ML17319A636

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Safety Analysis for Operation of DC Cook Unit 2 W/Positive Moderator Coefficient.
ML17319A636
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Site: Cook American Electric Power icon.png
Issue date: 09/22/1980
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WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
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NUDOCS 8010010543
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Attachment2toAEP:NRC:00453TransientReanalysisReport

'SAFETYANALYSIS'OROPERATIONOFD.C.COOKUNIT2WITEA'OS'ITIVEMODERATORCOEFFICIENTINTRODUCTIONThissafetyanalysishasbeenperformedtosupporttheproposedTechnicalSpecificationchangeforD.C.CookUnit2whichwouldallowasmall,positivemoderatortemperaturecoefficienttoexist.atpowerlevelsbelow70percentpower.Theresultsoftheanaly-sis,wnicharepresentedbelow,showthattheproposedchangecanbeaccommodatedwithamplemargintotheapplicableFSARsafetylimits.ThepresentD.C.CookUnit2TechnicalSpecificationsrequirethemoderatortemperaturecoefficient(MTC)tobezeroornegativeatalltimeswhilethereactoriscritical.Thisrequirementisoverlyrestrictive,sinceasmallpositivecoefficientatreducedpowerlevelscouldresultinasignificantincreaseinfuelcycleflexibility,butwouldhaveonlyaminoreffectonthesafetyanaly-sisoftheaccidenteventspresentedintheFSAR.TheproposedTechnicalSpecificationschange,giveninAttachment1totheletter,allowsa+5pcm/'F*MTCbelow70percentofratedpower,changingtoa0pcm/'FMTCat70percentpowerandabove.ThisMTCisdiagrammedinFigurel.Apower-leveldependentMTC*1pcm=10hk/k waschosentominimizetheeffectofthespecificationchangeonpostulatedaccidentsathighpowerlevels.Moreover,asthepowerlevelisraised,theaveragecoolanttemperaturebecomeshigherasallowedbytheprogrammedaveragetemperaturecontrollerfortheplant,tendingtobringthemoderatorcoefficientmorenegative.Also,theboronconcentrationcanbereducedasxenonbuildsintothecore.Thus,thereislessneedtoallowapositivecoefficientIasfullpowerisapproached.Asfuelburnupisachieved,boronisfurtherreducedandthemoderatorcoefficientwilleventuallybecomenegativeovertheentireoperatingpowerrange.ACCIDENTANALYSISTheimpactofapositivemoderatortemperaturecoefficientontheaccidentanalysespresentedinChapter14oftheD.C.CookUnit2FSAR(1)hasbeenassessed.Thoseincidentswhichwerefoundtobesensitivetopositiveornear-zeromoderatorcoefficientswerereanalyzed.Ingeneral,theseincidentsarelimitedtotransientswhichcausethereactorcoolanttemperaturetoincrease.Withoneexception,theanalysespresentedhereinwerebasedona+5pcm/'Fmoderatortemperaturecoefficient,whichwasassumedtoremain-constantforvariationsintemperature. Theanalysisinwhichthiswasnotthecase,wasthecontrolrodejectionanalysiswhichwasbasedonacoefficientequalto+5pcm/Fatzeropowernominalaveragetemperatureandwhichbecamelesspositiveforhighertemperatures.ThiswasnecessarysincetheTWINKLEcomputercode,onwhichtheanalysisisbased,isadiffusion-theorycoderatherthanapoint-kineticsapproximationandthemoderatortemperaturefeedbackcannotbeartificiallyheldconstantwithtemperature.Forallaccidentswhichwerereanalyzed,theassumptionofapositivemoderatortemperaturecoefficientexistingatfullpowerisconservativesincetheproposedTechnicalSpecificationrequiresthatthecoefficientbezeroornegativeatorabove70percentpower.Zngeneral,thereanalysiswasbasedontheidenticalanalysismethods,computercodes,andassumptionsemployedintheFSAR;anyexceptionsarenotedinthediscussionofeach,incident.Accidentsnotre-analyzedincludedthoseresultinginexcessiveheatremovalfromthereactorcoolantsystemforwhichalargenegativemoderatorcoefficientismorelimiting,andthoseforwhichheatupeffectsfollowingreactortriparenotsensitivetothemoderatorcoefficient.TableIgivesalistofaccidentspresentedintheD.C.CookUnit2FSARanddenotesthoseeventsreanalyzedforapositivecoefficient.Z.TransientsNotAffectedBaPositiveModeratorCoefficientThefollowingtransientswerenotreanalyzedsincetheyeitherresultinareductioninreactorcoolantsystemtemperatureandaretherefore

~'~sensitivetoanegativemoderatortemperaturecoefficient,orareotherwisenegligiblyaffectedbyapositivemoderatortemperaturecoefficient.A.RCCAMisa'linment/DroTheRCCAdropcasepresentedinSection14.1.3oftheFSARispotentiallyaffectedbyapositivemoderatortemperaturecoefficient.Useofapositivecoefficientintheanalysiswouldresultinalargerreductionincorepowerlevelfollow-ingtheRCCAdrop,therebyincreasingtheprobabilityofareactortrip.Forthereturntopowerwithautomaticrodcontrolcase,apositivecoefficient(whichwouldonlyexistbelow70percentpower)wouldresultinasmallincreaseinthepowerovershoot.Westinghousehasperformedextensiveanalysesinthisarea.whichhasdemonstratedthatthelimitingconditionsforthistransientareatornear100percentpowerwherethemoderatortemperaturecoefficientmustbezeroornegative.Onthisbasis,theanalysisforthiseventwasnotrepeated.B.StartuofanInactiveReactorCoolantLooAninadvertentstartupofanidlereactorcoolantpumpresultsinadecreaseincoreaveragetemperature.Asthemostnega-tivevaluesofmoderatorreactivitycoefficientproducethegreatestreactivityaddition,theanalysisreportedintheFSAR,Section14.1.7,represents'helimitingcase.

Ig'~'-5-C.'xc'e's'sive'e'atR'emova'1Du'et'o'.Fee'dwater'S'stemMa'1'funct'ionsTheadditionofexcessivefeedwaterorthereductionoffeed-watertemperatureareexcessiveheatremovalincidents,andareconsequentlymostsensitivetoanegativemoderatortemperaturecoefficient.ResultspresentedinSection14.1.10oftheFSARJlbasedonanegativecoefficient,representthelimitingcase.D.'xcessiveLo'adincreaseAnexcessiveloadincreaseevent,inwhichthesteamloadexceedsthecorepower,resultsinadecreaseinreactorcool-antsystemtemperature.Withthereactorinmanualcontrol,theanalysispresentedinSection14.1.11oftheFSARshowsthat,thelimitingcaseiswithalargenegativemoderatorcoefficient.Xfthereactorisinautomaticcontrol,thecontrolrodsarewithdrawntoincreasepowerandrestoretheaveragetemperaturetotheprogrammedvalue.TheanalysisofthiscaseintheFSARshow@thattheminimumDNBRisnotsensitivetomoderatortemperaturecoefficient.Therefore,theresultspresentedintheFSARarestillapplicabletothisincident.E.Los's'fNormalFeedwater,LossofOffsitePowerThelossofnormalfeedwaterandlossofoffsitepoweracci-dents(Sections14.1.9and14.1.12oftheFSAR)areanalyzedtodeterminetheabilityofthesecondarysystemtoremovedecayheat.Theseeventsarenotsensitivetoapositive