The'limitsresulting fromimplementation ofthenewrevisiontoRegulatory Guide1.99,requiresthattheLTOPSsetpoints bere-evaluated.

Thepurposeofthisreportis,inpart,todocumentthere-evaluation.

Thisreportincludesastudyofthesensitivity oftheLTOPSsetpointonpressurizer PORVopeningtime,andacorrelation thatbenchmarks theresultsoftheanalysistothatofthealgorithm described inthereport"Pressure Mitigating SystemsTransient AnalysisResults"(July1977).ThisreportwaspreparedfortheWestinghouse OwnersGroup(acronymed "WOG")onReactorCoolantSystemOverpressurization byWestinghouse ElectricCorporation.

Thepurposeofthecorrelation istoprovideAmericanElectricPowerCorporation a8921e:1d/060789 S.1 kVsf'tffi 4'4meansofdetermining LTOPSsetpoints equivalent'o thoseobtainedfromthe~~~~~~~~~~~~~relatively sophisticated LOFTRANbasedanalysisdescribed here,byusinga...simple methodology; i.e.,theHOGreport.Thecorrelation remainsvalidaslongascertainplantparameters areunchanged.

Theseare:instrumentation timedelays,pressurizer PORVflowcharacteristics, andpressurizer PORVfullflowC(v).Theorganization ofthisreport,apartfromtheintroductory commentsandthesummarystatement, isinfoursections:

thefirstandsecondsectionsdescribe, respectively, thejustification forthedesignbasistransients andthealgorithm usedforthesetpointanalysis; thethirdsectiondocuments theanalysisspecificto0.C.Cookunit2,andthefourthsectionprovidesthecorrelation totheHOGmethodology referenced intheintroduction tothisreport.SummarofResultsTheresultoftheanalysisissummarized byF1guresS.1andS.2,illustrating, respectively, thedependency ofthemaximumallowedLTOPSsetpointonPORVopeningtimeforreactorvessel'xposures of12EFPYand32EFPY.Aminimumsetpointlimit,forRCPnumber1sealprotection, doesnotexist.Thisisduetothefactthat,giventhe4secondPORVclosuretime,thereisnotenough,separation (whitespace)betweenthesteady-state'pressure-temperature limitandtheminimumRCSpressurerequirements foranRCPstart,toumbrellathepressureswingresulting fromeitheraheatinjection ormassinjection event.Astheclosuretimedecreases, thepressureundershoot wouldbecomelesssevere.Atthecurrent435psigsetpoint, withsinglePORVoperation, thepeakpressurewouldremainbelowtheAppendixGlimitprovidedthePORVstrokeopentimesremainedbelow6.5seconds,withvesselexposures to12EFPY;or3.5seconds,withvesselexposures to32EFPY.FigureS.3providesthecorrelation thatbenchmarks theresultsofthe"LOFTRAN" basedanalysistotheresultsobtainedfromapplication ofthealgorithm described inthe"MOG"report.Thesecurvesareusedtocompensate forsomeoftheconservatisms ornonconservatisms, depending ontheselectedPORVstrokeopentime,inherentintheHOGmethodology.

Thesecorrelations 8921e:1d/060989S.2

'i\'MllI1

~~~~~~~~~~~.areindependent of,AppendixGlimits,andwillremainvalidaslongascertainplantparameters (pressurizer PORVflowcharacteristics andC(v.),andinstrumentation signaldelays)areunchanged.

Utilization ofthecurvesrequiresthattheLTOPSsetpointfirstbedetermined usingthe"MOG"methodology.

AtthePORVopeningtimecorresponding tothatselectedforthe"MOG"calculation, determine the"LOFTRAN" analysissetpointfromtheordinatebylinearlyinterpolating betweenthetwocurvesboundingthepredetermined "MOG"setpoint.

.8921e:1d/060789 S.3

~LFl~goqg@141 Notest1)l4Pressut~lnstrueent Error2)StnglePORVOperetton3)PORVClosureTtne~4.ISec.4)ReectorVesselExposure~12EFPY6sI58.8OeqFRCSTe~p.i85.8OegFFigureS.lPORYLTOPSetpointvs.Ya1veOpeningTimeat12EFPY8921~:1d/060289 S.4 04A.liltt~I.pleiad5.Agf+tl1I' Roice-1)HoPressurelnstrunent Errof2)SinglePORVOperation3)PORVClosureTine~4.8Sec.4)ReactorVesselExposure~32EFPYICC)Sb.bOegFRCSTemp.=,E.,85.bOegFFigureS.2.PORVLTOPSetpointvs.VaIveOpeningTimeat32EFPYd921~:1d/0602S9 S.S F(OIVgr.y5peVIW~ePi,,ittIpC~

M06LTOPSSetpnt(paiq)~FigureS.3LOFTRAN/MOG LTOPSSetpointCorrelation vs.Pressurizer PORVOpeningTimeM21e:1dj060289 S.G a0~r.

1.0 OESCRIPTIQN

OFTHELOWTEMPERATURE PRESSURETRANSIENTS Overpressure protection forthereactorcoolantsystem(RCS)isachievedbymeansofself-actuated steamsafetyvalveslocatedhighinthesteamspaceofthepressurizer.

ThesesafetyvalveshaveasetpressurebasedontheRCSdesignpressureandareintendedtoprotectthesystemagainsttransients initiated intheplantwhentheRCSisoperating nearitsnormaltemperature.

Toavoidbrittlefractureatlowreactorvesselmetaltemperatures, theallowable systempressureisprogressively reducedfromthenominalsystemdesignpressureastemperature isdecreased.

Therefore, supplemental overpressure mitigation provisions forthereactorvesselmustbeavailable whentheRCSandhencethereactorvessel,isatreducedtemperatures.

Thissupplemental protection, utilizing thepoweroperatedreliefvalves(PORYs),.-isknown.astheLowTemperature Overpressure Protection System.(LTOPS).

ThePORVsaredesignedto.limittheRCSpressureduringnormaloperational, transients whenthereactorisatpowerbydischarging steamtothepressurizer relieftank(PRT),thusavoidingtheneedforthecodesafetyvalvesto.function.

The,flowcapacityandstroketimeofthePORVsisselectedtoavoidareactortripduringalargesteploaddecrease.

Inaddition, thevalvesareutilizedforpressurerelief(water,gas,oramixture).

asapartof.theLTOPS,,and whenperforming thisfunctionwillalso.discharge tothePRT.ThesetpointfortheLTOPSfunctionisselectedsothat.if.one,valvefails,.to actuatewhenrequired, the,secondvalvewillbeabletomitigatethetransient.

Normally, whentheRCSisatatemperature below350F,theRCSisopentotheResidualHeatRemovalSystem(RHRS)forthepurposesofremovingresidualheatfromthecore,providing apathforletdowntothepurification subsystem, andcontrolling theRCSpressurewhentheplantisoperating ina.watersolidmode.TheRHRSisprovidedwithselfactuating waterreliefvalvestopreventoverpressurizing thisrelatively lowpressuresystemduetoeventsoriginating eitherfromwithinthesystemitselforfromtransients transmitted fromtheRCS.TheRHRSreliefvalveswillmitigatepressuretransients originating intheRCS,tomaximumpressurevaluesdetermined bythereliefvalvesset89216:1d/0602S9 0,h>~$AV>f-$eH 4pressureplusapressureaccumulation abovethesetpressuredependent ontheliquidvolumemagnitude ofthetransient.

ThelowpressureRHRSisnormallyisolatedfromthehighdesignpressureRCSduringoperation attemperatures above350'Fbytwoisolation valvesinseries.BecauseoftheNRCrequiredautomatic closurefeaturedesignedtopreventinadvertent overpressurization oftheRHRS,spuriousclosureoftheRHRSisolation valvesisacreditable event.TheLTOPSisintendedtoprovideoverpressure mitigation fortheRCS,considering thosetransients whichmightoccurwhentheRHRSisolation valvesareinadvertently closed,thusisolating theRHRSwaterreliefvalvesfromtheRCS.1.1GENERALOESCRIPTION

'~'The"LTOPS'"is'designed'o providethecapability, duringrelatively lowtemperature reactorcoolantsystemoperation, topreventtheRCSpressurefromexceeding 10CFR50AppendixGlimits.TheLTOPSisprovidedinadditiontotheadministrative controlstoprevent,overpressure transients andasasupplement totheRCSoverpressure mitigating functionoftheresidualheatremovalsystemwaterreliefvalves.Thesystemisdesignedwithredundant components toassureitsperformance intheeventofthefailureofanysingleactivecomponent.

Thepoweroperatedrelief.valves locatednearthetopofthepressurizer, together'with'additional actuation logic.fromthewiderangepressurizer

channels, areutilizedtomitigatepotential RCSoverpressure transients whichmightoccur-iftheRHRwaterreliefvalvesareisolatedfromtheRCS.LTOPSprovidestheadditional'relief capacityforthespecifictransients whichwouldnotbemitigated bytheRHRSreliefvalvesandtherebymaintainthesystempressurebelowthelimitsspecified byAppendixGrequirements.

,1.2OPERATION Duringnormalplantheatup,theRCSisopentotheRHRSandisoperatedinawatersolidmodeuntiIthesteambubbleisformedinthepressurizer.

During8821a:1d/060289 Ilt41~tt'IIC~*

l7r~IJ%r')>~.~)~PII--igtheselow-temperature Iow-pressure operating conditions, theLTOPSisarmedandinareadystatustomitigatepressuretransients whichmightoccuriftheRHRSisinadvertently isolated.

Afterthesteambubbleisformedandthepressurizer waterlevelisatits'ormal valueforno"loadoperation, theRHRSismanuallyisolatedfromtheRCSandtheplantheatupcontinues..

Pressuresurgecontrolisprovidedbythesteambubble.tthenthereactorcoolanttemperature hasincreased aboveapresetvalue(152'F,inthecaseofD.C.CookUnit2)theLTOPSisdisarmed.

DuringanormalplantcooJdown, theLTOPSisarmedasthereactorcoolantrtemperature isdecreased belowthepresetvalue.Atthistimethereisasteambubbleinthepressurizer andthewaterlevelisatthenormallevelforno-loadoperation.,

TheRHRShasbeenplacedinservicebyopeningthesuction~isolation valves;thusmakingtheRHRSwaterreliefvalvesavailable to'itigate" ressuretransients.

Rhenthecoolanttemperature hasbeenreducedtoabou160'ytheoperation oftheRHRS,thesteambubblemaybequenchedandthereactorcoolantpumpsstopped.Fromthispointoninthecooldown, theplantiswatersolidandiftheRHRSbecomesinadvertently

isolated, theLTOPSwillbeinanactivestatusreadytomitigatethosepressuretransients thatmightoccur.MhentheRCS,isoperatedinthewatersolidmode,thepressureisautomati-..

callycontrolled bythelowpressure'letdownvalve.in'the=Chemical-andVolumeControlSystem(CYCS).Thisvalvesensesthepressureintheletdownline(refFigure1.1)andmaintains thepressureattheselectedcontrolvaluebythrottling theletdownflowfromtheRCS.Atthistime,thechargingflowintotheRCSissetataconstantvalue.andiscontrolled bythechargingflowcontrolvalve.Itshouldbenotedthat.thepressurebeingcontrolled isthatintheletdownlinewhichthenindirectly controlsthepressureintheRCS.However,ifthepressuredropthroughtheRHRSandthebypasslineintotheCVCSischangedbythrottling ofvalvesorchangingtheflowratethroughtheRHRS,theRCSpressurewillalsochangesincethelocationofthecontrolled pressureisin.theletdownline.8921a:1d/060289 1.3

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ChargingF1'Conlroll~PressurePurlflcatieP0~RIIRRellefYalveRIIRPumpIIXRIIRIIXIIXeCVIICfgI.ethel4PressuretontrolI'igure1.1TypicalLowPressureCoolant/Purification FlogPath892Ie:1d/06078$

'EelII'IgI1;fi'~~-wg0;t 7~~1.3POTENTIAL OVERPRESSURE TRANSIENTS

",Duringlowtemperature operations, reactorcoolantsystemoverpressurization transients canbecausedbyeitheroftwotypesofevents:massinputorheatinput.BothtypesresultinmorerapidpressurechangeswhentheRCSiswatersolid.However,atreactortemperatures below350'F,theRCSmustbealignedtotheResidualHeatRemovalSystemtoremovecoredecayheatandthewaterreliefvalveswillbeavailable tomitigatepressuretransients whichmightoccur.Also,therewillgenerally beasteambubbleinthepressurizer whenthereactorcoolanttemperature isaboveabout150'Fduringplantcooldownsothatwatersolidconditions arelimitedtorelatively lowtemperature conditions.

Therefore, thedescriptions ofthetwotypesoftransients implythattheRCSiswatersolidatalowtemperature.

1.3.1SummarofMassInputTransients 1.3.1.1Inadvertent SafetyInjection Inadvertent actuation ofsafetyinjection eventsincludefullsystem(bothtrains),singletrain,orsinglecomponent withinatrainactuation.

Eachofthethreetypesofeventsarediscussed separately.

Fullsystemactuation wouldincludetheopeningoftheisolation valvesonallSIaccumulators, startupofalllow-headandhigh-head safetyinjection pumpsandisolation of,=;thenormal.letdownpath<to-,theChemical.and

.Volume.ControlSystem.Suchaneventwouldresultinunacceptably largevolumesofwaterbeingforcedintotheRCS.Therefore, sucheventsmustbeprevented bystrictadministrative controls.

Thesecontrolsrequiretheblockingoftheautomatic SIactuation

circuits, immobilizing theSIaccumulator motoroperatedisolation valves,andlockingoutpowertothehigh-head SIpumps.Inatypicalwestinghouse design,thelow-headsafetyinjection pumps(theRHRpumps)arenormallyinoperation andalignedtotaketheirsuctionfromtheRCS,andnotfromtherefueling waterstoragetank,duringlowpressureandlowtemperature plantoperations.

Therefore, evenifaspuriousstartsignalwasreceived, thelow-headSIpumpswouldnotfunctiontoinjectRMSTwaterintotheRCS.8921e:1d/060289 1.5 P,.jg~>Ãi~'II1l':p44Dg+Af-A1IItMC Theprobability ofa'singletrainactuation isaboutthesameasafullsystemactuation, sincethesignalswhichcallforsafetyinjection, bothmanualand'automatic, arenormallyprocessed throughtheengineered safetyfeaturelogiccircuitssuchthatasignal,whetherspuriousornot,willimpactbothtrains.Therefore, sincetheSIsystemisessentially immobilized atlowtemperature, singletraininadvertent actuation isconsidered nomorelikelythanfullsystemactuation.

ForthoseplantdesignsinwhichthechargingpumpsservethesecondfunctionofhighheadSIpumps,e.g.theCookunits,aspurioussafetyinjection signalwouldrealignthevalvingtotransferfromthechargingfunctiontothesafetyinjection function.

Therefore, theoneoperating chargingpumpwhichisnotlockedoutwilldeliverthroughthesafetyinjection flowpathtotheRCS.~'-'~~'~',~-However,,'~the~RHRS.would.

remainopentotheRCSatthistimeandtheRHRSreliefvalveswouldmitigatetheresulting RCSpressuretransient.

Inadvertent actuation ofasinglecomponent wouldrequirethatanoperatorselectively unlocktheelectrical powertothecomponent andthencausethecomponent tobeenergized.

Themostprobablewayforthiseventtooccurwouldbeduringperiodicsurveillance testingrequiredbythetechnical specifications orduringpostmaintenance checkoutofthecomponent.

Deliberate opening'f anSIaccumulator, isolation valvewhile..theaccumulator..

ispressurized withgasisnotconsidered probablebecausethereisnotechnical-'specification",to.test theisolation valvesatshutdown, andprudentmaintenance procedures forthevalveswouldlikelyrequirethatthecompressed gasintheaccumulator beremoved.Postmaintenance checkoutorperiodicsurveillance testshowever,mightbeattempted onahighheadsafetyinjection pumpproviding anopportunity foroperatorerrortocauseaninadvertent singlepumpinjection event.Therefore, asinglesafetyinjection pumpstartupeventduringsurveillance testingorfollowing maintenance

.isconsidered apotential massinputtransient.

SincetheRHRSwouldbeopentotheRCSatthistime,theRHRSreliefvalveswouldmitigatetheresulting RCSpressuretransient.

89216:1d/060289 1.6

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1.3.1.2Charging/Letdown FlowMismatch~~~Charging/letdown flowmismatcheventscanbepostulated tooccurinanumberofways.Onewaywouldinvolvethecompletetermination ofletdown:closureoftheletdowncontrolvalve,isolation oftheRHRS/CVCS crossover path,orclosureoftheRHRSinletisolation valvescausedbymalfunctions ofthecontrolsystems.Asecondwaywouldinvolveanincreaseinthechargingflowbyeitheroperatororinstrument errorsuchthatthechargingflowexceedstheprevailing letdownflow.Themostseveremassinputtransient wouldoccuriftheletdownflowcontrolsfailedtothe.zeroflowcondition whilethechargingflowcontrolsfailedtothefullflowcondition.

Thisfailuremodewouldresultinthemaximum'-"-"'""'"'"charging/'letdown'flow-mismatch eventbutdoesnotresultintheisolation oftheRHRSreliefvalvesfromtheRCS.Therefore, theRHRSreliefvalveswouldmitigatethistransient andpreventanoverpressure condition ineithertheRHRSortheRCS.Themostlikelywaythatacharging/letdown flowmismatchwouldoccurisfortheRHRS(andreliefvalves)tobeinadvertently isolatedfromtheRCSbyspuriousclosureoftheRHRSinletisolation valves.Suchaspuriousclosureiscredible'due'o the-presence'f.::the automatic closing..signal, requiredbytheNRC.SincethisspuriousvalveclosureeventcausesanRCSpressuretransient-by" stopping" the'letdownflowandconcurrently isolatestheRHRSreliefvalvesfromtheRCS,itisconsidered a"designbasis"transient fortheLTOPS.1.3.2SummarofHeatInputTransients 1.3.2.1Actuation ofPressurizer HeatersTheinadvertent actuation ofthepressurizer heaterswhenthepressurizer isfilledsolidwillcauseaslowriseinthewatertemperature withaconsequent increaseinpressureoftheconstantvolumeRCS,iftheinstalled automatic

'ressurecontrolequipment isnotinservice.Sincethepressuretransient is8921e:1d/060269 1.7

~CP<<Son'lllilffv~aabC veryslow,.theoperatorshouldrecognize andterminatethe transient beforeanunacceptable pressureisreached.TheRHRSisopentotheRCSwheneverthepressurizer isfilledsolid,inaccordance withadministrative controls.

Therefore, theRHRSreliefvalveswillbeactuated, negatingtheneedfortheLTOPS,iftheoperatordoesnotintervene andstopthetransient.

Thiscase'snotconsidered significant tothedesignofeithertheRHRSreliefvalvesortheLTOPS.1.3.2.2LossofRHRCoolingAlossofresidualheatremovalcoolingwhilethepressurizer isfilledsolidcouldbecausedbyalossofflowmalfunction inthecomponent coolingwaterortheservicewatersystems,ortheclosureoftheRHRSinletisolation valves."..The continual

.releaseofcoreresidualheatintothereactorcoolant,withnoheatrejection intotheenvirons, wouldcauseaslowriseinthecoolanttemperature andpressure.

Sincethetransient isslow;-theoperatorshouldrespondandeitherrestoretheRHRSvalvestotheiropenposition, restorecooling,orlimittheRCSpressurebyventingthepressurizer.

Thistransient.

isnotconsidered significant tothedesign.of,theLTOPSsinceitisarelatively slowtransient comparedtotheheatinputtransient resulting fromthestartupofareactorcoolantpumpincombination withanRCS/SGtemperature asymmetry.

..'.,1.3.2.3.,RCP.Startup Ni.thTemperature Asymmetry Duringplantheatupandcooldownoperations, typicaladministrative controlsrequirethatatleastonereactorcoolantpumpbemaintained inoperation wheneverthereactorcoolanttemperature isgreaterthan160'F.Therefore, the'argevolumetric

=flowthroughout theRCSwillmaintainanisothermal condition intheRCS.Thesteamgenerator secondary sidewaterimmediately surrounding thetubeswillalsoremainatatemperature nearthatofthecirculating reactorcoolantontheprimaryside.Duringnormalcooldownoperations, whenthereactorcoolanttemperature hasdecreased

'below160'Fthereactorcoolantpumpsmaybestopped.Subsequently, 8921e:1d/060789 1.8 EvP+,vat,@~~+A~!I~,~~Ali~~~<k14eylip"~Itgl4QQi~WF~1 isothermal-conditions maynolongerexist.The-.reactor, coolanttemperature willbedecreased below160'Fbyheatrejection throughtheRHRS.Thesteam'generator contained water(bothprimaryandsecondary) mayremainatarelatively constanttemperature, greaterthantheRCStemperature, duetolittleornocirculation throughihetubes.Therefore, asignificant temperature asymmetry maydevelopbetweentheprimarywatercontained inthesteamgenerator andtherestoftheRCS.Ifareactorcoolantpumpweretobestarted,thesuddenheatinputintothereactorcoolantfromthesteamgenerator wouldcausearapidincreaseinreactorcoolanttemperature.

Iftheeventweretooccurwhilethepressurizer isfilledsolid,arapidlyincreasing pressuretransient wouldoccur.Inaccordance withtypicaladministrative

controls, theplantwillbeunder-water..sol;id;.conditions..only whiletheRHRS.is.inservice,andatleastonereactorcoolantpumpwillbeinoperation atreactorcoolanttemperatures above160'F.Therefore, thistypeofheatinputtransient willbelimitedtoinitialcoolanttemperatures below160'F.Sinceitisnotpractical todetermine arepresentative temperature forthelargestagnantvolumeof-<<secondary waterinthesteamgenerator,,the, operatorwillnotbeawarethatthetemperature maybesubstantially different fromtheremainder ofthereactorcoolant.Fromtheinitialisothermal temperature of160'FwhentheRCPis.stopped,thebulk.reactor.coolanttemperature isunlikelytodecrease...below110'Fwithoutsomeextraordinary coolingmeans,whilethesteam:-<'.=-':"~..

gene'rator..water,.may, remain,near..160'F,...Therefore,.the differential temperature isnotexpectedtobegreaterthan50'Fforthistypeofheatinputtransient.

IftheRHRSisinadvertently isolatedfromtheRCSbyclosureoftheisolation valves,asbjaspuriousoperation oftherequiredauto/close "interlock, while,theplantiswatersolidandinmode4,typicaltechnical specifications requirethatareactorcoolantpumpberestarted withinonehourifanRHRloopcannotbereturnedtoservice.Duringthepotential onehourdelayperiod,atemperature asymmetry inthereactorcoolantlo'ops,duetothecontinued inputofcoldsealinjection water,coulddevelopandnotbeS921e:1d/0602BB 1.9 lP'g~,(sr~yp"y~wp~yIg"~44.=~>aI%~~.$4.~'CCQ+~su.,~mgyjpykpr,,aA

~4apparenttotheoperator.

-Thenwhenthereactorcoolant,pump,is.restarted, an~~increasing pressuretransient willoccurasthecoldwatercontained inthe'steamgenerator/RCP cross"over pipemixeswiththerestoftheRCSwater..1.3.2.4RelativeSeverityoftheHeatInputTransients Figure1.2comparestherelativeseverityofthepressuretransients resulting fromtheheatinputcasesdiscussed inthepreviousparagraphs, asanalyzedfortheHestinghouse OwnersGroup.Fromaninspection ofthefigure,itisevidentthattheheatinputcasesfrompressurizer heatersanddecayheatarelesssignificant thanthoseforthecaseswithaloopasymmetry.

Therefore, theselesssignificant casesarenotconsidered forthesetpointanalysis.

Similarly, theloopseal(cross-over pipe)asymmetry caseisseentoresultin<-a"relative'ly,.small pressuretransient-:compared-,to thepotenti'al excursion possiblefromthesteamgenerator/RCS temperature asymmetry cases.The"designbasis"caseforthesetpointdetermination istherefore thetemperature asymmetry betweenthesteamgenerator andtheRCS.1.4SUMMARYOFTRANSIENT EVALUATION Basedonthepreviousdiscussion, mostoftheidentified massinputandheatinputtransients whichmightoccurwhiletheplantiswatersolid,willbemitigated bythewaterreliefvalvesintheRHRS.However,-for thoseremote"'-"'~"cases~which".occur or~.are.causedby..the.RHRS having,.become

-isolated fromtheRCS,theLTOPSmaybecalledupontomitigatecertainincreasing pressuretransients.

Specifically, theLTOPSdesignbasistransients are:1)themassinputtransient causedbyanormalcharging/letdown flow'mismatch aftertermination ofletdownflow,and2).theheatinputtransient causedbytherestartofaRCPwhentheRHRSisnotopento.theRCS.8921e:1d/060289 1.10

~144III'5JIL~"44twups~ig+4l~E44+><y*'1",S"r>t,:,IIpP0'CJ"4)lYpmksa.pLslq.1

~~SingleRCPatartvitaenoreliefvalveacutataen RCS/S6~l56F/2BBF--4'tA+"fIg'%'whyLoopSaai/RCS'86F/218FCor~OacayHthddttionhtti"Figure1.2RelativeRCSPressureTransients Resulting FromHeatInputEvents$82le:1d/060289 AlIJ,'7

2.0 DESCRIPTION

OFTHELTOPSSETPOINTALGORITHM 4Thedetermination ofthelowtemperature overpressure protection setpointisbasedonalocalversionoftheLOFTRANcode.TheLOFTRANcodepredictsplanttransient thermal/hydraulic behaviorbymodelingthereactorcoolantsystem,including thesteamgenerators, pressurizer (including PORVs),andreactorcoolantpumps,aswellasthecontrolandprotection systems,selectedvalving,and,somebalanceofplantsystems.TwoversionsoftheLOFTRANcodewereutilized:

thefirstversion,usedforthemassinputcalculations, collapses theseveralRCSloopsintoasingle'loopmodel;thesecondversion,usedfortheheatinputcalculation, modelseachloopexplicitly.

Theselection oftheproperLTOPSsetpointrequirestheconsideration ofanumberofsystemparameters.

Amongthesearethefollowing:

1:'Volume'of thereactorcoolantinvolvedinthetransient.

,2.,RCSpressuresignaltransmission delay.3.Volumetric capacityofthereliefvalvesvs.openingposition.

4.Stroketimeofthereliefvalves(openingandclosing).

Ifthepressureundershoot isimportant, theclosuretimeisrequired.

15.'assinputrateintotheRCS.,G.Heattransfercharacteristics ofthesteamgenerators.

7.Initialtemperature

.asymmetry betweentheRCSand,steam generator secondary water.8.Massofsteamgenerator secondary.

water.9.RCPstartupdynamics.

10,RCPNo.1sealdeltaPrequirements.

Important ifalowersetpointlimitistobespecified forRCPsealprotection.

11.AppendixGpressure/temperature limitsforthereactorvessel.2-1PRESSURELIMITSSELECTION ThefunctionoftheLTOPSistopreventtheRCSpressurefromincreasing abovethePORVpiping/structural analysislimitsandthelimitsprescribed bytheallowable pressure-temperature characteristics forthespecificreactorvessel8921e:1d/072089 2.1 C"Qt~1f2%;<<1CFEt~CEa materialin.,accordance, withthe;rules

.givenin.Appendix..G

.to10CFR50.FortheCookunits,aconstantpressuresetpoint, independent oftemperature, isemployedsothatthelimitsconsidered for,thisparticular casemustmeetthemostrestrictive segmentoftheAppendixGcurveswhencomparedtotheoverpressure transient asafunctionmf~perature.

ThePORVpiping/structural limitsarewellabovethosepressures ofconcernhere,'ndaregenerally considerations onlyforthoseplantswhosePORYsetpoints arefunctions oftemperature.

<Qlg~1j'tjlAcharacteristic pressure-temperature relationship isshowninFigure2.1,illustrating theallowable systempressureincreases withincreasing temperature.

Thistypeofcurvesetsthenominalupperlimitonthepressure, whichshouldnotbeexceededduringJKSincreasing pressuretransients.

When-.a'relief.

val.ve".is..actuated tomitigateanmcreasing pressuretransient, thereleaseofavolumeofcoolantthroughthevalvewillcausethepressureincreasetobeslowedandreversedasillustrated byFigure2.2.Thesystempressurethendecreases, asthereliefvalvedischarges coolant,untilaresetpressureisreachedwherethevalveissignalled toclose.Notethatthepressurecontinues todecreasebelowtheresetassureasthevalvecloses.Thenominallowerlimitonthepressureduringthetransient isselectedbased.onarequirement ofthereactorcoolantpumpNo.1.sealtomaintainanominal200psidifferential pressureacrossthesealfaces.'<<'..~.:~>>..The nominal;;upper.."l.hami,t,(basedonthe..minimum

.of.AppendixG, requirements orthePORVpipinglimitations) andthenominalRCPNo.1seallowerlimitIpressurevaluescreateanacceptable pressurerangeintowhichthePORVsetpoints mustbefit.Anillustration oftheselimitsal'ongwiththesetpointselection rangeisshowninFigures2.3and2.4.Intheeventthatthesetpointselection rangeisinsufficient toaccommodate boththeAppendixG,.andtheRCPNo.1seallimit,theAppendixGlimitwilltakeprecedence.

S921e:1d/060789 2.2

)II"*its.gy'I~r'id4,~'ii'Itkt4>$48'iick'laity

%i"icar~*~iPi<

vg2SOO22502000...1'750, 150012SO1000linecceptableOperation IIIIIIIIIIAcceptabl eOperation IIIIIII~IIIIIIIIIIIsIIIIII~II~IIIIIIIIIIIIIIiIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII~IIIIIIIIIIIIIIIIIIIIIIIIIIIIIO4lII~,750500250'-C001dONlRates'F/Hr02040601001IIIIIIIII'II~IIII~IIIII~I050100'502002503001NOlCATED TEK1'ERATURE (DEC.F')FigUre2.1TypicalAppendixGP/TCharacteristics 8921e:1d/060289 2.3

J!v'4rlr<<~it~.-'PA POver'SETPO?RT

-RESETUnderTlNEFigure2.2"TypicalPressureTransient d921e:1d/060269 2.4 APPENDIXGMAXIMUMliMITLYilNPMINLRCPflSEALMINIYlNLIYilTSETP">"RAN"~PDRVSKTPOlNT, l'SIGFigure2.3SetpointDetermination (MassInput)d$21e:1d/060289 2.5 044/WPM-1lfD<<y AppendixGMaximumLimit'NAXBINRCPflSealNinimvmLimitSETPOINTRANGEPSPORVSETPOINT~PSIGFigure2.4SetpointDetermination (HeatInput)SS21e:1d/0602S9 2.6 0l1t,'"+'A'b"1tf1~IttQJ"Pl-VIAI'I<~g t2.2MASSINPUTCONSIDERATIONS Foraparticular massinputtransient totheRCS,thereliefvalvewillbesignalled toopenataspecificpressuresetpoint.

However,asshowninFigure2.2,therewillbeapressureovershoot duringthedelaytimebeforethevalvestartstomoveandduringthetimethevalveismovingtothefullopenposition.

Thisovershoot isdependent onthedynamicsofthesystemandtheinputparameters (e.g.massflowrate),andresultsina.maximum system.pressuresomewhathigherthanthesetpressure.

Similarly, therewillbeanundershoot whilethevalveisrelieving, bothduetotheresetpressurebeingcbelowthesetpointandtothedelayinstrokingthevalveclosed.Themaximumandminimumpressures reachedinthetransient areafunctionoftheselectedsetpointandmustfallwithintheacceptable pressurerangeshowninFigure2.3.AnumberofmassinputcasesarerunatvariousLTOPSsetpoints

"'"--."'"<'.*'-"se'1'ecte'd'Co"bound*the expected'setpoint rangeandoverarangeofmassinjection'ates.

Fromtheseruns,alocusofthemaximumandminimumpressurevaluesisgenerated overtheexpectedsetpointrange,asshowninFigure2.3.~~~Theshadedarearepresents theacceptable rangefromwhichtoselectthesetpoint.

Themassinjection casesareconservatively analyzedatlowtemperature where"thebulkmodulusofthefluidisgreatest.

Theresulting overshoot isthereforworstcase,andevaluating massinjection eventsathigher,temperatures isnotrequired.

2.3HEATINPUT.CONSIDERATIONS Theheatinputcaseisanalyzedinaboutthesamewayasthemassinputcaseexceptthatthelocusoftransient pressurevaluesvs.selectedsetpoints aredetermined forseveralvaluesoftheinitialRCStemperature.

Thisheatinput,evaluation providesarangeofacceptable setpoints dependent onthereactorcoolanttemperature, whereasthemassinputcaseislimitedtothemostrestrictive lowtemperature conditions only.TheshadedareaonFigure2.4highlights theacceptable rangeforaheatinputtransient foraparticular initialreactorcoolanttemperature.

8921I:1d/060889 2.7 tJI

',2.4FINALSETPOINTSELECTION

.By,.superimposing theresultsoftheseveralmassinputandheatinputcasesevaluated (fromaseriesoffiguressuchas2.3and:2.4),

therangeofallow-ablesetpoints canbedetermined thatwillsatisfybothmassinputandheat'nputconsiderations.

Aspreviously stated,theseTection ofthepressuresetpoints forthePORVsisbasedontheuseofnominalupperandlowerlimits.Useofnominalvaluesisjustified basedontherecognized highdegreeofconservatism inherentinthe10CFR50AppendixGpressure-temperature limits.8921I:1d/060789 2.8

'0p~,I'.~II't>

~Pic.ALCE,\I/

4'3.0LTOPSSETPOINTANALYSESFORTHED.C.COOKUNIT2The.LTOPS setpointanalysispresented inthissectionwasdeveloped fortheAmericanElectricPowerCorporation sD.C.Cookunit2usingthealgorithm described intheprevioussection.Theanalysisevaluates theimpactofPORVopeningtimesupto10secondsonthevalueofthesetpointrequiredtomaintainoverpressures belowthe10CFR50AppendixGlimits.PORVclosuretimeisassumedtobe4secondsforallcases.Inaddition, thissectiondocuments thedevelopment ofthecorrelation benchmarking theresultsoftheanalysistothatofthealgorithm described inMestinghouse OwnersGroup(MOG)reportreferenced intheintroduction tothisreport.TheLTOPScurrently installed atCookUnit2featuresaconstantvaluesetpointprogram(i.e.aprogramindependent oftemperature) withan"-.'"enabl'e/disabl'e"reactor coolantsystemtemperature of152'F.-Theprogramsetpointiscurrently 435psigforbothPORV's.Theanalysisassumesoverpressurization transients resulting fromeithermassinjection orheatinputeventsunder4-loopwatersolidconditions, withthereplacement model51Fsteamgenerators.'he massinjection transient occursasaresultoftheoperation ofasinglecentrifugal chargingpumpconcurrent withaspuriouslossofletdown.Theallowable chargingconfiguration islimitedbytechnical specification toasingle.centrifugal=charging pumpin',operational modes5and6,;Thesafetyinjection pumpsarerequiredtoberackedoutinthese'odes.'he heatinjection eventresultsfromthestartofareactorcoolantpumpassumingthattheprimarywaterinthesteamgenerator is50'Fwarmerthanthewatercontained intherestofthereactorcoolantsystem.Thetemperature asymmetry candevelopduringacooldownmaneuverfollowing theshutoffofthereactorcoolantpumpsandcontinued coolingwiththeRHRsystem.NocreditistakenfortheRHRreliefvalvesforeitheroftheoverpressure scenarios.

Thesetpointselection isbasedonthemostrestrictive ofeitherthemassinjection orheatinputcases.Aconstraint

'required fortheanalysisistheassumption ofthefailureofoneofthePORV's.Thedesignbasisfortheoverpressure eventsrequirethat8921e:1d/06028S 3;1 0iz~'fI

eitherPORVprovideadequaterelieving capability intheeventofasingle~~~~valvefailure.CodeDescription Theevaluation ofthecoldoverpressure mitigation systemsetpoints isbasedon'ocalversionsoftheLOFTRANcode.Twoversionsofthecodewereutilized:

LOFT12,usedforthemassinputcalculations, collapses theseveralRCSloopsintoasingleloopmodel;and'OFT4, whichmodelseachloopexplicitly, fortheheatinputcalculation.

3.1OPERATIONAL LIMITSThepressure-temperature limitcurves(Appendix Gcurves)basedonrevision2'""of'USNRCRegulatory*Guide 1.99,havebeengenerated forreactorvesselexposures of12and32effective fullpoweryears(EFPY).Thesetpointevaluation isbasedonthesteady-state cooldownlimit,wherethetechnical

~~difference betweenasteady-state cooldownlimitandasteady"state heatuplimitistheassumedlocationoftheflaw;i.e.,insideoroutsideofthevessel.Thesteady-state limitprovidesthegreatestoperational marginandhasbeenacceptedbytheNRCwiththejustification that"mostpressuretransients haveoccurredduringisothermal metalconditions."

Thesteady-state limits"are showninFigure3.1and,indigitized form,inTable.3.1.Thecurvesalsoincludethe800psigPORVpipingloadlimit.Theanalysisassumesnominalvalues;i.e.,pressureinstrumentation uncertainties arenotincluded.

Thisisconsistent withstandardRestinghouse practice.

UseoftheAppendixGlimitswithoutinstrumentation uncertainty isjustified onthebasisofthelargeamountofconservatism (recognized bytheNRC)inherentinthedevelopment ofthelimits.The800psigpipipglimitresultsfromananalysisofwaterhammereffectsonreliefvalvepipihgforcertainclassesofrapidlyopeningreliefvalves(e.g.,Garrettvalves)underwatersolidconditions.

TheGarrettvalvesaresolenoidoperatedwitharapidlyincreasing flowvs.stempositioncurve.8921e:1d/060789 3.2 ltl'Io,tlr.~~'~1f'pl$$P P0RVP12EFPYIIIIIIIFigure3.1ReactorCoolantSystemSteady-State PressureTemperature Limitsat12and32EFPY89216:1d/072089 3.3 0'W'tÃ1tC&a'we

'44iIl~Wj4;,I1tgkb1tIl>%l<<~yp<<t TABLE3.1STEADY"STATE COOLDOMNPRESSURE/TEMPERATURE LIMITSRCSPressuresiRCSPressuresiRCSTemdeFRCS12EFPY32EFPYTemdeF12EFPY32EFPY85.090.095.0100.0105.0110;0115.0120.0125.0130,0'35.0140.0145.0150.0155.0160.0509.2513.3517.8522.6527.7'"5332'39.0545.4552.2559.6567.5576.1585.1594'.9605.5616.9490.2492.8495.7498.8502.1505.7509.6513.8518.2523.0528.2533.8539.6546.0552.9560:4165.0170.0175.0180.0185.0190.0a95.o200.0205.0210.0215.0220.0225.0230.0235.0240.0245.0629.1642.1656.3671.5687.7705.2724.1744.2766.0789.3814.5841.4870.49oa.6935.0970.81009.6568.3576.9586.1595.9606.6618.0630.4643.5657.7673.0689.3707..0726.0.746.3768.2791.7817.08921e:1d/0607883.4 I0,",L)~IL'LIIe1WIlJ'i'W+(Lf.I'IVL Whenacharacteristic curveofthistypeiscombined, withGarrett's typically rapidstroke'time (lessthantwoseconds).the"valvebecomeseffectively fullopenorfullclosedwithinafewtenthsofasecond,thussettingtheconditions forawaterhammer.'heflowthroughanairoperatedreliefvalve,whencomparedtosolenoidvalves,ismuchlesssensitive tostemposition.

Hhencombinedwiththerelatively slowopeningandclosingtimescharacteristic ofthesetypesof'valves,thewaterhammereffectswillbemuchreduced,ifnoteffectively eliminated.

Evaluation ofwaterhammerforcesonthepipingofairoperatedvalveshasnotbeenperformed byHestinghouse.

Thepracticehasbeentoassumetheconservative positionoftakingtheworstcaseresults(theGarrettanalysis) andapplyingthemtoallLTOPSsetpointevaluations, regardless ofthereliefvalveemployed.

3.2-PORVSTROKETIMEAsinstructed byAmericanElectricPowerCorporation, theLTOPSanalysisalso~~includesaparameter studyonvalveopeningtimeinordertodetermine therelationship betweenopeningtime.andLTOPSsetpoint.

Theparametric studywasperformed assuming6different valveopeningtimes,rangingfrom1.0sec.to10seconds.Thiswasconsidered abroadenoughrangetocoverallreasonable"opening timemeasurements;.

""""'""'""'The" PORVclo'singtimeselectedfor-theanalysiswassetat4.0seconds,independent oftheopeningtime.Theclosuretimeselection hasnoimpactontheoverpressure transient (anAppendixGconsideration),

butdoesimpacttheunderpressure transient (important fortheprotection ofthereactorcoolantpumpNo.1seal).Thecharacteristic ofthetransient issuchthatasclosuretimeincreases, theunderpressure becomesmoresevere.3.3PORVOPERATION Thedesignbasisforanoverpressure eventrequiresthateitherPORVprovideadequaterelieving capability intheeventofasinglevalvefailure.8921e:1d/0601893.5 L'I'~o4~ro

'herefore, thesetpointanalysisisbasedontheassumption ofsinglevalveoperation.

Thesetpointanalysisincludestheeffectoftimedelaysassociated withthetransmission ofthewideranger'eactorcoolantsystempressuresignal.Aconservative valueof0.95secondswasutilizedfortheanalysis.

Thebreakdown ofthetimedelayisasfollows:Pressuresensinglinetransport delay.,Pressuretransmitter delayElectronics delay...........'Solenoidactuation delayValveChamber(Pneumatic)',delay

....Total....0.15sec...0.25sec...0.10sec..0.10sec.,0.35sec...0.95secWiththeexception ofthepressuretransmitter delay,thefactorscomprising thetotal'elay timeareWestinghouse genericestimates forairoperatedpressurizer reliefvalves.'.

C.CookUnit2featurestwoFoxborowiderange(ModelN-EIIGH"HIM2-A) pressuretransmitters.

Westinghouse instrumentation grouphadnoinformation onFoxborotransmitters, sothedelaytimeof0.25secondswasobtaineddirectlyfromFoxboro's ProductInformation Group.Theflowcharacteristics (valveC(v).'vs.

valve'stroke)-

forthe-pressurizer.

poweroperatedreliefvalveswereobtainedfromAmericanElectricPowerCo.andareshownbyFigure3.2.ThepercentatfullflowC(v)corresponding toselectedpercentofvalvestrokevaluesislistedinTable3.2.3.4MASSINPUTCONSIDERATIONS Themassinjection transient isassumedtooccurasaresultoftheoperation ofasinglecentrifugal chargingpumpincombination withasuddenloss.ofletdown.Theallowable chargingconfiguration is-.limitedbytechnical specifications inoperational modes5and6,wheretheCookunitsLTOPSisenabled.Thechargingflow,assumingthatthenormalandalternate flowpaths,.are.bothopen,,asafunctionofreactorcoolantsystempressureisshowninFigure3.3.ThedateintabularformisgiveninTable3.3.BSZle:1d/0607BS3.6

('4~i0Ipf~+'+1~4~'I4CtfWI'i',IIIl'lp~IIC~

Iloaonoilon LinearhirOporotodReliefVolvoFullFlovC(v)~46Figure3.2Pressurizer PORYFlo~Characteristic Curve8921a:1d/060789 3.7 t1~*

TABLE3.2PRESSURIZER PORVCHARACTERISTICS~

PORVenin'AValve'AValve'AValve5Valve0.010.0.30.040.050.00.09.026.035.045.0'0.070.080.090.0100.056.066.077.088.0100.0PORVClosin5Valve'AValve%%dValve.5Valve0.010.020.030.040.0100.088.077.066.056.050.060.070.090.0100.045.035.026.09.0100.0"Basedonthecharacteristic curveshowninFigure3.2.8921e:1d/060789 3.8

,{;%VQ)'~W~r4'4fk'1P*t CharglnOuato~Slnl~CantrlfualggpChargingPunpFigure3.3MassInjection Flowvs.RCSPressure892)a:1d/0607893.9 841~I%OeEII TABLE3.3MAXIMUMCHARGINGFLOWATRCSPRESSURE~

RCSPress.+>~si~ChargingFlowmRCSPress.siChargingFlow'm400,500600700800900'='1000439.2429.7420.2410.7399.9386.2372.31100120013001400~1500160017001800358.3344.1329.8315.2300.5285.6268.9251.5"Basedonsinglecentrifugal chargingpumpoperation.

SS21e:1d/0607&9 3.10

~tt~,>>I~t~>>~I~

b'hemassinputcasewasconservatively analyzedatlowtemperature, 85'F,'herethe'pressure transient resulting fromamassinputshowsthegreatestovershoots andundershoots.

Noother,calculations wereperformed atdifferent temperatures, forthereasonthatthisistheworstcasesituation andtheD.C.CookUnit2LTOPSsetpointisindependent oftemperature.

Massinjection ratesrangingfrom100to600gpmwereselectedforthemassinputparameter studyportionoftheanalysis.

Thisrangewasbasedonanalysesperformed forunitssimilartoD.C.CookUnit2,andprovidesagooddefinition oftherelationship betweenmassinputandtheresulting pressuretransient.

TheresultsoftheLOFTRANrunsarepresented inFigures3.4through3.9forthebothoverpressure andunderpressure transients.

3.5.HEATINPUT.CONSIDERATIONS Theheatinputmechanism, fromthediscussion inSection1.3.2,isbasedona.singlereactorcoolantpumpstartupwithatemperature asymmetry existing~~betweentheprimarywaterheldupinthesteamgenerator tubesandthewater,intheremainder ofthereactorcoolantsystem.Themagnitude ofthe\asymmetry dependsonthepreviousplantoperation whichallowedtheasymmetry todevelop.Forthisstudy,itwasconsidered conservative toassumeamaximumasymmetry of50'Fasthedesignbasis,sincemuchhigherdifferences wouldbedifficult todevelop.TheheatinputcaseswereanalyzedatRCStemperatures of85'Fand150'F(steamgenerator temperatures of135'F'and 200'Frespectively).

Thecharacteristic behavioroftheoverpressure transient resulting fromaheatinputeventistobecomemoreseverewithincreasing RCStemperature.

Thisrequired.theadditional LOFTRANrunsatincreased temperatures inordertoprovideassurance thattheincr'ease inpressureovershoot withtemperature didnotexceedthatoftheAppendixGlimit,astheheatinjection eventsbegantodominate.;.

S921e:1d/060789 3.11 91Wq<c,pe~ver,~0>>4-v~*>C41p'ItV+I\e\fflhIIgl++lg)Ek4~we4J)

OIIODOAlo;CINeF00'0aI/1Figure3.4Overshoot andUndershoot dPVa1uesvs.MassInjection RateatPORVStrokeopentimeof1.0Sec.$921e:1d/OSOSS9 3.12 0tgVs~I'4"4')tAIll'I1g%*g)~IIIIfpI1gC O0Olostiel.~eec.0ailla'igure 3.5Overshoot andUndershoot hPYaluesvs.MassInject)on RateatPORYStrokeOpenTimeof2.0Sec.8921e:1d/080889 3.13 0~~':mViw'4'-eCea~-i,4~'gjjellSP4g,iIQC'P

!)IsPOaiuro~CQaC0aIllUIUIIWIIUUIWWllilWUlilllUIIIIIUllll Figure3.6Overshoot.and Undershoot hPValuesvs.MassInjection RateatPORVStrokeOpenTimeof4.0Sec.8921e:Ud/OBOS89 3.14 III7Pt@p4XItIl1'"9'hkCQ<t.sp,e,w."~'4+'f'!iI4'1 loC~0D0aQelraC0aFigure3.7Overshoot andUndershoot hPValuesvs.HassInjection RateatPORYStrokeOpenTimeof6.0Sec.8921e:id/080889 e4iIh1 I.VC10ORSULhO~0~C~t0aaDC0a.Figure3.8Overshoot andUndershoot hP,Valuesvs.MassInjection RateatPORVStrokeOpenTimeof8.0Sec.8921e:1d/060889 3.16 Cjl1ihw)s~c1Ipl/b\wt$-~"p'rI D0-POIIre~ee.C0aOeDC0aFigure3.9Overshoot andUndershoot hPYaluesvs.HassInjection RateatPORVStrokeOpenTime'of10.0Sec.892)e:1d/080889 3.11 plysI0P~~l%4'ligtl.+rpsinc'v"H

'.6SPECIFICATION FORMASSINPUTTRANSIENTS

~YtReactorCoolantSystemtemperature

=85'FReactorCoolantSstemVolume:RCSvolume=12,509cu.ft.fortheD.C.CookunitsInitialReactorCoolantSstemPressure:

TheinitialRCSpressurewasassumedtobe2QDpsilessthanthesetpoint....pressure.

Thisisconservative andassuresthatthetransient iswelldefinedbythetimethePORVsetpointisreached.Giventhisdefinition, theoverpressure isessentially insensitive totheinitialpressureselection.

ReactorCoolantReliefCaacit:Thetransient isanalyzedassumingthefailureofonePORV.PORYCharacteristics:

LTOPSSetpoints

=400,500,600,700psigPORVflowcharacteristics areshowninFigure3.2OpeningTime=1.0,2.0,4.0,6.0,8.0,10.0sec.Closingtime=4.0sec.C(v)=468921e:1d/060789 lflV~lU3(

4I,IMassIn'ection FlowCaabilit:MassinputRates=100,250,400,600gpmMaximumchargingflowcorresponding toLTOPSsetpointpressure.

(Ref.Table3.3)PressureSinalTransmission Characteristics:

TimedelaytoPORYstemmotion=0.95sec.3.7SPECIFICATION FORHEATINPUTTRANSIENTS

-"'"','".;,lS stem;Temeratures:

SG/RCStemperature difference

=50'FSteamgenerator (heatsource)temperature

=135'F,200'FReactorCoolantSstemVolume:Thesameasthatusedforthemassinjection cases.'"Initial.Reactor'Coolant SstemPressure:

TheinitialRCSpressure=200psilessthantheLTOPSsetpointpressureReactor-Coolant SstemReliefCapabilit:

Thesameasthatforthemassinjection casesPORVReliefCharacteristics:

Thesameas"thatforthemassinjection cases.89210:1d/060789 3.19 "1~AtkC 1SteamGenerator DesinCharacteristics:

"S/Gtubeheattransfer.surface.

area=,54,500sq.ft.S/Gtype=51F(D.C.CookUnit2replacement steamgenerator)

ReactorCoolantPuRCPtype=93APressureSinalTransmission Characteristics:

Thesameasthatforthemassinjection cases.3.8SETPOINTEVALUATION Theimpactofvariablemassinjection ratesandPORVopeningtimesonovershoot andundershoot valuesisprovidedbyTable3.4,Theinformation providedbythistableisbasedonthepressureovershoot/undershoot relationship withmassinjection rateshownincomposite Figures3.4through3.9.Theovershoot valuewasdetermined fromtheovershoot curvespresented inthesefiguresforthemaximummassinjection ratesconsistent withsinglecentrifugal chargingpumpinjection flow(fromFigure3.3,or.thetabulation

<<>>"".~shown in,Table3.3),for.

the.indicated.,PORV.

setpoint.,

Theundershoot valuewasconservatively estimated fromthemaximumdeltaPvaluebelowtheindicated setpoint.

Insomecases(PORVopeningtimesof1sec.and2sec.)theminimumdeltaPwasestimated byextrapolating theundershoot tozeromassinjection.

Thisprovidesabasisforestimating thesetpointrequirement forreactorcoolantnumber1sealprotection.

Theovershoot andundershoot pressures resulting fromtheheatinjection eventsare.showninTables3.5and3.6asfunctions ofsetpointpressureandPORVopeningtime.Thetablessummarize theresultsofLOFTRANrunsperformed forRCStemper'atures of85and150'F,respectively.

Theevaluation was8921e:1d/060789 3.20 0C, DDt4aass'4DtOTABLE3.4,IMaxOvershoot/Undershoot DeltaPValuesvsPORV0eninTimeDuetoMassInectionD.C.CookUnit2Overshoot/Undershoot Valuessivs.PORVeninTimesec*SetptPress.MassInj.st~Ratee400.0439.21.02.04.0Over.UnderOverUnderOver439.0231.0446.0232.0460.0Under282.06.08.010.0OverUnderOverUnderOverUnder473.0296.0487.0310.0499.0318.0500.0600.0700.0429.7420.2410.7538.0302.0542.0303.0555.0372.0566.0388,0578.0403.0588.0407.0635.0381.0641.0.388.0651.0460.0560.0482.0671.0492.0681.0493.0733.0465.0738.0479.0747.0547.0755.0576.0765.0577.0773.0591.0*PORVClosuretime=4.0sec.Notes:1.Hassinjection rateobtainedfromRCSpressurevs.singlepumpchargingflow.2.Overshoot obtainedfrommaxdeltaPovershoot Vs.massinjection flowcurve,3.Undershoot obtainedfrommaxdeltaPundershoot vs.massinjection

flow, 10'l~~IVE',"~u~J'I,~r>

tOaTABLE,3.5IMaxOvershoot/Undershoot DeltaPValuesvsPORVeninTimeDdetoHeatInectionD.C,CookUnit2Overshoot/Undershoot Valuessivs..PORVeninTimesec*Setpoint1.02.04.0.6;08.010.0vOver,UnderUnder330.0UnderOver323.0435.0OverUnderOverUnderOverOver,Under431.0427.0311.0525.0400.0420.0266.0423.0289.0dIOO.O418.0265.0528.0416.0531.0426.0500.0517.0329.0518.0335.0521.0372.0600.0617.0422.0.618.0426.0621.0463.0624.0496.0627.0513.0629.0523.0700,0716.0502.0717.0510.0720.0557.0723.0593.0726.0610.0728.0621.0"-ValveClosuretime=4.0sec.RCStemperature

=85.0'FS/Gtemperature

=135.0'F 40IIA/4j' TABLE3.6MaxOvershoot/Undershoot OeltaPValuesvsPORVeninTimeDueto}featInection0.C.CookUnit2Overshoot/Undershoot Valuessivs.PORVenintimesec*Setpoint1,02.04.06.08.010.0OverUnder400.0438.0278.0OverUnder445.0279.0OverUnderOver459.0295.0475.0Under311..0OverUnderOverUnder490.0311,05D5.0324.050D.O540.0338.0547.0342.0562.0381.0576.0395.0589.0407.0602.0408.0600.0-639,0419,0646.0433.0659.0468.0672.0487.0685.0493,0697.0495.0700;0"'739.'0512.0745.0516.0757.0563.0770.0579.0782.0581.0793.0585.0*ValveClosuretime~4.0sec.RCStemperature

=150.0'FS/Gtemperature 200,0'F lcnf'Iawn~>>i'd%Shg)*'eVq~-tR~i;e

