ML17334B421

DC Cook Nuclear Plant Units 1 & 2 Individual Plant Exam Summary Rept.

ML17334B421
Person / Time
Site:	Cook
Issue date:	04/30/1992
From:	INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
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ML17329A488	List: ML17329A487 ML17329A492 ML17334B421
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INDIVIDUALPLANTEXAMINATIONSUMMARYREPORTTABLEOFCORIENTST~P~I1.02.0EXECUTIVESUMMARY1.1BackgroundandObjectives1.2PlantFamiliarization1.3OverallMethodology1.4SummaryofMajorFindingsEXAMINATIONDESCRIFI'ION2,1Introduction2.2ConformancewithGenericLetterandSupportingMaterial2.3GeneralMethodology2,4InformationAssembly2,5TreatmentofDualUnitsPAAK.'~-'1~1"'1-11-2~1-2""1-3~'2-1-2-12-22-3242-113.0FRONT-ENDANALYSIS3-13.1AccidentSequenceDelineation3-13.1.13.1.23.1.33.L43.1.53.2SystemAnalysisInitiationEventsFront-LineEventTreesSpecialEventTreesSupportSystemEventTreeSequenceGroupingandBack-EndInterface-3-13-5344-3M344346.3,2.1SystemDescriptions3.2.2SystemAnalysis3.2.3SystemDependencies3,3SequenceQuantification3-663-1243-1263-1293.3.13.3.23.3.3ListofGenericDataPlantSpecificDataandAnalysisHumanFailureData3-1293-1293-145 TABLEOFCORII<2fIS(Cont'd.)HHMIc'"-C(('.y"l~4[0-r.r6o-'g<Ig5<('J5.0(I}C:-.'L-v'-gri.ic":M(}C<*E.6.0Yil"St-.c.~Wl~~CommonCauseFailureDataQuantificationofUnavailabilityofSystemsandFunctionsQuantificationofSequenceFrequenciesInternalFloodingAnalysisCi(<('(3.4ResultsandScreeningProcess(.'3,4.1(ApplicationofGenericLetterScreeningCriteria3.4,2~VulnerabilityScreening3.4.3DecayHeatRemovalEvaluation3.4.4USIandGSIScreeningBACK-ENDANALYSIS~'4.1.ContainmentAnalysis.4.2HantModels,and(methodsforPhysicalProcesses4.3ContainmentFailureCharacterization4.4ContainmentEventTree4.5CETQuantification4.6BinsandPlantDamageStates4.7AccidentProgressionandRadionudideReleaseCategoriesUTILITYPARTICIPATIONANDINTERNALREVIEWTEAM5.1IPEProgramOrganization5.2CompositionofIndependentReviewTeam5.3AreasofReview,MajorComments,andResolutionofComments5.4LivingPRAProgramPLANTIMPROVEMENTSANDUNIQUESAFETYFEATUIUQSUMMARYANDCONCLUSIONSLISTOFREFERENCESAPPENDIXA("..'.au>>+%OFFSlTECONSEQUENCES'ANALYSIS~PAE3-1593-1623-1643-1643-1663-1663-1873-1873-1924-14-74-164-174-234-234-385-15-154546-17-18-1A-1~lkll LISTOFTABLESTABLE~PAG2.4-1CookNuclearPlantIPEInformationSources3.1-13.1-23.1-33.1Q3.1-53.1-63.1-73.1-83.1-93.1-103.1-113.1-123.1-133.1-143.1-153.1-163.1-17SummaryofInternalInitiatingEventFrequencies'argeLOCASystemSuccessCriteriaMediumLOCASystemSuccessCriteriaSmallLOCASystemSuccessCriteriaSteamGeneratorTubeRuptureSystemSuccessCriteriaInterfacingSystemLOCASystemSuccessCriteria'reaksBeyondECCSCapabilitySystemSuccessCriteriaTransientsWithSteamConversionSystemsAvailableSystemSuccessCriteriaTransientsWithoutSteamConversionSystemsAvailableSystemSuccessCriteriaLargeSteamLine/FeedlineRuptureSystemSuccessCriteriaLossofOffsitePowerSystemSuccessCriteriaStationBlackoutSystemSuccessCriteriaAnticipatedTransientWithoutScramSystemSuccessCriteriaLossofEssentialServiceWaterSystemSuccessCriteriaLossofComponentCoolingWaterSystemSuccessCriteriaLossofSingleTrainof250VDCElectricPowerSystemS~essCriteriaInternalFloodingSystemSuccessCriteria343-233-253-283-303-343-363-373M3423453473-513-543-573403423.2-1302-2312-33.243.3-13,3-230333.343.3-53.3-63.3-73.4-13.4-23.4-33.44OutlineforSystemNotebooksSystemsModeledintheCookNuclearPlantIPEFrontlineSystemDependencyonSupportSystemsSupportSystemDependencyonSupportSystemshDataProcessingTableHEPDataDescriptiveHRAScalingGuidesDependenceLevelDefinitionsI<SummaryofHumanErrorProbabilities%1j'ookNuclearPlantIPEMGLCommonCauseFactorsUnavailabilityofSystemsandFunctionsAccidentEventSummarySummaryofSignificantSequences.CDF.OUTCDF.IMP~s~slk,~iSC*43473483-1273-1283-1303-1483-1523-1543-1553-1613-163V':3-1673~1683-1823~1854,2-1PhenomenologicalEvaluationSummaries,onPostulatedContainmentFailureModes4.6-14.6-24.6-34.64DominantSequenceListEndStatesSelectedforAnalysesBinningofBoundedSequencesReleaseCategoryDefinition4-284-324-334-344.7-14.7-24,7-34.74ContainmentStatusandLevelIISourceTermSummaryofDominantSequencesEnvironmentalReleaseReleaseCategoryandProbabilityAnalysestoAddressUncertaintiesDiscussedinNUREG-13354694-754-764-77Iu LISPOFTABLES(Cont'd.)>>e-TABLE4:7-547-6I'-5.2-1"A'-'1":I-'>>91j:Frr+<<'ARangeofMAAPModelParametersAccordingtoEPRITR-100167RangeofAirborneFissionProductReleaseunderDifferentContainmentFailureScenariosIndependentReviewTeamRepresentationLevelIIIOffsiteConsequenceResultsPAE4-794-815-5A-2~~'br<.n>>'C,l.8sy""gCpr:.-'nt'~>>>>~.a>>l'oQ".<lb1'1'-'ol~81>>~>>>>'12.

LISFOFFIGURESPAE3.1-13.1-23.1-33.143.1-53.143.1-73.1-83.1-93.1-103.1-113.1-123.1-133.1-143.1-153.1-163.2-1302-23.2-33.243.2-53.2-6312-73.2-83.2-93.2-103.2-113.2-123.2-133.2-143.2-153.2-163.2-173,2-183.2-193.2-203.2-2130222302233.2-243.2-253.2-263.2-273.2-28LargeLOCAEventTreeMediumLOCAEventTreeSmallLOCAEventTreeSteamGeneratorTubeRuptureEventTreeInterfacingSystemsLOCAEventTreeBreaksBeyondECCSCapabilityEventTreeTransientsWithSteamConversionSystemsAvailableEventTreeTransientsWithoutSteamConversionSystemsAvailableEventTreeLargeSteamLine/FeedlineBreakEventTreeLossofOffsitePowerEventTreeStationBlackoutEventTreeAnticipatedTransientWithoutScramEventTreeLossofEssentialServiceWaterEventTreeLossofComponentCoolingWaterEventTreeLossofaSingleTrainof250VDCEventTreeInternalFloodingEventTreeFlowDiagramComponentSymbolsAuxiliaryFeedwaterSystemSimplifiedFlowDiagramContainmentSpraySystemSimplifiedFlowDiagram-StandbyConditionsContainmentSpraySystemSimpliTiedFlowDiagram-InjectionPhaseContainmentSpraySystemSimplifiedFlowDiagram-RecirculationPhaseComponentCoolingWaterSystemSimplifiedFlowDiagramEssentialServiceWaterSystemSimplifiedFlowDiagramNonessentialServiceWaterSystemSimplifiedFlowDiagram-NormalOperatingConditionsNonessentialServiceWaterSystemSimplifiedFlowDiagram-StationBlackoutCompressedAirSystemSimplifiedFlowDiagramAccumulatorSystemSimplifiedFlowDiagramLowHeadCoolingSystemSimpliTiedFlowDiagram-InjectionPhaseLowHeadCoolingSystemSimplifiedFlowDiagram-RecirculationPhaseHighHeadCoolingSystemSimplifiedFlowDiagram-NormalOperatingConditionsHighHeadCoolingSystemSimplifiedFlowDiagram-InjectionPhaseHighHeadCoolingSystemSimplifiedFlowDiagram-RecirculationPhaseElectricPowerSymbolsOffsitePowerSourcesSimplifiedOne-LineDiagramAlternateOffsitePower250VDCElectricPowerSystemSimplifiedOne-LineDiagramTypical120VACVitalBusInstrumentSystemSimplifiedOne-LineDiagramTypical120VACPanel(ELSC,AFW)Feedwater/CondensateSystemSimplifiedFlowDiagramCirculatingWaterSystemSimplifiedFlowDiagramMainSteamSystemSimpliTiedFlowDiagramPressurizerPORVandSafetyValvesSimplifiedFlowDiagramContainmentAirRecirculationandHydrogenSkimmerSystemSimplified'lowDiagramHydrogenIgniters(DistributedIgnitionSystem)SimpliTiedFlowDiagram,3-73-8,3pI'-103-11)3-123-133-143-153-163-173-183-193-203-213-223493-723-743-753-763-793-823443453-883-913-933-943-963-973-983-1023-'1033-1043"-1073-1103-1113-1143-1153-1173-1193-"1213-123

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1.0FZG".CUTIVESUMMARYInNovember1988,theU.S.NuclearRegulatoryCommission(NRC)staffissuedGenericLetter88-20,"IndividualHantExaminationforSevereAccidentVulnerabilities-10CFR50.54(f),"whichestablishedaformalrequestforutilitiestoperformanIndividualPlantExamination(IPE).InadditiontotheperformanceoftheIPE,thisletterrequestedutilitiestoidentifypotentialimprovementstoaddresstheimportantcontributorstoplantriskandimplementimprovementsthattheybelievedwereappropriatefortheirplant.InAugust1989,theNRCissuedSupplement1toGenericLetter88-20,"InitiationoftheIndividualHantExaminationforSevereAccidentVulnerabilities-10CFR50.54(f),"accompaniedbyNUREG-1335,"IndividualPlantExaminationGuidance,"(Reference20)whichprovidedguidancefortheinformationtobereportedbacktotheNRC.InJuly1990,theNRCissuedSupplement3toGenericLetter88-20,"CompletionofContainmentPerformanceImprovementProgramandForwardingofInsightsforUseIntheIndividualHantExaminationforSevereAccidentVulnerabilities,"whichstatedthatlicenseeswithicecondensercontainmentsareexpectedtoevaluatethevulnerabilitytointerruptionofpowertothehydrogenignitersaspartoftheIPE.ThisreportprovidestherequestedinformationfortheDonaldC.CookNuclearPlant,Units1and2.1.1BackgroundandObjectivesInitsSevereAccidentPolicyStatement(50FR43621,Reference32)issuedin1985,theNRCconcludedthatoperatingnuclearplantsposenounduerisktothepublichealthandsafety.However,recognizingthatthesegenericconclusionswerederivedfromadiversebutsmallersampleoftheexistingplants,theNRCrequestedthatalllicenseesperforma"limited-scopeaccidentsafetyanalysis"todetermineiftheremightbeanyuniqueplant-specificvulnerabilitiesleadingtoacoredamageaccidentortopoorcontainmentperformancegivenacoredamageevent.InrespondingtoGenericLetter88-20anditsSupplement1,AmericanElectricPowerServiceCorporation(AEPSC)establishedfivespeciTicobjectivesforthesevereaccidentissueresolutionprogramfortheCookNuclearPlant.Theprogramobjectiveswere:1.Toidentify,evaluate,andresolvethesevereaccidentissuesgermanetotheCookNuclearPlantinarealistic,technicallyacceptablemannerwithemphasisonthepreventionofsuchaccidents.2.Toidentifyanddevelopinputtodecisionmakingprocessesrelativetopotentialenhancementstoplantdesignand/oroperationaimedatreductionofriskfromsevereaccidents.3.Toevolvearealistic,documented,auditableProbabilisticRiskAssessment(PRA)fortheCookNuclearPlantwhichcouldbereadilyusedandmaintainedandwhichwouldbesuitableforongoinguse.4.ToaddresstheexistingNRCinformationrequestinGenericLetter88-20andthoseinformationrequestsanticipatedin'thenearfutureoncloselyrelatedtopics.5.TofamiliarizeAEPSCandCookNuclearPlantstaffswiththebasisandmethodologyofPRAsothat,inthefuture,thePRAcouldbeindependentlymaintainedandupdatedasnecessary.AEPSChascompletedanddocumentedafullscopeLevelIIIPRAfortheCookNuclearPlantthathascompletelymettheseobjectives.Thisreport,containingasummaryofthemethods,results,andconclusions,fullycomplieswiththeNRCrequestforinformationcontainedinGenericLetter88-20,Supplement1.Inaddition,theentirePRAwasconductedaccordingtotheapplicablesectionsof10CFR50,AppendixB,"QualityAssuranceCriteriaforNuclearPowerPlantsandFuelReprocessingPlants."AEPSChasretainedallsupportinganalyses,descriptionsandfilespertainingtothePRA.TheseareavailableatAEPSCofficesforNRCreviewasnecessary.1-1

~'saresultofAEPSC'sdecisiontoperformaLevelIIIPRAincludinganExternalEventsAnalysis,thescope'~'oftheAEPSCPRAprogramgoesbeyondthatdescribedinGenericLetter88-20.ToassistNRCreviewers,thissubmittalisstructuredtocontaintheInternalEventsAnalysis(oftenreferredtoasaLevelIPRA),theContainmentPerformanceAnalysis(referredtoasaLevelIIPRA),andtheConsequenceAnalysis(aLevelIIIPRA).TheExternalEventsAnalysis,includinginternalfire,seismicPRA,andotherexternaleventsanalysisaredescribedinseparatesubmittaldocuments.0)14HantFamiliarizationTheAEPSCPRAprogramfortheCookNuclearPlantinvolvedanextensiveplantfamiliarizationeffort,becausetheundertakingofafull-scoperealisticLevelIIIPRArequiredcarefulanalysisoftheas-built,"'"aswperatedplant.Toaccomplishthisfamiliarization,severaldatacollectionanddocumentationactivitieswereundertakenduringtheinitialphaseoftheproject.Systemnotebookswerepreparedformodelledsystemsafterplantwalkdownsandanalystreviewofdrawings,systemdescriptions,theUpdatedFinalSafetyAnalysisReport(UFSAR,ReferenceI),technicalspecifications(References2and3)andapplicableplantprocedures.Theplantwalkdownswereconductedtoverifythedesignofthesystems,tobecomefamiliarwith'hephysicallayoutoftheplantandtovisualizerestorativeactionsoralternativesystems.Plantrecordswerereviewedtodevelopplantspecificbehavioralcharacteristicssuchascomponentfailureratesandinitiatingeventfrequencies.Also,aspartofthefamiliarizationeffort,theanalystsidentifiedanydifferencesbebveen'hesystemsforUnitsIand2.OnlyUnitIwasspecificallymodelledasthebaseanalysis.12OverallMethodology'heAEPSCIPEwasperformedbyconductingafullscope,realisticLevelIIIPRA.InperformingtheIPE,standardPRAsystemsanalysispracticessuchasthoseoutlinedinthePRAProceduresGuide(NUREG/CR-2300,Reference26)wereused.TheCookNudearPlantIPEisafullscopeinvestigationoftheplantsystemsandoperatorresponse.Thefocusofinvestigationwasontheperformanceoftherealisticassessmentoftheplantresponsetopotentialaccidentsequences.Themodelsofplantsystemsaredetailedandexplicitlyincludetheperformanceofallkeycomponents.Thesuccesscriteriausedtodeterminewhetherornotplantsystemsachievetheirintended",safetyfunctionwererealisticallydeterminedforeachimportantaccidentsequence.Ratherthanrelyingsolely'onReferenceItosetthesuccesscriteriaforsystemandoperatorperformedactions,thesuccesscriteria'efinitioninvolvedconsiderationofbothsystemcapabilityandtiming.This,inturn,involvedtheanalysisofplantresponsetoavarietyofaccidentscenariosusingtheModularAccidentAnalysisProgram(MAAP)code(Reference13)andotherinformationaswell."'WellknownapproachesforcommoncausefailureandhumanerrorwereadoptedfortheCookNuclearPlantIPE.Indeterminingtheparametricvaluestobeusedinthequantification,availableindustrydatabasesiyerescrutinizedtoassureeventsandfailuremodesappropriatefortheCookNudearPlantanditsequipmentw'ereutilized.Forcommoncauseanalyses,theMultipleGreekLetter(MGL)methodwasused.HumanReliabilityAnalysis(HRA)wasperformedusingTechniqueforHumanErrorRatePrediction(THERP)(Reference22)methodology.Realismwasachievedthroughdetailedmodelingofoperatoractionsandthoroughtreatmentofoperatorrecovery.Si=,BecausetheAEPSCCookNuclearPlantisadualunitplant,specialattentionwaspaidtotheconsiderationofdualunitissues.TheinteractionsofthetwoCookNuclearPlantunits'ystemsweremodeledexplicitly.Incertaincases,conservativeassumptionsweremadeinconductingthedualunitanalysisinordertoprovideaperspectiveoftheentireplant'sresponse.Theanalysiswasperformedinamannersuchthatthesystemsandresourcesatoneunitmayplayakeyroleinmanagingtheresponsetoanaccidentaffectingitscompanionunit.n.'Specialattentionwasalsopaidtotheinterfacebetweenthetraditionalsystemsanalysisandcontainment'systemsanalysisportionsoftheIPE.Properintegrationoftheseportionsoftheanalyseswasbasicallyaccomplishedthroughtheestablishmentoftheeventtreeswhereinbothsystemperformanceandoperator1-2 actionsthataffectedLevelIandIIresultsweremodelled.ThetreestructuresandtheuseoftheMAAPcodeallowedproperinterpretationandassessmentofvariousrecoveryoptions.Keysuccesscriteriaandtimingwereestablishedwiththesetools.1.4SummaryofMajorEndingsThissectionsummarizesthemajorfindingsoftheCookNuclearPlantPRA.First,theresultsofthecoredamagefrequencyquantificationarepresented.Second,thedominantcontributorsleadingtocoredamageforsignificantinitiatingeventsaredescribed.,Thecontainmentfailurefrequencyandmechanismarethendescribed.Finally,theoffsitedoseconsequencesarereviewed.ThecoredamagefrequencyfortheCookNuclearPlantwasfoundtobe6.26E-5peryearconsideringinternal.initiatingevents,includinginternalflooding.ThisvalueissimilartotheresultsofotherPRAsforsimilarlydesignedplants(Reference66.)Fortheinitiatingeventswiththelargestcontributiontothecoredamagefrequency,thedominantsystemfailurecontributorsaredescribed.Theorderinwhichtheinitiatorsarepresentedinthissectionrepresentstheirdescendingcontributiontooverallcoredamagefrequency.Theinitiatingeventwiththelargestcontributiontocoredamagefrequencyat2.96E-SperyearwasfoundtobeSmallLOCA(SLO).FailureoftheEmergencyCoreCoolingSystem(ECCS)duringeitherthecoldlegirjectionorrecirculationphasesproducedthetwodominantsequencesforthisevent.Inturn,commonmodefailureofthesafetyirjection(Si)pumps(partoftheECCS)andfailureoftheEngineeredSafetyFeatures(ESF)systemtoactuatetheECCSdominatedthesetwosequences.Thethirdleadingsequencewasafunctionalfailuretocoolthereactorcoolantsystem(RCS)followedbyfailureofprimarybleedandfeedcooling.Hardwareandcommonmodefailuresinthecompressedairsystem,whichsuppliesairtothepressurizerandsteamgeneratorpressurereliefvalves(PORVs),weretheprimarycontributorstothesefailures.TheLossofComponentCoolingWater(CCW)event,withacoredamagefrequencycontributionof1.38E-5peryear,wasdominatedbythreesequences.Thefirstsequencewassolelydominatedbythefailureoftheoperatortotriptherunningreactorcoolantpumps(RCPs)aftersealcoolingfromCCWislost,thusleadingtogrosssealfailure.ThesecondsequencewasdominatedbyfailureofECCScoldlegrecirculationduetocommonmodefailureoftheSIpumps.ThethirdsequenceinvolvedthefunctionalfailuretorestorereactorinventoryafterCCWwasrestored(whichallowsrestorationoftheECCSchargingpumps).ThislatterfailurewasdominatedbyoperatorerrorandESFsignalfailure.ThecoredamagefrequencyinitiatedbyaSteamGeneratorTubeRupture(SGR)was7.07'eryearanditconsistedofseveralsignificantsequences.ThedominantfailuresassociatedwiththesesequenceswerehardwareandcommonmodefailuresofthecompressedairsystemandfailuresofESFsignals.Thiseventisparticularlysignificancesincecontainmentmaybebypassedandfissionproductsreleaseddirectlytotheenvironment.Allotherinternalinitiatingeventswereverysmallcontributorstotheoverallcoredamagefrequency,anddisplayednosignificantvulnerabilitiesinadditiontothosepreviouslydiscussedinthissection.Theredundancyaffordedbytheauxiliaryfeedwatersystem(twomotor-drivenpumpsandoneturbine-drivenpump)wassignificantlybeneficialforthetransientevents.Theextremelyreliableelectricpowergrid,ofwhichCookNuclearPlantisapart,greatlyinfluencedtheinitiatingeventfrequenciesfortheLossofOffsitePowerandStationBlackoutevents,thusdirectlyinfluencingtheirsmallcontributionstocoredamagefrequency.Evaluationofthesuccesscriteriausedintheeventtreeanalysisshowedthatcontainmentfailurecouldoccurpriortocoremelt.ItwasalsofoundthatECCSflowandsecondaryheatremovalcanpreventorsubstantiallydelaycontainmentfailureinthosesequenceswherecoremeltispreventedregardlessofwhethercontainmentspraysareoperatedornot.=q'>>5.1-3 Theoverallfrequencyofcontainmentfailure,whichincludesisolationfailuresandcontainmentbypass,wasfoundtobesmallat9.1~peryear.Giventhatacoremeltaccidenthasoccurred,thereisapproximatelyan85%chancethatcontainmentintegritywillbemaintained.Failureofthecontainmentduetoslowoverpressurizationcausedbysteamingwasfoundtooccuronly3.3%ofthetimefollowingcoredamage,withtherestofthecontainmentfailuresinvolvingcontainmentbypasssequences.Itisimportanttonotethatcontainmentoverpressurizationfailuredoesnotoccurifcontainmentsprayinjectionandrecirculationareavailable.Ofthebypasssequences,onlysteamgeneratortuberupturesoccurwithsufficientfrequencyandsourcetermtobeconsideredimportant.Failureofcontainmentduetohydrogengenerationandcombustionwasfoundtobeunlikelyevenforthose'aseswhereallpowerwaslosttothehydrogenigniters.Evenforatotalstationblackout,theworstsequencewithrespecttohydrogenaccumulation,itwasfoundtobeunlikelythatsufficienthydrogencouldaccumulatetochallengethecontainmentultimatepressure.Containmentfailureduetooverpressurizationisexpectedtooccurduetoshearfailureoftheconcreteatthecylinderwallibasematjunction.Thisfailuremechanismisbelievedtobesuchthatveryfewaccidentmitigationactionswouldbepossibleafterfailureduetotheinabilitytomaintainwaterinventoryinsidethecontainment.Becausea~,.identmitigationandrecoveryactionswouldbeverylimited,thelongtermconsequencesofthisfailu;;~ouldbesevereandpreventionofthisfailureisconsideredveryimportant.UsingcontainmentatmosphericreleasesourcetermsfromtheLevelIIanalysis,offsiteconsequenceswerecalculatedusingtheMELCORAccidentConsequenceCodeSystem(MACCS).TheshorttermoffsiteconsequencesofthedominantsequencesfromtheLevelIIanalysiswereaddressedconsideringthreeemergencyplanningscenarios(evacuationto10miles,noevacuation,andevacuationto2mileswithshelteringfrom2to10miles).Inaddition,MACCSwasusedtodeterminethelongterm(chronic)affects.TheSGR50sequence(steamgeneratortuberupture)sourcetermsdominateearlyandcancerfatalitiesandwholebodydoses.SGR50isacontainmentbypasssequenceforwhichthecontainmentalsofailsonoverpressure.Virtuallyallofthenoblegasesand>10%ofthevolatilefissionproductsarereleasedfromcontainmentinthisscenario.Anemergencyoperatingprocedurechangeisbeinginvestigatedforthissequencetomaintainwaterlevelintheaffectedsteamgeneratorinthecaseofatuberupture.Thisisexpectedtogreatlyreducetheoffsitedoseconsequencesofthissequence.TheCookNuclearPlantPRAwasdevelopedtomeettherequirementsof10CPR50AppendixB.ThisapproachforceddetailedreviewbeyondthataddressedinGenericLetter88-20(Reference9).AEPSCisconfidentthatthisanalysisadequatelymeetstheintentofGenericLetter88-20,includingSupplements1and3.Nomajorplantvulnerabilitieshavebeenidentifiedwhichrequireimmediateactionorsignificanthardwarechanges.Changestobothproceduresandhardware,however,arebeingconsideredtoaddressminor.vulnerabilities.TheseareidentifiedinSection6.0.

2.0RVGQHINATIONDESCRIPTION2.1IntaxhxtioaTheCookNuclearHantIPEhasbeenperformedtoidentifyandresolveplantspecificsevereaccidentissues.Inaccomplishingthistask,AEPSChasperformedafullscopeLevelIIIPRA.AEPSChasconductedthePRAinfullcompliancewiththerequirementsoftheNRCGenericLetter88-20,includingSupplements1and3.AEPSC'sapproachtotheIPEhasbeentoperformrealisticevaluationsofCookNuclearPlant'scapabilities,withemphasisonthepreventionofsevereaccidentsandontheneedtoeffectivelyrespondtoaccidentsequenceprogressionintheeventofasevereaccident.AEPSC'sevaluationswerealsocarriedoutinamannerthatsupportsdecisionsregardingpotentialenhancementstoplantdesignand/oroperationaimedatreasonable,cost~ectivereduction,ofriskfromsevereaccidents.TheCookNuclearPlantInternalEvents(LevelIPRA)Programconsistedofthefollowing12majortasks:1.ProjectManagement2.DataAnalysis3.InternalInitiatingEventAnalysis4.EventTreeAnalysis5.SystemsAnalysis6.SystemsInteraction7.HumanReliabilityAnalysis8.InternalFloodingAnalysis9.FaultTreeandAccidentSequenceQuantification10.RecoveryActions11.SensitivityandImportanceAnalysis12.TrainingandTechnologyTransferTheCookNuclearPlantContainmentPerformanceAnalysis(LevelIIPRA)Programconsistedofthefollowingfourmajortasks:1.2.3.ContainmentSystemsAnalysisContainmentStructuralCapabilityReviewContainmentEventTreeAnalysisSourceTermAnalysisTheCookNuclearPlantOffsiteConsequencesAnalysis(LevelIGPRA)Programconsistedofthefollowingthreemajortasks:1.SiteModelDevelopment2.OffsiteConsequencesAnalysis3.ConsequenceEstimationThemodelsdevelopedintheIPErepresenttheas-built,as-operatedCookNuclearHant.Effortsweretakentoensurethatformalproceduresforwhichtheoperatorsweretrainedtousehavebeencredited.Inaddition,operatorinterviewswereconductedtodeterminewhencreditcouldbetakenfortheknowledgegainedbyoperatorsthroughtheirdailyactivities.Thevalueofequipmentorproceduralimprovementsandinsightswereinvestigatedthroughsensitivitystudies.2-1 22ConforxnancewithGenericLetterandSupportingMaterialGenericLetter88-20requestedeachutilitytoperformanIndividualPlantExaminationforthepurposeof:(1)developinganappreciationofsevereaccidentbehavior,(2)understandingthemostlikelysevereaccidentsequencesthatcouldoccuratitsplant,,i(3)gainingamorequantitativeunderstandingoftheoverallprobabilitiesofcoredamageandfissionproductreleases,andifnecessary,(4)reducingtheoverallprobabilitiesofcoredamageandfissionproductreleases.GeneralrequirementsprovidedintheGenericLetterforfulfillingthestatedpurposewere:(1)TheutilitystaffshouldbeusedtothemaximumextentpossibleintheperformanceoftheIPEtoinsurethatthey:~understandtheplantprocedures,design,operation,maintenanceandsurveillance,~understandthequantificationoftheexpectedsequencefrequencies,~determinetheleadingcontributorstocoredamageandunusuallypoorcontainmentperformance,~identifyproposedplantimprovementsforpreventionandmitigation,~examineeachoftheproposedimprovements,and~identifywhichproposedimprovementswillbeimplementedandtheirschedule.(2)Theutilityshouldproceedwiththeexaminationofinternallyinitiatedeventsincludinginternalflooding.~;(3)ThemethodofexaminationshouldeitherbeaPRAthatfollowsthePRAproceduresdescribedinReferences25,26and29,plusacontainmentperformanceanalysisthatfollowstheguidanceofAppendix1toGenericLetter88-20ortheIndustryDegradedCore(IDCOR)frontedmethodwithNRCenhancements,oranothersystematicmethodthatisacceptabletothestaK(4)TheutilityshouldresolveUnresolvedSafetyIssue(USI)A45,"ShutdownDecayHeatRemovalRequirements,"aspartoftheIPE.(5)TheutilityshouldcarefullyexaminetheresultsoftheIPEtodetermineifthereareworthwhilepreventionormitigationmeasuresthatcouldbetakentoreducethefrequencyofcoredamageorimprovecontainmentperformance.(6)TheutilityshouldreporttheresultsoftheIPEtotheNRCconsistentwiththecriteriaprovidedintheGenericLetterandsubsequentguidanceprovidedinReference20.(7)Theutilityshoulddocumenttheexaminationinatraceablemannerandretainitforthedurationofthelicenseunlesssuperseded.(8)Theutilityshouldconductfutureevaluationsforaccidentmanagementandexternaleventswhentheguidanceforthemhavebeendeveloped.2-2 InresponsetotheGenericLetter,AEPSCissuedaletteronOctober24,1989statingitsintenttoperformafullscopeLevelIIIPRAconsideringbothinternalandexternaleventsfortheCookNuclearPlantinordertoidentify,evaluate,andresolvesevereaccidentissuesgermanetotheplant.AEPSChasinvestedsubstantialpersonneltime(inexcessof23,000man-hours)inadditiontofinancialresourcesfortheeffortsofacontractor(IndividualHantEvaluationPartnership)intheperformanceofanIPEthatmeetsorexceedstheNRCdirectiveslistedinGenericLetter88-20.Apermanentlyassignedcorestaff,knowledgeableinthedesignandoperationoftheCookNuclearPlant,hasbeeninvolvedinallaspectsoftheIPE.OtherAEPSCpersonnelhavebeenintensivelyinvolvedinvariousaspectsoftheevaluationasneeded.Inaddition,asubstantialtrainingeffortwasundertakentoinsurethatAEPSCpersonnelwhohadaneedforunderstandingoftheevaluationorpartsthereofdevelopedanappreciationfortherisksignificanceoftheresultsandtheplantresponseandanunderstandingofthebasesoftheIPE.Finally,*AEPSChasandiscontinuingtoreviewtheresultsoftheIPEforareaswhereplantimprovementscanbeeffectivelymadetoreducethelikelihoodofcoredamage.TheseeffortsarebeingmadedespitethefindingsthattheoverallresultsoftheCookNuclearPlantIPEindicatethatthecoredamagefrequencyandcontainmentperformancearewithintheexpectedlimits.2QGeneralMethodologyTheCookNuclearPlantIPEprogram,aspreviouslyidentified,consistedof19majortaskscovering'thefullscopeLevelIIIPRA.TheIPEwasconductedusingstandardsystemsanalysispracticessuchasthoseoutlinedinReferences25and26.AcomprehensivetaskbreakdownwasdevelopedfortheCookNuclearPlantPRAinordertoorganizetheworktobeaccomplished.Anoverviewofeachofthetasksisprovidedbelow.Guidebookinstructionsweredevelopedforeachofthekeytechnicaltasks.LevelIPRATasks1.ProjectManagement-Developmentandmonitoringofdetailedprojectplanningandschedulingprovidednecessarytechnicaldirectionofprojectanalysesandproperreviewofresults.2.DataAnalysis-Plant-specificinformationwascollectedfromavarietyofjoborders,controlroomlogs,andcompletedsurveillancetestproceduresfortheperiodfromJanuary1,1983toAugust1,1989toidentifyandexamineplantwpecificcomponentfailure,testing,andmaintenancedataanddatarelatedtoinitiatingeventsthathaveledtoreactortrips.MostofthedatausedintheCookNuclearPlantPRAutilizedplant-specificdatatocalculatefailureratesthroughclassicalmeansorthroughtheuseofBayesiantechniques.Insomeinstances,genericdatafromIEEE-500,"IEEEGuidetotheCollectionandPresentationofElectricalElectronicSensingComponentandMechanicalReliabilityDataforNuclearPowerPlantGeneratingStations"(Reference11),Reference29orothersourceswereusedtosupplementplantdata.3.InternalInitiatingEventsAnalysis-TheselectionofaccidentinitiatingeventsfortheCookNuclearPlantPRAconsideredbothactualplanttripdataandresultsofpreviousPRAs.CookNuclearPlanttripdatawascollectedfromscramreportsandplantcontrolroomoperatinglogstoidentifyactualtripevents,powerlevelatwhichthetripoccurred,andthefailurewhichcausedthetrip.TheCookNuclearPlantaccidentinitiatingeventsalsoincludedlargeLOCA,mediumLOCA,smallLOCA,steamgeneratortuberupture(SGTR),lossofoffsitepower,stationblackout,steamline/feediinebreaks,ATWS,andtransients.Mosttransientinitiatorswereevaluatedaseitherwithorwithoutthepowersteamconversionsystembeingavailable.Specialinitiatorsthatwereconsideredincludedlossofessentialservicewater,lossofcomponentcoolingwater,lossofcontrolair,lossof120VACandlossofa250VDCbus.2<<3 Severalmethodswereemployedtodetermineinitiatingeventfrequenciesfortherelevantinitiators.ForthoseeventshavingsufficientCookNuclearPlantdata,eacheventwascategorizedasidentifiedaboveandthefrequencydeterminedbythenumberofoccurrencesofeacheventinthecategory.ForeventssuchasLOCAs,theinitiatingeventfrequencywasdevelopedfromgenericdataorfromtheresultsofpreviousPRAsorsimilarlydesignedplants.Asanexample,thesmall,medium,andlargebreakLOCAinitiatingeventfrequenciesweretakenfromWASH-1400,"ReactorSafetyStudy:AnAssessinentofRisksinU.S.CommercialNuclearPowerPlants"(Reference36).LossofoffsitepowerwasdeterminedfromadetailedstudyoftheAEPSCgridreliability,andSGTRwasdeterminedfromtheWestinghouseplantpopulationexperiencedatabase.Theinitiatingeventfrequencyforthespecialinitiatorswasdeterminedthroughplantspecificfaulttreeanalysis.y)EventTreeAnalysis-Plant-specificeventtreemodelsweredevelopedforeachaccidentinitiator.Thistaskincludedthedefinitionofcriticalsafetyfunctionsrelevanttotheinitiatingevents,developmentofsystemleveleventtreesandsystemsuccesscriteriaforthevariousaccidentsequences,andincorporationofoperatoractionsandconsequentialfailuresrelatedtovariousaccidentsequences.SystemsAnalyses-TheCookNuclearPlantsystemsweremodeledwithfaulttrees.Foreachsystem,thecompletesystemanalysisincludedthedevelopmentofdetailedsystemnotebooksdescribingthesystem,itsoperation,theeffectofaccidentconditions(successcriteria,initiatorimpact,etc.),itsoperatinghistory,thesystemmodelsandassumptions,quantiTication,andanalystinsights.Therelationshipbetweenthetwounitsanddifferencesinsystemdesignswerealsocarefullyexaminedandnoted.Thedevelopmentofthefaulttreemodelswasdonefromthetopeventdown.Faulttreedevelopmentwasaccomplishedthroughthegenerationofsimplifiedflowdiagramsandfaulttreemoduleswhichsimplifiedandstandardizedthefaulttreelayouts.ThefaulttreesweredevelopedandquantiTiedusingtheWestinghousefaulttreeGRAFfERCodeSystem(Reference10).Thefaulttreemodelsincorporatedequipmentfailure,test,maintenance,humanreliabilitymodeling,andcommoncauseanalysiswhereappropriate.AstheCookNuclearPlantPRAutilizedthefaulttreelinkingapproachtoquantification,theappropriatesupportsystemsarealsoincludedinthefaulttreemodels.SystemsInteraction-Possiblesysteminteractionswereidentifiedbyconductingdetailedsystemwalkdowns,acontrolroomevaluationandinterviewswithplantoperators.Adependencymatrixwasalsodevelopedtoidentifytheinteractionsbetweenfront-lineandsupportsystems.HumanReliabilityAnalysis-Detailedmodelsweredevelopedtorepresenttheinteractionofoperatorsandotherplantstaffwithplantsystemsandequipmentduringnormaloperationandduringtransientandaccidentconditions.TheTechniqueforHumanErrorRatePrediction(THERP)methodology(Reference22)wasusedforthehumanreliabilityanalysis.InternalFloodAnalysis-AseparateanalysiswasperformedtodetermineareasintheCookNuclearPlantthataresusceptibletoflooding,equipmentinthoseareaswhosefailurescouldcauseaplantshutdownorresultinafailedsafetysystem,andthecontributiontocoredamagefromfloodingofthoseareas.Theappropriateeventtreesfromtheotherinternaleventinitiatorswereusedtoquantifythecontributionoffloodingtocoredamagefrequency.FaultTreeandAccidentSequenceQuantiTication-TheCookNuclearPlantsystemfaulttreesandeventtreeaccidentsequenceswereintegratedandquantifiedtoobtainaccidentsequencecutsets,frequenciesforallaccidentsequencesresultingincoredamage,andtoidentifydominantaccidentsequencesamongalleventtreeresults.TheWestinghouseWLINKCodeSystem(Reference46)wasusedtoperformtheaccidentsequencequantification.ResultsofthisanalysisaretheessentialdatainputtotheLevelIIPRA.