moderatorcoefficientsincethereactortripoccursatthebeginningofthetransientbeforethereactor,coolantsystemtemperatureincreasessignificantly.Therefore,theseeventswerenotreanalyzed.F.RutureofaMainSteamPieSincetheruptureofamainsteampipeisatemperaturereduc-tiontransient,minimumcoreshutdownmarginisassociatedwithastrongnegativemoderator=temperaturecoefficient.TheworstconditionsforasteamlinebreakarethereforethoseanalyzedintheFSAR(Section14.2.5).G.L'ossofCoolantAccident(LOCA)Thelossofcoolantaccident(Section14.3oftheFSAR)isanalyzedtodeterminethecoreheatupconsequencescausedbyaruptureofthereactorcoolantsystemboundary.TheeventresultsinadepressurizationoftheRCSandareactorshutdownatthebeginningofthetransient.ThisaccidentwasnotreanalyzedsincetheTechnicalSpecificationrequirementthatthetemperaturecoefficientbezeroornegativeat70percentpoweroraboveensuresthatthepreviousanalysisbasisforthiseventisnotaffected.XZ.TransientsSensitivetoaPo'sitive'od'erator'o'e'ffi'c'i'entA.pron'ilut'i"onAsstatedinSection14.1.5oftheFSAR,anuncontrolledborondilutionincidentcannotoccurduringrefuelingdue'toadmin-istrativecontrolswhichisolatethereactorcoolantsystem

~~I-7-fromthepotentialsourceofunboratedwater.Ifaborondilutionincidentoccursduringstartup,theFSARshowsthattheoperatorhassufficienttimetoidentifytheprobl'emandterminatethedilutionbeforethereactorreturnstocriti-cality.Therefore,thevalueofthemoderatorcoefficienthasnoeffectonaborondilutionincidentduringstartup.Thereactivityadditionduetoaborondilutionatpower'illcauseanincreaseinpowerandreactorcoolantsystemtemperature.Duetothetemperatureincrease,apositivemoderatorcoefficientwouldaddadditionalreactivityandincreasetheseverityofthetransient.Withthereactorinautomaticcontrol,however,therodinsertionalarmsprovidetheoperatorwithadequatetimetoterminatethedilutionbeforeshutdownmarginislost.Aborondilutionincidentwiththereactorinmanualcontrolisnomoreseverethanarodwithdrawalatpower,whichisanalyzedbelowandtherefore'thiscasewasnotspecificallyanalyzed.Followingreactortrip,theamountoftimeavailablebeforeshutdownmarginislostisnotaffectedbythemoderatorcoefficient.,B.'ontrolRodWithdrawalFromaSubcriticalCon'di:t'i.'onIntro'ductionAcontrolrodassemblywithdrawalincidentwhenthereactorissubcriticalresultsinanuncontrolledadditionofreactivityleadingtoapowerexcursion(Section14.1.1oftheFSAR).The nuclearpowerresponseischaracterizedbyaveryfastriseterminatedbythereactivityfeedbackofthenegativefueltemperature(ie.Doppler)coefficient.Thepowerexcursioncausesaheatupofthemoderatorandfuel.Thereactivityaddition'uetoapositivemoderatorcoefficientresultsinincreasesinpeakheatfluxandpeakfuelandcladtemperatures.MethodofAnalsisTheanalysiswasperformedintheFSARforareactivityinser-tionrateof75pcm/sec.However,thisvaluewasfoundtobeoverlyconservativebasedontheactualcyclevaluesforD.C.CookUnit2(2).Areactivityinsertionrateof60pcm/secwhichisstillaveryconservativevaluewasusedintheanalysiswithapo'sitivemoderatorcoefficient.Thisassumedreactivityinsertionrateisgreaterthanthatforthesimultaneouswithdrawalofthecombinationofthetwosequen-tialcontrolbankshavingthegreatest.combinedworthatmaximumspeed(45inches/minute).Aconstant.moderatortemperaturecoefficientof+5pcm/'Fwasusedintheanalysis.Thedigitalcomputercodes,initialpowerlevel,andreactortripinstrumentdelaysandsetpointerrorsusedintheanalysiswerethesameasusedintheFSAR.ResultsandConclusionsThenuclearpower,coolanttemperature,heatflux,fuelaveragetemperature,andcladtemperatureversustimefora60pcm/sec