~~~~~~~~~~~stoppedatthispoint(150'F)sinceitbecameevidentthatthemostlimitingtemperature withrespecttoAppendixGcriteriawasat85'Fandthatthemass...,..injection eventsaredominant.

Thedatafromthesetables(bothmassinjection andheatinjection) ispre-sentedinFigures3.10through:3.21, showingthemaximaandminimasystempressureasafunctionofsetpointpressureforthevalveopeningtimesselectedforthestudy.Figures3.10through3.15showthepressureextremaatanRCStemperature of85'F,andFigures3.16through3'.21showtheextrema-at150'F.Also.includedonthesefiguresistheAppendixGpressure.

limitat12and32EFPY,andtheminimumsystempressureforanRCPstart.TheAppendixGlimits(ref.Figure3.1)correspond totheRCStemperature assumedforthecalculation shownbythefigure.TheRCPseallimitwasselectedto'"...correspond,.to.the minimum.systempressurespecified byD.C.Cookforreactorcoolantfillandventoperations (325psig).Atothertimes,"thesystempressureisgovernedbytherequirement tomaintain200psidacrossthenumber,1RCPseal."Itisassumedthatthedifferential pressurerequirement acrossthesealplusthevolumecontroltankpressureandthestaticheadinthenumber1sealleakofflinewillbenomorethan325psig;thevaluespecified forfillandvent.Theintersection oftheselimits(Appendix GandRCPseal)withthemostlimitingofthemaximaandminima-curvesduetomassand/orheatinjection

,~=;.,'..events formsthe..basis.

fortheconstruction of..Figures 3.22and3.23.Thesefiguresshow,respectively, thedependency ofthemaximumallowedLTOPSsetpointonvalveopeningtimeforreactorvesselexposures of12EFPYand32EFPY.Theminimumsetpointlimit(RCPprotection) hasnotbeenshown,sincethe"whitespace"isgenerally notlargeenoughtomeetboththeRCPnumber1,seal'equirements and.theAppendixGlimit.8921e:1d/060669 3.24

."ling"C~'V5IVgr.VL=1A~CC4-Z4't 0$$$$$III3$$t$$IIE$$$$$$HeatIn)ection ExtreaaPressurixcr PORVOpeningTine1.1Sec.Pressurixor PORVClosingTine~4.6Sec.RCSTemperature

~BS.IOegFSteam6cnerator Tesperatur e~136.~OegFAppend6Lieat12EFPYAppend6Lieat32EFPYcRCPSealLimitprrFigure3.10$$RCSPressureExtremavs.SetpointPressureatPORVStrokeOpenTimeof1.0Sec.andRCSTemperature of85'F8921c:1d/060789 3$25 k;0F>>+g"IIIt0>>Ite4~'I tlassIntestate EetrenaHesttntaetten EeireaaPreseurliatPORVOpeningTice2.0Sec.PteaaurizerPORVClaalngTine~4.8Sec.RCSTenperature

>85.0DegFSteam6enerator Tenperatur

~~135.IDegFhppend6Lln~t12EFPYhppend6Llnat32EFPYRCPSealLimitFigure3e11RCSPressureExtremavs.SetpointPressureatPORVStrokeOPenTimeof2a0Sec.andRCSTemPerature of85'F$921e:1d/060789 3.26 lWI~0)g+C,g'Wg'I'gI"1i,li.s'III<<lkvg' ttassZntsctton Extras>toastIotasiionExtrsxaPressurixerPORVOpeningTineaa4.1Sec.Pressurizer PORVClosingTine4.bSec.RCSTenperatura~85.~DegFStean6enarator Tenperatur

~sa135.~DegFhppand6Linat12EFPYhppand6Lie"at32EFPYRCPSealLimitFigure3a12RCSPressureExtrema.vs.SetpointPressureatPORVx~StrokeOpenTimeof4.0Sec.andRCSTemperature of85'FBS21e:1d/0607BS 3.27 10gtt~'gtiJ'II0lt44I4'e+t.'

IlatsIntacttcn EntrantHeatIn>ection ExtrenaPteaeuriaer PORVOpen}ngTine6.8Sec.Preaauri?er PORVClosingTine~4.6Sec.RCSTenperature

~85.SOepFStean6eneratOrTeEEperatureEs135.1DegFhppend6'Linat12EFPYhppend6LiEEat.32EFPYIE~RCPSealLimitFigure,.3..13.,

RCS.Pressure Extrema,vs.

SetpointPressureatPORVStrokeOpenTimeof6.0Sec.andRCSTemperature of85'F8921e:1d/0607893a28 I4gttCJ+\g$,1NtVg'AD.

tlaaaIntaattnn EatraaaHastZnjaattnn EatraaaPressurizer PORVOpeningTine~B.bSeenPressurizer POAVClosingTine~4.8Sec.RCSTenperatut

~~86.bDegFStean6enerator Tenper~ture~l3S.~DegFi.tataa'lt>>an"'tahppend6Lieat12EFPYhppend6Linat32EFPYRCPSealLimit""""Figure-3.14" "RCS"Pressure

.Extremavs.SetpointPressureatPORVStrokeOpenTimeofSa0Sec.andRCSTemperature of85'FBB21a:1d/060789 3.29 4tr1'tJ,rk1,ji RaaeInleatlan EntrantHeatInfection ExtremePressurizer PORVOpeningTine~IB.BSacPresaurixerPORVCloaingTine~4.BSec.RCSTenperature

~85eBOegFSteanGenerator TeRRperatur e~135.BOegFhppend6Linat12EFPYhppend6Linat32EFPY,RCPSealLtnttFigure3.15RCSPressureExtremavs.SetpointPressureatPORVStrokeOpenTimeof10.0Sec.andRCSTemperature of85'FSS21e:1d/060789 3.30

>>,II~I~II>>>>'1yg>>p~ping'(>>>>'">>I>>.

nessinteotton EntreesHestIntenttonEatreaaPressurizer PORVOpeningTinean1.6Sec.PreaaurizerPORllClosingTine~4.8Sec.RCSTellperature

~150.8DegFStean6eneratorTemperature 288.0DegFAppend6Lieat12EFPYAppend6Lieat32EFPYRCPSealLimit'igure3.16RCSPressureExtremavs.SetpointPressureatPORVStrokeOpenTimeofla0Sec.andRCSTemperature of150F892le:1d/060789 3.31

~aarah~arKfa I!axeInteattnn ExtreneHeatIniaatinn ExiranePreaaurixet PORVOpeningTine~2.8Sec.PreasurizerPORVClosingTine~4.8SeenRCSTemperature

~150.8.8OegFStean6enerator Tenperatur e288.8.8OegFAppend6Llaat12EFPYAppend6Li~at32EFPYnCptealLtnti"Figure3.17RCSPressureExtremavs.SetpointPressureatPORVStrokeOpenTimeof2.0SectandRCSTemperature of150'F8921e:1d/060789 3.32 II0"\"\j4l lianaIntaattan EntranaHastIntanitan EntrantPressurizer VORVOpeningTine~4.8Sec.PrassurizerPORVClosingTine4.8Sec.RCSTenperature~158.8.8DegFStean6anarator Tenper~tur~~28B~8.8DegFhppend6Lillat12EFPYhppend6Linat32EFPYRCPSealLimitnPrr(Figure3.18RCSPressureExtremavs.SetpointPressureatPORVStrokeOpenTimeof4.0Sec.andRCSTemperature at1SO'F8921c:1d/0607893.33 0sl~(VIP*P4h~*t naaaIntention ExiraxeHantIntention ExtranaPreasurizerPORVOpeninpTine~6.8Sec.PreeeurizerPORVCloainpTine~4.SSec.RCSTemperature

~15I.IOepFhStean6enerator Temperature 2BB.BOepF~,ahAppend6Linat12EFPYAppend6Lieat32EFPYRCPSealLinttFigure3.19RCSPressureExtremavs.SetpointPressureatPORVStrokeOpenTimeof6;0Sec.andRCSTemperature of150'F8921e:1d/D60789 3.34 e~~

n'ianaIntaatten EntreatHeatInteetien EetlaaaPressurizer PORVOpeningTine~8.8Sec.PressurizerPORVClosingTime~4.8Sac.RCSTenparatur

~i150.8DegFStean6enersterTemperatua~288.~DegFAppend6Lieat12EFPYAppend6Lieat32EFPYRCPSealLimit"-Figure"3;20RCSPressure."Extrema vs.SetpointPressureatPORVStrokeOpenTimeof8.0Sec;andRCSTemperature of150'F8621e:1d/060789 3.35

~QQ.0I4ee1P' hansIniaoiion Extras'ast Inianiion ExisannPreaeuriverPORVOpeninpTine~1B.BSec.Pressurizer PORVCloainpTineaa4.BSecsRCSTemperature

~~l5I.~DepFStean6eneratorTenperatur

~2BB.BOepFAppend6Lieat12EFPYAppend6Lieat32EFPYRCpOaalLsnst~Figure3a21RCSPressureExtremavs.SetpointPressureatPORVStrokeOpenTimeof10.0Sec.andRCSTemperature of150'F892le:ld/060789 3.36 JI0IIr5'II1rw~~'Yv4Md6%

Notea.1)NoPreaau~Inatrunant Error2)SinglePORVOperation 5)PORVCloauraTtne~i.bSec.i)ReactorVeaaelExpoaur~~12EFPY)SB.BOepFRCSTeno.]BS.BOegFFigure3.22.PORYLTOPSetpointat12EFPYvs.ValveOpeningTimeB921e:1d/060/89 3.37

g~C Roice:1)NoPressureInstrument Error2)SinglePORVOperation 3)PORVCloaur~Tine~i.bSec.4)ReactorVesselExposure~32EFPY1a158.$OegFRCSTemp.~&S.ODegFFigure'3.23"PORVLTOPSetpointat32EFPYvs.ValveOpeningTime8921e:1d/060789 3.38

~%!la0'(I%IV14r>>

'.0CORRELATION'O MOGLTOPSSETPOINTMETHODOLOGY AspartoftheLTOPS'etpoint analysis"performed forD.C.CookUnit2,AmericanElectricPowerCorporation requested acorrelation thatbenchmarks theresultsoftheanalysistothatofthealgorithm described inthereport.preparedfortheMestinghouse OwnersGroup(acronymed MOG)onReactorCoolantSystemOver-pressurization byMestinghouse ElectricCorporation.

Thereasonfortherequestwastoprovideameanstodetermine theequivalent LOFTRANderivedsetpoints fromtheexecution ofarelatively simplealgorithm;.i.e.,'he MOGreport.Thecorrelation assumesamas'sinjection event,only.Thisisjustified onthefollowing bases:1)theLTOPS>>atD.C.Cookunit2featuresasetpoint'!'-~"::-~>'independent,"of".,temperature,')'he-most limiting'condition isatlowtemperature, and3)themassinjection eventdominates atlowtemperatures.,

Undertheseconditions, aswillbeshown,thecorrelation takestheformofaseriesofcurvesof"LOFTRAN" setpoints plottedagainstpressurizer PORVopeningtime,with;the"MOG"setpoints asaparametric.

4.1MOGMETHODOLOGY LTOPSSETPOINTS

,The,MOGmethodology, formass.injection events,determines the.resulting.

over-,pressurefroma4-factorformula;thederivation, ofwhich,isprovidedinthe","'"MOGreport.'referenced in"theintroduction.

tothisreport:DeltaP=DeltaP(Ref)~F(v)"F(s)~F(z)

Thefactorscomprising theformulaare-determined fromaseriesoflinearrela-tionships withknown(orassumed)plantparameters.

Forconvenience, theserelationships arereproduced herefromMOG:report,andareshownasFigures4.1through4.4.Fortheparameter studyperformed here,itisconvenient toexpressthesefiguresanalytically:

DeltaP(Ref)=~"(HassInjection Rate,ibm/sec)82B921e:1d/060ZSB 4.1

~\'11~aC'4k,W.',Stt>>'P"tt"q*."tt~~~r1~.~~~*ti4>>'I+

mme=.A..~RESSIIIthPREF~Refcftnee Overshoot FI6UREi.t.1Ik+-j-"~i"8:."...xtkssInputRate-lb/see"".FFigure4.1OeltaP(Ref)vs.MassInjection Rate8921e:1d/060789 4.2 0)ITr.tr,sI14~y~4>>~I<<gs M~~~~SSIn)ItFVRCSVolteFactorIF16UREi.2.2,'4:Al MM=--2~\~~~KK-~~~~~~~~~r~~~'I~t~'I~"I~OOO~I'il.:".Bi:.!ii V.TotalRCSVol~-ft'SOOOi:-Ii:.:.-'z-.:Figure4.2VolumeFactor,F(v),vs.RCSTotalVo1ume8921e:1d/06D789 4.3 0A1141~t~Clhtpd amassInputF>-kcllefHiveOpeningTksIeFactorFICHEa,2~~~I'~>>I'"If~~0~~~~~~::::LII~~~r>>~~I)I'I~~~~~I>><<~--ll~~%11>>as>>I>><<I<<y4I,>>>>1<<IL-~.L~~~~~~~~I<<I~~>>>>IMP~I-<<0<<nq<<1g>>~M">>~>>.I...~L1-i=~>>I=Z,kelfefValveOpeningTfaIe,secondsIiiiiI:'III0Figure4.3PORYOpeningTimeFactor,F(z),vs.ValveOpeningTime8921e:1d/0608894.4 0~w~C~at+I"'8IraM'"Ye1'fp~'4'.erEt)irlg~k~

~llnnnInnt=I:.:II::."

.:.FS-ReliefValveSetpo)ntfattnp'll."'I:-'-:.-,

~-.I::".~~.:i--'i:-:I.;::i:

~'.IWn.-J.-~~-w4~~>>I+fl+YII.~l>>nnY~>>Lfn+ng+}QIfI---->>'IY$Ii.~~~~M=~:.-~>>.II~A~d;)IIYNNW~nYn~\~"-:IL',Rel1afValveSetpoknt-palyI:.:.'.:.I:.:.:.:.

-:.I.':I-I.:i~::~I:.:.'::.:IIiFigure4.4LTOPSSetpointFactor,F(s),vs.LTOPSSetpoint8821~:1d/060889 4.5

~Cf?fJCWfCV~C??~C*'f*L~jfftf

'(v)=1.435-(0.725E"4)~(RCS Volume,cu.ft.)=0.53forCookunit2.(Cookunit2coldRCSvolume=12509.2cu.ft.)F(s)=1.810-(0.00135)~(PORV

Setpoint, psig)F(z)=0.200+(0.267)~(PORY OpeningTime,sec.)Theoverpressures resulting fromtheapplication ofthesefactorsaredocumented intabularformbelowandthroughpage4.9,fortheseveralPORV'opening-'-times'elected fortheanalysis.

,Asummaryoftheoverpressures isgivenonpage4.9.MassInectionOveressuresatPORVOneninTime=1.0sec.LTOPSSetointsi400500600700Inj.Mass(refTable3.3)(gpm)(ibm/sec.)

DeltaP(Ref)......,.4'(v)0~~~I-~~0.~~.i~F(s)o~~~~~~~~~F(z)oo~~~~~~o~DeltaP(psig).....

Overpressure (psig)439.260.9683.31..0.531.2700.46726.20426.2429.759.6481.51-.0.531.1350.46722.90522.9420.258.3279.700.531.0000.46719.70619.7410.757.0177.910.530.8650.46716.70716.78921e:1d/060889 4.6 S(E/E+EE)healEEtI~QE$IIII'E~r~liE5lgI

,MassIn'ectionOveroressures atPORVOoeninTime=2.0sec.LTOPSSetpointsi400500600700Inj.Mass(refTable(gpm)~~~~e~(ibm/sec.)

.OeltaP(Ref)....F(v)~~.~~~~~~F(s)e~~oo~~~F(x)o~~~~~~~-,6=,-.'Oe1.ta, P",.(psig),...,.Overpressure (psig)3.3)439.260.9683.310.531.2700.73441.20441.2429.759.6481.510.531.1350.734,'36.00536.0420.258.3279.700.531.0000,73431.00631.0410.757.0177.910.530.8650.73426.20726.2MassIn'ection Overoressures atPORVeninTime=4.0sec.LTOPSSet@ointsi400500600700Inj.Mass(refTable(gPlll)o~~~~~(ibm/sec.)

.DeltaP(Ref).'..F(V)~~~~~~~~F(s)o~~~~~e~F(Z)~~~~~~~~OeltaP(psig)Overpressure (psig).3.3)439.260.9683.310.531.2701.26871.10471.1429.759.6481.510.531.1351.268.62.20562.2420.258.3279.700.53;1.0001.26853.60-"653.6410.757,0177.910.530.8651.26845.30745.36921e:ld/060789 4.7 0t~~r'v.svv:~hELf~rII'r.)

.MassInectionOverressuresatPORVOneninTime=6.0sec.LTOPSSetoointsi400500600700Inj.Mass(refTable(gPlll)~~~~~,~(ibm/sec.)

DeltaP(Ref)F(v)J~~~~~~~f(s)J~~~~~~o.F(z)i~~~~~~~.~<<'Del,ta,.P.

(psig).........

Overpressure (psig).3.3)439.260.9683,31~~~~0J531.2701.802.......,..101.0501.0429.759.6481.510.531.1351.802,...,88.40 588.4420.258.3279.700.531.0001.80276.10676.1410.757.0177.910.530.8651.80264.40764.4MassInectionOveroressures atPORYeninTime=8.0sec.~~LTOPSSetoointsi400.500600700Inj.Mass(refTable(gpm)J~~~~~(ibm/sec.)

OeltaP(Ref)F(v)a~~~~~~~F(s)J~~~~~~~f(I)~~~~~~~~'eltaP(psig).Overpressure (psig).3.3)439.260.9683.310.531.2702.336131.0531.0'429.759.64.'1.510.531.1352.33611'4.5614.5420.258.3279.700.531.0002.33698.70698.7410.757.0177.910.530.8652.33683.40783.48921e:1d/060189 4.8

~~

MassInectionOveressuresatPORVeninTime=10.0sec.LTOPSSetoointsi400500500700Inj.Mass(refTable(gpm)0~~~~~(ibm/sec.)

DeltaP(Ref)F(Y)F(s)i~~~~o~~F(x)o~~~~~~~.',DeltaP,,(psig)

.Overpressure (psig).3.3)439.260.9683.310.531.2702.870160.9560.9429.759.6481.510.531.1352.870140.7640.7420.258.3279.700.531.0002.870121.2721.2410.757.0177.910.530.8652.870102.5802.5RCSOveroressure SummarLTOPSSetpointsiPORVOpeningTimesec400500600700..1.02.04.06.08.010.0426.2.....,522.9441.2536.0471.1S62.2501.0588.4531.0614.5'560'.9640.7619.7631.0653.6676.1698.7721.Z716.7726.2745.3764.4783.4805.5&921e:1d/0807&9 4.9 C.4~VI~4H.(0~W1~~riel4~-~eP~t4H1VM~4~I"htlt+40'I&t~'4+4%EsW10 ThesummaryisshowninFigure4.5,illustrating thehighdegreeoflinearity Iofthepeaksystempressureasafunctionofsetpointpressure.

Thepeaksystempressure, resulting fromimplementation oftheHOGmethodology, can,therefor beexpressed asalinearfunctionofsetpointpressure:

1)PeakSystemPress=A+B~(P)MOSandthepeaksystempressuremustbelessthantheAppendixGlimit.Thecoefficients oftheequationhavebeendetermined byperforming aleast-squaresfitonthepeakpressures (fromtheabovetable)asafunctionofsetpointpressure:

PORVOpeningTimesecCoefficients 1.02.04.06.08.010.038.8161.10105.35149.63194.13234.210.96830.95000.91400.87790.84140.81434.2LOFTRAN/MOG Correlation Thesystemoverpressures determined fromtheLOFTRANbasedanalysis're alsoquitelinear(reference Figures3.10through3.15),andcanbeexpressed aslinearfunctions ofsetpointpressureforeachofthePORVopeningtimes:2)PeakSystemPress=C:~D"(Pi)LOFT89216:1d/060189 4.10 0Qc+lCl~M4' 18.88.8-~PORVOpeningTine(sec)q6.82.81.8Figure4.5MaximumRCSOverpressrue Sasedon"MOG"Methodology vs.LTOPSSetpointPressure6921~:1d/060769 4.11

$f);>+0ra1L awiththepeaksystempressures requiredtobe'lessthantheAppendixGlimit.~~Aleast-squares fitofthedatain,Table3.4resultsin.thefollowing coefficients:

PORVOpeningTimesecCoefficients D1.02.04.06.08.010.047.8055.5076.9096.50115.40132.000.97900.97500.95700.94000.92700.9150Thepeaksystempressuredetermined byeithertheMOGalgorithm ortheLOFTRANbasedanalysesmustbelessthantheAppendixGlimit.Therefore, atthelimit,theoverpressure determined fromequation1mustbeequaltotheoverpressure determined fromequation2:+D~(PLoFT~

~A+B~~PMos)wIJL0FTA'-C'Mos8921e:)d/0608894.12 wPs0~LA%19UOk, Thecoefficients r'esulting fromthecombinedequations (1)and(2)areas.Cfollows:1Coefficients PORVOpeningTimesecA-C8'1.02.04.06.08.010.0"9.185.7429.7356.5284.93111.700.98910.97440.95510.93390.90770.8899Usingtheabovetableofcoefficients, theLOFTRANequivalent LTOPSsetpoints corresponding toaseriesofselectedHOGsetpoints istabulated below:SummarofLOFTRANEuivalentLTOPSSetooints siPORYOpening'ime:secLTOPSSetointsiSasedonMOGAlorithm3004005006007008001.02.04.06.08.010.0287.6298.1316.3336.7357.2378.7386.5395.5411.8430.1.448.0467.7485.4584.3492.9590.4507,3602.8523.5616.9-538.8-629.6556.7645.6683.2687.8698.3710.3...720.3734.6782.1785.3793.8803.6.,811.1.823.68921e:1d/OB07B9 4.13 V<f0~lAgO~t,"%4*k=I 4'hetabulation" isshowngraphically inFigure4.6,andplotstheLOFTRAN'derivedLTOPSsetpointasafunctionofPORVopeningtime;parametric withthetWOGLTOPSsetpoint.

Thisfigureisusedtotranslate theLTOPSsetpointderivedfromapplication oftheWOGmethodology totheLOFTRANequivalent value.Utilization ofthefigurerequiresthattheLTOPSsetpointfirstbedetermined usingtheWOGmethodology, AtthePORVopeningtimecorresponding tothatselectedfortheWOGcalculation, determine theLOFTRANanalysissetpointfromtheordinatebylinearlyinterpolating betweenthetwocurvesboundingtheWOGsetpoint.

4.3IMPACTOFSTEAMGENERATOR TUBEPLUGGINGBoththeLOFTRANandtheWOGbasedanalyseswereperformed assumingnotubes'plugged"in thesteamgenerators.

The-impact oftubepluggingisasmallreduction inRCSvolume;theconsequence, ofwhich,isslightlyhigherover-pressures asaresultofmassinjection events,'and reducedoverpressures fromheatinputevents.Theheatinputeventsarereducedinimportance becauseofthereducti'on inheattransfersurfaceareaofthesteamgenerators.

Theimportance oftubepluggingwithrespecttoitsimpactonLTOPSsetpoints isaccounted forbytheF(v)termintheWOGmethodology (reference Figure4.2),andisdirectlytranslatable totheLOFTRANbasedanalysisthroughthecorrelation developed inthischapter.~Asaworstcaseexample,reducingthenumberofsteamgenerator tubesby154overallfoursteamgenerators,

'resultsinareduction inRCScoldvolumeof492..6cu.ft.(basedonanaveragetubelengthof69.77ft.,atubeO.D.of0.875inches,andawallthickness of0.050inches).Thisrepresents afractional reduction ininitialRCSvolumeofabitlessthan4A(i.eee0.0394)..

Theimpactonoverpressure canbedetermined fromtheF(v)equationin:section4.1.Withouttubeplugging(RCS:volume

=12509.2cu.ft.),F(v)=0.53.'With15Kofthetubesplugged(RCS-volume

=12016.6cu.ft.),F(v)increases to0.56.Thisrepresents anincreaseinthedeltaoverpressore of1.068,almosta7%increase.

'9216:1d/060789 4.14 O~~

MOSLTOPSSetpnt(yahoo)Figure4.6LOFTRAN/HOG SetpointCorrelation vs.PORVOpeningTime89216:1d/060789 4.15 l~40Wkc4't\~4,,tt-4WL4J4+4I-4'PtP$l+~[h1'i')rI'A\I'4l0-

~hSECTICN4(KRATIN6INSTRUCTINS IIITAIDTlGIHl&SH93TI%

FiOW4'+lipAOuSWAH.uc:0c~

~uop~<<byBa"kCp~-o+s)falNORMA4MININNpNDMAXIMLMOPERATING VALUES4.1.1Pump1.IIo.ISea1ITEMUNITNORMALMINIMUMMAXIMUMNOTESPlowgpmSeeFigure4-00.25.01,2,3Temperature degreesF100-19060235Pressurepsig22503252485fvl$4iHIA4)4'1@Co't%

~rl%~hPpsi22172002470HOTOPERATIONAL RECOMMENOKO ALARMSETTINGSHIGHfLOW-5.0GPMLOWFLOW-.TGPMO3C7I4lIQg2.::SAFE'PERA TINGRANGK.',~7~20III0200400600RAAIA>0I."CIAl400IRAA1800200022002400I'"'502'IOOSgg.DlmlNrmllnlI~HIp,>@IllI!Ql.1$AOOOROIFIGURE4-0tlo.1SealPerformance Parameters 4-1Rev.1 NO-C0~5POl~.0

NoresDu'ringheatuporcooldown, vhenthesystemvacerpressureis1000'psigorbelow,leak~ffElowmaybeinsufficient tocaolthebearingandsealcompo-nents.Whencheleak-offflowisbelov1gpm,thesealbypassvalveshouldbe-opened.

ThispermitsalimiredflovtobypasstheNo.1sealthroughanon-ad)useable orificeblock(external tothepumpitself).2~Iftheleak-offflowislessthan0.2gpm,icisprobablechar.minorforeignmacterisrestricting cheElovacthesealfaceinlet.Thesealfacesactlikeafilter.Foreignparticles intheorderaf25-40micronscancollectbetweenthefacesandrestricr.

theflow.Increasing thesealdif-ferential pressure(hP)mayclearcheseal.Ificdoesnoc,decreasechesealdifferential pressureto100psiandturnchepumprocorbyhand.Donotstartthepumpmotorifthesealflowisbelovchespecified minimum.3~IfaslowincreaseincheNo.1sealleak-offElavisobserved, i.e.overaperiodofseveraLweeksormore,Wescinghouse shouldbenotifiedcoprovideguidance.

DuringthisperiodchepumpmaybeoperacedandtheNo.1sealLeak~ffvalveshouldbeLefr.open.Thesealleak-offElovshouldnotbepermitted toexceedchelimitsofthesafeoperating rangeofFigure4W.Iftheseconditions donocexist,theprocedures foremergency operation shownundertheNo.2sealshouldbefollowed.

4.,Thistemperature ismeasuredbyachermocouple ac,theoutletofcheNo.1seal.Themaximumvalueshownshouldnotbeexceededeitherinnormalserviceorduringaloss-of-injection condition.

Theminimumlooppressure(325psig)appliesonlyduringthefillingandventingoperation.

Theminimumlooppressureforsubsequent operations iscancrolled by>theminimum4PacrosscheNo.1seal(200psi).2.No.2Seal,MIHlt%Mf"AXINNNOTES;"FlowTemperature

%LetPressurgphdegreesFpsiN/A33..Negligible N/A15N/A75psi3073Flow12Temperature degreesFN/AN/Apsi2235N/Aif/A*NotesNormaloperation

-No.1sealoperacive.

2.TheHo.2seeltemperature willvaryviththeNo.1sealtemperacure andisnocconsidered i,nfozmntivc.

4-LaM(v.I

~~t~'

3.Established byprevailing systemconditions.

4;Emergency operation

-No.lsealinoperative, withaprimarypressuredropoccurring acrosstheNo.2seal.Thefollowing actionshouldbetaken:a.ClosetheNo.1leak-offvalvewithinfiveminutes.b.Prepareforpumpshutdown.

Thepumpmaybeoperatedforaperiodnottoexceedanadditional 30minutes.Duringthisperiod,thereactorpowershouldberampeddowntotheN-1allowable powerlevel,whereNisthenumberofoperating RCpumps.c.Securethepump.d.Donotrestartthepumpuntilthecauseofthesealmalfunction hasbeendetermined.

3.No.3SealPlowTemperature UNITcc/hrdegreesF100N/AMINIMlN.Negligible N/ANXINN200N/ApsiFlowTemperature gphdegreesF-N/AN/AN/AN/AN/Apsi15N/AN/A*Notes1.,Normal.operation

-No.1sealoperative.

2.TheNo.3sealtemperatures arenotconsidered informative.

3.Thesea1differential pressureLsestablished bytheheadtank.4.Emergency operation

-No.1seal,inoperative, withaprimarypressuredropoccurring acrosstheNo.2seal.Refertonote4ofparagraph 4.1.1.1.4.lnjectlon WaterITEMUNITMINIMLNNXIMLHNOTESPlow12Temperature PressuredegreesF130N/A601'50N/A4-lbRev.1

"~0's4~-qp)i<q~~~k>~t.pi~et~e~@ewa>~tWcI'

~<*Notes..1....The, normalflowdistribution is5gpm'intothesystemand3gpmforthesealsupply.2.Ifthein]ection

~aterisincreased to150'F,~thereactorcoolanttempera-tureshouldbead)ustedtoatemperature nottoexceed400'F.3.Infection waterpressureisad)ustedtoobtaintherequiredflow.5.ThermalBarrierCooiingWaterMINION/AXINGNOTESFlow403560Temperature PressuredegreesFpsi8015060N/A105200*Notes1.Watershallbesuppliedfromthenon-radioactive component coolingsystem.Pressureshallbeadequaretoensuretherequiredflow.6.BearingMaterITEMUN[TMININNTemperature degreesF160Ambient225*Note1.Refertoparagraph 4-5-1,items1and2(LossofIn]ection WaterandHighTemperature ofInjection Water).7.SealPurgeWaterTheNo.3sealisfittedwithaconnection forpurgewatertominimizethebuildupofboricacidcrystalsacthetopoftheseal.Ifpurgeflowisconsidered necessary, 2to4gphofcool,clean,deminerali-ed, non-borated watershouldbeinjected.

ThepurgewaterdrainsoutthroughthenormalNo.3sealleak-offline.Whenpurge~aterisused,theflowsofthetableinpara-graph4-1.1-3donotapply.8.AlarmSettings, 1Alarmsettingsshouldbesetinaccordance withthemaximumorminimumvaluesown.on"the preceding charrs.4-lcRev.1

'00 LICENSING REPORTFORSTORAGEDENSIFICATION OFD.C.COOKSPENTFUELPOOLINDIANAMICHIGANPOKERCOMPTE&byHoltecInternational

<<bLAEPSCContractNo.C-7926HoltecProject00480 I'IIII DOCUMENTNAME:HOLTECINTERNATIONAL REVIEWANDCERTIFICATION LOGLICENSING REPORTFORSTORAGEDENSIFICATION OFD.C.COOKSPENTFUELPOOLHOLTECDOCUMENTIAD.NO.HOLTECPROJECTNO.CUSTOMER/CLIENT:

HZ-90488AMERICANELECTRICPOWER(INDIANAMZCHZCANPOWERCO.)REVISIONBLOCKISSUENO.ORIGINALREVISION1REVISION2REVISION3REVISION4AUTHOR&DATE57mC'~g((q@

Cg~<>+resoAc~y9~8'tYHl5'sl9~REVIEWER&DATEQSiIarrvCOflr~Cs9/~t$9(lgg.lnfQ.A.MANAGER.&DATEgl~ClV+,5o(rgl.c>>1~~rc~..r'FirCMn.APPROVEDBY&DATEM~l~+c+Cc((9'lV4+ggCi0<REVISION5REVISION6Ylv@4Rid8So&~PPEIrb]~IC/g~~GO~'/NOTE:Signatures andprintednamesarerequiredinthereviewblock.MustbeProjectManagerorhisDesignee.