10.RecoveryActions-RecoveryactionswereidentiTiedandtheirrespectivefailureprobabilitiesquantified.SensitivityandImportanceAnalyses-Theresponseofthecoredamagefrequencytochangesininputparametersandmodelingassumptionsforthecoredamagefrequencydominantcontributorswasexaminedtoidentifyimportantactionsandequipmentandtostudythesensitivitytothoseassumptions.12.TrainingandTechnologyTransfer-Trainingwasconductedbycontractoremployeesforutilitypersonneltoprovidethein-houseabilitytounderstand,evaluate,modify,andupdatethePRAstudytoreflectproposedoractualchangesintheplantdesignandoperation.TrainingincludedinitialorientationtoPRAtechnology,trainingsessionsoneachmajortask,anddiscussionofanalysis-specificguidebooks.LevelIIPRATasksContainmentSystemsAnalysis-QuantitativemodelsforcontainmentsystemsfailuresandcontainmentbypasseventsweredevelopedandquantifiedaspartoftheLevelIPRA.TheresultsoftheseanalysesprovideinformationforuseintheLevelIIanalysisregardingthestateoftheplantsystems,thephysicalstateofthecore,andthereactorcoolantsystem.Amodelforfailureofcontainmentisolationwasdevelopedandquantifieindependentlyoftheothermodels.Thefailureprobabilityofcontainmentisolationwasusedforthecontainmenteventtreequantification.2.ContainmentStructuralCapabilityReview-Existingandupdatedstructuralanalyseswereusedtodeterminethecontainmentultimatepressurecapabilityandpotentialfailurelocations.3.ContainmentEventTreeAnalysis-Acontainmenteventtree(CET)wasdevelopedtoprovideasystematicmethodforintegratingtheLevelIresultswiththeLevelIIanalysis.TheCETdescribesthecontainmentresponsetoacoremeltaccidentandaccountsforsysteminteractions,operatoractions,andkeyphenomenologicalissuesbydefiningafunctionalsetoftopeventsandtheirsuccessandfailurestates.4,SourceTermAnalysis-SourcetermsweredevelopedbyanalyzingthedominantaccidentsequencesthatledtocontainmentfailureusingtheMAAPcode(Reference13).Sourcetermswerebinnedintoreleasecategoriesbasedonthetype,timing,andmagnitudeoftherelease.LevelIIIPRATasksSiteModelDevelopment-ACookNuclearPlantsitemodelwasdevelopedusingavailableinformationonthedemographyandmeteorologyintheregionoftheCookNuclearPlantsite.2.OffsiteConsequencesAnalysis-TheoffsiteconsequencesassociatedwitheachofthefissionproductreleasecategoriesidentiTiedinthesourcetermanalysisweredeterminedusingtheMACCScomputercode(Reference14).TheMACCScomputercodeoutputsusedintheanalysisincludedacutefatalities,latentfatalities,andtotalpopulationexposure.Theanalysisaccountedforemergencyactionplans,includingevacuation,sheltering,anddecontamination.3.ConsequenceEstimation-Theoffsiteconsequencesforthethreeidentifiedoutputs(acutefatalities,latentfatalities,andtotalpopulationdose)weredevelopedbasedonmultipleatmosphericdispersionanalysesandpresentedintheformofcomplementarycumulativedistributionfunctions,whichshowedagraphicalrepresentation.Theanalysesyieldedtheexpectedconsequencelevelandtheprobabilityofexceedingthatlevel.Theestimatedprobabilitieswerebasedontheassumptionthatthereleasehadoccurred.Therefore,theactualprobabilityofoffsiteconsequenceisequaltothecontainmentreleaseprobabilitytimestheconsequenceprobability.2-5 2.4InformationAssemblyAtremendousamountofinformationwasneededtoperformthedetailedCookNuclearHantIPEstudy.Theprojectteamreviewedandassembledinformationfromplant,specificsources,similarplantstudies,andgenericsources.Hantwalkdownswereapart,ofthedatacollectioneffort.Informationwasassembledtofamiliarizetheanalystwiththeplant,determinetheimportantinitiatingeventsandquantifytheirfrequency,determinethecomponentandsystemfailurerates,performvarioussupportinganalyses,conducttheevaluationofinternallyinitiatedfloodingevents,anddevelopplantlayoutinsightsthroughtheuseofplantwalkdowns.Walkdownswerespecificallyusedtosearchforplantcharacteristicsthatcouldimpactthetransportofradionuciidesinthecontainmentandauxiliarybuilding.Table24-1providesalistoftheimportantsourcesofinformationthatwerereviewedfortheLevelIanalysis.ThecompletelistsofallindividualreferencesusedaredocumentedintheCookNuclearHantIPEprojectnotebooks.~:TheCookNuclearPlantIPEteammodelledtheCookNuclearHantas-builtconditionasitexistedonAugust1,1989.NomajorchangestoplantoperationordesignhavebeenidentifiedsinceAugust1,1989,thatwouldbeexpectedtosignificantlyaffectthePRAresults.Muchoftheinformationwascollectedattheoutsetoftheproject.AllinformationusedintheprojectisavailableattheAEPSCofficesinColumbus,Ohio.CopiesofsomeinformationarealsohousedattheWestinghouseofficeinMonroeville,PAandtheFauskeandAssociates(FAQofficeinBurrRidge,Illinois.Detailedsystemnotebooksweredevelopedfor14moorsystemsandseveralmiscellaneoussystemsthatwereexpectedtohaveaninfluenceontheCookNuclearPlantIPEresults.Inaddition,notebooksweredevelopedformajoranalysesoftheIPEproject(e.g.,initiatingevents,internalflooding,etc.).HantinformationsourcesidentifiedinTable2.4-1wereusedtodevelopsystemdescriptionsandmodels.Bothplantspecificandgenericsourcesidentifiedwereusedtodefinecomponentavailabilities,initiatingeventsandinitiatingeventfrequency,importantaccidentsequences,potentiallyimportantmodelingfeatures,commoncausefailurerates,andhumanreliabilitydata.Subsequentsectionsofthisreportprovideamoredetaileddiscussionoftheuseoftheinformationcollected.0'lantwalkdownswereconductedbyallmembersoftheAEPSCIPEteamandsomerepresentativesfromtheIPEPteamwhowereresponsiblefortheevaluationofaspecificplantsystem,thecontainmentand/oritssystems,ortheevaluationofinternalflooding.ThewalkdownteamswereledbyCookNuclearPlantpersonnelwhowereknowledgeableabouttheplantsystemsandthecontainmentandtheirdetailedarrangement.WalkdownswereconductedforthesystemsandplantenvironmentofmostconcerntothePRA.TheseareasarecontainedprimarilyintheAuxiliaryBuildingandtheContainment;however,severalotherbuildingsorareaswereexaminedbecauseimportantsystemsandcomponentsarelocatedtherein.Theareasorbuildingsinwhichwalkdownsweremadeare:eContainment~AuxiliaryBuilding~TurbineBuilding~ServiceWaterScreenHouse~ControlRoom~OutsideGroundsIncludingSwitchyardsGeneralarrangementdrawingsoftheseareasarecontainedintheUFSAR.Oi ThewalkdownsthatwereconductedduringtheIPEprojectaresummarizedbelow.SystemWalkdowns-TheAEPSCsystemfaulttreeanalystsconductedinitialwalkdownsofthesystemsmodelledwithintheCookNuclearPlantPRAfromMarch13toMarch15,1990.WalkdownswereconductedinUnits1and2.CookNuclearHantoperationspersonnelassistedtheteaminbecomingfamiliarwithequipmentlocations,systemoperations,andtest/maintenancepractices.ContainmentWalkdowns-ThePRAteammembersassignedtotheContainmentPerformanceAnalysistaskperformedacontainmentwalkdownoftheUnit1containmentonJuly16and17,1990,toverifythatthephenomenologicalmodelsaccuratelyreflectedtheconditionoftheplant.Inaddition,containmentisolationcapabilityandpotentialcontainmentbypassfiowpathswerealsoexaminedforUnits1and2bywalkdownsoftheAuxiliaryBuildingduringthistime.OperatorInterviews-Theexecutionofthehumanreliabilityanalysisinvolvedboththeidentificationandevaluationofplantproceduresandadiscussionofthepertinentstepsthereinwithplantoperators.Theinterviews,whichwereconductedonMarch14and15,1991,providedtheanalystswithinsightsintothecomplexityofthetasks,thefamiliarityoftheoperatorswiththerequiredtasksteps,thetimeconstraintsinvolved,andtheextentoftrainingconductedbytheplant.Theanalystsdirectlyinvolvedinthehumanreliabilityanalysisperformedtheinterviews.InternalFloodingWalkdown-WalkdownswereperformedonMarch13through15,1990,andJuly18and19,1990,primarilytogainanunderstandingofthespecialrelationshipsofcomponentsandequipmenttothevariousspecifichazardspresentedbyinternalfloodingsources.Analystsassignedtothistaskweretheprimaryparticipantsinthesewalkdowns.2-7 Table2.4-1CookNuclearPlantIPEInformationSources~PlantSecifiDonaldC.CookNuclearHantUpdatedFinalSafetyAnalysisReport,AmericanElectricPowerServiceCorporation,July1989.(Reference1)DonaldC.CookNuclearPlantUnits1and2TechnicalSpecifications,DonaldC.CookNuclearHant,AmericanElectricPowerServiceCorporation,Amendment127Unit1,Amendment113Unit2.(References2and3)DonaldC.CookNuclearPlantUnits1and2SystemDescriptions,AmericanElectricPowerServiceCorporation.PlantSystemFlowDiagrams.PlantArrahgementDrawings.PlantElectricalOne-LineDiagramsandElementaryDiagrams.EmergencyOperatingProcedures.NormalOperatingProcedures.MaintenanceProceduresSystemSurveillanceTestProceduresDonaldC.CookNuclearPlantFacilityDataBase.OlDonaldC.CookNuclearPlantSetpointDocument.NuclearTestSchedule,DonaldC.CookNuclearHant,AmericanElectricPowerServiceCorporation,September1989.AEPSCCalculations.DonaldC.CookControlRoomLogsDonaldC.CookJobOrderRecords Table24-1CookNuclearHantIPEInformationSources(Cont'd)$01~(EnrluNUREG-1032,EvaluationofStationBlackoutAccidentsatNuclearPowerPlants,June1988.(Reference19)NUREG/CR-1174,"EvaluationofSystemInteractionsinNuclearPowerHants,"August1989.(Reference21)NUREG/CR-1278,"HandbookforHumanReliabilityAnalysiswithEmphasisonNuclearPowerPlantApplications,"August1983.(Reference22)NUREG4909,"January25,1982SteamGeneratorTubeRuptureatR.E.GinnaNuclearPowerHant,"April1982.(Reference18)NUREG/CRP142,"AReviewoftheMillstone3ProbabilisticSafetyStudy,"April1986.(Reference28)WASH-1400,"ReactorSafetyStudy:AnAssessmentofRisksinU.S.CommercialNuclearPowerPlants,"-October1975.(Reference36)NUREG/CR-2300,"PRAProceduresGuide,"January1983.(Reference26)NUREG/CR-2678,"FloodRiskAnalysisMethodologyDevelopmentProjectFinalReport,"June1982.(Reference23)NUREG/CR-2815,"ProbabilisticSafetyAnalysisProcedureGuide,"Rev.1,August1985.(Reference25)NUREG/CR-3862,"DevelopmentofTransientInitiatingEventFrequenciesforUseinProbabilisticRiskAssessments,"EG&GIdaho,Inc.,May1985.(Reference27)NUREG/CR4550,"AnalysisofCoreDamageFrequencyfromInternalEvents,"Volumes14,September1987.(Reference29)'tNUREG/CR4780,"ProceduresforTreatingCommonCauseFailuresinSafetyandReliabilityStudies,"Volume1,February1988andVolume2,January1989.(Reference30)EPRINP-3967,"ClassificationandAnalysisofReactorOperatingExperienceInvolvingDependentEvents,"June1985.(Reference7)EPRINP-3583,"SystematicHumanReliabilityProcedure(SIIARP),"June1984.(Reference5)NSAC-144,"LossofOffsitePoweratU.S.NuclearPowerHants,"April1989.(Reference17)NSAC-108,TheReliabilityofEmergencyDieselGeneratorsatU.S.NuclearPowerHants.(Reference16)IEEE-500,IEEEGuidetotheCollectionandPresentationofElectricalElectronicSensingComponentandMechanicalEquipmentReliabilityDataforNuclearPowerGeneratingStations.(Reference11)IDCORTechnicalReports.

Table24-1CookNuclearPlantIPEInformationSources(Cont'd)0)~SQR~EINFOSOER85-5,"InternalFloodingofPowerPlantBuildings,"December1985.(Reference12)NUREG/CR-5536,"MitigationofDirectContainmentHeatingandHydrogenCombustionEventsinIceCondenserPlants,"October1990.(Reference31)EPRINP-3878,"LargeScaleHydrogenCombustionExperiments,"October1988.(Reference6)WtinhWWCAP-11902,"ReducedTemperatureandPressureOperationforDonaldC.CookNuclearPlantUnit1LicensingReport,"October1988.(Reference41)WCAP-12078,"InputandOutputParametersfortheAccidentAnalysesPerformedforReducedTemperatureandPressureOperationforDonaldC.CookNuclearPlantUnit1,"December1988.(Reference43)WCAP-9600,"ReportonSmallBreakAnalysisforWestinghouseNSSSSystems,"Volume1,June1979.(Reference37)WCAP-12135,"DonaldC.CookNuclearPlantUnits1and2,ReratingEngineeringReport,"September1989.(Reference44)WCAP-10541,"ReactorCoolantPumpSealPerformanceFollowingaLossofAllACPower,"Rev.2,November1986.(Reference39)~:)WCAP-11992,"JointWestinghouseOwnersGroup/WestinghouseProgram:AssessmentofCompliancewithATWSRuleBasisforWestinghousePWRs,"December1988.(Reference42)WCAP-10858-PA,"AMSACGenericDesignPackage,"Rev.1,July1987.(Reference40)WCAP-9914,"PORVSensitivityStudyforLOFW-LOCAAnalyses,"July1981.(Reference38)2-10 2STmdmeutofDualUnitsTheCookNuclearPlantisadualunitsite.BothunitsareWestinghousefour-looppressurizedwaterreactorswithicecondensercontainments.Unit1wasexplicitlyanalyzedintheCookNudearHantIPE.BothunitswereexaminedandtheUnit1analysiswasdeterminedtobeboundingforUnit2.Themulti-unitmethodologyusedfortheCookNudearHantIPEconsistedoffivekeyanalysisareas.Theseareaswere:1)plantfamiliarization,2)initiatingeventanalysis,3)supportsystemanalysis,4)frontlinesystemanalyses,and5)containmentanalyses.PlantfamiliarizationinvolvedthecollectionandevaluationofplantdocumentationonthedesignandoperationofeachunitandidentiTicationofdependenciesbetweenfrontlinesystemsandsupportsystems.Plantwalkdownswereconductedtosupporttheplantdocumentationreviewandtolookfordependenciesandotheras-builtinformationthatwasnotevidentfromtheplantdocumentation,indudingdifferencesintheconfigurationofthesamesystemsinthedifferentunits.NodifferenceswhichwouldhavehadanimpactintheIPEresultswereidentified.Datacollectedtodeterminetherelevantinitiatingeventsandthesystemdependencieswereexaminedtoidentifyintersystemdependenciesbetweenunitsthatcouldresultfromparticularinitiators.Nointer-unitdependencieswereidentifiedwhichwouldhavehadanimpactontheinternalinitiatingeventsanalysis.Supportsystemsweremostcrucialindeterminingthecorrectplantresponsetoaninitiatingeventbecausesomesupportsystemsaresharedorhavethepotentialtobecrossconnectedbetweenunits.TheAEPSCmethodforcapturingtheeffectsofthesecondunitofCookNuclearPlantwastodevelopfaulttreemodelsforthesharedsupportsystems.Thesefaulttreemodelswereexplicitlyindudedintheoverallaccidentsequencequantificationthroughfaulttreelinking,Frontlinesystemsanalysesusedacomparativemethodforthosesystemsthatwerefoundtobecompletelyindependentbetweenunits,whilethosesystemsthatwerefoundtobesharedorpartiallysharedweremodeledtoincludeallcomponentsofthesystemorsystemstotheextentofinfluence.Forthefrontlinesystems,adetailedcomparisonofthetwounitswa'smadetoidentifythedifferencesandcommonalities.NodifferenceswhichwouldhavehadanimpactontheIPEresultswereidentified.Afinalstepinthedualunitmethodologyresultedintheexaminationoftheeventtreesdevelopedforthefirstunittodeterminewhetheranydifferencesidentifiedinthereviewofthesecondunitwouldcausedifferentoradditionaleventstobenecessarytoaccuratelyrepresentthesecondunit.Nosignificantdifferenceswerefound.Finally,thelevel2analysiswhichwasconductedforUnit1wasfoundtobeboundingforUnit2.Insummary,theCookNudearPlantIPEanalyzedthedesignandoperationofUnit1.Unit2wasexaminedandnodifferencesfromUnit1wereidentifiedwhichwouldhaveimpactedtheIPEresults.TheIPE,therefore,maybeappliedtoeitherunit.2-11 3.0FRONT-ENDANALYSIS3.1AccidentSequenceDelineation3.1.1InitiatingEventsAllinternalinitiatingevents,indudinginternalflooding,analyzedintheCookNudearPlantIPEarelistedinTable3.1-1.Internalinitiatingeventscausesequencesofeventsthatcanresultininsufficientcorecooling.Insufficientcorecoolingcanbecausedbyeitheralossofprimarycoolant(LOCA)orinsufficientheatremovalbysecondarysidesystems.Amoredetaileddiscussionofthegroupingofinitiationeventsfollows.3.1.1.1LossofCoolantAccidentsThegeneralcategoryofinitiatingeventsreferredtoasLOCAsincludesallaccidentsthatresultinareductionofprimarycoolantsystemwaterinventory.Thiscategoryofeventswasfurtherdividedintosubcategoriesonthebasisoftheleakpathandsize.Thesesubcategoriesaredescribedbelow.3.1.1.1.1LargeLOCAThelargeLOCAcategoryincludesrupturesinsidecontainmentinthesizerangefromadoubl~dedcoldlegguillotine(DECLG)pipeseverancedowntoasix-inchequivalentdiameterholeinthereactorcoolantsystem'.ThisrangewaschosenbecauseitisconsistentwiththesizerangeforlargeLOCAsanalyzedinReference1.3.1.1.12MediumLOCAThemediumLOCArangeofbreaksrepresentsallreactorcoolantsystemrupturesinsidecontainmentofequivalentdiameterfrom2inchesto6inches.Theflowareaofapressurizersafetyvalveis3.644squareinches,therefore,failureofoneorallpressurizersafetyvalveswouldfallwithinthiscategoryofLOCA.TheflowareaofapressurizerPORVis2.0squareinches.FailureoftwoormorepressurizerPORVswouldbeincludedwithinthiscategory,however,therandomfailureoftwocomponentsisnotconsideredcredibleand,therefore,willnotbeconsideredfurther.ThisrangewaschosenbecauseitisbelowthelowerboundofthelargeLOCAanalysisinReference1andabovethesizeholewhereaccumulatorinjectionwouldoccur.ThissizerangeincludesthemostlimitingsizebreakofthesmallbreakLOCAanalysisinReference1,a3-inchcoldlegbreak.3.1.L19SmallLOCAThiscategoryofeventscomprisesbreaksinsidecontainmentintherangeof2-inchto3/S-inchequivalentdiameterholes.AlsoincludedareRCPsealfailures,controlrodejectionsandsinglefailuresofPORVs.Theupperboundofthiseventwaschosenbecause,forholeslessthan2inchesindiameter,noaccumulatorflowisrequiredtokeepthecorecovered.Thelowerboundisthesizeholeforwhichnormalchargingflowcanmaintainliquidinventory.Forbreaksinthissizerange,heatremovalbythesecondarysystemsinadditiontotheheatremovalbytheECCSsystemswouldberequiredtopreventcoredamage.3.1.1.1.4SteamGeneratorTubeRuptureAlthoughthiscategorycanbeindudedinthesmallLOCAcategory,itisseparatedduetoitsuniqueeffectsontheplantandtheenvironment.Asteamgeneratortuberupturemayresultindirectbypassofthecontainmentboundary,ifsteamgeneratorsafetyorreliefvalvesliftorthesteamgeneratorisnotisolated.Thiscategoryincludesallabnormalleakages,includingmultipletuberupturesfromthereactorcoolantsystem(RCS)intoonesteamgeneratorinexcessofchargingpumpmakeupcapacityandwhichwouldbeexpectedtoresultinactuationoftheECCS.3-1 3.1.1.1.5BreaksBeyondECCSCapabBityTwodassesofLOCAsthatmaybebeyondthecapacityofECCShavebeenidentified:simultaneousruptureoftwoormorelargepipesandacatastrophicreactorvesselrupture.3.1.1.1.6InterfacingSystemsLOCAThiscategoryconsidersRCSsupportingsystemsthathavedirectpipingconnectionsbetweentheRCSandsystemsoutsidethecontainment.Pipingand/orvalvefailuresassociatedwiththesesystemshavethepotentialtocauseaLOCAthatcoulddisabletheECCSfunctionsandbypassthecontainment.Thelimitingfactorsinthistypeofeventarepossiblelossofprimarycoolantoutsideviaadirectreleasepathtotheenvironment.3.1.12TransientsTentransientinitiatingeventcategorieswereanalyzed.Theyweregroupedintocategoriesbasedonplantresponse,signalactuation,systemsrequiredformitigationandsubsequentplant-relatedeffects.Thefollowingsectionsprovideageneraldescriptionforeachtransientinitiatingeventcategory.3.1.1.2.1TransientsWithtbeSteamConversionSystemAvailableThiscategoryincludeseventsandsupportsystemlossesnotevaluatedseparatelywhichcauseareactortripandwouldoccurwiththesteamconversionsystemavailabletoremovedecayheat.Practically,thismeanseventsinwhichmainfeedwaterisabletosupplythesteamgenerators.3.1.1.22TransientsWithouttbeSteamConversionSystemAvailableThiscategoryindudeseventsandanysupportsystemfailuresnotevaluatedseparatelyasspecialinitiatorsthatwouldoccurwiththesteamconversionsystemnotavailabletoremovedecayheat.Practically,thismeansthatmainfeedwaterisnotavailabletosupplythesteamgenerators.0'.1.L26LargeSteamLine/FeedlineBreakThiseventincludesmainfeedwaterbreaksandmainsteamlinebreaksbothinsideandoutsidecontainmentandanyspuriousvalveopeningsthatcouldresultinalargereactorpowerincreaseduetoasecondarysidesteamdemandincrease.ThiseventincludesthoseunanticipatedtransientsthatrequirerapidsecondarysideisolationandECCSactuation.Theplantresponseismodelledasifthebreakoccursinsidecontainmentbecauseabreakinsidecontainmentpresentsthegreatestchallengetosafetysystems.3.1.12.4LossofOffsitePowerThiseventresultsfromacompletelossoftheoffsitegridpoweraccompaniedbyaturbinetrip.FollowingtheinitiallossofACpower,atleastonedieselgeneratorwould,bydefinition,comeonlinetosupplyelectricalpower.Eventswherebothdieselgeneratorsfailareincludedunderthestationblackoutevent.3.1.12.5StationBlackoutThiseventresultsfromthelossofoffsitepoweraccompaniedbythelossoftheonsiteemergencyACpowerdistributionsystem.3.1.1.2.6AnticipatedTransientWithoutScramThiseventinvolvesthefailureoftheRPSsystemtotripthereactorfollowingananticipatedtransient.Theeventcouldbeinitiatedbyanyeventwhichrequiresareactortriptomitigatetheevent.Thiseventisbasicallyatransientdescribedineithersection3.1.1.2.1or3.1.1.2.2abovecombinedwiththefailureprobabilityoftheRPSsystem.0;3-2 3.1.12.7LossofEssentialServiceWater,ThiseventinvolvesthecompletelossofESWcoolingtooneunit'scomponentsforanyreasonotherthansupportsystemfailures.AtotallossofESWwouldcauserisingtemperaturesintheCCWsystem.WiththelossofCCWcooling,RCPsealtemperaturesandbearingtemperatureswouldincreaseandtheoperatorswouldbeexpectedtoinitiateareactortrip.Followingthereactortrip,componentsrequiringESWcooling,includingtheCCWsystem,wouldnotbeavailableforaccidentmitigationuntilESWcoolingisrecovered.Inaddition,aconsequentialRCPsealLOCAmustbeassumedbecausecoolingtothesealswouldbelost.3.1.1.2.8LossofComponentCoolingWaterThiseventinvolvesthecompletelossofCCWcoolingtooneunitforanyreasonotherthansupportsystemfailures.ThiseventisanalyzedseparatelyfromthelossofESWeventbecause,forthisevent,thecontainmentspraysystemwouldbeavailabletopreventcontainmentfailureifcoredamageoccurs.AsinthelossofESWevent,theoperatorswouldbeexpectedtoinitiateareactortriponhighRCPbearingandsealtemperatures.3.1.1.2.9Lossof250VDCLossofasingletrainof250VDCwouldcausealossofpowertotheRCPundervoltageandunderfrequencysensingrelayscausingthereactorprotectionsystemtosensealowflowcondition.Concurrentlossoftwotrainsof250VDCisnotevaluatedbecausetheinitiatingeventfrequencyisverysmall.Followingtheresultingreactortrip,thetrainwhichlostDCpowerwillnothavecontrolpoweravailabletothesafetyandnonsafetyequipment.Lackofcontrolpowerwillpreventtheautomaticstartingofstandbyequipmentnecessarytomitigatetheevent.3.1.1.2.10InternalFloodingTheonlyinternalfloodingscenarioofsignificanceinvolvedanESWdischargelinebreakthatresultedinfloodoftheturbinebuildingsub-basement.TheNESWpumpsarehousedinthesub-basementandarepostulatedtofailduetothesubmergenceofthemotors.Thesepumpsprovidecoolingwaterforthecontrolaircompressorsandplantaircompressorswhichinturnarepostulatedtofail.Failureofthecompressorswillresultinclosureofthefeedwaterregulatingvalveswhichsubsequentlycauseareactortrip.ThiseventwasjudgedtobeboundedbythetransientwithoutthesteamconversionsystemavailableeventtreediscussedinSection3.1.1.2.2.3-3 TABLE3.1-1SUMMARYOFINTERNALINITIATINGEVENTFREQUENCIES~CtegoOzitiLargeLOCAMediumLOCASmallLOCASteamGeneratorTubeRuptureBreaksBeyondECCSCapabilityInterfacingSystemsLOCA(V-Sequence)TransientsWiththeSteamConversionSystemAvailableTransientsWithouttheSteamConversionSystemAvailableFrequencyperC3.00E449.17E446.8E-037.2E-033.0E476.7E-073.81.2E41Variance(perYearSuar5.5E473.9E466.3E-052.9E-055.5E-132.5E-138.90.28101213141516LargeSteamline/FeedlineBreakLossofOffsitePowerStationBlackoutATWSLossofEssentialServiceWater3.3E444.0E421AOE454.67E453.73E45Lossof250VDCInternalFlooding1.16E-023.00E43LossofComponentCoolingWater8.71E445.5E479.0E441.11E-101.22E496.04E-101.14E464.42E455.04E46 3.12Emnt-LineEventTreesEventtreesweredevelopedforeachoftheinitiatingeventsdescribedaboveandareshowninFigures3.1-1-3.1-16.Theeventtreeanalysisforeachinitiatingeventwasdevelopedtopresentthemostimportanteventsandsystemsnecessarytomitigatetheevent.Theseeventsandsystemsmodelledwithintheeventtreesarereferredtoastopeventsandmaybegenerallydividedintotwocategories.Thefirstcategoryincludessystemsneededtoprovideadequatecorecoolingtopreventseverecoredamage.Thesecondcategoryincludessystemsusedtomitigateimpactoncontainmentintegrityfollowingseverecoredamage.Sometopeventsfiteachcategorydependingontheaccidentsequence.Supportsystemsrequiredforthesuccessofthetopeventswerenotmodelledwithintheeventtree.Supportsystemswere,however,modelledwithinthefaulttreesandfactoredintotheaccidentsequencesthroughthefaulttreelinkingprocessoftheaccidentsequencequantification.Theaccidentprogressionwasanalyzedwiththepurposeofpreventingseverecoredamageormitigatingthe,containmenttransientfora24hourperiod.The24hourperiodwasbasedontheassumptionthatextraordinaryandgenerallyunquantifiableoperatoractionscanbetakenby24hourstomitigatetheconsequencesofmostaccidents.ThisassumptionwasconsistentwithpastPRAsandwasspecifiedinReference20.FortheECCSandcontainmentspraysystems,operationwasmodelledintwophases:theinjectionphaseandtherecirculationphase.Althoughthelengthofeachphasevarieddependingonthenumberofpumpsrunningineachphase,thetotaltimemodelledforanyaccidentscenariowas24hours.Inordertosimplifythemodellingwithinthefaulttreesforthesesystems,theinjectionphasewasmodelledforone-halfhourandtherecirculationphasefor24hours.Usingthesemissiontimeswasconservativeinthatatotalof24.5hoursofruntimewasmodelledwhenonly24hourswasrequired.Inaddition,allimportantoperatoractionsneededtotransitionfrominjectiontorecirculationwereincludedaswellasapumpstartforthebeginningofeachphase.BecausethisprojectintegratedtheLevelIandLevelIIanalyses,thesuccesscriteriafortopeventsconsideredtheeffectofthesystemsonthecontainment.Indevelopingtheeventtreesuccesscriteria,preventionofcoredamagewasassumedtobepossibleonlyifcontainmentoverpressurizationwasprevented.Ifthecontainmentpressureincreasedabovetheultimatecapacity,thengrosscontainmentfailurewasassumedandallinventoryavailableforECCSrecirculationwasassumedtobelost.Itshouldbenoted,therefore,thatwhenanaccidentsequencewasindicatedassuccessful,neitherseverecoredamagenorgrosscontainmentfailurewouldhaveoccurred.Becausemodellingcontainmentisolationwithinthesystemeventtreeswouldhaveincreasedthecomplexityoftheeventtrees,failuretoisolatethelinespenetratingcontainmentwasmodelledwithintheLevelIIcontainmenteventtree.Foraccidentsequenceswhereseverecoredamageoccurred,containmentprotectionsystemsweremodelledastopeventstoshowtheeffectofsupportsysteminteractionsonthesystems.Inaddition,thismodellingprovidedaquantifiedassessmentofthestateofthecontainmentprotectionsystemsforuseintheLevelIIPRA.Thesuccessorfailureofatopeventfollowingcoredamage,however,didnotimplythatthecontainmenteitherremainedintactorfailed.ThespecificcontainmentresponsetothesuccessorfailureofcontainmentsystemswasmodelledasappropriateintheLevelHanalysis.Forallinternalinitiatingeventtreeaccidentsequences,theicecondenserwasassumedtofunctionasdesignedtomitigatetheeffectofRCSorsteamgeneratorblowdownoncontainment.Asaresult,theicecondenserwasnotmodelledasatopeventforinternalinitiatingevents.Theicecondenserisacompletelypassivesystemwithnosupportsysteminterrelationshipswithothersystems.Ananalysisoftheprobabilityoficecondenserfailurefollowinganinternalinitiatingeventwasperformed.Thisanalysisconcludedthat,iftheicecondenserwasdemandedfollowinganinternalinitiatingevent,thefrequencyofoccurrenceofsuchasequencewouldbesufficientlylowthatthecoredamagefrequencyforthesequencewouldbebelowthecutofffrequencyspecifiedinReference20asrequiringfurtherevaluation.3-5 Successcriteriafortopeventsweretakenfrommanysources.Wherepossible,theequipmentrequirementsfromtheanalysesinReferenceIwereused.Becauseoftheirinherentconservatism,analysesinReferenceIwereconsideredtopresentthegreatestchallengetoplantsystems.IfananalysiswasnotavailableinReferenceItosupportdevelopmentofsuccesscriteria,thenequipmentsuccesscriteriawereselectedbasedontheemergencyoperatingproceduresortheirbackgrounddocumentsandthesuccesscriteriawasverifiedusingtheMAAPcomputercode(Reference13).Insomecases,successcriteriaweredefinedintheeventtreetodeterminethesubsequentaccidentprogression.Thesuccessofthesetopevents,however,didnotcauseorpreventcoredamage.ThebasisforsuccesscriteriadeterminationisdefinedandreferencedinTables3.1-2-3.1-17.~iTheinitial.conditionoftheNSSSwasusuallyassumedtobenormaloperatingtemperature,pressureandpressurizerlevelwiththereactorat100%power.Therewereexceptionstotheseconditionswhentheinitialconditionswouldimposemorelimitingsuccesscriteriaonthetopevents.Forexample,thesuccesscriteriaforthesteamlineruptureeventtreeweretakenfromtheReference1.Theinitialoperatingconditionofthereactorassumedforthisanalysiswashotzeropowerwiththereactorcriticalinthesourcerange.Inallcases,however,thesuccesscriteriaweretakentobethemostlimitinginordertoboundallinitialModeIor2operatingconditionsofthereactor.Consequentialfailures,whichwouldtransformtheaccidentsequencefromoneinitiatingeventcategorytoanother,werenotexplicitlymodelledwithintheeventtrees.Rather,consequentialfailureswereboundedbytheinitiatingeventcategorizationandfrequencydevelopment.Forexample,atransienteventcouldleadtocoredamagebecauseofalossofessentialservicewaterwhich,inturn,wouldcauseaconsequentialRCPsealLOCA.RatherthanmodeltheeffectsofaconsequentialRCPsealLOCAwithinthetransienttree,aseparateinitiatingeventandaccidentsequenceanalysiswasperformedto,quantifytheeffectsofalossofessentialservicewater.Allconsequentialfailurescausedbythelossofessentialservicewaterwereconsideredboundedbythelossofessentialservicewatereventtree.

LLOACCLPICSILPRCSRCFISUCCESS2ALCAtClf'aLR6ALRI7AlRlf'ALC9ALCIIOALClfIIALl2aL!l3at.lf'4al.R!5aLRIl6aLRIFI7ALCl8ALCIl9ALCIF20ALV2lALvl22ALvlf'3ALR24AI.RI25ALRIF26At.C27ALCI28ALCIf'9ALV30ALVI3lALvlf'VENTLLOACCLPICSII.PRCSRHlCFEVENTNAHELARGEI.OCAINII'IATINGEVENTACCUHUL*TI3RSRHR(LOVPRESSURE>INJECTIONCONTAINMENTSPRAYINJECTIONRHRCLOVPRESSURE)RECIRCULATIONCONTAINMENTSPRAYRECIRCULATIONHYDROGENIGNITORSCONTAINMENTRECIRCULATIONFANSCATEGORYSUCCESSALCaLCtALClf'l.RALRIAI.Rlf'l.ALIALIFALVALVIALviFDESCRIPTIONNOCOREDAMAGE,NOCONTAINMENTfAILURELARGELOCA,LOvPRESSURE,CSRFalLsLARGELOCALOVPRESSURE.CSRf.Hlf'AILLARGELOCALQVPRESSURE,CSRHI.Cf'AILLARGELOCA,LOVPRES,CTHEATREHOVALLGLOCACTHEATREMOVALSUCCESSHlFAILSLGLOCA,HLCFFAIL.CTHEATREMQvEDLARGELOCALOvPRESSURELARGELOCA.LQVPRESSURE,Hlf'AILSLaRGELOCA.LovPRESSURE.'lc,CFFalLLARGELOCA.LOVPRESSURE.CTDRYLaRGELOCa.LOv~RESSO'PYMtf'alLSLGLOCA.LOVPRES,CTDR1,Htf.CFrAILFigure3.1-1"LargeLOCAEventTree3-7 SKgPER7~UKECARQg,)sog~bleODgpp~rgCGF~CnCnCn<<e<<sooCCL'LOOUOgXXXX'XZDNcnco4otoCococo<<CUCnrtllcaCmcncncncocn00attncoooXXXXZCo4oCnCoCortllerm0<<CUCnr0UIhm50<<CUCnrIIIcahmCh0<<CUCnrIIIUIh.m0CUalCUCUalCUalCUCUCnCnCnCnCOCnCnCnCnCnrrrrtrrrrrNcn4I4.IL.W4.4.<<4-4.IL4.Io<<UcccuUuo<<Icccuou350cccuoub>3XXDJJJJJJDJJJXXXXZXXXfXZXXXXXZNNNNcncocoCocncoNNNcoCoCoNcoNNcoNcococoNcn4ncocncoChCOWCCNJŽgJJC+o)%~<<eJZ-WJ~w>X=Nwcn>JIcntCNO<<J+CJOZXONZ4~o<<U<<ZQJ<<OCXIIWW4<I-<WWWONCOWcnC~CŽ~UCOCO~<<UAZNuJzc+Uc+wvgz4Llwwwwcuczcn>l-NcndNPOPncn>l-cn++cn++NcoONOUNNCnNOUNCONNNCnl-VwzwwowwwwzwcocnwNcowwUocwdccNcctLcw+IL2LC-QLCnLLLa.C<<a.CCa.CCQLNLaQa~iLzxczxxbi4333333zcu-5I.<<HL-HHO4IIDOODDD>>czzuzzxxIZJXUJJJJJJXXXZO<<CZIJCQ<<Q+ggl-M4QQdQ~4<<OAUUZUUZUUUUUxoooouoooxDOoOOOOODDODDOOQWJ<4JJCJJJJA'JJJJJJuuoOUJDOJJoJJJJDOJJJJJJJJoOUJJJJJJI'awa~~cc~~WOZ'ZZZZZZXZZZZZZZXXZNZZAZNNNNCncnNcncnNNNNNcnNNNNNNCLNONow444.4.I4IOI-Uecccouo>>cccooo333QZZZZZXXXZJJJJJJJJJZZXucoNcoNNcocoN4ocoNcnCnNcocoNcococoN4nazoDlAU4lZII-CZCZWD<<otn?NCOUlD4ICCI-<<AC<<JC2IZazooJ4IUgOWUD)W>>>CCO2zbouooC<<LJWWWV2aAZJCWJWeZ>>A~cINNZ&OD~CNDDCUNCWVzwa.~NCZINWWCOC>naI-DCI-ZOI-Czooxo~~zNLzo<<<<zCo+gACWCnWtdZJ<HJ>ZWDZZZJXONzcozwzIZ+~ON~LJ<<U<<ZgxUWgvCDCAUUNc'22<<OCnII>4luouwoZo>Dwx<wcggzcox~o8gaaDualca<<<<CCC2Joa.CJNQLCO<<4.ZCZODVZJUUW920aosoS3S-CoQ,lyit4IiJlt,)'a>>nICJ SLOHP2Oa6PBFCstHPRCsRHlCfISUCCESSSHR3SHRI4SHRIF5SHC6SHCI7SHCIF8SUCCESSSH10SHI11SHIP12SUCCESS13SHR14SHRI15SHRIF16SHC17SHCItgSpl'lc'9SUCCESS20S'H21SHI22SHIP23SHR24SHRI25SHRII'6SHC27SHCI28SHCIF29SH30SHI31SHIF32SHR33SHRI34SHRIF35SHC36SHCI37SHCIF38SHV39SHVI40SHVIFEVEN'ISLOHP2OA6PBFCSIHPRCSRHlCfEVENTNAHESMALLLOCAINITIATINGEVENTECCSCHIGHPRESSURE>INJECTIONRCSCOOLDOVNUSINGAFVANDSTEAHDUMPPRIHARYBLEEDANDFEEDCQNTAINHENTSPRAYINJECTIONHIGHPRESSURECOLDLEGRECIRCULATIONCONTAINHENTSPRAYRECIRCULATIONHYDROGENIGNITERSCONTAINMENTRECIRCULATIONFANSCATEGORYSUCCESSSHRSHRISHRIFSHCSHCISHCIFSHSHISrilfSHVSHVISHVIFDESCRIPTIONNOCOREDAMAGE,NOCONTAINMENTFalLURESHAlLLOCA.HIGHPRESS.CTHEATREHOVALSHLOCACTHEaTREMOVALSUCCESSHlFAlt.SSHLOCA,Hl,CFFAILCTHEATREMOVEDSHALLLOCA.HIGHPRESSURE.CSRFAILSSkaLLLOCA.HIGHPRESSURE.CSRLHlfatLSHLOCA.HIGHPRESSURE.CSR.HLCffalLSkaLLI.OCA,HIGHPRESSURESMALLLOCA,HIGH~PRESSURE.HlFAILSSHALL.I.QCA,HIGHPRESSURE.Hl4Cf~*h.SHALLLOCA.HIGHPRESSURE.O'TDRYSHALLLOCAHIGHPRESS.CTDRY,HlFAILSSHI.QCA.HIGHPRES,CTDRY.HlLCfFAILFlgLEC3ai3SmallLOCAEventTree3-9 Pa'-saiihh/isagsCCshhj"siiiaiksaaisssii".-s05aii";ihaaa".asiassssk-".aAs=".aisiissis-".i4;"jgggg."assai-.'asi."";aa'*.ll<<IIclrh'0hsa0oIvclrhgpohoNslcarhoh0A0Nslcarh0aao0DraIIarho50toslclrh0IalhorslhrhoIacosaoIvorh04000sIIarhotoh0slclrhot0h~rvsaavslIvalaial1Islslclclclclcacaclcacaairrrrrrrrrrhhhhslhhhhh'0o0oo00oo05passhaablatIogasoassisl0aa5hsatoho505<IIC~lslVIaKIJaIIILLC7$Cma.<<-ad%Q)y~QQQQQola0laLLLgqIslajalguskagaalKIJIdIL'LHZHgallDHQlgg.=-o"-."--"8M'-"a)ICSICI~)SrnLrICCCLl980'5050333~~~

.Ir~rn~402.ENVpNp-M1I ISLBRHGIBRvcILEaK2V3V4V5V6V-7VEVENTISLBRHHP2GIBAF4RCERVCEVENTNAKEINTERFACINGSYSTEHSLOCaRHRSYSTEHBREACHECCSCHIONPRESSURE>INJECTIONOPERATORACTIONTOISIS.ATERHRSEALLOCAAUXILIARYFEEDVATERACTUATIONRCSCOIB.DOVNaNDRvSTCONSERVATIONRHRRELIEFVALVECLOSURECATEGORYDESCRIPTIONLEAKNOCOREDAHAGE.PRIHARYCOILANTRELEaSEDVCOREDANAGE.INTERFACINGSYSTEHLOCAFigure3.1-5InterfacingSystemsLOCAEventTree3-11 vEfCSI'SRHlCF'CR2aLRI3ALRIFa>C5aLCI6ALCIf7ALVaAlvl9AI.VIF'VENTVEF'SICSRHICF'VENTNaMEBREaKBEYONDECCSCAPaBILITYINITIATINGCONTAINMENTSPRAYINJECTIONCONTAINMENTSPRAYRECIRCULATIONHYDROGENIGNITERSCONTAINHENTRECIRCULATIONF'ANSCA'tEGORYal.RALRIAl.RlfALCALCIALCIF'lVALVIALVlfDESCRIPTIONLaRGELocA,LovPREs.cTHEATREHOVALLGLOCACTHEATREHOVALSUCCESSHlfAILSLGLOCA,HLCFF'AIL,CTHEATREHOVEDLARGELOCA,LOVPRESSURE,CSRF'AILSLARGELOCA.LOVPRESSURE.CSRLHlfAII.LARGELOCA,LOVPRESSURE,CSRPI.CffafLLARGELOCA,LOVPRESSURE,CTDRYLARGELOCA.LOVPRESS.CTDRY,HlfAILSLGLOCA,LOVPRES,CtDRY.Hl1CffAILFigure3.14BreaksBeyondECCSCapabilityEventTree3-l2 TRAAftOA5HFIPBfCSIHPRCSRHICfISUCCESS2SUCCESS3SUCCESS4SUCCESS5THR6THRI7THRIF8THC9THCI10TMC!f11SUCCESS12TH13THI14THIF15THR16THRI17THRIFISTHC19THCI20THCIF21THV22'THVI23THVIFEVENTTRAAFIOA5HF1PBFCSIHPRCSRHlCF'VENTNAHETRANSKNTSV/STEAHCONV.SYSTEMSAVAIL.AuxILIARYFEEDuaTERaCTUATIDNOATODEPRESSURIZE*STEa~GENERaiORHAINFEEDVATERPRIMARYBLEEDANDFEEDCONTAINMENTSPRAYINJECTIONHIGHPRESSURECOt.DLEGRECIRCULAI'IONCONTAINMENTSPRAYRECIRCULATIONHYDROGENIGNITORSCONTAINHENTRECIRCULATIONFANSCATEGORYSUCCESSTHRTHRITHRIFTHCTHCITHCIFTHTHITHIFTHVTHVITHVIFDESCRIPTIONNOCOREDAHAGE,NOCONTAINMENTFAILURETRANSIENT,HIGHPRESS,CiHEATREMOVALTRANS,CTHEATREMOVALSUCCESS,HIFAILSTRANS,HlLCfFAIL.CTHEATREHOVEDTRANSIENT,HIGHPRESSURE.CSRFAILSTRANSIENT.HIGHPRESSURE.CSRIHlfAILTRANS,HIGHPRESSURE,CSR.Hl,CfFAILTRANSKNT,HIGHPRESSURETRANSIENT,HIGHPRESSURE.HIFAILSTRANSIENT.HIGHPRESSURE.HlLCfFAILTRaNsKNT,HIGHPRESSURE.CTDRYTRANSIENI'.HIGHPRESS.CTDRY.HIFAILSTRANS,HIGHPRES,CTDRY.HlLCfFAILFigure3.1-7TransientsWithSteamConversionSystemsAvailableEventTree3-13 TRSAflPBFCSIHPRCSRHlCfISUCCESS2SUCCESS3TMRTMRI5THRIF6THC7THCI8'IMCIF9SUCCESS10THIlTHI12THIF13THR14THRI15THRIF16THC17THCI18THCIF19THV20THVITHVIFEVENTTRSAFIPBFCSIHPRCSRHlCiEVENTNAHETRANSKNTSV/0STEAHCONVERSIONSYSTEHSAUXILIARYFEEDVATERACTUATIONPRIMARYBt.EEDANDFEEDCONTAINMENTSPRAYINJECTIONHIGHPRESSURECOLDLEGRECIRCULATIONCONTAINMENI'PRAYRECIRCULATIONHYDROGENIGNITERSCONTAINMENTRECIRCULATIONfANSCATEGORYSUCCESSTHRTHRITHRIFTHCTHCITHCIFTHTHITHIFTHVTHVITHVIFDESCRIPTIONNOCOREDAMAGE,NOCONTAINMENTFAILURETRANSIENT,HIGHPRESS,CTHEATREHOVALTRANS,CTHEATREMOVALSUCCESS.HlfAILSTRANS.HIbCFFAILCTHEATREHOVEDTRANSIENT,HIGHPRESSURE,CSRfAILSTRANSKNT,HIGHPRESSURE.CSRbHlFAILTRANS.HIGHPRESSURE.CSR,Hl,CFfAII.TRANSIENT,HIGHPRESSURETRANSIENT.HIGHPRESSURE.HlFAILSTRANSIENT.HIGHPRESSURE.HIbCfFAILTRANSIENT,HIGHPRESSURE.CTDRYTRANSIENT,HIGHPRESS.CTDRY,HIFAILSTRANS,HIGHPRES.CTDRY,HIbCfFAIL.Figure3.14TransientsWithoutSteamConversionSystemsAvailableEventTree3-14 SLBHP3HSIAfSPBF'SIHfRCSRHlCfISUCCESS2SUCCESS3THR4THRI5THRIf6tHC7THCI8THCIF'SUCCESS10THI1THITHIf13TMR14TMRI15TMRIf16TMC17tMCIi8TMC,F19THv20THvl21THVIF'2THR23THRI24THRIF'5THC.26THCI27THCIf28THVP9THVI30THVIF'1THR32THRI33THRIF'4THC35THCI36THCIF'7THV38THVI39THVIF'VENTSLBHP3HS1AF'PBfCSIHPRCSRHlCfEVENTNAHESTEAHLINEBREAKINITIATINGEVENI'CCS<CHARGINGPUMP1INJECTION/BORATIONSECONDARYSIDEISOLATIONAUXILIARYfEEDvatERacTuaTI0Nv/sLBpRIHaRYBLEEDaNDfEEDCONTAINMENTSPRAYINJECTIONHIGHPRESSURECOLDLEGRECIRCULATIONCONTAINMENTSPRAYRECIRCULATIONHYDROGENIGNITERSCONTAINMENTRECIRCULATIONfANSCATEGCRYSUCCES"THRTHRITHRIF'HCTHCITHClfTHTHITH'IfTHVtHVITHVIFDESCRIPTIONNOCOREDAMAGE.NOCONtalNMENtF'alLURETRANSKNT,HIGHPRESS.CTHEATREMOVALTRANS,CtHEATREMOVALSUCCESS,HIfAILSTRaNS.Hl6CffatL.CTHEATREMOVEDTRaNSIE~T,HIGHPRESSURE.CSRfalLS'TRANSIENT,HIGHPRESSURE.CSR6HlfAILTRANS,HIGHPRESSURE.CSR,HLCFAILTRANSIENT,HIGHPRESSURETRANSIENT,HIGHPRESSURE.HlfAILSTRaNSIENt.HIGHPRESSURE.Hl6CffalLTRANSIENT.HIGHPRESSURE.CTDRYTRANSIENT.MIGMPRfSS.CTDRr.MlrAILSTRANS.HIGHPRES,CtDRY,Hl6CF'AILFigure3.1-9LargeSteamLine/FeedlineBreakEventTree3-15 LSPAF'IPBF'SIHPRCSRHICF'SUCCESS2SUCCESSTHRTHQI5THRIf6THC7THCI8THCIF'SUCCESSIOT<THIl2THlfI3THRI4tHRIl5THRIfTHCITTHCIl8THCIF'9THV29THVItHVlfEVENTLSPAF'IPBfCSIHPRCSRHICF'VENTNAHELOSSOF'fF'SITEPOVERAUXILI4RYfEEDVATERACTUATIONPRIHARYBI.EEDAHDSEEDCONT4INHENTSPRAYINJECTIONHIGHPRESSURECOLDLEGRECIRCULAtlONCONTAINHENtSPRAYRECIRCULATIONHYDROGENIGNITORSCONTAINHENTRECIRCULAT'IONF'ANSCATEGORYSUCCESSTHRTHRITHRlfTHCTHCITHClfTH'IHITHlfTHVTHVITHVlfDESCRIPtIONNOCORcDAHaGc.NOCONTalNHcNTfAILURcTRA~SIENt,HIGHPRESS.CTHEaTREHOvaLTRANS.CTHEATREHOVALSUCCESS,Hlfall.STRANS.HlLCffAILCTHEATREHOVEDTRANSIENT,HIGHPRESSURE.CSRF4ILSTRANSIENT,HIGHPRESSURE.CSRLHlf4ILTRANS.HIGHPRESSURE.CSR.Hl.CF'aILTRANSIENT.HIGHPRESSURETRANSIENT,HIGHPRESSURE.HlfalLSTRANSIENT,HIGHPRESSURE.HlICffaILTRANSIENT.HIGHPRESSURE.CTDRYTRANSIENT.HIGHPRESS.Cl'RY.Hl.fAILSIRANS.HIGHPRES,CtDRY.HlICF'AILFigure3.1-10LossofOffsitePowerEventTree3-l6

'a~I SE@PERILCAEQusoA~bte0~ApertureCardChgtIIp<<atnrnuttecclocunreutheaco<<acnrvloiesoatnrnulhectcoatnrnoh<<<<<<>><<<<ecucuecucucucucucu8nnnnnnnnnrrrrrrrrIcc~=--:5RE555hh.555.".PQk'=54t".H.35M5"."Q.*-B~"~"><z~~h~~~5~B~~agi"aa55a.g.a.888.5g(.Seaco<<atnrnulleoo<<cunre4wectlo<<cunrem)4Ieso<<atnrnoaeso<<cunrrnnctenennctaulututulullaututulorIcriIcIgceeeeeeeeeealgaluICI<<~c~,CgcCII)4CL>c+)4ecg+Q<<ect+CcLbOlVIZggaOZI-W~iiitP'gcaccgWCCOcIOCCcoeelOCCI-I-fiiiiiiV)COVICC~CnCCCCCSCC$QcrooCo5>>~ccVZOchwIZAIWWCW-IOC~)H>WXW+OutZa:zZZ<<Zal~aooRoI0J4%<<zeNCQia.ccztIIwccmIccxcccLJoozocil~C6M<<'0e.PlR8P.'aeC4'9.20505.0S3S-IgO~F>.CQtw~CM~~+iqlk0 Al'2AVCSICSRHlCfEVENTVDCAl'I'AVCSICSRHICfEVENTNANELOSSOfSINGLETRAINOf250VDCAUXILIARYfECDVATERACTUATIONlPERATORACTIONTOPROVIDEUNIT2APVCIDITAINHENTSPRATINJECTIONCONTAINHCHTSPRAYRECIRCULATIONHYDROGCNIGNITERSCON'IAINHCNTRECIRCULATIONI'ANSCATEGORYSUCCCSSTHRTHRI'THRIfTHCTHCIIHCIfTHVTHVITHVIfISUCCESS2SUCCESS~THRISTHRIf6THC7TICISTHCIfTHVIDIwvlIIIHVIfDESCRIP'IIONNOCOREDAHAGE.HOCONTAINHEHIrAILURETRANSICHT,HIGHPRESS.CTlC*TREHOVALTRANS,CTHEATREHOVALSUCCCSS.HlfAILSTRANSHlLClAILCTHEATREHOVEDTRANSIENT.HIGHPRESSURE,CSRfAILSTR*NSKNT.HIGHPRESSURE.CSRLHIfAIITRANS.HIGHPRESSURE,CSR,HLCffAILTRANSIENT,HIGHPRESSIRECTDRYTRANSICHT,HIGHPRESS.CTDRY.HlfAILSTRANS,HIGHPRELCTDRY.HlLClA!LFigure3.1-15LossofaSingleTrainof250VDCEventTree3-21 0~-~'

TRSPBFCSICSRHtCfISUCCESS?SUCCESS3THR4THRI5'HRIF6THC7THCI8THCIF9SUCCESS10TH11THI12THIF13THRIiTHRI15THRIF16THC17THCI18THCIF.19THV20THVI21THVIFEVENTTRSAFIPBFCSIHPRCSRHlCfEVENTNAHETRANSIENTSV/OSTEAHCONVERSIONSYSTEHSAUXII.IARYFEEDVATERACTUATIONPRIHARYBLEEDANDFEEDCONTAINHENTSPRAYQLIECTIQNHIGHPRESSURECOLDLEGRECIRCULATIONCONTAINNENTSPRaYRECIRCULATIONHYDROGENIGNITERSCONTAINHENTRECIRCULATIONfANSCATEGORYSUCCESSTHRTHRITHRIFTHCTHCITHCIFTHTHITHlfTHVTHVITHVIFDESCRIPTIONNOCOREDANAGE.NOCONTAINHENTFAILURETRANSKNT,HIGHPRESS.CTHEATREHOVALTRANS,CTHEATREHOVALSUCCESS.HlFAlLSTRANS,HltCfFAIICTHEATREHOVEDTRANSIENT,HIGHPRESSURE,CSRFAILSTRANSKNT.HIGHPRESSURE.CSRtHlfAILTRANS.HIGHPRESSURE.CSR,HLCFFAlLTRANSIENT,HIGHPRESSURETRANSKNT,HIGHPRESSURE.HlFAILSTRANSIENT.HIGHPRESSURE.HltCFFAlLTRANSKNT,HIGHPRESSURE.CTDRYTRANSKNT.HIGHPRESS.CTDRY,HlFAILSTRANS.HIGHPRES.CTDRY.HltCFFAILFigure3.1-16InternalFloOdinEventTree3-22 Q)0,0)

TABLE3.1-2LARGELOCASYSTEMSUCCESSCRITERIAEventTree~fgrnEquipmentSuccess~ri~lSystemOperatorDggn~dn~~A~iMission~Timhr~Rf~rgn~ggAccumulators(ACC)RHR(LowPressure)Iqjection(LPI)ContainmentSprayIqjection(CSI)3of3accumulatorsirjecttotheintactcoldlegs1of2RHRPumpsto1of3intactcoldlegs1of2TrainsNoneElectricPower,ComponentCoolingWater,SISignalElectricalPower,Hi-HiContainmentpressuresignalNoneNoneNone0.50.5RHR(LowPressure)Recirculation(LPR)1of2RHRtrainsswitchedfromtheRWSTtotherecirculationsumpandrestartedto1of3intactlegsElectricalPoweryComponentCoolingWaterManualvalve24changesinRHRsystem,pumpsrestarted4,333-23 TABLE3.1-2(Cont'd.)LARGELOCASYSI'EMSUCCESSCRITERIAEventTreeContainmentSprayRecirculation(CSR)HydrogenIgniters(Hi)EquipmentSuccess~ri~l1of2CStrainsswitchedfromtheRWSI'otherecirculationsump1of2trainsinbothupperandlowercontainmentSystem&QKB~nElectricalPowefpEssentialServiceWaterElectricalPowerOperatorQ~ingManualvalvechangesinCSsystemppumpsrestartedEnergizeIgnitersMissionT~imhr~Rf~~~241,4EngineeringJudgement,ContainmentRecirculationFans(CF)1of2trainsoperatingElectricalPoweryHi-HiContainmentPressureSignalpCCWNoneEngineeringJudgement TABLE3.1-3MEDIUMLOCASYSTEMSUCCESSCRITERIAEventTreeAccumulators(ACC)ECCS(HighPressure)Injection(HP2)RCSCooldownUsingAFWandSteamDump(OA6)EquipmentSuccess~ri~ril3of3accumulatorsinjecttotheintactcoldlegs1of2CCPsand1of2SIpumpsto1of3intactloops(SIcross-tieassumedshut)450gpmofAFWtoatLeast2of4SteamGeneratorsatLeast2of4S/GPORVSOpenedSystemD~~n~ni~NoneElectricPower,SlSignal,ComponentCoolingWaterElectricPower,ControlAir,MainSteamOperator~A~iNoneNoneInitiateCooldownwithin2Hoursfollowingaccident.initiationMissionT~imtheir~R330.5333-25 TABLE3.1-3(Cont'd.)MEDIUMLOCASYSTEMSUCCESSCRITERIAEventTree5mb'epressurizationandLowPhssureIqjection(OLI)EquipmentSuccess~ri~i~RCSdepressurizedbydumpingsteunfromatleast2of4S/GPORVs,andopening2of3pressurizerPORVs,1of2RHRPumpsinjectingto1of3intactcoldlegs,450gpmofAFWto2of4S/GsSystemD~~~~ElectricPower,ComponentCoolingWater,ControlAir,MainSteam,PressurizerPORVsOperator~AingDepressurizeRCSwithin20minutesofaccidentinitiation,verifyRHRinjectionMissionT~imhr~Rf~r~niR0.54,33ContainmentSprayhjection(CSI)1of2TfRlnsElectricalPowerRHi-HiContainmentpressuresignalNone0.5HighPressureColdLegRecirculation(HPR)1of2RHRtrainssupplying1of2Slandlof2CCpumps,to1of3intactlegsComponentCoolingWater,ElectricalPowerRRHRManualvalve24changesinSIsystemIsolateRWSTOpensumpvalvesRestartpumps4,33 TABLE3.1-3(Cont'd.)MEDIUMLOCASYSTEMSUCCESSCRITERIAEventTreeEquipmentSuccessgri,r~iSystemDgy~gnn;i~Operator~Ai~MissionT~hnhr~RRHR(LowPressure)Recirculation(LPR)1of2RHRtrainsswitchedfromtheRWSTtotherecirculationsumpandrestartedto1of3intactlegsEledricalPower,ComponentCoolingWaterManualvalvechangesinRHRsystem,pumpsrestarted244,33ContainmentSprayRecirculation.(CSR)1of2CStrainsswitchedfromtheRWSTtotherecirculationsumpElectricalPower,EssentialServiceWaterManualvalve?AchangesinCSsystem,pumpsrestartedHydrogenIgniters(Hi)1of2trainsinbothupperandlowercontainmentElectricalPowerEnergizeIgnitersEngineeringJudgementContainmentRecirculationFans(CP)1of2trainsoperatingElectricPower,NoneHi-HiContainmentPressureSignal,CCWEngineeringJudgement3-27 TABLE3.1QSMALLLOCASYSI'EMSUCCESSCRITERIAEventTree$+~ECCS(HighPressure)hjection(HP2)RCSCooldownUsingAFWandSteamDump(OA6)EquipmentSuccess~ri~ri1of2CCPsand1of2SIpumpsto1of3intactloops(SIcross-tieassumedshut)450gpmofAFWtoatLeast2of4SteamGeneratorsatLeast?of4S/GPORVSOpenedSystemDgy~l~~ElectricPower,SISignal,ComponentCoolingWaterElectricPower,ControlAir,MainSteamOperator~AcingNoneInitiateCooldownwithin2HoursfollowingaccidentinitiationMissionT~unhr~RFjn;n~0.5133PrimaryBleedandFeed(PBF)ContainmentSprayIrjection(CSI)Manuallyopen2of3PORVsandblockvalves,1of2SIand1of2CCpumps1of2TrainsElectricPower,CCWtoSIandCCpumps,ControlAir,PressurizerPORVsElectricalPowerK-HiContainmentpressuresignalOpen2of3PORVsandblockvalves.StartpumpsorverifypunlpsrunIllngNone0.50.54,33 TABLE3.14(Cont'd.)SMALLLOCASYSTEMSUCCESSCRITERIAEventTree5xstmHighPressureColdLegRecirculation(HPR)ContainmentSprayRecirculation(CSR)HydrogenIgniters(Hi)EquipmentSuccessgrinri~1of2RHRtrainssupplying1of2SIand1of2CCpumps,to1of3intactlegs1of2CStrainsswitchedfromtheRWSTtotherecirculationSMIlp1of2trainsinbothupperandlowercontainmentSystemDggn~n~i~ComponentCoolingWater,ElectricalPower,RHRElectricalPowerEssentialServiceWaterElectricalPowerOperator~AigrgManualvalvechangesinSIsystemIsolateRWSTOpensumpvalvesRestartpumpsManualvalvechangesinCSsystem,pumpsrestartedEnergizeIgnitersMissionT~imhr~Rfg~n~4,331,4EngineeringJudganentContainmentRecirculationFans(CF)1of2trainsoperatingElectricalPowersHi-HiContainmentPressureSignal,CCWNoneEngineeringJudgement3-29 TABLE3.1-5STEAMGENERATORTUBERUFfURESYSTEMSUCCESSCRITERIAEventTree5ufmAuxiliaryFeedwatertotheIntactS/G(A%2)EquipmentSuccess~rivari~1of3auxfeedpumpsto1intactS/GSystemD~~~i~ElectricPower,StartSignalOperator~Ai~~ProvideadditionalwatersupplyondepletionofCSTMissionT~imhr~Rigr~n~ih2445AuxiliaryFeedwatertotheFaultedS/G(AF3)1of2auxfeedpumpstothe:,faultedS/G..EledricPower,StartSignalProvideadditionalwatersupplyondepletionofCST45ECCS(HighPressure)Injection(HPI)S/GIsolationbyMSIVClosure(SGI)1of4SIorCCPsto1of4ColdLegsClosureofMSIVonfaultedS/GElectricPower,ComponentCoolingWater,StartSignalElectricPowerNoneClosureofMSIVonfaultedS/GN/A TABLE3.1-5(Cont'd.)SIAMGENERATORTUBERUPTURESYSTEMSUCCESSCRITERIAEventTree5m'ooldown&DepressurizationBeforeFaultedS/GFills(OA1)EquipmentSuccess~ri~riRCSpressureaboutfaultedS/Gpressurewithin30minusing2of4SGPORVs.Startcooldownwithin20min.SystemDylan+~~HPSI,AFW,MainSteam,ElectricPower,ControlAir,CCWOperator~A~iCooldownandDepressurize,TerminateSIMissionT~imh~r~Rf~~~241,4IntegrityMaintainedorRestoredinFaultedSteamGenerator(SSV)AllsecondaryreliefvalvesinfaultedS/GremainclosedNoneNoneN/AEngineeringJudgementCooldown&DepressurizationAfterFaultedS/GFills(OA2)RCSpressureaboutfaultedS/Gpressurewithin1hr.using2of4SGPORVs.Startcooldownwithin30min.,HPSI,AFW,ElectricPower,ControlAir,CCW,MainSteamCooldownand24DepressurizegTerminateSI1,43-31 TABLE3.1-5(Cont'd.)STEAMGENERATORTUBERUFI'URESYSTEMSUCCESSCRITERIAEventTreeCooldown&Depressurizationpcl'CA-3.1/3.2(OA3)EquipmentSuccess~ri~ritFaultedS/GandRCSreducedtoatmosphericpressureusing2of4S/GPORVsand1of3pressurizerPORVspriortodrainingtheRWSI'ystem~Dggig~ni~HPSI,AFW,ElectricPower,CCW,ControlAir,MainSteamOperator~AijrrgCooldown,Depressurize,ReduceSIMissionT~imhr~Rf~nhi241,4PrimaryBleedandFeed(PBBS)ContainmentSprayIqjection(CSI)Manuallyopen2of3PORVsandblockvalves,1of2SIand1of2CCpumps1of2TrainsElectricPower,CCWtoSIandCCpumps,ControlAir,PressurizerPORVsElectricalPowcrRHi-HiContainmentpressuresignalOpen2of3PORVsandblockvalves.StartpumpsorverifypunlpsrunningNone0.50.54,33 TABLE3.1-5(Cont'd.)STEAMGENERATORTUBERUPI'URESYSIXMSUCCESSCRITERIAEventTree$yggnHighPressureColdLegRecirculation(HPR)EquipmentSuccess~rigrani1of2RHRtrainssupplying1of2SIand1of2CCpumps,to1of3intactlegsSystem~~~i~ComponentCoolingWater,ElectricalPower,RHROperator+tinngManualvalvechangesinSIsystemIsolateRWSTOpensumpvalvesRestartpumpsMissionT~imhrR~~~n1,4,33ContainmentSprayRecirculation(CSR)HydrogenIgniters(Hi)1of2CStrainsswitchedfromtheRWSTtotherecirculationsump1of?trainsinbothupperandlowercontainmentElectricalPowerpEssentialServiceWater,ElectricalPowerManualvalvechangesinCSsystem,pumpsrestartedEnergizeIgnitersEngineeringJudgementContainmentRecirculationFans(CF)1of2trainsoperatingElectricalPower~Hi-HiContainmentPressureSignalCCWNoneEngineeringJudgement3-33 TABLE3.14INTERFACINGSYSTEMLOCASYSTEMSUCCESSCRITERIAEventTree5xsfmRHRSystemBreach(BRH)EquipmentSuccess~rir~iRHRpipingdoesnotfailSystemDmmdmkmNoneOperator~i~~NoneMission~Tim(h~r~Rfi~>~N/A34ECCSHighPressureInjection(HP2)OperatorActiontoIsolatethe.RHRSealLOCA(OIB)1of2CCPsand1of2SIPumpsto1of3IntactColdLegs.ClosureofRHRSuctionValvesIMO-310andIMO-320ElectricPower,SISignal,ComponentCoolingWaterElectricPowerNoneClosureofbothMOVs0.5N/A33AuxiliaryFeedwaterActuation(AF4)450gpmofAFWto2of4steamgeneratorsElectricPower,StartSignalProvideadditional24watersupplyonondepletionofCST33 TABLE3.14(Cont'd.)INTERFACINGSYSTEMLOCASYSTEMSUCCESSCRITERIAEventTreegyes~EquipmentSuccess~rir~iSystem~D~nd~ni~Operator~A~ingMission~Timhr~R~f~n~RCSCooldownandRWSTConservation(RCE)Cooldownanddepressurizeusing2of4SGPORVsand1of3PressurizerPORVsMainSteam,ElectricPower,ControlAir,PressurizerPORVsPerformcooldown24anddepressurizationtolessthan450psigpriortoRWSTdepletion,StopCTSpumps,TerminateSIRealignnormalcharging4,33ReliefValveClosure(RVC)RHRreliefvalveclosesNoneNoneN/AEngineeringJudgement3-35 TABLE3.1-7BREAKSBEYONDECCSCAPABILITYSYSTEMSUCCESSCRITERIAEventTreeContainmentSprayIqjection(CS9EquipmentSuccess~rigrani1of2TraInsSystemDgg~~i~ElectricalPower,I-HiContainmentpressuresignalOperator~A+~NoneMissionT~imhr0.5EngineeringJudgementContainmentSprayRecirculation(CSR)HydrogenIgniters(HQ1of2CStrainsswitchedfromtheRWSTtotherecirculationsunlp1of2trainsinbothupperandlowercontainmentElectricalPower,EssentialServiceWaterElectricalPowerManualvalve24changesinsystem,pumpsrestartedEnergizeIgnitersEngineeringJudgementEngineeringJudgementContainmentRecirculationFans(C$)1of?trainsoperatingElectricalPower,Hi-HiContainmentPressureSignal,CCWNoneEngineeringJudgement TABLE3.14TRANSIENTSWITHSTEAMCONVERSIONSYSTEMSAVAILABLESYSTEMSUCCESSCRITERIAEventTree/gentAuxiliaryFeedwaterActuation(AFI)EquipmentSuccess~ri~eri450gpmAFWfiowto2of4steamgeneratorsSystemDggn+~i~ElectricPower,StartSignalOperator~A~iProvideadditionalwatersupplyondepletionofCSTMissionT~imhr~Rf~~nggMainFeedwater(MFl)1outof2mainfeedwaterpumpsto2of4SGs-or450gpmAFWfromtheoppositeUnitto2of4SGsElectricPower,Condensate,MainSteam,AFWDefeatMFW24pumptripandMFWisolationsignalsStartpumps,Manualvalvechangestoalignsystems1,4OperatorActiontoDepressurizeSteamGenerators(OA5)Supplyatleast2steamgeneratorsfromatleastonecondensateboosterpumpwithin30minutesElectricPower,Condensate,MainSteam,ControlAir,MainSteamDepressurizeSGstoallowcondensateflow0.51,43-37 TABLE3.14(Cont'd.)TRANSIENTSWITHSTEAMCONVERSIONSYSTEMSAVAILABLESYSTEMSUCCESSCRITERIAEventTree&sf'rimaryBleedandFeed(PBP)ContainmentSprayIajection(CSI)EquipmentSuccess~ri~lManuallyopen2of3PORVsandblockvalves,1of2SIand1of2CCpumps1of2TrainsSystemDgg~~iElectricPower,CCWtoSIandCCpumps,ControlAir,PressurizerPORVsElectricalPowersHi-HiContainmentpressuresignalOperator~A+i~Open2of3PORVsandblockvalves.StartpumpsorverifypunlpsllnlnlngNoneMissionT~imhrR~f~~RR0.54,330.5~HighPressureColdLegRecirculation(HPR)1of2RHRtrainssupplying1of2SIand1of2CCpumps,to1of3intactlegsComponentCoolingWater,ElectricalPowersRHRManualvalve24changesinSIsystemIsolateRWSTOpensumpvalvesRestartpumps4,33ContainmentSprayRecirculation(CSR)1of2CStrainsswitchedfromtheRWSTtotherecirculationsulnpEledricalPower~EssentialServiceWaterManualvalve24changesinCSsystenlypunlpsrestartedR'onservativelyassumedonlythreecoldlegsavailabletominimizethenumberoffaulttreestobedeveloped,ThissuccesscriteriaisconsistentwiththeLOCAsuccesscriteria.

TABLE3.14(Cont'd.)TRANSIENTSWITHSTEAMCONVERSIONSYSTEMSAVAILABLESYSTEMSUCCESSCRITERIAEventTreeEquipmentSuccess~iii~riISystemDgg~nl~gi~Operator~AtirgMission~Timhr~Rrgnn@HydrogenIgniters(Hi)1of2trainsinbothupperandlowercontainmentElectricalPowerEnergizeIgnitersEngineeringJudgementContainmentRecirculationFans(CF)1of2trainsoperatingElectricalPowerpHi-HiContainmentPressureSignal,CCWNoneEngineeringJudgement3-39 TABLE3.1-9TRANSIENTSWITHOUTSTEAMCONVERSIONSYSTEMSAVAILABLESYSTEMSUCCESSCRITERIAEventTree5m'uxiliaryFeedwaterActuation(AFI)EquipmentSuccessgrii~l450gpm,AFWfiowto2of4steamgeneratorsSystemDgg~~ii~ElectricPower,StartSignalOperator~A~iProvideadditionalwatersupplyondepletionofCSTMission~Tim(h~r~Ref~i~PrimaryBleedandFeed(PBF)ContainmentSprayIrjection(CSQManuallyopen2of3PORVsandblockvalves,1of2SIand1of2CCpumps1of2TrainsElectricPower,CCWtoSIandCCpumps,ControlAir,PressurizerPORVsElectricalPower,Hi-HiContainmentpressuresignalOpen2of3PORVsandblockvalves.StartpumpsorverifypumpsrunmngNone0.50.54,33 TABLE3.1-9(Cont'd.)TRANSIENTSWITHOUTSTEAMCONVERSIONSYSTEMSAVAILABLESYSTEMSUCCESSCRITERIAEventTree$~~~HighPressureColdLegRecirculation(HPR)ContainmentSprayRecirculation(CSR)HydrogenIgniters(Hl)EquipmentSuccess~rit~ri1of2RHRtrainssupplying1of2SIand1of?CCpumps,to1of3intactlegs1of2CStrainsswitchedfromtheRWSTtotherecirculationsump1of2trainsinbothupperandlowercontainmentSystemD~gnnfgnn;i~ComponentCoolingWater,ElectricalPower,RHRElectricalPower,EssentialServiceWaterElectricalPowerOperator~Ai~~ManualvalvechangesinSlsystemIsolateRWSTOpensumpvalvesRestartpumpsManualvalve.changesinCSsystem,pumpsrestartedEnergizeIgnitersMissionT~imhr~Rf~~n~4,331,4EngineeringJudgementContainmentRecirculationFans(CF)1of2trainsoperatingElectricalPowerhHi-HiContainmentPressureSignalCCWNoneEngineeringJudgement~Conservativelyassumedonlythreecoldlegsavailabletominimizethenumberoffaulttreestobedeveloped.ThissuccesscriteriaisconsistentwiththeLOCAsuccesscriteria.341 TABLE3.1-10LARGESTEAMLINE/FEEDLINERUPrURESYSTEMSUCCESSCR1TERIAEventTreeSatanECCS(ChargingPump)Iqjection/Boration(HP3)EquipmentSuccess~ri~ri1of?CCPsto1of4loopswithBorationfromB1TSystemDK~nÃ~ElectricPower,SISignal,ComponentCoolingWaterOperator/~i~NoneMissionY~imhrR~fg~n~051SecondarySideIsolation(MS1)AuxiliaryFeedwaterActuationwithSteamLineRupturePrimaryBleedandFeed(PBS)Shut3of4MSIVs600gpmAFWfiowto2of3intactsteamgeneratorsAFWisolatedtofaultedsteamgeneratorManuallyopen2of3PORVsandblockvalves,1of2SIand1of2CCpumpsElectricPower,IsolationSignalElectricPower,StartSignalElectricPower,CCWtoSIandCCpumps,ControlAir,PressurizerPORVsNoneProvideadditionalwatersupplyondepletionofCST,f(AFS)IsolatefaultedS/GOpen2of3PORVsandblockvalves.StartpumpsorverifypulnpsrunlllngN/A0.51&EngineeringJudgement4,33 TABLE3.1-10(Cont'd.)LARGESTEAMLINE/FEEDLINEBREAKSYSTEMSUCCESSCRITERIAEventTree$gitalContainmentSprayInjection(CSI)EquipmentSuccess1of2TrainsSystemDggn+~ni~ElectricalPowerpHi-HiContainmentpressuresignalOperatorWAbmmNoneMissionT~imgag~Rf~~n~0.51HighPressureColdLegRecirculation(HPR)ContainmentSprayRecirculation(CSR)1of2RHRtrainssupplying1of2SIand1of2CCpumps,to1of3intactlegs1of2CStrainsswitchedfromtheRWSTtotherecirculationsumpComponentCoolingWater,ElectricalPower,RHRElectricalPower,EssentialServiceWaterManualvalve24changesinSIsystemIsolateRWSTOpensumpvalvesRestartpumpsManualvalve24changesinCSsystem,pumpsrestarted4,33Conservativelyassumedonlythreecoldlegsavailabletominimizethenumberoffaulttreestobedeveloped.ThissuccesscriteriaisconsistentwiththeLOCAsuccesscriteria.

TABLE3.1-10(Cont'd.)LARGESTEAMLINE/FEEDLINEBREAKSYSTEMSUCCESSCRHXRIAEventTree5xsftmiHydrogenIgniters(HQContainmentRecirculationFans(C$)EquipmentSuccess~ri~ri1of2trainsinbothupperandlowercontainment1of2trainsoperatingSystem;~D~n~nElectricalPowerElectricalPowersHi-HiContainmentPressureSignal,CCWOperatorgatiEnergizeIgnitersNoneMissionT~imger~R~frt~n~EngineeringJudgementEngineeringJudgement TABLE3.1-11LOSSOFOFFSITEPOWERSYSTEMSUCCESSCRITERIAEventTree5xatmAuxiliaryFeedwaterActuation(AFI)EquipmentSuccess~ri~ri450gpmAFWfiowto2of4steamgeneratorsSystemDgg~~nEledricPower,StartSignalOperator~A~iProvideadditionalwatersupplyondepletionofCSTMissionT~imhr~RfrRr~PrimaryBleedandFeed(PBF)ContainmentSprayIqjedion(CSQManuallyopen2of3PORVsandblockvalves,1of2SIand1of2CCpumps1of2TrainsElectricPower,CCWtoSIandCCpumps,ControlAir,;PressurizerPORVsEledricalPower,Hi-HiContainmentpressuresignalOpen2of3PORVsandblockvalves.StartpumpsorverifypunlpsrunIllngNone0.50.54,33345 TABLE3.1-11(Cont'd.)LOSSOFOFFSITEPOWERSYSTEMSUCCESSCRITERIAEventTree5xsfmEquipmentSuccess~rigraniSystemD~~~i~Operator~A~iMission~Timirr~HighPressureColdLegRecirculation(HPR)1of2RHRtrainssupplying1of2SIand1of2CCpumps,to1of3intactlegsComponentCoolingWaterEledricalPowerRHRManualvalve?AchangesinSIsystemIsolateRWSTOpensumpvalvesRestartpumps4,33ContainmentSprayRecirculation(CSR)1of2CStrainsswitchedfromtheRWSTtotherecirculationsumpElectricalPowerEssentialServiceWaterManualvalve24changesinCSsystem,pumpsrestartedHydrogenIgniters(HI)1of2trainsinbothupperandlowercontainmentElectricalPowerEnergizeIgnitersEngineeringJudgementContainmentRecirculationFans(CF)1of2trainsoperatingElectricalPowersHi-HiContainmentPressureSignal,CCWNoneEngineeringJudgement~Conservativelyassumedonlythreecoldlegsavailabletominimizethenumberoffaulttreestobedeveloped.ThissuccesscriteriaisconsistentwiththeLOCAsuccesscriteria.

TABLE3.1-12STATIONBLACKOUTSYSTEMSUCCESSCRITERIAEventTreeEquipmentSuccess~ri~itSystemDgggnnngi~Operator~tit~MissionT~imhrR~Fj,~n~Turbine-DrivenAuxiliaryFeedwaterPump(AFI')Turbine4rivenpumpdeliversflowto2SgsN-TrainBattery,ESFASSignalVerification439ormanualstartingofpumpRCSCooldown(RCD)AuxiliaryFeedwaterContinues(AFC)RCScooleddownby2of4steamgeneratorsPORVs-Startwithin60min.Turbine4rivenpumpcontinuestodeliverflowto2of4S/Gsforanadditional2hourspastAFI'issiontime.MainSteam,NitrogenNoneOpenS/GPORV's,depfessurizeS/Gsto200psigwithin2hoursafterSBOVeriTication33,39393-47 TABLE3.1-12(Cont'd.)STATIONBLACKOUTSYSTEMSUCCESSCRITERIAEventTree5xslmEquipmentSuccess~ri~riSystemQ~~~nii~Operator+~iMissionT~imhr~Qjy~n~PowerRestoredWithinXHours(XHR)PowerrestoredtoACpowersystemwithinXhours,XisdefineinReference47.NoneN/A33,39Verificationormanualstartingofdieselgenerator,variousmanualbreakeralignments,restartmotorsCoreNotUncovered(CNU)CorenotuncoveredafterpowerisrestoredNoneNoneN/A39RestoreRCSInventory(RRI).Restoresafeguardssystems,initiateSIwith1of4SIorCCpumpsdeliveringtotheRCSElectricPower,CCWRestoresystems,startpumps1,39AuxiliaryFeedwaterActuation(AF1)450gpmAFWflowto2of4steamgeneratorsElectricPowerProvideadditionalwatersupplyondepletionofCSI',Startpumps33 TABLE3.1-12(Cont'd.)STATIONBLACKOUTSYSTEMSUCCESSCRITERIAEventTreestanPrimaryBleedandFeed(PB$)EquipmentSuccess~riaprilManuallyopen2of3PORVsandblockvalves,1of2SIand1of2CCpumpsSystemD~~nl~ni~ElectricPower,CCWtoSIandCCpumps,ControlAir,PressurizerPORVsOperatorQ~tiOpen2of3PORVsandblockvalves.StartpumpsorverifypulnpsfunningMission~Timhr~Rf~rnRi0.54,33ContainmentSpraybisection(CSI)1of2TrainsElectricalPowerStartsystem0.5~HighPressureColdLegRecirculation(HPR)ContainmentSprayRecirculation(CSR)1of2RHRtrainssupplying1of2SIand1of2CCpumps,to1of3intactlegs1of2CStrainsswitchedfromtheRWSTtotherecirculationsunlpComponentCoolingWaterElectricalPowerRHRElectricalPowerEssentialServiceWaterManualvalve24changesinSlsystemIsolateRWSTOpensumpvalvesRestartpumpsManualvalve24changesinCSsystemppunlpsrestarted4,33~Conservativelyassumedonlythreecoldlegsavailabletominimizethenumberoffaulttreestobedeveloped.ThissuccesscriteriaisconsistentwiththeLOCAsuccesscriteria.349 TABLE3.1-12(Cont'd.)STATIONBLACKOUTSYSTEMSUCCESSCRITERIAEventTree~@nHydrogenIgnitersgiQEquipmentSuccesspriori~1of2trainsinbothupperandlowercontainmentSystemDg~ni~ii~ElectricalPowerOperator~A+i~EnergizeIgnitersMissionT~imhr~Rf~r~nEngineeringJudgementContainmentRecirculationFans(CFj1of2trainsoperatingElectricalPowerpHi-HiContainmentPressureSignal,CCWNoneEngineeringJudgement TABLE3.1-13ANTICIPATEDTRANSIENTWITHOUTSCRAMSYSTEMSUCCESSCRITERIAEventTree$~~ReducedPowerLevel(RPL)EquipmentSuccess~ri~riTransientInitiatedFromLessThan"40%PowerSystemD~~~i~NoneOperator~AggngNoneMissionY~imhr~Rf~~n~N/A42ManualRodInsertion(MRI)OneMinuteofManualRodInsertionWithinOneMinuteElectricPowerManuallyInsertControlRodsN/A42AMSAC(AMS)AuxiliaryFeedwaterActuation(AF1)TripTurbineandGenerateaSignaltoStartAFWPumps450gpmAFWflowto2of4steamgeneratorsElectricPowerElectricPower,StartSignalNoneProvideadditionalwatersupplyondepletionofCSTN/A42423-51 TABLE3.1-13(Cont'd.)ANTICIPATEDTRANSIENTWITHOUTSCRAMSYSTEMSUCCESSCRITERIAEventTree@~tern900gpmAuxFeedwaterFlow(AFH)EquipmentSuccessgriterig900gpmAFWFlowto2of4SteamGeneratorsSystemD~eendenciElectricPower,StartSignalOperatorActiorgProvideadditionalwatersupplyondepletionofCSTMissionT~imtrrR~eFrdnnctPrimaryPressureRelief(PPR)Nounfavorableexposuretime,3of3SafetyValves,andeither:a)3of3PORVsifMRIissuccessful,or:b)1of3PORVsifMRIfails.ElectricPower,ControlAirOpenBlockValvesifNece.mry2442LongTermShutdown(LTS)1of2CCPsorestablishsubcriticalitybyotherthanborationElectricPower,CCWTripControlRod24MotorGeneratorSets,LocallyOpenReactorTripBreakers,Manuallyinsertallcontrolrodsfully,orinitiateboration4,42 TABLE3.1-13(Cont'd.)ANTICIPATEDTRANSIENTWITHOUTSCRAMSYSTEMSUCCESSCRITERIAEventTreeSntmContainmentSprayIqjection(CSI)ContainmentSprayRecirculation(CSR)HydrogenIgniters(Hi)EquipmentSuccess~rigrani1of2Tf8lns1of2CStrainsswitchedfromtheRWSTtotherecirculationsump1of2trainsinbothupperandlowercontainmentSystemDggn+~i~ElectricalPower,Hi-HiContainmentpressuresignalElectricalPower,EssentialServiceWaterElectricalPowerOperator~Ai~NoneManualvalvechangesinCSsystem,pumpsrestartedEnergizeIgnitersMissionT~imhrR~fg~n~0.511,4EngineeringJudgementContainmentRecirculationFans(CF)1of2trainsoperatingElectricalPower,Hi-HiContainmentPressureSignal,CCWNoneEngineeringJudgement3-53 TABLE3.1-14LOSSOFESSENTIALSERVICEWATERSYSTEMSUCCESSCRITERIAEventTreeatmTripRCPs(RCP)AuxiliaryFeedwaterActuation(AF1)MainFeedwater(MF1)EquipmentSuccessG@maAllRCPstrippedfollowinglossofsealcooling450gpmofAFWflowto2outof4steamgenerators1outof2mainfeedwaterpumpsto2of4SGs-or450gpmAFWfromtheoppositeUnitto2of4SGsSystemD~~nl~ni~NoneElectricPowerElectricPowerCondensate,MainSteam-Operator+~iTripRCPsuponlossofsealcoolingProvideadditionalwaterwatersupplyondepletionofCSTDefeatMFWpumptripandMFWisolationsignalsStartplBllpspManualvalvechangestoalignsystemsMissionT~imhrN/AR~f~n39&EngineeringJudgement394,39RestoreESWSystemWithinOneHour(EH1)RestorationofflowtooneESWheaderNoneRestoresystem(onetrain)4,39 TABLE3.1-14(Cont'd.)LOSSOFESSENTIALSERVICEWATERSYSTEMSUCCESSCRITERIAEventTree~fgg1EquipmentSuccess~ri~riSystemDgg~n~ni~Operator~AtirgMissionT~imhr~Rf~n~RCSCooldown(RCD)RestoreESWSystemWithinEightHours(EHS)RCScooldownby2of4S/GPORVs-startwithin60minutesRestorationofflowtooneESWheaderEledricPower,ControlAirMainSteamNoneOpenS/GPORVs,24depressurizeS/GtoinitiateRCScooldownRestoresystem8(onetrain)33,394,39CoreNotUncovered(CNU)CorenotuncoveredafterESWcoolingisrestoredNoneNoneN/A39RestoreRCSInventory(RRI)Restoresafeguardssystemsusing1of4SUCCpumpsto3/4RCScoldlegsElectricPower,CCWRestoresystems,24startpumps4,39ContainmentSprayIqjection(CSI)1of2CSpumpsElectricPower,Hi-HiContainmentPressureSignalNone0,53-55 TABLE3.1-14(Cont'd.)LOSSOFESSENTIALSERVICEWATERSYSTEMSUCCESSCRITERIAEventTree5xstmEquipmentSuccess~rigraniSystemDt,ggn+~ni~Operator~AtingMissionT~imh~r~HighPressureColdLegRecirculation(HPR)1of4SIorCCPpumps1/2RHRtrainsElectricPower,CCW,RHRManualvalve24changesinSIsystem,isolateRWST,aligncoolingwatertoHX,opellsunlpvalvespstartpumps4,33ContainmentSprayRecirculation(CSR)1of2CTSpunlpsSump&HXElectricPower,EssentialServiceWater,Hi-HiContainmentPressureSignalManualvalve24changesppumpsrestartedHydrogenIgniters(Hi)1/2trainsoperatingElectricPowerEnergizeIgnitersEngineeringJudgementContainmentRecirculationFans(CFI1/2ContainmentRecirculationFanTrainsElectricPower,Hi-Hi.ContainmentPressureSignal,CCWNoneEngineeringJudgement~Conservativelyassumedonlythreecoldlegsavailabletominimizethenumberoffaulttreestobedeveloped.ThissuccesscriteriaisconsistentwiththeLOCAsuccesscriteria.