~I~I-9-insertionrateareshowninFigures2through4.Thisinsertionrate,coupledwithapositivemoderatortemperaturecoefficientof+5pcm/F,yieldsapeakheatfluxwhichdoesnotexceedthatpresentedintheFSAR.ThereforetheconclusionspresentedintheFSARarestillapplicable.C.UncontrolledControlRodAssemblWithdrawa'1'at.'o'werIntroductionAnuncontrolledcontrolrodassemblywithdrawalatpowerproducesamismatchinsteamflowandcorepower,resultinginanincreaseinreactorcoolanttemperature.ApositivemoderatorcoefficientwouldaugmentthepowermismatchandcouldreducethemargintoDNB.AdiscussionofthisincidentispresentedinSection14.1;2oftheFSAR.MethodofAnalsisThetransientwasreanalyzedemployingthesamedigitalcomputercodeandassumptionsregardinginstrumentationandsetpointerrorsusedfortheFSAR.Thistransientwasonlyanalyzedat100percentpowerwithapositivemoderatorcoefficientsincethiscaseisthemostlimitingofthosepresentedintheFSAR.Aconstantmoderatorcoefficientof+5pcm/'Fwasusedintheanalysis.Theassumptionthatapositivemoderatorcoefficientexistsatfullpowerisconservativesinceatfullpowerthemoderatorcoefficientwillactuallybe'egative.Forthi'scase,theDNBevaluationwasperformedusingtheimprovedthermaldesignprocedure(3). ResultsFigure5showstheminimumDNBRasa.functionofreactivityinsertionrate.ThelimitingcaseforDNBmarginisare-activityinsertionrateof0.6pcm/secfromfullpowerinitialconditionswhichresultsinaminimumDNBRof1.98.ApositivemoderatorcoefficientthereforedoesnotlowertheDNBRassociatedwithacontrolrodassemblywithdrawalatpowerbelowthelimitvalueof1.80.ConclusionsTheseresultsdemonstratethattheconclusionspresentedintheFSARarestillvalid.Thatis,thecoreandreactorcoolantsystemarenotadverselyaffectedsincenuclearfluxandover-temperaturehTtripspreventthecoreminimumDNBratiofromfallingbelow1.80forthisincident.LossofReactorCoolantFlowIntroductionAsdemonstratedintheFSAR,Section14.1.6,themostseverelossofflowtransientiscausedbythesimultaneouslosso'electricalpowertoallfourreactorcoolantpumps.Thistran-sientwasreanalyzedtodeterminetheeffectofapositivemoderatortemperaturecoefficientonthenuclearpowertran-sientandtheresultanteffectontheminimumDNBRreachedduringtheincident.Theeffectonthenuclearpowertransientwouldbelimitedtotheinitialstagesoftheincidentduring 1~iiIIQ~-11-whichreactorcoolanttemperatureincreasessincethisincreaseisterminatedshortlyafterreactortrip.Method'fAnalsisAnalysismethodsandassumptionsusedinthere-evaluationwereconsistentwiththoseemployedintheFSAR.Thedigitalcomputercodesusedtocalculatetheflowcoast-downandresultingsystemtransientwerethesameasthoseusedtoperformtheFSARanalysis.Theanalysiswasdonewithaconstantmoderatorcoefficientof+5pcm/~FandtheDNBevaluationwasperformedusingtheimprovedthermaldesignprocedure(3).ResultsFortheanalysisperformedwitha+5pcm/Fmoderatorcoefficient,thereactorcoolantaveragetemperatureincreaseslessthan2'Fabovetheinitialvalue.Therefore,apositivemoderatorcoefficientdoesnotappreciablyaffect.thereactorcoolantsystemresponseortheminimumDNBRreachedduringthetransient.Forthiscase,aminimumDNBRof2.08wasobtained.Figures6through8showtheflowcoastdown,thenuclearpowerandheatfluxtransients,andtheminimumDNBRversustime. ConclusionsApositivemoderatortemperature'coefficientdoesnotappreciablyaffecttheresultofthecompletelossofflowtransient,