Thisdocumentconformstotherequirement ofthedesignspecification andtheapplicable sectionsofthegoverning codes.Thisdocumentbearstheinkstampoftheprofessional engineerwhoiscertifying thisdocument.

SEALrggs}ggPALSlHGHt",12G906ElJ>g"3PProesszonalEngineer I

SUMMARYOFREVISZONS Revision1containsthefollowing numberofpagesoftextincludintablesbutexcudinfiuresTitlePageReviewandCertification LogSummaryofRevisions PageTableofContentsListofFiguresSection1Section2Section3Section4Section5Section6Section7Section8.Section9Section10111438178(later)2348513(later)11Revision2containsthefollowing numberofpagesoftextincud'ntablesand'esTitlePageReviewandCertification LogSummaryofRevisions PageTableofContentsListofFiguresSection1Section2Section3Section4Section5Section6Section7Section8Section9Section101114381814NotincludedinRevision23378517NotincludedinRevision2NotincludedinRevision2 i)~

SUMMARYOFREVISIONS Revision3containsthefollowing numberofpagesoftextinclud'ntablesandfiuresTitlePageReviewandCertification LogSummaryofRevisions PageTableofContentsListofFiguresSection1Section2Section3Section4AppendixAtoSection4Section5Section6Section7Section8Section9Section10Sectionll11243919143493376517ll54Revision4containsthesamenumberofpagesasRevision3withtheseexcetions:ListofTables(addedtoRev.4):3SectionsrevisedinRev.4nowcontainthefollowing numberofpages:Section1Section2Section4Section5Section99183534llIndividual pagesrevisedandtransmitted inRevision4are:Pages3-1,3-3<3-4,6>>6,6-15,6-18,6-28,6-30,7-4,7-5,7-6,8,7and10-2.

SUMMARYOFREVISIONS HoltecReportHZ-90488Revision5Thefollowing isrevisedinRevision5:Pages4-8and4-9Section9,Appendix APagevofTableofContentsRevision6ThefollowinaesarerevisedinRevision6:ListofFiguresTableofContents(pagev)2-14-15,4-1652I53I55I56I58~59I510I512I515I516I517~518'-19,5-20,5-21,5-24through5-386-3,6-4,6-357-2,7-48-6,8-7,8-1310-411-3 4f~lI~~~~lI~t TABLEOFCONTENTS

1.0INTRODUCTION

2.0MODULEDATA2.1SynopsisofNewModules2.2MixedZoneTwoRegionStorage(MZTR)2.3MaterialConsiderations 2.3.1Introduction 2.3.2Structural Materials 2.3.3PoisonMaterial2.3.4Compatibility withCoolant2.4ExistingRackModulesandProposedReracking Operation

3.0 CONSTRUCTION

OFRACKMODULES3.1Fabrication Objective 3.2MixedZoneTwoRegionStorage3.3AnatomyofRackModules3.4Codes,Standards andPractices fortheD.C.CookSpentFuelPoolRacks3.5Materials ofConstruction 2-12-12-12-42-42-42-42-72~73-13-13-23-23-53-94.0CRITICALITY SAFETYANALYSES4.1DesignBasis4-14-14.2SummaryofCriticality Analyses4.2.1NormalOperating Conditions 4.2.2AbnormalandAccidentConditions 4-4444-64.3Reference FuelStorageCells4.3.1Reference FuelAssembly4.3.2HighDensityFuelStorageCells4-84-84-9

~~~f TABLEOFCONTENTS(continued) 4.4Analytical Methodology 4.4.1Reference DesignCalculations 4.4.2FuelBurnupCalculations andUncertainties 4.4.3EffectofAxialBurnupDistribution 4-104-104-124-134.5Criticality Analysesand'olerances 4.5.1NominalDesign4.5.2Uncertainties duetoManufacturing Tolerances 4.5.2.1BoronLoadingTolerances 4.5.2.2BoralWidthTolerance 4.5.2.3Tolerance inCellLatticeSpacing4.5.2.4Stainless SteelThickness Tolerances 4.5.2.5FuelEnrichment andDensityTolerances 4.5.3Water-gap SpacingBetweenModules4.5.4Eccentric FuelPositioning 4-154-154-154-154-164-164-164-164-174-174.6Abnormal4.6.14.6.24.6.34.6.4andAccidentConditions Temperature andWaterDensityEffectsDroppedFuelAssemblyLateralRackMovementAbnormalLocationofaFuelAssembly4-174-174-184-184-194.7ExistingSpentFuel4.8References 5.0THERMAL-HYDRAULIC CONSIDERATIONS 5.1Introduction 5.2SpentFuelCoolingSystemDescription 5.2.1SystemFunctions 5.2.2SystemDescription 5.2.3Performance Requirements 5.3DecayHeatLoadCalculations 4-194-215-15-25-25-35-45-4

~~~~lI TABLEOFCONTENTS(continued) 5.4Discharge Scenarios 5.5BulkPoolTemperatures 5.6LocalPoolWaterTemperature 5.6.1Basis5.6.2ModelDescription 5.7CladdingTemperature 5.8BlockedCellAnalysis5.9References forSection56.0RACKSTRUCTURAL CONSIDERATIONS 6.1Introduction 6.2AnalysisOutline6.3Artificial SlabMotions6.4OutlineofSingleRack3-DAnalysis6.5DynamicModelfortheSingleRackAnalysis6.5.1Assumptions 6.5.2ModelDescription 6.5.3FluidCoupling6.5.4Damping6.5.5Impact6.6AssemblyoftheDynamicModel6.7TimeIntegration oftheEquations ofMotion6.7.1TimeHistoryAnalysisUsingMulti-Degree ofFreedomRackModel~6.7.2Evaluation ofPotential forInter-Rack Impact.6.8Structural Acceptance Criteria6.9MaterialProperties 5-55-65-115-115-125-135-165-166-16-16-26-36-56<<76-96-116-126-136-136-146-176-176-196-196-21 c'l TABLEOFCONTENTS(continued) 6.10StressLimitsforVariousConditions 6.10.1NormalandUpsetConditions (LevelAorLevelB)LevelDServiceLimits6.11ResultsfortheAnalysisofSpentFuelRacksUsingaSingleRackModeland3-DSeismicMotion6.12ImpactAnalyses6.12.1ImpactLoadingbetweenFuelAssemblyandCellWall6.12.2ImpactsbetweenAdjacentRacks6.13WeldStresses6.13.1Baseplate toRackWeldsandCell-to-Cell Welds6.13.2HeatingofanIsolatedCell6.14WholePoolMulti-Rack Analysis6.14.1Multi-Rack Model6.14.2ResultsofMulti-Rack Analysis6.15BearingPadAnalysis6.16References forSection67.0ACCIDENTANALYSISANDMISCELLANEOUS STRUCTURAL EVALUATIONS 7.1Introduction 7.2Refueling Accidents 7.2.1DroppedFuelAssembly7.3LocalBucklingofFuelCellWalls7.4AnalysisofWeldingJointsinRackduetoIsolatedHotCell7.5CraneUpliftLoadof3000lbs.7.6References forSection76-226-226-256-256-286-286-286-316-296-306-306-326-346-366-377-17-17-17-17-27~37-47-4

TABLEOFCONTENTS8.0STATICANDDYNAMICANALYSESOFFUELPOOLSTRUCTURE 8.1Introduction 8.2GeneralFeaturesoftheModel8.3LoadingConditions 8.4ResultsofAnalyses8.5PoolLiner8.6Conclusions 8.7References forSection89.0RADIOLOGICAL EVALUATION 8-18-38-68-108-118-118-129-19.1FuelHandlingAccident9.1.1Assumptions andSourceTermCalculations 9.1-2Results9-19-19.2SolidRadwaste9.3GaseousReleases9.4Personnel Exposures 9.5Anticipated ExposureduringReracking 9.6References forSection910.0IN-SERVICE SURVEILLANCE PROGRAM10.1Purpose9-59-59-59-69-810-110-110.2Coupon10'.110.2.210.2.310.2.410.2.510.2.6Surveillance Description ofTestCouponsBenchmark DataCouponReference DataAccelerated Surveillance Post-Irradiation TestsAcceptance Criteria10-210-210-310-310-410-410-410.3References forSection1010-5 Ii1~~g~~~~

TABLEOFCONTENTS11.0COST/BENEFIT

ANALYSIS, 11.1Introduction 11.2ProjectCostAssessment 11.3ResourceCommitment 11.4Environment Assessment 5I LISTOFTABLESTable1.1.1Table1.1.,2Table1.1.3Table2.1.1Table2.1.2Table2.1.3Table2.3.1Table2.3.2Table2.3.3Table2.3.4Table4.1Table4.2Table4.3Table4.4Table4.5Table4.6Table5.4.1Table5.4.2Discharge ScheduleAvailable StorageintheDonaldC.CookPoolRackModuleData,ExistingandProposedRacksModuleDataCommonModuleDataModuleDataBoralExperience List(Domestic andForeign)1100AlloyAluminumPhysicalandMechanical Properties ChemicalComposition (byweight)-Aluminum(1100Alloy)BoronCarbideChemicalComposition, Weight%BoronCarbidePhysicalProperties SummaryofCriticality SafetyAnalysesNormalStorageConfigurations SummaryofCriticality SafetyAnalysesInterimCheckerboard LoadingReactivity EffectsofAbnormalandAccidentConditions DesignBasisFuelAssemblySpecifications Reactivity EffectsofManufacturing Tolerances EffectofTemperature andVoidonCalculated Reactivity ofStorageRackFuelSpecificPowerandPoolCapacityDataDataforScenarios 1through3 l~~~-ll LISTOFTABLES(continued)

Table5.4.3Table5.5.1DataforScenarios 1through3PoolBulkTemperature andHeatGeneration RateDataTable5.5.2Table5.6.1Table5.6.2Table5.7.1Table6.3.1Table6.5.1Table6.6.1Time-to-Boil forVariousDischarge Scenarios PeakingFactorDataDataforLocalTemperatures LocalandCladdingTemperature OutputDatafortheMaximumPoolWaterCondition (Case1)Correlation Coefficient DegreesofFreedomNumbering SystemforGapElementsandFrictionElementsTable6.6.2Table6.9.1Table6.11.1Table6.11.2Table6.14.1Table6.14.2Table6.14.3Table6.14.4Table6.14.5Table8.4.1TypicalInputDataforRackAnalyses(lb-inchunits)RackMaterialData(200'F)SupportMaterialData(200'F)StressFactorsandRack-to-Fuel ImpactLoadRackDisplacements andSupportLoadsRackNumbering andWeightInformation MaximumDisplacements fromWPMRRunMPlMaximumDisplacements fromWPMRRunMP2MaximumDisplacements fromWPMRRunMP3MaximumRackDisplacements andFootLoadSafetyFactorsforBendingofPoolStructure RegionsViL3.

I LISTOFTABLES(continued)

Inventories andConstants ofFissionProductRadionuclides Significant DataandAssumptions fortheEvaluation oftheFuelHandlingAccidentTypicalConcentrations ofRadionuclides intheSpentFuelPoolWaterPreliminary EstimateofPerson-Rem Exposures DuringReracking DonaldC.CookNuclearPlantWorstCaseSpentFuelInventory I

LISTOFFIGURESFigure2.l.1Figure3.3.1Figure3.3.2Figure3.3.3Figure3.3.4Figure3.3.5Figure4.1Figure4.2Figure4.3Figure4.4Figure4.5Figure4.6CookSpentFuelPoolLayout(upperboundcellcount3616cells)SeamWeldingPrecision FormedChannelsComposite BoxAssemblyArrayofCellsforNon-FluxTrapModulesAdjustable SupportLegElevation ViewofRackModuleNormalStoragePattern(MixedThreeZone)InterimStoragePattern(Checkerboard)

Acceptable BurnupDomaininRegions2&3FuelStorageCellCrossSectionKENOCalculational ModelEquivalent Enrichment forSpentFuelatVariousBurnupsforInitialEnrichment of4.95%Figure4.7Figure4.8Figure5.5.1Figure5.5.2Figure5.5.3Figure5.5.4Figure5.5.5Figure5.5.6Figure5.5.7EffectofWater-Gap SpacingBetweenModulesonSystemReactivity Acceptable BurnupDomaininRegions263ShowingExistingSpentFuelAssemblies

.PoolBulkTemperature ModelDonaldC.CookSFPNormalDischarge, OneCoolingTrain,CaselaDonaldC.CookSFPNormalDischarge, OneCoolingTrain,Case1bDonaldC.CookSFPNormalDischarge, TwoCoolingTrains,Case2DonaldC.CookSFPFullCoreOffloadTwoCoolingTrains,Case3DonaldC.CookSFPFullCoreOffloadOneCoolingTrain,Case4CookSFPLossofCoolingScenario, Casela Il FigureFigure5.6.25.6.3Figure6.2.1Figure6.3.1Figure6.3;2Figure6.3.3Figure5.5.8Figure5.5.9Figure5.5.10Figure5.5.11Figure5.6.1LISTOFFIGURES(continued)

CookSFPLossofCoolingScenario, Case1bCookSFPLossofCoolingScenario, Case2CookSFPLossofCoolingScenario, Case3CookSFPLossofCoolingScenario, Case4Idealization

'ofRackAssemblyThermalChimneyFlowModelConvection CurrentsinthePoolPictorial ViewofRackStructure DBE-N-SAcceleration TimeHistoryDBE-E-WAcceleration TimeHistoryDBE-VerticalAcceleration TimeHistoryLISTOFFIGURES(continued)

Figure6.3.4Figure6.3.5Figure6.3.6Figure6.3.7Figure6.3.8Figure6.3.9Figure6.3.10Figure6.3.11Figure6.3.12Horizontal DesignSpectrumandN-STimeHistorySpectrum(5%damping)Horizontal DesignSpectrumandE-WTimeHistorySpectrum(5%damping)VerticalDesignandTimeHistoryDerivedSpectra(5%damping)OBE-N-SAcceleration TimeHistoryOBE-E-WAcceleration TimeHistoryOBE-VerticalAcceleration TimeHistory'Horizontal DesignSpectrumandTimeHistoryDerivedN-SSpectrum(2%damping)Horizontal DesignSpectrumandE-WTimeHistoryDerivedSpectrum(2%damping)VerticalDesignandTimeHistoryDerivedSpectra(2%damping)

LISTOFFIGURES(continued)

Figure6.5.1Figure6.5.2Figure6.5.3Figure6.5.4Figure6.5.5Figure6.5.6Figure6.6.1Figure6.14.1Figure6.14.2Schematic ModelforDYNARACKRack-to-Rack ImpactSpringsImpactSpringArrangement atNodeiDegreesofFreedomModelling RackMotionRackDegreesofFreedomforX-ZPlaneBendingRackDegreesofFreedomforY-2PlaneBending2-DViewofRackModuleRackandFootPedestalNumbering forCookMulti-Rack ModelCookPoolMulti-Rack SeismicAnalysis, RunMP2Rack16toRack17SouthCornerDynamicGapatRackTopFigure6.14.3Figure6.14.4CookRackRackCookRackRackPoolMulti-Rack SeismicAnalysis, RunMP216toRack17SouthCornerDynamicGapatTopPoolMulti-Rack SeismicAnalysis, RunMP312toRack18WEstCornerDynamicGapatTopFigure6.14.5Figure7.3.1Figure7.4.1Figure8.2.1Figure8.2.2Figure8.2.3Figure8.3.1CookPoolMulti-Rack SeismicAnalysis, RunMP3Rack12toRack18EastCornerDynamicGapatRackTopLoadingonRackWallWeldedJointinRackIsometric ViewofCookSpentFuelPoolOverallFiniteModelofCookPoolTopViewOverallFiniteModelofCookPoolBottomViewPedestalLoadvs.Time I

1.0INTRODUCTION

DonaldC.Cookisatwinunitpressurized waternuclearpowerreactorinstallation ownedandoperated, byIndianaMichiganPowerCompany.DonaldC.Cookreceiveditsconstruction permitfromtheAECinMarch,1969,anditsoperating LicenseinOctober,1974forUnit1andDecember1977forUnit2.Thetworeactorswentintocommercial operation inAugust,1975(Unit1)andJuly,1978(Unit2),respectively.

TheDonaldC.Cookfuelstoragesystemismadeupofafuelpool58'-31/8"longx39'-19/16"widewithanintegralcasklaydownarea.Thepoolpresently contains1367spentfuelstorageassemblies and36miscellaneous hardwareitems.Thus,outofthetotalinstalled storagecapacityof2050storagecells,1403storagecellsarepresently occupied.

Sincethefullcorehas193fuelassemblies forbothDonaldC.Cookreactors, maintaining fullcoreoffloadcapability fromonereactorimpliesthat1857storagecells(2050minus193)areavailable fornormaloffloadstorage.Table1.1.1providesthedataonpreviousandprojected fuelassemblydischarge intheDonaldC.Cookspentfuelpool.Table1.1.2,constructed fromTable1.1.1data,indicates thatDonaldC.Cookwilllosefullcoredischarge capability (foronereactor)in1995.Thisprojected lossoffullcoredischarge capability promptedthepresentundertaking toincreasespentfuelstoragecapability intheDonaldC.Cookpool.

IIIl Thepurposeofthislicensing submittal istoreracktheDonaldC.Cookpoolandequipitwithnewpoisonedhighdensitystoragerackscontaining 3613storagecells.Thereracking alsoentailsrelocation ofthethimbleplugtool,spentfuelhandlingtool,RodClusterControlAssembly(RCCA)changetool,andBurnablePoisonRodAssembly(BPRA)toolbracketstotheSouthwalladjacenttothecaskpit.Twentythreefree-standing poisonedrackmodulespositioned withaprescribed andgeometrically controlled gapbetweenthemwillcontainatotalof3613storagecells(including 3trianglecellslocatedattheSW,NWandNEcornersofthepool).Outofthesecells,theperipheral cellslocatedineachrackmoduleareflux-trapcells*,andtheinterioronesareoftheso-called non-fluxtraptype.Thestoragecellssuitableforstoringfreshfuel(upto5%enrichment) areuniquelyidentified (seeSection4.0,Figures4.1and4.2),andaresurrounded bynon-fluxtrapcellswhichhaveaburnuprestriction onthefuelwhichtheycanstore.Consistent withtheconceptoftworegionstorage,theplacement offuelwithagivenburnupintheallowable locationisadministratively controlled.

Nocreditistakenforsolubleboroninnormalrefueling andfullcoreoffloadstorageconditions.

Afluxtrapconstruction impliesthatthereisawatergapbetweenadjacentstoragecellssuchthattheneutronsemanating fromafuelassemblyarethermalized beforereachinganadjacentfuelassembly.

l Itisnotedthat,theproposedreracking effortwillincreasethenumberoflicensedstoragelocations to3613and,.asindicated inTable1'.2,willextendthedateoflossoffullcoredischarge, capability throughtheyear2008.Table1.1~3presentskeycomparison dataforexistingandproposedrackmodulesforDonald'.Cook.Thenewspentfuelstorageracksarefree-standing andselfsupporting.

Theprincipal construction materials forthenewracksareSA240-Type 304stainless steelsheetandplatestock,andSA564-630 (precipitation hardenedstainless steel)fortheadjust-ablesupportspindles.

Theonlynon-stainless materialutilizedintherackistheneutronabsorbermaterialwhichisboroncarbideandaluminum-composite sandwichavailable underthepatentedproductname"Boral".Thenewracksaredesignedandanalyzedinaccordance withSectionIII,Division1,Subsection NFoftheASMEBoilerandPressureVessel(B&PV)Code.Thematerialprocurement,

analysis, andfabrication oftherackmodulesconformto10CFR50AppendixBrequirements.

ThisLicensing Reportdocuments.

thedesignandanalysesperformed todemonstrate thatthenewspentfuelrackssatisfyallgoverning requirements oftheapplicable codesandstandards, inparticular/

"OTPositionforReviewandAcceptance ofSpentFuelStorageandHandlingApplications",

USNRC(1978)and1979Addendumthereto.

IIN(l Thesafetyassessment oftheproposedrackmodulesinvolveddemonstration ofitsthermal-hydraulic, criticality andstructural adequacy.

Hydrothermal adequacyrequiresthatfuelcladdingwillnotfailduetoexcessive thermalstress,andthatthesteadystatepoolbulktemperature willremainwithinthelimitsprescribed forthespentfuelpooltosatisfythepoolstructural strengthconstraints.

Demonstration ofstructural adequacyprimarily involvesanalysisshowingthatthefree-standing rackmoduleswillnotimpact.witheachotherorwiththepoolwallsunderthepostulated DesignBasisEarthquake (DBE)andOperating BasisEarthquake (OBE)events,andthattheprimarystressesintherackmodulestructure willremainbelowtheASMEB&PVCodeallowables.

Thestructural qualification alsoincludesanalytical demonstration thatthesubcriticality ofthestoredfuelwillbemaintained underaccidentscenarios suchasfuelassemblydrop,accidental misplacement offueloutsidearack,etc.Thecriticality safetyanalysisshowsthattheneutronmultiplication factorforthestoredfuelarrayisboundedbytheUSNRClimitof0.95(OTPositionPaper)underassumptions of95%probability and95%confidence.

Consequences oftheinadvertent placement ofafuelassemblyarealsoevaluated aspartofthecriticality analysis.

Thecriticality analysisalsosetstherequirements onthelengthoftheB-10screenandthearealB-10density.ThisLicensing Reportcontainsdocumentation oftheanalysesperformed todemonstrate thelargemarginsofsafetywithrespecttoallUSNRCspecified criteria.

Thisreportalsocontainstheresultsoftheanalysisperformed todemonstrate theintegrity ofthefuelpoolreinforced concretestructure, andanappraisal of1-4 I

radiological considerations.

Acost/benefit anaysisdemonstrating reracking asthemostcosteffective approachtoincreasetheon-sitestoragecapacityoftheDonaldC.CookNuclearPlanthasalsobeenperformed andsynopsized inthisreport.Allcomputerprogramsutilizedinperforming theanalysesdocumented inthislicensing reportareidentified intheappropriate sections.

Allcomputercodesarebenchmarked andverifiedinaccordance withHoltecInternational's nuclearQualityProgrameTheanalysespresented hereinclearlydemonstrate thattherackmodulearrayspossesswidemarginsofsafetyfromallthreethermal-,hydraulic, criticality, andstructural

-vantagepoints.TheNoSignificant HazardConsideration evaluation submitted totheCommission alongwiththisLicensing Reportisbasedonthedescriptions andanalysessynopsized inthesubsequent sectionsofthisreport.1-5 IIIIIII TableDISCHARGE SCHEDULE~CelelA+2A3A1B**4A2B5A6A3B7A4B8ASB9A6B10A7B11A8B12A9B13A10B14A11B15A12B16A13BMonth/Year12/19764/19784/197910/19795/19805/19815/19817/198211/19827/19833/19844/19852/19866/19875/19883/19896/199010/199011/19912/19923/19936/19937/199410/199411/19954/19963/19978/19977/1998NumberofAssemblies 6564648065926464728092808880808077807680808080808080808080Cumulative Inventory InthePool651291932733384304945586307108028829701050113012101282136214381518159816781758183819181998207821582238*'A-**ReactorUnit1Reactor.Unit21>>6 Table1.1.1(continued)

DISCHARGE SCHEDULE~Cele17A*14B**18A15B19A16B20A17B21A18B22A19B23A20B24A21BMonth/~e12/19981/20014/20005/2001.8/20019/200212/20021/20046/20045/200510/20059/20062/20071/20087/20087/2009I80808080808080808080808080808080NumberofAssemblies D'schareCumulative Inventory nthePoo2318239824782558263827182798287829583038311831983278335834383518A-ReactorUnit1**B-ReactorUnit21-7 IIIIIII Table1.1.2AVAILABLE STORAGEINTHEDONALDCCOOKPOOLNUMBEROFSTORAGELOCATIONS AVAILABLE

~Cc1eMonth/YearWithPresentLicensedCapacity2050Locations AfterReracking 3616Locations 7B11A8B12A9B13A10B14A11B15A12B16A13B17A14B18A15B19A16B20A17B21A18B19B23A20B24A21B25A768688612532452.372292*6/199010/199011/19912/19923/19936/19937/19948/19977/199812/19981/20004/20005/20018/20019/200212/20021/20046/20045/20059/20062/20071/20087/20087/200911/200910/199421211/1995132**4/199652***3/199723342254217820982018193818581778169816181538145813781298121811381058978898818738658578418338*258178**9818***fromboth*Dateoflossoffullcoreoffloadcapability reactors.

- Dateoflossoffullcoreoffloadcapability foronereactor.***Dateoflossofnormaldischarge capability 1>>8 IIIIIII Table1.1.3RACKMODULEDATA'XISTING ANDPROPOSEDRACKSITEMNumberofcellsNumberofmodulesNeutronAbsorber(Nom.)cellpitch,inch(Nom.)cellopeningsize,inchEXISTINGRACKS205020Boral10.5"8.884+0'24PROPOSEDRACKS3616*23Boral897n8.75"+0.04Includethreetriangular cornerstoragecells.1-9 IIIIIIII 2.0MODULEDATA2.1SnosisofNewModulesTheDonaldC.Cookspentfuelpoolconsistsofa39'-19/16"x58'-31/8"rectangular pitwitha10'-4"x10'-6"spacedesignated forcaskhandlingoperations.

Thepoolisconnected

'tothefueltransfercanalthroughaweirgateontheWestwall.Thisgateisnormallyclosed.Atthepresenttime,theDonaldC.Cookpoolcontainsmediumdensityrackswitha10.5"nominalassemblycenter-to-center pitch.Thereisatotalof2050storagecellsinthepool.Therearetwosizesofmodules,10xl0and10xll.The10x10moduleweighs33,800lb.andthe10xllmoduleweighs37,200lb.Figure2.1.1showsaftertheproposedandtabulated incontaining atotalpitch.themodulelayoutfortheDonaldC.Cookpoolreracking campaign.

AsshowninFigure2.1.1Table2.1.1,therearetwenty-three racksof3613storagecellswitha8.97"nominalTheessential celldataforallstoragecellsisgiveninTable2.1.2.ThephysicalsizeandweightdataonthemodulesmaybefoundinTable2.l.3.Insummary,thepresentreracking application willincreasethelicensedstoragecapacityoftheDonaldC.Cookpoolfrom2050to3613cells.2~2MixedZoneThreeReionStoraeMZTRThehighdensityspentfuelstorageracksintheDonaldC.Cookpoolwillprovidestoragelocations forupto3613fuelassemblies andwillbedesignedtomaintainthestoredfuel,havinganinitialenrichment ofup=to5wt%U-235,inasafe,eoolable, andsubcritical configuration duringnormaldischarge andfullcoreoffloadstoragesandpostulated accidentconditions.

2-1 IIIII AllrackmodulesforDonaldC.Cookspentfuelpoolareoftheso-called"free-standing" typesuchthatthemodulesarenotattachedtothepoolfloornordotheyrequireanylateralbracesorrestraints.

Theserackmoduleswillbeplacedinthepoolintheirdesignated locations usingaspecifically designedliftingdevice,andthesupportlegsremotelyleveled(usingatelescopic removable handlingtool)byanoperatoronthefuelhandlingbridge.Thelevelingoperations aredonewhenthesupportlegsareliftedoffthefloor.Exceptforthecrane,noadditional liftingequipment isneededwhilelevelingisbeingperformed.

Asdescribed indetailinSection3,allmodulesintheDonaldC.Cookpoolareof"non-flux trap"construction.

However,themodulebaseplates extendoutby7/8"(nominal),

suchthatthenom'inalgapbetweentheadjacentwallsoftwoneighboring racksis2"(nom.).Thus,althoughthereisasinglescreenofneutronabsorberpanelbetweentwofuelassemblies storedinthesamerack,therearetwopoisonpanelswithawaterfluxtrap(2"wide)betweenthemforfuelassemblies locatedincellsintwofacingmodules.Outofthesefluxtraplocations, andperipheral celllocations (cellsadjacenttopoolwalls)acertainnumberofstoragecellsaredesignated forstoringfreshfuel.Inaddition, asdescribed inSection4,acertainnumberofinteriorcellsineachrackaredesignated forstoringfreshfuelof5%wt.U-235(max.)enrichment.

Inthismanner,asufficient numberoflocations withoutanyburnuprestriction (RegionIcells)areidentified toenableunrestricted fullcoreoffloadoftheDonaldC.Cookreactorinthespentfuelpool.Theseso-called RegionIcellsareidentified inSection4ofthisreport.Theremaining storagecellshaveenrichment/burnup restrictions.

Appropriate restrictions ontheenrichment/burnup ofthestoredfuelinRegionIIandRegionIXIcellsarepresented inSection4.2~2 IOlII Eachrackmoduleissupported byatleastfourlegswhichareremotelyadjustable.

Thus,therackscanbemadeverticalandthetopoftherackscaneasilybemadeco-planar witheachother.Therackmodulesupportlegsareengineered toaccommodate variations ofthepoolfloor.Thesupportlegsalsoprovideanunderrackplenum'fornaturalcirculation ofwaterthroughthestoragecells.Theplacement oftheracksinthespentfuelpoolhasbeendesignedtoprecludeanysupportlegsfrombeinglocatedoverexistingobstructions onthepoolfloor.TheDonaldC.Cookracksaresubjected tomandatedseismicloadingspertheplantUFSAR.TheDesignBasisEarthquake (DBE)andOperating BasisEarthquake (OBE)seismicresponsespectraareprovidedandsynthetic timehistories aregenerated.

Theseacceleration timehistories areappliedasinertialoads(seeSection6.3).Undertheseseismicevents,therackmoduleshavefourdesignated locations ofpotential impact:(i)(ii)(iii)(iv)SupportlegtobearingpadStoragecelltofuelassemblycontactsurfacesBaseplate edgesRacktopcornersThesupportlegtopoolslabbearingpadimpactwouldoccurwhenevertheracksupportfootliftsoffthepoolfloorduringaseismicevent.The"rattling" ofthefuelassemblies inthestoragecellisanaturalphenomenon associated withseismicconditions.

Thebaseplate andracktopcornersimpactswouldoccuriftherackmodulestendtoslideortilttowardseachotherduringthepostulated DBEorOBEseismicevents.Section6ofthisreportpresentstheanalysismethodology andresultsforallthreelocations ofimpact,andestablishes thestructural integrity oftheracksundertheloadcombinations specified forplantconditions requiredbytheNRC.2~3 rIl~i~III Abearingpad,madeofaustenitic stainless steel,isinterposed betweenthesupportfootandthelinersuchthattheloadstransmitted totheslabbytherackmoduleundersteadystateaswellasseismicconditions arediffusedintothepoolslab,andallowable localconcretesurfacepressures arenotexceeded.

Section8ofthisreportpresentsthedetailedpoolstructure analysis.

2'MaterialConsiderations 2.3.1Introduction SafestorageofnuclearfuelintheDonaldC.Cookspentfuelpoolrequiresthatthematerials utilizedinthefabrication ofracksbeofprovendurability andbecompatible withthepoolwaterenvironment.

Thissectionprovidesthenecessary information onthissubject.2.3.2Structural Materials Thefollowing structural materials areutilizedinthefabrication ofthespentfuelracks:a.ASMESA240-304 forallsheetmetalstock.b.c~d~Internally threadedsupportlegs:ASMESA240-304.

Externally threadedsupportspindle:ASMESA564-630 precipitation hardenedstainless steel.Weldmaterial-perthefollowing ASMEspecification:

SPA5.9ER308.2.3.3oisonMateriaInadditiontothestructural andnon-structural stainless

material, theracksemployBoral,apatentedproductofAARBrooksSPerkins,asthethermalneutronabsorbermaterial.

Abriefdescription ofBoral,anditsfuelpoolexperience listfollows.Boralisathermalneutronabsorbing materialcomposedofboroncarbideand1100alloyaluminum.

Boroncarbideisacompound2-4 II havingahighboroncontentinaphysically stableandchemicalinertform.The1100alloyaluminumisalight-weight metalwithhightensilestrengthwhichisprotected fromcorrosion byahighlyzesistant oxidefilm.Thetwomaterials, boroncarbideandaluminum, arechemically compatible andideallysuitedforlong-,termuseintheradiation, thermalandchemicalenvironment ofaspentfuelpool.Boral'suseinthespentfuelpoolastheneutronabsorbing materialcanbeattributed tothefollowing reasons:Thecontentandplacement ofboroncarbideprovidesaveryhighremovalcrosssectionforthermalneutrons.

(ii)Boroncarbide,intheformoffineparticles, ishomogenously dispersed throughout thecentrallayeroftheBoral.(iii)(iv)Theboroncarbideandaluminummaterials inBoraldonotdegradeasaresultoflong-term exposuretogammaradiation.

Thethermalneutronabsorbing centrallayerofBoraliscladwithpermanently bondedsurfacesofaluminum.

(v)Boralisstable,strong,durable,andcorrosion resistant.

Thepassivation processofBoralinanaqueousenvironment resultsinthegeneration ofhydrogengas.Ifthegeneration rateofhydrogenistoorapid,thenswellingofBoralmayoccur.Laboratory studiesbyBoral'ssupplierindicatethattherateofhydrogengeneration isastrongfunctionoftheso-called impurities in,thechemicalcomposition oftheboroncarbidepowder,namelysodiumhydroxide andboronoxide.AARBrooksPerkinshasinstituted astrictprogramofmonitoring ofthechemistry ofboroncarbideusedinthe,manufacturing ofBoraltoensurethatnoswellingofthepanelswilloccur.Furthermore, 2-5 II randomlyselectedcouponsofBoralpanelsfromproduction runsaresubjected toswellingtestcheckstoprecludeanypossibility ofswellingofBoral.Boralismanufactured byAARBrooks&Perkinsunderthecontrolandsurveillance ofacomputer-aided QualityAssurance/Quality ControlProgramthatconformstotherequirements of10CFR50AppendixB,"QualityAssurance CriteriaforNuclearPowerPlantsandFuelReprocessing Plants".Asindicated inTable2.3.1,BoralhasbeenlicensedbytheUSNRCforuseinnumerousBWRandPWRspentfuelstorageracksandhasbeenextensively usedinoverseasnuclearinstallations.

BoralMaterialCharacteristics Aluminum:

Aluminumisasilvery-white, ductilemetallicelementthatisabundantintheearth'scrust.The1100alloyaluminumisusedextensively inheatexchangers, pressureandstoragetanks,chemicalequipment, reflectors andsheet,metal'work.Ithashighresistance tocorrosion inindustrial andmarineatmospheres.

Aluminumhasatomicnumberof13,atomicweightof26.98,specificgravityof'.69andvalenceof3.Thephysical/

mechanical properties andchemicalcomposition ofthe1100alloyaluminumarelistedinTables2.3.2and2.3.3.Theexcellent corrosion resistance ofthe1100alloyaluminumisprovidedbytheprotective oxidefilmthatdevelopsonitssurfacefromexposuretotheatmosphere orwater.Thisfilmpreventsthelossofmetalfromgeneralcorrosion orpittingcorrosion andthefilmremainsstablebetweenapHrangeof4.5to8.5.2-6 II BoronCarbide:Theboroncarbidecontained inBoralisafinegranulated powderthatconformstoASTMC-750-80nucleargradeTypeIII'heparticles rangeinsizebetween60and200meshandthematerialconformstothechemicalcomposition andproperties listedinTable2.3.4.2.3.4ComatibilitwithCoolantAllmaterials usedintheconstruction oftheDonaldC.Cookrackshaveanestablished historyofin-poolusage.Theirphysical, chemicalandradiological compatibility withthepoolenvironment isanestablished factatthistime.AsnotedinTable2.3.1,Boralhasbeenusedinbothventedandunventedconfigurations infuelpoolswithequalsuccess.Consistent withtherecentpractice, theDonaldC-Cookrackconstruction allowsfullventingoftheBoralspace.Austenitic stainless steel(304)iswidelyusedinnuclearpowerplants.2.4ExistinRackModulesandProosedRerackin0erationTheDonaldC.Cookfuelpoolcurrently hasmediumdensityrackmodules'ontaining atotalof2050storagecellsintwentymodules.Atthetimeoftheproposedreracking operation, approximately 1678cells(between6/1993and7/1994)outof2050locations willbeoccupiedwithspentfuel.Thereissufficient numberofopen(unoccupied) cellsinthepooltopermitrelocation ofallfuelsuchthattheexistingmodulescanbeemptiedandremovedfromthepool,andnewmodulesinstalled inaprogrammed manner.Aremotelyengagable liftrig,whichisdesignedtomeetthecriteriaofNUREG-0612 "ControlofHeavyLoadsofNuclearPowerPlants",willbeusedtolifttheemptymodules.Auxiliary BuildingCraneswillbeusedforthispurpose.Amodulechange-out 2-7 IIIII schemeandprocedure willbedeveloped whichensuresthatallmodulesbeinghandledareemptywhenthemoduleismovingataheightwhichismorethan12"abovethepoolfloor.TheAuxiliary Buildinghastwooverheadcraneswhichrideonrailsthattraversetheentirefuelhandlingareaofthebuilding.

Eachcranehasamainhookratedat150tons.Thesehooksaresinglefailureproof(SFP)(upto60tons).Inadditionthereisanauxiliary hoistontheEastCraneratedat20tons.Pursuanttothedefense-in-depth approachofNUREG-0612, thefollowing additional measuresofsafetywillbeundertaken forthereracking operation.

(ii)(iii)Thecraneandhoistwillbegivenapreventive maintenance checkupandinspection within3monthsofthebeginning ofthereracking operation.

Thecranehookwillbeusedtoliftnomorethan50%ofitssinglefailureproofcapacityof60tonsatanytimeduringthereracking operation.

(Themaximumweightofanymoduleanditsassociatedhandlingtoolis24tons).Theoldfuelrackswillbeliftednomorethan6"abovethepoolfloorandheldinthatelevation forapproximately 10minutesbeforebeginning theverticallift.(iv)Therateofverticalliftwillnotexceed6'erminute.(v)(vi)(vii)(viii)Therateofhorizontal movementwillnotexceed6'erminute.Preliminary safeloadpathshavebeendeveloped.

The"old"or"new"rackswillnotbecarriedoveranyregionofthepoolcontaining fuel.Therackupendingorlayingdownwillbecarriedoutinanareawhichisnotoverlapping toanysafetyrelatedcomponent.

Allcrewmembersinvolvedinthereracking operation willbegiventrainingintheuseoftheliftingandupendingequipment.

Thetraining2-8 I

(ix)seminarwillutilizevideotaoes oftheactualliftingandupendingrigsontyoicalmodulestobeinstalled inthepoolsEverycrewmemberwillberequiredtopassawrittenexamination intheuseofliftingandupendingapparatus administered bytherackdesigner.

Referring toFigure2.1.1,itisnotedthatthefuelhandlingbridgecranecannotaccessstoragecellsfacingtheeastwallandseverallocations inthesouthwest corner.Therefore, itwillbenecessary toloadtheinaccessible cellswithfuelwhentherackisstaged'certaindistance(approximately 20inches)fromthepoolwall.Havingloadedthesecells,themodulewillbeliftedapproximately 4inchesabovethepoolliner,andlaterally transported toitsfinaldesignated locations.

Afuelshuffling andrackinstallation sequencehasbeendeveloped toensurethatallheavyloadhandlingcriteriaofNUREG-0612 aresatisfied.

Therackhandlingrigisdesignedwithconsideration oftherackmoduleweightalongwiththecontained fuelassemblymass.Thefuelracks'willbebroughtdirectlyintotheAuxiliary Buildingthroughtheaccessdoorwhichisatgroundlevel(609'levation).

Thisdirectaccesstothebuildinggreatlyfacilitates therackremovalandinstallation effort.The"old"rackswillbedecontaminated totheextentpractical on-siteandapprovedforshippingpertherequirements of10CFR71and49CFR171-178,behousedinshippingcontainers, andtransported toaprocessing facilityforvolumereduction.

Non-decontaminatable portionsoftherackswillbeshippedtoalicensedradioactive wasteburialsiteorreturnedtositeforstorageifdisposalaccessisunavailable.

Thevolumereduction isexpectedtoreducetheoverallvolumeoftherackstoabout1/10thoftheiroriginalvalue.Allphasesofthereracking activitywillbeconducted inaccordance withwrittenprocedures whichwillbereviewedandapprovedbyX6M.2-9 I

ModuleI.D.A**BCDEFGH*Total~nantit5442421123Table21.1MODULEDATAArrayCellSize13x1412x1413x1212xl213xll12xll12x1013x14-(8x2)TotalCellCountforthisModuleTe9106726242885722641201663616Non-rectangular module.**ThreeoftheAmoduleshaveonetrianglecelltoaccommodate poolcornercurvature.

2-10 IIII Table2.1.2COMMONMODULEDATAStoragecellinsidedimension:

8.75"+0.04"Storagecellheight(abovethebaseplate):

168+1/16"Baseplate thickness:

Supportlegheight:Supportlegtype:Numberofsupportlegs:Remoteliftingandhandlingprovision:

Poisonmaterial:

Poisonlength:Poisonwidth:Cell'Pitch:0.75"(nominal) 5.25"(nominal)

Remotelyadjustable legs4(minimum)

YesBoral144"7.5"8.97"(nominal) 2-11 Table2.1.3MODULEDATADimensions (inch)*ModuleI.D.ABCDEFGHEast-West 117-3/16108-1/8117-3/16108-1/8117-3/16108-1/8108-1/8117-3/16North-South 126-3/16126-3/16108-1/8108-1/899-1/1699-1/1690-1/8126-3/16ShippingWeight~kis25.723.722.520.920.819.317'23.9*Alldimensions areboundingrectangular envelopes roundedtothenearestonesixteenth ofaninch.2-12 III Table2.3.1BORALEXPERIENCE LIST(Domestic andForeign)Pressurized.