TABLE3.1-15LOSSOFCOMPONENTCOOLINGWATERSYSTEMSUCCESSCRITERIAEventTreeTripRCPs(RCP)AuxiliaryFeedwaterActuation(AF1)MainFeedwater(MFI)RestoreCCWSystemWithinOneHour(CH1)EquipmentSuccessAllRCPstrippedfollowinglossofsealcooling450gpmofAFWflowto2outof4steamgenerators1outof2mainfeedwaterpumps.to2of4SGs-or450gpmAFWfromtheoppositeUnitto2of4SGsRestorationofflowtooneCCWheaderSystemDgg~nNoneElectricPowerElectricPowerCondensate,SteamNoneOperator~Ai~TripRCPsuponlossofsealcoolingProvideadditionalwaterwatersupplyondepletionofCSTDefeatMFWpumptripandMFWisolationsignalsStartpumpspManualvalvechangestoalignsystemsRestoresystem(onetrain)MissionT~imhrN/A~Rfrt,n~~39&EngineeringJudgement394,394,393-57 TABLE3.1-15(Cont'd.)LOSSOFCOMPONENTCOOLINGWATERSYSTEMSUCCESSCRITERIAEventTreeEquipmentSuccessgrii~rilSystemDg~l~~Operator~AtingMission~Tim~r~RRCSCooldown(RCD)RCScooldownby2of4S/GPORVs-startwithin60minutesElectricPower,ControlAir,MainSteamOpenS/GPORVs,24depressurizS/GtoinitiateRCScooldown33,39RestoreCCWSystemWithinEightHours(CH8)RestorationofflowtooneCCWheaderNoneRestoresystem8(onetrain)4,39CoreNotUncovered(CNU)CorenotuncoveredafterCCWcoolingisrestoredNoneNoneN/A39RestoreRCSInventory(RRI)Restoresafeguardssystemsusing1of4SVCCpumpsto3/4RCScoldlegsElectricPower,CCWRestoresystems,24startpump4,39ContainmentSprayInjection(CSI)1of2CSpumpsElectricPower,Hl-HiContainmentPressureSignal,None0.5 TABLE3.1-15(Cont'd.)LOSSOFCOMPONENTCOOLINGWATERSYSI'EMSUCCESSCRITERIAEventTreeEquipmentSuccess~rigr~iSystemDggn+~ciOperator~A~iMission~Tim0u+~Rfg~n~~~HighPressureColdLegRecirculation(HPR)1of4SIorCCPpumps1QRHRtrainsElectricPower,CCW,RHRManualvalve24changesinSIsystem,isolateRWST,aligncoolingwatertoHX,opensumpvalves,startpumps4,33ContainmentSprayRecirculation(CSR)1of2CTSpumpsSump&HXElectricPower,EssentialServiceWater,Hi-HiContainmentPressureSignalManualvalve24changesppumpsrestartedHydrogenIgniters(Hl)1QtrainsoperatingElectricPowerEnergizeIgnitersEngineeringJudgementContainmentRecirculationFans(CF)1QContainmentRecirculationFanTrainsElectricPowerCCWNoneEngineeringJudgement~Conservativelyassumedonlythreecoldlegsavailabletominimizethenumberoffaulttreestobedeveloped.ThissuccesscriteriaisconsistentwiththeLOCAsuccesscriteria.3-59 TABLE3.1-16LOSSOFSINGLETRAINOF250VDCELECTRICPOWERSYSTEMSUCCESSCRITERIAEventTree5xsttmAuxiliaryFeedwaterActuation(AF1)EquipmentSuccess~rigrani450gpmAFWflowto2of4steamgeneratorsSystem~De~nn~i~ElectricPower,StartsignalOperator~Ati~ProvideadditionalwatersupplyondepletionofCSI'issionT~imh~rUnit2AFWCrosstie(2AV)450gpmUnit2AFWflowto2of4steamgeneratorsElectricPowerOpencrosstie24valve,isolateUnit2S/Gs,startUnit2AFWpumpContainmentSprayEjection(CSI)1of2trainsEledricalPower,HIHIcontainmentpressuresignalNone0.5ContainmentSprayRecirculation(CSR)1of2CStrainsswitchedfromtheRWSTtotherecirculationsumpElectricalpowerEssentialServiceWaterManualvalve24changesinCSsystem,pumpsrestarted03400:

TABLE3.1-16(Cont'd.)LOSSOFSINGLETRAINOF250VDCELECTRICPOWERSYSTEMSUCCESSCRITERIAEventTree5mfmHydrogenIgniters(HQContainmentRecirculationFans(CF)EquipmentSuccess~ri~ll1of2trainsinbothupperandlowercontainment1of2trainsoperatingSystemD~g~n~i~ElectricalpowerElectricalpowerHi-Hicontainmentpressuresignal,CCWOperator+gg~EnergizeIgnitersNoneMissionT~imhr~Rf~nEngineeringJudgementEngineeringJudgement3-61 TABLE3.1-17INTERNALFLOODINGSYSTEMSUCCESSCRITERIAEventTree5xatmAuxiliaryFeedwaterActuation(AF1)EquipmentSuccess~rit~eriI450gpmAFWflowto2of4steamgeneratorsSystem~Den~dni~ElectricPower,StartSignalOperatorActi~,ProvideadditionalwatersupplyondepletionofCSTMission~Timhr~Rfg~n~PrimaryBleedandFeed(PBS)ContainmentSprayInjection(CSQManuallyopen2of3PORVsandblockvalves,1of2SIand1of2CCpumps1of2TrainsElectricPower,CCWtoSIandCCpumps,ControlAir,.PressurizerPORVsElectricalPower,Hi-HiContainmentpressuresignalOpen2of3PORVsandblockvalves.StartpumpsorverifypumpsfunlllngNone0.50.54,33 TABLE3.1-17(Cont'd.)INTERNALFLOODINGSYSTEMSUCCESSCRITERIAEventTreeEquipmentSuccess~ri~qSystem~De~~iceOperator~AingMissionT~imhr~Rf~rt;n~~~HighPressureColdLegRecirculation(HPR)ContainmentSprayRecirculation(CSR)1of2RHRtrainssupplying1of?SIand1of2CCpumps,to1of3intactlegs1of2CStrainsswitchedfromtheRWSTtotherecirculation"sunlpComponentCoolingWater,ElectricalPower,RHRElectricalPowersEssentialServiceWaterManualvalvechangesinSIsystemIsolateRWSTOpensumpvalvesRestartpumpsManualvalvechangesinCSsystem,pumpsrestarted4,331,4HydrogenIgnitexs(HI)1of2trainsinbothupperandlowercontainmentElectricalPowerEnergizeIgnitersEngineeringJudgementContainmentRecirculationFans(CS)1of?trainsoperatingElectricalPower,Hi-HiContainmentPressureSignalCCWNoneEngineeringJudgemerit~Conservativelyassumedonlythreecoldlegsavailabletominimizethenumberoffaulttreestobedeveloped.ThissuccesscriteriaisconsistentwiththeLOCAsuccesscriteria.

3.12SpecialEventTreesI,.Severalspecialeventtreesweremodelledtoaccommodateconsequentialeventsandsupportsystemfailures.Theseeventtreesareincludedintheabovediscussion.'.1.4SupportSystanEventTreeBecausetheCookNudearPlantIPEusesfaulttreelinkingtoquantifytheaccidentsequences,nosupportsystemeventtreesweredeveloped.Thefaulttreelinkingmethodrequiresthedevelopmentofasystemfaulttreeforeachofthefront-linesystemsandforeachofthesupportsystemsmodeled.Eachfront-linesystemfaulttreecallsintheappropriatesupportsystemfaulttreeortreesandthelinkingprocessproperlyquantifiestheaccidentsequenceswithoutdoublecountingsupportsystems.3.1.5SequaxxGroupingandBack-EndInterfaceTheprimaryfocusoftheeventtreeanalysiswastoprovideaquantifiablemodelofthesafeguardsandcontainmentprotectionsystemsfortheLevelIIanalysis.Eachsequenceintheeventtreethatresultedincoredamagewasidentifiedbyaseriesofdescriptorsthatindicatedthetypeofevent,stateoftheprimarysystem,andstateofcontainmentprotectionsystems.ThesedescriptorswerethenusedtogroupsimilarcoredamagestatesfortheLevelIIanalysis.Thefirstcharacterinthedescriptorisoneofthefollowing:ALargeLOCA-CharacterizedbyrapiddepressurizationoftheRCSandsubsequentcoreuncovery.SSmallLOCA-CharacterizedbyasmallbreachoftheRCSpressureboundaryresultingina')~directreleasepathtothecontainment.RCSdepressurizationisexpectedtobelimitedbythesizeofthebreakandmayevenstallatrelativelyhighpressurelevels.TTransient-AneventwhichisnotinitiatedbyabreachoftheRCSpressureboundary.Eventsinthiscategoryarecharacterizedbytheopeningofpressurizersafetyorreliefvalveswiththeassociatedlossofprimarycoolantsubsequenttothe.eventinitiation.GSteamGeneratorTubeRupture-Thiseventisinitiatedbythefailureoftheprimarytosecondarypressureboundaryofonesteamgenerator.Inthisevent,primarycoolantmaybelostthroughsteamconversionsystemsresultinginadirectreleaseofradionuclidestotheenvironment.VInterfacingSystemsLOCA-ThiseventischaracterizedbyabreachoftheRCSpressureboundary,whichdirectlybypassesthecontainment(otherthanthesteamgeneratortuberupture).Sinceprimarycoolantislostoutsidethecontainment,norecirculationcapabilityexistsandnowaterisinthecontainmenttoprovideforfissionproductscrubbingfollowingcoremelt.Thisresultsinalargereleaseofradionuciidesoutsidethecontainmentbuilding.Thesecondcharacterisoneofthefollowing:HRCSatHighPressure-Indicatingthat,whenvesselfailureoccursfollowingcoredamage,theRCSisathighpressure,generallytakentobeabove200psig.LRCSatLowPressure-Indicatingthat,whenvesselfailureoccursfollowingcoredamage,theRCSisatlowpressure,generallytakentobebelow200psig.)344 Followingthefirsttwocharacters,thefollowingcharactersmaybeusedeitheraloneorincombinationtoclassifythestatusofthecontainmentandthecontainmentprotectionsystems:W,TheRWSTinventoryhasnotbeenemptiedintocontainmentindicatingthatthereactorcavityisdry+CContainmentsprayinjectionwassuccessful,however,containmentsprayrecirculationwasdisabled.RContainmentsprayirjectionandrecirculationweresuccessful.IHydrogenIgniterSystemfailure.FContainmentRecirculationFansystemfailure.Thosesequencesthatdonotresultincoredamageareidentifiedbyoneofthefollowingtwodescriptors;SUCCESSCoredamagewaspreventedandthecontainmenteitherremainedintactorwasnotchallenged.LEAKCoredamagewasprevented,however,abreachofthecontainmentresultedinalossofprimarycoolanttotheoutsideatmosphere.Nobinningofplantdamagestateswasdoneinthefrontendportionoftheanalysisotherthantoassignthedescriptorsdescribedabove.AllbinningofplantdamagestateswasdoneintheLevel2portionoftheanalysis.TheprocessofbinningisdescribedinSection4.6ofthisreport.345 3DSystemsAnalysisTodevelopanunderstandingofthecontributionofsystemperformancetoaccidentsequencesandtoquantifytheeventtrees,acomprehensiveanalysisofallkeyplantsystems(fromariskperspective)wasperformed.Thisactivityincludedaplantfamiliarizationactivitywhichisdocumentedinsystemnotebooks,anexhaustivesearchfordependenciesbetweenplantsystems,anddetailedfaulttreeanalysisforeachkeysystem.Technicalguidelineswerepreparedforeachoftheseactivitiestoassurethataconsistent,thoroughapproachwasemployedbyallanalyststhroughouteachstageofthework.Theseguidelinesalsoservedasreferencesthatdocumentedthemethodsused.Thissectionprovidesanoverviewofthemethodsusedintheplantsystemsanalysisactivity.0)32.1SystemDescriptionsToensurethattheIPEaccuratelyrepresentedhowtheplant'ssystemscontributetotheoverallriskprofile,athoroughunderstandingofkeyfrontlineandsupportsystemswasessential.Priortothedevelopmentofthefaulttreelogicmodels,acomprehensivecollection,evaluation,anddocumentationofinformationwasperformedforeachsystem.Thisinformationwasconsolidatedintoasinglereferencenotebookforeachsystem.TheoutlineusedforeachofthesesystemnotebooksisgiveninTable3.2-1.Thefirstsixsectionsofthesystemnotebookscontaintheessentialplantdesignandoperationalinformationneededtodevelopthefaulttrees.IncludedinthesesectionsaretheimportantdependenciesreflectedinthematricesdescribedinSection3.2.3ofthisdocument,instrumentationandcontrolrequirements,andtheresultsofacomprehensivereviewofequipmentmaintenanceandsurveillancepractices.Theplantwalkdown,describedinSection2.4ofthisreport,wasusedtoverifythatthesystemmodelaccuratelyreflectedthesystemconfigurationandoperatingconditions.Theresultsofathoroughoperatingexperiencereviewarealsodocumented.Thisinformationwasusedtobesurethatplantspecificoperatingexperienceisreflectedinthemodeldevelopmentandinthequantificationofsystemandcomponentperformanceparameters.Section7containsthelogicmodelsandtheassumptionsusedtoconstructthefaulttrees.Section8providestheresultsofthemodelquantificationandSection9identifiestheinsightsrelatedtothatsystemthatweredevelopedduringthecourseoftheIPE.BecausetheCookNuclearPlantisadualunitsite,acarefulexaminationofthedocumentationforbothunit'ssystemswasperformed.Anykeydifferenceswereidentifiedandexplicitlydocumentedinthesystemnotebooks.Sharedsystemsorcomponentswereidentified,includingthedegreeofsharingandthesystems'referentialalignments.Anyunit-to-unitcrossties,alongwiththenormalalignmentandemergencyalignmentcapabilities,wereidentified.Plantoperating,surveillanceandmaintenanceprocedureswerereviewed.Table3.2-2liststhesystemsmodeledintheCookNuclearPlantIPE.Theremainderofthissectionprovidesabriefdescriptionofthesesystemsandtheirimportantdesignfeaturesfromariskperspective.ThesymbolsusedinthesimplifiedflowdiagramsforthesesystemsareshowninFigure3.2-1.

1.0SYSTEMFUNCTIONTABLE321OUTLINEFORSYSrEMNO'rEBOOKS2.0SYSTEMDESCRIPl'ION2.1SupportSystems2,2InstrumentationandControls2.3TechnicalSpecificationLimitations2.4TestandMaintenance2,5,ComponentLocation2.6ComparisonofUnits3,0SYSTEMOPERATION4.0PERFORMANCEDURINGACCIDENTCONDITIONS4.1SuccessCriteria4,2InitiatorImpactontheSystem5.0OPERATINGEXPERIENCE6.0INITIATINGEVENTREVIEW7.0SYSTEMLOGICMODELS7.1AssumptionsandBoundaryConditions7.2FaultTreeModels8,0QUANTIFICATIONANDRESULTS9.0SYSTEMINSIGHTS

10.0REFERENCES

APPENDICESA.CommonCauseCalculationsB.ComputerCodeInputandOutputC.SupportingTechnicalInformation347 TABLE3&2SYPIZMSMODELLEDINTHECOOKNUCLEARPLANTIPRSection3.2.1.1Section3.2.1.2Section3.2.1.3Section3.2.1.4Section3.2.1.5Section3.2.1.6Section3.2.1.7Section3,2.1.8Section3.2.1.9Section3.2.1.10Section3,2.1.11Section3.2.1.12Section3.2.1.13Section3.2.1.14AuxiliaryFeedwaterSystemContainmentSpraySystemComponentCoolingWaterSystemEssentialServiceWaterSystemNonessentialServiceWaterSystemCompressedAir(ControlAir)SystemEmergencyCoreCoolingSystem(Includingsafetyirjection/charging,residualheatremoval,andaccumulators)ElectricPowerSystem(Including4160VAC,600VAC,120VACand250VDC)MainFeedwaterandCondensateSystemsMainSteamSystemPressurizerPowerOperatedReliefValveandSafetyValveSystemContainmentAirRecirculationandHydrogenSkimmerSystemHydrogenIgniter(DIS)SystemRefuelingCanalDrains0)348 VAVPNVAVC~VA~V~G4TETYP~GATETYPTHREE-vAYPAIIALLELDISCGATE~PAIIALLEI.DISCGATEgSAI'ETTII~GLOBElBALL)BUTTERPLY~lNEDLE~DIAPHRAGHGl.OBE<BAL'BUTTERPLzIHDIAPHRAGH~CHECK'NQSTQPALECKIIANGLElANGI-TYPEg]AIRSOLENOIDCOCKELECTRICMOTORTYPE,STEHLE4KOI'PEOUALIZINGCONNECTIQN<PORPARALLLDISCG4TEvALvES>AlRPISTONPROCESSACTUATEDVALVEOPERATORSVALVECONNECTiONSOTHERSYPEP~HEATEXCHANGERPUMPIIGRIPICETURBINE8T'LCVSVITCH~EDUCTQRROCESSACTUATEDID~ISIO'K~StPANFigure3.2-1HowDiagramComponentSymbols3-69 32.1.1AuxiTiaryFeatwaterSystemTheprimaryfunctionoftheauxiliaryfeedwater(AFW)systemistoprovidesufficientmakeuptothesteamgeneratorstomaintainaminimumheattransferareatopreventlossofprimarywaterthroughthepressurizersafetyorreliefvalveswhennormalfeedwatersupplyisnotavailable.FortheIPEanalysis,theAFWsystemistheprimarysourceofwatertothesteamgeneratorswhenthesteamgeneratorsareusedtoremovelatentordecayheatfromthereactorcoolantsystem(RCS)andthecore.Additionally,theAFWsystemisusedtosupplythesteamgeneratorsduringstartupandshutdownwheninsufficientsteamisavailableforthemainfeedwaterpumps,however,thisfunctionisnotmodelledinthisstudy.Figure3.2-2showsasimplifiedfiowdiagramofthesystem.Theprimarysourceofwaterforthesystemistheunit's500,000galloncondensatestoragetank(CST).Anemergencybackupsupplyisavailablefromtheoppositeunit'sCSTthroughnormallydosedcondensatestoragetankcross-tievalve,12-CRV-51.Ifbothunit'sCSTsareunavailable,thenthesystemmaybealignedtotakesuctionfromtheessentialservicewater(ESW)systembut,thisisonlyusedafterallothersourcesofcondensatehavebeenexhausted.AFWflowisdeliveredtothesteamgeneratorsbythreepumps,oneturbine-drivenauxiliaryfeedwaterpump(TDAFP),andtwomotor-drivenauxiliaryfeedwaterpumps(MDAFP).Eachpumphasitsownsuctionstraineranddischargeisolationandcheckvalves.TheTDAFPiscapableofsupplyingallfoursteamgenerators.TheeastMDAFPsuppliesonlysteamgeneratorstwoandthree,andthewestMDAFPsuppliesonlysteamgeneratorsoneandfour.AcrosstiebetweenunitsisprovidedbetweentheeastMDAFPdischargeisolationandcheckvalves.Thisline,normallyisolatedbylockeddosedvalve,FW-129,providestheabilityforoneunit'seastMDAFPtosupplytheoppositeunit'ssteamgeneratorsnormallysuppliedbythewestMDAFPandviceversa.Thereareninemodels(faulttrees)associatedwiththeAuxiliaryFeedwaterSystem.Eachmodelrepresentstheunavailabilityofthissysteminresponsetodifferentaccidentevents.~)AF1-ThissystemmodeldefinethelogicassociatedwiththeresponseoftheAFWsystemtoprovideatleast450gpmofflowtoatleasttwooffoursteamgenerators.AFS-ThissystemmodeldefinesthelogicassociatedwiththeresponseoftheAFWsystemtoprovideatleast600GPMofflowtoatleasttwoofthethreeintactsteamgeneratorsfollowingalargesteamline/feedlineruptureevent.AFI'-ThissystemmodeldefinesthelogicassociatedwiththeresponseoftheAFWsystemtoprovideflowfromtheTDAFPtoatleasttwooffoursteamgeneratorsduringastationblackoutevent.AFH-ThissystemmodeldefinesthelogicassociatedwiththeresponseoftheAFWsystemtoprovideatleast50%capacityfiowtothesteamgenerators.AF2-ThissystemmodeldefinesthelogicassociatedwiththeresponseoftheAFWsystemduringaSGTReventtoprovideflowfromatleastoneofthreepumpstoatleastoneofthreeintactsteamgenerators.AB-ThissystemmodeldefinesthelogicassociatedwiththeresponseoftlieAFWsystemduringaSGTReventtoprovideflowfromoneoftwopumpstothefaultedsteamgenerator.AFC-ThissystemmodeldefinesthelogicassociatedwiththeresponseoftheAFWsystemtoprovideflowtoatleasttwooffoursteamgeneratorsforanadditionaltwohoursaftertheN-Trainbatteryisassumedlost.3-70 AF4-ThissystemmodeldefinesthelogicassociatedwiththeresponseoftheAFWsystemtoprovideatleast450gpmofflowtoatleasttwooffoursteamgeneratorsduringLOCAscenarios.2AF-ThissystemmodeldefinethelogicassociatedwiththeresponseoftheAFWsystemtoprovideatleast450gpmofAFWflowtoatleasttwooffoursteamgeneratorsthroughuseoftheunitcross-tieconnections.3-71 INSIDCDIIISITCRCACIORRCACIORCONTAHRCNTICOIIAltNQITFVI)1Ifv.l)l.lI'V1)I~fv1)1~H2HS-II8.2HS148)FVl)1)fvI)1)rv-I)I-2SIFI'V-131-2IIIfv-l)8IFHO.tllIN'"-HglAIN~fv1stIflCItltIIIfv-l)t~FICI242K*.""'~~F15~IfVI)0~FHOtIIIIRV'ROIpgHIIR""~I'v-l)0)fHQ2)lIIIfv-I)t-)1ICI-t)2Ig4IMICAHtgR*IOI~IV-l)ttfHOtttIk<Iv-1)0-2FNO-ttlIfvISDNgFV13CNg(FRfv-130fVI)I'RvtISVVIVIfVIVtrv-I40fRV-255ZabVH0SPP)V00~CN0SPP)CfvIt6LaCSV-24'SV24)FROICSVSTSTCHrv-ICIrv-lctCSV114CSVIISFROICSVS'TSTCHFVI)IFvI))SIFLSLCSY116CSV-10)FROICSVVHOTSALCSTSICHFv121FvIt)HAKCIFTDCOISCNSCRSLCKCCSSfLOV10STORAOCCSTTK)2nIbICH~0NfCAVSl~ALVCNOTATIOIDCFINIITOISa.HeNRHIALLTOFTEN~1(LOSfD2.A~VALVCIFCNSAOIOIAIICALLYOIAUIOIATICSTARTOr11$ASIOCIAICDAFVPIPPRCfCRCNCCDRAVINGQ00I-SI06AICIF-2-5106A15O'-I5101)SIF2510130OPI5141A-11OP25101A23Figure3.2-gAuxiliaryFeedwaterSystemSimplifiedHowDiagram3-72 3.2.1.2ContainmentSpraySystemThecontainmentspray(CTS)systemisrequiredintheeventofalossofcoolantaccident(LOCA)oramainsteamlinebreak(MSLB)accidentinsidecontainmentwherecontainmentpressurerisesabove2.9psig.Theprimaryfunctionsofthesysteminclude:1)limitingthepeakpressureinsidethecontainmenttobelowthecontainmentdesignpressureof12psig,and2)removalofradioactiveisotopesfromthecontainmentatmosphere.TheCTSsystemperformsthepost-accidentcontainmentdepressurizationandlong-termcoolingfunctionfollowingaLOCAorMSLB,anditremovesfissionproductsfromthecontainmentatmospheretoreducetheradiologicalconsequencesofanaccident.TheCTSsystem,consistingoftwo100%capacity,independentflowtrains,isinitiatedonlyduringanaccidentanddeliverschemically-treatedwatertothesprayringheadersinbothloweranduppercontainment.Figures3.2-3,3.24,and3.2-5showsimpliTiedflowdiagramsoftheCTSsystemduringstandbyconditions,theinjectionphaseandtherecirculationphase,respectively.Eachtrainofthecontainmentspraysystemconsistsofacontainmentspraypump,acontainmentsprayheatexchanger,valves,piping,sprayheadersinboththeupperandlowercontainmentvolumes,andallnecessarycontrolsandinstrumentation.Thesinglerefuelingwaterstoragetank(RWST)andsprayadditivetankservethetwotrains.TheoperationoftheCTSsystemconsistsoftwosequentialmodes,theirjectionphaseandtherecirculationphase.Duringtheinjectionphase,aportionoftheRWSTissprayedintothecontainmentatmosphereviatheCTSpumps.Bymeansofaneductor,theNaOHsolutioninthesprayadditivetankismixedwiththespray.Therecirculationphasebeginsafterthepumpsuctionhasbeenswitchedovermanually,bythecontrolroomoperator,tothecontainmentrecirculationsump.Waterisrecirculatedfromthecontainmentsumpthroughacontainmentsprayheatexchangerandbacktotheringheaders.TherearetwofaulttreesassociatedwiththeCTSsystem.Eachmodelrepresentstheunavailabilityofthissystemasitrespondstoaccidentevents.CSI-Thissystemmodel(faulttree)definestheresponseoftheCTSsystemtoprovidecoolantfromtheRWSTtotheupperandlowerCTSringheaders.Thismodelisalsoreferredtoasthe"injectionmodel".CSR-ThissystemmodeldefinestheresponseoftheCTSsystemtorecirculatecoolantfromthecontainmentrecirculationsumpthroughtheCTSheatexchangersandtheupperandlowerCTSringheaders.Thismodelisalsoreferredtoasthe"recirculationmodel."3-73 10AIIOSIKACSV.NIt0IK0)IIIK~IACIOIKACICNCOIINwCNI]CCNINIACIKIIIIIICI'I')IVCIII)OAIClskcvHIIIIIIIIIIC~II)kICll.kCC-.,~-t-LHLOCf)klvKC<.CC.0CfsktvCllKIVIfCNtltOo-tnS.0CllklvVIO.IllVtO.)hINNIACNIfUCL)ifL.CClsItXNCLOCII'KKKC1.0CI1'klCCf5klCOCNtlfS.0C15kKVKN)0ClsIt1VNCNICNAACCEIPALIKAKAICAIC~CISNSV1.0Cll.fftvIAO'tff~ICI'INlvLC.CIS-OOVCII~411~I\C.CI5IILCllIISCCK.ltICIAOlk~llttKCCliNXSASA~A))iflVCIAAVI~~ASOClsNLL.CIN).lf~Cf1I)IVOO.)tsL,C~ACCI).l)SV~45,CIS'1)ICCIII)ACINN)lsRVSTCI5Nt'10VCS'IOOfcfO10CASIOOILNf10SAfCIIVffCCftNANNA~CIVCLOOVAICAACILNN10CKICCKfCOACCOO,HOI~Ilcv10ACCVCLIVSVAICAALAlfICAIONAINAIAONAC1IAOA.~IIOI~tcfctCKCISCCSCAIKSIKSCVILVC1AsLOCAC~CLOKOACICAOCCSAOXSIOC~AACICACKCISKICAIKSIKICVILVCSAsICALCSCOINKflACKCSACLIIKAAILOCKSCVCNfcfCICNCCSIAVNCSOfISMII~COl.sl~I11COISlc).)OOAl$41ISCtI.SO).ltOAl"101lsICSVIAOIC5VNICNAACCsctfcfKANAKAKO10155LVALVC4)IAIO)vKfOAICNI~II0~LOCAI~CPCNLAL.C~LOCAC~CLOICOClS.0~stALC~IVCNCCOVISAAIACIVAIC~IIAKAO3-74Figure3.2-3ContainmentSpraySystemSimpliTiedFlowDiagram-StandbyConditions 0)0)e SVIll10AIN)ltKac~aIIICOIIIIX~IacloatcaCIOIC(NIalmaf[mlal>>CAS(IS~ItlvK.CI0\0cll.rttvCl\atlv50Vt0.111VIDIISCll'll\VC15ItlVIC5Vfl(NCSV0l(aaaa(cIattarKANAKaNaft01SrfrlIVCL~IICISItxLOCll.ltlCALC.5050CISsttcCllItKVID')0VID)I)CIS1)XIIII1ICISINVICllINVIClc~Itsv-,.aHHIIIIIIIIIICf5INCiCll0(CICIS.I)SC-...+9HOD'tllCISIllVaa5,0CISIIIV~CIttt'ICtl~I~)vLCCIS.NSVttSVCI5.1IXI.0L.CC15~ItaCIS.INCCISItXOD.tltCll~NxStaarASDIIIVCIAANI~)a~~'14Cll~IISI@I.)I~51IN51NlAa5.Clll)SV~al.C15S)XCl1INCIN)tflCllIllvADtt)RMSTLCCll~Nl10VC)f10Call10Sat(frtaa((la)aNW~CfVCLlaDVAISSA(I(IN10CKACCKrCOACCCILADSall(v10CvatctacIaav)loa(fvcLDDvalettvavl(AICNtataftDaac(la(LLAIIDI~OCICSCKC11C(5C~IXSIK5CVXVCSA5Locacl005(Dacfcl0ccsaNcs101,~vt(fca(KCDaua:ICIDCICvaLVCIAlslaacsct(aaact(a(K()AaD(cllIKAalLOCACS(t(0XICXKCNAVNCSOt.51al.llOttSNIIl(Ã..Na)SO(Ã".SI~)11W..SO).ta.III).CSIClvfaDIc5vNsowlcc5lttcrKANAKANS101(SLVALVCIDIAIIONXfOOIONS~IC.0LOCtf~Ct(V~II0~LO(al~CLOS(~(I5.0~5(ac(~It(v3-75Figure3.MContainmentSpraySystemSimplifiedFlowDiagram-IqjectionPhase 5V101IOAIK)SIKt(KIOXaOOSc~Ia(IOAKACIOIC(NIAINCNII07IIAOACAIIIIIII5DCIS.VSV~5.0CllsCOVO0'tt(Staa~ASIIIIVCIN~a~alaCX114I@I(ItINItl~SII~IRMSTIr.Sl(IIIXVCIIISSV(15Illvu.CIultllIIClsIt(V-m-IHIIIIIIIIIICIIIo(IcltlorICn0(C-~-HHCISIll(l.0(150(Vl.aCIS.ltIVIaC'llXIV(15~ItSV(5V(AOICSV~1saaaa(CSvtt(IKAXAKAX~(AOIst(rl(VCLtllCltkXu.cCllXICALCt0(15IC(CCaClsIM~ClsQKVI0litVI0illVI0lllVAOIhlutthC\I'I~IvL.0(Is-rhv4CCI5.IL(C'llIIXChNXCISIIXClsIIXCI5~IltvOO.((SCI5.III(IKStls5(~IttL.C(15IIO10V(tt00t(tt~asCI5IISV~as,ClsISX10CAtlttatiaaKNIO(V(IIwJ((IIOItvattf(ICLIKAVaI(~atI(OS10CKKCNCTCOICClr(IM'IIICNlaSIVA(SICt5NAS10ACfvCLINSval(~tINVKAIIOItlat'CIICIAaIIOI~A(((t(K(IS(C5(IIIC5IKSCVKVCSA5Lo(a(~cla5(aao(10c(saIcc'I10'I.~aatrcttK(h(cxhlclIKlcvuvcsasltaLtt(thaAO(t(K(saADKL(IKAalLOO(~It(N~(s(xK(IAAvlacsOtISII~11Ott.sl~~.IS(7"I.SIII10DttSl~)11(7"ISIISttO't.llhISIcsvttortsv~11(NAI(C5(tt(lKA(CAICAXt00(S1.VILVCIOIAIIOIX(INIICNS~II0~LD(atl(t(N~IIC~LO(atl(LO'XO00a~5(uC~OCN3-76Figure3.2-5ContainmentSpraySystemSimpliTiedFlowDiagram-RecirculationPhase 32.19ComponentCoolingWaterSystemTheprimaryfunctionsofthecomponentcoolingwater(CCW)systemareto:a)removeresidualandsensibleheatfromthereactorcoolantsystem(RCS)viatheresidualheatremoval(RHR)systemduringplantshutdownb)coolthespentfuelpoolwaterandtheletdownflowtothechemicalandvolumecontrolsystem(CVCS)duringpoweroperationc)providecoolingtodissipatewasteheatfromvariousprimaryplantcomponentsd)providecoolingforsafeguardsequipmentTheCCWsystemisasupportsystemthatprovidesanintermediateloopbetweentheRCSorotherpotentiallyradioactiveheatsourcesandthelakewater(essentialservicewater)toensurethatthecomponentsreceivingcoolingwaterdonotleakradioactivefluidoutsidetheplant.TheCCWsystemalsoprovidescoolingforeachoftwosafeguardheadersfollowingasafetyirjectionsignal.Figure3.24showsasimplifiedflowdiagramoftheCCWsystemforCookNuclearPlantUnit1.TheCCWsystemisaclosedcoolingwaterloopconsistingoftwocomponentcoolingwaterpumps,twocomponentcoolingwaterheatexchangers,asurgetank,achemicaladditiontankandassociatedpiping,valves,instrumentation,andtheequipmentbeingcooled.Aninstalledsparemaintenancepumpisavailableasareplacementforeitherunit'sCCWsystem.Thispumpisplacedinservicebyrealigningitsassociatedvalvesandbyswitchingthepumpintotheoutwf-servicepumpspowersupplyandcontrolcircuitry.ComponentcoolingwaterisnormallycirculatedbyoneofthetwoCCWpumpsthroughtheshellsideofoneofthetwoheatexchangers.HeatisremovedfromtheCCWsystembytheessentialservicewaterwhichflowsthroughthetubesoftheheatexchanger.Componentcoolingwaterissuppliedtothreeheadersofservice:1)Thewestsafeguardsheader2)Theeastsafeguardsheader3)ThemiscellaneousservicesheaderTheCCWsurgetankisconnectedtothesuctionsideofthepumpsandaccommodatesthechangeinvolumeduetothermalexpansionandcontraction.Bymonitoringthesurgetanklevel,leakageintoandoutofthesystemcanbedetected.Make-uptothesystemissuppliedtothesurgetankfromthedemineralizedwatersystem.TheCCWsystemchemistryiscontrolledbychemicaladditiontothesurgetankthroughitsownchargingsystemand,ifrequired,bysystemblowdown.Chemicalcontrollimitsarespecifiedinplantprocedures.TheCCWsystemisasupportsystemtotheengineeredsafeguardssystemandisrequiredforpost-accidentremovalofdecayheatfromthereactor.Twocompletelyindependent,parallelheadersareavailableforheatremovalofthesafeguardsequipment.Theinstalledsparemaintenancepumpiscapableofcompletelyreplacing,bothmechanicallyandelectrically,anyoftheotherpumpsoneitherUnit1orUnit2.Thetwoheadersarenormallycross-tiedthroughthemiscellaneousservicesheader,butafteranaccidentoccurs,theheadersareseparatedbytheoperatorandfunctionasindependentsystems.PowerforeachCCWpumpisprovidedfromaseparateelectricalbus.Themotorwperatedvalvesassociatedwithagivenpumpssafeguardsheader,includingitssupplytothemiscellaneousservicesheader,areprovidedbythesamebus.Eachbusisfedfrombothnormalandemergencydieselgeneratorpowersources.Thepowersuppliesarearrangedsothatonepumpanditsassociatedmotorwperatedvalvesareservedbyeachemergencydieselgenerator.3-77 TheCCWsystemisrequiredtobeinserviceatalltimes.Duringnormalpoweroperation,oneheaderofCCWisutilized.Thesecondpumpisonstand-byandwillstartautomaticallyuponalowdischargepressurefromthein~icepumporasafetyirjectionsignal.TheCCWheatexchangeroutletvalveinthestand-byheaderisnormallyclosed.Bothsupplyvalvestothemiscellaneousservicesheaderarenormallyopen.Thisalignmentprovidesforacoolingwatersupplytobothsafeguardsheadersandasupplyofcoolingwatertoallthemiscellaneousservicesheaderequipment.Thereisnoneedtomanuallyrealignthesystemshouldthestand-bypumpberequiredtostart.Whenasafetyinjectionsignalisgenerated,thestandbyCCWpumpreceivesastartsignal,theESWreturnvalvesfromtheCCWheatexchangers(WMO-733,737)receiveasignaltogotoapre-setposition,andtheCCWheatexchangerdischargevalveinthestandbyheaderreceivesanopensignal.UponswitchoveroftheECCStocoldlegrecirculationfollowingaLOCA,theCCWdischargecrosstievalves(CMO412,C14)aredosedtoisolatethetwoCCWheaders.Thispreventsthefailureofoneheaderfromfailingtheotherheaderanditalsoallowsthebalancingofheatloads.TheclosureofthesevalvesalsoisolatesanyradioactivecontaminationoftheCCWsystem.IsolationofthetwoheadersdoesnotaffectCCWoperation.UponatotallossofACpower(stationblackout),thenormallyrunningCCWpumpstopsoperatingduetoalossofmotivepower.WhenACpowerisrecovered(eitherfromloadingthedieselgeneratorsorrecoveryofoffsitepower),theCCWpump(s)automaticallyrestart.(Ifthepumpswitchisinthepull-to-lockposition,thepumpswillbemanuallyrestarted.)Duringcooldownofthereactorcoolantsystem,twoCCWpumpsandtwoCCWheatexchangersareused.Ifapumpfailsundertheseconditions,thecooldownratemaybeslowedorevenstoppedforthetimeperiodrequiredtoalignthesparepumpforservice.Duringcoldshutdown,twoCCWpumpsandtwoCCWheatexchangersareused.Itshouldbenotedthatthespentfuelpitheatexchangercanberemovedfromserviceperiodicallyorservedbytheotherunit,thereforeenablingasingleCCWpumpandheatexchangertosufficientlyhandletheheatloadfortheshutdownunit.3Therearefourmodels(faulttrees)associatedwiththeCCWsystem.EachmodelrepresentstheunavailabilityofasingleCCWheaderfortwodifferentplantconditions.Themodelsaredesignatedasfollows:CCWE-ThissystemmodeldefinestheunavailabilityoftheCCWeastheadertoprovidesufficientflowtotheeastRHRheatexchangerandotheressentialloadstomitigatetheeffectsofaLOCA(bothduringinjectionandrecirculation).ThisisfornormalACpowerconditions.CCWW-ThissystemmodeldefinestheunavailabilityoftheCCWwestheadertoprovidesufficientflowtothewestRHRheatexchangerandotheressentialloadstomitigatetheeffectsofaLOCA(bothduringirjectionandrecirculation).ThisisfornormalACpowerconditions.CCWEL-ThissystemmodeldeflnestheunavailabilityoftheCCWeastheadertoprovidesufficientflowtotheeastRHRheatexchangerandotheressentialloadsafterACpowerisrecoveredfollowingastationblackout.CCWWL-ThissystemmodeldefinestheunavailabilityoftheCCWwestheadertoprovidesufficientflowtothewestRHRheatexchangerandotheressentialloadsafterACpowerisrecoveredfollowingastationblackout.0'-78