andtheminimumDNBRremainsabovethelimitvalueof1.80forthisincident.ThiscasewasanalyzedsinceitisthemostlimitingonepresentedintheFSAR.Sincethetransientcausesonlyasmallchangeincoreaveragemoderatortemperature,andthepositivemoderatorcoefficientdoesnotappreciablyaffect.thenuclearpowertransient,thesinglepumplossofflowcaseswillalsonotbeappreciablyaffected.LockedRotorXntroductionTheFSAR(Section14.1.6),showsthatthemostseverelockedrotorincidentisaninstantaneousseizureofareactorcoolantpumprotorat100percentpowerwithfourloopsoperating.Followingtheincident,reactorcoolantsystemtemperaturerisesuntilshortlyafterreactortrip.Apositivemoderatorcoefficient.willnotaffectthetimetoDNBsinceDNBisconservativelyassumedtooccuratthebeginningoftheincident.Thetransientwasreanlayzed,however,duetothepotentialeffectonthenuclearpowertransientandthusonthepeakreactorcoolantsystempressureandfueltemperatures.Meth'odofAnalsisThedigitalcomputercodesusedinthereanalysistoevaluate thepressuretransientandthermaltransientwerethesameasthoseusedintheFSAR.Theassumptionsusedwerealsocon-sistentwiththoseemployedintheFSAR.Ananalysiswasdoneat70percentpowerwithamoderatorcoefficientof'+5pcm/'Finordertoshowthatthiscaseisnotmorelimitingthanthe100percentpower,0pcm/FcasepresentedintheFSAR.Thiscaseissufficienttoillustratetheimpactonthetransientbyapositivemoderator.coefficient,sincethemoderatorcoefficientwillactuallybezeroornegative-atfullpower.ResultsandConclusionsTableIIcomparesresultsobtainedforthiscasewiththosepresentedinthe-FSAR.Asshowninthetable,theFSARanaly-sisatfullpowerwithazeromoderatorcoefficientismorelimitingthanthe70percentpowercasewithapositivemoderatorcoefficient.Therefore,theconclusionspresentedintheFSARarestillapplicable.L'ossofExternalElectricalLoadIntroductionTwocases,analyzedforbothbeginningandendoflifeconditions,arepresentedinSection14.1.8oftheFSAR-l.Reactorinautomaticrodcontrolwithoperationofthepressurizersprayandthepressurizerpoweroperatedreliefvalves;and 2.Reactorinmanualrodcontrolwithnocreditforpressurizersprayorpower'operatedreliefvalves.Asthemoderatortemperaturecoefficientwillbenegativeatendoflife,onlybeginningoflifecaseswererepeated.Theresultofalossofloadisacorepowerlevelwhichmomentarilyexceedsthesecondarysystempowerremovalcausinganincreaseincorewatertemperature.Theconsequencesofthereactivityadditionduetoapositivemoderatorcoefficient.areincreasesinbothpeaknuclearpowerandpressurizerpressure'.MethodofAnalsisAconstantmoderatortemperaturecoefficientof+5pcm/~Fwasassumed.ThemethodofanalysisandassumptionsusedwereotherwiseinaccordancewiththosepresentedintheFSAR.Theimprovedthermalprocedure(3)wasutilizedintheDNBevaluation.ResultsThesystemtransientresponsetoatotallossofloadfrom102percentpower,withcontrolrodsinautomaticcontrol,assumingpressurizerreliefandsprayvalves,isshowninFigures9and10.PeakRCSpressurereaches2567psiafollowingareactortriponovertemperaturehT.Thiscomparestoavalueof2493psiapresentedintheFSAR.AminimumDNBRof2.30isreachedshortlyafterreactortrip. PFigureslland12illustratereactorcoolantsystemresponsetoalossofloadwithrodsinmanualcontrol,assumingnocreditforpressurecontrol.PeakRCSpressurereaches'604psiafollowingreactortriponhighpressurizerpressure.ThepeakpressurereachedintheFSARanalysisforthiscasewas2597psia.TheminimumDNBRisinitially2.71andincreasesthroughoutthetransient.ConclusionsTheanalysisdemonstratesthattheintegrityofthecoreandthereactorcoolantsystempressureboundaryduringalossofloadtransientwillnotbeaffectedbyapositivemoderatorreactivitycoefficientsincetheminimumDNBratioremainswellabovethe1.80limit,andthepeakreactorcoolantpressureislessthan110percentofdesign.Therefore,theconclusionspresentedintheFSARarestillapplicable.RuptureofaControlRod.DriveMechanismHousin/ControlRodE'ectionintroductionTherodejectiontransientisanalyzedatfullpowerandhotstandbyforbothbeginningandendoflifeconditions.Sincethemoderatortemperaturecoefficientisnegativeatendoflife,onlythebeginningoflifecaseswerereanalyzed.Thehighnuclearpowerlevelsandhotspotfueltemperaturesresultingfromarodejectionareincreasedbyapositive moderatorcoefficient.AdiscussionofthistransientispresentedinSection14.2.6oftheFSAR.Metho'dofAnalsisThedigitalcomputercodesforanalysesofthenuclearpower'ransientandhotspotheattransferarethesameasthoseusedintheFSAR.TheejectedrodworthsandtransientpeakingfactorswerethesameasreportedinReference3.Themoderatorcoefficientusedforthistransientwas+5pcm/'Fatzeropowernominalaveragetemperature,decreasingtoapproximately+4pcm/'FatfullpowerT-a'verage.Th'isisstillaconservativeassumptionsincethemoderatorcoefficientactuallyiszeroornegativeabove70percent.power.ResultsandConclusionsPeakfuelandcladtemperaturesandnuclearpowerversustimeforbothfullpowerandhotstandbyarepresentedinFigures13through16.AcomparisonofreanalysisandFSARresultsispresentedinTableIII.Thelimitingpeakhotspotcladtemperature,2469F,wasreachedinthehotfullpowercase.Maximumfueltemperatureswerealsoassociatedwiththefullpowercase.Althoughthepeakhotspotfuelcenterlinetemperatureforthistransientexceeded-themeltingpoint,meltingwasrestrictedtolessthantheinnermost10percent.ofthepellet.Asfuelandcladtemperaturedonotexceedthefuelandclad limitsspecifiedintheFSAR,thereisnodangerofsuddenfueldispersalintothecoolant,orconsequentialdamagetotheprimarycoolantloop.Therefore,theeffectsofapositiveMTCofthemagnitudedescribedaboveisacceptable.SUMMARYInordertoassesstheeffectonaccidentanalysisofoperationofD.C.CookUnit2withaslightlypositivemoderatortemperaturecoefficient,asafetyanalysisoftransientssensitivetoapositivemoderatorcoefficientwasperformed.Thesetransientsincludedcontrolrodassemblywithdrawalfromsubcritical,controlrodassemblywithdrawalatpower,lossofreactorcoolantflow,lossofexternalload,andcontrolrodejection.Thisstudyindicatedthatasmallpositivemoderatorcoefficientdoesnotresultintheviolationofanyapplicablesafetylimitsforthetransientsanalyzed.Exceptasnoted,theanalysesemployedaconstantmoderatorcoefficientof+5pcm/F,independentofpowerlevel.Theresultsofthisstudyareconservativefortheaccidentsinvestigatedatfullpower,sincetheproposedTechnicalSpecificationrequiresthatthecoefficientbezeroornegativeatorabove70percentpower.

REFERENCESl.DonaldC.CookNuclearPlant,Unit2,FinalSafetyAnalysisReport,Amendment75,datedApril1977andsupplements,DocketNo.50-316.2.ReloadSafetyEvaluationReport,D.C.CookNuclearPlant,Unit2,Cycle2,July1979,(letterNo.AWF-311,8/17/79).3.Chelemer,H.,Boman,L.H.andSharp,D.R.,"ImprovedThermalDesignProcedure,"WCAP-8567,July1975(Proprietary)andWCAP-8568(Non-Proprietary).