WaterReactorsPlantUtilityVentedConstruc-tionMfg.YearBellefont 1,2DonaldC.Cook1,2IndianPoint3MaineYankeeSalem1,2SeabrookSequoyah1,2YankeeRoweZion1,2Byron1,2Braidwood 1,2YankeeRoweThreeMileIslandITennessee ValleyAuthority Indiana&MichiganElectricNYPowerAuthority MaineYankeeAtomicPowerPublicServiceElec&GasNewHampshire YankeeTennessee ValleyAuthority YankeeAtomicPowerCommonwealth EdisonCo.Commonwealth EdisonCo.Commonwealth EdisonCo.YankeeAtomicElectricGPUNuclearNoNoYesYesNoNoNo198119791987197719801979Yes1990Yes1964/1983 Yes1980Yes1988Yes1988Yes1988BoilingWaterReactorsBrownsFerry1,2,3Brunswick 1,2ClintonCooperDresden2,3DuaneArnoldJ.A.Fitzpatrick E.I.Hatch1,2HopeCreekHumboldtBayLaCrosseLimerick1,2Monticello Peachbottom 2,3Perry,1,2PilgrimShorehamSusquehanna 1,2VermontYankeeHopeCreekTennessee ValleyAuthority CarolinaPower&LightIllinoisPowerNebraskaPublicPowerCommonwealth EdisonCo.IowaElec.Light&PowerNYPowerAuthority GeorgiaPowerPublicServiceElec&GasPacificGas&ElectricDairyland PowerPhiladelphia ElectricNorthernStatesPowerPhiladelphia ElectricCleveland Elec.Illuminating BostonEdisonLongIslandLightingPennsylvania Power&LightVermontYankeeAtomicPowerPublicServiceElec&GasYesYesYesYesYesNoNoYesYesYesYesNoYesNoNoNoYesNoYesYes198019811981197919811979197819811985198619761980197819801979197819791978/1986 19892-13 IIIIIII Table2.3.1(continued)

ForeignInstallations UsingBoralFrance12PHRPlantsSouthAfricaKoeberg1,2Switzerland Electricite deFranceESCOMBeznau1,2GosgenNordostschweizerische Kraftwerke AGKernkraftwerk Gosgen-Daniken AGTaiWBIlChin-Shan 1,2Kuosheng1,2TaiwanPowerCompanyTaiwanPowerCompany2-14 IIIIIIIII Table2.3.21100ALLOYALUMINUMPHYSICALANDMECHANICAL PROPERTIES DensityMeltingRangeThermalConductivity (77deg.F)Coef.ofThermalExpansion (68-212deg.F)Specificheat(221deg.F)ModulusofElasticity TensileStrength(75deg.F)YieldStrength(75deg.F)Elongation (75deg.F)Hardness(Brinell)

Annealing Temperature 0.098lb/cu.in.2.713gm/cc1190-1215 deg.F643-657deg.C128BTU/hr/sq ft/deg.F/ft0.53cal/sec/sq cm/deg.C/cm13.1x10/deg.F23.6x10/deg.C0.22BTU/lb/deg.

F0.23cal/gm/deg'.

C10xl06psi13,000psiannealed18,000psiasrolled5,000psiannealed17,000psiasrolled35-45%annealed9-20%asrolled23annealed32asrolled650deg.F343deg.C2-15 IIIIIII Table2.3.3CHEMICALCOMPOSITION (byweight.)-ALUMINUM(1100Alloy)99.00%min.1.00%max.0.05-0.20%

max..05%max..10%max..15%max.AluminumSiliconeandIronCopperManganese Zincotherseach2-16 IIIIIII Table2.3.4BORONCARBIDECHEMICALCOMPOSITION WeihtTotalboronBisotopiccontentinnaturalboronBoricoxideIronTotalboronplustotalcarbon70.0min.18.03.0max.2.0max.94.0min.BORONCARBIDEPHYSICALPROPERTIES ChemicalformulaBoroncontent(weight)Carboncontent(weight)CrystalStructure DensityMeltingPointBoilingPointMicroscopic thermal-neutroncross-section B4C78.28%21.72%rombohedral 2.51gm./cc-0.0907 lb/cu.in.2450C(4442F)3500C(6332F)600barn2-17 IIIIt:IIII l.eI~1Wa'eos+a~:~I'I~~~~~0~~~'

III

3.0 CONSTRUCTION

OFRACKMODULESTheobjectof'thissectionistoprovideadescription ofrackmoduleconstruction fortheDonaldC.Cookspentfuelpooltoenableanindependent appraisal oftheadequacyofthedesign.Similarrackstructure designshaverecentlybeenusedinpreviouslicensing effortsforKuoshengUnits1&2(TaiwanPowerCompany);

J.A.FitzPatrick (NewYorkPowerAuthority);

IndianPoint2(Consolidated EdisonCompanyofNewYork,Inc.);ThreeMileIslandUnit1(GPUNuclear);

andHopeCreek1(PublicServiceElectricGasCompany).

Alistofapplicable codesandstandards isalsopresented.

3.1Fabrication Ob'ectiveTherequirements inmanufacturing thehighdensitystorageracksfortheDonaldC.Cookfuelpoolmaybestatedinfourinterrelated points:-(1)Therackmodulewillbefabricated insuchamannerthatthereisnoweldsplatteronthestoragecellsurfaceswhichwouldcomeincontactwiththefuelassembly.

(2)Thestoragelocations willbeconstructed sothatredundant flowpathsforthecoolantareavailable.

(3)(4)Thefabrication processinvolvesoperational sequences whichpermitimmediate verificationbytheinspection staff.Thestoragecellsareconnected toeachotherbyaustenitic stainless steelcornerweldswhichleadstoahoneycomb latticeconstruction.

Theextentofweldingisselectedto"detune"theracksfromtheseismicinputmotionoftheOperating BasisEarthquake (OBE)andDesignBasisEarthquake (DBE).3-1 II 3.2MixedZoneTwoReionStoraeAllrackmodulesdesignedandfabricated fortheDonaldC.Cookspentfuelpoolareoftheso-called "non-flux trap"type.Znthenon-fluxtrapmodules,asinglescreenofthepoisonpanelisinterposed betweentwofuelassemblies.

ThepoisonmaterialutilizedinthisprojectisBoral,whichdoesnotrequirelateralsupporttopreventslumpingduetotheinherentstiffness.

However,accuratedimensional controlofthepoisonlocationisessential fornuclearcriticality andthermal-hydraulic.

considerations.

Thedesignandfabrication approachto,realizethisobjective ispresented inthenextsub-section.

3.3AnatomofRackModulesAsstatedearlier,thestoragecelll'ocations haveasinglepoisonpanelbetweenadjacentaustenitic stainless steelsurfaces.

Thesignificant components oftherackmoduleare:(1)thestorageboxsubassembly (2)thebaseplate, (3)thethermalneutronabsorbermaterial, (4)pictureframesheathing, and(5)supportlegs.Therackmodulemanufacturing beginswithfabrication ofthebox.The"boxes"arefabricated fromtwoprecision formedchannelsbyseamweldinginamachineequippedwith.copperchillbarsandpneumatic clampstominimizedistortion duetoweldingheatinput.Figure3.3.1showsthebox.Theminimumweldpenetration willbe80%ofthe-boxmetalgagewhichis0.075"(14gage).Theboxesaremanufactured to8.75"X.D.(nominalinsidedimension).

Thedesignobjective callsforinstalling Boralwithminimalsurfaceloading.Thisisaccomplished bydieforminga"pictureframesheathing" asshowninFigure3-2 I4II 3.3.2.Thissheathing is0.035"thickandismadetoprecisedimensions suchthattheoffsetis.010"to.005"greaterthanthepoisonmaterialthickness.

AsshowninFigure3.3.1,eachboxhasfourlateral1"diameterholespunchednearitsbottomedgetoprovideauxiliary flowholes.Theedgesofthesheathing andtheboxareweldedtogethertoformasmoothedge.Thebox,withintegrally connected sheathing, isreferredtoasthe"composite box".The"composite boxes"arearrangedinacheckerboard arraytoformanassemblage ofstoragecelllocations (Figure3.3.3).The'nter-box weldingandpitchadjustment areaccomplished bysmalllongitudinal connectors.

Furtherdetailsaregivenlaterinthissection.Thisassemblage ofboxassemblies isweldededge-to-edge asshowninFigure3.3.3,resulting inahoneycomb structure withaxial,flexuralandtorsional rigiditydepending ontheextentofintercell weldingprovided.

ZtcanbeseenfromFigure3.3.3thattheedgesofeachinteriorboxareconnected tothecontiguous boxesresulting inawelldefinedpathtoresistshear.hbpl'horizontal surfaceforsupporting thefuelassemblies.

Thebaseplate isattachedtothecellassemblage byfilletwelds.Thebaseplate ineachstoragecellhasa5"diameterflowhole.Thebaseplate is3/4"thicktowithstand accidentfuelassemblydroploadspostulated anddiscussed inSection7ofthisreport.(3)Thethermalneutronabsorbermaterial:

Asmentioned inthepreceding section,Boralisusedasthethermalneutronabsorbermaterial.

(4)PictureFrameSheathin:Asdescribed earlier,thesheathing servesasthelocatorandretainerofthepoisonmaterial.

Figure3.3.2showsaschematic ofthesheathing.

3~3 IlII Thepoisonmaterialisplacedinthecustomized flatdepression regionofthesheathing, whichisnextlaidonasideofthe"box".Theprecision oftheshapeofthesheathing obtainedbydieformingguarantees that.thepoisonsheetinstalled initwillnotbesubjecttosurfacecompression.

Theflangesofthesheathing (onallfoursides)areattachedtotheboxusingskipwelds.Thesheathing servestolocateandpositionthepoisonsheetaccurately, andtoprecludeitsmovementunderseismicconditions.

SuortLes:Allsupportlegsaretheadjustable type(Figure3.3.4).Thetopportionismadeofaustenitic steelmaterial.

ThebottompartismadeofSA564-630 stainless steeltoavoidgallingproblems.

Eachsupportlegisequippedwithareadilyaccessible sockettoenableremotelevelingoftherackafteritsplacement inthepool.Lateralholesinthesupportlegprovidetherequisite coolantflowpath.Anelevation cross-section oftherackmoduleshowninFigure3.3.5showstwoboxcells,andadeveloped cellinelevation.

TheBoralpanelsandtheirlocationarealsoindicated inthisfigure.Theboralpanelsarepositioned suchthattheentireenrichedfu'elportionofthefuelassemblyisenveloped bythethermalneutronabsorbermaterial.

Thejointbetweenthecomposite boxarraysandthebaseplate ismadebysinglefilletweldswhichprovideaminimumof7"ofconnectivity betweeneachcellwallandthebaseplate surface.AsshowninFigure3.3.4,thesupportlegisgussetedtoprovideanincreased sectionforloadtransferbetweenthesupportlegsandthecellularstructure abovethebaseplate.

Useofthegussetsalsominimizes heatinputinduceddistortions ofthesupport/baseplate contactregions3-4 III 3.4CodesStandards andPractices fortheDonaldC.CookSentFuelPoolRacksThefabrication oftherackmodulesfortheDonaldC.Cookspentfuelpoolisperformed underastrictqualityassurance systemsuitableformanufacturing andcomplying withtheprovisions of10CFR50AppendixB.Thefollowing codes,standards andpractices willbeusedasapplicable forthedesign,construction, andassemblyofthespentfuelstorageracks.Additional specificreferences relatedtodetailedanalysesaregivenineachsection.a~CodesandStandards forDesinandTestin(1)AZSCManualofSteelConstruction, 8thEdition,1980.(2)ANSIN210-1976, "DesignObjectives forLightWaterReactorSpentFuelStorageFacilities atNuclearPowerStations".

(3)AmericanSocietyofMechanical Engineers (ASME),BoilerandPressureVesselCode,SectionIII/Subsection NF,1989.(4)ASNT-TC-1A, June,1980AmericanSocietyforNondestructive Testing(Recommended PracticeforPersonnel Qualifications).

(5)ASMESectionV-Nondestructive Examination (6)ASMESectionZX-WeldingandBrazingQualifications (7)BuildingCodeRequirements forReinforced

Concrete, ACI318-89/ACI318R-89.

3-5 IIOtII (8)CodeRequirements forNuclearSafetyRelatedConcreteStructures, ACI349-85andCommentary ACI349R-85(9)Reinforced ConcreteDesignforThermalEffectsonNuclearPowerPlantStructures, ACI349.1R-80 (10)ACIDetailing Manual-1980(11)ASMENQA-2,Part2.7"QualityAssurance Requirements ofComputerSoftwareforNuclearFacilityApplications (draft).(12)ANSI/ASME, Qualification andDutiesofPersonnel EngagedinASMEBoilerandPressureVesselCodeSectionIII,Div.1,Certifying Activities, N626-3-1977.Mate'aCodes(1)AmericanSocietyforTestingandMaterials (ASTM)Standards

-A-240.(2)AmericanSocietyofMechanical Engineers (ASME),BoilerandPressureVesselCode,SectionII-PartsAandC,1989.ASMEBoilerandPressureVesselCode,SectionIX-WeldingandBrazingQualifications (1986)orlatexissueacceptedbyUSNRC.ualitAssurance CealinessPacka'nShiReceivinStoraeandHandlinReuirements (1)ANSIN45.2.2-Packaging,

Shipping, Receiving, StorageandHandlingofItemsforNuclearPowerPlants.(2)ANSI45.2.1-CleaningofFluidSystemsandAssociated Components duringConstruction PhaseofNuclearPowerPlants."3-6 IIIII (3)ASMEBoilerandPressureVessel,SectionV,Nondestructive Examination, 1983Edition,including SummerandWinterAddenda,1983.(4)ANSI-N16.1-75NuclearCriticality SafetyOperations withFissionable Materials OutsideReactors.

(5)ANSI-N16.9-75Validation ofCalculation MethodsforNuclearCriticality Safety.(6)ANSI-N45.2.11, 1974QualityAssurance Requirements fortheDesignofNuclearPowerPlants.(7)ANSI14.6-1978, "SpecialLiftingDevicesforShippingContainers weighing10',000lbs.ormoreforNuclearMaterials".

(8)ANSIN45.2',Qualification ofInspection andTestingPersonnel.

(9)ANSIN45.2.8,Installation, Inspection.

(10)ANSIN45.2.9,Records.(ll)ANSIN45.2..10, Definitions.

(12)ANSIN45~212,QAAudits.(13)ANSIN45.2.13, Procurement.

(14)ANSI45.2.23,QAAuditPersonnel.

OtherReferences (Inthereferences below,RGisNRCRegulatory Guide)(1)RG1.13-SpentFuelStorageFacilityDesignBasis,Rev.2(proposed).

(2)RG1.123-(endorses ANSIN45.2.13)

QualityAssurance Requirements forControlofProcurement ofItemsandServicesforNuclearPowerPlants.(3)RG1.124-ServiceLimitsandLoadingCombinations forClass1LinearTypeComponent

Supports, Rev.1.3-7 III (4)RG1.25-Assumptions UsedforEvaluating thePotential Radiological Consequences ofaFuelHandlingAccidentintheFuelHandlingand"StorageFacilityofBoilingandPressurized WaterReactors.

(5)RG1.28-(endorses ANSIN45.2)-QualityAssurance ProgramRequirements, June'972.

(6)RG1.29-SeismicDesignClassification, Rev.3.(7)RG1.31-ControlofFerriteContentinStainless SteelWeldMetal,'ev.

3.(8)RG1.38-(endorses ANSIN45.2.2)QualityAssurance Requirements forPackaging,

Shipping, Receiving, StorageandHandlingofItemsforWater-Cooled NuclearPowerPlants,March,1973.(9)RG1.44-ControloftheUseofSensitized Stainless Steel.(10)RG.1.58-(endorses ANSIN45.2.2)Qualification ofNuclearPowerPlantInspection, Examination, andTestingPersonnel, Rev.1,September, 1980.(ll)RG1.64-(endorses ANSIN45..2.11)

QualityAssurance Requirements fortheDesignofNuclearPowerPlants,October,1973.(12)RG1.71-WelderQualifications forAreasofLimitedAccessibility.

(13)RG1'4-(endorses ANSIN45.2.10)

QualityAssurance TermsandDefinitions,

February, 1974.(14)RG1.85-Materials CodeCaseAcceptability ASMESectionIII,Division1.(15)RG1.88-(endorses ANSIN45.2.9)Collection, StorageandMaintenance ofNuclearPowerPlantQualityAssurance Records,Rev.2,October,1976.(16)RG1.'92-Combining ModalResponses andSpatialComponents inSeismicResponseAnalysis.

3-8 IIIIII (17).RG3.41-Validation ofCalculation MethodsforNuclearCriticality Safety.(18)GeneralDesignCriteriaforNuclearPowerPlants,CodeofFederalRegulations, Title10,Part50,AppendixA(GDCNos.1,2,61,62,and63).(19)NUREG-0800, StandardReviewPlan,Sections3.2.1,313.F1(3/3(38'(20)"OTPositionforReviewandAcceptance ofSpentFuelStorageandHandlingApplications,"

datedApril14,1978,andthemodifications tothisdocumentofJanuary18,1979.(Note:OTstandsforOfficeofTechnology).

(21)NUREG-0612, "ControlofHeavyLoadsatNuclearPowerPlants".(22)Regulatory Guide8.8,"Znformation RelativetoEnsuringthatOccupational Radiation ExposureatNuclearPowerPlantswillbeasLowasReasonably Achievable (ALtGQ.).

(23)10CFR50AppendixB,QualityAssurance CriteriaforNuclearPowerPlantsandFuelReprocessing Plants(24)10CFR21-Reporting ofDefectsandNon-Compliance 3'Materials ofConstruct'on

.StorageCell:Baseplate:

SupportLeg(female):

SupportLeg(male):Poison:ASMESA240-304 ASMESA240-304 ASMESA240-304 Ferriticstainless steel(anti-gallingmaterial)

ASMESA564-630Boral3-9 IIII Lateralflowholes'.75"WeldSeam.075"Figure3.3.1SEAMWELDINGPRECISION FORMEDCHANNELS3-10 IlI Sheathing Figure3.3.2COMPOSITE BOXASSEMBLY Ie~II Figure3.3.3ARRAYOFCELLSFORNON-FLUXTRAPMODULES3-12 IIII Baseplate GussetFigure3.3.4ADJUSTABLE SUPPORTIEG3-13 III BoxCellsCellPitchDeveloped

)cellBoralpanelSheathing Baseplate OneInchLateralFlowHole(Typical)

Figure3.3.5ELEVATION VIENOFRACKNODULE3-14 IIIlI

4.0 CRITICALITY

SAFETYANALYSES4.1DesiBasisThehighdensityspentfuelstorageracksforDonaldC.cookNuclearPlantaredesignedtoassurethattheeffective neutronmultiplication factor(k~ff)isequaltoorlessthan0.95withtheracksfullyloadedwithfuelofthehighestanticipated reactivity, andfloodedwithunborated wateratthetemperature withintheoperating rangecorresponding tothehighestreactivity.

Themaximumcalculated reactivity includesamarginforuncertainty inreactivity calculations including mechanical tolerances.

Alluncertainties arestatistically

combined, suchthatthefinalk,<<willbeequaltoorlessthan0.95witha954probability ata954confidence level.Applicable codes,standards, andregulations orpertinent sectionsthereof,includethefollowing:

oGeneralDesignCriteria62,Prevention ofCriticality inFuelStorageandHandling.

oUSNRCStandardReviewPlan,NUREG-0800, Section9.1.2,SpentFuelStorage,Rev.3-July1981oUSNRCletterofApril14,1978,toallPowerReactorLicensees

-OTPositionforReviewandAcceptance ofSpentFuelStorageandHandlingApplications, including modification letterdatedJanuary18,1979.USNRCRegulatory Guide1.13,SpentFuelStorageFacilityDesignBasis,Rev.2(proposed),

December1981.ANSIANS-8.17-1984, Criticality SafetyCriteriafortheHandling, StorageandTransportation ofLWRFuelOutsideReactors.

4-1 III Toassurethetruereactivity willalwaysbelessthanthecalculated reactivity, thefollowing conservative assumptions weremade:Moderator isassumedtobeunborated wateratatemperature withintheoperating rangethatresultsinthehighestreactivity (determined tobe204C).Theeffective multiplication factorofaninfiniteradialarrayoffuelassemblies wasused(seesection4.4.1)exceptfortheboundarystoragecellswhereleakageisinherent.

Neutronabsorption inminorstructural membersisneglected, i.e.,spacergridsareanalytically replacedbywater.'IiThedesignbasisfuelassemblyisa15x15(Standard)

Westinghouse containing UO>atamaximuminitialenrichment of4.95+0.05wt%U-235byweight.Forfuelassemblies withnaturalUO)blanketsg theenrichment isthatofthecentralenrichedzone.Calculations confirmed thatthisreference designfuelassemblywasthemost.reactiveoftheassemblytypesexpectedtobestoredintheracks.Threeseparatestorageregionsareprovidedinthespentfuelstoragepool,withindependent criteriadefiningthehighest.potential reactivity ineachofthetworegions's follows:Region1isdesignedtoaccommodate newfuelwithamaximumenrichment of4.95+0.05wt%U-235,orspentfuelregardless ofthedischarge fuelburnup.Region2isdesignedtoaccommodate fuelof4.954initialenrichment burnedtoatleast50,000MWD/MtU(assembly average),

orfuelofotherenrichments withaburnupyieldinganequivalent reactivity.

Region3isdesignedtoaccommodate fuelof4.954initialenrichment burnedtoatleast38,000MWD/MtU(assembly average),

orfuelofotherenrichments withaburnupyieldinganequivalent reactivity.

4-2 IIIII Thewaterinthespentfuelstoragepoolnormallycontainssolubleboronwhichwouldresultinlargesubcriticality marginsunderactualoperating conditions.

However,theNRCguidelines, basedupontheaccidentcondition inwhichallsolublepoisonisassumedtohavebeenlost,specifythatthelimitingkgffof0.9Sfornormalstoragebeevaluated intheabsenceofsolubleboron.Thedoublecontingency principle ofANSIN-16.1-1975 andoftheApril1978NRCletterallowscreditforsolubleboronunderotherabnormaloraccidentconditions sinceonlyasingleindependent accidentneedbeconsidered atonetime.Consecgxences ofabnormalandaccidentconditions havealsobeenevaluated, where"abnormal" referstoconditions whichmayreasonably beexpectedtooccurduringthelifetimeoftheplantand"accident" referstoconditions whicharenotexpectedtooccurbutnevertheless mustbeprot'ected against.4-3 lIII 4.24.2.1SummarofCriticalit AnalsesNormal0eratinConditions ThedesignbasislayoutofstoragecellsforthethreeregionsisshowninFigure4.1.Xnthisconfiguration, thefreshfuelcells(Region1)arelocatedalternately alongtherackperiphery (whereneutronleakagereducesreactivity) oralongtheboundarybetweentwostoragemodules(wherethewatergapprovidesaflux-trap whichreducesreactivity).

HighburnupfuelinRegion2affordsalow-reactivity barrierbetweenfreshfuelassemblies andRegion3fuelofintermediate burnup.Thereareatthepresenttime,anadequatenumberofspentfuelassemblies tonearlyfilland"blockoff"theRegion2barrierlocations (seeSection4.7).Thus,theadministrative controlsrequiredarecomparable toaconventional two-region storagerackdesign.Priortoapproaching thereactorend-of-life, notallstoragecellsareneededforspentfuel.Therefore, analternative configuration maybeusedinwhichtheinternalcellsareloadedinacheckerboard patternoffreshfuel(orfuelofanyburnup)with'mptycells,asindicated inFigure4.2.Thisconfiguration isintendedprimarily tofacilitate afullcoreunloadwhenneeded,priortothetimetheracksarebeginning tofillup.Figure4.3definetheacceptable burnupdomainsandillustrates thelimitingburnupforfuelofvariousinitialenrichments forbothRegion2(uppercurve)orRegion3(lowercurve),bothofwhichassumethatthefreshfuel(Region1)isenrichedto4.954U-235.Criticality analysesshowthatthemostreactiveconfiguration occursalongtheboundarybetweenmoduleswiththereactivity of4-4 4$1I Itheedgeconfiguration beingslightlylower.Theboundingcriticality analysesaresummarized inTable4.1forthedesignbasisstoragecondition (whichassumesthesingleaccidentcondition ofthelossofallsolubleboron)andinTable4.2fortheinterimcheckerboard loadingarrangement.

Thecalculated maximumreactivity of0.940(sameforboththenormalstoragecondition andtheinterimcheckerboard arrangement) iswithintheregulatory limitofak,<<of0.95.Thismaximumreactivity

.includescalculational uncertainties andmanufacturing tolerances (954probability atthe954confidence level),anallowance foruncertainty indepletion calculations andtheevaluated effectoftheaxialdistribution inburnup.Freshfueloflessthan4.954enrichment wouldresultinlowerreactivities.

Ascoolingtimeincreases inlong-term storage,decay'ofPu-241resultsinacontinuous decreaseinreactivity, whichprovidesanincreasing subcriticality marginwithtime.Nocreditistakenforthisdecreaseinreactivity otherthantoindicateconservatism inthecalculations.

Theburnupcriteriaidentified above(Figure4-3)foracceptable storageinRegion2andRegion3canbeimplemented inappropriate administrative procedures toassureverifiedburnupasspecified intheproposedRegulatory Guide1.13,Revision2.Administrative procedures willalsobeemployedtoconfirmandassurethepresenceofsolublepoisoninthepoolwaterduringfuelhandlingoperations, asafurthermarginofsafetyandasaprecaution intheeventoffuelmisplacement duringfuelhandlingoperations.

Thethickbase-plate ontherackmodulesextendbeyondthestoragecellsandprovideassurance thatthenecessary water-gap betweenmodulesismaintained.

4-5

~I~l~~l Forconvenience, theminimum(limiting) burnupdatainFigure4.3forunrestricted storagemaybedescribed asafunctionoftheinitialenrichment, E,inweightpercentU-235byfittedpolynomial expressions asfollows;ForReion2StoraeMinimumBurnupinMWD/MTU22'70+22I220E2I260E+149ForReion3StoraeMinimumBurnupinMWD/MTU26,745+18,746E-1,631E+98.4E4.2.2AbnormalandAccidentConditions Althoughcreditforthesolublepoisonnormallypresentinthespentfuelpoolwaterispermitted underabnormaloraccidentconditions, mostabnormaloraccidentconditions willnotresultinexceeding thelimitingreactivity (k,<<of0.95)evenintheabsenceofsolublepoison.Theeffectsonreactivity ofcredibleabnormalandaccidentconditions arediscussed inSection4.7andsummarized inTable4.3.Oftheseabnormaloraccidentconditions, onlyonehasthepotential foramorethannegligible positivereactivity effect.4-6

~tl~~~~~~(I~

Theinadvertent misplacement ofafreshfuelassemblyhasthepotential forexceeding thelimitingreactivity, shouldtherebeaconcurrent andindependent accidentcondition resulting inthelossofallsolublepoison.Administrative procedures toassurethepresenceofsolublepoisonduringfuelhandlingoperations willprecludethepossibility ofthesimultaneous occurrence ofthetwoindependent accidentconditions.

Thelargestreactivity increase(+0.065Sk)wouldoccurifanewfuelassemblyof4.954enrichment weretobepositioned inaRegion2locationwiththeremainder oftherackfullyloadedwithfuelofthehighestpermissible reactivity.

Underthisaccidentcondition, creditforthepresenceofsolublepoisonispermitted byNRCguidelines, andcalculations indicatethat550ppmsolubleboronwouldbeadecpxate toreducethek,<<tothecalculated k,<<(0.940)andapproximately 450ppmwouldbesufficient toassurethatthelimitingkoffof0.95isnotexceeded.

Doublecontingency principle ofANSIN16.1-1975, asspecified intheApril14,1978NRCletter(Section1.2)andimpliedintheproposedrevisiontoReg.Guide1.13(Section1.4,AppendixA).4-7 Il~~~~Ii~~

4'4.3.1Reference FuelStoraeCellsReference FuelAssemblThedesignbasisfuelassembly, described inFigure4.4,isa15x15arrayoffuelrodswith21rodsreplacedby20controlrodguidetubesand1instrument thimble.Table4.4summarizes thefuelassemblydesignspecifications andtheexpectedrangeofsignificant manufacturing tolerances.

Asshownbelow,initialcellcalculations withCASMO-3indicated thattheW15x15fuelexhibited aslightlyhigherreactivity inthestoragerackcellthaneithertheW17x17standardoroptimized (OFA)fuelortheANFfuelassemblydesigns.FuelteW15x15W15x15Enrichment:

2.52.5Burnup~D/DKU010Cell~k~1.02610.9210W17x17OFAW17x17OFAW17x17StndW17x17StndANF15x15ANF17x17W15x15W15x152.52.52.52.52.52.54.954.95010010000401.02050.91441.02170.91881.01481.01261.19410.9204W17xW17xW17xANF15ANF1717OFA17OFA17Stndx15x174.954.954.954.954.950400001.19330.91491.18801.18571.1883Highestvalues4-8

~~l~

Baseduponthecalculations listedabove,theWestinghouse 15x15roddesignwasusedasthebasisforthecriticality calculations.

4.3.2HihDensitFuelStoraeCellsThenominalspentfuelstoragecellusedforthecriticality analysesoftheDonaldC.CookspentfuelstoragecellsisshowninFigure4.4.EachstoragecelliscomposedofBoralabsorberpanelspositioned betweena8.75-inch I.D.,0..075-inch thickinnerstainless steelbox,anda0.035-inch outerstainless steelsheathwhichformsthewalloftheadjacentcell.Thefuelassemblies arenormallylocatedinthecenterofeachstoragecellonanominallatticespacingof8.97+0.04inches.TheBoralabsorberhasathickness of0.101+0.005inchandanominalB-10arealdensityof0.0345g/cm.4-9 f'll'lI1wIKI 4'4.4.1AnalicalMethodolo Reference DesinCalculations Inthefuelrackanalyses, theprimarycriticality analysesofthehighdensityspentfuelstoragerackswereperformed withtheKENO-(1).~*5acomputercodepackage,'singthe27-groupSCALEcross-section libraryandtheNITAWLsubroutine forU-238resonance shielding effects(Nordheim integraltreatment).

Depletion analysesanddetermination ofequivalent enrichments weremadewiththetwo-dimensional transport theorycode,CASMO-3.Benchmark

/calculations, presented inAppendixA,indicateabiasof0.0000withanuncertainty of+0.0024forCASMO-3and0.0090+0.0021(954/954) forNITAWL-KENO-Sa.

Intrackinglong-term (30-year) reactivity effectsofspentfuelstored'inRegion2ofthefuelstoragerack,previousCASMOcalculations confirmed acontinuous reduction inreactivity withtime(afterXedecay)dueprimarily toPu-241decayandAm-241growth.KENO-SaMonteCarlocalculations inherently includeastatistical uncertainty duetotherandomnatureofneutrontracking.

Tominimizethestatistical uncertainty oftheKENO-calculated reactivity, aminimumof500,000neutronhistories in1000generations of500neutronseach,areaccumulated ineachcalculation.

Forthedesigncalculation fortheracks,1,250,000 histories wereusedtoconfirmconvergence oftheKENO-5acalculation.

Figure4.5represents thebasicgeometric modelusedintheKENO-5acalculations.

Thismodeleffectively describes arepeating arrayof10storagecellsintheX-direction separated bya2-inchwater"SCALE"isanacronymforStandardized ComputerAnalysisforlicensing

/valuation, astandardcross-section setdeveloped byORNLfortheUSNRC.4-10 LIItII gapbetweenmodulesandaninfinitearrayofcellsintheY-direction (periodic boundaryconditions).

Intheaxial(Z)direction, thefulllength144-inchfuelassemblywasdescribed witha30-cmwaterreflector.

Asimiliarmodelwasusedforcalculations oftherackperipheral cellswherethecalculations weremadewithbothwaterandconcretereflectors (aconcretereflector gaveaslightlyhigherreactivity by0.004Sk).Largermodels,encompassing anentirestoragemodule(halfofan11x11array,runfor1,250,000 neutronhistories toassureconvergence) confirmed resultsobtainedwiththesmallerinfinitearraymodel.Thelargermodelwasalsousedtoconfirmthereactivity calculation forthecheckerboard arrangement withfreshfuelandemptycellsinRegion3andintheinvestigation oftheconsequences ofpotential accidentconditions withamisplaced freshfuelassembly.

Inaddition, thecornerintersection wasexplicitly modeledand,as.expected, gavealowerreactivity thanthereference designcalculation.

IntheCASMO-3geometric model(cell),eachfuelrodanditscladdingweredescribed explicitly andreflecting boundaryconditions (zeroneutroncurrent)wereusedintheaxialdirection andatthecenterline oftheBoralandsteelplatesbetweenstoragecells.Theseboundaryconditions havetheeffectofcreatinganinfinitearrayofstoragecellsinalldirections andprovideaconservative estimateoftheuncertainties inreactivity attributed tomanufacturing tolerances.

BecauseNITAWL-KENO-5a doesnothaveburnupcapability, burnedfuelwasrepresented byfuelofequivalent enrichment asdetermined byCASMO-3calculations inthestoragecell(i.e.anenrichment whichyieldsthesamereactivity inthestoraecellastheburnedfuel).4-11 lIII Figure4.6showsthisequivalent enrichment.

forfuelof4.954initialenrichment atvariousdischarge burnups,evaluated inthestoragecell.4.4.2FuelBurnuCalculations andUncertainties CASMO-3wasusedforburnupcalculations inthehotoperating condition.

CASMO-3hasbeenextensively benchmarked (Appendix AandRefs.2and7)againstcriticalexperiments (including plutonium-bearing fuel).Inadditiontoburnupcalculations, CASMO-3wasusedforevaluating thesmallreactivity increments (bydifferential calculations) associated withmanufacturing tolerances.

Sincetherearenocriticalexperiment datawithspentfuelfordetermining theuncertainty inburnup-dependent reactivity calculations, anallowance foruncertainty inreactivity wasassignedbasedupontheassumption of54uncertainty inburnup.Thisisapproximately equivalent to54ofthetotalreactivity decrement.

Atthedesignbasisburnupsof38and50MWD/KgU,theuncertainties inburnupare+1.9and+2.5=MWD/KgU respectively.

Toevaluatethereactivity consequences oftheuncertainties inburnup,independent calculations weremadewithfuelof36,100and47,500MWD/MtUburnupinRegions2and3,andtheincremental changefrom.thereference burnupsassumedtorepresent thenetuncertainties inreactivity.

Thesecalculations resultedinanincremental reactivity uncertainty of+0.0047SkinRegion2(isolation barrierat50MWD/KgUburnup)and+0.0019forRegion3(at38MWD/KgUburnup)..Intheracks,thefreshunburnedfuelinRegion1stronglydominatethereactivity whichtendstominimizethereactivity consequences ofuncertainties inburnup.The*Onlythatportionoftheuncertainty duetoburnup.Otheruncertainties areaccounted forelsewhere.

4-12 I4e allowance foruncertainty inburnupcalculations is'conservative

estimate, particularly inviewofthesubstantial reactivity decreasewithtimeasthespentfuelages.4.4.3EffectofAxialBurnuDistribution Initially, fuelloadedintothereactorwillburnwithaslightlyskewedcosinepowerdistribution.

Asburnupprogresses, theburnupdistribution willtendtoflatten,becomingmorehighlyburnedinthecentralregionsthanintheupperandlowerends,asmaybeseeninthecurvescompiledinRef.4.Athighburnup,themorereactivefuelneartheendsofthefuelassembly(lessthanaverageburnup)occursinregionsoflowerreactivity worthduetoneutronleakage.Consequently, itwouldbeexpectedthatovermostoftheburnuphistory,distributed burnupfuelassemblies wouldexhibitaslightlylowerreactivity thanthatcalculated fortheaverageburnup.Asburnupprogresses, thedistribution, tosomeextent,tendstobeself-regulating ascontrolled bytheaxialpowerdistribution, precluding theexistence oflargeregionsofsignificantly reducedburnup.Amongothers,Turnerhasprovidedgenericanalyticresultsoftheaxialburnupeffectbaseduponcalculated andmeasuredaxialburnupdistributions.

Theseanalysesconfirmtheminorandgenerally negativereactivity effectoftheaxiallydistributed burnup.Thetrendsobserved, however,suggestthepossibility ofasmallpositivereactivity effectathighburnup.Calculations weremadewithKENO-5ainthreedimensions, baseduponthetypicalaxialburnupdistribution ofspentfuel(thatobservedattheSurreyplantwastakenasrepresentative).

Xnthesecalculations, theaxialheightoftheburnedfuelwasdividedintoanumberofaxialzones(6-inchintervals nearthemoresignificant topofthefuel),eachwithanenrichment equivalent totheburnup4-13 IOlIl ofthatzone.Thesecalculations resultedinanincremental reactivity increaseof0.0037b'kforthereference designcase.Fueloflowerinitialenrichments (andlowerburnup)wouldhaveasmaller(ornegative) reactivity effectasaresultoftheaxialvariation inburnup.Theseestimates areconservative sincesmalleraxialincrements inthecalculations havebeenshowntoresultinlowerincremental reactivities 4-14 II 4.54.5.1Criticalit Analses'andTolerances NominalDesinForthenominalstoragecelldesign,theNlTAWL-KENO-Sa calculation resultedinabias-corrected kof0.9250+0.0012(9S%/95%),

which,whencombinedwithallknownuncertainties andtheaxialburnupeffect,resultsinakof0.929+0.011oramaximumkof0.940witha954probability atthe95:confidence levelFortheinterimloadingpatternofcheckerboarded fuelandemptycellsinRegion3,calculations resultedinessentially thesamereactivity asthereference designwithinthenormalKENO-5astatistics (maximumkof0.940,including allallowances anduncertainties, seeTable4.2).4Uncertainties DuetoManufacturin Tolerances Theuncertainties duetomanufacturing tolerances aresummarized inTable4-5anddiscussed below.4.5.2.1BoronLoadinTolerances TheBoralabsorberpanelsusedinthestoragecellsarenominally 0.101inchthick,7.50-inch wideand144-inchlong,withanominalB-10arealdensityof0.034Sg/cm.Thevendorsmanufacturing tolerance limitis+0.004Sg/cminB-10contentwhichassuresthatatanypoint,theminimumB-10arealdensitywillnotbelessthan0.030g/cm.Differential KENO-5acalculations forthereference designwiththeminimumtolerance B-10loadingresultsinanincremental reactivity of+0.00614Skuncertainty.

4-15 II1ll 4.5.2.2BoralWidthTolerance Thereference storagecelldesignusesaBoralpanelwithaninitialwidthof7.50+0.06inches.Forthemaximumtolerance of0.06inch,thedifferential CASMO-3calculated reactivity uncertainty is+0.0009Sk.4.5.2.3Tolerances inCellLatticeSacinThemanufacturing tolerance ontheinnerboxdimension, whichdirectlyaffectsthestoragecelllatticespacingbetweenfuelassemblies, is+0.06inches.Thiscorresponds toanuncertainty inreactivity of+0.0015Skdetermined bydifferential CASNO-3calculations.

4.5.2.4Stainless SteelThickness Tolerances Thenominalstainless steelthickness is0.075+0.005inchfortheinnerstainless steelboxand0.035+0.003inchfortheBoralcoverplate.Themaximumpositivereactivity effectoftheexpectedstainless steelthickness tolerances wascalculated (CASMO-3) tobe+0.0009Sk.4.5.2.5FuelEnrichment andDensitTolerances Thedesignmaximumenrichment is4.95+0.05wt%U-235.SeparateCASMO-3burnupcalculations weremadeforfuelofthemaximumenrichment (5.004)andforthemaximumUO>density(10.50g/cc).Reactivities inthestoragecellwerethencalculated usingtherestartcapability inCASMO-3andequivalent enrichments determined forthereference fuelburnupsof38and50MWD/KgU.Theincremental reactivities betweenthesecalculations andthereference CASMO-3cases,wereconservatively takenasthe4-16 lI sensitivity'to smallenrichment anddensityvariations.

Forthetolerance onU-235enrichment, theuncertainty inkis+0.00346kandforfueldensityis+0.0035.4.5.3Water-aSacinBetweenModulesThewater-gap betweenmodulesconstitute aneutronflux-trap fortheouter(peripheral) rowofstoragecells.Calculations withKENO-5aweremadeforvariouswater-gap spacings(Figure4.7).Fromthesedata,itwasdetermined thattheincremental reactivity consequence (uncertainty) fortheminimumwater-gap tolerance of+1/4inchis+0.00456k.Theracksaresonstructed withthebaseplateextending beyondtheedgeofthecells.Thisassuresthataminimumspacingof1.75inchbetweenstoragemodulesismaintained underallcredibleconditions.

4.5.4ccentricFuelPositionin Thefuelassemblyisassumedtobenormallylocatedinthecenterofthestoragerackcell.Infinitearraycalculations weremadeusingKENO-5aforasinglecellwiththefuelassemblies centeredandwiththeassemblies assumedtobeinthecornerofthestoragerackcell(four-assembly clusteratclosestapproach).

Thesecalculations indicated thatthereactivity uncertainty couldbeasmuchas+0.00196k.4.64~6~1AbnormalandAccidentConditions TemeratureandWaterDensitEffectsThemoderator temperature coefficient ofreactivity isnegative; amoderator temperature of20'C(68'F)wasassumedforthereference designs,whichassuresthatthetruereactivity willalwaysbelowerovertheexpectedrangeofwatertemperatures.

Temperature 4-17 IIIVIII effectsonreactivity havebeencalculated andtheresultsareshowninTable4.6.Withsolublepoisonpresent,thetemperature coefficients ofreactivity woulddifferfromthoseinferredfromthedatainTable4.6.However,thereactivities wouldalsobesubstantially loweratalltemperatures withsolubleboronpresent,andthedatainTable4.6ispertinent tothehigher-reactivity unborated case.4.6'DoedFuelAssemblForadropontopoftherack,thefuelassemblywillcometoresthorizontally ontopoftherackwithaminimumseparation distancefromthefuelintherackofmorethan12inches,including

'thepotential deformation underseismicoraccidentconditions.

Atthisseparation

distance, theeffectonreactivity isinsignificant

(<0.00016'k).Furthermore, solubleboroninthepoolwaterwouldsubstantially reducethereactivity andassurethatthetruereactivity isalwayslessthanthelimitingvalueforanyconceivable droppedfuelaccident.

4.6.3ateralRackMovementLateralmotionoftherackmodulesunderseismicconditions couldpotentially alterthespacingbetweenrackmodules.However,themaximumrackmovementhasbeendetermined tobelessthanthetolerance onthewater-gap spacing.Furthermore, solublepoisonwouldassurethatareactivity lessthanthedesignlimitation ismaintained underallaccidentorabnormalconditions.

4-18 IIIII 4.6.4AbnormalLocationofaFuelAssemblTheabnormallocationofafreshunirradiated fuelassemblyof4.95wt4enrichment could,intheabsenceofsolublepoison,resultinexceeding thedesignreactivity limitation (kof0.95).Thiscouldoccurifafreshfuel'ssembly ofthehighestpermissible enrichment weretobeeitherpositioned outsideandadjacenttoastoragerackmoduleorinadvertently loadedintoeitheraRegion2orRegion3storagecell.Calculations (KENO-5a) showedthatthehighestreactivity, including uncertainties, fortheworstcasepostulated

accident, condition (freshfuelassemblyinRegion2)wouldexceedthelimitonreactivity intheabsenceofsolubleboron.Solubleboroninthespentfuelpoolwater,forwhichcreditispermitted undertheseaccidentconditions, wouldassurethatthereactivity ismaintained substantially lessthanthedesignlimitation.

Itisestimated thatasolublepoisonconcentration of550ppmboronwouldbesufficient tomaintainkatthereference designvalueof0.940underthemaximumpostulated accidentcondition.