~5'SlIIUISOIVtlIC(t'v'tftOLCKLC~~KOl5(ILVfKLIIO4LCOL(I5f4'5'lCCIL(t~C(4ICKVlOtf'VKCV'IIKVIClif'VKCKICKvf(CVIn(CVKI~tI~ffLf(itKC'llCCY.II~~IOfINIII(CvtffCCVillCCVlitCCVIIIIVOIffIS(5UYfOISSItOIC5VVIIVCCVIICVOOIi~(CVIIVOO'IIS5ICISCOO+lOCCVIIKCCV-If(CCV-iii(~tVCCCYIIKCKI~IIIIOIVlIIIIfLKffifKLKtC(t'5'CCMfoalCC(L(t~KOIKflVIKftSOOLCOL(IIVVf-4LOCL(4KOIICKIOOOt'5'COlK&IOCl~'COIf5&VIIOCfvOO.~IfCICI~ISISOICSVifif(Clfiv(OISIfkj(tKievCCvtNIOICILVKVCfOIIIIOIICIOCIRLS~IfC~IfkfCCIICIt5IOVOCNIICfvl'IC~IfIfu(I~IVJCCIIOISIOVL45~COVOCVIurOIIIIIi4COii4KVIIIILfnoiIIOULKf(KYCCKIYIYCO&IOSSIfSttSISSIfCtIS'lifttfO"tSISSLI~CtI.SIISIItIttSIIIIIICtI5iilttO'MSiiftfFigure3.2-6ComponentCoolingWaterSystemSimpliTiedFlowDiagram 32.1.4EssentialServiceWaterSystemTheessentialservicewater(ESW)systemprovidesthecoolingwaterrequirementsforthecomponentcoolingwater(CCW)heatexchangers,theemergencydieselgeneratorcoolers,thecontainmentspray(CTS)heatexchangers,andthecontrolroomairconditioningcondensersandairhandlingunits.Italsoprovidesanemergencysupplyofwatertotheauxiliaryfeedpumpsintheeventthatthecondensatestoragetanksareemptiedorotherwiselostasasourceofwater.TheESWsystem,sharedbybothunits,consistsoffourESWpumps,eachwithanautomaticbackwashingduplexstrainerandassociatedpiping,valves,andinstrumentation.Thesystemiscomprisedoftwoidenticalmainheaders.Eachheaderisservedbytwopumpsandeachheader,inturn,serveshalfofthesystemloadineachunit.Thetwoheadersarearrangedsuchthataruptureineitherheaderwillnotjeopardizethesafetyfunctionsofthesystem.TwopumpsaresuHicienttosupplyallservicewaterrequirementsforunitoperation,shutdown,refueling,orpost-accidentoperation,indudingalosswfwoolantaccident(LOCA)ononeunitandasimultaneoushotshutdownintheother.However,athirdpumpisnormallystartedundertheshutdownandrefuelingoperations.Allpumpsreceiveastartsignal(Sl)intheeventofanaccident.Figure3.2-7isasimplifiedflowdiagramforESWforUnit1showingcross-tiestoUnit2.Duringnormaloperation,waterissuppliedfromthelake,throughthecirculatingwaterintakepipestotheESWpumpssuctionwelllocatedinthescreenhouse.Analternatewatersupplyisavailablebyopeningtheslidegates(WMO-17and-27)betweeneitherdischargetunnelvaultandtheforebay,ensuringawatersupplyintheeventthattheintakesareunavailable.Duringstart-up,normalsystemoperationorshutdown,ESWissuppliedtotheCCWheatexchangersandthecontrolroomairconditioningcondensers.Theremainingheatexchangersaresuppliedduringalossofoffsitepower(LOOP)and/orasafetyinjection(Sl).SincetheESWsystemisrelieduponbysuchengineeredsafeguardssystemsasthecontainmentsprayandemergencycorecoolingsystems,itisdesignedasaSeismicClassIsystemwiththeredundancyandothercriteriaassociatedwithsafeguardssystems.Therearefourmodels(faulttrees)associatedwiththeESWsystem.Eachofthesemodelsrepresenttheunavailabilityofthissysteminresponsetodifferentaccidentevents.ThisfaulttreemodelstheUnit1(U-1)westheader.Ifutilizingthewestheader(standbyheader),theU-2eastpumpwouldhavetoremainon-linetosupplytheU-2ESWneedsandpreventanyflowdiversionfromU-1toU-2whiletheU-1westpumpsuppliesU-I.Thecrossconnectvalvesarenotmodeledsincefailurewouldaddsuccesstoanyfiowdiversion.ESWEThisfaulttreemodelstheUnit1eastheader.WiththeU-1eastpumptrainsupplyingflowtotheeastU-1header,eithertheU-2westpumptrainwouldhavetopickuptheU-1ESWloadsafteritstartedonthesafetyinjectionsignal(iftheU-1eastpumptrainFails)ornootherflowdiversioncanbeallowed(thisflowdiversionismodeledintheformofvalvesinadvertentlyopening).WiththeU-2westheaderinastandbystate,noESWloadsfromU-2wouldbeplaceduponit.Thus,theU-2westpumptraincanprovidefullflowtotheU-1eastheader(barringanyofthementionedflowdiversions).Thecrossconnectvalves(WMO-706and-707)aremodeledsincetheirfailurepreventsU-2flowfromgoingtoU-1.ESWWL-ThisfaulttreemodelstheU-1westheaderinresponsetoalossofpowerevent.ThelossofpowereventisassumedtoaffectbothUnits.ThiscaseismodeledthesameasintheESWWmodelexceptnowallpumpsmustberestarted(andchecksvalvesopened)insteadofthestandbypumpstartingasbefore.Fortheformerlyoperatingpump,thedischarge'\3-80 motoroperatedvalvedoesnotdoseonalossofpowerandthusdoesnothavetoreopenwhenthepumprestarts.ESWEL-ThisfaulttreemodelstheU-1eastheaderinresponsetoalossofpowerevent.AsintheESWWLmodel,thelossofpoweraffectsbothunits.Also,thetreatmentofpumpsandvalvesisthesameasintheESWWLmodel.341 VIO.11105atDCNICTSLINDVAICAKAICIONNGCNKISV10IIAIVFINtCSV-NlvIISIIVav111I~Ill.~@VIVlllSSTIOIANNalak04IMIfoANNAKLSatIMIWO.lttONCSIVVIVTIt1105'TATCNI.TN-TV4VIV-tttL.0CSVl115CDITITLIDOIACCOITCN550KalCIONNCCNc5v1015Clv.II~IWOlta105IAIIOIDaataaftt.lISIIVIV1~fNOI5DCINICktI510SCKCta55VICWCTillI4ClvIltavCSV110C5VISINCICL'AI'ACNCIvallaCDACNIKTCL'AI'VKDLCOQAACDIIADtcNTStaa1KAICIONNDCNwO115K¹IVDICSCLarAlaCODI.CDIC5CL'ATVavltlAllCTXLCIICTIL'CD'NV111AlaCOD.CNV.tCaa~WD-ttlC5VINClvIltt-WO-TISCKSV-litttOCSICvavtas'IOIIATttlTNADaNCIta1C'Ovav-ttsloSlatlolcaalaacctNOISCKCIACTUTCIf111I@VIV-IIIICICLCD'aCNCTL0VAICACDLCNCSVLSt'CTIOTCLCD'AC~ON.CTCLCNIICICL'CI'avttsAltCCXLCClvIISVID.111VIO115IIOIafaNANDINOLMICDTDCNICDLINOVATCAKAICIONNCCNNCISCVIO11110aNWAILDalLNIITONDafvtvaa5wft101Ctv-INCDCSICVNVtll105tAIKHTNADNCt~Dvav-Ill1111CI0C.I10COIT10.KOIACCINTCNTINKAICICNANGCNC5V.IITN10STAIIWINAIAACCtIISIIfNOIICK5NATVT5CDIIADKNI511ATVIO115NCAICIOWCCNwctmKNCU-tVtalIwNlaatClvIafvt1lilt@VNVt-OCSIVRV151IO5IAINTI~NaaaaattfVAV.TTIt-tt-tv'IO51AITOIDAAINACCTAOITCPCCtaatNICICTTCSl.VAI.VCHTIATIOIICTTAIIIOO'>La~LOCACDDINLSTIAIKNIacavaTNvaavclIvlvlfaLCLOIC~INDI5055DtAIAOltOVCA.VCNIvaavftlfCACNCCMawNCD01ISIIStlOatSlitCS3-82Figure3.2-7EssentialServiceWaterSystemSimpliTiedFlowDiagram 32.1.5NonessentialServiceWaterSystemTheNonessentialServiceWater(NESW)Systemisasharedsystemwhichprovideslakewaterforcoolingandmakeupwatertonumerousplantsystemsandcomponents,indudingupperandlowercontainmentventilationunitsandtheplantandcontrolaircompressors.ThesystemconsistsoffourNESWsupplypumps,eachwithanautomaticbackwashingduplexstrainer.Duringnormaltwounitfullpoweroperation,theNESWsystemissharedbetweenUnit1andUnit2withthreeoffourNESWpumpsneededtosupplyrequiredflow.Thefourthpumpandstrainercombinationisprovidedforstandbyserviceasaninstalledspare.TwoNESWpumpsarelocatedineachunit.Eachpumpnormallytakessuctionfromitsrespectiveunit'scirculatingwaterintaketunnel.Ifthesourceofwatertothecirculatingwaterintakeisinterrupted,allfourNESWpumpsarecapableoftakingsuctionfromtheirrespectivecirculatingwaterdischargetunneland,bymeansofacross-tieline,eachcanalsotakesuctionfromtheotherunitscirculatingwaterintakeordischargetunnel.Thus,nonessentialservicewatersupplytobothunitsisassured,evenifthetunnelsofoneunitareoutofservice.ThereturnwaterflowstothecirculatingwaterdischargetunnelwhichdischargesintoLakeMichigan.Figure3.2-8isasimplifiedflowdiagramoftheNESWsystemduringnormaloperatingconditions.Figure3.2-9isasimplifiedflowdiagramoftheNESWsystemduringstationblackoutconditions.Therearetwomodels(faulttrees)associatedwiththeNESWsystem.Eachmodelrepresentstheunavailabilityofthissysteminresponsetodifferentaccidentevents.NESW1-ThissystemmodeldefinestheresponseoftheNESWsystemfollowingthereceiptofasafetyirjectionsignal.NESW2ThissystemmodeldefinestheresponseoftheNESWsystemfollowingastationblackout(SBO).Forthestationblackoutcase,onlyUnit1isassumedtobeundergoingthestationblackout(thusthedieselgeneratorsinUnit2comeon-line.)3-83 INTVKITNKV+IK'10ADOSAHDC10CDIfANACNIVtNIIIATCHVNISTVCVr10AkCDTVC5SCN510AllCDNACSTOATNSV141TOCCHIANACNIVCNIIIAINN44415tvrlvAINKTV4kN10ADDSTKIC'10SfCANCCKAAITO~IDrDQINfLAIHIHH4NCINSVITCHI~-WSSINSVNOIIKINHSH10O'INCAIHIII1041510OIKAVIIItLOIlttVIO411CATVHWNSVIIOItWWtvkvIkvkvOvNNIVKI41110SI'IDNACC~IAACLIVtV510IVOVIVNf1DIIHSC15t10NAACHNVlltt$15101ACIDIINHTAHIHrtCKHICALCLCANINSICINOSTATTDIIOCLTCILDKLCAfkfkt5tNSV1110fATHCHSC15$CVtvSI~tHOV144NCITDNACC1VIO4410044$ItNSV10ItHOVIIS10ATKOTICACIOAflOSTKACIHHVHtlSHISV4lttINSVKIISSSTHIIVHffIKNOSItHIIVXl10CHC~AOICCICII~$04045f4AVItvkvIll'10TCAINO~OCCA~LOVNNINfHHt101tvlSVIkttHOV&41MSV101$HOV&lf5tNfvllt5-IIvvv'IkI.NtV114$10SIIDNAICIDACLIK5V141$fADIIHNCSSNtVAVSIAtNIVIlkfADItHNCSSHtVAVIktvrfvll45IOTITDNKCIVTCL~ISDNACCIVIACLI.VIO14~tVIO144SIIONA'144CL10KCHHOIOVkHANITIAC14AN~KftlCICCITCIIPIICIIKICVKVC'IAiNrlfftfLIVHVCTMIC/CACKCSAOCCS>OlKfCKKCWlvlr05DI'504IDlttCNt504ttLI~fktklvATC~~IAINISHIAl4SrftlfSIXCIIONSKHALIPt.$044I~Figure3.24NonessentialServiceWaterSystemSimplifiedFlowDiagram-NormalOperatingConditionsIOHKHCCINIOfllCf4AV I~sslvKItNNivCsts10AIIC)5tKK10COSIANACNIVCNIILAICSSINII5IVsSV10AkCOft(550A510COslANKNIVtNIILAIIOSStilllssSVIll10AllCOAN(55015tvsSvtitsvslvSANIOAISC)SIKt(IOi)CANCCKNAIOIttOVNPASSCLASNIAINLOCS.NSV.IKNISK5V~SISNINSVlOON10DIKCINI~ILdsll10Ols(tINI~1IdslltVSONltVsSVIIVI~NSVIlies)(ttt'WtvsSVktNkvsSVNNfD~I'IONA(CISAAC(IVAVSttI.NSVISINfAOIIM55510NAKNA'AICN51'IIDStCICNIIOIIANIANSCKIIKALCLCSNNdICltd5IAICSSkNSVIII10CLICtLCHLL(t~A(ls((5ItNsSV.ll'ItVSVStt'~kiCSOCt.NIVIIINfAOStvts(SSIISPICLtVIO.SSSIVIAlt15IACL10*INOSPKACIWIVASCIINSVKSISINNCSSSIVssd114ICNsSV15110fk(ttds(CINSIt(tiQssOILATS/ItvsivNtION(AIIKKill(~EOVNV>>IANI10AI1051SCACt-NSVKss~NSV~ItitvtdSSSIss5VNtiIVNVSkI.NSV1145I~Nkl1INSSVfll5jVSO.SSk)oIVAV114I.Nlv.klltvsSVHtloctvtvlsltss5vH15VISvllll)tVtvlit1Nlv.illltNSVIICS10~1$(~islsf\IVnIN)4.)W10IIv-wIIIKNsssc4OClttstt~IIOIAA(CIIAACLIIIOIAICCIISssKLISNVSIIVs(NSII10INDINOLOVKsssvIfk(tttst5~KIClfKCIKlttlKS'IKICVIIV(5A50111(tftfVSNVt5NSIICICA(KCSACCCSSdlt(fCACSCCIAAVIKS'tISls~~IttC.SNItt(NISSISA.IAIN'f'ISSSAI~ldl(5I5~IIH'IWI(tlsASSI5lstSK(lIO>>SldsSLFigure3.2-9NonessentialServiceWaterSystemSimplifiedFlowDiagram-StationBlackoutIOIKN(CNANSfit(AVsst3-85 g)r'i 32.1.6CompressedAir(ConholAir)SystemThecontrolairsystem,whichisapartofthecompressedairsystem(CAS)providesfilteredanddriedairforinstrumentandcontrolusageintheplant(bothinsideandoutsideofcontainment).CompressedairissuppliedtoUnits1and2throughanairdistributionsystemlocatedintheturbine,'uxiliaryandcontainmentbuildings.Thisdistributionsystemconsistsofasharedplantairringheaderextendingthroughouttheturbinebuilding,apairofparallelplantairheadersintheauxiliarybuilding,andaplantcontrolairheaderineachcontainment.TheCAShastwoPlantAirCompressors(PACs),eachofwhichiscapableofsupplyingthetotalcompressedairdemandforbothunits.OnePAC,plantairreceiver,andplantairaftercoolerislocatedineachunit.Eachplantairreceiversuppliesitsownplantairheaderintheauxiliarybuilding,however,thesharedturbinebuildingplantairheadermaybesuppliedfromeitherplantairreceiver.Additionally,eachunithasacontrolaircompressor(CAC),whichiscapableofsupplyingthatunitscontrolair(instrumentair)needs.DuringnormalCASoperation,onlyonePACisoperatingandsuppliesit'scompressedairtotheturbinebuildingringheaderandtoitsownplantairheaderintheauxiliarybuilding.'heturbinebuildingringheader,inturn,suppliescompressedairtothestandbyplantairheaderintheauxiliarybuilding.Sincethesedistributionheadersareparallelandhavehoseconnectionsinessentiallythesamelocation,oneunit'sheadermaybeisolatedfromtheCASwithoutaffectingtheavailabilityofplantairtotheauxiliarybuilding.Compressedairisthendeliveredtotheheaderbranchesthatfeedtheservicesrequiringcompressedair(e.g.,screenhouse,service,turbineandauxiliarybuildings).Compressedairfromtheturbineroomplantairheaderisfilteredanddriedforinstrumentandcontrolusage(controlairsystem).Eachunithasitsownwetcontrolairreceiver.Ifthereisaunitinstrumentandcontrolairdemandandbothplantaircompressorsareunavailableforservice,lowairpressureateachunit'swetcontrolairreceiverwillautomaticallystartbothCACs.TheCACswillrunonconstantspeedregulationuntilstoppedbytheoperator.Compressedairtobeusedforcontrol,instrumentation,containmentintegratedleakratetesting,orcontainmentpenetrationandweldchannelpressurizationisdriedtoadewpointbelowtheminimumtemperatureexpectedatitspointofuse.Eachdryerhasaprefilterandafterfilter.Theprefilterpreventscontaminationofthedryerdesiccantfrommoisturecarryoverorscale.TheafterfilterprotectstheCASdownstreamofthedryersfromdesiccantdusting.Theuseofcopperandstainlesssteelforcontrolairpipingminimizespipescalecarryovertoinstrumentsandcontrols.Eachunithasaredundantstringofcontrolairprefilters,dryers,afterfiltersanddrycontrolairreceiverslocateddownstreamofthewetcontrolairreceiver.Figure3.2-10isthesimplifiedflowdiagramoftheCAS.Therearetenmodels(faulttrees)associatedwiththecompressedairsystem.Eachmodelrepresentstheunavailabilityofthecompressedairsystemorportionsofit.CONAIR1ThisfaulttreemodelstheUnit1PACoperatingandtheUnit2PACinstandby(readyforautomaticstart).BothPACsfeedintotheturbinebuildingplantairringheader,whichcanbeisolatedintosectionsbyvalvesPRV-10,-11(Unit1)andPRV-20,-21(Unit2).Thecompressedairthenfeedsthecontrolairdryerstringsforfilteringanddrying.Thismodelendsatthepointwheretheoutputofthedryertrainsmeet.CONAIRLS-ThisfaulttreecloselyresemblesthatofCONAIR1exceptthatthePACshavetostartandrunfollowingalossofpower.Also,valvesPRV-10,-11,-20and-21havetobereopenedsincethesevalvesdosewhendeenergized.CONAIR2-ThisfaulttreemodelscontrolairbeingsuppliedtotheheaderinsideofcontainmentthatsuppliescompressedairtothePressurizerPORVs.The346 airflowisthroughcontainmentisolationvalvesXCR-100,-101andpastregulatorXRV-186.FaulttreeCONAIR1iscalledinasasub-tree.~rCONAIR2LThisfaulttreecloselyresemblestheCONAIR2treeexceptthatvalvesXCR-100,-101havetobereopenedafteralossofpower(shutwhendeenergized).The,CONAIRLStree.iscalledinasasub-tree.NoIPEmodeledcomponentsexistdownstreamofvalves-XCR-102-103.<Thus,thesevalvesarenotmodeled.CONAIR3,CONAIR4andCONAIR5Thesefaulttreesmodelthepressurereductionof~100Ibcontrolair(tiedin.assub-tree(CONAIR1)to85lbair(CONAIR3),50Ibair(CONAIR4)and20Ibair(CONAIR5).Thepressurereducersand.filtersassociatedwitheachpatharemodeled.CONAIR3L,CONAIR4LandCONAIR5LThesefaulttreesarethesameastheoriginaltreesexceptthatCONAIRLSisnowcalledinasasub-treetoaccountforcontrolairresponsetoalossofpower.Oi0'47 PLANTANAPI'ASC~Ittt5Af)CCfSLICOSAlt)CIC)5<OC1111IKIETC)5<OAIII~5V15PL<<ITAN~CCCIVCCK-C)PAO.IVAV.TISTC)SOICAI)OICAlt<C4I)ICSV~K4IIVII<VI<<I(~<If~IIISAfICPCCCLCtI'OC'IIVSV<tlIVPVlitPP5.I~KSVCOIISOLAIS~C)LOCA5~CO<IASAC<O)ISIS<<5SCSIT)L)It)51CQNTRDLAIR5VCCIIVPAItlV.tCO<INLAltPAV10rc,OPSVt<PC.tlV15PL<<<5Alt~CCCIVCSK5$U-1PACtVIVSVIPI<V11It.SVI)lAPICSfLIOIS<OAtlANIATCAS<OKItllPPCITLICAS10<llPPSCo\<I~IISWANSVTCPCNLCAIWA-III11)SPIC<.l)15NTCO<I~ILANtCCCIV4CA11<VSVONtVCAIIIVC~CO<1~ILANACCCMA5V~~~<Il~tAVI11SC<KIV~VIVSIItVAVTttCAlllPP5.tU-2K4AfICSCNLCSAtfIACKCPA<VS<SOCVItSltlllOPISQIA$1OPI)ITICI~OPISll~~IK5VsCOCSLVALVCIOTAIONICfIKTIBrt~110~1AIL)IVC<<~)fCTAILSCLOSC~VIVTSSfo3-88KSVFigure3.2-10CompressedAirSystemSimpliTiedFlowDiagram(sheetj.of2)

~IIIKOtlillACACIAKACIOICOIIA00001COIIASACKI1000C'ltaltt00'tCZMAIIACAIAl~LOlllIIIIIIIIIIIIIIIIIIIIIIIIIKA'IISft.%CAIICC\0\~HtIK0LCC'IOCftICANOfC.OlIt~IAVtlCK-K.500LlIfAtttaIt'taItI00V'\I~CAKAa.0a.Il.SrAAV05NV'05IAOICOelAILAIA515ICA1110L~PACIIIACI~CICKKCOIAVSfI00ISltKI~O'SltllSiCICCS~VALVC00IAIIOItCCIAIICSOAlft.~fALSCLOIC0C.ICAACLlll105ll)00tflltt5AOISO50.KACCRFigUre3,2-10CompressedAirSystemSimplifiedHowDiagram(sheet2of2)3-89 32.1.7EmergencyCoreCoolingSystemAttheCookNuclearPlant,emergencycorecoolingwaterissuppliedbytheaccumulators,safetyinjectionpumps,centrifugalchargingpumps,andtheresidualheatremovalpumps.Forconvenience,thesystemdescriptionsandoperationshavebeenbrokendownintothefunctionsof:accumulators,lowheadsystemoperation,andhighheadsystemoperation.3.2.1.7.1AccumulatorsTheaccumulatortanksaredesignedtooperateinthecaseofalargesizebreakinthereactorcoolantsystemandtorapidlyinjecttheboratedwaterstoredinthetanksiftheRCSpressuredropsbelowthepressureintheaccumulator.Therearefouraccumulatorsperunit.Theaccumulatorsarepressurevesselsfilledwithboratedwaterandpressurizedwithnitrogengas.OneaccumulatorisattachedtoeachofthefourRCScoldlegs.Figure3.2-11showsthesimplifiedflowdiagramfortheaccumulatorsystem.TheaccumulatorsystemisevaluatedinthecontextofalargeandmediumLOCAwherethepressureintheRCSdecreasessufficientlytoallowrapidinjectionofcoolant.Sincetheaccumulatorsystemispassiveandnomanualactionsarerequired,irjectionoccurswhentheRCSpressuredropstoabout620psig.Whenthis,occurs,theboratedwaterfromeachaccumulatorflowsthroughitsrespectivenormallyopen,motorwperatedisolationvalveandcontinuesthroughitstwocheckvalvesintotheattachedRCScoldleg.Thereisonemodel(faulttree)associatedwiththeaccumulatorsystem.Thismodelrepresentstheunavailabilityofthissysteminresponsetodifferentaccidentevents.ACCThissystemmodeldefinestheunavailabilityoftheaccumulatorsystemtoinjectthecontentsofthreeaccumulatortanksintothethreeintactRCSlegsgiventhatalargeormediumLOCAhasoccurredonthefourthRCSloop.3-90

):

St166-3$1170L4REF.AErSCllVGNa.OP-5WSREV.20Figure3.2-11AccumulatorSystemSimpliTiedFlowDiagram00076:10.0812913-91 3.2.1.7.2ECCSLowHeadCoolingSystemOneofthefunctionsoftheResidualHeatRemoval(RHR)Systemistoprovidethelongtermpost-accidentcooldownrequirementsoftheEmergencyCoreCoolingSystem(ECCS).Inthisfunction,theRHRsubsystemoftheECCSprovidesalowpressure,highvolumetricflowratewatersourcetotheRCSbysupplyingwaterfromtheRefuelingWaterStorageTank(RWST)duringtheirjectionphaseandfromthecontainmentsumpduringtherecirculationphase.TheRHRsystemalsohasamajorfunctionduringnormalplantoperationsinthatthesystemremovesdecayheatfromtheRCSduringthesecondphaseofnormalplantcooldownwhenitisnolongerpracticaltocooltheRCStothecoldshutdownconditionbyuseofthesteamgenerators.ThedescriptionpresentedhereinislimitedtothatinwhichtheRHRsystemsupportsthepostaccidentcooldownrequirementsoftheECCSintheeventofaLOCA.TheRHRsystemisevaluatedinthecontextofalargebreakLOCA;however,thesystemisalsorequiredforrecirculationduringsmallandmediumbreakLOCAsforbothcoolingandflowtothesafetyinjection(Si)andchargingpumps(CC).TheRHRsystemconsistsoftwoidenticaltrainsperunit.EachtrainconsistsofanRHRheatexchanger,anRHRpump,valvesandassociatedpiping.AsimplifiedflowdiagramoftheRHRsystemfortheinjectionphaseofECCSoperationisshowninFigure3.2-12andasimplifiedflowdiagramoftheRHRsystemfortherecirculationphaseofECCSoperationisshowninFigure3.2-13.InperformingthepostaccidentlongtermcoolingfunctionoftheECCS,theRHRsystemhastwophasesofoperation:injectionandrecirculation.TheshutoffheadoftheRHRpumpsislessthan205psig.FollowingaLOCA,theRHRsystemissuppliedwithwaterfromtheRWSTduringtheinjectionphase.Duringtherecirculationphase,whichbeginsaftertheRWSTisdrained,theRHRpumpstakewaterfromthecontainmentsumpandiieetwaterdirectlyintotheRCScoldlegsifRCSpressureisbelowtheRHRpumpshutoffhead,andtheyalsoprovideadequatesuctionheadforthehighpressureSIpumpsandthecentrifugalchargingpumps.Inaddition,theRHRsystemprovidescooledwatertotheuppercontainmentRHRsprayheadersifcontainmentpressurerisesabove8psig.TherearetwofaulttreesassociatedwiththeRHRsystem.Eachmodelrepresentstheunavailabilityofthissystemasitrespondstoaccidentevents.LPIThissystemmodeldefinesthelogicassociatedwiththeresponseoftheRHRsystemtoprovidecoolantfromtheRWSTtotheRCScoldlegs.Thismodelisalsoreferredtoasthe"irjectionmodel."LPRThissystemmodeldefinesthelogicassociatedwiththeresponseoftheRHRsystemtotakecoolantfromthecontainmentsumpandinjectitintotheRCScoldlegs.Thismodelisreferredtoasthe"recirculationmodel."3-92

,)>k'I>'I'4L INSRE80TSIDE!CONTATNHEIIT'CONTAINMENTFROMSAFETYSI152MINJ.'N'I170L4SI161L4SVI04EIMO-312AVSTTK-33IMO390RHRPUMPHIN.FLOVLINESI148TOLOOPN4RCSCOlDLEGSI170L1SI161L1TOLOOPNiRCSCOLDLEGL.O.IPJI-316SI151EICH-311!!!FROM(SAFETYSI152SINJ.IIUMP'S'.O.IRV-310IHO"330TOCONTAINHENTSPRAYHEADERHE-17EL.O.RH116EIHO-340IHO-314TOCHARGINGPUHPSUCTIONCROSSTIELINEIMO-322RH113ERH108EIM0-310PP-35ERHRPUHPHINFLOVLINEFROHRECIRC.SUMPFROHRECIRC.SUMPSI170L3SI161L3TOLOOPN3RCSCOLDLEGSVI04VF.O.IHO-324HE-17VL.O.L.O.PP-35VSI170L2S1161L2IHO-326TOOOP021RCSCOLDLEGS1151VICH-321IRV-320IHO-331IMU-350RH116VRH113VRHIOBVIHO"320TOCONTAINMENTTOSAfETYINJ.SPRAYHEADERPUHPSUCTIONREF<DRAWINGOP1-5143"20Figure3.2-12LowHeadCoolingSystemSimpliFiedFlowDiagram-IrjectionPhaseECCSLH/RHR3-93 0;irwirP~~C1~I4'lCp-t0, TOLOOPN4RCSCOLDLEGSI170L4SI161L4IHSIDEOUTSIDEICONTAINMENTCONTAINHENTFR%ISAFETYSI152HINJPUMP'N'V104EF81IH0-312HE-17ELA1LORHRPUHPMIRFLOVLINETOLOOPNtRCSCOLDLEGS1170LIS1161LIIMO-316IRV-310IHO-330TOCONTAINMENTSPRAYHEADERRH116ERH113ERH108EIHQ-340IMO-314TOCHARGINGPUHPSUCTIONCROSSTKLINEPP-35ELORH104EFROHRVSTSI152SRDJINJ.SAFETYUHP'S'HO-322RHRPUHPHINFLOVLINETOLOOP03RCSCOLDLEGSI170L3S1161L3SI170L2SI161L2SVI04V!M.IRV-320IHO-326SI151VICH-321IMO-324HE-17VLllPP-35VRH116VRH113V'RH108VFROHRVSTTOLOOPI2RCSCOLDLEIH0-331IHO-350TOCONTAINMENTSPRAYHEADERTOSAFETYINJ,PUMPSUCTIONLlLRH104VRECIRC..SUHPICH"305'TK-84UREICH-306VALVEENCLOSURETK-85TOCONTAINHENTSPRAYSYSTEHREFTDRAVINGOP1-5143-20Figure3.2-13LowHeadCoolingSystemSimpliTiedFlowDiagram-RecirculationPhaseECCSLH/RHR3-94 3.2.1.7BECCSHighHeadCoolingSystemThehighheadECCSprovidesemergencycorecoolingandhelpstomaintainreactorcoolantinventoryintheeventofaLOCAoramainsteamlinebreak.ThemajorcomponentsofthehighheadECCSare:twocentrifugalcharging(CC)pumps,aboronirjectiontank(BIT),twosafetyirjection(Si)pumps,andtheirassociatedvalves.Theprimarysourceofwateristherefuelingwaterstoragetank(RWST)(irjectionphase);thesecondarysourceofwaterisfromthecontainmentsumpviatheRHRpumps(recirculationphase).ThehighheadECCSconsistsofthreeseparatesubsystems:onecontainingthechargingpumpsandtheBIT,onecontainingtheSIpumps,andthelastcontainingtheRHRpumpsandheatexchangers.Duringnormalplantoperation,acontinuousrequirementforfluidtothereactorcoolantpumpsealsrequiresthatonechargingpump,eithercentrifugalorpositivedisplacement,berunwheneverreactorcoolantpumpsareoperated.Duringnormaloperation,thesafetyinjectionpumpsandtheresidualheatremovalpumpsarenotoperating.AflowdiagramoftheECCSalignmentduringnormalplantoperationisillustratedinFigure3.2-14.ThehighheadECCShastwophasesofoperationfollowinganaccident:iqjectionandrecirculation.FollowingaLOCAorsteamlinebreakevent,thehighheadsystemissuppliedwithcoolantfromtheRWSTduringtheinjectionphase.ThisphaseendswhenthecontentsoftheRWSTarenearlydepleted.Intherecirculationphase,thewaterthatisspilledfromthebreakcollectsinthecontainmentsumpandflowsthroughmeshscreensintotherecirculationsump.TheCCandSIpumpsthentakesuctionfromtheRHRpumpsdischargewhichinturntakessuctionfromtherecirculationsump.Duringtherecirculationphase,boththeRHRandSIpumps'ischargelinecrosstievalvesareshut.Thisprovidestwoseparatetrainsintherecirculationphaseshouldapipeorpumpfailureoccur,whichisinkeepingwiththeplant'slicensingbasisthatpipebreaksmustbeconsideredasapossiblepassivefailureduringtherecirculationphase.TheconfigurationoftheECCSduringtheinjectionphaseisillustratedinFigure3.2-15andtherecirculationphaseisillustratedinFigure3.2-16.Therearefivemodels(faulttrees)associatedwiththehighheadECCSsystem.HPIThissystemmodeldefinestheunavailabilityoftheECCSsystemtoprovidesufficientflowtothreeoffourRCScoldlegs.(SIcrosstievalvesareopen.)ThissystemmodeldefinestheunavailabilityoftheECCSsystemtoprovidesufficientflowtooneofthreeintactcoldlegs.(SIcrosstievalvesaredosed.)ThissystemmodeldefinestheunavailabilityoftheECCSsystemtoprovidesufficientflowtooneoffourRCScoldlegs.ThissystemmodeldefinestheunavailabilityoftheECCSsystemtoprovidesufficientflowtofouroffourRCScoldlegs.HPRThissystemmodeldefinestheunavailabilityoftheECCSsystemtoprovidesufficientflowtooneofthreeintactRCScoldlegsduringrecirculation,3-95 Vl4JIJocagZNICL'VUpleroetNVl4JOIAZVtI-NzzzNNoKCaCJoIJUZZZZAzI-I-I-IZI-INl-VtII4-Wcacuoo333vZZZZZZZOI-tI-I-I-I-I-I3coccaUDv3ZzZZZZI-pI-I-I-HIZI-CCL'CDLlUzzzzzzzzzzI-VP&iI-I-I-I-t-mrnaCualeoerma0runeraerma0CuaterhemalITINruNIUNCUCUNPJPJPtPlPlPtPlPrPtPleeeeeeeeNIIIJI33uo33uccZZZZZZOZIt-I-pI-I-NI-000NPteIAeIAIAIAIAIAIAIECCOZZZI-I-tCtWoI-I-NI-H00NPIJAceo0IIKCL'CCJZzzzI-I-I-I-Ieulerm0Ioo33ZZzZI-00alulrrr3ccaCCuovZzzzzZI-tI-I-I-rmarrtrt0tI333ZzZIOCUtDIDCaIoo3ZzzI-I-I-NNIW3u'ZZI-VlICCZZZI-NNWWLlICJDCJCL'LzZZZZZZZZCOZIIVJI-It.0t-zzcupleIAtattD0Cha0ahaCICrOtheoIzz~kz~I-III-I-CUPJeIAo00ooNVJVJoVlm00rupte000ZZI-I-IcaCCZI-II-4.OZ0CuNoLJ333caZZZZZZI-I-ruprealeralNNCUruCUIIccLooD3ZZZzZZI-I-4pl-ICtchoCUPIOJCUPtPtPtPtIUUDZzzI-I-I-Vtal4-IJIoCCCCZZZZZI-VtAI-t-VlNIJoo3ZVlI-II33UD3ZZZZZI-I-I-elhercaooNpretaullictplplplptptplet~'0tt'eCL'UU3ZZzzzzzzzzzI-I-I-ttII-tNt-00CuPlrIA0IIDOrIAIAIAIAIAIAIAlflIAIAICLgCLOI-0cupt'Iaee'tauo333vo33ccca7coooZZZZZZZZZZZZZZZZI-NI-I-I-NpI-I-I-CIA'taItDO0CUPleIAulr00eeeeeerrrrtrrIrCc.IZZZI-0N0!cactIIOUZZ.I4.CCL'7.ZZZI4.WIoou333ov33ZZZXZZZZZIhoNPreDietIDIaa00OOChaCr0IJWK<<In3)lA4ICZWZ3U=NWl>-IINZW~UmzoziNWU<AW<4JCCIZIJO+N~v+KZZ<uc=zzAz<I-NBZ47,-Zewd4747~~zuwCaNcaxu'.mucON)UVCPINNQNN.'NarzJw-4ILJNCDA'-NNWD.W<a=NfCLCLCLCL-47Zz-zzz4lLAIDNwm=.z-IalaralaCouzzzzzzzzzz<zzWAG:mrarazCLCUCLNCL'CAzi-INt-Nt-+Nt-CLNONCaww4.IJUI-ocacrauwv333<2Zzz-ZzzzzONI-I-I-~I-I-IIIZ.CJClX4IA'oz4JZCJmG-JZzmalI-IJZOZza0fKI-IJCLIZZZVU4-4II-jI-I-OCIZCCa.LONO33WHUlytwwLJtJWAOZ<+wWz'ovari:Z>>>-I-<AW<P<VIzt-3Ny>>coccaozZN'CLCLWW<Aww~w-,3Jwtca2cuzLJNALI<3ZZVIAl-Iat-zwmu3z.,UZNXz<WuWACLWNIJIJZ>~-ZtJZZZ4CC4INC=~SwzNZWZNOQ<wt-&ZNZI-LNCN.O<<O<4INV-JWt-I-Zl-ILI-)N<xz3003caNzlazAzmwo<NLJ>>WAA>-CJW-Jcc<zwKiuvcavzozDSIAPERTURECARDZ3U44ZCOVJCLNIIJNCC<z4IIzwUcaUzcJzvCJ