TABLEIACCIDENTSEVALUATEDFORPOS'ITIVE'ODERATORCOEFFICIENTEFFECTS'SARAccidentTimei:n'i:fe*14.1.1*14.1.214.1.3/4*14.1.5*14.1.614.1.7*14.1.81'4.1.914.1.1014.1.1114.1.12RCCAWithdrawalfromSubcriticalRCCAWithdrawalfromPowerRCCAMisalignment/DropBoronDilutionLossofPlow/LockedRotorStartupofanInactiveLoopLossofLoad/TurbineTripLossofFeedwaterFeedwater,MalfunctionExcessiveLoadIncreaseStationBlackoutBOCBOCBOCBOCBOCEOCBOCEOCBOC/EOC14.2.5*14.2.614.2.8SteamLineBreakRCCAEjectionFeedLineBreak(Supplement)EOCBOC14.3LOCABOC*AccidentsEvaluatedBOC-BeginningofCycleEOC-EndofCycle TABLEIICOMPARISONQF'ESULTS'QR'OCKED'OTOR'ANALYSESThisStu'dFSARModeratortemperaturecoefficient,hk/k/'F5x10-5Initialpowerlevel,percentofnominal70100Peakfuelpelletav.temperature,'F22532906Peakcladtemperatureduringtransient,'F15861878Peakreactorcoolantsystempressure,psia25212633 TABLEIII"SU1SGWYOF'ODEJECTIONRESULTS'EGINNING'OFCYCLE(ThisStudy)HotZeroPowerHotFullPowerMaximumfuelpelletaveragetemperature,'F29354088Maximumfuelcentertemperature,'F34404985Maximumcladaveragetemperature,'F22212469Maximumfuelenthalpy,cal/gm121179Fuelpelletmelting,percent.<10

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)t~~a~~'~-0h9.9;Z.gI1.52TINE(SECONDS)FIGURE8LOSSOFFLOWDNBRVSTIME oI~I1%~~1~04lOCD0.6mu04.tL2'~~~~.25002400'n,2300Cll2200men210020001900a-1800.50.4.5.403.53.052.52.01.51.3~0~'0Zo30TIME(SECONOS)50FIGURE9LOSSOFLOAOAUTOMATICROOCONTROLWITHPRESSURIZERRELIEFANOSPRAYC~

\I1~~~;NN~~1$g0~~~12501NO~150NOKO~e675ca650625~Pu6005755500102030TIME(SECONDS)4050FIGURE10LOSSOFLOADAUTOMATICRODCONTROLWITHPRESSURIZERRELIEFANDSPRAY LQClCQCD~CD~CD5~CDCC1.0080.60.402MO~~~1Vtttt~~tICC4/l~CllLalCCLIJ~t4CLCCCACf)telCgCL'26002500240023002200210020001900saooT.~C06.0555.04.5a.o3;53.02.52.0"0,'0II20',30tTIME{SECONOS)50'IGURE11LOSSOFLOAOMANUALROOCONTROLNOPRESSURIZERRELIEFORSPRAY 560~~540~RO~~-'20MTT501500u-1250~~1000750V7C)50025005905805705601020.30TIME(SECONOS)50FIGURf12LOSSOfLOAOMANUALRODCONTROLNOPRESSURIZERRELIEFORSPRAY

~f6.50.-002.TINE(SECONOS)'FIGURE13ROOEJECTIONBOLHFPNUCLEARPOlrlERVSTINE 5000$000400030002000FUELCENTERTEMPERATUREFUELAYERAGETEMPERATURECLADOUTERTEMPERATURE4900'FMELTING100003TIME(SECONDS)FIGURE14RODEJECTIONBOLHFPTEMPERATUREVSTIME 101.01.52.02.53.0TIME(SECONOS)FIGURE15ROOEJECTIONSOLHZPNUCLEARPOMERVSTIME

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