Approximately 450ppmboronwouldberequiredtolimitthemaximumreactivity toak~ffof0.95.4.7ExistinSentFuelAsofMay1990,therewere1596spentfuelassemblies instorageattheDonaldC.Cookplant,including thosenowinthereactorandtheirprojected burnupsatdischarge.

Figure4.8superimposes theenrichment-burnup combination ofthesefuelassemblies onthecurvesdefiningtheacceptable burnupdomains.Asmaybeseeninthisfigure,mostofthespentfuelnowinstoragefallswellintotheacceptable domainforthebarrierfuel(Region2).Thenumberoffuelassemblies meetingtheenrichment-burnup criteriaforstorageinRegion2is1390whichwillnearlyfillthe1447Region2storagelocations.

Twelvefuelassemblies (discharged 4-19 IIII prematurely forvariousreasons)willneedtobekeptinaRegion1storagelocation, andtheremaining 194assemblies maybes'toredinRegion3locations.

Futuredischarge batchesmayreasonably beexpectedtohaveapreponderance ofhighlyburnedfuelcapableofbeingstoredinRegion2(orinRegion3onceRegion2isfilled).Anappreciable numberofspentfuelassemblies haveenrichment-burnupcombinations wellinexcessofthedesignbasisand,thisprovidesfurtherconservatism inthecriticality safetyofthespentfuelstoragerackdesign.4-20 IlII 4.8References Green,Lucious,Petrie,Ford,White,andWright,"PSR-63-/NXTAWL-1 (codepackage)NITAWLModularCodeSystemForGenerating CoupledMultigroup Neutron-Gamma Libraries fromENDF/B",ORNL-TM-3706, OakRidgeNationalLaboratory, November1975.2~3.4~5.6.R.M.Westfallet.al.,"SCALE:AModularSystemforPerforming Standardized ComputerAnalysisforLicensing Evaluation",

NUREG/CR-0200, 1979.Volume2,SectionF11,"KENO-5aAnImprovedMonteCarloCriticality ProgramwithSupergrouping".

A.Ahlin,M.Edenius,andH.Haggblom, "CASMO-AFuelAssemblyBurnupProgram",

AE-RF-76-4158, Studsvikreport.A.AhlinandM.Edenius,"CASMO-AFastTransport TheoryDepletion CodeforLWRAnalysis",

ANSTransactions, Vol.26~p604I1977~"CASMO-3AFuelAssemblyBurnupProgram,UsersManual",Studsvik/NFA-87/7, StudsvikEnergitechnik AB,November1986H.Richings, SomeNotesonPWR(W)PowerDistribution Probabilities forLOCAProbabilistic

Analyses, NRCMemorandum toP.S.Check,datedJuly5,1977.S.E.Turner,"Uncertainty Analysis-BurnupDistribu-tions",presented attheDOE/SANDIA Technical MeetingonFuelBurnupCredit,SpecialSession,ANS/ENSConference, Washington, D.C.,November 2,1988M.G.Natrella, Experimental Statistics NationalBureauofStandards, Handbook91,August1963.4-21 IIIIII Table4.1SUMMARYOFCRITICALITY SAFETYANALYSESNORMALSTORAGECONFIGURATION DesignBasisburnupsat4.954+0.054initialenrichment Temperature foranalysisReference k(KENO-5a)

Calculational bias,SkUncertainties Biasstatistics (954/954)

KENO-5astatistics (954/95%)

Manufacturing Tolerances Water-gap Fuelenrichment FueldensityBurnup(38MWD/KgU)Burnup(50MWD/KgU)Eccentricity inpositionStatistical combingion ofuncertainties AxialBurnupEffectTotalMaximumReactivity (k)0inRegion150inRegion238inRegion320C(68F)0.91600.0090+0.0021+0.0012+0.0064+0.0045+0.0034+0.0035+0.0019+0.0047+0.0019+0.01100.00370.9287+0.01100.940SeeAppendixASquarerootofsumofsquares.(2)4-22 III Table4.2SUMMARYOFCRITICALITY SAFETYANALYSESINTERIMCHECKERBOARD LOADINGDesignBasisburnupsat4.954+0.054initialenrichment Temperature foranalysisReference k(KENO-5a)

Calculational bias,6k0inRegion150inRegion2Region3-CHECKERBOARD (FRESHFUELANDEMPTY)20~C(684F)0.91680.0090Uncertainties (Assumedsameasthereference case)Biasstatistics (954/954)

KENO-5astatistics (954/954)

Manufacturing Tolerances Water-gap Fuelenrichment FueldensityBurnup(38MWD/KgU)Burnup(50MWD/KgU)Eccentricity Statistical combination ofuncertainties AxialBurnupEffectTotalMaximumReactivity (k)+,0.0021+0.0012+0.0064'0.0045+0.0034+0.0035NA+,0.0047+0.0019+0.01080.00370.9295+0.01080.940SeeAppendixASquarerootofsumofsquares.(2)4-23 IIIIIIII Table4.3REACTIVITY EFFECTSOFABNORMALANDACCIDENTCONDITIONS Accident/Abnormal Conditions Reactivity EffectTemperature increase(above684F)Void(boiling)

AssemblydroppedontopofrackLateralrackmodulemovementMisplacement ofafuelassemblyNegative(Table4.6)Negative(Table4.6)Negligible

(<0.0001Sk)(Included inTolerances)

Positive(0.065Max6k)(controlled bysolublepoison)4-24 IIII Table4.4DESIGNBASISFUELASSEMBLYSPECIFICATIONS FUELRODDATAOutsidediameter, in.Claddingthickness, in.Claddinginsidediameter, in.CladdingmaterialPelletdensity,4T.D.Stackdensity,gUO>/ccPelletdiameter, in.Maximumenrichment, wt4U-2350.4220.02430.3734Zr-495.010.29+0.200.3659495+0.05FUELASSEMBLYDATAFuelrodarrayNumberoffuelrodsFuelrodpitch,in.Numberofcontrolrodguideandinstrument thimblesThimbleO.D.,in.(nominal)

ThimbleI.D.,in.(nominal) 15x152040'630.5330.4994-25 IIIIII Table4.5Reactivity EffectsofManufacturing Tolerances Tolerance Incremental Reactivit SkBoron-10loading(+0.0045g/cm)BoralWidth(+1/16inch)Latticespacing(+0.04inch)Stainless Thickness

(+0.005inch)0.00610.00090.00150.0009Total(statistical sum)+0.00644-26 I

Table4.6EFFECTOFTEMPERATURE ANDVOIDONCALCULATED REACTIVITY OFSTORAGERACKCaseIncremental Reactivity Change,SkRegion1Region220oC(68oF)40oC(104oF)66C(150F)90C(194F)122C(252F)Reference

-0.003-0.009-0013-0.024122C(252F)+204void-0.071Reference

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2"WATERGAPWITHREFLECTING BOUNDARYCONDITIONS ORREFLECTOR (WATERORCONCRETE)

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2CPPENDIX ABENCHMARK CALCULATIONS byStanleyE.Turner,PhD,PEHOLTECINTERNATIONAL January1991 I

1.0INTRODUCTION

ANDSUM~YThe.objective ofthisbenchmarking studyistoverifyboththeNITAWL-KENO-5a(

~)methodology withthe27-groupSCALEcross-section libraryandtheCASMO-3code()foruseincriticality safetycalculations ofhighdensityspentfuelstorageracks.Bothcalculational methodsarebasedupontransport theoryandhavebeenbenchmarked againstcriticalexperiments thatsimulatetypicalspent.fuelstoragerackdesignsasrealistically aspossible.

Resultsofthesebenchmark calculations withbothmethodologies areconsistent withcorresponding calculations reportedintheliterature.

Resultsofthebenchmark calculations showthatthe27-group(SCALE)NITAWL-KENO-5a calculations consistently under-predictthecriticaleigenvalue by0.0090+0.0021Sk(witha95<probability ata954confidence level)forcriticalexperiments<)

thatareasrepresentative aspossibleofrealistic spentfuelstoragerackconfigurations andpoisonworths.Extensive benchmarking calculations ofcriticalexperi-mentswithCASMO-3havealsobeenreported<),

givingameank,<of1.0004+0.0011for37cases.WithaK-factorof2.14<@for954probability ata954confidence level,andconservatively neglect-ingthesmalloverprediction, theCASMO-3biasthenbecomes0.0000+0.0024.CASMO-3andNITAWL-KENO-5a intercomparison calculations ofinfinitearraysofpoisonedcellconfigurations (representative oftypicalspentfuelstoragerackdesigns)showverygoodagreement, confirming that0.0000+0.0024isareasonable biasanduncertainty forCASMO-3calculations.

Reference 5alsodocuments goodagreement ofheavynuclideconcentrations fortheYankeecoreisotopics, agreeingwiththemeasuredvalueswithinexperimental A-1 lIIII Thebenchmark calculations reportedhereconfirmthateitherthe27-group(SCALE)NITAWL-KENO orCASMO-3calculations areacceptable forcriticality analysisofhigh-density spentfuelstorageracks.Reference calculations fortherackdesignsshouldbeperformed withbothcodepackagestoprovideindependent verification.

2.0NITAWL-KENO 5aBENCHMARK CALCULATIONS AnalysisofaseriesofBabcock&Wilcoxcriticalexperiments(,

including somewithabsorberpanelstypicalofapoisonedspentfuelrack,issummarized inTable1,ascalculated withNITAWL-KENO-5a usingthe27-groupSCALEcross-section librayandtheNordheimresonance integraltreatment inNITAWL.DancofffactorsforinputtoNITAWLwerecalculated withtheOakRidgeSUPERDANroutine(fromtheSCALE()systemofcodes).Themeanforthesecalculations is0.9910+0.0033(1ostandarddeviation ofthepopulation).

Withaone-sided tolerance factorcorresponding to95<probability ata954confidence level(@,thecalculational biasis+0.0090withanuncertainty of+0.0021forthesixteencriticalexperiments analyzed.

Similarcalculational deviations havebeenreportedbyORNLforsome54criticalexperiments (mostlycleancriticalwithoutstrongabsorbers),

obtaining ameanbiasof0.0100+0.0013(954/954).

Thesepublished resultsareingoodagreement withtheresultsobtainedinthepresentanalysisandlendfurthercredencetothevalidityofthe27-groupNITAWL-KENO-5a calculational modelforuseincriticality analysisofhighdensityspentfuelstorageracks.Notrendsink,zwithintra-assembly watergap,withabsorberpanelreactivity worth,withenrichment orwithpoisonconcentration wereidentified.

A-2

)

Additional benchmarking calculations werealsomadeforaseriesofFrenchcriticalexperiments

)at4.754enrichment andforseveraloftheBNWLcriticals with4.264enrichedfuel.AnalysisoftheFrenchcriticals (Table2)showedatendencytooverpredict thereactivity, aresultalsoobtainedbyORNL.Thecalculated k,<valuesshowedatrendtowardhighervalueswithdecreasing coresize.Intheabsenceofasignificant enrichment effect(seeSection3below),thistrendandtheoverprediction isattributed toasmallinadequacy inNITAWL-KENO-5a incalculating neutronleakagefromverysmallassemblies.

Similaroverprediction wasalsoobservedfortheBR<Lseriesofcriticalexperiments<

>,whichalsoaresmallassemblies (although significantly largerthantheFrenchcriticals).

Inthiscase(Table2),theoverprediction appearstobesmall,givingameank<<of0.9990+0.0037(1crpopulation standarddeviation)

.BecauseofthesmallsizeoftheBNWLcriticalexperiments andtheabsenceofanysignificant enrichment effect,theoverprediction isalsoattributed tothefailureofNITAWL-KENO-5a toadequately treatneutronleakageinverysmallassemblies.

Sincetheanalysisofhigh-density spentfuelstorageracksgenerally doesnotentailneutronleakage,theobservedinadequacy ofNITAWL-KENO-5a isnotsignificant.

Furthermore, omittingresultsoftheFrenchandBNWLcriticalexperiment analysesfromthedetermination ofbiasisconservative sinceanyleakagethatmightenterintotheanalysiswouldtendtoresultinoverprediction ofthereactivity.

A-3 I

3.CASMO-3BENCHMARK CALCULATIONS TheCASMO-3codeisamultigroup transport theorycodeutilizing transmission probabilities toaccomplish two-dimensional calculations ofreactivity anddepletion forBWRandPWRfuelassemblies.

Assuch,CASMO-3iswell-suited tothecriticality analysisofspentfuelstorageracks,sincegeneralpracticeistotreattheracksasaninfinitemediumofstoragecells,neglecting leakageeffects.CASMO-3isamodification oftheCASMO-2Ecodeandhasbeenextensively'benchmarked againstbothmixedoxideandhotandcoldcriticalexperiments byStudsvikEnergiteknik

).Reportedana-lyses@of37criticalexperiments indicateameank<<of1.0004+0.0011(le).Toindependently confirmthevalidityofCASHO-3(andtoinvestigate anyeffectofenrichment),

aseriesofcalculations weremadewithCASMO-3andwithNITAWL-KENO-5a onidentical poisonedstoragecellsrepresentative ofhigh-density spentfuelstorageracks.Resultsoftheseintercomparison calculations (showninTable3)arewithinthenormalstatistical variation ofKENOcalculations andconfirmthebiasof0.0000+0.0024(954/954) forCASM0-3.Sincetwoindependent methodsofanalysiswouldnotbeexpectedtohavethesameerrorfunctionwithenrichment, resultsoftheintercomparison analyses(Table3)indicatethatthereisnosignificant effectoffuelenrichment overtherangeofenrich-mentsinvolvedinpowerreactorfuel.Furthermore, neglecting theFrenchandBNWLcriticalbenchmarking inthedetermination ofbiasisaconservative approach.

Intercomparison between,analytical methodsisatechnique endorsedbyReg.Guide5.14,"Validation ofCalculational MethodsforNuclearCriticality Safety".A-4 AEI REFERENCES TOAPPENDIXAGreen,Lucious,Petrie,Ford,White,andWright,>>PSR-63-/NITAWL-1 (codepackage)NITAWLModularCodeSystemForGenerating CoupledMultigroup Neutron-GAmma Libraries fromENDF/B>>,ORNL-TM-3706, OakRidgeNationalLaboratory, November1975.2.R.M.Westfallet.al.,"SCALE:AModularSystemforPerform-ingStandardized ComputerAnalysisforLicensing Evaluation",

NUREG/CR0200'979'~A.Ahlin,M.Edenius,andH.Haggblom, "CASMO-AFuelAssemblyBurnupProgram",

AE-RF-76-4158, Studsvikreport.A.AhlinandM.Edenius,>>CASMO-AFastTransport TheoryDepletion CodeforLWRAnalysis",

ANSTransactions, Vol.26,p.604,1977.>>CASMO-3AFuelAssemblyBurnupProgram,UsersManual>>,Studsvik/NFA-87/7, StudsvikEnergitechnik AB,November19864.M.N.Baldwinetal.,"Critical Experiments Supporting CloseProximity WaterStorageofPowerReactorFuel",BAW-1484-7, TheBabcock&WilcoxCo.,July1979.5.M.EdeniusandA.Ahlin,>>CASMO-3:

NewFeatures, Benchmarking, andAdvancedApplications",

NuclearScienceandEnineerin100/342-351/(1988)6.M.G.Natrella, Eerimental Statistics, NationalBureauofStandards, Handbook91,August1963.7~8.R.W.WestfallandJ.H.Knight,"SCALESystemCross-section Validation withShipping-cask CriticalExperiments",

QSTransactions, Vol.33,p.368,November1979S.E.TurnerandM.K.Gurley,>>Evaluation ofNITAWL-KENO Benchmark Calculations forHighDensitySpentFuelStorageRacks",ucleaScienceandEnineerinp80(2)230237,February1982.A-5 I

9.J.C.Manaranche, et.al.,"Dissolution andStorageExgeriment with4.754U-235EnrichedUOzRods",NuclearTechnolo,Vol.50,pp148,September 198010.S.R.Bierman,et.al.,"Critical Separation betweenSub-criticalClustersof4.29Wt.4UEnrichedUO>RodsinWaterwithFixedNeutronPoisons",

BatellePacificNorthwest Labora-tories,NUREG/CR/0073, May1978(withAugust1979errata).11.A.M.Hathout,et.al.,"Validation ofThreeCross-section Libraries UsedwiththeSCALESystemforCriticality Analy-sis",OakRidgeNationalLaboratory, NUREG/CR-1917, 1981.A-6 Il Table1RESULTSOF27-GROUP(SCALE)NZTAWL-KENO-5a CALCULATIONS OFB&WCRITICALEXPERIMENTS Experiment NumberCalculated kerrZZI"'XXIXZZZIZZXIVXZXMeanBiasBias(954/954) 0.99320.99150.99160.99180.99230.99190.99610.99600.98170.9843,0.99120.98660.99040.98610.99340.98740'9100.00900.0090+0.00161+0.0015+0.0013+0.0014+0.0015+0.0014+0.0015+0.0015+0.0015+0.0014+0.0015+0.0013+0.0014+0.0013+0.0013+0.0014+0.0014<'>

+0.0033@+0.0021Calculated fromindividual standarddeviations.

Calculated fromk,<valuesandusedasreference.

A-7 II Table2RESULTSOF27-GROUP(SCALE)NITAWL-KENO-5a CALCULATIONS OFFRENCHandBNWLCRITICALEXPERIMENTS Separation

Distance, cmFrenchExperiments CriticalHeight,'cmCalculated k,g02.55.010.023.824.4831.4764.341.0231+0.00361.0252+0.00431.0073+0.00130.9944+0.0014CaseBNWLExperiments Expt.No.Calculated keaNoAbsorberSSPlates(1.05B)SSPlates(1.62B)SSPlates(1.62B)SSPlatesSSPlatesZrPlates004/0320090110120130300.9964+0.00340.9988+0.00381.0032+0.00330.9986+0.00360.9980+0.00380.9936+0.00361.0044+0.0035Mean0.9990+0.0037A-8 Il Table3RESULTSOFCASMO-3ANDNITAWL-KENO-5a BENCEBGQK (INTERCOMPARISON)

CALCULATIONS Enrichment+

Wt.cU-235NITAWL-KENO-5a~

CASMO-3iSkl2.53.03.54.04.55.00.8385+0.00160.8808+0.00160.9074+0.00160.9311+0.00160.9546+0.00180'743+0.00180.90900.93460.95590.00160.00350.00130.97410.0002Mean0.00170.83790.00060.87760.0032Infinitearrayofassemblies typicalofhigh-density spent:fuelstorageracks.kfromNITAWL-KENO-5a corrected forbiasof0.0090Sk.A-9 IIIIl 5.0THERMAL-HYDRAULIC CONSIDERATIONS 5.1Introduction Aprimaryobjective inthedesignofthehighdensityspentfuelstorageracksfortheDonaldC.Cookspentfuelpoolistoensureadequatecoolingofthefuelassemblycladding.

Inthefollowing sectionabriefsynopsisofthedesignbasis,themethodofanalysis, andthenumerical resultsisprovided.

Similarmethodsofthermal-hydraulic analysishavebeenusedinpreviouslicensing effortsonhighdensityspentfuelracksforFermi2(Docket50-341),QuadCities1and2(Dockets50-254and50-265)gRanchoSeco(Docket50-312),GrandGulfUnit1(Docket50-416),OysterCreek(Docket50-219),VirgilC.Summer(Docket50-395),DiabloCanyon1and2(DocketNos.50-275and50-323),ByronUnits1and2(Docket50-454,455),St.LucieUnitOne(Docket50-335),Millstone PointI(50-245),

Vogtle.Unit2(50-425),KuoshengUnits1&2(TaiwanPowerCompany),

UlchinUnit2(KoreaElectricPowerCompany),

J.A.FitzPatrick (NewYorkPowerAuthority) andTMIUnit1(GPUNuclear).

wedoutfor-thethermal-hydraulic arraymaybebrokendownintotheandpoolbulkTheanalysestobecarr'ualif icationoftherackfollowing categories:

(i)Pooldecayheatevaluation temperature variation withtime.(ii)Determination ofthemaximumpoollocaltemperature attheinstantwhenthebulktemperature reachesitsmaximumvalue.5-1 IIIII (iii)Evaluation ofthemaximumfuelcladdingtemperature toestablish thatbulknucleateboilingatanylocationresulting intwophaseconditions environment aroundthefueldoesnotoccur.(iv)Evaluation ofthetime-to-boil ifallheatrejection pathsthroughthecoolingandcleanuparelost.(v)Computetheeffectofablockedfuelcellopeningonthelocalwaterandmaximumcladdingtemperature.

Thefollowing sectionspresentasynopsisofthemethodsemployedtoperformsuchanalysesandafinalsummaryoftheresults.5.2SentFuelCoolinSstemDescritionTheprincipal functions oftheSpentFuelCoolingSystemaretheremovalofdecayheatfromthespentfuelstoredinthepoolitservesandmaintaining theclarityof,andalowactivitylevelin,thewaterofthepool.Cleanup,ofpoolwaterisaccomplished bydiverting partoftheflow,maintained forremovalofdecayheat,throughfiltersand/ordemineralizers asdescribed inSection9.4ofUFSAR.52.1SstemFunctions TheSpentFuelPoolCoolingSystemisspentfuelpooltheheatgenerated byThesystemservesthespentfuelpooltwounits.designedtoremovefromthestoredspentfuelelements.whichissharedbetweenthe5-2 IIIII Thesystemdesignincorporates twoseparatecoolingtrains.Systempipingisarrangedso,thatfailureofanypipelinedoesnotdrainthespentfuelpoolbelowthetopofthestoredfuelelements.

5.2.2SstemDescritionEachofthetwocoolingloopsintheSpentFuelPoolCoolingSystemconsistsofapump,heatexchanger,

strainer, piping,associated valvesandinstrumentation.

Thepumpdrawswaterfromthepool,circulates itthroughtheheatexchanger andreturnsittothepool.Component coolingwatercoolstheheatexchanger.

Theclarityandpurityofthespentfuelpoolwaterismaintained bypassingapproximately 100gpmofthecoolingflowthroughafilteranddemineralizer.

Skimmersareprovidedtopreventdustanddebrisfromaccumulating onthesurfaceofthewater.Therefueling waterpurification pumpandfiltercanbeusedseparately orinconjunction withthespentfuelpooldemineralizer toregainrefueling waterclarityafteracrudburstineitherunit.Thiscanpreventlossoftimeduringrefueling duetopoorvisibility.

ThesystemisalsousedtomaintainwaterqualityintheRefueling WaterStorageTanksofbothunits.Thespentfuelpoolfilter/demineralizer isdownstream ofthespentfuelpoolcooler.Asaresult,thepoolpurification components aresubjected towatertemperatures whichcorrespond tothecooleroutlets(lessthan140'F).Allelementsofthepurification system,including theresins,arequalified for200Fdesigntemperature.

5-3 IIIIII Thespentfuelpoolpumpsuctionlinespenetrate thespentfuelpoolwallabovethefuelassemblies storedinthepooltopreventlossofwaterasaresultofasuctionlinerupture.Thepoolisinitially filledwithwateratthesameboronconcentration (2400ppm)asintherefueling waterstoragetank.Thespentfuelpoolislocatedoutsidethereactorcontainment.

Duringrefueling thewaterinthepoolcanbeisolatedfromthatinthere-fueling canalbyaweirgatesothatthereisonlyaverysmallamountofinterchange ofwaterasfuelassemblies aretransferred.

5.2.3Performance Reuirements Thefirstdesignbasisofthesystemisbasedonthenormalrefueling operation withanormalbatchof80assemblies beingremovedfromtheuniteachtime.Theseconddesignbasisforthesystemconsiders thatitispossibletounloadthereactorvessel(193fuelassemblies) formaintenance orinspection atatimewhenamaximumof3518spentfuelassemblies areassumedalreadystoredinthespentfuelpool.5.3DecaHeatLoadCalculations Thedecayheatloadcalculation isperformed inaccordance withtheprovisions ofUSNRCBranchTechnical PositionASB9-2,"Residual DecayEnergyforLightWaterReactorsforLongTermCooling",

Rev.2,July,1981.Forpurposesofthislicensing IIII application, itisassumedthatthepoolcontainsaninventory accumulated throughscheduled discharges from1975to2009(Table1.1.1).Further,sincethedecayheatloadincreases monotonically withreactorexposuretime,anupperboundof1260fullpoweroperation days(approximately 3.5years)isassumedforallstoredfuel.Thecumulative decayheatloadiscomputedfortheinstanceofhypothetical normaldischarge (21BinTable1.1.1)intheyear2009.AsshowninTable5.4.1,theratioofthisdecayheatloadduetotheinventory ofpreviously storedfueltotheaverageassemblyoperating powerPis0.3303.Thisdecayheatloadisassumedtoremaininvariant forthedurationofthepooltemperature evaluations performed inthewakeofnormalandfullcoreoffloadsdiscussed below.5.4DischareScenarios Thefollowing discharge scenarios areexamined:

Case1:Normaldischarge Anormalbatchof80assemblies with1260daysofreactorexposuretimeatfullpowerisdischarged inthepoolattheendofanormal18monthoperating cycle.Thereare43previously discharged batchesinthepool.Asdescribed later,thenormaldischarge isassumedtooccurattherateofapproximately 4assemblies perhourafter168hoursofdecayinthereactor.Onefuelpoolcoolingtrainisactiveandrunning.Onecoolingtraincontainsoneheatexchanger andonefuelpoolpump.Thiscaseisrunwiththedesignfuelpoolwaterflowrate(2300gpm)andactualavailable flowrate(2800gpm).ThesetwocasesarelabelledasCaselaandCase1b,respectively.

Case2:Normaldischarge SameasCase1excepttwofuelpoolcoolingtrainsareoperating.

5-5 IIIII Case3:Back-to-Back FullcoreoffloadThefullcoreoffloadcondition corresponds totheemergency reactoroffloadcondition whereintheshutdownofareactoroccurs30daysaftertheotherreactorshutdownforanormalrefueling.

Twocoolingtrainsareassumedtobeoperating inparallelaftertheshutdown.

Thedecaytimeofthecoreinthereactorandtherateofdischarge tothepoolare.thesameasinCasel.Case4:SameasCase3exceptonlyonecoolingtrainThiscaseislistedforreference only;itbasiscasebytheDonaldC.CookTechnical theUSNRCguidelines (NUREG-0800).

isinoperation.

isnotadesignSpecification orDetaileddataonthethreecasesaregiveninTable5.4.1to5.4.3.5.5BulkPoolTemeratureInordertoperformtheanalysisconservatively, theheatexchangers areassumedtobefouledtotheirdesignmaximum.Thus,thetemperature effectiveness, p,fortheheatexchanger utilizedintheanalysisisthelowestpostulated valuecalculated fromheatexchanger thermalhydraulic codes.pisassumedconstantinthecalculation.

Themathematical formulation canbeexplained withreference tothesimplified heatexchanger alignment ofFigure5.5.1.Referring tothespentfuelpool/cooler system,thegoverning differential equationcanbewrittenbyutilizing conservation ofenergy:dT=QL-QHx(5-1)QL=Pcons+Q(r)-QEV(T,t'a)5-6 IIIIIII where:C:Qz,-Thermalcapacitance ofthepool(netwatervolumetimeswaterdensityandtimesheatcapacity),

Btu/'F.Heatloadtotheheatexchanger, Btu/hr.Heatgeneration ratefromrecentlydischarged fuel,whichisaspecified functionoftime,z,Btu/hr.Pcons=PPo'eatgeneration ratefrom"old"fuel,Btu/hr.(Po=averageassemblyoperating power,Btu/hr.)QHX:HeatremovalratebytheheatexchangerI Btu/hr.QEy(T(ta)'eat losstothesurroundings, whichisafunctionofpooltemperature Tandambienttemperature ta,Btu/hr.QHXisanon-linear functionoftimeifweassumethetemperature effectiveness pisconstantduringthecalculation.

QHXcan,however,bewrittenintermsofeffectiveness pasfollows:QHX+tCtp(T-ti)(5-2)where:Wt.Coolantflowrate,lb./hr.Ct.Coolantspecificheat,Btu/lb.'F.

p:Temperature effectiveness ofheatexchanger.

5-7 IIII T:Poolwatertemperature,

'Fti:Coolantinlettemperature,

'Fto.CoolantoutlettemperatureI F.pisobtainedbyratingtheheatexchanger onaHoltecproprietary thermal/hydraulic computercode.Q(r)isspecified according totheprovisions of"USNRCBranchTechnical PositionASB9-2,"Residual DecayEnergyforLightWaterReactorsforLongTermCooling",

Rev.2,July,1981.Q(r)isafunctionofdecaytime,numberofassemblies, andin-coreexposuretime.Duringthefueltransfer, theheatloadinthepoolwillincreasewithrespecttotherateoffueltransferandequalstoQ(r)afterthefueltransfer.

QEVisanon-linear functionofpooltemperature andambienttemperature.

QEVcontainstheheatevaporation lossthroughthepoolsurface,naturalconvection fromthepoolsurfaceandheatconduction throughthepoolwallsandslab.Experiments showthattheheatconduction takesonlyabout4%ofthetotalheatlossI'5.5.1],

therefore, canbeneglected.

Theevaporation heatandnatureconvection heatlosscanbeexpressed as:QEVm1's+hCAs8(5-~)where:m:As'assevaporation rateIlb/hrft.Latentheatofpoolwater,Btu/lb.Poolsurfacearea,ft..2hc-Convection heattransfercoefficient atpoolsurface,Btu/ft.,hr.'F5-8

-I~~

8=T-ta.Thetemperature difference betweenpoolwaterandambientair,'FThemassevaporation ratemcanbeobtainedasanon-linear functionof8.We,therefore, havem=hD(8)(Wps-Was)(5-4)where:Wps~Humidityratioofsaturated moistairatpoolwatersurfacetemperature T.Was.hD(8):Humidityratioofsaturated moistairatambienttemperature taDiffusion coefficient atpoolwatersurface.hDisanon-linear functionof8,lb./hr.ft.'FThenon-linear singleorderdifferential equation(5-1)issolvedusingHoltec'sQ.A.validated numerical integration code"ONEPOOL".

Figures5.5.2through5.5.6providethebulkpooltemperature profilesforthenormaldischarge, andfullcoreoffloadscenarios respectively.

Table5.5.1givesthepeakwatertemperature,

'Icoincident time,andcoincident heatloadtothecoolerandcoincident heatlosstotheambientforthreecases.Thenextstepintheanalysisistodetermine thetemperature riseprofileofthepoolwaterifallforcedindirectcoolingmodesaresuddenlylost.Make-upwaterisprovidedwithafirehose.Clearly,themostcriticalinstantofloss-of-cooling iswhenpoolwaterhasreacheditsmaximumvalue.EtisassumedthatcoolingwaterisaddedthroughafirehoseattherateofGlb./hr.The5-9 I~~~~~~~LI coolingwaterisattemperature, tcool.The.governing enthalpybalanceequationforthiscondition canbewrittenasdT[C+G(Ct)(zzo)]=Pcons+Q(~+rins)+G(Ct)(tcool-T)d'r-')EVwherewaterisassumed.tohavespecificheatofunity,andthetimecoordinate zismeasuredfromtheinstantmaximumpoolwatertemperature isreached.-zoisthetimecoordinate whenthedirectaddition(firehose)coolingwaterapplication isbegun.tinsisthetimecoordinate measuredfromtheinstantofreactorshutdowntowhenmaximumpoolwatertemperature isreached.Tisthedependent variable(poolwatertemperature).

Forconservatism, QE~isassumedtoremainconstantafterpoolwatertemperature reachesandrisesabove170'F.AQ.A.validated.

numerical quadrature codeisusedtointegrate theforegoingequation.

Thepoolwaterheatuprate,time-to-boil,andsubsequent waterevaporation-time profilearegenerated andcompiledforsafetyevaluation.

Assumingnomake-upwater(G=0),thetime-to-boil outputresultsarepresented inTable5.5.2.Figures5.5.6through5.5.10showtheplotoftheinventory ofwaterinthepoolafterloss-of-coolant-to-the-pool condition begins.ZtisseenfromTable5.5.2thatsufficient timetointroduce manualcoolingmeasuresexistsandtheavailable timeisconsistent withotherPWRreactorinstallations.

5-10 I1~i~

5.6LocalPoolWaterTemeratureZnthissection,asummaryofthemethodology, calculations andresultsforlocalpoolwatertemperature ispresented.

5.6.1BasisZnordertodetermine anupperboundonthemaximumfuelcladdingtemperature, aseriesofconservative assumptions aremade.Themostimportant assumptions arelistedbelow:0Thefuelpoolwillcontainspentfuelwithvaryingtime-after-shutdown (rs).Sincetheheatemissionfallsoffrapidlywithincreasing rs,itisconservative toassumethatallfuelassemblies arefromthelatestbatchdischarged simultaneously intheshortestpossibletimeandtheyallhavehadthemaximumpostulated yearsofoperating timeinthereactor.Theheatemissionrateofeachfuelassemblyisassumedtobeequaland'aximum.

0Asshowninthepoollayoutdrawings, themodulesoccupyanirregular floorspaceinthepool.Forthe'ydrothermal