DC&251Sndi5'1105MTnRVSTIHO-255I10-252LJL$1105$L.OS1100HRL04tlL.OS11055RCgHSS1111HSn04HSin0$$1111$S1205SV~II~maISnaisISKAPEM'~CARSIAtsoAva5hbleOnApertureCordiI~IllSndlt2SnTIL2I~25I~SORH115KIR%410IO&411TOlpgaSEALVATERHJKCCTCHN1TLTERSI&tQl5CS$0504k200QQ201CHARGOEIC$50SWTOIQCCIRV-252NV-251$1152IND41Sn452IQD480TQSKALVATER.SKATKXCHAHGERIH5-255ICH-250IRH$2!Slt4RRSCCA1$505K00-225IID@.251I~yISnA2LSsa<<aa!)Sn42L4DEC-04475-R9-91JAH5QEER>l.UNIT2ONLY.2~DENOTESHEATTRACING.3.VALVEENCLOSURE>TK-S4~ICM-305TK-85~ICM-306.4.INSIDEREACTORCONTAINMENT.5.LXL=LOCKEDOPEN.3-96Figure3.2-14KgbHeadCppljngSystemSimplifiedFlowDiagramNpmlalOperatingConditions92059503.3@-

pQ,(Qgr,~4%'l~~fCQ' I~$1ISIIMH$1$$$NIlJO-25$l4nE1SIltQS51111$IO$-255SI29$TTIRO'EAL.VATIRCJEETIQMFILTIRSIFRX$5RIIOM25)$542LlSIIIII~$0TIISEALVATERfEATEXOIANGKR~$$IOI-25$TDRESC/L%4$542L4IRKED1.UNIT2ONLY.2.-DENOTESHEATTRACDIO3LO.~LOCKEDOPEN4CLOSEDFORHP2ONLYVEC&4485-29-91JAH3-97Figure3.2-15HighHeadCoohngSystemSunphfiedHowDiagram-IqjectionPhasetr30soso'333-Q r't3~4bWyltpCOURQff,Q RYErr(22DO-241SKISI10SSSI111HSI111SH01E1HOIK1S1204ISEAWRYUREC~geeAvaHaMOOnk)~areCar~ISn4IL4SII20L4ItHI14KIQRCSC/L41IS04luaa4LI~lSQ4lll10&250SQ42LSSG4112ILCHI10IOk-24'IIIIK2IyISh42LSSh4ILSSQ4IL4VECW4495-29-91JAHKtIEZt.UNIT2ONLY.2.~DENOTESHEATTRACING.3VALVEENCLOSURElTK-84~ICM-305TK-85~ICM-306.4.INSIDEREACTORCONTAINMENT.S.LO.=LOCKEDOPEN,3-98Figure3.2-16HighHeadCoolingSystemSimplifiedFlowDiagram-RecirculationPhase9:soho.soss's-Q g~emF"sPl'~r)AC4>)jailIr47l 32.1.8EledricPowerSystanTheCookNuclearPlant'selectricalsystemsaredesignedtoensureacontinuoussupplyofelectricalpowertoallessentialplantequipmentduringnormaloperationandunderabnormalconditions.Theelectricpowersystem(EPS)ismadeupofthefollowingsystems:4160and600VAC,250VDC,and120VAC.Eachofthesesubsystemsaredescribedinthissection.3.2.1.8.14160VACSystanThe4160VACsystemindudesthe600VACpowersupply,offsitepower,andthedieselgeneratorsystems.Theprimaryfunctionsofthe4160VACelectricpowersystemareto:~Provideareliablesourceofmotivepowertoallelectricmotorsratedat400hporlarger.~Provideareliablesourceofelectricpowertothe600VACbusesviaa2000kVA,4160/480Vtransformerforessential(emergency)equipment,anda1500kVA,4160/600Vtransformerfornonessential600Vequipment.~Provideareliablesourceofelectricpowertothe480VACbusesviatwo1000kVA4160/600Vtransformers.Theprimaryfunctionsofthe600VACelectricpowersystemareto:~Provideareliablesourceofmotivepowertoelectricmotorsratedupto400hpindudingemergencyequipmentrequiredintheeventofafailureofnormalpowersupplies.~Provideabackuppowersourceforessentialinstrumentationandreactorprotectioncircuitsviaa600/120Vtransformer.~Provideapowersourceforcertaininterruptible120Vloads.TheEPS,whichprovidespowertoandcontrolstheoperationofelectrically-drivenplantauxiliaryequipment,canbefedfromanyoffourelectricpowersources:PlantTurbineGenerators,PreferredOffsitePower,AlternateOffsitePower,andEmergencyDieselGenerators.Duringnormalplantoperation,allauxiliarypowerissuppliedfromthegeneratorterminalsthroughthenormalunitauxiliarytransformers(1ABand1CD).Figure3.2-18showsasimplifiedone-linediagram.Figure3.2-17isasummaryofsymbolsandtheirmeaningsusedintheone-linediagram.Thereserveauxiliarytransformers(RATs)alsoprovidepowertothe4160Vswitchgearbussesduringstartuporshutdownoperations.Uponturbin~eneratortrip,thestationauxiliariesareautomaticallyandinstantaneouslytransferredtothePreferredOffsitePowerSourcereserveauxiliarytransformers(101ABand101CD)toassurecontinuedpowertoequipmentwhenthemaingeneratorisofftheline.ThePreferredOffsitePowerauxiliarysystemisarrangedsothatthe345MVAtertiarywindingoftransformerNo.4suppliestransformers101ABand101CD.Analternatesupplysourcefortransformers101ABand101CDisfromthe150MVA345/34.5kVtransformerNo.5whichisafullpoweralternatetotransformerNo.4.TheAlternateOffsitePowersourceisthe69kVDerby/Hoover/Ugine-Bridgmancircuitwhichsuppliespowertothetwo7500kVAemergencypowertransformers(EFI's)locatedintheirownstationneartheplant.(See3-99 Figure3,2-19.)Oneofthe7500kVAtransformers(12-EP-1)suppliespowerdirectlytothesafetybuseswithoutconnectiontothenon~etybusesthroughcircuitbreaker1EPlocatedinthestation.Theothertransformer(12-EP-2)suppliespowertotheVisitor'sCenter,RoadwayLighting,PlantSecuritySystemandothermiscellaneousloads.Thesecondtransformer(12-EP-2)isalsoabackupunitforthefirsttransformer(12-EP-1)andmaybeswitchedinplaceofthefirstifrequired.Therearenootherswitchingarrangementsforthispowersource.0)Eachunitalsohastwo4160V,3phase,60wycle,3500kWemergencydieselgenerators(EDG)whichareindividuallycapableofsupplyingpowertooperatetheengineeredsafetyfeaturesandprotectionsystemsrequiredtosafelyshutdowntheplantandavoidunduerisktopublichealthandsafety.The4160Vswitchgearisarrangedineightbussectionsperunitasfollows:Buses1A,1B,1C,and1Darenon-safetyclasswhileT11A,T11B,T11C,andT11Daresafetyclassbuses.Uponlossofpowertoa4160Vsafetybus,theassociateddieselgeneratorstartsautomaticallyandbeginstoacceptloadwithin10seconds.Theloadshedcircuitrywillautomaticallyopenthecircuitbreakerwhichnormallysuppliespowertothe4160Vsafetybusfromthe4160Vnon-safetybusandtripall4160Vsafetybusbreakersandnonessential600Vloads.ThecircuitbreakerfromtheEDGisthenautomaticallydosedtore-energizethe4160VsafetybuseswhentheEDGreachesratedspeedandvoltage.TheEDGswillthensupplyallequipmentwhichmustoperateunderemergencyconditions.TheEDGsarearrangedsothatEDG-1ABsuppliespowertosafetybussesT11AandT11BwhileEDG-1CDsuppliespowertosafetybussesT11CandT11D.The4160/600VACtransformersareenergizedfirst,thenthe4160Vsafetyrelatedmotorsandthe600VNonessentialServiceWaterPumpmotorsaretimesequencedbackontotheirrespectivebusesbyindividualtimerrelaysinthepumpmotorcircuitbreakers.The600Vsystemconsistsofsixbuseswhicharefedindividuallyfromthe4160VACsystemthroughsix4160/600Vtransformers,TRllA,TR11B,TR11C,TR11D,TR1BMCandTR11CMC.Fourofthe600Vbusesfeedsafetyandnon-safetyrelatedmotorsupto400hp.Eachmotor100hpormoreisfedthrougha600Vcircuitbreakerwhilemotors100hporlessarefedviamotorcontrolcenters(MCCs).Theothertwo600Vbusesfeednon-safetyrelatedloadslessthan100hpviaMCCs.The600Vbusesarelabeledasfollows:Buses11A,11B,11C,and11DservicesafetyclassequipmentwhileBuses11BMCand11CMCarenon-safetyclass.Ifrequired,each600Vbuscanbeelectricallyconnectedtoanotherbusviatheappropriatebuscrosstiecircuitbreaker.The600Vbuscrosstiebreakersdoseautomaticallywhenthe4160/600Vtransformerdifferentialorgroundovercurrentrelaysoperate.Thisautomaticclosurecanonlyoccurwhenoneoftheassociated600Vfeederbreakersisopenandbothofthebreakerswhichconnecttheassociated4kVbusestotheEDGsareopen.ThecrosstiebreakerscanalsobemanuallydosedusingcontrolswitchesontheStationAuxiliaryPanelintheControlRoom.ThecrosstiebreakersareautomaticallytrippedifeitherEDGstarts.Thebreakersare.asfollows:Buses11Aand11Carecrossconnectedviabreaker11ACandbuses11Band11Dareconnectedviabreaker11BD.Thereareatotalof18models(faulttrees)associatedwiththe4160VEPSandtheyaredesignatedasfollows:T11A,T11B,T11CandT11DThesemodelsdefinethelogicassociatedwiththeunavailabilityofthefour4.16kVsafetybusesduringallpostulatedaccidentswhenoffsitepowerisavailable.T11AP,TllBP,T11CPandT11DP11A,11B,Thesemodelsdefinethelogicassociatedwiththeunavailabilityofthefour4.16kVsafetybuseswhenthepreferredoffsitepowersourceislost.Thesemodelsdefinethelogicassociatedwiththeunavailabilityofthefour3-100 11Cand11D600VACsafetybusesduringallpostulatedaccidentswhenoffsitepowerisavailable.11AZ,11BZ11CZand11DZThesemodels,whichdefinethelogicassociatedwiththeunavailabilityofthefour600VACsafetybusesduringallpostulatedaccidentswhenoffsitepowerisavailable,areusedtopreventcircularlogicwhentwo600VACbusesarecrosstied.Inaddition,thesemodelsareusedtodefinethesystemlogicduringalossofoffsitepowerwhenautomaticbuscrosstieispreventedtoensurethatthedieselsarenotruninparallel.1ABand1CD-Thesemodelsdefinethelogicassociatedwiththestartingandoperationoftheemergencydieselgenerators.3-101 SwltcnyardCircuitBreakerakVor600VACCircuitBreakerTransformerComponent(Labeied)XXXSwitchFigure32-17ElectricPowerSymbols00'8-2:104904%I3-102 e~V)41AMCI1<CCLoZ~OlmCiPlZ345KV~oZC~alCiSK~RTUREC~NNlK2KlLTRANSF345KV45150hvaZr~345KVQH.,'C345KV345KVTRANSF<<4ZL-T=17~4345nvaBase345nvaTERTIARYA2-Alg~g~bl8OilB2-A~f0CGl'@765KV12ABNC.'2'D1300nvaTR-1UNITHEITRAHSF30nva30nva.ICDTRAINBTRAINAPREFERREDOFFSITEPOVER~SOURCE101AB30nva34$KV101CD30nva~f4KVZ1~4%201CD30nvaEHERGEHCYTIE2ABTR-2sTEp-up26KVOhva2CDTRAINBTRAINA765KV3433nva26KVIfZTSSZ1300nvaBaseUNITNORMALAUX.UNITNO.1.TRAINBUNITNO.I.TRAINAUNITNO.2TRAINAUNITNO.2TRAINBNORMAAUX-UNITPOVER-SOUR'GOHSITEEHERGEHCYDIESELGEHERATORSTRAINATRAINBZT=7ZUNITHILiAUXILIARIES+UNITHE2AUXILIARKSALTERNATEOFFSITEPQVERSOORCEDERBYHOOVERUGIHE-7500KVA4KVZT=7r.3-103.Figure3.2-18OffsitePowerSourcesSunpflfiedOne-Line~4'~9.20.50Soggg dtgtdcgg(QpP"R(I ICeaAIICTO545<<vLtscveeseo07(eve(45eCL<<l'h<<SKV0-ICItz(TlvoOLS<<vTR,soosiva~IS44torDiecvrcsos<<LII~ea4SISI~~IeVt77.$(v3-104FI'IHIIKILHIOTRICCo~sS,V<<,CPVS\ufit~ZI<<ILCVSKAPERiURECARlQ.@IAhoAvahaie~~pactumCardTR.IAZIzccvs(5cs/ca/soMVADerTR.ICDtFOICV>C3-I%4DOMvaTRIO(ASS(7ejt&SOMVA475ICVITRIO(Cos~lcvdufI%A/SOM57A4VCKVTR20tobA(L>NVIJsTRZOICD54SKVIo/IIL/doscva'dso/zA/Sot(vaITOCrr(IT'ToTt~IKKVIIUSO'P4ICVSUSIaYIIRCG3U24O(7ss(0~'~V4vs214f47Jv440~74'KVSS75IS<<IIIIa'.QkDICSClCCIIlaa~svIOIeeahch@4~IIrscO444vDIISTssDsrfo0((~DI~IlzcKcIIt75IC4f010YAKv~~II~scIAA44c4I4<<vDIISllsc4o4Is4A~~its)'s445500RICSCLCCICICO4CVESICTSIO~OlIIkmhQQtQgIce1tlPLP57ZLKpJz3Iyt44E<<vEBapYY~sIorrrick&4~Igzt4i'TOUs(ITIIIIChkh4IIIIII+41+IIIIIIIOIIIlrcaIIII!lII4GiRIICBdR47-:Mjllis~~4¹LZ'1Iis710LVeLiv445e3>>4'CzzvLvr44vaIPVCi7~SCLviaCuVDglv444Oz?viaTRIsrssaIDOOKvi~Si,ZOOOKVATR'toEooo'svATR<<DVC~Soo/Zoco<<A.~g/gCODTII.IKVCl500/'ZCOO<<AWVVX7C4ICDV4KDKKVACOOOCVA-<VArVPAVV-TIC,ISPIIC1000KVPI~IOSCI4SCOV4(OVDISSDOstaIIIv4vrovjg444s314Vvg'ItXzzz4'.4ICoo<<4<<CZZZrzZosS~IavIIIIIIIII-S44p4>>444gjzxl81stI',I-:=...-coooL~vt'404vfAvct~IPeIIDVIIOSIVvor44vvUCs4~I~is44L473tf4ie4~vvci4JZvl11Vvv3adPzFz44DO<<DissSt(VS(JJlIii-)ii>llgP+~KIIIIIII1111cesstsvc757ayXD'T*cs4VfHHE3'tII41~vFigure3.2-19AlteaOrrSi<ePo>ver'cp~D~eeIA~F'llTABIDestr59IC~I4StLr<<IC~Pi-'-.I<~Ie4C0<<,Cr~pvevwjcIst(4E<<<<ev~IIv\tIIteppsrp~I~~~I~"li.:I~tt<<IIv~LIV+vt+sv4'1I44RIUCLq'tKo03CzpOvW44K11\4g~oiDPVU414~V~<<44~TSV-uoi$(z444'VU1COOvBUSIIC~4C1~sLPVsCKi."*D)rtLv>>VV(doTrdgv)44Dod!~4t581ZSz(ScUV~vzpi~I11vvw(r~--51L4444LC4v~VNEIV71777(fgCOO(SUC~IAIIEIIDKsIi(7La'i".ll~'VP~L44De344rorj44~I4<<4rvILovVPV0d<<4Ã~I~IOZ<<vv0D~DooUpoot-LZeIrrrr\44~41~7~.44PzgvuvfvLe07%777ZCZ~vvv-gtztij~IVVisgrVLV141IE9'205050333/COCKCs(ISIlbCOCVOUSISS1l.ll11.11.1Ill11I.I'.Il11l<<DIggggcoslEs<<ltor@~~~oDcsz+E~3@J~~4~gg~~~II~~ss~~I7IIItttiII-IItIIihhhIhhOet~zvzttiIPzpgpv<<~4tv~4veevp(vale<<4vvtss0IVV~\<<4ep<<44s~~I~IS<<KII<<~teveevvCwossssc4stsotscavtlzclrscco,DONALDC.COOKICUQXAZtIAICI~tsc(vsiIsKPKsiAUX.ONF.LINeDIACILALIIrs(15IIPLLOFIIARFlG8I-IR5i<<<<seIpeI44'ti~I~V(rss'44Dz(IP(soliIIIVKI(DerICSOIDVSrAIE,ICIo-IcIFCIHIJIKILI1(INO7 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3.2.1.82250VDCSystemTheprimaryfunctionofthe250VDCsystemistoprovideareliablesourceofcontinuouselectricpowerforsupplyandcontrolofplantsafetysystems.Includedinthesesafetysystemsarethereactortripsystem,engineeredsafetyfeatures,andauxiliarysupportfeatures.The250VDCsystemconsistsofthreemajorbatterygroupsforeachunit:1)StationorHantBatteryTrainA(BusCDorGreenTrain)2)StationorPlantBatteryTrainB(BusABorRedTrain)3)NTrainBattery(TurbineDrivenAuxiliaryFeedwaterControlorBrownTrain)Po~erissuppliedfrom116(plantbattery)or117(N-trainbattery)individualcellswhichmakeupeachbatterysystem.Eachbatterygrouphastwoindividualbatterychargersthatmaintaineachtrainatitsratedstoredcapacityduringnormaloperation.ThebatterychargersarenormallyenergizedusingavailableACstationpower.Intheeventofalossofnormalstationandoffsitesystempower,theA&Btrainchargersareenergizedbytheemergencydieselgenerators.Asinglebatterychargerisnormallyinoperationprovidingpowertotheappropriatebusesandbatterygroup.Theremainingbatterychargerisinstandby.Thereexistsnoautomaticswitchoverbetweenbatterychargers.Intheeventofalossoftheworkingbatterycharger,manualactionsarenecessarytoalignthestandbybatterycharger.Thedistributionsystemforthe250VDCSystemiscomprisedofvariousdirectcurrentswitchgear,distributionpanels,bus,andindividualfeeders.TheDCswitchgearconsistsmainlyofdisconnectswitchesandfusesplusalimitednumberofmoldedcasecircuitbreakers.AnumberofdifferentDCplantloadsareservedfromeachofthemainandtransferdistributioncabinets.Theplantloadsincludecontrolcircuits(switchgear&annunciators),staticinverters,valvecontrolcenters,emergencylighting,andmotorcontrolcentersplusvitalbusinverters,fireprotectioncontrol,andmainturbinelubeoilpumps.TheNTrainBatterysuppliestheturbinedrivenauxiliaryfeedwater(TDAFW)controlbus,theATWSmitigationsystemactuationcircuitry(AMSAC)inverter,andavalvecontrolcenter.Theonlymanualactionsassociatedwiththissystemarethestartingofthestandbybatterychargerandtheclosingofmanualswitchesinordertoallowthefeedingofonetrainfromtheoppositetrain.Figure3.2-20showsasimplifiedone-linediagramrepresentingthe250VDCElectricPowerSystem.Therearefourmodels(faulttrees)associatedwiththe250VDCelectricpowersystem.Eachmodelrepresentstheunavailabilityofaparticular250VDCtransfercabinetordistributioncabinet.Themodelsaredesignatedasfollows:DCBThissystemmodeldefinestheunavailabilityof250VDCTrainBTransferCabinetTDABandDistributionCabinetsMCABandMDABundernormalACpowerconditions.DCAThissystemmodeldefinestheunavailabilityof250VDCTrainATransferCabinetTDCDandDistributionCabinetsMDCDandMCCDundernormalACpowerconditions.3-105 DCNThissystemmodeldefinestheunavailabilityof250VDCNTrainTransferDistributionCabinet1-DCNundernormalACpowerconditions.DCNSBO-Thissystemmodeldefinestheunavailabilityof250VDCNTrainTransferDistributionCabinet1-DCNunderstationblackoutconditions.3-106 OtVACC015CC~CCPCIICCtlVWCkffII~+CCICIC~IAAVAll~P0IIA~C(~'I(~IKIdC1114dd151I11CAIlttfCMW(CSl<ttIAIlfIfCNVOE1ICMlailafCAAP1C~I.A~IIAIIISAOAAICAI'llIKCIC~adIKOC00tflV~AOIC~Ct114VIAIIIIIAIIKA0A0IKAltIf0OIVAICtffttSIC0C154VIC111KII410VWCIVI11111~IIIC~AllftlOIACCIII1ft~IAII(tfCMAIKA111115MDCDMCCD1-CNHCABHDABIIIAA~KCI~ICIIILddd1KAIIfC.~OAOIIC,IKPIll0~I~IPIIAdf5CTDCDICIIC~001IIOCI'IOOII0II0UllI1TDABIOICSI.110~IACttfCICVIIOIICCIVCIIItOIt.0CIAfuWIVIIOIlOMkfl0011~KflAIICCIAIVACIIP.IINOIICFt.ltlll'IIPI~010tIIO'00115OI'ICIIPICO'~I~3-j.07Figure3.2-20250VDCElectricPowerSystemSimpliTiedOne-Line'Diagram 32.1.89120VACSystemTheprimaryfunctionofthe120VACelectricpowersystemistoprovideareliablesourceofelectricpowertoessentialinstrumentation,thereactorprotectionsystem(RPS),theengineeredsafetyfeaturesprotectionsystem,andthehydrogenigniters.'herearefour120VACvitalbusinstrumentsystemsineachunit.Eachdistributionsystem,commonlycalledaCRID(controlroominstrumentdistribution),consistsofastaticinverter,aregulatingtransformer,andadistributionpanelasshowninthesimplifiedone-linediagraminFigure3.2-21.EachCRIDhasfoursourcesofpower,anyoneofwhichcansupplysufficientpowerforCRIDoperation:1)Theoutputofaplantbatterycharger2)250VDCstationbattery3)600VACMotorControlCenter4)120/208VACdistributioncabinetCRP-3TheClass1Epowersources(Batterychargeroutput,250VDCstationbattery,and600VACmotorcontrolcenter)fortwoofthefourCRIDsareTrainAassociatedwhiletheothertwoareTrainBassociated.Thethirdsourceofpower,the600VACmotorcontrolcenter,feedstheregulatingtransformerbutisnotuninterruptible.Themotorcontrolcenteris,however,Class1E.Thef8hrthsourceofpower,120/208VACdistributioncabinetCRP-3,isnon-Class1Eandfeedsdirectlyintothedistributionpanels,bypassingtheinvertersandregulators.Transfersbetweenpowersourcesareautomatic(exceptforthenon-Class1Epowersource)anddonotdisturbvitalbusvoltageandfrequency.Alsoincludedaspartofthe120VACelectricpowersystemaredistributionpanelsAFWandELSC.Thesepanelsdistribute120VACpowertothehydrogenignitersandvariousplantinstrumentation.Eachpanelusesitsownindividualtransformertoconvert600VACpowerfroma600VAuxiliaryBusto120VACpower.Figure3.2-22showsthesimplifiedone-linediagramrepresentingsuchapanel.The120VACelectricpowersystemisrequiredtobeinserviceatalltimestoprovideacontinuoussourceofpowertoessentialinstrumentation,theRPSandengineeredsafetyfeaturesprotectionsystem.Undernormalconditions,theCRIDdistributionpanelsarefedfromtheoutputofthestaticinvertersthroughthetransferandbypassswitches.Normalpowertotheinvertersissuppliedbythe250VDCsystem.Duringnormalconditions,thestationbatterychargerssupplythenecessarypower.IntheeventofalossofACpower(foranyreason),thestationbatteriesprovidethe250VDCpowerneededbytheinverters.AnalternatesourceofpowertotheCRIDdistributionpanelsisobtainedfromtheregulatingtransformers.Thesetransformerstake600VACpowerfromthemotorcontrolcenters,transformitto120VAC,andfeedittothedistributionpanelsthroughthetransferandbypassswitches.Thisalternatesourceofpowerisengagedautomaticallythroughthetransfermvitchwithnodisturbanceofbusvoltageand/orfrequencywheneverpowerislosttothestaticinverters.Ifthealternatepowersource,the600VACmotorcontrolcenter,isunavailable,theCRIDdistributionpanelscanbeenergizedbymanuallyoperatingthemechanicallyinterlockedmainpanelcircuitbreaker,thusfeedingthedistributionpanelsfromtheBalanceofPlant120/208VACdistributioncabinetCRP-3.DistributionpanelsAFWandELSCarerequiredtooperateconstantlytosupplypowerforbothtrainsofthehydrogenigniters.Thesourceofpowertotheirrespectivetransformersis600VACBuses11Cand11B,respectively.3-108 Therearesixmodeh(fanlttrees)associatedwiththe120VACelectricpowersystem.EachmodelrepresentstheunavailabilityofaparticularCRIDorotherdistributionpanel.Themodelsaredesignatedasfollows:r4CRID1-ThissystemmodeldefinestheunavailabilityofCRIDIunderallACpowerconditions.CRID2CRID3120AFWELSCThissystemmodeldefinestheunavailabilityofCRIDHunderallACpowerconditions.ThissystemmodeldefinestheunavailabilityofCRIDIIIunderallACpowerconditions.ThissystemmodeldefinestheunavailabilityofCRIDIVunderallACpowerconditions.ThissystemmodeldefinestheunavailabilityofdistributionpanelAFWunderallACpowerconditions.ThissystemmodeldefinestheunavailabilityofdistributionpanelELSCunderallACpowerconditions.3-109 600VACAUXBUS250VDCDISTRIBUTIONCABINSI20/208VACDISTRIBUTIONCABINET'CRP-3'OOA50AISOLIDITERREQJLATINQTRANSljfIOKVA.600V-I20VIJT74KVASTATICINYER'TERIIIIIIIIIIIIIIIIIrIIgIIISTATICTRANsrERSVIIIIJHANIJAIIBYPASSSvIJHECHANICAI.INTERLOCKIIINC.NO.L'DISTRIBUTIONPANELvCNCRuALLYO'T0NL-NORMALLYZENFigure3.2-21Typical120VACVitalBusInstrumentSystemSimplifiedOne-LineDiagram110 600VACAUXBUSHCCTRaeSPGRKR"BOKVA600V/120VDISTRIBUTIONPANEL~C.-NCR<<L'"CLOSEDwQ-NORH+LLTOPENFlgUIC3)2-22Typical120VACPand(ELSC,AFW) 32.1.9MainFeedwaterandCondemnSystemsThefeedwatersystem(FW),inconjunctionwiththecondensatesystem,returnsthecondensedsteamfromtheturbinecondensersandthefeedwaterheaterdrainstothesteamgeneratorswhilemaintainingwaterinventorythroughoutthecycle.Thesesystemsautomaticallymaintainthewaterlevelofthesteaingeneratorsduringnormalunitoperation.Thecondensate/feedwatersystemprovidesacontinuousflowofwateratuniformtemperaturetoallsteamgeneratorsundernormaloperatingconditions.Thesystem,duringloadchanges,maintainssufficientfluidcapacitytoaccommodatechangesduetoexpansionandcontractionresultingfromthermalandpressureeffectsonthesteamgeneratorfluidinventory.SimplifiedflowdiagramsofthesystemsincludingthesupportingcirculatingwatersystemareshowninFigures3.2-23and3.2-24.Condensatecollectsinthemaincondenserhotwellsafterbeingcondensedinthemaincondensershells(A,BandC)andthefeedpumpturbinecondensers(whichgravityfeedtomaincondensershellB).Condensateisthenwithdrawnfromthecondenserhotwellsbythreehalf~pacitymotordrivenverticalhotwellpumps.Thepumpsdischargeintoacommonheaderwhichcarriesthecondensatethroughfourparallelsteamjetairejectorcondenserstothesuctionofthreehalf~pacitymotordrivenhorizontalcondensateboosterpumps.Thecondensateflowisthenpumpedbytheboosterpumpsthroughthreeparallelstringsofheaters(eachstringconsistsofaseparateexternaldraincoolerandalowpressureextractionfeedwaterheater).Downstreamoftheseheatersaretwoparallelstringsofthreestagesoflowpressurefeedwaterheaterswithintegraldraincoolers.ThecondensatefromtheNo.4heatersisthenroutedtotwohalf-capacitymainfeedpumpsviaacommonheader.Therearetwoturbinedrivenvariablespeedmainfeedpumpsinstalledinparallel,eachhasitsownsuctionstrainer.Minimumflowthrougheachpumpismaintainedbyemergencyleakoffvalveswithlineswhichterminateasspraypipesinthecondensers.Therecirculationvalvesopensequentiallyastheflowdecreasesbelow4000and2000gpm.Thefeedwaterfromthemainfeedpumpsisdischargedthroughtwo.parallelstringsofhighpressurefeedwaterheaters,eachstringconsistingofaNo.5andaNo.6heater.AfterdischargingfromtheNo.6heaters,'thefeedwaterisdistributedtothefoursteamgeneratorsthroughindividualfeedwatercontrolvalves.Uponreceiptofafeedwaterisolationsignal,thefeedpumpturbinesaretrippedandthemainfeedwatercontrolvalvesandthefeedpumpdischargevalvesdose.Therearethreemodels(faulttrees)associatedwiththefeedandcondensatesystems.Eachofthesemodelsrepresentstheunavailabilityofthissysteminresponsetodifferentaccidentevents.12FEEDThisfaulttreemodeledthefeedwatersystemfromthesuctionofthemainfeedwaterpumpstothedischargeofthehighpressurefeedwaterheaters.Faulttree13CONDMFiscalledinasasub-treetoaccountforcondensatefeedingthefeedwatersystem.Followingareactorscram,thefeedwaterpumpsaretrippedandthefeedpumpdischargevalvesareshut.Thismodelincludedcirculatingwaterflowtothefeedwaterpumpturbinecondensersandthemaincondensers.Successisachievedifonefeedwaterpumpflowpathisbroughton-line.13CONDThisfaulttreemodeledthescenarioinwhichthecondensatesystemisfeedingdepressurizedsteamgeneratorsthroughidlefeedwaterpumps.Thismodelincludedthefeedwatercontrolvalvesanddidnotrequirethesupportofthecirculatingwatersystem.Followingareactorscram,thetwooperatingboosterpumpsandthetwooperatinghotwellpumpswouldberecirculatingtothemaincondenser.Successrequiresonehotwellpump3-112 (operatingorthestandbypumpstarting)feedingoneboosterpump(operatingorstandbystarting)feedingtwooffoursteamgenerators.13CONDMFThisfaulttreeissimilartothe13CONDtreeexceptthistreemodelsthenormallineupwherethehotwellandboosterpumpsfeedoperablefeedwaterpumps.Again,thefeedwatercontrolvalveswereincludedinthistree.3-113 COeKN5(SAClllIAKIIAKIACNOtllCI)Sf~(CIICIAAIRNla(K10NANeCOel(NS(KS10NAIACONS(N5fllCIIK~t5$COel(ee5C~KIIIN(flCISSNK(CIt(IAAIIOe~a(K10NANI(OeS(55(NS(eKNIII5la(5le(C~IISNO'ISSN~(CIKIAAIIOe~a(K10Nate(OeKNS(KSCIISNCONS(N5(~CCIIIICKII(K1((eOtl)SfCANCCICNAIM~I51CNICCKAAOO~I10IflvlllfeOtllVfKVtelI5IO.tt(VfvftfAAK-AAtNSIleKIt~tIOt)tIVlllVtvOSVCKACCKl~fttIV10NAIe(OeL~C(S)IIK~CNStttfVIN)leo.tt)~1fVKNIIKllK<SfeO(5INItS)rto.tsfrv-oecrv.lls(Ctl)IAK~K)KtCeOttlSICNICt)ttvef(O~tttD4%tVACfCt(INCIAAV)4$CtISIIAt)CtISIIISSCt~ISIIIA11CtISIISSSIOICS5VALV(IOIAIIOII(10KIKNS~IrC.~rAA.S(505(et.Slat~51(ANJ(lAIK(l(CISAS3-11410NAIA(Oe)IFigure3.2-23Feedwater/CondensateSystemSimplifiedHowDiagram rlICOIIAII~'I'AOIIC10CDGLAIIASVIICASIICVAKCAWmIllCINKICCS'V'ASI~IVIO~IIV'IVAOI&CO>ICAIIAAv.\tItt.ttVNSIIIv-ISI'ltSIOCIKICAISISVAICAascwaCCtVW.COAKAICA~ItOeICACSAlCOIOCÃICACVII-SS~Figure3.2-24Cjrcula4ngWaterSystemSjmpljfjedFlowDiagramAClCACICCIVAVSA'.V(FItSIISttCPO'SIISAtA3-115 32.1.10MainSteamSystemThemainsteamsystemtransportssteamgeneratedinthesteamgeneratorsinsidecontainmenttoequipmentutilizingmainsteamlocatedoutsidecontainment.Forthisstudy,themainsteamsystemwillbeusedtoremoveprimarydecayheat,andisolatethesteamgeneratorsintheeventofasteamlineruptureorasteamgeneratortuberupture.Themainsteamsystemalsosuppliessteamtodrivetheturbinedrivenauxiliaryfeedwaterpump;however,thisfunctionismodelledwithintheauxiliaryfeedwaterfaulttrees.Themainsteamsystemisusedtoremovesteamfromthefoursteamgenerators.Thesteamisusedtoprovidecoredecayheatremoval.Inaddition,themainsteamisusedforthemotiveforcetoshutthesteamgeneratorstopvalvesforemergencyisolationofthesteamgenerators.Steamflowsthroughaseparatelinefromeachsteamgeneratorthroughasteamflowrestrictorthroughasteamgeneratorstopvalve.Oneachsteamgenerator,therearethefivesteamgeneratorsafetyvalvesandonepoweroperatedreliefvalve.Thesearelocatedbetweenthesteamflowrestrictorandthesteamgeneratorstopvalve.Followingthesteamgeneratorstopvalves,theindividualsteamleadscombineintoacommonheaderwhichequalizespressurebeforethesteamflowsintotheturbineadmissionvalves.Thisheaderisalsoconnectedtothesteamdumpsystem.Thesteamdumpsystemconsistsofninevalveswhichrelievesteamtothecondenser.Thissystemcanbeusedtocontrolreactorcoolantsystemtemperatureandpressureandremovecoredecay'eatfollowingaturbinetrip.Figure3.2-25representsasimplifliedone-linediagramofthesystem.Therearefourmodels(faulttrees)associatedwiththeMainSteamSystem.Eachmodelrepresentstheunavailabilityofthissysteminresponsetodifferentaccidentevents.Thissystemmodeldefinesthelogicassociatedwiththeresponseofthemainsteamsystemtoisolateatleastthreeoffoursteamgeneratorsduringasteamlineruptureevent.SSVThissystemmodeldefinethelogicassociatedwiththeresponseofthemainsteamsystemtomaintainintegrityofthefaultedsteamgeneratorduringasteamgeneratortuberuptureeventgiventhattheoperatorfailstostabilizeRCSpressurelessthansteamgeneratorsafetyvalvesetpoints.SGIThissystemmodeldefinesthelogicassociatedwiththeresponseofthemainsteamsystemtoisolateatleastonesteamgeneratorduringasteamgeneratortuberuptureevent.SGPORVThissystemmodeldefinesthelogicassociatedwiththeresponseofthemainsteamsystemtoanoperatorinitiatedRCScooldown.SuccessofthissystemmodelrequiresatleasttwooffoursteamgeneratorPORVstoopen.3-116' WTSIKI<<IIK10Aleesick<<TLOVICIPIILDetskIOfICSfe<<ekIPTIKIMyttteeOttl10AleeaoAI<<<<AVtt)IoIoIoAIILAIAAIII5vIv'IVsy'lv<<ly~Ittltfat~I~tIktSIC~1IOC1lafC10A'COOC<<KAIplkeI~vkvIIIC.~COLK<<letfp.ne.iavkv.an10ACOLK<<KAIp-Aaa-atvkv-lnfCfCISAloeSlLkvl)aloDcIaLCfTOIIICAToDCSILCTIINCAMv'tetMVt~f.aVtIKItea10AIIL~0lonl10fo<<kvte)AfnATILATILAllaA'nasv)~~TVtl~SvI<<svan-~I~'IAeIIIIioI10Ilkft<<TeaSILCKCO~Avtl)~010fo10lokinkiaaAIA~I<<~TeaISVSV5V5VSV<<ly1t)1'ta)~II)IASIICA<<TLOVICInk5ia~IIOC1laSick<<faovICia5/O~IIOC~IfClorCOIK<<KAI.Ile)5LOV.ITSfC10.r~COOC<<SCATYne-teafev.ata10AVTSfCMICkKO10OCOIKIOCAis<<lsa)IvkvIlkfC10't'OOC<<lckTI<<.sosttvkv-iteToDCllOTOIITee<AToDCStAIOOWICkVt~I10AfaaLIOAnaMvtnf0IOVtitMvtll10AIILloloTolo-foMytl)AlhkleLAllaAlnAIILSVIVSVsy5V<<syon1~).ItlItkI~IIIIAIIICA<<TLOV~ICIOkSIC~IIOK).Ian)lf)I.vkavcl4IATIDIKffatik)es'If.afkospc<<LIf.C.TkasCL055)Kfc<<CKCpay)coopIseastsP<<lSNSAlkO'Sails'tlIFI'llfll13-117Figure3.2-Z5MainSteamSytemSimplifiedHowDiagram 3.2.1.11PressurizerPowerOperatedRehefValveandSafetyValveSystemThepressurizer(PZR)isequippedwith3powerwperatedreliefvalves(PORVs),whichlimitsystempressureforalargepowermismatchandthuslessenthelikelihoodofareactortriponhighpressurizerpressure.Theoperationofthesevalvesalsolimitstheopeningofthespring-loadedpressurizersafetyvalves.Asix-inchrelieflineisattachedtotheupperheadofthepressurizer.Thelinedividesintothreeparallelthree-inchlines,eachcontainingapoweroperatedreliefvalveandamotoroperatedisolationvalve.Thereliefvalvesareactuatedbysignalsfromthepressurizerpressureinstrumentation.Actuationissettopreventoperationofthepressurizersafetyvalves.Amotoroperatedisolationvalveislocatedupstreamofeachreliefvalveandisclosedinordertoisolateaninoperablereliefvalveortoremovefromserviceareliefvalvewithexcessiveleakage.Downstreamofthepoweroperatedreliefvalves,thethreethree-inchlinesrecombineanddischargewiththepressurizersafetyvalvesintothepressurizerrelieftank.Figure3.2-26representsasimpliTiedone-linediagramofthesystem.ThePORVsrelyoncontrolairforactuationand250VDCpowerforthesolenoidsthatactuatethecontrolairtothePORVs.TheMOVsupstreamofeachPORVreceivetheircontrolpowerbyatransformationfromthe600VpowerthatoperatestheMOVs.Therearefourmodels(faulttrees)associatedwiththePZRPORVandsafetyvalvesystem.Eachmodelrepresentstheunavailabilityofthissysteminresponsetodifferentaccidentevents.PORVPThisfaulttree,whichispartofaprimaryfeedandbleedevent,modelstwooutofthreePZRPORVsrespondingtooperatoractiontoopenthemorfailingtostayopenonceopened.Themotoroperatedblockingvalvesalsohavetobeopened(alsotwoofthree)forthePORVstobeeffective.PZRSAFEThisfaulttreemodelsfailureofallthreesafetyvalvesandallthreePZRPORVstoopeninresponsetoananticipatedtransientwithoutscram(ATWS)eventifmanualrodinsertionisNOTsuccessful.PZRSAFE1ThisfaulttreemodelsfailureofallthreesafetyvalvesandoneofthePZRPORVstoopeninresponsetoanASSeventifmanualrodinsertionissuccessful.13PORVThisfaulttreeverycloselyresemblesthePORVPtreeexceptonlyoneoutofthethreePORVsisrequiredtoopen.ThistreeaccommodatesPORVresponsetoasteamgeneratortuberupture(SGTR)event.3-118 Og SV-45ALOOPSCALSV-45BSV-45CCQNVRQLAIRAV-153CA-554PRCSSVRIZCRRCLICITANKNHO-153NRV-153PR[SSURIZERCQN1RQL~AIRAV-152CA-565r.c.NHO-152NRV-152CONI'ROLAIRAV-151NHQ-151NRV-151RCFCRCNCCDRAVINGSiQP-I-5128A-27OP-I-5120D-3Figure3.2-26PressurizerPORVandSafetyValvesSimplifiedFlowDiagram3-119 3.2.1.12ContainmentAirRecirculationandHydrogenSknnmerSysteInThecontainmentairrecirculationandhydrogenskimmersystemhastwobasicfunctions.Oneisthegeneralrecirculationofthecontainmentatmospherebetweenupperandlowercontainmentsfollowingalosswf~olantaccident(LOCA).ThesecondisthepreventionoftheaccumulationofhydrogeninrestrictedareaswithincontainmentfollowingaLOCA.Thecontainmentairrecirculationandhydrogenskimmersystemconsistsoftworedundantindependentsystemswhichincludesfans,backdraftdampers,valves,pipingandductwork.Thesystemisnormallyinstandbyandisactuatedautomaticallybyahi-hicontainmentpressuresignal(2.9psig)ormanuallyfromthecontrolroom.Bothairrecirculationsystemshaveanairrecirculationfanlocatedintheuppercontainment.Eachsystemhasatotalcapacityof41,800cfm.Thefansdischargeviatheannularspacebetweenthecranewallandthecontainmentlinerintothelowercontainment.ThefansareprovidedwithbackdraftdampersonthedischargetopreventbackflowduringinitialLOCAblowdownintothelowercontainment.Eachairrecirculationfanhasitsownintakesystemwhichincludesthreeseparateheaders.Thethreeseparateheadersperformthefollowingfunctions:(a)Draw39,000cfmfromtheuppercontainmentintheimmediatevicinityofthefan.(b).Draw1,000cfmfromtheuppercontainmentatthetopofthedome.(c)Draw1,S00cfmfromthepotentialhydrogenpocketsinthelowercontainmentviaahydrogenskimmersystem.Thiscontinuousairflow(onceinitiated)isofsucharateastolimitpotentiallocalhydrogenconcentrations.Thepotentialareasofhydrogenpocketingare:thethreerooms(i.e.,eastandwestfanroomandinstrumentroom)intheannularspacebetweenthecranewallandtheliner,thetopofthesteamgeneratorandpressurizerenclosuresandthetopofthecontainmentdome.ThecontainmentairrecirculationandhydrogenskimmersystemisshowninFigure3.2-27.Thereisonemodel(faulttree)associatedwiththecontainmentairrecirculationandhydrogenskimmersystem.CFThecontainmentairrecirculationandhydrogenskimmersystemfaulttreemodeliscomprisedofbothtrainsofcontainmentairrecirculation(CEQ)fansystemsrespondingtoaPhaseBcontainmentisolationsignal.Successisachievedifoneofthetwotrainsbecomesoperational.Eachtrainconsistsoftheinletshutoffvalve(VMOvalve),theoutletbackdraftdamper,theCEQfanitselfandtheassociatedcomponentcoolingwater(CCW)valvesthatallowcoolingwatertotheCEQfanmotoraircooler.ThemotorwperatedCCWvalvesthatsupplyCCWtothemiscellaneousheaderarealsoincludedinthismodelinsteadofintheCCWmodels.Afailureofthesevalves(CMO415,<16,Q13,<11)doesnotaffecttheoperabilityoftheCCWtrains.3-120 0)O~

TOPOfCONTAINMENTUPPERCQNTOINHi=N1I(]POF'ONTAINMENtTOPOfSTEAMGENERATORANDPRESSURIZERDOGM[IUSESLOCALrANARI.AVHO101HV-CCO-ICCH-030UPPER+LOERIIHVCCO0011IICCH031ICCH.<33(lIIIICCH-032CONTAINHENTCONTAINHENTIIIIHV-CC0002HV-CCO-2<<-~lI(oVHO102LOCALF'ANAREAUPPERCONTAINMENTLOVERCONTAINMENTCOMPONENTCOOLINGVATERIIICOMP!1NENTCOOLINGVATERIIINSIRI.IHENTIownFAN/ACCUMULATORROOSTSILUPPERCONTAINHENTLOVERCONTAINHENTLOWERCDNTAINHI=N1'QIESREFERENCEDRALFINGSI.1.CCM-430,-431,-432,-433OP-1-5147A-'2AREOUTSIDEOfCONTAINMENTOP"I-5135B-I22.CMO"416,-415,-413,-411ARENOTSflOMNFigure3.2-27ContainmentAirRecirculationandHydrogenSkimmerSystemSimpliTiedFlowDiagrams3-121 3.2.1.13HydrogenIgniterSystemAdistributedignitionsystem(DIS)(alsoknownasthehydrogenignitersystem)isprovidedtoensureadequatehydrogencontrolincontainmentduringadegradedcorecoolingevent.TheDISutilizeselectricalresistanceheatingelements(glowplugs)locatedthroughoutthecontainmentbuilding.TheDISwillbemanuallyactuatedfromthecontrolroomwhencalleduponbytheEmergencyOperatingProcedures(EOPs).TheDISisatwo-trainsystememployingatotalof70igniterassemblieslocatedthroughoutthecontainmentbuilding.Thesystemwasinstalledinresponsetopost-ThreeMileIslandcontainmenthydrogencontrolconcernsandismeant,ingeneral,tolimitpost-accidenthydrogenconcentrations.Eachtrainof35igniterassembliesisfurtherdividedintotwogroups:onegroupof17assembliesisinthelowervolumeareaandthesecondgroupof18assembliesisintheuppervolumearea(includingtheicecondenserupperplenumvolume).Ignitersarelocatedabovethemaximumflooduplevelsandareplacedinregionsthroughoutcontainmenttopromotecombustionofleanhydrogen/air/steammixtures.ThesystemisshowninFigure3.2-28.Thereisonemodel(faulttree)associatedwiththeDIS.Thismodelrepresentsthesystemunavailabilityasitrespondstoactuation.ThisfaulttreemodelstheDISsystemsuchthatafailureoccursifbothTrainAandTrainBignitersineitherupperorlowercontainmentfailtoactuate.Failureofindividualglowplugsisnotincluded.3-122 UPPERCONTAINMENTOft'lflfOOIIOVCC~fflFVtRKLIIIVINIRAI~VISIStOOIIRSt~ISIIRWIISAICCIIIKVICSRKRIIRVIIS'IIStESII~I-CIIC-IStRRCCI'CISCIIAOI~ISI'CCCOIRIRICVCSILOVERCONTAINMENTOCCIOVLCCISt<ElSRSteelSaSIRIIISAIRJIRCCIRRARIORJRCCSt+IRIS1St&IIIII~IRKIIIII.CIICI~~OIKIIIIIICCRCIRIOIICSSCSrtCSICICRCRCCIRAVSOSfllSIRIS.I~51SIRIO.~ORISKS\~ICIRRRKC~IRRIKCOfIOCICIS~SRIISC.ICRIICCKXSWRIRCRRCR~((~CCIIIRCIOI3-123Figure3.2-28HydrogenIgniters(DistributedIgnitionSystem)SimplifiedFowDiagauns 32.1.14RefuehngCanalDrainsThreerefuelingcanaldrainsareusedtoreturncontainmentspraywaterinjectedintouppercontainmentbacktothelowercontainmentsump.Theconsequencesoffailureoftherefuelingcanaldrainsissevereinthatitwouldeventuallyprohibitemergencycorecoolingsystem(ECCS)andcontainmentspraysystem(CTS)recirculation.Thetwo12"andone10"refuelingcanaldrainconnectionsarebasicallyopenpipesintheflooroftherefuelingcanalandcontainnovalvesbutareequippedwithaflangeontherefuelingcanalside.Duringrefuelingoutages,thesedrainsarecoveredtoallowfillingtherefuelingcanalforfueltransportfromthereactortothespentfuelpool.Priortostartup,thecoversareremoved.Thedrainsareapproximately7.36'part,center-to~ter,andeachhasa1"lipabovethefioorelevation.Theyarelocatedintherefuelingcanal,justoutsideoftheremovablegateseparatingthereactorcavityfromtherefuelingcanal.3.2.2SystemAnalysisFaulttreeanalysiswasusedtomodeltheperformanceofplantsystemsintheCookNuclearPlantIPE.Theselogicmodelsdepictthevariouscombinationsofhardwarefaults,humanerrors,testandmaintenanceunavailabilities,andothereventsthatcanleadtoafailuretoperformagivensafetyfunction.Thedefinitionofsuccessforeachfaulttreeisdeterminedbythesuccesscriteriaestablishedforeacheventtreeheadinginvolvingsystemperformance.Faulttreesweredevelopedforbothfrontlineandsupportsystems.Theiranalysisisconditionalonboththeinitiatingevent(anditseffects),andtheavailabilityofsupportsystemsthatimpactsystemoperation.Thesupportsystemavailabilityisaccountedforbylinkingthesupporttreesintothefrontiinesystemfaulttrees.TheapproachusedtodevelopthefaulttreemodelsisconsistentwiththeguidanceprovideinReference26.CookNuclearPlantFaultTreeguidelinesweredevelopedtoensurethataconsistentapproachwasusedinestablishingmodelingassumptionsandinstructuringthemodels.Theyprovideguidanceinareassuchastheselectionofrandomhardwarefailurestomodel,treatmentoftestandmaintenanceoutages,modelingofoperatorerrors,andcommoncausefailureanalysis.Thefollowingprovidesanoverviewofthefaulttreeconstructionprocess.STEP1DevelopSimplifiedFlowDiagramAsimpliifliedflowdiagramwasdevelopedfromthedetailedplantdrawingsofeachmodelledsystemtoprovidethelevelofdetailrequiredforthemodelingofthesystem.Supportsysteminterfaces,normalcomponentposition,etc.,wereidentifiedonthesimplifieddiagram.Theplantdrawingsweresimplifiedthroughtheeliminationofflowpathsnotdirectlyrelatedwiththemainprocess(suchasfillandsamplinglines).Smalldivertedflowpathswhichdidnotcausefailureofthesystemwereremoved.TheoriginalCookNuclearPlantdrawingsfromwhichthesimplifieddiagramswerederivedwereidentifiedonthesimplifiedflowdiagrams.STEP2DevelopFaultTreeStep2.1Establishscopeoffaulttree-Thefaulttreeguidelineswereusedtoestablishwhatmodesandbasiceventsshouldbemodeled.Theyprovidedguidancetotheanalystforselectionoffaultspertinenttorandomhardwarefailures,testoutages,maintenanceoutages,humanerrorsandcommoncausefailures.Inaddition,theyprovidedguidanceontheexclusionofeventsthatdidnotneedtobeincludedduetotheirlowprobabilityofoccurrencerelativetootherevents(e.g.,passivefailureslikepiperuptures).Step2,2Usefaulttreemodulestodevelopfaulttree-Faulttreemodulesservedaslogicbuildingblocksintheconstructionoffaulttrees.Inaddition,theywereusedtosimplifyandstandardizefaulttreedevelopmentlayout.Modulesweredefinedforthesystemlevel,thenodelevel,thesegmentlevel,thecomponentlevel,and3-124 thecomponentinterfacelevel(actuation,electrical,etc.).Thesystemlevelmodulewasusedtorelatethesystemsuccesscriteriatothefaultlogic.Thenodelevelmodulesservedasinputintothesystemlevelmoduleandwereappliedtototallydefinethefaultlogicassociatedwiththesegments.Oncethenodelevellogicwasdevelopedandconstructed,thenextstepwastoestablishthe,faultlogicassociatedwitheachindividualsegment.Thiswasaccomplishedusingsegmentlevelmoduleswhichrelatedcomponentstothesegment.Finally,componentlevelmoduleswereusedtofurtherdefinefaultcontributionsrelatedtofailuremodeelementsofeachcomponentidentifiedinthesegmentlevelmodule.Theyrelatedtohardwarefailures,testandmaintenanceoutages,operatorerror,actuationsystemfailure,andsupportsysteminterfaces(e.g.,electrical,cooling).4'rocedureswereusedtodefinethestep-by-stepprocessinthedevelopmentofthefaulttreesusingthefaulttreemodules.Ruleswereappliedtodeterminethenodelevelmodulestobeusedbasedonthesystemsuccesscriteriaandflowrequirements.ThefaulttreewasdevelopedgraphicallywiththeWestinghouseGRAFTERCodeSystem(Reference10).STEP3QuantifyFaultTreeThefaulttreeswerequantifiedusingtheGRAF1'ERCodeSystem(Reference10)todetermineaninitialsystemfailureprobabilityandtoobtaintheminimalcutsets.Thecalculationalmethodsforquantifyingthebasiceventprobabilitiesthatwereinputintothefaulttreequantificationwerespecifiedintheproceduresmentionedabove.Calculationalmethodsweredescribedforhardwarefailures(bothdemandandtimedependent),maintenanceunavailabilities,testunavailabilities,humanerrorsandcommoncausefailures.Adiscussionofsystemmissiontimeswasprovidedandacomponentidentificationformatwasprovidedtomaintainconsistencywithintheanalyses.Step3.1Calculatebasiceventprobabilities-Utilizingthecomponentfailurerates,testandmaintenanceunavailabilitiesandotherbasiceventdata,thebasiceventprobabilitiesdefinedinthefaulttreewerequantifiedusingtheequationsprovidedinthetechnicalprocedures.Step3.2Calculatehumanerrorprobabilities-ThehumanerrorsconsideredinthedevelopmentofthefaulttreesandthehumanerrorprobabilitiesusedinthequantificationofthefaulttreesweredevelopedusingtheTHERPmethodology.Step3.3Calculatecommoncausefailureprobabilities-Onceafaulttreeforasystemwasdeveloped,theimportantcommoncausecomponentgroupswereidentifiedforinclusioninthefaulttrees.Thecommoncauseattributesthatwereusedfortheidentificationofcommoncausefailureswere:ComponentTypeComponentUse/Function(systemisolation,flowmodulation,etc.)Componentinitialconditions(i.e.,normallydosed,initiallyrunning,etc.)ComponentfailuremodeForeachcommoncausecomponentgroupidentified,commoncauseeventswereaddedtothefaulttree.Onceallimportantcommoncausefailureswereidentified,theMultipleGreekLettermethodwasusedtocalculatethecommoncausefailureprobability.Withthecommoncausefailureprobabilitiesinputintothefaulttree,thefaulttreewasquantifiedtodeterminethetotalsystemfailureprobabilityandtoobtainthedominantcontributors(cutsets)forthesystem.0'-125 STEP4DocumentProcessTheentireprocessoffaulttreedevelopmentincludingkeyassumptions,boundaryconditions,andotherimportantinformationwasdocumentedinthefaulttreesectionofthesystemnotebook.Thequantificationofthefaulttreewasdocumentedinthesystemnotebookinthequantificationsection.Thedominantcontributorstosystemfailureandkeyinsightswereidentifiedanddocumentedinthesystemnotebook.3.29SystemDependenciesTable3.2-3identifiesthefront-linesystemsorfunctionsthataredependentonthesupportsystemsandTable3.24identifieswhichsupportsystemsaredependentuponeachother.ThesupportsystemsmodeledincludeACpower,DCpower,componentcoolingwater,essentialservicewater,nonessentialservicewater,controlairandinitiationsignals.3-126 TABLE3.2-3FRONTLINESYSTEMDEPENDENCYONSUPPORTSYSTEMSFront-LineSystem/SupportSystem4160VAC600VAC250VDC120VACControlAirSignalsCCWESWAuxiliaryFeedwaterHighPressureInjectionHighPressureRecirculationLowPressureInjectionLowPressureRecirculationContainmentSprayInjectionContainmentSprayRecirculationMainSteamSGPORVsHydrogenIgnitersPzrPORVs&SafetiesContainmentFansMainFeedCondensateXXXXXXXXXXXXXXXXXXXXXXXXXXX,XXXXXXXXXXXXXXXXXXXX TABLE3.24SUPPORTSYSI'EMDEPENDENCYONSUPPORTSYSTEMSSupportSystem/SupportSystem4160VAC600VAC250VDC120VAC4160VACX600VACKX250VDC120VACControlAirXXXSignalsCCWESWNESWControlAirSignalsCCWDGsXXXXXXXXXXXXXXXXXX3-128 3BSeqiieaceQiantiTication3B.1ListofGenericData30.1.1ComponentIIiirdwareData,)GenericdataformedthebasisformanyofthecomponentfailureratesusedintheCookNuclearHantPRA.Ifashortageofplant-specificdataexisted,genericvalueswereutilizedaseithertheactualfailureratesorasthepriordistributionsforBayesianupdates.GenericfailurerateswereusedforthemajorityofelectricalcomponentsmodeledintheCookNuclearHantPRA.Table3.3-1listsallofthegenericcomponentfailurerates.References11,24,25,29and36wereusedforgenericdata.Reference29was,forthemostpart,thebaseforgenericdatausedintheCookNuclearHantPRA,includingfansusedforequipmentcooling.TheothersourceslistedabovewereusedwhenReference29didnotcontaindataforcomponentfailuremodesofinterest.3B.12InitiatingEventDataInitiatingeventsdatausedintheCookNuclearPlantIPEwastakenfrombothplantspecificandgenericsources.Genericdatawasusedtocalculatetheinitiatingeventfrequencyofthoseeventsnotexpectedtooccurduringthelifeoftheplant.ForLOCAevents,Reference36wasusedasthesourceofpipebreakfrequencies.CalculationofvalvefailurefrequenciesleadingtoLOCAsutilizedthecomponentfailuredatadiscussedabove.ThefrequenciesofsteamgeneratortuberupturesandreactorcoolantpuinpsealLOCAsweredeterminedusingproprietarydataprovidedbyWestinghouseElectricCorporationinReferences68and69,respectively.32DHantNpecificDataandAnalysis322.1ComponentHardwiireData0)PlantspecificdatawascollectedveryearlyinthePRAproject.AlistofcomponentsforwhichdatawastobecollectedwasgeneratedbasedontheresultsofindustryPRAsandontheopinionsofutilityandcontractorpersonnel.Thislistwasusedtofocusthedatacollectioneffort.MostofthemechanicalandtestingdatausedintheCookNuclearPlantPRAutilizedplant-specificdatatocalculatefailureratesthroughclassicalmeansorthroughtheuseofBayesiantechniques.Table3.3-1listsalloftheplantwpecificcomponentfailureratesandtheirrespectivecalculationaltechniques.ThosefailureratescalculatedusingBayesiantechniquesusedgenericpriorfailureratesfromthesourcesidentifiedinSection3.3.1.322.2InitiatingEventDataAnanalysisofallunittripssincethestartofcommercialoperationwascompletedandprovidedthefrequencyoftransienteventsfortheCookNuclearPlant.ForspecialinitiatingeventssuchaslossofCCW,thefrequencyofoccurrencewascalculatedusingfaulttreeanalysistechniquesandcomponentfailuredatafromthemasterdatafile.3-129 DESCRIPTIONTABLE33-1DATAPROCESSINGTABLEUNITSGEN.PROBGENiVARNMCALCiPROBCALC,VAR12COMMENTS026CentrifugalChargingPump027CentrifugalChargingPump/D/Hr3.0E-033'E-055'8E-0507506.66E-045.48E-091752721'3E-54'8E-079.94E-11BayesianPlant028MotorDrivenAFWPump/D029MotorDrivenAFWPump/Hr*030TurbineDrivenAFWPump/D031TurbineDrivenAFWPump/Hr032ContainmentSprayPump/D033ContainmentSprayPump/Hr034EssentialService'Water/DPump3.0E-033.0E-053~OE-025.0E-033'E-033OE-053'E-03548E-05548E-095.48E-031~52E-045'8E-055.48E-095.48E-050179088.6052~10'501.32E-033'E-054.40E-022.86E-03115E-0304129'9E-040187'3.0E-052'2E-065'8E-091~09E-031+79E-05lo99E-065'8E-091~08E-06BayesianGeneric*SeeNoteBayesianBayesianGenericBayesian035EssentialServiceWater/HrPump3'E-055.48E-091.752481~33E-059'4E-11Plant036SafetyInjectionPump037SafetyInjectionPump038Non-EssentialServiceWaterPump/D/Hr/D3'E-033.0E-053.0E-035.48E-05548E-095.48E-0512382'8E-03273F43.0E-051358.85E-03771E-065'8E-091,16E-04BayesianGenericBayesian039Non-EssentialServiceWaterPump/Hr3~OE-055'8E-0922257388'6E-064'1E-11Plant*NotesCalculationincludesBayesianupdatedfailureratesoftrip/throttlevalveandpump/turbine3-130 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLEUNITSGEN~PROBGEN,VARNMCALC.PROBCALCVAR12COMMENTS040ComponentCoolingWater/DPump041ComponentCoolingWater/HrPump3'E-033.0E-055,48E-0503729,55E-045.48E-090752366'5E-061~23E-064'7E-11BayesianBayesian042ResidualHeatRemovalPump043ResidualHeatRemovalPump/D/Hr3'E-033.0E-055.48E-0502751.10E-035.48E-091123.43.0E-051.77E-065'8E-09BayesianGeneric044CirculatingWaterPump/D045CirculatingWaterPump/Hr046FeedwaterPump047FeedwaterPump048HotwellPump049HotwellPump/D/Hr/D/Hr050CondensateBoosterPump/D051CondensateBoosterPump/Hr067DieselDrivenFirePump/D068DieselDrivenFirePump/Hr069AirCompressor(Fails/DtoStart)3.0E-033'E-053'E-025'E-033'E-033'E-053'E-033.0E-053'E-028OE<<048'E-025'8E-05548E-095.48E-031.52E-045.48E-055.48E-09548E-055,48E-095.06E-043.90E-063'E-033.0E-0312609373.83E-063'E-0201504921.82E-033.0E-0321504921.33E-053'E-030150492444E-063OE-028.0E-048.0E-025.48E-058'6E-125'8E-037+41E-115'8E-059'4E-.115'8E-051.82E-ll506E-043'0E-063.6E-03GenericPlantGenericBayesianGenericPlantGenericBayesianGenericGenericGeneric3-131 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLEUNITSGEN,PROBGEN.VARNMCALCiPROBCALC.VAR12COMMENTS070AirCompressor(FailstoRun)/HrF08-042.44E-072+08-042'4E<<07Generic076MotorOperatedValve(FailToActuate)/n3'E-035'88-0519125591'1E-031~288-06Plant077MotorOperatedValve/Hr(FailuretoRemainClosed)5.0E-071528-12--5'E-071.528-12Generic078MotorOperatedValve(FailtoRemainOpen)/Hr1~OE-07562E-15---F08-075'2E-15Generic079SolenoidOperatedValve/D(FailureToOperate)2.0E-03225E-06----2'E-032'5E-06Generic080HydraulicValve081AirOperatedValve082CheckValve(FailstoOpen)083CheckValve(FailstoClose)084PowerOperatedReliefValve(PORV)(FailtoOpen)085PowerOperatedReliefValve(FailtoRecloseOnceOpen)/n/D/n/D/n/n2.0E-032.0E-031.0E-041~OE-032+08-032'E-035.628-091.08>>045.62E-07---F08-032258-060482OE-032'58-06-<<-2'E-032'5E-062'E-032258-06022467'9E-042'58-061~68E-075'2E-095'2E-072.25E-06225E-06GenericBayesianGenericGenericGenericGeneric086PressureRegulatingValve(FailstoOpen)/n2OE-03225E-062.OE-03225E-06Generic3-132 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLEUNITSGEN~PROBGEN.VARNMCALC.PROBCALCoVAR12COMMENTS087ReliefValve(FailstoOpen)/n3.0E-045.48E-073.0E-04548E-07Generic088MainSteamIsolationValve(MSIV)/D2.0E-032.95E-061216-2.41E-032,50E-06Bayesian089ReliefValve(FailstoReclose)090AirOperatedValve(SpuriousClosure)091AirOperatedValve(SpuriousOpen)092ManualValve(FailstoOpen)093CheckValve(DiscRupture)094MotorOperatedValve(DiscRupture)/n/Hr/Hr/n/Hr/Hr2OE-021~OE-075'E-071OE-041'E-071~OE-072.25E-04--2'E-025'2E-15---1~OE-071.52E-12--5.0E-Q75.62E-091~OE-045'2E-15---1.0E-075.62E-15--1.0E-07225E-045'2E-151~52E-125'2E-095.62E-155.62E>>15GenericGenericGenericGenericGenericGeneric095ReliefValve(FailstoOpen)/D3.0E-045.48E-073OE-045.48E-07Generic096ReliefValve(FailstoReclose)097StopCheckValve(FailstoOpen)098SafetyValve(OpensPrematurely)/n/n/Hr2'E-021OE-043OE-062.25E-04---2'E-025.62E-09--1~OE-045.48E-11--3.00E-062'5E-045.62E-095'8E-11GenericGenericGeneric3-133 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLEUNITSGEN+PROBGEN.VARNMCALC.PROBCALC.VAR12COMMENTS3099SCRAMSystem(FailuretoSCRAM)100PressurizerSafetyValve(PrematurelyOpens)126Fan(FailstoRun)'D/Hr/Hr3oOE-053OE-061'E-055.06E-10---3.0E-055.06E-1212257383'3E-065.62E-111~OE-055.06E-104.02E-125.62E-11GenericBayesianGeneric127Fan(FailstoStart)/D128FanCorrectiveMaintenance/D152Orifice(Plugged)/D153Orifice(Plugged)/Hr154Orifice(Rupture)/Hr155Damper(FailtoOpen)/D156Damper(FailtoOperate)/Hr157AirCooler(FailtoOperate)/Hr158HeatExchanger(Rupture)/Hr159HeatExchanger(Blockage)/Hr160Strainer/Filter(Plugged)/Hr161PipePlug/Hr(BoronPrecipitation)3'E-042'E-033~OOE-046OOE-073.0E-083OE-031OE-061OE-063OE-065'E>>063OE-057.7E-075.06E-082.44E-055.06E-082'2E-135'6E-16548E-056.09E-12562E-135'8E-ll1~98E-10548E-093.33E-133.0E-042'E-033.00E-046~OOE-073'E-083.0E-031'E-061~OE-063OE-065'E-063OE-057'E-075'6E-082'4E-055.06E-082.02E-135'6E-165.48E-056.09E-125.62E-135'8E-11.198E-10548E-093'3E-13GenericGenericGenericGenericGenericGenericGenericGenericGenericGenericGenericGeneric3-134 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLEUNITSGENoPROBGEN.VARNMCALC~PROBCALCVAR12COMMENTS3162TankPlug(BoronPrecipitation)/Hr7~7E-073~33E-13---7~7E-073.33E-13Generic163Tank(Rupture)/Hr8'8E-10510E-178.48E-105'0E-17GenericLines251-376representunavailabilities,notfailurerates.Theunavailabilityiscalculatedfromtheproductofthefailurerateandtheaverageduration.251OHP4030eSTP~002V253OHP4030~STP~007E255OHP4030'TP~007W257OHP4030'TP011265OHP4030'TP+017E269OHP4030.STP~017T271OHP4030STP~017W273OHP4030STP019F275OHP4030'TP019P277OHP4030'TP~020E279OHP4030'TP~020W281OHP4030'TP~022E283OHP4030'TP+022W285THP4030.STP~209/n/D/n/D/n/n/n/n/n/n/n/D/n/D5.03E-038.33E-03785E-033.39E-036.10E-034.98E-033.32E-039'5E-043'1E<<042i68E-039.41E-035.28E-03169E-027'8E-041.42E-053'0E-053'7E-056'5E-06209E-051~39E-056'1E-064.92E-078.60E-084.04E-064'8E-05157E-051~60E-043'4E-07PlantPlantPlantPlantPlantPlantPlantPlantPlantPlantPlantPlantPlantPlant3-135 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLEUNITSGENoPROBGEN,VARNMCALCoPROBCALCoVAR1:2COMMENTS3289OHP4030'TP~050E291OHP4030'TP~050W293OHP4030'TP.051N295OHP4030.STP.051S297OHP4030.STP.052E299OHP4030'TP.052W301OHP4030'TP~053A303OHP4030~STP~053B304OHP4030'TP~018305PP-1CorrectiveMaintenance307PP-1PreventiveMaintenance/D/D/D/D/D/D/D/D/D/DNoDurationPresentlyAvailableNoDurationAvailable4OOE-031~45E-032.36E-032.70E-033.31E-033'4E-037'2E-030'1.20E-030.04'7E-038.97E-061~19E-063.14E-064.09E-06615E-065.56E-062'7E-058'9E-071.17E-05PlantPlantPlantPlantPlantPlantPlantPlantPlantPlant309PP-2CorrectiveMaintenance310PP-2PreventiveMaintenance311PP-3PreventiveMaintenance313PP-3CorrectiveMaintenance/D/D/D/DNoDurationAvailable4'2E-04201E-044'2E-040.09.08E-OS2'7E-089'4E-OSPlantPlantPlant3-136 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLE12UNITSGENoPROBGENeVARNMCALCoPROBCALCVARCOMMENTS315PP-4PreventiveMaintenance317PP-4CorrectiveMaintenance319PP-5CorrectiveMaintenance321PP-5PreventiveMaintenance/D/D/D/D1.53E-031.158-037,67E-043,04E-041.32E-067'3E-073.318-075'9E-07PlantPlantPlantPlant323PP-6CorrectiveMaintenance/DNoDurationAvailable0.0325PP-6PreventiveMaintenance327PP-7CorrectiveMaintenance329PP-7PreventiveMaintenance331PP-8CorrectiveMaintenance332PP-8PreventiveMaintenance333PP-9CorrectiveMaintenance334PP-9PreventiveMaintenance/D/D/D/D/D/D/DNoDurationAvailableNoDurationAvailable1.75E-020.01~48E-03198E-032.91E-020~OOE+003'28-051728-041~23E-062'0E-064'68-045'7E-10PlantPlantPlantPlantPlant3-137 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLEUNITSGEN.PROBGEN.VARNMCALC.PROBCALCVAR12COMMENTS335PP-10PreventiveMaintenance/D3.038-035.168-06Plant337PP-10CorrectiveMaintenance/nNoDurationAvai.lable0+0339PP-26PreventiveMaintenance/n3'28-046'6E-OSPlant341PP-26CorrectiveMaintenance/nNoDurationAvailable0~0343PP-35PreventiveMaintenance/n7.39E-043+078-07Plant345PP<<35Correcti.veMaintenance/nNoDurationAvailable0'347PP-50CorrectiveMaintenance/DNoDurationAvailable0.0349PP-50PreventiveMaintenance350AirCompressorCorrectiveMaintenance/n/D2OE-03F858-0342'48-05---2'E-034'7E-06244E-05PlantGeneric351AirCompressorPreventiveMaintenance359FWPumpTurbineCondenserPreventiveMaintenance365PORVCorrectiveMaintenance/n/n/nNoDataAvai.lable0.02'48-048'5E-024e538-084.308-03PlantPlant3-138 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLEUNITSQEN,PROBGEN.VARNMCALC~PROBCALC.VAR12COMMENTS366PORVPreventiveMaintenance369SGPORVPreventiveMaintenance/D/DNoDurationAvailable0~OOE+007'4E-033'1E-05Plant371AirOperatedValvesCorrectiveMaintenance/DNoDurationAvailable0.0372AirOperatedValvesPreventiveMaintenance/D3.728-067'8E-12Plant373MOVCorrectiveMaintenance374MOVPreventiveMaintenance/D/D2'2E-054'5E-052o77E-101~38E-09PlantPlant375Aux.BuildingExhaust/DFanCorrectiveMaintenance376Aux.BuildingExhaust/DFanPreventiveMaintenanceNoDurationAvailable001~66E-031~558-06Plant400DieselGenerator401DieselGenerator402HydrogenRecombiner403HydrogenRecombiner405ManualSwitch(FailstoOperate)/D/Hr/D/Hr/Hr3'E-022'E-031OE-065068-042'2E-05562E-135377'5E-031107'9.03E-04519'0E-0319.52.568-021~OE-063.128-054'8E-075'0E-053'88-045'2E-13PlantPlantPlantPlantGeneric3-139 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLEUNITSGEN~PROBGEN~VARNMCALC,PROBCALCVAR12COMMENTS406CircuitBreaker(SpuriousOpen)407CircuitBreaker(FailstoTransfer)/Hr/D1'E-063'E-035.62E-131.0E-065.48E-053.0E-035'2E-135.48E-05GenericGeneric409Bus(FailsAllModes)410CurrentTransformer411PotentialTransformer412Power'ransformer413ProcessTransformer414RelayContacts(FailtoTransfer)/Hr/Hr/Hr/Hr/Hr/Hr408Fuse(OpensSpuriously)/Hr3.0E-061OE-076.0E-076OE-076'E-076'E-071~OOE-065.06E-121.60E-142'2E-132.02E-132.02E-13202E-135'2E-133.0E-061.00E-076,0E-076'E-076.0E-076.0E-071OOE-06506E-121.60E-142'2E-132'2E-132'2E-132.02E-135.62E-13GenericGenericGenericGenericGenericGenericGeneric415RelayCoil(OpenorShort)/Hr3.0E-065.06E-12----3OOE-065'6E-12Generic416TimeDelayRelay(PrematureTransfer)/Hr1.0E-065'2E-131OE-065'2E-13Generic417BimetallicTimeDelayRelay418Battery419BatteryCharger420BatteryCharger/Hr/Hr/Hr/D1~OE-051~OE-061OE-063'E-045.62E-111OE-055'2E-13---1OE-065'2E-13--1OE-06548E-07->>-3OE-045.62E-115'2E-135'2E-13548E-07GenericGenericGenericGeneric3-140 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLEUNITSGEN.PROBGENoVARNMCALC.PROBCALC.VAR12COMMENTS421DCMotorGenerator422Invertor423WiringFails(OpenCircuit)424WiringFails(ShorttoGround)425WiringFails(ShorttoPower)426SolidStateDevice(HighPower)427SolidStateDevice(LowPower)428SolidStateDevice(Bistable)429TerminalBoard(OpenCircuit)430TerminalBoard(ShorttoAdjacentCircuit)/Hr/Hr/Hr/Hr/Hr/Hr/Hr/Hr/Hr/Hr3.08-061OE-04F08-05108-063.08-083,0E-063'E-063.08-073.08-073.08-075.488-113'E-065.62E-091.08-045.628-11---1'E-055.62E-131.0E-065.068-16308-085.488-113.08-065'88-113.0E-065'88-133'E-075.488-133.0E>>075'88-13--3+08-075.48E-115.628-095.62E-115~628-13506E-165.488-115'88-11548E-135488-135'88-13GenericGenericGenericGenericGenericGenericGenericGenericGenericGeneric431TorqueSwitch(FailtoOperate)432LimitSwitch(FailtoOperate)/Hr/Hr2.0E-076o08-062'58-142028-112.0E-076o08-062.258-142'2E-11GenericGeneric3-141 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLEUNITSGENPROBGENVARNMCALCoPROBCALCVAR12COMMENTS3433PressureSwitch(FailtoOperate)434FlowSwitch(FailstoOperate)435FlowSwitch(FailstoOperate)436-Relay(FailstoOpen)437Relay(FailstoClose)438LimitSwitch(FailstoOpen)/Hr/o/Hr/n/O/o2'E-074.0E-OS3'7E-06209E-062OOE-061.00E-042'5E-148.99E-167.57E-112.46E-122.25E-125'2E-092.0E-074'E-083'7E-062.09E-062~OOE-061~OOE-042'5E-ll8'9E-167.57E-ll2.46E-122.25E-125'2E-09GenericGenericGenericGenericGenericGenericLines451-487representunavailabilities,notfailurerates.Theunavailabilityiscalculatedfromtheproductofthefailurerateandtheaverageduration.439LimitSwitch(FailstoClose)/n1~OOE-045.62E-091~OOE-04562E-09Generic451HydrogenRecombinerTest/D453DieselGenerator/nCorrectiveMaintenance7'1E-052'6E-043.51E-092'7E-08PlantPlant454DieselGeneratorPreventiveMaintenance/n4'7E-04107E-07Plant459OHP4030.STP.013A461OHP4030.STP.013B485OHP4030'TPo027AB/n/n/o3'5E-04269E-046'1E-036.30E-064.06E-082.03E-05PlantPlantPlant,3-142 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLE12UNITSGENoPROBGENoVARNMCALCoPROBCALCoVARCOMMENTS487OHP4030'TP.027CD654GenericHEPg8655GenericHEPg9656GenericHEP116657GenericHEP117658GenericHEPf18659GenericHEPf19660GenericHEPf20661GenericHEP421662GenericHEPf22663GenericHEPf23664GenericHEPf27665GenericHEPf39666GenericHEPf40667GenericHEPg51/n/n/n/n/n/n/D/n/n/n/n/n/n/n/n1.30E-021~30E-023.80E-031~30E-028.10E-021~60E-023.80E-03I1.30E-031~30E-031.30E-03270E-03270E-041.60E-033+75E-0388E-051.1E-037,9E-0688E-051.0E-0242E-047'E-0688E-0711E-051~1E-054.3E-0543E-07160E-057'0E-065.33E<<031.30E-021.30E-023.80E-031~30E-028'0E-021.60E-023.80E-031.30E-031~30E-031.30E-032'0E-032.70E-041~60E-033'5E-031~60E-058.8E-051.1E-037'E-068+8E-051.0E-024.2E-047.9E-068.8E-071.1E-051~1E-054,3E-054'E-071~6E-057.90E-06PlantGenericGenericGenericGenericGenericGenericGenericGenericGenericGenericGenericGenericGenericGeneric3-143 DESCRIPTIONTABLE3.3-1(Cont'd.)DATAPROCESSINGTABLEUNITSGENoPROBGEN.VARNMCALC.PROBCALC~VAR12COMMENTS3668GenericHEPg52671GenericHEPf26/D/D7'08-032.70E-043.16E-05---F508-034'8-07---2.70E-043'6E-054.3E-07GenericGeneric1N=Numberoffailures.Insomecasesadash(-)appearswhichmeansnodatawascollectedforthisentry.2M=Numberofdemands/hoursofoperation.Insomecasesadash(-)appearswhichmeansnodatawascollectedforthisentry.3Bayesian=BayesianUpdate,Plant=PlantSpecific3-144 o",3.3.3HumanfailureData399.1GeneralApproach>n<<>.r.9IC~r..f;ih',Thegeneralmethodologyusedinquantifyinghumanerrorprobabilities(HEPs)wasastep-by-steptaskanalysis..Eachgeneraloperatoractionwasbrokendowp'intoascrip,'qfsubtasCs,(discretephysicalormentalsteps).Inaddition,specificactivitieswhichcouldservetodisablethesystemorwhichneededtobe.performedduringtheaccidentwerealsoexplicitlymodeled.ThesesubtaskswerethenquantifiedbyassigningconditionalHEPsassociatedwiththespecificsubtask.TheconditionalHEPswereassignedusingTechniqueforHumanErrorRatePrediction(THERP)jnethodology(fromReference22)toanalyzeindividual.tasPj,,definedip.taskanalysis.he.',gEPtasso'ciated",with'thegenjxQoperatoractionwasquantifiedpjingengineeringcalculationsor'(aulttreemodels(providessamecalculationalresultsasTHERPtrees),asappropriate.TheoverallstepsinperformingthisevaluationforthequantificationoftheHumanErrorProbabilitiesassociatedwith.the.CookNudearHantPRAwereasfollows:pr<~<~+~~<i~~'WlC322.1.(~incOperatorAdionsandOtherHumanInteractionsDefineeratorAction.inEvntTr~/~KFor,,pperator~ptipgsappearingineventtrees,thefollowinginformationforeachoperatoractionwasPm.,<~,u.<il~F,shia$+A"u<io<'.Q</pl"b.Descrip'onof'Action;c.TimeWindowAvailableforAction;d.ApplicableProcedures;e,;$pdication,of~etherthe,ActionWasSimulatedinTraining.<~<i<I<~y<~~."<'a~Notethatatthispoint,theanalystestablishedthe'definition,scopeandsuccesscriteria.'otheoperatoractionsmodeledintheeventtrees;nohuman,retiabilitymodelingwasperformedyet.llj)<.g~Thistask,wasanalogoustothetaskofdefiningthesuccesscriteria,missiontime,andsystemboundaryof~ot)egepent,gee.nodestoprepareforthefaulttreeanalysis.;li~)gllajl<<ia+i<'g",-',.ij~~fl,'<o<~""'~.".o~V.<i.i.&VIsf>"'.<i<<'),it'ai<<'o<I&<<j1!<iForotherhumanerrorsneededinfaulttreeanalysis,eitherthefaulttreeanalystprovidedhis/herown<<calculationfora.HEP,usingdatafromthemasterHEPdatabanksuppliedbytheHumanReliability'.Analysis.(HRA)analyst,orthefaulttreeanalystrequestedtheHRAanalyststocalculateanddocumentsuchanPEP..329.12ModelEachOperatorAction/Humanlnteraction,..:"c'ii'oii',~ic'.,a~a'.'",,'.),.",t.'.,Inthistask,thehumanactionsdefinedinstep3.3.3.1.1werebrokendownintosmallersubtasksforwhich.,potentialhumanerrorsandassociatedHEPscouldbeassigned.(Table3.3-2listsgenericHEPsobtainedfromReference22whichwereusedasabasisforcalculationofhumanerror.)Keysubtasks~oWereidentifiedandretained,otherswereeliminated.Plantspecificconsiderations(e.g.,operatortraining,,existenceofprocedures,operatorstresslevels,etc.)werethendeterminedand,collectively,wereusedto3-145 calculateaPerformanceShapingFactor(PSF).ThePSFwasusedasamultiplieronagenericHEPtocalculateaplantspecificvalue.GuidelinesusedincalculatingPSFsareidentifiedinReference22andinTable3.3-3.),~Eachmodeliseither:f"-fi)v,<<~PIIIa.asimpleafgebraicsum/productmodel;orb.afaulttree.~~399.19VisitHantandInterviewOpeartorsJ)-.".,IlNIe.,Aspartofthe,Quantification.'ofHumanError'roballities,'hplantvisittd'intervirbw'the"operatorsandotherplantpersonnelaboutthehumanactionsthataremodeledinstep3.3;3.1.2"4iIs'made.Theobjectivesofthistaskwereasfollows:a.Verifythemodelsandassumptionsthroughdiscussionswiththeplantpersonnel.trjis<'sal'0Pb.AssesstheadditionalPSFsthatmaymodifythenominalHEPsinthequantiTicationteak.c,IdentifythoseactionsthatmaybesubjecttoascreeningprocesswithoutfurtherquantiTicatjon.".<a)I3.32.1.4QuantifyHEPSforeachOperatorAdion/HumanInteraction.i.ts..afrInthisstep,theanalystperformedadetailedquantiTicationoftheHEPsfortheopdat3racdtioits",UsingamasterdatabankobtainedfromReference22andapplyingthePSFs.Ifnotalready,.identifieditfiePSFs)veredeterminedatthispoint.Forconvenience,tablesI'romthemasterdataSlickare'!'a)sided,tnTable3.3-2.IvcrfC~t~~w)cmv'c~~arl)f>>DetailedHEPuantificatinve~v=rIForthistask,.theoperatoractionswerequantifiedbyusingtherulesofTHERPmethodplogyutilizingthe)eivLIa.GenerationoftheHumanErrorProbabilityD'ataBink'.".'Thistaskinvolved'thegeneratingofamasterdata;bankforoperatoractions.'-'hih'datitbankcontainsHEPsobtainedfromapplicablereferences,su'chasReference22.The>HEPs:ar'etobe',hieanvaluesandavariancemayalsobeprovided.Toconvertthemedian'values-'in--the-'data-Qnk'ofReference22tomeanvalues,alognormaldistributionwasassumedusingtheerror-factor]fmesthemedianasthe95thpercentile.'the.Wflwp')iy:J.A;4'IPortionsofthisdatabankwerealsomadeavailabletoanalystsforcalculationofHEfui'lhhttiiayappearassimplebasiceventsinfaulttrees.P~b.IdentiTicationofOperatorActionSubtasksht'.t"c,r'.c.EstimationofPerformanceShapingFactors(PSF)~Is),'ifThistaskincludedthefollowingforthegenerationofacombinedPSFforeachspecificsubtas'k:Considerationofeachsubtaskseparatelywhilebeingserisitivetoitsplaceintheoverallschemeoftheoperatoraction.3-146 Identificationandconsiderationofcluesthatmayhelptheoperatorcarryoutthesubtask(includingwarninglightsandalarms).Identificationandconsiderationofconditionsthatmayimpedetheoperatorincarryingoutthetask.Identificationandconsiderationofdependenciesbetweentasks.(Table3.34liststheequationsusedtocalculateprobabilitiesconditionalonsuccessorfailureof,previoustask.)d.QuantificationofHEPsDefineinPRAThistaskinvolvedthecumulativequantificationoftheHEPsforeachhumanaction,usingthedatabank,'themodelsgeneratedfortheoperatoractions,theperformanceshapingfactorsidentified,andtheTHERPmethod.3DB2GenialAssumptionsItwasgenerallyassumedthattherewerenodependenciesbetweensubtaskswithinaparticularoperatoraction.However,ifastrongdependencybetweentasksdearlyexisted,suchcaseswereaccountedforindividually.Adetailedrevie~ofeachoperatoractionwasperformedtoensurethatdependencieswereappropriatelyaddressed.Formanyoperatoractions,step-bywtepproceduresareavailabletoguidetheoperatorduringanaccident.CreditfortheavailabilityoftheseprocedureswasprovidedintheselectionofappropriateHEPsfromtheHEPDataBank.Forotheroperatoractions,nodetailedproceduresareavailable,andonlygeneraldirectionisprovidedtotheoperator.Insuchcases,thesuccessoftheoperatoractiondependslargelyonthetrainingandmemoryoftheoperator,andthecalculatedHEPmay*beunreasonablyhigh.Interviewswiththeoperatorswereconductedtodetermineiftheoperatorshadtheknowledgeandtrainingtodealwiththesesituations.EstimatesofHEPsweremadebasedoninterviewswithoperatorsandreflecttheavailabilityofwrittenprocedures.)Significantimprovementshaveoccurredwithinthepastdecadepertaimngtoemergencyresponseprocedures.Theproceduresinplacetodayformostcommercialnuclearpowerplants(includingtheCook.NuclearPlant)aremoresymptomaticinnature.Unlessspeciflcdiagnosisdifficultieswerenoted,itwasassumedthattheEOPscurrentlyinplacefor,theCookNuclearPlantwereadequatetoaddressthetransientsymptomsandensurethattheoperatorprovidesthecorrectfunctionalresponse.DuetotheemphasisplacedonfollowingproceduresattheCookNuclearPlant,itwasassumedthatthefailureprobabilityfortheoperatortofailtoenterthereactortripprocedurefollowingtransientinitiationisstatisticallyinsignificant.TheHEPsusedinthesystemfaulttreesweregenerallycalculatedusinghandcalculations.TheHEPsusedineventtreesweregenerallycalculatedusingindividualfaulttrees.Table3.3-5summarizestheoperatorerrorsanalyzed,thefaulttreesutilized,andtheresultanthuman6@orprobabilitiesthatwerecalculated.3-147 1A'ABLE3.3-2HEPDATADIAGNOSISBYCONTROLROOMPERSONNELOFAN1Within10minutesofacompellingsignal2Within20minutesofacompellingsignal3Within30minutesofacompellingsignal4Within60minutesofacompellingsignal5Within1500minutesofacompellingsignalFAILUREOFADMINISTRATIVECONTROL2.7E412.7E422.7E438.5E448.5E454.3E-014.3E43.4,3E455.1E455.1E-07~HEPNEA~~VARIANECpABNORMALEVENT6Carryoutaplantpolicyorscheduledtaskssuchasperiodictestsormaintenanceperformedweekly,monthly,oratlongintervals7InitiateascheduledshiftlycheckingorinspectionfunctionUsewrittenoperationsproceduresunder:8normaloperatingconditions9abnormaloperatingconditions10Useavalvechangeorrestorationlist,,llUsewrittentestorcalibrationprocedures12*Usewrittenmaintenanceprocedures13'seachecklistproperlyERRORSOFOMISSION>1.6E-021.3E431.3E421.3E421.3E428.1E423.9E415.5E414.2E44,8.8E478.8E451.1E438.8E-051.0E421.1E41*5.8E42Whenprocedureswithcheckoffprovisionsarecorrectlyused(HEPperitemofinstruction):14ShortList,<10items15LongList,)10items1.3E433.8E438.8E477.9E463-148 TABLE3.3-2(Cont'd.)HEPDATA~HEPNEA~~VARIANEWhenprocedureswithoutcheckoffprovisionsareused,orwhencheckoffprovisionsareincorrectlyused(HEPperitemofinstruction):16Shortlist,<10items17Longlist,>10items18Whenwrittenproceduresareavailableandshouldbeusedbutarenotused3.8E-031.3E428.1E427.9E468.8E451.0E4219Sameasitem18,butisjudgedtobea"secondnature"1.6E424.2E44ERRORSOFCOMMISSIONSelectwrongcontrolfromanarrayofsimilar-appearingcontrols20212224identifiedbylabelsonlyfromafunctionallygroupedsetofcontrolsfromapanelwithdearlydrawnmimiclines'urncontrolinwrongdirection:whenthereisnoviolationofpopulationalstereotypeswhendesignviolatesastrongpopulationalstereotypeandoperatingconditionsarenormal3.SEE1.3E-031.3E431.3E438.1E427.9E468.8E471.1E451.1E451.0E4225whendesignviolatesastrongpopulationalstereotypeandoperationisunderhighstress5.5E415.8E4226Turnatwo-positionswitchinwrongdirection:noviolationofpopulationalstereotypes2.7&444.3E4727Setamultipositionselectorswitchtoanincorrectsetting(thiserrorisafunctionoftheclaritywithwhichindicatorpositioncanbedetermined:designsofswitchknobsandtheirpositionindicationsvarygreatly)2.7E434.3E453-149 TABLE3.3-2(Cont'd.)HEPDATAHEPDRIFFI~HEPIVIEAN}~VRIK~NE28Failuretocompletechangeofstateofacomponentifswitchmustbehelduntilchangeiscompleted3.8E437.9E4629Selectwrongcircuitbreakerinagroupofcircuitbreakers6.2E432.2E4530Improperlymateaconnector(thisincludesfailurestoseatconnectorscompletelyandfailuretotestlockingfeaturesofconnectorsforengagement)3.8E437.9E46CHECKERFAILSTODETECTERROR31Checkingroutinetasks,checkerusingwrittenmaterials(includesover-the-shoulderinspections,verifyingpositionoflocallyoperatedvalves,switches,circuitbreakers,connectors,etc.,andcheckingwrittenlists,tags,orproceduresforaccuracy)1.6E414.2E4232Sameasabovebutwithoutwrittenmaterials33Specialshort-term,onwf-a-kindcheckingwithalertingfactors3.2E418.1E421.7E411.0E-0234Checkingthatinvolvesactiveparticipation,suchasspecialmeasurements1.6E424.2E4435'iventhatthepositionofalocallyoperatedvalveischecked(item31above),checkingthatitiscompletelyopenedordosedafterbeingchangedorrestored5.5E415.8E4236~Checkingbyreader/checkerofthetaskperformerinatwo-manteam,orcheckingbyasecondchecker,routinetask(nocreditformorethan2checkers)5.5E415.8E-0237Checkingofstatusofequipmentifthatstatusaffectsone'ssafetywhenperforminghistasks1.6E434.2E4638AnoperatorcheckschangeorrestorationtasksperformedbyamaintainerDivideHEPinNo.37by23-150 TABLE3.3-2(Cont'd.)HEPDATAHEPMEAVARIANE~)FAILURETORESPONDTOONEOFMANYANNUNCIATORSALAIMINGCLOSELYINTIME391annunciatoralarming402annunciatorsalarming413annunciatorsalarming424,annunciatorsalarming435annunciatorsalarming446annunciatorsalarming457-10annunciatorsalarming46)10annunciatorsalarming2.7E441.6E-032.7E435.3E-038.0E431.3E421.3E413.6E414.3E471.6E454.3E451.7E-043.9FA41.1E431.1E411.3E41FAILURETORESPONDTOANANNUNCIATEDLEGENDLIGHT47Resumeattentiontoalegendlightwithin1minuteafteraninterruption(soundandblinkingcanceledbeforeinterruption)48Respondtoalegendlightifmorethan1minuteelapsesafteraninterruption(soundandblinkingcanceledbeforeinterruption)49Respondtoasteadywnlegendlightduringinitialaudit1.3E431.01.08.8E4750-Respondtoasteadywnlegendlightduringotherhourlyscans1.0ERRORSOFCOMMISSIONINREADINGANDRECORDINGQUANTITATIVEINFORMATIONFROMUNANNUNCIATEDDISPLAYS:51AnalogMeter52ChartRecorder3.SEE7.5E43Note:~=MedianHEPsareused,insteadofmeanvalues.3-151 TABLE3.3-3DESCRIPTIVEHRASCALINGGUIDES(ExtractedfromNUREG/CR-1278)~ActivitSTRESSLEVELAPPLICATIONExtremelyHigh(threatstress,e.g.,ATWS,StationBlackout,LossofIndicatorsduringLossof250VDC-earlyintransient)(conservativew.r.t.recommendedvalueof5)10TypicalTransient-Step-by-step,ModeratelyHighStress(conservativew.r.t.recommendedvalueof2-AssumesExperiencedOperatorsduringoff-normalconditions-Appropriatefordiagnosticactivitiesearlyinthetransient)TypicalTransient-LongerTimeFrameforResponse-Step-bywtep,ModeratelyHighStress-AppropriateforactivitiesperformedaftertheinitialdiagnosissincetherewouldbeexpectedtobeonlyalimitedamountofconfusioninthecontrolroomattheCook'uclearPlant2VeryLowTaskLoadOptimumStressLevel-foractivitiesperformedinanon-transientsituationwheretheoperatorisveryfamiliarwiththeactivityOTHERCOND1TIONSGeneralvalueforresponseforoperatorswhoarewell-trainedintheappropriateprocedures(thisalsoappliestothefailuretofollowproceduresonceentered).0.1MediumTimeFrameforResponseAbsenceofaDirectIndicatorofChangeAvailabilityofMultipleSupportiveIndicators0.10.13-152 TABLE3.3-3(Cont'd.)DESCRIFI'IVEHRASCALINGGUIDES~AviiviFailuretoEnterDetailedProceduresatCookNuclearHantbyFollowingtheInitialStepsofE4duetoEmphasisHacedonFollowingProcedures(appliestypicallytothediagnosisphaseofthetransient).0.01SelectionofWrongControlwhenaRelativelyLongTimeFrameisInvolved.1.0SelectionofWrongControlwhenControlsareVeryClearlyMarkedwithMimicLines0.1SpecialValueforCaseswheretheOperatorisEspeciallyWell-TrainedinaSpecificDiagnosis-AttheCookNuclearPlanttheoperatorsareespeciallywell-trainedonentranceintotheEOPs(e.g.,SteamGeneratorTubeRupture)0.01MemorizedProcedure0.13-153 TABLE3.34DEPENDENCELEVELDEFINITIONSEquationsforconditionalprobabilitiesofsuccessandfailureonTask>>N",givensuccessorfailureonpreviousTask>>N-1",fordifferentlevelsofdependenceLevelofDependenceDEPSuccessEquationsFailureEquations1=ZD2=LD5=CDPr[F>>N>>S>>N1>>ZD]=1>>Nn>>N-1>>LD]=19Q/20Pr[F>>N>>S>>NInMD]=6Q/7fnNnnN1n]=QPr[F>>N>>S>>N1>>CD]=ooPr[F>>N>>S>>N1>>D]=QPr[FNnSnN1>>LD]=(1+19Q)/20[FnNnSnN1nMDl=(1+6Q)/7Pr[FnNnSnN1nHD]=(1+Q)/2Pr[F>>N>>S>>N1>>CD]=1'0ZDLDCDPr[F>>N>>S>>N-1>>ZD]ZeroDependence(independent)LowDependenceMediumDependenceHighDependenceCompleteDependenceProbabilityoffailureinsubtaskNgivensuccessinsubtaskN-l,withazerodependencebetweenthetwosubtasks.IstheHEPmodifiedbythePSF,otherthandependence.3-154 TABLE3.3-5SUMMARYOFHUMANERRORPROBABILITIES0eratorActionofEvenTreeNdeManualValveRestorationAfterT&MAirorMotor-OperatedValveRestorationAfterT&MTimeAvailahleN/AN/AUedinEventTreeHEP(withouthardwarfailures2.1E-054.2E-07Dependencies/~NotContainmentIsolationEnergizeHzIgnitersAlignBatteryChargerSupplyAdditionalWatertoAFWMispositionTDAFWPFanSwitchReopenAFWValvestoS/GIsolateMCM-221IsolateS/GSwitchovertoHPRecirculationSwitchovertoCSorLPRecirculationAlignESWtoAFWCloseCBsforAlternate69kVBusN/AN/AN/AN/AN/AN/AN/AN/A30min20min45minN/A6.50E441.32E443.34E-055.20E453.04E-065.20E454.23E465.23E-066.31E-065.31E-056.31E-066.54E443-155 TABLE3.3-5(Cont'd.)SUMMARYOFHUMANERRORPROBABILITIESratrActionofEventTreeNdeCloseOutputCB/SwitchinSwitchyardOpenOutputCBK&K1StripEmergencyBusesRestoreControlAirinLOOPPlaceStandbyPlantAirCompressorintoServiceTimeAvailableN/AN/AN/A10min10minU.edinEventTreeHEP(withouthardwarfailur6.50E436.54E446.51E431.08E-031.08E43Dependencies/~otAssureContainmentDrainOperabilityRestoreCCWWithinOneHourRestoreCCWWithinEightHoursRestoreESWWithinOneHourRestoreESWWithinEightHoursTripRCPsDuringLossofCCW/ESWTDAFWPRoomDoorLeftClosedOLI-DepressurizationtoAllowLowPressureInjectionN/A60min60min8hrsN/AN/A20minCCWCCWCCW,ESWMLO3.38E-071.30E436.62E43L30E426.52E431.30E421.05E-041.51E-01LPI,PORVP,SGPORV,AF4PBF-PrimaryBleedandFeed30minSLO,SLB,LSP,TRA,3.37E-05TRS,SGR,25A,SBO3-156HP2,PORVP eratrActionofEventTrNdeOA5-SteamGeneratorDepressurizationandCondensateFeedTABLE3.3-5(Cont'd.)SUMMARYOFHUMANERRORPROBABILITIESedinEventTr30minHEP(withouthardwafailur3.06E45Dependencies/~Nt13CONDOA1-CooldownandDepressurizeRCSandTerminateSafetylqjectionBeforetheRupturedS/GFillsOA2-CooldownandDepressurizetheRCSandTerminateSafetyhjectionAftertheRupturedS/GFillsOA3-ProvideLong-TermCooldownandRCSDepressurizationXHR-RecoveryofACPowerforStationBlackout30min60min10-20hrs1-8hrsSGRSGRSGRSBO1.05E-043.55E-022.11E443.05E-0213PORV13PORVLPR,13PORVRCD-RCSCooldownforStationBlackoutRRI-RestorationofRCSInventoryMF1-InitiationofMainFeedwaterMRI-ManualRodInsertionPP1,PP2-PrimaryPressureReliefLTS-Long-TermShutdown60min60min30min1minN/AN/ASBO,CCW,ESWSBO,CCW,ESWTRAATWATWATW6.99E446.80E-041.63E-041.37E-03L46E431.35E43SGPORVPORVP,HP4,HPI12FEEDHPS3-157 TABLE3.3-5(Cont'd.)SUMMARYOFHUMANERRORPROBABILITIES0eratorActionofEventTreeNdeOIB-IsolationofRHRPumpSealLOCAOA6-Post-LOCASecondary4ideCooldown2AV-Unit2AFWCrosstieRCE-RCSCooldownwithRWSTConservationTimeAvailahleN/A30min10minedinEventTreeISLSLO,MLOISLHEP(withouthardwarefailur5.40E426.23E-042.08E441.08E-03Dependencies/~NtSGPORV,AF42AFSGPORV,13PORV3-158 39.4CommonCauseFailureDataCommoncausefailure(CCRwasusedtodescribeeventsthatrepresentasubsetofdependentfailureswheretwoormorecomponentsfailduetothesamecauseatthesametime,orinashortinterval,andthatareadirectresultofasharedcause.Thecommoncausefailureanalysisevaluatedandestimatedtheeffectsofthesedependenciesthatimpactthecapabilityofasystemtopreventormitigateasevereaccident.0;ToassurethattheeffectsofcommoncausewereproperlyaddressedintheCookNuclearPlantanalysis,commoncausefailuresweremodelledatthesystemlevelinthefaulttrees.TheMultipleGreekLetter(MGL)methodwasusedforquantifyingcommoncausefailures.TheCookNuclearPlantIPEusedtheMGLmethodandparametricfactors(beta,gamma,anddelta)asdefinedinReference30asfollows:~BETAconditionalprobability(Pr(x>2)x>1))thatthecommoncauseofacomponentfailurewillbesharedbyoneormoreadditionalcomponents~GAMMAconditionalprobability(Pr(x>3(x>2))thatthecommoncauseofacomponentfailurethatissharedbyoneormorecomponentswillbesharedbytwoormorecomponentsadditionaltothefirst~DELTAconditionalprobability(Pr(x>4]x>3))thatthecommoncauseofacomponentfailurethatissharedbytwoormorecomponentswillbesharedbythreeormorecomponentsadditionaltothefirst1.2.3.4,IdentifyCCFgroupsPlaceCCFsinthesystemfaulttreesCalculateCCFvaluesQuantifyCCFswiththesystemfaulttreefailuresTheCCFanalysistookthefollowingapproachforeachmodelledsystem:0)Note:HumanerrorwasaddressedseparatelyintheIPEprocessandwasnotincludedincommoncausefailurecalculations.TheevaluationoftheCookNuclearPlantcomponentfailuredataindicatedthattherehadbeennocommoncauseeventsattheCookNuclearHantapplicabletocurrentmaintenanceandoperationpractices.Asaresult,agenericCCFdatabaseofcommoncauseeventswasdevelopedusingReference7.ThegenerationofthegenericCCFdatabasewaspreparedusingReference35.ThespecificMGLfactorsresultingfromthisanalysisareincludedinTable3.34.Table3.34isnotacomprehensivelistingofMGLfactorsforallcomponents.Thus,anaveragecommoncausecompon'entgroup,theALLrowinTable3.34,wasquantifiedfromacompositeofallthecommoncausefailuresforallcomponentsinthedatabase.TheALLMGLfactorswereappliedtocomponentswhichhavenohistoryofcommoncausefailure,butwerejudgedbythesystemanalysttohaveapotentialforcommoncausefailure.Asanexample,airoperatedvalves(AOVs)donotappearinTable3.34,therefore,theALLMGLfactorswouldapplytotheAOVsinasystemwheretheAOVsaregroupedintoacommoncausefailuregroup.Ingeneral,thecomponentsfromthedatabasewerejudgedtobemorecomplexandmoresusceptibletocommoncausefailuresthanthosecomponentswhichwouldemploytheALLMGLfactors.TheALLMGLfactorsare,therefore,conservative.UseofthegenericCCFdatabaseintheCookNuclearHantIPEwasjudgedtobeconservative.FurtherexaminationwasrequiredonlyforthoseCCFeventswhichappearedtobedominatingthecoredamage3-159 frequency.ForthoseCCFeventswhichdominatedcoredamage,expertjudgmentwasusedtoverifythatthecommoncauseevent'sapplicabilitytoCookNuclearPlantwaseitherappropriateorconservative.3-160 TABLE39-6COOKNUCLEARPLANTIPEMGLCOMMONCAUSEFACTORS0)ReactorTripBreakersDieselGeneratorsMotorOperatorValvesSafetyReliefValvesCheckValvesPumpsHighHeadResidualHeatRemovalContainmentBuildingSprayAuxiliaryFeedwaterServiceWaterandComponentCoolingWaterChillersFans0.160.0250.0380.0940.060.100.0770.0570.0210.0320.110.13Gamma0.400.150.230.660.330.280.150.240.200.630,330.330.610.250.690.660.520.190.43-a-0.520.840.520.52All0.080.330.52'verageofallcomponentfailures.a-Valueoffactorisnotcalculated.Avalueequaltothevaluefortheaverageofallcomponentfailures(All)isusedforthegenericMGLscreeningmethod,thatis,delta=.52Oj3-161 32.5QantifiadionofVnavaBabBityofSystemsandBmctionsThefaulttreeswhichmodelledplantsystemsandoperatoractions(suchasprimaryplantbleedandfeed)wereconstructedandquantifiedusingthe'RAFTERcodesystem(Reference10).TheFaultTreeAnalysisGuidelinesforCookNuclearPlant(Reference48)providedguidanceforfaulttreeconstruction.PlantsystemsaredescribedinSection3.2.SupportingdescriptionsfortheoperatoractionsfaulttreesarefoundinSection3.3.3andintheHumanReliabilityAnalysisNotebook(Reference15).Table3.3-7isalistoffaulttree/eventtreeheadingprobabilitieswhichincludesthesystemandfunctionunavailabilities.ThesevaluesincludecommoncausefailuresthatwerediscussedinSection3.3.4.NotethattheunavailabilitieslistedinTable3.3-7werequantifiedassumingthatallsupportsystemswereavailable(i.e.-supportsystemfailurevalueswerenotincludedwithinTable3.3-7values.)Supportsystemunavailabilitieswereaccountedforinthequantificationoftheinitiatingeventaccidentsequences(Section3.3.6).3-162 TABLE39-7UNAVAILABILITYOFSYSrXMSANDFUNCTIONSAFlAFSAFI'FHAF2AF3AFCAF42AFCSICSRCCWECCWWCCWELCCWWLESWEESWWESWELESWWLNESW1NESW2CONAIR1CONAIRLSCONAIR2CONAIR2LCONAIR3CONAIR3LCONAIR4CONAIR4LCONAIR5CONAIR5LACCLPILPR6.69E451.22E-035.79E427.60E446.88E454.60E445.72E436,69E452.43E441.48E-047.75E-048.89E453.12E431.35E443.17E432.18E456.89E-039.79E458.10E431.18E-042.79E446.27E441.55E422AOE433.96K@32.23E-042.23E-042.23E-042.23E442.23E-042.23E446.00E-043.09E-048.47E-04HPIHPRT11A/T11DT11B/T11CT11AP/T11DPT11BP/T11CP11A/11D11B/11C11AZ/11DZ11BZ/11CZ1AB/ICDDCBDCADCNDCNSBOCRID1/2/3/4120AFWELSC12FEED13COND13CONDMFMSISSVSGISGPORVPORVPPZRSAFEPZRSAFE113PORVCF3.56E-051.20E435.16FA49.83E-041.26E-032.34E452.34E451.33E-041.32E-043.20E462.97E-066.61E-054.21E-051.82E426.22E453.29E-043.42E-05'1.61E452,81E461.23E-031.23E431.17E425.43E444.54E-043.68E-049.68E-02248E-035.62E-058.05E-041.79E421.11E431.93E445.45E441.37FA43-163 32.6QuantificationofSequence$hxpwmciesTheIPEProjectusedaPCbased(IBMPS/2)PRAsoftwarecode(WLINKcodesystem,Reference46)toquantifytheinitiatingeventaccidentsequences.TheeventtreesdescribedinSection3.1providedthestructureforpropagationoftheinitiatingeventsequences.Usingafaulttreelinkingprocess,theWLINKcode(Reference46)linkedallnecessarysupportsystemfaulttreesintoeacheventtreetopeventnode.Afterwards,theWLINKcode(Reference46)quantiTiedeachinitiatingeventaccidentsequence.Thisyieldedaccidentsequencefrequenciesanddominantaccidenteventcutsets.Theseoutputswerethenusedinyetanotherquantificationwhichproducedanoverallcoredamagefrequencyvalue(internalevents)andoveralldominantcontributorstocoredamagefrequency.TheseresultsareexplainedinSection3.4.32.7InternalfloodingAnalysisThissectionsummarizesthemethodologyandresultsoftheinternalfloodingevaluation.39.7.1InformationAssemblyThefollowinginformationwasassembledandtabulatedintheCookNuclearHantInternalFloodingAnalysisNotebook:1.FloodZonesThefloodzoneswerechosentocorrespondtotheexistingfirezonesdevelopedforanalysisofcompliancewith10CFR50AppendixRrequirements.Ingeneral,barriersseparatingAppendixRzoneswerefoundtobeapplicabletotheinternalfloodinganalysis.ThoseAppendixRzonesboundedbyanythingotherthanactualbarrierswereanalyzedonacase-by~basisforfloodingapplicability.2.SourcesofFloodingandSprayingSourcesoffloodingandsprayingandthelocationofthepipingassociatedwiththesesourceswereidentified.3.LocationofComponentsCriticaltoOperationorSafeShutdownComponentsandtheirlocationsthatwereconsideredcriticaltooperationorsafeshutdownwereidentified.4.DescriptionofFloodandSprayEventsForeachfloodzone,floodingandwatersprayeffectsoncomponentsandequipmentweredescribed.32.72hoorAssumptionsThefollowingmajorassumptionsweremadeduringtheanalysis:1.Equipmentwithinazonethatissubjecttoafloodingorsprayeventisdisabled.2,ContainmentfloodingduetoaLOCAorhighenergylinebreakswasdeterminednottobeaconcernsincethisisaconsiderationintheplantsdesignbasis.Asaresult,containmentfloodingwasnotreviewedinthisfloodinganalysis.3.Low-andmedium~ergyinsulatedpipeswereassumedtodripifaleakdeveloped(i.e.,theyare3-164 notaspraysource).Barepipeswereassumedtobespraysourcesfora10footlin~f-sightradius.~)4.Lineswhichwerenotnormallyfilledwithliquid(i.e.,drainlinesanddryfireprotectionpiping)werenotconsideredtobecrediblefloodingorspraysources.3B.7BMethodologyThemethodologyusedforthefloodinganalysiscanbesummarizedasfollows:1.Possibleflood-inducedinitiatingeventswereidentifiedand,forthepurposesofthisanalysis,includeonlyatransientwithoutpowerconversionsystemsavailable.2.AqualitativescreeningwasperformedusinginternalAEPSCcalculationstoidentifythesignificantfloodingevents.Thecapabilityofafloodingeventleadingtoatransienteventandthepossibilityofdisablingsafeshutdowncomponentsasaresultofthefloodwerethetwofactorsconsideredassigniiflicantduringthescreeninganalysis.Ifthetotallossofcomponentswithinafioodzonewouldnotinitiateatransient,orifnosafeshutdownequipmentwouldbeaffected,thenthefloodzonewasremovedfromfurtheranalysis.3.Quantitativeanalyseswereperformedforthoseareasidentifiedassignificant.Forquantitativeanalysis,thefollowingcalculationofinitiatingeventfrequencywasmade:Forfloodingintheturbinehall,aworstcasefloodwouldresultfromanESWdischargelinebreak.Thefrequencyofthiseventwasconservativelycalculatedusingtheprobabilityofamaincondenserexpansionjointfailure.Theinitiatingeventfrequencywascalculatedasfollows:Cond=CondenserEJ=ExpansionJoint,>~2'-4x6condx2-failuresEJEJ-yrcond=3.0E-3/yr~Note:ThefailurerateforthecondenserexpansionjointisfromReference67.32.7.4ResultsTheonlysignificantfloodingscenariofoundwasanESWdischargelinebreakcausingafloodoftheturbinebuildingsub-basement.ThisfloodispostulatedtodisabletheNESWpumps,whichinturncausefailureoftheplantandcontrolaircompressors.ThetransientwithsteamconversionsystemsunavailableeventtreewasquantiTiedforthisscenarioandyieldedacoremeltcontributionof2.00E47/year.3-165 3.4ResultsandSmxningProcess3.4.1AppiicatioaofGaxxicLetterScneaingCriteriaFollowingtheguidanceprovidedinNUREG-1335,thefollowingscreeningcriteriawereutilizedtodeterminepotentiallyimportantsystemicsequencesandsystemfailures.1.Anysystemicsequencethatcontributes1.00E4)7ormoreperreactoryeartocoredamage.2.Allsystemicsequenceswithintheupper95%ofthetotalcoredamagefrequency.3.Allsystemicsequenceswithintheupper95%ofthetotalcontainmentfailurefrequency.4.Systemicsequencesthatcontributetoacontainmentbypassfrequencyinexcessof1.00E48perreactoryear.Table3.4-1providesalistingofeachinitiatingaccidentevent,theCDFvalue,theinitiatingeventfrequencyandpercentcontributiontoCDF.ThetotalcoredamagefrequencyatCookNuclearPlantis6.26E-5.Table3.4-2providestheimportantsystemicsequences,descriptionsofsequenceprogression,majorcontributorstosequencefailureandmajoroperatoractions.Thesequencesinthistablearegroupedbyaccidentevent,startingfromthemostdominantaccident(smallLOCA)totheleast(interfacingsystemsLOCAorV-sequenceLOCA).AsnotedintheSection3.1,containmentsystems(containmentspray,hydrogenignitersandcontainmentairrecirculationandhydrogenskimmersystems)weremodelledwithintheaccidentsequences.Toaccountforcoredamage,therefore,eachsequencewithintheeventtreeswastracedbackwardstothepointwereactualcoredamageoccurred.Thebeginningofthesequencetothispointwasdefinedasa"systemicsequence".SummingthefailurevaluesthatbranchedoutfromthispointgavethesequencefailurevaluesshowninTable34-2.Thefirst100sequencesfromtheaccidentsequencequantification,whichprovidedinputtoTable3.4-2,areshowninTable3.4-3.Eachsequence'cutsetshowninTable3.4-3liststhesequencefailureprobabilityvalue,theaccidenteventthatinitiatedthesequence(IEV-xxx),thesequenceprogression(SUC-xxxindicatesthattopeventxxxwassuccessful)andthecomponent/eventidentifierwhichidentifiesthecomponent/eventthatfailedthesequence.AnimportancerankingofthedominantcontributorstoCDFisfoundinTable3.4-4.EachcontributorinTable3.44islistedbyits'omponent/eventidentifier,itsoverallimportancetoCDF,numberofsequencecutsetstheidentifierappearedin,its'verallcontributiontoCDF(derivedfromitsimportancetoCDFandidentifierplacementwithinthelogictrees)andthefailureprobabilityvalueoftheidentifierbyitself.Contributorsthatbeginwith"SUC-"indicatesuccessoftheseparticulareventtreetopnodes(successthatoccurredmostoften)anddonotindicatefailureofanykind.Contributorsthatbeginwith"IEV-"aredirectlylinkedtoaccidentevents(e.g.IEV-SLOindicatesthatthesmallLOCAeventwasthemostsignificantaccidentwitha47.3%contributiontoCDF,anaccidentCDFvalueof2.963E-5andasmallLOCAinitiatingeventfrequencyof6.SOE-3.)3-166 TABLE3.4-1ACIDENTEVENTMMARV~AccIdeeSLOSGRMLOATW~SBOLLOSWSSLBTRALSPISLCoreDamage~Vaiu2.96E4513SE457.07E46431E462$5E461,13E469$2E476.04E476.04E475.69E473.00E472.S6E472$3E471.73E47538E48InitiatingEvent~Fre~unp6$0E438.71E44720E439.17E444,67E451.40E453,00E443.73E451.16E42330E443.00E47380120E41,4.00E426.70E47Wonriuin22.11136,94.60.960.960.910.480,460.450280.083-167 TABLE3,4-2SUMMARYOFSIGNIFICANTSEQUENCESKEYACC-AccumulatorsAF1,AF4-AuxiliaryFeedwaterActuationAF2-AuxiliaryFeedwatertointactSteamGenerator(s)AF3-AuxiliaryFeedwatertofaultedSteamGeneratorAFC-AuxiliaryFeedwaterContinuesAFH-Halfflow-900GPMAux.FeedwaterflowAFS-AuxiliaryFeedwaterActuationwithSteamLineBreakAFT-Turbine-DrivenAuxiliaryFeedwaterflow2AV-Op.ActiontoprovideUnit2AFWflowAMS-ATWSMitigationSystemActuationCircuitryBRH-ResidualHeatRemovalSystemBreachCF-ContainmentRecirculationFansCH1-ComponentCoolingWaterSystemrestoredw/in1hourCH8-ComponentCoolingWaterSystemrestoredw/in8hoursCNU-ReactorcorenotuncoveredCSI-ContainmentSprayInjectionCSR-ContainmentSprayRecirculationEH1-EssentialServiceWaterSystemrestoredw/in1hour3-168 TABLE3.4-2(Cont'd.)SUMMARYOFSIGNIFICANTSEQUENCESKEYnt'EH8-EssentialServiceWaterSystemrestoredw/in8hoursHI-HydrogenIgnitersHPI,HP2,HP3-EmergencyCoreCoolingSystem(HighPressure)InjectionHPR-EmergencyCoreCoolingSystem(HighPressure)RecirculationLPI-ResidualHeatRemoval(LowPressure)InjectionLPR-ResidualHeatRemoval(LowPressure)InjectionLTS-LongTermShutdownMF1-MainFeedwaterMS1-SecondarySideIsolationOA1-DepressurizeandCooldownPrimarySideBeforeFillingOA2-DepressurizeandCooldownPrimarySideAfterFillingOA3-CooldownandDepressurlzePrimarySidePerECA-3.1/32(Subcooled/Saturated)OA5-Op.ActiontoDepressurizeaSteamGeneratorOA6-PrimaryCooldownUsingAFWandSteamDumpOIB-Op.ActiontoIsolateResidualHeatRemovalLOCAOLI-DepressurizePrimaryandInitiateLowPressureInjectionSGI-SteamGeneratorIsolationbyMainSteamIsolationValveClosureSSV-IntegrityMaintainedorRestoredinSteamGenerator3-169 TABLE3.4-2(Cont'd.)SUMMARYOFSIGNIFICANTSEQUENCESKEYcont'dPBF-PrimarySideBleedandFeedPPR-PrimarySidePressureReductionRCD-ReactorCoolantSystem(PrimarySide)CooldownRCE-ReactorCoolantSystemCooldownandRefuelWaterStorageTankConservationRCP-ReactorCoolantPumpsTrippedRPL-ReducedPowerLevel(lessthan409o)RRI-RestoreReactorCoolantSystemInventoryRVC-ResidualHeatRemovalReliefValveClosureXHR-ACPowerRestorationInXHoursMa'ntributoAFW=AuxiliaryFeedwaterCC=CommonCause(CommonMode)FailuresCST=CondensateStorageTankCTS=ContainmentSpraySystemECCS=EmergencyCoreCoolingSystem(HighPressure)ESF=EngineeredSafetyFeatures(ReactorProtection)MOV=MotorOperatedValve3-170 TABLE3.4-2(Cont'd.)SUA&fARYOFSIGNIFICANTSEQUENCESe>KEYcont'dMorCntriutorsont'd.MSIV=MainSteamIsolationValveOE=OperatorErrorPORV=PowerOperatedReliefValveRHR=ResidualHeatRemovalSI=SafetyInjection(partofECCS)Note;Anasterisk(*)byasequenceindicatesthatthesequenceiswithintheupper95%ofCDFTheaccidenteventsarepresentedinorderofimportance.ThevalueswithintheparenthesisbesideeachEVENTareasfollows:eventcoredamagevalue,initiatingeventfrequency,eventimportancecontributiontoCDF.TheTable3,4-2columnsaredescribedasfollows:SequenceFailureProbability-sequencefailurevalue(Section3.4.1describeshowvaluewasderived).SequenceProgression-accidentsequenceprogressionupthroughcoredamageFailureArea(s)-Point(s)insequencewheresystem/operatorfailureoccurredMajorContributors-majoritemsthatfailedtheFailureArea(s)OperatorActions-eventtreetopeventoperatoractions(ex,OA3)andoperatoractionsfoundwithintheplantsystemtopevents(ex.HPR)3-171 SequenceFailure~ProbabttttSequence~ProrasslonFailure~AranTABLE3.4-2(Cont'd.)SUMMARYOFSIGNIFICANTSEQUENCESMajor~onlrlbntoOperator~AtionEVENT:SmallLOCA-SLO(2.96E45-6$0FA3-473%)TopEvents:SLO-HP2-OA6-PBFZSI-HPR-CSR-HI-CF~135OE45~L173E454379E46SLO-HP2-OA6-CSI-HPR-SLO-HP2SLO-HP24A6-PBFCSI,HPROA6,PBF-CCECCSrecirculation-SIpumpsfail-CCESFrelays-SIpumplailure-RHRpumpfailure-valvemaintenance-ESWpumpmaintenance-ECCS/RHRpumptrainmaintenance-CCECCSInjection@1pumpslail-CCESFsignalfail-CCESFrelays-CCbothESFtrains-checkvalvefailure-plantaircompressorsfail-CCcompressedAirSystem-valvefailure-compressedairsafetyvalvefailureOA6,OEswitchtocoldlegrecirculation(HPR)NoneOA6,PBF3-172 SequenceFailure~ProbabiiirSequence~ProressioFailure~AreaTABLE3.4-2(Cont'd.)SUMMARYOFSIGNIFICANTSEQUENCESMajorcontributorsOperatorActionsEVENT:LossComponentCoolingWater-CCW(138E45-8.71E44-22.18o)TopEvents:CCW-RCP-AFl-MF1-CH1-RCD-CH8-CNU-RRI-CSI-HPR-CSR-HI-CF~1.13E451.626K@68.643E47CCW-RCPCCW-RCP-AF1-CH1-RRICSI-HPRCCW-RCP-AF1-CH1-RRIRCPHPRRCP-CCECCSrecirculation-SIpumpsfail-OEdiagnoseRCScoolingneeds-CCESFsignal-CCbothESFtrainsRCPRCP,CH1,RRI,OEalignCSTbackupwatersupply(AF1),OEswitchtocoldlegrecirculation(HPR)RCP,CH1,RRI,OEalignCSTbackupwatersupply(AF1)