analysis, acirclecircumscribing theactualrackfloorspaceisdrawn(Fig.5.6.1).Ztisfurtherassumedthatthecylinderwiththiscircleasitsbaseispackedwithfuelassemblies atthenominallayoutpitch.0Theactualdowncomer spacearoundtherackmodulegroupvaries.Thenominaldowncomer gapavailable inthepoolisassumedtobethetotalgapavailable aroundtheidealized cylindrical rack;thus,themaximumresistance todownwardflowisincorporated intotheanalysis(Figs.5.6.2and5.6.3)(i.e.minimumgapbetweenthepoolwallandrackmodule,including seismickinematic effect).0Nodowncomer flowisassumedtoexistbetweentherackmodules.5-11

~~~I~~~~I'~~I 0TheANF17x17fuelassemblyhasbeenusedintheanalysiswhich,fromthethermal-hydraulic standpoint, boundsalltypesoffuelbundlesutilizedintheDonaldC.Cookreactor.0Noheattransferisassumedtooccurbetweenpoolwaterandthesurroundings (wall,etc.)5.6.2ModelDescritionXnthismanner,aconservative idealized modelfortherackassemblage isobtained.

Thewaterflowisaxisymmetric abouttheverticalaxisofthecircularrackassemblage, andthus,theflowistwo-dimensional (axisymmetric three-dimensional)

.Fig.5.6.2showsatypical"flowchimney"rendering ofthethermalhydraulics model.Thegoverning equationtocharacterize theflowfieldinthepoolcannowbewritten.Theresulting integralequationcanbesolvedforthelowerplenumvelocityfield(intheradialdirection) andaxialvelocity(in-cellvelocityfield),byusingthemethodofcollocation.

Thehydrodynamic losscoefficients whichenterintotheformulation oftheintegralequationarealsotakenfromwell-recognized sources(Ref.5.6.1)andwhereverdiscrepancies inreportedvaluesexist,theconservative valuesareconsistently used.Reference 5.6.2givesthedetailsofmathematical analysisusedinthissolutionprocess.Aftertheaxialvelocityfieldisevaluated, itisastraight-forwardmattertocomputethefuelassemblycladdingtemperature.

Theknowledge oftheoverallflowfieldenablespinpointing ofthestoragelocationwiththeminimumaxialflow(i.e,maximumwateroutlettemperatures).

Thisiscalledthemost"choked"location.

Znordertofindanupperboundonthetemperature inatypicalcell,it,isassumedthatitislocatedatthemostchokedlocation.

Knowingtheglobalplenumvelocityfield,therevised5-12

axialflowthroughthischokedcellcanbecalculated bysolvingtheBernoulli's equationfortheflowcircuitthroughthiscell.Thus,anabsoluteupperboundonthewaterexittemperature andmaximumfuelcladdingtemperature isobtained.

Inviewoftheseaforementioned assumptions, thetemperatures calculated inthismanneroverestimate thetemperature risethatwillactuallyoccurinthepool.,Holtec'scomputercodeTHERPOOL*,

basedonthetheoryofRef.5.6.2,automates thiscalculation.

Theanalysisrprocedure embodiedinTHERPOOLhasbeenacceptedbytheNuclearRegulatory Commission onseveraldockets.TheCodeTHERPOOLforlocaltemperature analysesincludesthecalculation ofvoidgenerations.

Theeffectofvoidontheconservation

equation, crudlayerintheclad,fluxtraptemperature duetogammaheating,andthecladstresscalculation whenavoidexists,areallincorporated inTHERPOOL.

ThepeakingfactorsaregiveninTable5.6.1.5.7CladdinTemeratureThemaximumspecificpowerofafuelarray~canbegivenby:M=qFxywhere:Fxy=radialpeakingfactorq=averagefuelassemblyspecificpower*THERPOOLhasbeenusedinqualifying thespentfuelpoolsforEnricoFermiUnit2(1980),QuadCitiesIandII(1981)gOysterCreek(1984),V.C.Summer(1984),RanchoSeco(1983)fGrandGulfI(1985),DiabloCanyonIandII(1986),amongothers.5-13 1l Themaximumtemperature riseofpoolwaterinthemostdisadvantageously placedfuelassemblyiscomputedforallloadingcases.Havingdetermined themaximumlocalwatertemperature inthepool,itisnowpossibletodetermine themaximumfuelcladdingtemperature.

AfuelrodcanproduceFztimestheaverageheatemissionrateoverasmalllength,whereFzistheaxialrodpeakingfactor.Theaxialheatdistribution inarodisgenerally amaximuminthecentralregion,andtapersoffatitstwoextremities.

Ztcanbeshownthatthepowerdistribution corresponding tothechoppedcosinepoweremissionrateisgivenbyq(x)=gAsinn(a+x)h+2awhere:h:activefuellengtha:choppedlengthatbothextremities inthepowercurvex:axialcoordinate withoriginatthebottomoftheactivefuelregionThevalueofaisgivenbywhere:hza1-2z1/2mFz112++2F2nFzz25-14 l

whereFzistheaxialpeakingfactor.)Thecladdingtemperature Tcisgovernedbydifferential equationwhichhastheformofathirdorderd3Td2TdT+al--a2-=f(x)dxdx2dxwhereal,a2andf(x)arefunctions ofx,andfuelassemblygeometric properties.

Thesolutionofthisdifferential equationwithappropriate boundaryconditions providesthefuelcladdingtemperature andlocalwatertemperature profile.Inordertointroduce someadditional conservatism intheanalysis, weassumethatthefuelcladdinghasacruddepositwhichresultsin.005F-sq.ft.-hr/Btu ofcrudresistance, whichcoverstheentiresurface.Table5.6.2providesthe.keyinputdataforlocaltemperature analysis.

Theresultsofmaximumlocalpoolwatertemperature andminimumlocalfuelcladdingtemperature arepresented inTable5.7.1.Thelocalboilingtemperature ofwaterisapproximately 242'Fat26'elowthefreewatersurfaceandhigheratlowerelevations.

Thelocationwherethelocalwatertemperature reachesitsmaximumvalueisdeeperthan26'elowthefreewatersurface,wherethecoincident boilingtemperature ofwaterisgreaterthan242'P.Itisshownthatthelocalpoolwatertemperature islowerthanthelocalboilingpointandtherefore, nucleateboilingwillnotoccurs5-15

Finally,itisnotedthatthefuelcladdingconsiderably lowerthanthetemperatures towhichsubjected insidethereactor.Therefore, itisthereissufficient marginagainstfuelcladdingspentfuelpool.temperature isthecladdingisconcluded thatfailureinthe5.8BlockedCellAnalsisCalculations arealsoperformed assumingthat50%ofthetopopeninginthethermally limitingstoragecellisblockedduetoahorizontally placed(misplaced) fuelassembly.

Thecorresponding maximumlocalpoolwatertemperature andlocalfuelcladdingtemperature dataarealsopresented inTable5.7.1.Thereisalsonoincidence oflocalized nucleateboilingofthepoolwaterorpotential forfuelcladdingdamage.5.9References forSection55.6.1GeneralElectricCorporation, R&DDataBooks,"HeatTransferandFluidFlow",1974andupdates.5.6.2Singh,K.P.etal.,"MethodforComputing theMaximumWaterTemperature inaFuelPoolContaining SpentNuclearFuel",HeatTransferEngineering, Vol.7,No.1-2Ipp.72-82(1986)~5-16 IlI Table5.4.1=-FUELSPECIFICPOWERANDPOOLCAPACITYDATATotalwatervolumeofPool:SpecificOperating PowerofaFuelAssembly:

Dimensionless decaypowerof"old"discharges:

635645gallons60.3E+06Btu/hr.0.33035-17

Table5.4.2DATAFORSCENARXOS 1through4CASENO.IaIbPoolthermalcapacityCxl0,Btu/F4.2414.2414.2414.2414.241No.ofCoolingTrainsNo.ofDischarges considered fortheAnalysisTimebetweenshutdowns, hr.720720CoolerInletTemp.,OF108.4108.4103.9101.4104'coolantFlowRate/cooler,10lb./hr.1.49149l.491.49l.49FuelPoolWaterFlowRate,10lb./hr.l.141.40l.14l.14l.14Temperature Effectiveness/

cooler,p0.39700430.39750.3979'.39875-18 II Table5.4.3DATAFORSCENARIOS 1THROUGH4CaseDischerge No.ofNo.lDAssemblies TimeAftershutdownwhenTransferBegins(hrs)OffloadExpo.T~eT'me(hrs)(hrs)laor1bDischarge 18016819.0730240Discharge 1Discharge 13(orDischarge 24(Fullcore)80808011316816816819.073024019.073024046.0010080302405-19 IIII Table5.5.1POOLBULKTEMPERATURE ANDHEATLOADDATACaseNo.Coincident CoolerDuty106Btu/hr.TmaxMax.PoolBulkTemp.,OpTimeCoincident o(afterreactorshutdown)

Coincident Evaporation HeptLoss,10~Btu/hr.lalb30.24130.6932.78750.69045.04159.54156'1131.57143'4176.912072061982222253.002.5780.6891.3956.8875-20 I

Table5.5.2TIME-TO-BOIL FORVARIOUSDISCHARGE SCENARIOS CaseNumberTime-to-Boil (hours)G=0GPMla1b7.828.2711.525.743.025-21 IIII Table5.6.1PEAKINGFACTORDATARadialBundlePeakingFactorTotalpeakingfactor1.652.405-22 IIII Table5.6.2DATAFORLOCALTEMPERATURE TypeofFuelAssemblyFuelCladdingOuterDiameter, inchesFuelCladdingInsideDiameter, inchesStorageCellinsideDimension, inchesActivefuellength,inchesNo.ofFuelRods/Assembly Operating PowerperFuelAssemblyPox6pBtu/hrCellpitch,inchesCellheight,inchesPlenumradius,feetMin.Bottomheight,inchesMin.gapbetweenpoolwallandouterrackperiphery, inches0.360.318.7514426460.38.9716829.34.751.55-23 IIIII Table5.7.1LOCALANDCLADDINGTEMPERATURE OUTPUTDATAFORTHEMAXIMUMPOOLWATERCONDITION (Casea)Condition WaterTem.'FTem.'FNoblockage50%blockage168.0219.2212.9246.95-24 lIII W,TSPERTFUE'QQL.l,,7Ã,CP~,Tj4~FIGURE5.5.1PoolBulkTemperature Model5-25 IIII 165163DONALDC.COOKSFPNORMALDISCHARGE, ONECOOLINGTRAIN,CASE1a160158~155IJJ1530150ca14814514013850100150200250300350TIMEAFTERFIRSTSHUTDOWNOFTHEREACTOR,I.IRFIGURE5.5.2400450500 IIII 165163DONALDC.COOKSFPNORMALDISCHARGE, ONECOOLINGTRAIN,CASE1b160158155a.153~150o.Og14814514314013850100150200250300350TIMEAFTERFIRSTSHUTDOWNOFTHEREACTOR,HR400450500FIGURE5.5.3 III 135133DONALDC.COOKSFPNORMALDISCHARGE, TWOCOOLINGTRAINS,CASE2130~128OO12512312011850100150200250300350TIMEAFfERFIRSTSHUTDOWNOFTHEREACTOR,HRFIGURE5.5.4400450500 150145DONALDC.COOKSFPFULLCOREOFFLOAD,TWO COOLINGTRAINS,CASE3140135LBIUJ13000~125120115110100200300400500600700800900100011001200TIMEAFTERFIRSTSHUTDOWNOFTHEREACTOR.HRFIGURE5.5.5 IIIIIII 185180DONALDC.COOKSFPFULLCOREOFFLOAD,ONECOOLINGTRAIN,CASE4175170165o160~155OOQ.g150145140135130125100200300400500600700800900100011001200TIMEAFTERFIRSTSHUTDOWNOFTHEREACTOR,HRFIGURE5.5.6 II 5.50E+005 5.00E+0054,50E+005COOKSFPLOSSOFCOOLINGSCENARIO, CASE1a~4.00E+005 cc3.50E+005 0E~3.00E+005 IL<2.50E+005 02,00E+005E.o150E+0050~01.00E+005 5.00E+004.O,OOE+00004080120TimeAfterMax,temp.hasbeenreached,hrFIGURE5.5.7160 I

5.50E+005 5.00E+0054.50E+005 COOKSFPLOSSOFCOOLINGSCENARIO, CASE1bID4.OOE+OO5 Cc3.50E+005 oE~3.00E+005 VlIO2.50E+005 02,00E+005 o1.50E+005 0o1.00E+005 5.00E+004O.OOE+000 04080120TimeAfterMax.temp.hasbeenreached,hrFIGURE5.5.8160 IIIIIII 5.50E+005 5.00E+0054.50E+005 COOKSFPLOSSOFCOOLINGSCENARIO, CASE2>4.00E+005 c3.50E+005 0E~3.00E+005 I4J<2.50E+005 02.00E+005 01.50E+005 0~01.00E+005 5.00E+004 O.OOE+000 04080120TimeAfterMax.temp.hasbeenreached,hrFIGURE5.5.9160 IIIII 5.50E+005 5.00E+005 4.50E+005 COOKSFPLOSSOFCOOLINGSCENARIO, CASE3>4.00E+005 cc3.50E+005 0E~3.00E+005

>2.50E+005 02.00E+005 o1.50E+005 0~()1.00E+005 I-5.00E+004 O.OOE+000 0204060TimeAfterMax.temp.hasbeenreached,hrFIGURE5.5.j.o80 III~~I 5.50E+0055.00E+005 4.50E+005COOKSFPLOSSOFCOOLINGSCENARIO, CASE4u4.OOE+OO5 Cc3.50E+005 0ECL3.00E+005 02.50E+005 02.00E+00501.50E+005 0~~1.00E+005 I-5.00E+004.O,OOE+000 0204060TimeAfterMax.temp.hasbeenreached,hrFIGURE5.5.11.80 II I'I I

OUiP()D000ZI0QV~t~tZP+I~~0HEAiADDtiIGN tN5-37THERMALCHIMNEYFLOWMODELFlGLlRE5~6~2 III i$~~~~.44.4~r~~~0~~~RACK.40~e~~~~e4~g~~rh~~go~~rrd~~~~r~cf~V~~$~mgrrm~~~r'oS~rroawNCOMER5-38CONVECTION CVRRENTSINTHEPOOLFIGURE5.6.3 IIIIIII

6.0 STATICANDDYNAMICANALYSIS0RACKSTRUCTURE

6.1Introduction Thepurposeofthissectionistopresentanalyseswhichdemonstrate thestructural adequacyoftheDonaldC.Cookspentfuelhighdensityrackdesignundernormalstorageandthepostulated accidentloadingconditions asdefinedbyandfollowing theguidelines oftheUSNRCStandardReviewPlan(Ref.6.1.1).Themethodofanalysispresented usesatime-history integration methodsimilartothatpreviously usedinthelicensing reportsonhighdensityspentfuelracksforEnricoFermiUnit2(USNRCDocketNo.50-341),QuadCities1and2(USNRCDocketNos.50-254and50-265),RanchoSeco(USNRCDocketNo.50-312),GrandGulfUnit1(USNRCDocketNo.50-416),Oyster'Creek(USNRCDocketNo.50-219),V.C.Summer(USNRCDocketNo.50-395),DiabloCanyonUnits1and2(USNRCDocketNos.50-275and50-323),VogtleUnit2(USNRCDocketNo.50-425)andMillstone PointUnit1(USNRCDocketNo.50-245).TheanalysescarriedoutfortheDonaldC.Cookracksareconsiderably moreelaborate andexhaustive inscopeandsubstance thanthoseperformed intheaforementioned dockets,andreflectadvancesin3-Dfuelracksimulation technology inthepasttwoyears.Thedetailsarepresented laterinthissection,aftertheessential elementsofthedynamicmodelarefullyexplained.

Theresultsshowthatthehighdensityspentfuelracksarestructurally adequatetoresistthepostulated stresscombinations associated withlevelA,B,C,andDconditions asdefinedinRefs.6.1.1,6.1.2,and6.1.3.6-1 I

6.2AnalsisOutlineTheprincipal stepsinperforming theseismicanalysisofDonaldC.Cookracksaresummarized below:a0Developstatistically independent synthetic timehistories forthreeorthogonal directions whichsatisfyUSNRCSRP3.8.4.

Twotimehistories areconsidered tobestatistically independent iftheirnormalized correlation coefficient islessthan0.15.b.Prepareathree-dimensional dynamicmodelofthefuelrackwhichembodiesallelastostatic characteristics andstructural nonlinearities oftheDonaldC.Cookrackmodules.c~d.e.Performaseriesof3-DdynamicanalysesonalimitingmodulegeometrytypefromthoselistedinTables2.1.1and2'.3andforvaryingphysicalconditions (suchascoefficient offriction, extent.ofcellscontaining fuelassemblies, andproximity ofotherracks).Performstressanalysisforthecriticalcasefromthedynamicanalysisrunsmadeintheforegoing steps.Demonstrate compliance withASMECodeSectionIII,sub-sectionNF(Ref.6.1.2)limits.Carryoutadegree-of-freedom (DOF)reduction procedure onthesinglerack3-Dmodelsuchthatthekinematic responses calculated bythereducedDOF(modelRDOFM)areinagreement withthebaselinemodelofstep(b)above.ThisreducedDOFmodelisalsotrulythree-,dimensional.

Prepareawholepoolmulti-rack dynamicmodelbycompiling theRDOFM'sof~alrackmodulesinthepool,andbyincluding allfluidcouplinginteractions amongthem,aswellasthosebetweentheracksandpoolwalls.This3-Dmulti-module simulation isreferredtoasaWholePoolMulti-Rack (WPMR)model.6-2 lIl goPerforma3-DWholePoolMulti-Rack (WPMR)analysistodemonstrate thatallkinematic criteriaforDonaldC.Cookrackmodulesaresatisfied (seeSection6.8),andthatpedestalcompressive loadsarecomparable totheloadsusedforstructural qualification peritemdabove.Section6.8givesthecriteriawhichneedtobechecked.FortheDonaldC.Cookracks,theprincipal kinematic criteriaare(i)noracktopoolwallimpact,and(ii)norack-to-rack impactinthecellularregionoftheracks.Figure6.2.1showsapictorial viewoftherackmodule.Itisnotedthatthebaseplate extendsbeyondthecellularregion,envelope, thusensuringthattheinter-rack impact,ifany,wouldfirstoccuratthebaseplate elevation.

Thebaseplate oftherackmodulesisstructurally qualifiable towithstand largein-planeimpactloads.Wedescribeeachoftheaboveanalysisstepsinsomedetail,inthefollowing sub-sections withspecialemphasisonthebaseline3-Ddynamicmodelwhichisthebuildingblockforallsubsequentanalyses.

Wealsopresenttheresultsoftheanalysisintheconcluding sub-section.

6.3Artificial SlabMotionsTheUFSARprovidesasingleresponsespectruminthehorizontal direction andasingleresponsespectrumintheverticaldirection (2/3ofthehorizontal) fortheDesignBasisEarthquake (DBE).Acorresponding pairofspectraareprovidedfortheOperating BasisEarthquake (OBE).6-3 IIIII Holtec'sQ.A.validated timehistorygeneration codeGENEQ[6.3.1]wasusedtogeneratethreesynthetic statistically independent timehistories fortheNorth-South, East-West andverticaldirections, respectively, fromthetworesponsespectra.5%dampingisusedfortheDBEcondition.

Figures6.3.1-6.3.3showtheDBEtimehistoryplots.Responsespectracorresponding tothesetimehistories werealsogenerated andareshownoverlaidonthedesignspectrainFigures6.3.4-6.3.6.Thenormalized correlation coefficients pijbetweentimehistories iandj(1=N-S,2=E-W,3=vertical) areprovidedinTable6.3.1.TheaboveanalyseswererepeatedfortheOBEspectrausing2%damping.Figures6.3.7-6.3.9presentthetimehistoryplots,andFigures6.3.10-6.3.12showthecomparison betweenthedesignspectraandthederivedspectra.Table6.3.1alsoprovidespijfortheOBEtimehistories.

Xtisnotedthattheenveloping requirement onthederivedspectraandstatistical non-coherence ofartificial motionsareunconditional'ly satisfied.

6-4 III 6.4OutlineofSineRack3-DAnalsisThespentfuelstorageracksareSeismicClassIequipment.

Theyarerequiredtoremainfunctional duringandafteraDesignBasisEarthquake (Ref.6.1.3).Theseracksareneitheranchoredtothepoolfloornorattachedtothesidewalls.

Theindividual rackmodulesarenotinterconnected.

Furthermore, aparticular rackmaybecompletely loadedwithfuelassemblies (whichcorresponds togreatestrackinertia),

oritmaybecompletely empty.Thecoefficient offriction, p,betweenthesupportsandpoolfloorisanotherindeterminate factor.According toRabinowicz (Ref.6.4.1),theresultsof199testsperformed onaustenitic stainless steelplatessubmerged inwatershowameanvalueofptobe0.503withastandarddeviation of0.125.Theupperandlowerbounds(basedontwicethestandarddeviation) arethus0.753and0.253,respectively.

Analysesaretherefore performed forsingleracksimulations usingvaluesofthecoefficient offrictionequalto0.2(lowerlimit)and0.8(upperlimit),respectively.

Theboundingvaluesofp~0.2and0.8havebeenfoundtobrackettheupperlimitofthemoduleresponseinpreviousrerackprojects.

Asinglerack3-Danalysisrequiresanotherkeymodelling assumption.

Thisrelatestothelocationandrelativemotionofneighboring racks.Thegapbetweenaperipheral rackandanadjacentpoolwallisknown,andthemotionofthepoolwallisprescribed withoutanyambiguity.

However,anotherrackadjacenttotherackbeinganalyzedisalsofree-standing andsubjecttomotionduringaseismicevent.Toconducttheseismicanalysisofagivenrackitsphysicalinterface withneighboring modulesmustbespecified.

Thestandardprocedure inthesinglerackanalysisistospecifythattheneighboring.

racksmove180'ut-of-phase in6-5 II4II relationtothesubjectrack.Thus,theavailable gapbeforeinter-rack impactoccursisonehalfofthephysicalgap.This"opposedphasemotion"assumption increases thelikelihood ofpredicting intra-rack impactsandisthusaconservative assumption.

However,italsoincreases therelativecontribution offluidcouplingterms,whichdependonfluidgapsandrelativemovements ofbodies,makingtheoutrightconservatism alesscertainassertion.

Infact,3-DWholePoolMulti-rack analysescarriedoutforTaiwanPowerCompany's ChinShanStation,andforGPUNuclear's OysterCreekNuclearStationshowthatthesingleracksimulations predictsmallerrackdisplacement duringseismicresponses.

Nevertheless, singlerackanalysespermitdetailedevaluation ofstressfields,andserveasabenchmark checkforthemuchmoreinvolved, WPMRanalysisresults.Inordertopredictthelimitingconditions ofrackmoduleseismicresponsewithintheframework ofsinglerackanalysis, moduleA4(13x14)isanalyzed.

Thisistypicalofthelargestmodule,andisalsoacornermodule.Thecornermodulehaslargerrack-to-wall gapswhichwillminimizethefluidcoupling.

Therackisconsidered fullyloadedorhalfloaded,withlimitingcoefficients offriction; thesesimulations identifytheworstcaseresponseforrackmovementandforrackstructural integrity.

Aftercompletion ofreracking, thegapsbetweentherackmodulesIandthosebetweentheracksandwallswillbeinthemannerofFigure2.1.1.Weshowinthisreportthatallsinglerack3-Dsimulations predictthatnorack-to-rack orrack-to-wall impactswilloccurinthecellularregionoftheracks.Theseismicanalyseswereperformed utilizing thetime-history method.Poolslabacceleration datapresented inthepreceding sub-section wasused.6-6 IlWSIII Theobjective oftheseismicanalysisofsingleracksistodetermine thestructural response(stresses, deformation, rigidbodymotion,etc.)duetosimultaneous application ofthethreestatistically independent, orthogonal seismicexcitations.

Thus,recoursetoapproximate statistical summation techniques suchasthe"Square-Root-of-the-Sum-of-the-Squares" method(Ref.6.4-2)isavoided.Fornonlinear

analysis, theonlypractical methodissimultaneous application oftheseismicloadingtoanonlinear modelofthestructure.

Theseismicanalysisofasinglerackisperformed inthreesteps,namely:Development ofanonlinear dynamicmodelconsisting ofinertialmasselements, spring,gap,andfrictionelements.

2~3~Generation oftheequations ofmotionandinertialcouplingandsolutionoftheequations usingthe"component elementmethod"(Refs.6.4.3and6.4.4)todetermine nodalforcesanddisplacements.

TheHolteccomputercodeDYNARACKisusedtosolvethesystemofequations

[6.4.5].Computation ofthedetailedstressfieldintherackjustabovethebaseplate andinthesupportlegsismadeusingthenodalforcescalculated inthepreviousstep.Thesestressesarecheckedagainstthedesignlimitsgiveninalatersub-section.

Abriefdescription ofthedynamicmodelfollows.6.5DnamicModeforTheS'RacAnals'sSincetheracksarenotanchoredtothepoolslaborattachedtothepoolwallsortoeachother,theycanexecuteawidevarietyofmotions.Forexample,therackmayslideonthepoolfloor6-7 IIIIIII (so-called "slidingcondition"

);one'rmorelegsmaymomentarily losecontactwiththeliner("tippingcondition"

);ortherackmayexperience acombination ofslidingandtippingconditions.

Thestructural modelshouldpermitsimulationofthesekinematic eventswithinherentbuilt-inconservatisms.

Sincethemodulesaredesignedtoprecludetheincidence ofinter-rack impactinthecellularregion,itisalsonecessary toincludethepotential forinter-rack impactphenomena intheanalysistodemonstrate thatsuchimpactsdonotoccur.Lift-offofthesupportlegsandsubsequent linerimpactsmustbemodelledusingappropriate impact(gap)elements, andCoulombfrictionbetweentherackandthepoollinermustbesimulated byappropriate piecewise linearsprings.The'elasticity oftherackstructure, relativetothebase,mustalsobeincludedinthemodeleventhoughtherackmaybenearlyrigid.Thesespecialattributes ofrackdynamicsrequireastrongemphasisonthemodelingofthelinearandnonlinear springs,dampers,andcompression onlystopelements.

Thetermnon-linear springisthegenerictermtodenotethemathematical elementrepresenting thesituation wheretherestoring forceexertedbytheelementisnotlinearlyproportional tothedisplacement.

Inthefuelracksimulation theCoulombfrictioninterface betweentheracksupportlegandthelinerisatypicalexampleofanon-linearspring.Themodeloutlineintheremainder ofthissub-section,andthemodeldescription inthefollowing sub-section, describethe*detailedmodelingtechnique tosimulatetheseeffects,withconsiderable emphasisplacedonthenonlinearity oftherackseismicresponse.

6-8 IIIIIII 6.5.1ssumt'onsa."Thefuelrackstructure isafoldedmetalplateassemblage weldedtoabaseplate andsupported onfourlegs.Anodd-shapedmodulemayhavemorethanfourlegs.Therackstructure itselfisaveryrigidstructure.

Dynamicanalysisoftypicalmulti-cell rackshasshownthatthemotionofthestructure iscapturedalmostcompletely bymodelling therackasatwelvedegree-of-freedom structure, wherethemovementoftherackcross-section atanyheightisdescribed intermsofsixdegrees-of-freedom oftherackbaseandsixdegreesoffreedomdefinedattheracktop.TherattlingfuelismodelledbyfivelumpedmasseslocatedatH,.75H,.5Hg.25H,andattherackbase,whereHistherackheightasmeasuredfromthebase.b.Theseismicmotionofafuelrackischaracterized byrandomrattlingoffuelassemblies intheirindividual storagelocations.

Assumingacertainstatistical coherence (i.e.assumingthatallfuelelementsmovein-phasewithinarack)inthevibration ofthe.fuelassemblies exaggerates thecomputeddynamicloadingontherackstructure.

Thisassumption, however,greatlyreducestherequireddegrees-of-freedom neededtomodelthefuelassemblies whicharerepresented byfivelumpedmasseslocatedatdifferent levelsoftherack.Thecentroidofeachfuelassemblymasscanbelocated,relativetotherackstructure centroidatthatlevel,soastosimulateapartially loadedrack.c.Thelocalflexibility ofthepedestalismodelledsoastoaccountforfloorelasticity, andlocalrackelasticity justabove'hepedestal.

d.Therackbasesupportmayslideorlift-offthepoolfloor.e.Thepoolfloorhasaspecified time-history ofseismicaccelerations alongthethreeorthogonal directions.

if.Fluidcouplingbetweenrackandfuelassemblies, andbetweenrackandwall,issimulated byintroducing appropriate inertialcouplingintothesystemkineticenergy.Inclusion oftheseeffectsusesthemethodsofRefs.6.5.1and6.5.2forrack/assembly couplingandforrack/rack coupling.

6-9 g.Potential impactsbetweenrackandfuelassemblies areaccounted forbyappropriate "compression only"gapelementsbetweenmassesinvolved.

h.Fluiddampingduetoviscouseffectsbetweenrackandassemblies, andbetweenrackandadjacentrack,isconservatively neglected.

i.Thesupportsaremodeledas"compression only"elementsfortheverticaldirection andas"rigidlinks"fortransferring horizontal stress.Thebottomofasupportlegisattachedtoafrictional springasdescribed insub-section 6.6.Thecross-section inertialproperties ofthesupportlegsarecomputedandusedinthefinalcomputations todetermine supportlegstresses.

j.Theeffectofsloshingisnegligible atthelevelofthetopoftherackandishenceneglected.

k.Thepossibleincidence ofrack-to-wall orrack-to-rack impactissimulated bygapelementsatthetopandbottomoftherackinthetwohorizontal directions

.Thebottomelementsarelocatedatthebaseplate elevation.

1.Rattlingoffuelassemblies insidethestoragelocations causesthe"gap"betweenthefuelassemblies andthecellwalltochangefromamaximumoftwicethenominalgaptoatheoretical zerogap.Fluidcouplingcoefficients arebasedonthenominalgap.m.Theformdragduetomotionofthefuelassemblyinthestoragecell,orthatduetomovementofarackinthepool,hasbeenneglected inthisanalysisforaddedconservatism.

n.Thefluidcouplingtermsarebasedonopposedphasemotionofadjacentmodules.FigurefreedomFiguresspringsbetween6.5.1showsaschematic ofthemodel.Twelvedegreesofareusedtotrackthemotion'ftherackstructure.

6.5.2and6.5.3,respectively, showtheinter-rack impact(totrackthepotential forimpactbetweenracksorrackandwall)andfuelassembly/storage cellimpact6-10 IIIIII springsataparticular level.Si(i=1,4)represent supportlocations, pirepresent absolutedegrees-of-freedom, andqirepresent degrees-of-freedom relativetotheslab.Histheheightoftherackabovethebaseplate.

AsshowninFigure6.5.1,themodelforsimulating fuelassemblymotionincorporates fiverattlinglumpedmasses.Thefiverattlingmassesarelocatedatthebaseplate, atquarterheight,athalfheight,atthreequarterheight,andatthetopoftherack.Twodegrees-of-freedom areusedtotrackthemotionofeachrattlingmassinthehorizontal plane.Theverticalmotionofeachrattlingmassisassumedtobethesameastherackbase.Figures6.5.4,6.5.'5,and6.5.6showthemodelling schemeforincluding rackelasticity andthedegreesoffreedomassociated withrackelasticity.

Ineachplaneofbendingashearandabendingspringareusedtosimulateelasticeffectsinaccordance withRef.6.5.1.Table6.6.2givesspringconstants forthesebendingspringsaswellascorresponding constants forextensional andtorsional rackelasticity.

6.5.2ModeDescritioTheabsolutedegrees-of-freedom associated witheachofthemasslocations areidentified inFigure6.5.1andinTable6.5.1.Therattlingmasses(nodes1*,2*,3*,4*,5*)aredescribed bytranslational degrees-of-freedom q7-q16.Ui(t)isthepoolfloorslabdisplacement seismictime-history.

Thus,therearetwenty-two degreesoffreedominthesystem.NotshowninFig.6.5.1arethegapelementsusedtomodelthesupportlegsandtheimpactswithadjacentracks.6-11 III1,.yIII 6.5.3FluidCoulinAneffectofsomesignificance requiring carefulmodelingisthe"fluidcouplingeffect"(Refs.6.5.1and6.5.2).Ifonebodyofmass(m1)vibratesadjacenttoanotherbody(massm2),andbothbodiesaresubmerged inafrictionless fluidmedium,thenNewton'sequations ofmotionforthetwobodieshavetheform:NN(ml+Mll)Xl+M12X2appliedforcesonmassml+0(xl)M21Xl+(m2+M22)X2=appliedforcesonmassm2+0(x2)X1,X2denoteabsoluteaccelerations ofmassesm1andm2,respectively andthenotation0(x)denotesnon-linear termswhichariseinthederivation.

M11~M12M21,andM22arefluidcouplingcoefficients whichdependontheshapeofthetwobodies,theirrelativedisposition, etc.Fritz(Ref.6.5.2)givesdataforMijforvariousbodyshapesandarrangements.

Theaboveequations indicatethattheeffectofthefluidistoaddacertainamountofmasstothebody(M11tobody1),andanexternalforcewhichisproportional totheacceleration oftheadjacentbody(massm2).Thus,theacceleration ofonebodyaffectstheforcefieldonanother.Thisforceisastrongfunctionoftheinterbody gap,reachinglargevaluesforverysmallgaps.Thisinertialcouplingiscalledfluidcoupling.

Ithasanimportant effectinrackdynamics.

Thelateralmotionofafuelassemblyinsidethestoragelocationwillencounter thiseffect.Sowillthemotionofarackadjacenttoanotherrackiftheracksarecloselyspaced.Theseeffectsareincludedintheequations ofmotion.Forexample,thefluid6-12 I

couplingisbetweennodes2and2*inFigure6.5.1.Furthermore, therackequations containcouplingtermswhichmodeltheeffectoffluidinthegapsbetweenadjacentracks.Thecouplingtermsmodelingtheeffectsoffluidflowingbetweenadjacentracksarecomputedassumingthatalladjacentracksarevibrating 180outofphasefromtherackbeinganalyzed.

Therefore, onlyonerackisconsidered surrounded byahydrodynamic masscomputedasiftherewereaplaneofsymmetrylocatedinthemiddleofthegapregion.Finally,fluidvirtualmassisincludedintheverticaldirection vibration equations oftherack;virtualinertiaisalsoaddedtothegoverning equationcorresponding totherotational degreeoffreedom,q6(t)andq22(t).6.5a4~DaminZnreality,damping(Ref.6.5.3)oftherackmotionarisesfrommaterialhysteresis (material damping),

relativeintercomponent motioninstructures (structural damping),

andfluidviscouseffects(fluiddamping).

Zntheanalysis, amaximumof1%structural dampingisimposedonelementsoftherackstructure duringOBEandDBEsimulations.

Materialandfluiddampingduetofluidviscosity areconservatively neglected.

Thedynamicmodelhastheprovision toincorporate formdrageffects;however,noformdraghasbeenusedforthisanalysis.

6~5.5~ImactAnyfuelassemblynode(e.g.,2*)mayimpactthecorresponding structural massnode2.Tosimulatethisimpact,fourcompression-only gapelementsaroundeachrattlingfuelassembly6-13 II LLnodeareprovided(seeFigure6.5.3).Thecompressive loadsdeveloped inthesespringsprovidethenecessary datatoevaluatetheintegrity ofthecellwallstructure andstoredarrayduringtheseismicevent.Figure6.5.2showsthelocationoftheimpactspringsusedtosimulateanypotential forinter-rack orrack-to-wallimpacts.Sub-section 6.6givesmoredetailsontheseadditional impactsprings.Sincetherearefiverattlingmasses,atotalof20impactspringsareusedtomodelfuelassembly-cell wallimpact.6.6AssemblotheDnamicModelThe.cartesian coordinate systemassociated withtherackhasthefollowing nomenclature:

x~Horizontal coordinate alongtheshortdirection ofrackrectangular planformy=Horizontal coordinate alongthelongdirection oftherackrectangular planformz=Verticalcoordinate upwardfromtherackbaseLLTable6.6.1listsallspringelementsusedinthe3-Dsinglerackanalysis.

Ifthesimulation modelisrestricted totwodimensions (onehorizontal motionplusverticalmotion,forexample)gortheurosesofodcar'f'cat'o onlthenadescriptive modelofthesimulated structure whichincludesgapandfrictionelementsisshowninFigure6.6.1.Theimpactsbetweenfuelassemblies andrackshowupinthegapelements, havinglocalstiffness KI,inFigure6.6.1.InTable6.6.1,gapelements5through8areforthevibrating massatthe6-14

'topoftherack.ThesupportlegspringratesKSaremodeledbyelements1through4inTable6.6.1.Notethatthelocalcompliance oftheconcretefloorisincludedinKS.Tosimulateslidingpotential, frictionelements2plus8and4plus6(Table6.6.1)areshowninFigure6.6.1.Thefrictionofthesupport/liner interface ismodeledbyapiecewise linearspringwithasuitablylargestiffness Kfuptothelimitinglateralload,pN,whereNisthecurrentcompression loadattheinterface betweensupportandliner.Ateverytimestepduringthetransient

analysis, thecurrentvalueofN.(eitherzerofor'ift-off condition, oracompressive finitevalue)iscomputed.

Finally,thesupportrotational frictionspringsKRreflectanyrotational restraint thatmaybeofferedbythefoundation.

Thisspringrateiscalculated usingamodifiedBousinesq equationandisincludedtosimulatetheresistive momentofthesupporttocounteract rotationoftherackleginaverticalplane.Thisrotationspringisalsononlinear, withazerospringconstantvalueassignedafteracertainlimitingcondition ofslabmomentloadingisreached.Thenonlinearity ofthesesprings(friction elements9,11,13iand15inTable6.6.1)reflectstheedginglimitation imposedonthebaseoftheracksupportlegsandtheshiftsinthecentroidofloadapplication astherackrotates.Ifthiseffectisneglected, anysupportlegbending,inducedbyliner/baseplate frictionforces,isresistedbythelegactingasabeamcantilevered fromtherackbaseplate.

Thisleadstohigherpredicted loadsatthesupportleg-baseplate junctionthanifthemomentresisting capacityduetofloorelasticity atthefloorisincludedinthemodel.ThespringrateKS,modelingtheeffective compression stiffness ofthestructure inthevicinityofthesupport,iscomputedfromtheequation:

6-15 IIWII ThespringrateKS,modelingtheeffective compression stiffness ofthestructure inthevicinityofthesupport,iscomputedfromtheequation:

1111-+-+KSK1K2K3where:K1=springrateof,thesupportlegtreatedasatension-compression memberK2=localspringrateofpoolslabK3=springrateoffoldedplatecellstructure abovesupportlegAsdescribed inthepreceding section,therack,alongwiththebase,supports, andstoredfuelassemblies, ismodeledforthegeneralthree-dimensional (3-D)motionsimulation byatwenty-two degreeoffreedommodel.Tosimulatetheimpactandslidingphenomena

expected, upto64nonlinear gapelementsand16nonlinear frictionelementsareused.Gapandfrictionelements, withtheirconnectivity andpurpose,arealsopresented inTable6.6.1.Table6.6.2listsrepresentative valuesforamoduleusedinthesinglerackdynamicsimulations.

Forthe3-Dsimulation ofasinglerack,allsupportelements(described inTable6.6.1)areincludedinthemodel.Couplingbetweenthetwohorizontal seismicmotionsisprovidedbothbyanyoffsetofthefuelassemblygroupcentroidwhichcausestherotationoftheentirerackand/orbythepossibility oflift-offofoneormoresupportlegs.Thepotential existsfortheracktobesupported ononeormoresupportlegsduringanyinstantofacomplex3-Dseismicevent.'ll ofthesepotential eventsmaybe6-16 IIIIII simulated duringa3-Dmotionsothatamechanism existsinthemodeltosimulatetherealbehavior.

6.7'me'eat'onofthetonsoMoto6.7.1e-'stoAnasisUs'nuO'-DereeofFreedoRackModeHaving'assembled thestructural model,thedynamicequations ofmotioncorresponding toeachdegreeoffreedomarewrittenbyusingLagrange's Pormulation.

Thesystemkineticenergycanbeconstructed including contributions fromthesolidstructures andfromthetrappedandsurrounding fluid.Asinglerackismodelledindetail.Thesystemofequations canberepresented inmatrixnotationas:[Ml(q")-(Q)+(G)where:[M](q)totalmassmatrix;thenodaldisplacement vectorrelativetothepoolslabdisplacement; doubleprimestandsforsecondary derivations; avectordependent onthegivengroundacceleration; avectordependent onthespringforces(linearandnon-linear) andthecouplingbetweenmasses.Theequationcanberewritten as(q<<)~[M~1(Q)+[M)-1(G)Asnotedearlier,inthenumerical simulations runtoverifystructural integrity duringaseismicevent,therattlingfuelassemblies areassumedtomoveinphase.Thiswillprovidemaximumimpactforcelevel,andinduceadditional conservatism inthetime-history analysis.

6-17 I~\IIII Thisequationsetismassuncoupled, displacement coupledateachinstantintime,andisideallysuitedfornumerical solutionusingacentraldifference scheme.Theproprietary, USNRCaccepted, computerprogram"DYNARACK"*

isutilizedforthispurpose.Stressesinvariousportionsofthestructure arecomputedfromknownelementforcesateachinstantoftimeandthemaximumvalueofcriticalstressesovertheentiresimulation isreportedinsummaryformattheendof.eachrun.Insummary,dynamicanalysisoftypicalmulti-cell rackshasshownthatthemotionofthestructure iscapturedalmostcompletely bythebehaviorofatwenty-two degreeoffreedomstructure; therefore, inthisanalysismodel,themovementoftherackcross-section atanyheightisdescribed intermsoftherackdegreesoffreedom(ql(t),...q6(t) andq17-q22(t)).

Theremaining degreesoffreedomareassociated withhorizontal movements ofthefuelassemblymasses.In'thisdynamicmodel,fiverattlingmassesareusedtorepresent fuelassemblymovementinthehorizontal Thiscodehasbeenpreviously utilizedinlicensing ofsimilarracksforEnricoFermiUnit2(USNRCDocketNo.50-341),QuadCities1and2(USNRCDocketNos.50-254and265),RanchoSeco(USNRCDocketNo.50-312),OysterCreek(USNRCDocketNo.50-219),V.C.Summer(USNRCDocketNo.50-395),andDiabloCanyon1and2(USNRCDocketNos.50-275and50-323),St.LucieUnitI(USNRCDocketNo.50-335),ByronUnitsIandII(USNRCDocketNos.50-454,50-455),Vogtle2(USNRCDocket50-425),andMillstone Unit1(USNRCDocket50-245),IndianPointUnit2(USNRCDocketNo.50-247),amongothers.6-18 IIIlI plane.Therefore, thefinaldynamicmodelconsistsoftwelvedegreesoffreedomfortherackplustenadditional massdegreesoffreedomforthefiverattlingmasses.Thetotalityoffuelmassisincludedinthesimulation andisdistributed amongthefiverattlingmasses.6.7.2Evaluation ofPotential forInter-Rack ImactSinceracksareusuallycloselyspaced,thesimulation includesimpactspringstomodelthepotential forinter-rack impact.Toaccountforthispotential, yetstillretainthesimplicity ofsimulating onlyasinglerack,gapelementsarelocatedontherackatthetopandatthebaseplate level.Fig.6.5.2showsthelocationofthesegapelements.

Thebaseplate locationisadesignated potential impactregion,andtheimpactspringslocatedinthisregionareexpectedtoregisterimpactloads.However,theimpactisdisallowed inthecellularregionoftheracks.Therefore, theimpactspringslocatedatthetopmustnotindicateanyloadsatanytimeduringtheseismicevent.6.8Structural AccetanceCiteriaTherearetwosetsofcriteriatobesatisfied bytherackmodules:a0Kinematic Citer'oThis'riterion seekstoensurethattherackisaphysically stablestructure.

Theracksaredesignedtoprecludeinter-rack impactsinthecellularregion.Therefore, physicalstability oftherackisconsidered alongwiththecriterion thatinter-rack impactorrack-to-wallimpactsinthecellularregiondonotoccur.6-19 IlI b.StressLimitsThestresslimitsoftheASMECode,SectionIII,Subsection NFg1989Editionareused.Thefollowing loadingcombinations areapplicable (Ref.6.1.2)andareconsistent withtheplantUFSARcommitments.

LoadinCombinatio StressLim'tD+LD+L+ToD+L+To+LevelAservicelimitsD+L+Ta+ED+L+To+PfD+L+Ta+E'+L+FdLeveBservicematsLevelDservicelmxtsThefunctional capability ofthefuelracksshouldbedemonstrated.

Theabbreviations inthetableare'hoseusedinSection3.8.4oftheStandardReviewPlanandthe"ReviewandAcceptance ofSpentFuelStorageandHandlingApplications":

D=Deadweight-induced internalmoments(including fuelassemblyweight)L=LiveLoad(notapplicable for.thefuelrack,sincetherearenomovingobjectsintherackloadpath).FdForcecausedbytheaccidental dropoftheheaviestloadfromthemaximumpossibleheight.Pf~Upwardforceontherackscausedbypostulated stuckfuelassemblyE~Operating BasisEarthquake (OBE)E'DesignBasisEarthquake (DBE)6-20 IIIII Differential temperature inducedloads(normaloperating orshutdowncondition basedonthemostcriticaltransient orsteadystatecondition).

Ta~Differential temperature inducedloads(thehighesttemperature associated withthepostulated abnormaldesignconditions).

Theconditions TaandTocauselocalthermalstressestobeproduced.

Forfuelrackanalysis, onlyonescenarioneedbeexamined.

Theworstsituation willbeobtainedwhenanisolatedstoragelocationhasafuelassemblywhichisgenerating heatatthemaximumpostulated rate.Thesurrounding storagelocations areassumedtocontainnofuel.Theheatedwatermakesunobstructed contactwiththeinsideofthestoragewalls,therebyproducing themaximumpossibletemperature difference betweentheadjacentcells.Thesecondary stressesthusproducedarelimitedtothebodyoftherack;thatis,thesupportlegsdonotexperience thesecondary (thermal) stresses.

Forrackqualification, To,Taarethesame.6.9MaterialProertiesThedataonthephysicalproperties oftherackandsupportmaterials, obtainedfromtheASMEBoiler6PressureVesselCode,SectionZZZ,appendices, arelisted=in.Table6.9.1.Sincethemaximumpoolbulktemperature islessthan200F,thisisusedasthereference designtemperature forevaluation ofmaterialproperties.

6-21 IIIII 6.10StressLimitsforVariousConditions Thefollowing stresslimitsarederivedfromtheguidelines oftheASMECode,SectionIZZ,Subsection NF[6.1.2],inconjunction withthematerialproperties dataofthepreceding section.Allparameters andterminology areinaccordance withtheCode.6.10.1NoaandUsetCond't'ons LeveAorLe~elBa~Allowable stressintensiononanetsectionFt~0'Sy(Sy~yieldstressattemperature)

Ft=(0~6)(25I000)=15~000psi(rackmaterial)

Ft=isequivalent toprimarymembranestressesFt=(.6)(25,000)=15,000psi(upperpartofsupportfeet)(~6)(106/300)63@780psi(lowerpartofsupportfeet)b.Onthegrosssection,allowable stressinshearisoFv=.4Sy(.4)(25,000),10,000psi(mainrackbody)Ft=(.4)(25,000)=~10,000psi(upperpartofsupportfeet)(.4)(106,300)

~42,520psi(lowerpartofsupportfeet)6-22 IIIIIII c.Allowable stressincompressionI Fa.(kl)22[1--/2Ccr2SyF5klkl33E(-)+[3(-)/<<)-[(-)/8Cc3rrwhere:(2gz2E)1/2Syl=unsupported lengthofcomponent k~lengthcoefficient whichgivesinfluence ofboundaryconditions; e.g.kI1(simplesupportbothends)=1/2(cantilever beam)=2(clampedatbothends)E~Young'sModulusr=radiusofgyrationofcomponent kl/rforthemainrackbodyisbasedonthefullheightandcrosssectionofthehoneycomb region.Substituting numbers,weobtain,forbothsupportlegandhoneycomb region:Fa=15,000psi(mainrackbody)Fa~15,000psi(upperpartofsupportfeet)~63,780psi(lowerpartofsupportfeet)d0Maximumallowable bendingstressattheoutermost fiberduetoflexureaboutoneplaneofsymmetry:

Fb~0.60Sy=15,000Psi(rackbody)Fb~15,000psi(upperpartofsupportfeet)~63,780psi(lowerpartofsupportfeet)6-23 IIIIIII"n"II e.Combinedflexureandcompression:

faCmxfbxCmyfby++<1FaDxFbxDyFbywhere:faDirectcompressive stressinthesectionfbxMaximumflexuralaxisstressalongx-fbyMaximumflexuralaxisstressalongy-Cmy=0.85Dx1faF'exDy~112n2faF'eyF'exiey=kl23(-)x,yandthesubscripts x,yreflecttheparticular bendingplaneofinterest.

f.Combinedflexureandcompression (ortension):

fafbx+-+0.6SyFbxfby10Fby6-24 IIIII Theaboverequirement shouldbemetforboththedirecttensionorcompression case.6.'10.2LeveDServce'm'tsSectionF-1370(ASMESectionIII,AppendixF),statesthatthelimitsfortheLevelDcondition aretheminimumof1.2(Sy/Ft)or(0.7Su/Ft) timesthecorresponding limitsforLevelAcondition.

Suistheultimatetensile'stressat200'FperTable6.9.1.Since1.2Syisgreaterthan0.7Suforthelowerpartofthesupportfeet,thelimitis1.54forthelowersectionunderDBEconditions.

Thelimitfortheupperportionofthesupportfootis2.0underDBEconditions.

Insteadoftabulating theresultsofthedifferent stressesasdimensioned values,theyarepresented inadimensionless form.Thesedimensionless stressfactorsaredefinedastheratiooftheactualdeveloped stresstoitsspecified limitingvalue.Withthisdefinition, thelimitingvalueofeachstressfactoris1.0fortheOBEand2.0(or1.54)fortheDBEcondition.

6.11ResultsfortheAnalysisofSpentFuelRacksUsinaSinleRackModeland3-DSeismicMotionAcompletesynopsisoftheanalysisofthesinglerack,subjecttothepostulated earthquake motions,ispresented inasummaryTable6.11.1whichgivestheboundingvaluesofstressfactorsRi(il...7).Thestressfactorsaredefinedas:R1=Ratioofdirecttensileorcompressive stressonanetsectiontoitsallowable value(notesupportfeetonlysupportcompression)

R2Ratioofgrossshearonanetsectioninthex-direction toitsallowable value6-25 IIIIII R3R4Ratioofmaximumbendingstressduetobendingaboutthex-axistoitsallowable valueforthesectionRatioofmaximumbendingstressduetobendingaboutthey-axistoitsallowable valueR5R6R7Combinedflexureandcompressive factor(asdefinedin6.10.leabove)Combinedflexureandtension(orcompression) factor(asdefinedin6.10.1f)Ratioofgrossshearonanetsectioninthey-direction toitsallowable value.Asstatedbefore,theallowable valueofRi(i=1,2,3,4g5g6g7) is1fortheOBEcondition and2forteDBEexcetfothelowersectionofthesuortwherethefactoris1.54Thedynamicanalysisgivesthemaximax(maximumintimeandinspace)valuesofthestressfactorsatcriticallocations intherackmodule.Ualuesarealsoobtainedformaximumrackdisplacements andforcriticalimpactloads.Table6.11.1presentscriticalresultsforthestressfactors,andforrack-to-fuelimpactload.Table6.11.2presentsmaximumresultsforhorizontal displacements atthetopandbottomoftherackinthexandydirection.

Forsingleracksimulations "x"isalwaystheshortdirection oftherack.InTable6.11.2,foreachrun,boththemaximumvalueofthesumofallsupportfootloadings(4supports)aswellasthemaximumvalueonanysinglefootisreported.

Thetablealsogivesvaluesforthemaximumverticalloadandthecorresponding netshearforceatthelineratessentially thesametimeinstant,andforthemaximumnetshearloadandthecorresponding verticalforceatasupportfootatessentially thesametimeinstant.6-26 III Theresultspresented inTables6.11.1and6.11.2represent thetotalityofsinglerackrunscarriedout.Thecriticalcaseforstructural integrity calculations isincluded.

Displacements atthebaseplate levelareminimal.ThesinglerackanalysisforrunA04gavethehigheststressfactorsforsubsequent structural integrity calculations.

Subsequent tothedetailedanalysis, pedestals adjacenttothepoolwallswererelocated fromthecornercelltonewlocations 2cellsinboardfromtheedge.Sincethisrelocation couldaffecttheconclusions concerning rackstructural integiity, thecriticalcaseofrunA04wasre-considered usingthenewpedestallocations.

Theresultsofthatre-analysis arepresented inthetablesasrunA94.Thedetailedstructural integrity computations reportedhereinarebasedonthecriticalcasefortheloadingscenarioinvestigated.

Subsequent WholePoolMulti-Rack analysesarealsobasedonthefinalpedestallocations.

Theresultscorresponding toDBEgivethehighestloadfactors.ThecriticalloadfactorsreportedforthesupportfeetareallfortheuppersegmentofthefootforDBEsimulations andaretobecomparedwiththelimitingvalueof2'.Resultsforthelowerportionofthesupportfootarenotcriticalandarenotreportedinthetables.Analysesshowthatsignificant marginsofsafetyexistagainstlocaldeformation ofthefuelstoragecellduetorattlingimpactoffuelassemblies.

6-27 II Overturning hasalsobeenconsidered.

Thishasbeendonebyassumingamultiplier of1.5ontheDBEhorizontal earthquakes k(moreconservative thanrequiredbytheUSNRCStandardReviewPlan)andcheckingpredicted displacements.

Thehorizontal displacements donotgrowtosuchanextentastoimplyanypossibility foroverturning.

ItisnotedthattheanalysesoftheDonaldC.Cookplantfuelrackshaveincludedsomeasymetrically loadedracks.Theresultsofthesestudiescanbeusedasboundinganalysesforthecasewhenarackmoduleispickedupandrelocated whenloadedasymmetrically withfuelassemblies.

Theresultspresented hereinindicatethattwistingordeformation thatwouldcauselossoffunctionorviolation ofsafetymarginswillnotoccurduringaplannedrackrelocation.

6.12ImactAnalses6.12.1ImactLoadinBetweenFuelAssembandCeWallThelocalstressinacellwallisconservatively estimated fromthepeakimpactloadsobtainedfromthedynamicsimulations.

Plasticanalysisisusedtoobtainthelimitingimpactload.Thelimitloadiscalculated as3125lbs.percellwhichismuchgreaterthantheloadsobtainedfromanyofthesimulations.

6.12.2ImactsBetweenAd'acentRacksAllofthedynamicanalysesassume,conservatively, thattheracksareisolated.

However,thedisplacements obtainedfromthedynamicanalysesarelessthan50%oftherack-to-rack spacingorrack-to-wall spacingifthepoolisassumedfullypopulated.

6-28 l~I Therefore, weconcludethatnoimpactsbetweenracksorbetweenracksandwallsoccurduringtheDBEevent.ThishasbeenfurtherprovenbytheWholePoolMulti-Rack Analysisdiscussed inSection6'4.6.13WeldStressesCriticalweldlocations underseismicloadingareatthebottomoftherackatthebaseplate connection andattheweldsonthesupportlegs.Resultsfromthedynamicanalysisusingthesimulation codesaresurveyedandthemaximumloadingisusedtoqualifytheweldsontheselocations.

6.13.1BaselatetoRackWeldsandCell-to-Cell WeldsRef.[6.1.2](ASMECodeSectionIII,Subsection NF)theDBEcondition, anallowable weldstresst=.42psi.Basedontheworstcaseofallrunsreported/

weldstressforthebaseplate to'ackweldsis7605conditions.

permits,forSu29/820themaximumpsiforDBETheweldbetweenbaseplate andsupportlegischeckedusinglimitanalysistechniques.

Thestructural weldatthatlocationisconsidered safeiftheinteraction curvebetweennetforceandmomentissuchthataderivedfunctionofF/FyandM/Myisbelowalimitingvalueof1.0.6-29

,/

FyIMyarethelimitloadandmomentunderdirectloadonlyanddirectmomentonly.F,Maretheabsolutevaluesoftheactualforceandmomentsappliedtotheweldsection.Thecalculated valueis.637(1.0based'ntheinstantaneous peakloading.Thisvalueconservatively neglectsanygussetsinplacetoincreasepedestalareaandinertia.Thecriticalareathatmustbeconsidered forcell-to-cell weldsistheweldbetweenthecells.Thisweldisdiscontinuous asweproceedalongthecelllength.Stressesinthestoragecelltostoragecellweldsdevelopalongthelengthofeachstoragecellduetofuel'ssembly impactwiththecellwall.Thisoccursiffuelassemblies inadjacentcellsaremovingoutofphasewithoneanothersothatimpactloadsintwoadjacentcellsareinoppositedirections whichwouldtendtoseparatethechannelfromthecellattheweld.Thecriticalloadthatcanbetransferred inthisweldregionfortheDBEcondition iscalculated as5273lbs.ateveryfuelcellconnection toadjacent, cells.Anupperboundtotheloadrequiredtobetransferred is593lbs.Wherewehaveusedamaximumimpactloadof210lbs.(obtained fromTable6.11.1),wehaveassumedtwoimpactlocations aresupported byeachweldregion,andwehaveincreased theloadbyV'2toaccountfor3-Deffects.6.13.2HeatinofanIsolatedCellWeldstressesduetoheatingofanisolatedhotcellarealsocomputed.

Theassumption usedisthatasinglecellisheated,overitsentirelength,toatemperature abovethevalueassociated withallsurrounding cells.Nothermalgradientinthe6-30 IlL~~~~

verticaldirection isassumedsothattheresultsareconservative.

Usingthetemperatures associated withthisunit,analysisshowsthattheweldstressesalongtheentirecelllengthdonotexceedtheallowable valueforathermalloadingcondition.

Section7reportsthevalueforthisthermalstress.6.14WholePooMuti-RackWPMRAnals'sThesinglerack3-Dsimulations presented inthepreceding sectionsdemonstrate thestructural integrity, physicalstability, andkinematic compliance (norack-to-rack impactinthecellularregion)oftherackmodules.However,asnotedbefore,prescribing themotionoftheracksadjacenttothemodulebeinganalyzedintroduces anassumption ofunpredictable importinthesinglerackmodules.Forcloselyspacedracks,itispossibletodemonstrate kinematic compliance onlybymodelling allrackmodulesinonecomprehensive simulation whichisreferredtoasWholePoolMulti-Rack (WPMR)model.IntheWPMRanalysis, DBEseismicloadisapplied(Ref.6.1.3)-andallracksareassumedfullyloadedwithfuelassemblies.

Theprimaryintentoftheanalysisistoconfirmstructural integrity conclusions from3-Dsinglerackanalysisandtoensurethathydrodynamic effectsnotabletobemodelledinasinglerackanalysisdonotcauseunanticipated structural impacts.Thecrosscouplingeffectsduetothemovementoffluidfromoneinterstitial (inter-rack) spacetotheadjacentoneismodelledusingclassical potential flowtheoryandKelvin'scirculation theorem.Thisformulation hasbeenreviewedandapprovedbytheNuclearRegulatory Commission, duringthepost-licensing multi-rackanalysisforDiabloCanyonUnitIandIIreracking project.Thecouplingcoefficients arebasedonaconsistent modelling of6-31

thefluidflow.Whileupdatingofthefluidflowcoefficients, basedonthecurrentgap,ispermitted inthealgorithm, theanalyseshereareconservatively carriedoutusingtheconstantnominalgapsthatexistatthestartoftheseismicevent.Suchacomprehensive WPMRmodelwaspreparedfortheracksshowninthemodulelayoutdrawing(Fig.6.4.1).ComputercodeDYNARACKwasusedtoperformthesimulations.

Znordertoeliminate thelastsignificant elementofuncertainty inrackdynamicanalyses, thefrictioncoefficientwasalsoascribedtothesupportleg/poolbearingpadinterface inamannerconsistent withRabinowicz's experimental data[6.4.1].Asetoffrictioncoefficients weredeveloped byarandomnumbergenerator withGaussiannormaldistribution characteristics.

Theserandomderivedcoefficients areimposedoneachpedestalofeachrackinthepool.Theassignedvaluesarethenheldconstantduringtheentiresimulation inorderthattheresultsarereproducible.

6.14.1Multi-Rack ModelFigure6.14.1showsaplanformviewoftheDonaldC.'ookspentfuelpool.Arackandpedestalnumbering schemeissetupinthefigure.WesetupaglobalxaxistowardstheEast.Table6.14.1givesinformation onthenumberofcellsperrack,andontherackandfuelweights.Allracksareassumedloadedwithregularfuel.Therearetwenty-three racksinthepool.Thecaskareainthepoolismodelledasafictitious rack(Rackf24inFigure6.14.1).Asnotedpreviously, thepresenceofafluidmovinginthenarrowgapsbetweenracksandbetweenracksandpoolwallscausesfluidcouplingeffectswhichcannotbemodelledwithasimulation using6-32

onlyasinglerack.Verysimply,asingleracksimulation caneffectively includeonlythehydrodynamic effectsduetocontiguous rackswhenacertainsetofassumptions isusedforthemotionofcontiguous racks.Inamulti-rack analysisthefarfieldfluidcouplingeffectsofallracksisaccounted forusinganappropriate modelofthepool-rack fluidmechanics.

ForDonaldC.Cook,thecaskareawasmodelledassumingverylargefluidgapsbetweenracks18and24andbetweenracks23and24.IntheWholePoolMulti-Rack

analysis, usedtoinvestigate theinteraction effectsofallracks,weemployareduceddegree-of-freedom(RDOF)setforeachrackplusitscontained fuel.Thepurposeofthewholepooldynamicanalysis, including thecompletesetofracksinthepool,istodetermine whethereffects,notabletobeconsidered inasinglerackanalysis, alteranyoftheconclusions thatarebasedontheresultsofthe22DOFsinglerackanalysis.

Inparticular, themulti-rack analysisfocussesondisplacement excursions ofeachrackandonpedestalcompressive loads.TheWholePoolMulti-Rack analysisisalsoutilizedtoinvestigate thepossibility ofimpactsbetweenracksorbetweenracksandpoolwalls.Thereduceddegree-of-freedom structural modelforeachrackisdeveloped inasystematic waysothattheimportant kinematic resultsfromadynamicanalysisareinagreement withsimilarresultsfromasolutionobtainedusingthe22DOFsinglerackmodel.Theexternalhydrodynamic massduetothepresenceofwallsoradjacentracksiscomputedinamannerconsistentwithfundamental fluidmechanics principles andtheuseofareduced6-33 I

DOFfuelrackmodel[6.14.1].

Thefluidflowmodel,usedtoobtainthewholepoolhydrodynamic effectissitespecificandreflectsactualgapsandracklocations.

Thewholepoolmulti-rack modelincludesmanynon-linear compression onlygapelements.

'herearegapelementsrepresenting compression onlypedestals (normally fourpedestals areassumedforeachrack),gapelementsdescribing theimpactpotential ofthefuelassembly-fuel rackinterface, andgapelementstrackingrack-to-rack orrack-to-wall impactpotential at,thetopandbottomcornersoftherackcellstructure.

Znadditiontothecompression onlygapelements,,

eachpedestalhastwofrictionspringsassociated withthecompression spring.Asnotedpreviously, arandomnumbergenerator isusedtoestablish africtioncoefficient, foreachpedestalateachinstantwhenthepedestalisincontact,withtheliner.Theseismicexcitation directions XandYareshowninFigure6.14.1.ThecriticalDBEeventthatgovernsthebehaviorofthesinglerackanalysisisappliedtothe3-Dmulti-rack modelintheappropriate directions.

Threesimulations havebeencarriedoutusingcoefficients offrictionassumedtobe0.2,toberandomwithameanof0.5atallpedestals, andtobe0.8,respectively.

6.14.2--ResultsofMult'-Rack AnalsisTables6.14.2-6.14.4showthemaximumcornerabsolutedisplacements atboththetopandbottomofeachrackinxandydirections fromthreemulti-rack runs.ZnTable6.14.5,themaximumdisplacements obtainedfromthethreemulti-rack simulations arecomparedwithasinglerackanalysis.

Znallof6-34

~~5rl thesetables,theresultsforfuelrack24canbeignoredsinethereisnorealrackatthatLocation.

"Theabsolutedisplacement valuesarehigherthanthoseobtainedfromsinglerackanalysis.

Thus,itappearsessential toperformWholePoolMulti-Rack analysestoverifythatracksdonotimpactorhitthewall.Pigures6.14.2-6.14.5showthetimehistoryozrack-to-rack gapsforthecriticalracks.Ztisshownthattherack-to-rack dynamicgapsaregreaterthan1.65"duringa15secondearthcpxake.

Detailedexamination oftherack-to-rack dynamicgapsshowthattheracksprimar'ymovein-phaseinallthreesimulations.

Thatis,theentireassemblage ozrackstendstomoveandminimizechangesinrack-to-rack gaps.Table6.14.5alsopresentspeakpedestalcompressive loadsofallpedestals onthetwenty-three realracks.l:nadditiontoareportofmaximumpedestalloads,thetimehistoryofeachpedestalLoadforeachrackisarchivedforuseinthestructural evaluation ofthefuelpoolslaband,theenveloping wallsozthefuelpool,.Ztisnotedthatpredicted, maximumpedestalzorcefromthemulti-racksimulation givingtheLazgestpedestalload(RunMP3inTabLe6-14.5)islowerthantheresultobtainedfromsinglerackanalysis.

Themacimuminstantaneous verticalfootloadobtainedfromsinglerackanalysisis183300Lbs.PromtheWholePoolMulti-Rack RunMP3,wefindapeaksinglepedestalLoadoz180900lbs.Because,detailedrackstesscalculations arebasedonthesinglerackanalysisresults,zonewstructure concernsareidentified bythescopingWholePoolanalysisandtheoverallstructural integrity conclusions areconf~ed.6-35

6.15BearinPadAnalsisToprotect,theslabfromhighlocalized dynamicloadings, bearingpadsareplacedbetweenthepedestalbaseandtheslab.Fuelrackpedestals impactonthesebearingpadsduringaseismiceventandtheverticalpedestalloadingistransferred totheliner.Thebearingpaddimensions aresettoensurethattheaveragepressureimpactedtotheslabsurfaceduetoastaticloadplusadynamicimpactloaddoesnotexceedtheAmericanConcreteInstitute

[6.15.1]limitonbearingpressures.

Thetimehistoryresultsfromthedynamicsimulations foreachpedestalareusedtogenerateappropriate staticanddynamicpedestalloadswhichareusedtodevelopthebearingpadsize.Fromthewholepoolmulti-rack

analysis, theworstcaseloadingonapedestal(instantaneous peakload)is183,300lbs.(seeTable6.14.5).Fora12"x12"pad,thisgivesanaverageinstanteous pressurepa=1273psi.Section10.15of[6.15F1]givesthedesignbearingstrengthasfb=P(.85fc')CwhereP~.7andfcŽ3500psiforDonaldC.Cook.6=1exceptwhenthesupporting surfaceiswideronallsidesthantheloadedarea.Inthatcase,C~(A2/A1)'butnotmorethan2.A1istheactualloadedarea,andA2isanareagreaterthanA1whichisdefinedpictorially intheACIcommentary onSection10.15.ForDonaldC.Cook,1~6~2;ifweconservatively use6=1,thenfb2083psiwhichisinexcessofthecalculated pressurepa.Thus,significant marginisprovidedbythebearingpads.6-36 I

References forSection6USNRCStandardReviewPlan,NUREG-0800 (1981).ASMEBoiler&PressureVesselCode,SectionIII,Subsection NF,appendices (1989).USNRCRegulatory

.Guide1.29,"SeismicDesignClassification,"

Rev.3,1978.HoltecProprietary Report-Verification andUser'sManual,ReportHI-89364, January,1990."Friction Coefficients ofWaterLubricated Stainless SteelsforaSpentFuelRackFacility,"

Prof.ErnestRabinowicz, MIT,areportforBostonEdisonCompany,1976.USNRCRegulatory Guide1.92,"Combining ModalResponses andSpatialComponents inSeismicResponseAnalysis,"

Rev.1,February, 1976."TheComponent ElementMethodinDynamicswithApplication toEarthquake andVehicleEngineeringg S.LevyandJ.P.D.Wilkinson, McGrawHill,1976."Dynamics ofStructures,"

R.W.CloughandJ.PenziengMcGrawHill(1975).HoltecProprietary Reports:User'sManual,ReportHI-89343,Revision0;Theory,ReportsHI-87162, Revision1,andHI-90439, Revision0;Verification, ReportHI-87161,Revision2."DynamicCouplinginaCloselySpacedTwo-BodySystemVibrating inLiquidMedium:TheCaseofFuelRacks,"K.P.SinghandA.I.Soler,3rdInternational Conference onNuclearPowerSafety,Keswick,England,May1982.R.J.Fritz,"TheEffectsofLiquidsontheDynamicMotionsofImmersedSolids,"JournalofEngineering forIndustry, Trans.oftheASME,February1972,pp167-172.USNRCRegulatory Guide1.61,"DampingValuesforSeismicDesignofNuclearPowerPlants,"1973.6-37 I

"FluidCouplinginFuelRacks:Correlation ofTheoryandExperiment",

byB.Paul,HoltecReportHI-88243.

ACI318-89,ACI318R-89,BuildingCodeRequirements forReinforced

Concrete, AmericanConcreteInstituteg Detroit,Michigan, 1989.6<<38 II~~4'4IlI Table6.3.1CORRELATION COEFFICIENT TimeHistoGrouN-S"andE-W(1,2)N-StoVertical(1,3)E-WtoVertical(2,3)DBB0.01460.12690.01016OBE0.10560.09560.10606-39

Table6.5.1DEGREESOFFREEDOMLocation(Node)Dz.spacementUxUyUzRotationexeyezPlP2P3P17P18P19q4q5q6q20q21q22.where:Point2isassumedattachedtorigidrackatthetopmostpo'int.P7P8P9P10P11P12P13P14P15P16Pi'qi(t)+U1(t)qi(t)+U2(t)qi(t)+U3(t)i~1,7,9,11,13,15,17 i~2,8,10,12g14I16g18 i~3,19Ui(t)arethe3knownearthquake displacements.

6-40 IIIIIOlI Table6.6.1NUMBERING SYSTEMFORGAPELEMENTSANDFRICTIONELEMENTSZ.Nonlinear SinsGaEements(64Total)NumberNodeLocatioDescr'ion SupportS1SupportS2SupportS3SupportS42I2Zcompression Zcompression Zcompression Zcompression Xrack/fuel elementonlyelementonlyelementonlyelementonlyelementassemblyimpact2I2X'rack/fuel assemblyimpactelement2I2Yrack/fuelassemblyimpactelement212Yrack/fuelassemblyimpactelement9-24Otherrattlingmassesfornodes1*i3*i4*and5*2544Bottomcross-sectionofrack(aroundedge)Inter-rack Inter-rack Inter-rack Inter-rack Inter-rack Inter-rack Inter-rack impactimpactimpactimpactimpactimpactimpactelementselementselementselementselementselementselementsInter-rack impactelements4564Topcross-section ofrack(aroundedge)Inter-rack Inter-rack Inter-rack Inter-rack Inter-rack Inter-rack-"

Inter-rack Inter-rack impactimpactimpactimpactimpactimpactimpactimpactelementselementselementselementselementselementselementselements6-41 II Table6.6.1(continued)

NUMBERING SYSTEMFORGAPELEMENTSANDFRICTIONELEMENTSII.Fr'ctionElements(16total)Number123'4~5678910111213141516NodeLocat'onSupportS1SupportSlSupportS2SupportS2Support.S3SupportS3SupportS4SupportS4SlS1S2S2S3S3S4S4DescritionXdirection frictionYdirection frictionXdirection frictionYdirection frictionXdirection frictionYdirection frictionXdirection frictionYdirection frictionXSlabmoment,YSlabmomentXSlabmomentYSlabmomentXSlabmomentYSlabmomentXSlabmomentYSlabmoment6-42 IIlI Table6.6.2TYPICALINPUTDATAFORRACKANALYSES(lb-inchunits)SupportFootSpringConstantKs(0/in.)Frictional SpringConstantKf(0/in.)RacktoFuelAssemblyImpactSpringConstant(0/in.)ElasticShearSpringforRack(4/in-)ElasticBendingSpringforRack(0-in/in.)

ElasticExtensional Spring(5/in.)ElasticTorsional Spring(g-in./in.)

IGaps(in.)(forhydrodynamic calculations) 4.91x1061.837x1091.38x105(x-direction) 1.61x10(y-direction) 5.986x10(x-direction) 4.866x10(y-direction) 5.458x10(x-zplane)4.71x1010(y-zplane)4.074x1071.322x1096-43 IIII Table6.9.1RACKMATERIALDATA(200'F)Material304S.S.Young'sModulusE(psi)27.9x106YieldStrengthSy(psi)25000UltimateStrengthSu(psi)71000SectionIXIReference TableX-6.0TableI-2.2TableX-3.2SUPPORTMATERXALDATA(200F)Material1SA-240,Type304(upperpartofsupportfeet)27.9x106Psi.25,000PSi71000PSi2SA-564-630 (agehardenedat1100'F)279x106PSl106,300140,000PSiPSl6-44 IIk Table6.11.1STRESSFACTORSANDRACK-TO-FUEL IMPACTLOADRunRemarks-1RRack/Fuel ImpactLoadPerCellatWorstLocationAlongHeightCriticalLocation~lbs-2R-3R-5R-TRa03DBEp=o2182cellsloadedwithreg.fuela04DBEp=o8182cellsloadedwithreg.fuela30p=0.291cellsloadedwithreg.fuela32p=0.291cellsloadedwithreg.fuel180.2179.6190209.8~018.274.018.284.012.181.012.176.023.074.025.079.012.046.011.049.159.167.172.214.090.118.094~112.166.161.178.172.073.106.090.110.198.417.204.431.109.281.109.271~231.442.239.460.127.299.127.289.027*.078*.033.095.013.052.015.049a94Sameasa04174.8withreloca-tedpedestals

.018.325.018.056.168.250~121.118.187.483.219.522.032.113*Uppervaluesareforrackcellcross-section justabovebaseplate.

Lowervaluesareforsupportfootfemalecross-section justbelowattachment tobaseplate.

IIIIiIII Table6.11.2RackDisplacements andSupportLoads(allloadsareinlbs.)FLOORLOAD(sumofallsupportfeet)inarack~lbs.a03Fullload3.510x10p=0'DBE,Reg.FuelMAXIMUMVERTICALLOAD(1foot)~lbs.1.549x10MAXIMUMSHEARLOADANDCOINCIDENT VERTICALLOAD30212(1.511x10

)DX~in.~0609.0084DY**~in..0562.0105a04Fullload3.510x10p=0.8~DBE,Reg.Fuel1.605x1035832(9.791x10

).0679.0015.0583.0012a30HalfloadinPos.xp=0.2DBE,Reg.Fuela32HalfloadinPos.yp=0'DBE,Reg.Fuel1.883x101.883x101.021x109.973x1020108(1.005x10

)19389(9.71x10

).0520.0010.0482.0055.0450.0008.0515.0080a94Sameasa043.508x10withreloca-pedestals 1.833x1044406(1.4829x10).0678.0014.0778.0018Thevalueinparenthesis istheverticalloadattheinstatwhentheshearloadismaximum.Themaximumverticalandshearloadsgenerally donotoccuratthesameinstant.Uppervaluesaretopmovements; lowervaluesarebaseplate movements (notnecessarily atthesametime).

III Table6.14.1RACKNUMBERING ANDWEIGHTINFORMATION RackNo.123456789101112131415161718192021222324*No.of~Ces1821681681821821821561441441561561561431321321431431431821681681661200Weightof2570023700237002570025700257002250020900209002250022500'2250020800193001930020800208002080025700237002370023900177000WeightofFuelAssemblb.155015501550155015501550155015501550155015501550155015501550155015501550155015501550155015500fictitious 6-47 III Table6.14.2MAXIMUMDISPLACEMENTS FROMWPMRRUNMP1(Friction Coefficient

=0.2)rack123567891011121314151617181920212223uxt.7004E-01

.7506E-01

.8464E-01

.5943E-01

.5131E-01

.6793E-01

.4783E-01

.4856E-Ol

.4533E-01

.3830E-01

.4224E-01

.6411E-01

.7253E-01

.4602E-01

.3557E-01

~3467E-01.5755E-Ol

.1011E+00

~6980E-01.8202E-01

.8404E-01

.8173E-01

,.5647E-01 uyt.7756E-01

.5227E-01

.7521E-01

~5218E-01.5306E-01

.9512E-01

.8928E-01

.7065E-01

.6377E-01

.5754E-01

.5336E-01

.9620E-01

.1079E+00

.1114E+00

.1079E+00

~9211E-01.4429E-01

.1301E+00

~1125E+00.8680E-01 1455E+00.1057E+00

.6598E-01 uxb.6235E-01

.6494E-01

.6897E-01

.4960E-01

.4290E-01

.5135E-01

.3978E-01

.3607E-01

.3196E-01

.2848E-01

..3659E-01

.4885E-01

.6568E-01

.3650E-01

.2634E-01

~2817E-01.5326E-01

.8596E-01

~6341E-01.6878E-01

~6800E-01.7111E-'01

~4812E-01uyb.7303E-01

.3936E-01

.6619E-01

.3597E-01

.4496E-01

.9095E-01

.7830E-01

.5917E-01

.5192E-01

.4354E-01

.4329E-01

.8429E-01

.9505E-01

.9847E-01

.9325E-01

.8608E-01

.3140E-01

.9693E-01

.8575E-01

.6048E-01

.1229E+00

.9050E-01

.6156E-01 uxt=absolute valuex-direction atuyt=absolute valuey-direction atuxb=absolute valuex-direction atuyb=absolute valuey-direction atofmaximumrackracktop;ofmaximumrackracktop;ofmaximumrackrackbaseplate; ofmaximumrackrackbaseplate.

cornerdisplacement incornerdisplacement incornerdisplacement, incornerdisplacement in6-48 IIIII Table6.14.3MAXIMUMDISPLACEMENTS FROMWPMRRUNMP2'(RandomFrictionCoefficient) rackuxtuyt'uxbuyb12345678910111213~14151617181920212223.6524E-01

.1423E+00

.1247E+00

.1860E+00

.1106E+00

.9642E-01

.4742E-01

.1801E+00

.1275E+00

.2336E+00

.1710E+00

.4015E-Ol

.1088E+00

.1439E+00

.6218E-01

.3322E+00

.1727E+00

.1269E+00

.8411E-01

~8402E-01.1280E+00 8427E-01.2389E+00

.4772E-01

.5829E-01

.4122E-01

.6628E-01

.6379E-Ol

.7250E-01

.6267E-01

.5755E-01

.3974E-01

.7640E-01

.8644E-01

.4740E-01

.1034E+00

.4029E-01

.5620E-01

.5413E-01

.5385E-01

.1958E+00

.8106E-01

.6480E-01

.4742E-01

.4951E-01

.6471E-01

.3373E-01

.1442E+00

.1161E+00

.1859E+00

.1091E+00

.8330E-01

.3334E-01

.1819E+00

.1207E+00

.2336E+00

.1712E+00

.2869E-01

.1030E+00

.1282E+00

.6029E-01

.3374E+00

.1727E+00

.1223E+00

.6365E-01

.5976E-01

.1281E+00

.7430E-01

.2388E+00

.2303E-01

~4598E-01.2566E-01

.3161E-01

.2673E-01

.6348E-01

.5443E-01

.4534E-01

.2115E-01

.5527E-01

.6245E-01

.2678E-01

.1040E+00

.1865E-01

.3386E-01

.3677E-01

.4896E-01

.1913E+00

.7508E-01

.4419E-01

.3530E-01

.2335E-01

.5758E-01 uxt=absolute valuex-direction atuyt=absolute valuey-direction atuxb=absolute valuex-direction atuyb=absolute valuey-direction atofmaximumrackracktop;ofmaximumrackracktop;ofmaximumrackrackbaseplate; ofmaximumrackrackbaseplate.

cornerdisplacement incornerdisplacement incornerdisplacement incornerdisplacement in6-49 IIII rackTable6.14.4MAXXMUMDZSPLACEMENTS FROMWPMRRUNMP3(Friction Coefficient=0.8}

uxtuytuxbuyb1234567891011121314151617181920212223.2035E+00

.2751E+00

.2637E+00

.1363E+00

.1333E+00

.1720E+00

.2425E+00

.1785E+00

.1519E+00

.8112E-01

.1146E+00

.1005E+00

.1604E+00

.7786E-01

.8616E-01

.9843E-01

.8975E-01

.1418E+00

.1959E+00

.2741E+00

.2117E+00

.2361E+00

.1016E+00

.1702E+00

.5173E-01

.5740E-01

.5449E-01

.8237E-01

.1514E+00

.8747E-01

.6039E-01

.4434E;01

.5007E-01

.7975E-01

.1602E+00

.1310E+00

.7618E-01

~5521E-01~4/80E-01.7115E-01

~4416E+00.1720E+00

.5563E-01

.5159E-01

.6081E-01

.7703E-01

.1987E+00

-2732E+00

-2638E+00

.1321E+00 1273E+00.1609E+00

.2461E+00

.1784E+00

.1506E+00

.7887E-01

.1117E+00

~9143E-01.1633E+00

.7823E-01

.8214E-01

.1024E+00

.9063E-01

.1089E+00

.1922E+00

.2727E+00

.2120E+00

.2242E+00

.1033E+00

.1774E+00.1658E-01

.4010E-01

.2788E-01

.6876E-01

.1617E+00

.8782E-01

.4260E-01

.3129E-01

.2883E-01

.5071E-01

.1601E+00

.1073E+00

.5953E-01

.3148E-01

.2903E-01

.7056E-01

.4526E+00

.1806E+00

.3118E-01

-2287E-01

.3986E-01

.7364E-01 uxt=absolute valuex-direction atuyt=absolute valuey-direction atuxb=absolute valuex-direction atuyb=absolute valuey-direction atofmaximumrackracktop;ofmaximumrackracktop;ofmaximumrackrackbaseplate; ofmaximumrackrackbaseplate.

cornerdisplacement incornerdisplacement incornerdisplacement incornerdisplacement in6-50 II Table6.14.5MAXIMUMRACKDISPLACEMENT ANDFOOTLOADRuna94RemarksSingleRackAnalysisWPMR,p~0.2MaximumRackCornerDisplacement inch0.07780.1455(Rack$21iny)MaximumFootPedestalForcelbs.183,300157,400(Rack$19,Foot4)WPMR,Randomp0.3322(Racki16inx)170,900(Rack$19IFoot4)WPMR,p=0'0.4416(Rack$18iny)180,900(Rack$5,Foot2)pfrictioncoefficient 6-51 II TYPICALCELLWALLSBASEPLATE BASEPLATE BEARINGPADFigure6.2.1Pictorial ViewofRackStructure 6-52 III 0.200.10RQ-0.00LdLaJC3C3-0.10l'lI>III-O.-100100300500700TIME*0.0lsec.900110013001500FIGURE6.3.lDOE-t~-SACCELERATION TIME-flISTORY I~~~~I 0.200.10-O.00LdLdC3C3-0.10-0-'1OO10030050070090TIME*0.01sec.110013001500FIGURE6.3.2DBEE-WACCELERATION TIMEHISTORY II 0.200.10o-0.00UlC3-0.10-O.-100100300500700900110013001500TIME*0.0lsec.FIGURE6.3.3DBE-VERTICALACCELERATION TIMEHISTORY r~(~~l 0.8003O.60eOI-CL0.40C3~0.20O.10FREQUENCY, IIz10FIGURE6.3.4HORIZONTAI'.

DESIGNSPECTRUMANDN-STIMEHISTORYSPECTRUM(5%damping)

~~i~~I4 0.80-~0.60IoI-~0.40LLIC3C30.200.10FREQUENCY, Hz10FIGURE6.3..5HORIZOtlTAI',

DESIGNSPECTRUMANDE-WTIMEHISTORYSPECTRUM(5%,damping)

~~~~~~~~I~L~~I O.600.40COLLIC3~0.200.10FREQUENCY,Hz10Figure6.3.6VERTICALDESIGNANDTINEHISTORYDERIVEDSPECTRA(5>damping)

I 0.08.oi0.03ChIZ,LJI~~-O.02LLJC3C3-007-O.-10010030050070090011001300TIME*0.01sec.1500FIGORE6.3.7OBE-N-'CCELERATION TIMEHISTORY I

0.08cri0.03ChOw~-0.02LLJ-0.07-O.-100100300500700900TI&1E*G.Olsec.110013001500FIGURE6.3.8OBE-E-NACCELERATION TINEHISTORY 14 0.05-0.05100300500700900110013001500TItlE*0.0lsec.FIGURE6.3.9OBE-VERTICALACCELERATION TIMEHISTORY

0.60FREQUENCY, Hz10Figure6.3.10HORIZONTAL DESIGNSPECTRUMANDTIMEHISTORYDERIVEDN-SSPECTRUM(2%damping) l 0.60Cf)C3~"0.40ICtLdLd~0.200.10FRE(FLUENCY, Hz10Figure6.3.llHORIZONTAL DESIGNSPECTRUMANDE-WTIMEHISTORY'S DERIVEDSPECTRUM(2%damping)

I O.500.40(/)0.30C)~0.20LLI0.10cnpFREQUENCY, Hz10Figure6.3.12VERTICALDESIGNANDTIMEHISTORYDERIVEDSPECTRA(2%damping)

B,ackGeometric Centerline PieH/qpizp,YLongDirection Supportf'IP16PsTypicalFrictionElementFigure6.5.lSCHEMATXC MODELFORDYNARACK6-65

!)

TypicalTopImpactElement0IIIRackStructure TypicalBottomImpactElementFigure6.5.2RACK-TO-RACK IMPACTSPRINGS6-66 I

~CFLLWALLxstt>~~~KIFU"='SS:-!)'=LY!C"='

IMPACTh."-RlNGIYsFIGURE6.5.3IMPACTSPRINGARRANGEMENT ATNODEi6-67 lI 1720LFigure6.5.4DEGREESOFPREEDOHHODELLXHG RACKHOTXON I

L2FIGURE6.5.5RACKDEGREESOFFREEDOMFORX-ZPLANEBENDING6-69 II 18L2L2FIGURE6.5.6RACKDEGREESOFFREEDOMFORY-ZPLANEBENDING6-70 llI FiJELASSY/C-->>

llFACT'SPRINGy,~I0.25HPJ2XEz::c<,C.G.P2%gH/2T'PIC):Pi~aT.'iGEL<S~0.25MFRCTZO.'fIHxrZZ.-:C"-

SPRZ,'tG, Kfs>>.o."-zt:-"S?REYG,.KFOUNDATION ROTATIONAL CRK.EAt>C-SPREiVG,KFIGURE6.6.12-DVIEWOFRACKMODULE6-71 II 2RACK6321RACK521RACK42RACK12342RACKll421RACK1021RACK16421RACK1732RACK16RACK24(NOTREAL)21RACK2321RACK22421RACK~2RACK9212RACK15RACK2134321RACK221RACK12RACK82RACK72'IRACK1421RACKIS21RACK2042RACK194FIGURE6.14.lRACKANDFOOTPEDESDALNUMBERING FORD.C.COOKMULTI-RACK MODEL6-72 IIlll 2.03-2.00COOKPOOLMULTI-RACK SEISMICANALYSIS, RUNMP2(RandomCof.)RACK16TORACK17NORTHCORNERDYNAMICGAPATRACKTOP1.98x'195o1.93CI1.90OD1881.851.831.80012345678910111213141516TIME,SEC.FIGURE6.14.2 II 2.032.00COOKPOOLMULTI-RACK SEISMICANALYSIS, RUNMP2(RandomCof.)RACK16TORACK17SOUTHCORNERDYNAMICGAPATRACKTOP1.9819591.93zO1.90O~o188I1.851.831.80012345678910111213141516TIME,SEC.FIGURE6.14.3 l'IILt~lili 2.052.00COOKPOOLMULTI-RACK SEISMICANALYSIS, RUNMP3(Cof.=O.S)

RACK12TORACK18WESTCORNERDYNAMICGAPATRACKTOP1.95-1.90u1.851.80o17I1.701.651.60012345678910111213141516TIME.SEC.FIGURE6.14.4 IIIIIIIIIII 2.052.00COOKPOOLMULTI-RACK SEISMICANALYSIS, RUNMP3(Cof.=O.S)

RACK12TORACK18EASTCORNERDYNAMICGAPATRACKTOP1.95xO190~1.85D1.80C3o1.751.701.651.60012345678910111213141516TIME,SEC.FIGURE6.14.5 III

7.0 CCIDENTANALYSISANDMISCELLANEOUS

STRUCTURAL EVALUATIONS 7.1Introduction Thissectionprovidesresultsofaccidentanalysesperformed todemonstrate regulatory compliance ofthenewfuelracks.Thereareseveraltypesofaccidents whichcouldpotentially affectthespentfuelstoragepool.Installation oftheproposedhighdensityrackswillenablethestorageofincreased amountsofspentfuelintheDonaldC.Cookspentfuelpool.Accordingly, accidents involving thespentfuelpoolhavebeenevaluated toensurethattheproposedspentfuelpoolmodification doesnotchangethepresentdegreeofassurance topublichealthandsafety.Thefollowing accidents andmiscellaneous structural evaluations havebeenconsidered:

Refueling accident-DroppedFuelLocalCellWallBucklingAnalysisofWeldedJointsduetoIsolatedHotCellCraneUpliftLoad7~2efuelinAccidents Thissectionconsiders three(3)accidents associated withthehandlingoffuelassemblies.

7~2~1DroedFuelAssemblTheconsequences ofdroppinganeworspentfuelassemblyasitisbeingmovedoverstoredfuelisdiscussed below.a~DoedFueAssembAcc'dentAfuelassemblyisdroppedfrom36"abovethetopofastoragelocationandimpactsthebaseofthemodule.Localfailureofthebaseplate isacceptable; however,therackdesignshouldensurethatgrossstructural failuredoesnotoccurandthesubcriticality oftheadjacentfuelassemblies isnotviolated.

Calculated 7-1 IIIIII b.resultsshowthattherewillbenochangeinthespacingbetweencells.Localdeformation ofthebaseplate intheneighborhood oftheimpactwilloccur,butthedroppedassemblywillbecontained andnotimpacttheliner.Weshowthatthemaximummovementofthebaseplate towardthelineraftertheimpactislessthan1.52".Theloadtransmitted tothelinerthroughthesupportbysuchanaccidentiswellbelowthatcausedbyseismicloads.DroaedFuelAssemblAccidentllOnefuelassemblyis(assumeddryweight.=1550lbs.)droppedfrom36"abovethetopoftherackandimpactsthetopoftherack.Thisisamoreseverecondition thanthecurrently postulated dropof1616lbs.fromaheightof15"abovethetopoftherack.Permanent deformation oftherackisacceptable, butisrequiredtobelimitedtothetopregionsuchthattherackcross-sectional geometryatthelevelofthetopoftheactivefuel(andbelow)isnotaltered.Analysisshowsthatalthoughlocaldeformation occurs,itisconfinedtoaregionabovetheactivefuelarea.Theregionofpermanent deformation istoadepth5.34"below.thetopoftherack.C~DroaaedFuelAssemblyAccidentXIX.Thispostulated accidentisidentical to(b)aboveexceptthatthefuelassemblyisassumedtodropinaninclinedmannerontopoftherack.Analysesshowthatthestraightdropcase(casebabove)boundstheresults.7.3LocalBuckl'nofFuelCelWallsThissubsection andthenextonepresentsdetailsonthesecondary stressesproducedbybucklingandbytemperature effects.Theallowable localbuckling'tresses inthefuelcellwallsareobtainedbyusingclassical platebucklinganalysis.Thefollowing formulaforthecriticalstresshasbeenusedbasedonawidthofcell"b":(SeeFigure7.3.1.)pn2Et212b2(1-p2)7-2 III whereE=27.9x10psi,p~0.3,(Poison's ratio),t~075gb=8.75".Thefactorpissuggested in(Ref.7.3.1)tobe4.0foralongpanel.Forthegiven'data crcr~7411psiItshouldbenotedthatthisstability calculation isbasedontheappliedstressbeinguniformalongtheentirelengthofthecellwall.-Intheactualfuelrack,thecompressive stresscomesfromconsideration ofoverallbendingoftherackstructures duringaseismiceventandassuchisnegligible attheracktopandmaximumattherackbottom.Itisconservative toapplytheaboveequationtotherackcellwallifwecomparecrcrwiththemaximumcompressive stressanywhereinthecellwall.AsshowninSection6,thelocalbucklingstresslimitof7411psiisnotviolatedanywhereinthebodyoftherackmodules,sincethemaximumcompressive stressintheoutermost cellisa3585psi.(FromTable6.11.1forR6~.239,thestressatthebaseoftherackundercombineddirectplusbendingloadsiscr~R6xallowable stress).7.4AnalsisoWeldedJointsinRackduetoIsolatedHotCellInthissubsection, in-rackweldedjointsareexaminedundertheloadingconditions arisingfromthermaleffectsduetoanisolatedhotcell.Athermalgradientbetweencellswilldevelopwhenanisolatedstoragelocationcontainsafuelassemblyemittingmaximumpostulated heat,whilethesurrounding locations areempty.Wecanobtainaconservative estimateofweldstressesalongthelengthofanisolatedhotcellbyconsidering abeamstrip(acellwall)uniformly heatedandrestrained fromgrowthalongonelong7~3 IIIIII

'Iedge.Thestripissubjecttoauniformtemperature risehT59.66F.Thetemperature risehasbeencalculated fromthedifference ofthemaximumlocalwatertemperature andbulkwatertemperature inthespentfuelpool.(seeTables5.5.1and5.7.1).Then,usingashearbeamtheory,wecancalculate anestimateofthemaximumvalueoftheaverageshearstressinthestrip(seeFigure7.4.1).Thefinalresultforwallmaximumshearstress,underconservative restraint assumptions isgivenasrmax=tEaT.931wherea=9.5x106in/in'FTherefore,

'weobtainanestimateofmaximumweldshearstressinanisolatedhotcellas16984'Sincethisisasecondary thermalstress,itisappropriate tocomparethistotheallowable weldshearstressforafaultedeventr<.42Su=29820psi.Inthefuelrack,thismaximumstressoccursnearthetopoftherackanddoesnotinteractwithanyothercriticalstress.7.5CraneUliftLoadof3000lb.Alocalupliftloadof3000lb.(UFSARlimitis2950lb.)willnotinduceanyupliftstressesintherackwhicharemoreseverethanthelimitingconditions discussed intheforegoing.

Thischoiceofloadshouldbeanupperboundloadonthemaximumloadthatcanbeappliedtoastruckfuelassemblyduringremoval.7-4 IIIlIt~-I 7.6References forSection77.3.1"Strength ofMaterials",

S.P.Timoshenko, 3rdEdition,PartIZ,pp194-197(1956).7-5 I

-)cf,abFIGURE7~3.1LOADINGONRACKWALLHeatedCellWallKAWdF&WWW&WWWA'W eldLine'FIGURE7.4.1VfELDEDJOINTINRACK'-6 I

8'STATICANDDYNAMICANALYSISOFFUELPOOLSTRUCTURE 8.1IntoductionTheDonaldC.Cookspentfuelpoolisasafetyrelated,seismiccategoryI,reinforced concretestructure.

Inthissectionanabstractoftheanalysistodemonstrate thestructural adequacyofthepoolstructure ispresented.

Theobjectoftheanalysisistodemonstrate thecompliance ofthepoolslabandconfining wallstotheapplicable designcodesandtoNRCregulations forthecondition ofincreased loadingsduetohighdensityfuelstorage.Theloadingonthepoolstructure isproducedbythefollowing discretecomponents:

a)StaticLoad'n1)Deadweightofpoolstructure pluspoolwater(including hydraulic pressureonthepoolwalls).2)Deadweightoftherackmodulesandfuelassemblies storedtherein.b).DnamicLoadin1)Verticalloadstransmitted bytheracksupportpedestals totheslabduringaDBEorOBEevent.2)Inertialoadsduetotheslab,poolwallsandcontained watermasswhichariseduringaDBEorOBEevent.c)ealLoad'n1)Meantemperature riseandtemperature gradientacrossthepoolslabandthepoolwallsduetotemperature differential betweenthepool,waterandtheatmosphere externaltotheslabandwalls.8-1 II Thespentfuelpoolisanalyzedusingthefiniteelementmethod.Theresultsfortheaboveloadcomponents arecombinedusingfactoredloadcombinations mandatedbyNUREG-0800, theStandardReviewPlan(SRP),Section3.8.4(Ref.8.1.1).Itisdemonstrated thatforthecriticalfactoredloadcombinations, structural integrity ismaintained whenthefuelpoolisassumedtobefullyloadedwithhighdensityfuelrackswithallstoragelocations occupiedbyfuelassemblies.

ThegeneralpurposefiniteelementcodeANSYS(Ref.8.1.2)isutilizedtoperformtheanalysis.

Thecriticalregionsexaminedarethefuelpoolslabandthemostcriticalwallsectionsadjoining thepoolslab.Bothmomentandshearcapacities ofthecriticalregionsarecheckedforstructural integrity.

Alsoevaluated islocalpunchingintegrity inthevicinityofafuelrackbearingpad.Structural capacityevaluations arecarriedoutinaccordance withtherequirements oftheAmericanConcreteInstitute (ACI)(Refs.8.1.3and8.1.4).Inthisanalysis, theloadfactorsofSRPSection3.8.4havebeenusedtogetherwiththeallowable concreteandreinforcement loadsascalledforbytheAmericanConcreteInstitute.

Thisconstitutes themostconservative approachtothestructural qualification ofthepoolstructure basedonastaticloadqualification method.8.2GenealFeaturesotheModeThefuelpoolmodelisconstructed usinginformation fromdesignbasisDonaldC.Cookauxiliary buildingstructural drawings.

Adescription oftheportionofthepoolmodelledforanalysisisgiveninthefollowing.

8-2 II~~~I~IL~~~

Thefuelpoolslabisa5'-21/2"thickreinforced concreteslabwithinsidedimensions 39'-19/16"wideand58'-31/8"long.Theslabislocatedatelevation 600'-605'-2 1/2"anditslongdirection isalignedalongtheplantEast-West direction.

TheEastedgeoftheslabhasa5'-2"thickverticalreinforced wallwhichextendsabovetheslabandismodeledtolevel650'.TheWestedgeoftheslabhasa6'hickwallfromlevel,605'-2 1/2"tolevel650'.TheWestwallseparates thefuelpoolfromthefueltransfercanalwhichisnotmodelled; however,thediscontinuity inthewallstructure inthecenteroftheWestwallisincluded.

Allwallmodelingisdonetolevel650',andweassumefreeedgesatthislevel.TheNorthwallisa6'hickwallextending fromtheslabtolevel650'.TheSouthedgeoftheslabhasa5'hickwallextending uptolevel650'.Itisclearfromtheabovedescription thattheSouthwallhasthelargestlengthtothickness ratio,andtherefore, mayrepresent alimitingcondition ofstructural strength.

Thefoundation matisatelevation 584'ndthepoolslabandupperwallsaresupported onthefoundation matbywallsandcolumnsaroundtheperiphery.

TheNorthedgeoftheslabissupported byacontinuous 3'-0"thickwall,whiletheEastedgeispartially supported alongitslengthbya2'-6"thickwall.TherearethreeverticalcolumnslocatedattheSoutheast andSouthwest corneroftheslab,andintermediate alongtheSouthedge;ThereisalsoaportionofawallbelowtheSouthedgeatonelocation.

Thefloorslabhasinteriorverticalsupportprovidedbya2'-0"thick'erticalwallproviding verticalrestraint inboththeNorth-South andEast-West direction overasubstantial lengthofslab.Inaddition, thereisa25'panstandardW14x158wideflangebeamfromtheslabNorthedgesupporting walltogiveadditional poolslabsupport.ThisproppedbeamisskewedtowardtheEast16'romtheNorthedge.8-3 lI Theentirebeam(thestraightpartplustheskewedpart)issupported vertically byfourTS10"x10"squaretubes.Eachtubularcolumn,hasalsobeenstiffened byfour8"x3/8"plates.Figure8.2.1showsaschematic oftheabovegeometry.

Thepoolslabisassumedtobeloadedwith23highdensityfuelrackshavingatotalof3616cells.Foranalysispurposes, eachcellisassumedtocontaina1550lb.weightfuelassembly.

Asnotedpreviously, all,fuelpoolwallsabovethepoolslabareassumedtohaveafreeedgeatlevel650'.Lateralrestraint isprovidedtotheverticalwallsatcertainlocations abovethe605'evel.

Thisrestraint simulates theeffectofadjacentstructure whichisnotincludedinthemodelledenvelope.

Figures8.2.2and8.2.3showlayoutsoftheentire3-Dfiniteelementmodel.Thegridworkindifferent regionsshowsthetotalityofelementsused.Shellelementsareusedtomodeltheslabandwalls,whilebeamelementsareusedtomodelthecolumns.Thefiniteelementmodelisconstructed usingtheANSYSclassical shellelementSTIF63andthebeamelementSTIF44oftheANSYSfiniteelementcode.Theshellelementthickness inthevariousregionsofthestructure istheactualthickness ofthestructure atthelocation.

Thefiniteelementmodelispreparedfortheanalysisofbothmechanical loadandthermalload.Theeffectsofthereinforced concrete(crackedoruncracked) areaccounted forinthefiniteelementmodelbyestablishing anappropriate effective modulusforeachshellelementandeffective inertiasforthecolumnelements.

Effective moduliaredefinedforeachlocalin-planeaxisfortheshellelements.

Thedifferent modulireflectthefactthatdifferent reinforcement geometries maybeusedinperpendicular directions oftheplate-like sectionswhen8-4 I!~I thedifferent concretesectionassumptions (crackedoruncracked) areappliedtotheslabandwalls.Onlymajorreinforcement whichaffectstheplateandshell-like behaviorofthestructure isincorporated intothedefinition oftheeffective moduli;additional, localreinforcement invariousareasofthepoolstructure areneglected inthedefiningoftheeffective moduli.However,suchlocalreinforcement isaccounted forinthestrengthevaluation afterresultsareobtained.

Thenon-homogeneous natureofthereinforcement istakenintoaccountbydefiningdifferent materialtypesasnecessary toreflectthevaryingvaluesofeffective moduliindifferent regions.Theconcretesectionassumptions (crackedoruncracked) arefullyinaccordance withthe'equirements ofAmericanConcreteInstitute (Refs.8.1.3and8.1.4).Inaccordance withRef.8.1.4,weassumeuncracked sectionproperties forthemechanical loadanalyses(including loadfactors).

Forthethermalanalyses, itisshownthatthethermalgradients willalwaysyieldacrackedsectioniftheuncracked stiffness isused;therefore, aniterative solutionisusedtoshowthatcrackedsectionproperties shouldbeusedforthethermalanalyses.

Theeffective properties fortheelementsusedinthefiniteelementmodelarecalculated usingstandardprocedures forreinforced concretesectionstodefineequivalent effective homogeneous materials havingtheappropriate stiffness andstrength.

8-5 l

8.3LoadinConditions Znordertoevaluatetheresponseduetothedifferent loadmechanisms outlinedinSection8.1,thefollowing finiteelementanalysesarecarriedout.Sixloadingcasesaredefinedbelowwhichenableustoobtainthemomentsandshearsforfactoredloadingsbylinearcombination.

1.Deadloadingfromconcrete, reinforcement and40'fhydrostatic head.Theloadingisappliedasa1.0gverticalgravitational loadforthestructure andasurfacepressureontheslabandwallsforthehydrostatic head.2.Deadloadingduetoweightsofrackplusfullfuelload.Theseloadsareappliedasauniformstaticpressureappliedtotheslab.3.Seismicverticalloadingduetoracksplusfuelloadappliedasaneffective sustained pressureonthefloorslabpedestals.

Theloadingappliedisobtainedfromthe'-Dwholepoolmulti-rack analysisdescribed inSection6ofthisreport.Fromtheresultsofthatanalysis, we.takethestoredtimehistoryofeachpedestalloadanddefineaneffective sustained poolpressureloadwhichyieldsthesametotalimpulseoverthetimedurationoftheseismicevent.Thedetailsofdeveloping thiseffective sustained pressureloadarepresented later.Wedevelopeffective sustained verticalpressureloadsforbothOBEandDBEeventsandthenperformappropriate finiteelementanalyses.

4~Seismichorizontal loadingduetostructure weight(including reinforcement).

Theloadingisappliedasa1ghorizontal andverticalacceleration appliedtothestructure plusahydrodynamic pressureequivalent toanacceleration ofallofthewatermassagainsttheweakestwall.Theacceleration levelisobtainedfromtheapplicable responsespectraandistakenasthepeakglevelonthespectraatfrequencies abovethelowestnaturalfrequency forthestructure.

AseparateANSYSfrequency analysissimulation iscarriedouttoestablish thedynamiccharacteristics ofthestructure.

'8-6 IIerI Seismichorizontal loadduetoshearloadsfromeachofthepedestals.

Thisloadingisobtainedbyusingthestatic+effective dynamicloadsdeveloped forcase3aboveandassumingacoefficient offriction=.8.Thedirection oftheseloadsissetsoastodevelopstressesthatmaximizetheloadcombinations necessary tosatisfystructural integrity requirements discussed below.Znthisloadcasewealsoimposealateralpressureontheweakestpoolwalltosimulatehydrodynamic effectsfromfluidcouplingduetorackmotionrelativetothewall.6.Ameantemperature riseplusathermalgradientisappliedacrossthewallsandfloorslabtosimulatetheheatingeffectofthewaterinthepool.Thisgradientiscalculated basedonthemaximumwalltemperature deducedfromthepoolbulktemperature calculations forthelicensing basisscenarios presented inSection5ofthisreport.Forsubsequent discussion ofstructural integrity checksusingvariousmandatedloadcombinations, werefertotheaboveindividual finiteelementloadcasesas"case1-6",respectively.

Asnotedabove,inadditiontothestaticanalysesusingthedeveloped finiteelementmodel,wealsoperformafrequencyanalysisofthepoolstructure assumingthatallcontained fluidisattachedtothepoolslab.Uncracked sectionproperties areusedhere.Thisfrequency analysisisusedtodetermine thelowestpoolstructural frequencies soastoestablish appropriate seismicamplifiers toapplytoloadcases1and4.Theseseismic8-7 lII amplifiers areobtainedfromtheresponsespectraoftheseismiceventandmultiplytheresultsofloadcases1and4whenformingthemandatedloadcombinations.

Asnotedabove,thecase3loadinginvolvesthedetermination ofaneffective pressureloadtorepresent theseismicloadontheslabduetotheracksplusfuel.Themethodofdetermination ofthiseffective pressureisdescribed below.Asnotedpreviously, theHoltec3<<Ddynamicsimulation codeDYNARACKisusedtosimulatetheseismicresponseoftheentirefuelpoolcontaining multipleracks.Theverticalloadtimehistoryfromeachpedestaloneachrackissavedinanarchivalfile.Forthepoolslabstructural

analysis, whichisbasedonstaticanalyses, wecomputeaneffective staticloadincrement basedonaveraging ofthetimehistory.Figure8.3.1isusedtoillustrate theconceptwherethetotalpedestalloadisconsidered asthestaticload(FsinFigure8.3.1plusatimevaryingcomponent).

NotethatinFigure8.3.1azeroloadduringaportionofthetimemeansthatthepedestalhasliftedoff.Wedefineaneffective staticloadforthepurposesofpoolstaticanalysisandstructural qualification asfollows:a0b.C~Promthearchivalpedestalloadtimehistorywemay,ateachpointintime,determine thetotalpoolloadFTbysummingthetotalloadsforeachpedestal.

Ateachpointintimei,wecandefinethedynamicloadincrement forthepoolasFT-FS=DFiwhereFSnowrepresents thetotalstaticloadontheslab.WekeeptrackofthenumberoftimepointsiwhereDFi)0.Anequivalent.

staticpoolload(seismicaddertothestaticpoolload)isdefinedasSEISMICADDERSUMDFI/SUMNIi 8-8

whereSUMDFZisthesumofallofthenonzeroDF1andSUMNiisthetotalnumberofpointsinthetimehistorywherethedynamicpoolloadincrement isgreaterthanzero.d~Znformingtheappropriate loadcombinations mandatedforstructural integrity checks,thecalculated "seismicadder"dividedbythepoolarea,isusedastheeffective seismicpressureontheslab.Ofallloadingconditions mandatedinRef.8.1.1,thefactoredloadswhichapplytothisstructure andaredeemedcriticalare:A.1'D+1'EB.~75(1.4D+1.9E+1.7To)CDD+E'Towhere:D~DeadloadE'DesignBasisEarthquake (DBE)E~Operating BasisEarthquake (OBE)To=SteadyStateThermalLoadTheappropriate loadcasesareformedfromtheindividual finiteelementanalysesasfollows:D~case1+case2E'DBEamplifier xcase1+DBEamplifier xcase4+case3(forDBE)+case5(forDBE)E~OBEamplifier xcase1+OBEamplifier

+case4+case3(forOBE)+case5(forOBE)Tocase6Loadcombinations areformedusingabsolutevalueswherenecessary soastomaximizecriticalstressresultants.

8-9 II Asnotedabove,foranalysisoffuelpoolstructural integrity, theseismicamplifiers arebasedonthepeakglevelresponses atthelowestresonantfrequency thatareobtainedfromtheplantacceleration responsespectrum.

Weshowthatthisisconservative.

8.4ResultsoAalsesTheANSYSpostprocessing capability isusedtoformtheappropriate loadcombinations identified aboveandtoestablish thecriticalbendingmomentsinvarioussectionsofthepoolstructure.

Theultimatemomentsforeachsectionarecomputedusingallowable limitstrengthlevelsasdescribed inRef.8.1.3.ForDonaldC.Cook,thefollowing limitstrengths forconcreteandforreinforcement areusedinthecomputation oflimit(ultimate) moments.concreteo'c~3500psi(compression) reinforcement

~cry~40000psi(tension/compression)

Zneachsection,wedefinethesafetymarginforbendingastheultimatebendingmomentdividedbythecalculated bendingmoment(fromtheANSYSpostprocessing oftherequiredloadcases).Table8.4~1summarizes theresultsobtainedfromthefiniteelementanalysesandshowsminimumsafetymarginsoneachsectionofthestructure.

Notethatthesearesafetymarginsbasedonthefactoredloadconditions asmandatedinRef.8.1.1andneedonlysatisfyalimit~1.0.8-10 Il Thefloorslabperimeter isalsocheckedagainstgrossshearfailureunderfactoredloadconditions.

Localbearingstrengthandpunchingshearcalculations areperformed inaccordance with(Reft8.1.3)~Thepoollinerissubjecttoin-planestrainsduetomovementoftheracksupportfeetduringtheseismicevent.Calculations aremadetoestablish thatthelinerwillnotfailduetocyclicstraining causedbytherackfootloading.AnANSYSanalysisofalinerplatesectionsubjected toverticalandhorizontal staticpedestalloadingiscarriedout.Thetimehistoryresultforthepedestalloadingisthenusedtoevaluatethenumberofstresscyclestobeexpectedinthelinerforeachevent.Thecumulative damagefactor(CDF)iscomputedandshowntobelessthan1.0incriticalregionsofthelinerandattachment locations.

The@umberofstresscycles'sed intheCDFevaluation isbasedon1DBEand20OBEevents.Criticalregionsaffectedbyloadingthefuelpoolcompletely withhighdensityracksareexaminedforstructural integrity underbendingandshearingaction.Itisdetermined thatadequatesafetyfactorsexist.assumingthatallracksarefullyloadedwithnormal(unconsolidated) fuelandthatthefactoredloadcombinations are'hecked againsttheappropriate structural designstrengths.

Itisalsoshownthatlocalfrictional loadingonthelinerresultsinin-planestressesthatarelowenoughsothatlinerfatigueisnotaconcern.8-11 aI 8.7References foSection88.F18.1.28.1.3F1.4NUREG-0800/

SRPforReviewofSafetyAnalysisReportsforNuclearPowerPlants,Section3.8.4,July1981.ANSYSUser'sManual,SwansonAnalysisRev.4.3,1987.ACI318-89,ACI318R-89,BuildingCodeRequirements forReinforced

Concrete, AmericanConcreteInstitute, Detroit,Michigan.

ACI349.1R-80, Reinforced ConcreteDesignforThermalEffectsonNuclear.PowerPlantStructures, 1981.8>>12 IIIIII Table8.4.1SAFETYFACTORSFORBENDINGOFPOOLSTRUCTURE REGIONSREGIONFACTOROFSAFETYSlabNorthWallEastWallSouthWallWestWall1.231.081.261.05Thefactorsofsafetyhavebeenobtainedusingconservative assumptions onmechanical andthermalloaddistribution.

Theyrepresent factorsofsafetyoverthevaluesrequiredbyNUREG-0800.

8-13 III EASTWALLNORALLSOUTALLIII~rrr~rrretWESTWALL~err~IrrrrrrrrrI~~I~Irt.~~~~~~~III~s~rrt~~rsr'~I~~~~~~rt~~I~srt~~aeseeespasoSesptag IV~~I~rr~~~r~~~r~,SrII~~~~sIIII~~~I~~~~~~~I~~Irrtr~r>r~r~~II~I~I~~~~~~I~I~~~~rFIGURE8.2.1ISOMETRIC VIEWOFCOOKSPENTFUELPOOL8-14 IIIIIII FIGURE8.2.2OVERALLFINITEMODELOFCOOKPOOLTOPVIEN8-15 III FIGURE8.2.3OVERALLFINITEMODELOFCOOKPOOLBOTTOMVIEN8-16 IIII FIGURE8.3.1PEDESTALLOADVS.TIME(Positive LoadMeansPedestalinContactwithLiner)8-l7 II

9.0 RADIOLOGICAL

EVALUATION 9.1FuelHandlinAccident9.1.1AssumtionsandSourceTermCalculations Anevaluation oftheconsequences ofafuelhandlingaccidenthasbeenmadeforfuelof5.0wt4initial-enrichment burnedto60,000MWD/MTUgwiththereactorconservatively assumedtohavebeenoperating at3411MWthermalpower(38.8MWD/KgUspecificpower)priortoreactorshutdown.

Exceptforthefuelenrichment anddischarge burnup,theassumptions usedintheevaluation arethesameasthosepreviously reviewedandacceptedbytheUSNRC.Asr,,inthe,previousevaluation, thefuelhandlingaccidentwasconservatively assumedtoresultinthereleaseofthegaseousfissionproductscontained inthefuel-rodgapsofalltherodsinthepeak-power fuelassemblyatthetimeoftheaccident.

Gapinventories offissionproductsavailable forreleasewereestimated usingboththeassumptions identified inRegulatory Guide1.25+andthoseinNUREG/CR-5009().

NUREG/CR-5009

"'hasconfirmed thattheRegGuide1.25assumptions remainconservative forextendedburnupexceptforI-131,forwhichthereleasefractionwasreportedtobe20%higher.Mostofthegaseousfissionproductshavingasignificant impactontheoff-sitedosesaretheshort-lived nuclidesofIodineandXenonwhichreachsaturation inventori'es duringin-coreoperation.

Theseinventories dependprimarily onthefuelspecificpoweroverthefewmonthsimmediately preceding reactorshutdown.

Inthehighestpowerassembly, thespecificpowerandhencetheinventory ofIodineandXenonwillbedirectlyrelatedtothepeakingfactor(assumedtobe1.65perReg.Guide1.25).9-1 I1lII Theinventory oflong-lived Kr-85(10.73yearhalf-life),

however,isnearlyproportional totheaccumulated fueldischarge burnupandhenceisindependent ofthepeakingfactor.BecauseKr-85isaweakbetaemitter,ithasonlyaminorimpactonoff-sitedoses,primarily affecting thewhole-body betadose.Theoff-siteradiological consequences aredominated bytheshort-lived radionuclides (whichareatsaturation concentration independent offuelburnup).Inthepresentanalysis, thecalculated dosesarehigherandmorecoservative thanthoseofthepreviousevaluation because(1)theanalysesreportedhereusehighergapinventories basedonRegGuide1.25assumptions and(2)theuseoftheup-datedORIGEN-2code<>forcalculating thefissionproductinventories.

Resultsoftheevaluation confirmthattheoff-sitedosesremainwithintheregulatory limits.Thepresentevaluation usesvaluesforthe2-houratmospheric dispersion factor(X/Q)andfilterefficiencies thathavepreviously beenreviewedandaccepted.

Coreinventories offissionproductswereestimated withtheORIGEN-2codebaseduponareactorpowerof3411MWtandfuelwithaninitialenrichment of5.0:U-235burnedto60,000NWD/MTU.Calculations weremadefor100hourscoolingtimeasthesourcetermforthefuelhandlingaccident.

Thereleasefractionofthecoreinventories assumedtobeinthegapbyboththeRegGuide1.25andNUREG/CR5009 assumptions arelistedinTable9.1.Thefollowing

equation, from-RegGuide1.25,wasusedtocalculate thethyroiddose(D)fromtheinhalation ofradioiodine, D=ZFgI;FPBR;(x/Q)

DFpDFgRadssummedoverallIodineradionuclides.

9-2.

~~~I~~~I FSfractionoffuelrodIodineinventory ingapspacecoreIodineradio-nu-clideinventory attimeoftheaccident(cu-ries)fractionofcoredam-agedsoastoreleaseIodineintherodgap(1/193)Breathing rate=3.47x10cubicmeterspersecondDoseconversion factor(rads/curie) fromReg.Guide1.25(X/Q)=atmospheric diffusion factor(3.15x10sec/m)Corepeakingfactor(1.65)DF<=effective Iodinedecontamination factorforfilters(=10)DFp=effective Iodinedecontamination factorforpoolwater(=150)Thegapinventories listedinTable9-1aretheproductofI;(coreinventory) andFz(thefractionexistinginthegap).Thefunctionusedtocalculate theexternalwholebodydosefrombeta(D,)orgamma(D<)radiation inthecloudusesmanyofthetermsdefinedaboveandisgivenby:D~=Z0.23(x/Q)FPG<E~andDfZ0~25(X/Q)FPGiEwhereG<isthegapinventory ofthegaseousradionuclides ofXeandKrandthefunctions abovearesummedoverallthenoblegases.E>andE<aretheaverageenergiesofdecay(betaandgammaradiation respectively) forthevariousradionuclides.

Thesefunctions assumethenoblegasdecontamination factorsinwaterandthecharcoalfiltersare1.0.Thegapinventories ofradioiodine 9-3 C~l~~~I makeanegligible contribution tothewholebodydoses,D~orD<,becauseofthelargedecontamination factorsappropriate totheiodines.9.1.2ResultsAsummaryoftheassumptions usedtoevaluatethefuelhandlingaccidentisgiveninTable9-2.Theminimumtimeaftershutdownwhenfuelassemblies wouldbemovedwasconservatively assumedtobe100hoursasidentified intheTechnical Specifications.

At100hoursaftershutdown, thetwo-hourdoseatthesiteboundary, forafuelhandlingaccidentreleasing allofthegaseousfissionproductradioactivity inthegapsofallrodsinthehighestpowerassembly, areasfollows:Two-HourSiteBoundarDoseNUREG/CR-5009 MethodReg.GuidePrevious1.25A~nalsisInhalation thyroiddose=7.07RadsWholebodybetadose,Dp=0.36RadsWholebodygammadose,D<=0.31Rads5.97Rads0.70Rads0.58Rads2.150.51Thesedosesarewellwithinthelimitsof10CFRPart100inconformance withtheacceptance criteriaofSRP15.7.4.(Rev.1,July1981)9-4

9.2SolidRadwasteThenecessity forresinreplacement isdetermined primarily bytherequirement forwaterclarityandtheresinisnormallychangedaboutonceayear.Nosignificant increaseinthevolumeofsolidradioactive wastesisexpectedwiththeexpandedstoragecapacity.

Duringreracking operations, acertainamountofadditional resinsmaybegenerated bythepoolcleanupsystemonaone-timebasis(perhaps10to30cubicfeet).,9.3GaseousReleasesGaseousreleasesfromthefuelstorageareaoftheauxiliary buildingarecombinedwithotherplantexhausts.

Normally, thecontribution fromthefuelstorageareaoftheauxiliary buildingisnegligible comparedtotheotherreleasesandnosignificant increases areexpectedasaresultoftheexpandedstoragecapacity.

9.4Personnel ExosuresDuringnormaloperations, personnel workinginthefuelstorageareamaybeexposedtoradiation fromthespentfuelpool.Operating experience hasshownthatthearearadiation doserates,whichoriginate primarily fromradionuclides inthepoolwater,aregenerally lessthan1mrem/hrbutmaytemporarily increaseto2.5-3mrem/hrduringrefueling operations.

Noevidencehasbeenobservedofanycruddeposition aroundtheedgesofthepoolthatmightcauselocalareasofhighradiation.

9-5

Radiation levelsinzonessurrounding thepoolarenotexpectedtobesignificantly affected.

Existingshielding aroundthepool(waterdepthandconcretewalls)providemorethanadequateprotec-tion,despitetheslightlycloserapproachtothewallsofthepool+Typicalconcentrations ofradionuclides inthepoolwaterareshowninTable9.3.Duringfuelreloadoperations, theconcentrations willincreasedue.tocruddepositsspallingfromspentfuelassemblies andtoactivities carriedintothepoolfromtheprimarysystem.Whiletheseeffectsmayincreasetheconcentrations (asmuchasafactorof10),thepoolcleanupsystemsoonreducestheconcentrations tothenormaloperating range.Noevidencehasbeenseenofanysignificantly higherradiation dosesneartheedgeofthepoolthatmightsuggesttheaccumulation ofcruddeposits.

Operating experience hasshownthattherehavebeennegligible concentrations ofairborneradioactivity andnoincreases areexpectedasaresultoftheexpandedstoragecapacity.

Areamonitorsforairborneactivities areavailable intheimmediate vicinityofthespentfuelpool.Noincreaseinradiation exposuretooperating personnel isexpectedand,therefore neitherthecurrenthealthphysicsprogramnortheareamonitoring systemsneedtobemodified.

9.5AnticiatedEosureDurinRerackinTotaloccupational exposureforthereracking operation isestimated tobebetween6and11person-rem, asindicated inTable9.4.Whileindividual taskeffortsandexposures maydifferfromthoseinTable9.4,thetotalisbelievedtobeareasonable estimateforplanningpurposes.

Diverswillbenecessary toremove9-6 l1,J~.

certainunderwater appurtenances.

Theseappurtenances arewellremovedforthestoredfuelwhichminimizes theradiation doseratetothedivers.Carefulmonitoring andadherence topre-prepared procedures willassurethattheradiation dosetothediverswillbemaintained ALARA.Allofthereracking operation willutilizedetailedprocedures preparedwithfullconsideration ofALARAprinciples.

Similaroperations havebeenperformed inanumberoffacilities inthepastandthereiseveryreasontobelievethatreracking canbesafelyandefficiently accomplished attheDonaldC.CookNuclearPlant,withminimumradiation exposuretopersonnel.

Theexistingradiation protection programattheCookNuclearPlantisadequateforthereracking operations.

Wherethereisapotential forsignificant airborneactivity, continuous airsamplerswillbeinoperation.

Personnel wearprotective clothingand,ifnecessary, respiratory protective equipment.

Activities aregovernedbyaRadiation WorkPermitandpersonnel monitoring equipment willbeassignedtoeachindividual.

Asaminimum,thisincludesthermoluminescent dosimeters andpocketdosimeters.

~Additional personnel monitoring equipment (i.e.,extremity badgesoralarmingdosimeters maybeutilizedasrequired.

Work,personnel traffic,andthemovementofequipment willbemonitored andcontrolled tominimizecontamination andtoassurethatexposures aremaintained ALARA.Inreracking, theexistingstoragerackswillberemoved,decon-taminated asmuchaspossiblebywashingandwipe-downs, packagedandshippedtoalicensedprocessing/disposal facility.

Shippingcontainers andprocedures willconformtoFederalDOTregulations andtherequirements ofanyStateDOTofficethroughwhichtheshipmentmaypass.9-7

9.6References forSection9Reg.Guide1.25(AECSafetyGuide25),"Assumptions usedforevaluating thepotential radiological consequences ofafuelhandlingaccidentinthefuelhandlingandstoragefacilityforboilingandpressurized waterreactors".

2~C.E.Beyer,etal.,"Assessment oftheUseofExtendedBurnupFuelinLightWaterPowerReactors",

NUREG/CR-5009, PacificNorthwest Laboratory (PNL-6258).

3.A.G.Croff,"AUser'sManualfortheORIGEN2ComputerCode",ORNL/TM-7175, July1980(ORIGEN=ORNLIsotopeGeneration andDepletion)

Section15.7.4,"Radiological Consequences ofFuelHandlingAccidents" NUREG-0800, Section15.7.4,Rev.1July19819-8 III Table9-1INVENTORIES ANDCONSTANTS OFSIGNIFICANT FISSIONPRODUCTRADIONUCLIDES NUCLIDESHUTDOWNCOREINVENTORY CURIESDECAYCONST.X,1/HRS100hrs100hrsTOTALGAPINVENTORY, CURIESNUREG/CR-5009 Reg.Guide1.25DOSECONVERSION RiE(MEV)PE(MEV)7l-131l-1329.0E+71.3B.83.591E-33.013E-17.5E+6Negligible

~6.3E+6Negligible 1.48E+65.35E+40.1860.389I-1331.8E+83.332E-26.3B56.3B540E+50.4190.597I-134I-1351.9E+81.7E+87.905E-11.048E-1Negligible Negligible Negligible Negligible 2.5E+41.24E+50.3941.456Kr-85MKr-85Kr-87Kr-881.9E+71.4E+63.6E+75.0E+71.547E-17.376E-65.451E-12.442E-1Negligible 2.0E+5Negligible Negligible Negligible 4.2E+5Negligible Negligible 0.2510.002Xe-131MXe-133MXe-133Xe-1351.0E+65.6E+61.8E+83.9E+72.427E-31.319E-25.506E-37.626E-27.9E+41.5E+55.1E+6Negligible 7.9E+41.5E+51.0E+7Negligible 0.1630.2330.1020.0810.3090.262'ORELEASEFRACTIONGIVEN-ASSUMEDSAMEASREG.GUIDE1.25 II Table9.2DATAANDASSUMPTIONS FORTHEEVALUATION OFTHEFUELHANDLINGACCIDENTSourceTermAssumtionsVALUESCorepowerlevel,MWTFuelburnup,MHD/MTUAnalytical methodReleaseAssumtions341160,000ORIGENNumberoffailedfuelrodsFractionofcoreinventory releasedtogap(NUREG/CR-5009 releaseofIodine-131 isreportedtobe20%higher)AssumedpowerpeakingfactorInventory ingapavailable forreleasePooldecontamination factorsallrodsin1of193assemblies Re.Guide1.254oftheIodine-104oftheXenon-104ofKr-85301.65Table9.1ForIodinesFornoblegasesFilterdecontamination factorsForIodinesFornoblegasesAtmospheric Dispersion, (x/Q)Breathing rate15011013.15x10sec/m3.47x10m/sec9-10 IlI Table9.3TypicalConcentrations ofRadionuclides intheSpentFuelPoolWaterConcentration NuclideAg-110MCo-58Co-60Cs-134Cs-137~C;~ml4.6x101'x104.4x103.2x106.4x109-11 I-II Table9.4PRELIMINARY ESTIMATEOFPERSON-REM EXPOSURES DURINGRERACKING

~SteNumberofPersonnel HoursEstimated Exosure<>RemoveemptyracksWashandDeconracksCleanandVacuumPoolRemoveunderwater appurtences Partialinstallation ofnewrackmodules401025200.5to1.00.08to0.20.3to0.60.4to0.80.25to0.5MovefueltonewracksRemoveremaining racksWashandDeconracks150120300.8to1.51.5to3.00.2to0.4Installremaining newrackmodulesPrepareoldracksforshipment35800.4to0.81.0to2.0<'iTotalExposure, person-rem 6to12Assumesminimumdoserateof21/2mR/hr(expected) toamaximumof5mR/hr,exceptforpoolvacuuming operations whichassumes4to8mR/hranddivingoperations whichassume20to40mR/hr.Maximumexpectedexposure, althoughdetailsofpreparation andpackaging ofoldracksforshipmenthavenotyetbeendeter-mined.9-12 lI 10.0IN-SERVICE SURVEILLANCE PROGRAM10.1~PuroseThissectiondescribes theprogrammatic commitments madebyIndianaMichiganPowerCompany(I&M)forin-service surveillance oftheBoralneutronabsorption materialtocomplywiththeprovisions ofSectionIV(8)oftheOTPositionPaper(Ref.10.1.1).Allmaterialusedwithinastoragesystemforspentnuclearfuelarequalified toalevelofperformance predicated uponcalculated worstcaseenvironmental conditions andarebasedonaccelerated testingofthematerials tolevelsofservicelifecorresponding tothatenvironment.

Becausesuchenvironmental compatibility testinginthelaboratory conditions isaccelerated, itisprudentthateachofthesystemcomponents bemonitored tosomeextentthroughout theservicelifetoassurethattheactualin-service performance remainswithinacceptable parameters asdefinedbytheaccelerated testing.Formanyofthematerials, monitoring throughout theservicelifeisrelatively easy,however,theneutronabsorbing materialisencasedinastainless steeljacketprecluding adirectvisualorphysicalexamination duringthein-servicecondition.

Thecouponsurveillance programpresented hereinisintendedtoprovideadefinitive assessment ofthepresentphysicalintegrity oftheneutronabsorber',

aswellasinferential information todetectfuturedegradation.

10-1 i

Thecouponsurveillance procedure consistsofpreparing twelveneutronabsorbercouponscarefully, encasedinastainless steelmetaljacket,andsuspending themfroma"coupontree".Thecoupontreeisplacedinthecenterofagroupoffreshlydischarged fuelassemblies eachtimeanewbatchisdischarged tothepool.Thegroupofassemblies surrounding thecoupontreeshallbethosewhichhavetheabove-average valuesofradialpeakingfactor.Theobject,ofcourse,istosubjectthis"tree"tothemaximumradiation exposureinthefuelpoolintheminimumamountoftime.Furtherdetailsareprovidedinthefollowing.

10.2CouonSurveillance 10.2.1DescritionofTestCouonsTheneutronabsorberusedinthesurveillance programshallberepresentative ofthematerialusedwithinthestoragesystem.Itshallbeofthesamecomposition, producedbythesamemethod,andcertified tothesamecriteriaastheproduction lotneutronabsorber.

Thesamplecouponshallbethesamethickness astheneutronabsorberusedwithinthestoragesystemandshallmeetthereferenced Holtecdrawingdimensional requirements.

Eachneutronabsorberspecimenshallbeencasedinastainless steeljacketofanalloyidentical tothatusedinthestoragesystem,formedsoastoencasetheneutronabsorbing materialandfixitinapositionandwithtolerances similartothatforthestorageracks.Thejacketwouldbesimilartothatforthestorageracks.10-2 Il'lI~~I1 Thejacketwouldbeclosedbyquickdisconnect clampsorscrewswithlocknutsinsuchamannerastoretainitsformthroughout theuseperiodandalsoallowrapidandeasyopeningwithout.contributing mechanical damagetotheneutronabsorberspecimencontained therein.Consistent.

withtheUSNRCOTPositionPaper[reference 10.1.1],requirements ofastatistically acceptable samplesize,atotaloftwelvejacketedneutronabsorberspecimens, shallbeused.10.2.2Benchmark DatThefollowing benchmark testsshallbeperformed ontestcouponsderivedfromthesameproduction runastheactualneutronabsorberpanels.(i)(ii)(iii)Length,width,thickness andweight.measurements Wetchemistry Neutronattenuation measurement (optional) 10.2.3CouonReference DataPriortoencasingthecoupons,eachcouponshallbecarefully calibrated.

Theirwidth,thickness, lengthandweightshallbecarefully measuredandrecorded.

Thewetchemistry willbeperformed onastriptakenfromthesameBoralplatesfromwhichthecouponsaremadetoprovideabenchmark B-10loadingdata.Threepointsoneachcouponwillbedesignated forneutronattenuation measurement.

Neutronattenuation measurements atthosethreepointswillbemadeandrecorded.

10-3 IIiIIII 10.2.4Accelerated Surveillance Atthetimeofthefirstoff-loadofspentfuel,thecoupontreeissurrounded bystoragecellscontaining fuelassemblies fromthepeakpowerregionofthereactorcore.Atthetimeofthesecondoff-loadofthefuelassemblies, thetreeiswithdrawn fromthefuelpoolandonecouponistakenforevaluation.

Thespecimenstripisreplacedinthefuelpoolinanewlocation, whereitisagainsurrounded bypeakpowerregionfuelassemblies.

Thestoragecellthatwasvacatedmaynowbeusedtostoreafuelassembly.

Thisarrangement isrepeatedatthefirsttwooff-loads offuelandafterthat,everythirdoutage.Byevaluation ofthespecimens, anaccelerated monitorofenvironmental effectsontheneutronabsorberwillbeobtained.

10.2.5Post-Erradiation TestsCouponsremovedfrom,thepoolwillbet'estedfordimensional, neutronattenuation, andwetchemistry changesusingthesameprocedures whichwereusedininitialbenchmarking tominimizethepotential forinstrument errors.10.2.6AccetanceCriteriaAplantprocedure willbedeveloped toexecutethecommitments madeinthislicensing submittal.

Equipment requirements, step-by-stepinstructions forexecuting inspections andacceptance criteriawillbedescribed inthatprocedure forusebyplantpersonnel.

10-4 II5l References forSecton10OTPositionforReviewandAcceptance ofSpentFuelStorageandHandlingApplications",

byBrianK.Grimes,USNRC,April14,1978,andRevisiondatedJanuary18,1979.10-5 IIIOI 11.011~1ENVIRONMENTAL COSTBENEFITASSESSMENT Intr'oduction ThespecificneedtoincreasetheexistingstoragecapacityofthespentfuelpoolattheDonaldC.CookNuclearPlantisbasedonthecontinually-increasing inventory inthepool,theprudentrequirement tomaintainfull-core offloadcapability, andalackofviableeconomicalternatives.

Theinventory increasecanbeinferredfromthefuelassemblydischarge schedulecontained inTable-11.1.Theproposedprojectcontemplates thereracking ofspentfuelpoolwithfree-standing, highdensity,poisonedspentfuelracks.Theengineering designandlicensing willbecompleted forafullreracking ofthepool,whichiscurrently onlypartially racked.Engineering anddesignwillalsobecompleted toaccommodate consolidated fuel.Thelicensing effortforconsolidated fuelwill,however,bepursuedatalaterdateifconsolidation ischosentoaccommodate futurestorageneeds.11'ProectCostAssessmetThetotalcapitalcostforthererackproject.isestimated tobeapproximately

$14.1million.Manyalternatives wereconsidered priortoproceeding withreracking, whichisnottheonlytechnical optionavailable toincreaseon-sitestoragecapacity.

Reracking does,however,enjoyacostadvantage overothertechnologies, asshown:11-1 II TeofStoaeRerackFuelconsolidation DrycaskstorageStoragevaultNewpoolCapitalCostsKUg20(1)S20-34(')$45-110(')$40-90()$115(')Therearenoacceptable alternatives todevelopoff-sitespentfuelstorag~capacityfortheCookNuclearPlant.First,therearenocommercial independent spentfuelstoragefacilities operating intheU.S.Second,theadoptionoftheNuclearWastePolicyAct(NWPA)createdadefactothrow-away nuclearfuelcycle.Sincethecostofspentfuelreprocessing isnotoffsetbythesalvagevalueoftheresidualuranium,reprocessing represents anaddedcostforthenuclearfuelcyclewhichalreadyincludestheNWPANuclearWasteFundfees.Inanyevent,therearenodomesticreprocessing facilities.

Third,I&Mhasnootheroperating powerplant;therefore, shipmentofspentfuelfromtheCookNuclearPlanttoothersystemnuclearpowerplantsisnotpossible.

Fourth,at$600,000perdayreplacement powercost,shuttingdowntheCookNuclearPlantismanytimesmoreexpensive thansimplyreracking theexistingspentfuelpools.FromEPRINF-3580,May1984FromDOERW-0220,"FinalVersionDryCaskStorageStudy,"February1989Actualestimated costperKgUofstoragespacegainedforthisproject11-2 IIIII ResourceCommitment Theexpansion ofthespentfuelpoolcapacityisexpectedtorequirethefollowing primaryresources:

Stainless steel360tons.BoralNeutronAbsorber30tons,ofwhich30tonsareBoronCarbidePowderand20tonsarealuminum.

Therequirements forstainless steelandaluminumrepresent asmallfractionoftotalworldoutputofthesemetals(lessthan.0001.).Althoughthefractionofworldproduction ofBoronCarbiderequiredforthefabrication issomewhathigherthanthato'fstainless steeloraluminum, itisunlikelythatthecommitment ofBoronCarbidetothisprojectwillaffectotheralternatives.

Experience hasshownthattheproduction ofBoronCarbideishighlyvariableanddependsuponneed,andcaneasilybeexpandedtoaccommodate worldwide needs.11.4Environment Assessment Duetotheadditional heat-load arisingfromincreased spentfuelpoolinventory, theanticipated maximumbulkpooltemperature increases fromapreviously-licensed 140'Ftoapproximately 160'F,asdetailedinthecalculations described inSection5.0ofthisreport.Theresultant totalheat-load (worst,case)is35.5millionBTU/HR,whichislessthan0.54ofthetotalplantheatlosstotheenvironment.

Thenetresultoftheincreased heatlossandwatervaporemission(duetoincreased evaporation) totheenvironment isnegligible.

11-3 IIIIIII Table11.1DONALDC.COOKNUCLEARPLANTHORSTCASESPENTFUELINVENTORY ASSEMBLIES ItLssTORAB

',19911992199319941995199619971998199920002001200220032004200520062007200820092010201120122013201420152016201713621518167818381918LoseMlcoredischarge capability withcurrentcapacity19982158Losenormaldischarge capability withcurrentcapacity23182318247826382798279829583118319832783438Losefullcoredischarge capability withproposedrerack35983678Losenormaldischarge capability withproposedrerack375839184078415843514431462411-4 IIIIIIII

ML17329A067

Text

1.0 OESCRIPTIQN

2.0 DESCRIPTION

1.0INTRODUCTION

3.0 CONSTRUCTION

1.0INTRODUCTION

3.0 CONSTRUCTION

4.0 CRITICALITY

1.0INTRODUCTION

6.0 STATICANDDYNAMICANALYSIS0RACKSTRUCTURE

7.0 CCIDENTANALYSISANDMISCELLANEOUS

9.0 RADIOLOGICAL

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