SequenceFailure~PrababttttSequence~PrarealaaFailure~AreaeTABLE3.4-2(Cont'd.)SUMMARYOFSIGNIFICANTSEQUENCESMoor~CnntributoOperatorActionsEVENT:SteamGeneratorTubeRupture-SGR(7.07E46-720E43-113%)TopEvent:SGR-AF2-AF3-HPI-SGI-OAl-SSV-OA2-OA3-PBF-CSI-HPR-CSR-HI-CF5.995E466598E472503E471.194E473.440E48SGR-AF2-HPI-SGI-OA14SV-OA2SGR-AF2-HPI-SGI-OAINSV-OA3SGR-AF2-AF3-HPISGR-AF2-HPI-SGI-OA3SGR-AF2-HPI-SGIOA1,OA2OAl,SSV,OA3AF2,AF3,HPISGI,OA3HPI,SGI-Plantaircompressorsfail-CCcompressedair(85psireduces)-CCcompressedAirSystem-valvefailure-CCstmGen.PORVs-Plantaircompressorsfail(OA1,OA3)-faultedsteamgeneratorsafetyvalvesfailtoreseat-Turb.drivenAFWpumpfailure(AF2,AF3)-ESFsignalfailure(HPI)-CC250VDCfuses-MSIVfailuretoisolate(SGI)-regulatorfailuretoPressurizerPORVs(OA3)-Plantaircompressorfailure(OA3)-CCRHRpumpfailure-CC250VDCfuses-CCESFsignal(HPI)-MSIVfailuretoisolate(SGI)OA1,OA2,OEalignCSTbackupwatersupply(AF2),OErecognizeeventandisolatestmGen.(SGI)OA1,OA3,OErecognizeeventandisolatestmgen(SGI)OEalignCSTbackupwatersupply(AF2)OA3,OEalignCSTbackupwatersupply(AF2),OErecognizeeventandisolatestm.gen.(SGI)OEalignCSTbackupwatersupply,OErecognizeeventandisolatestmgen(SGI)3-174 SequenceFailure~ProhahiiiiSequence~ProressionFailure~AreasTABLE3.4-2(Cont'd.)SUMMARYOFSIGNIFICANTSEQUENCESMajorgonlrihu(orsOperatorActioiisEVENT:MediumLOCAMLO(4.31E-06-9.17E-04-6.9%)TopEvent:MLO-ACC-HP2-OA6-OLI-CSI-HPR-LRP-CSR-HI-CF1.802E-061.493E-065.490E-072.541E-072.192E47MLO-ACC-HP2-OA6-CSI-HPRMLO-ACC-HP2-OA6MLO-ACCMLO-ACC-HP2-OLIMLO-ACC-HP2-OLI-CSI-LPRCSI,HPROA6ACCHP2,OLIHP2,LPR-CCECCSrecirculation-Slpumpsfail-CCESFrelays(CSI,HPR)-OEdiagnosecooldownneed-Plantaircompressorsfail-CCcompressedairsystem-compressedairsafetyvalvefailure-Accumulatorcheckvalvefailure-CCECCSinjection-SIpumpsfail(HP2)-OEfailuretodiagnosedepressurizationneed(OLI)-CCESFsignal(HP2)-checkvalvefailure(HP2)-CCESFsignal(HP2,LPR)-ESFsignalfailure-bothtrains(HP2,LPR)OA6,OEswitchtocoldlegrecirculation(HPR)OA6NoneOLIOLI,OEswitchtocoldlegrecirculation(LPR)

SequenceFailure~ProhahiliiSequence~ProressioaFailure~AreasTABLE3.4-2(Cont'd.)SUMMARYOFSIGNIFICANTSEQUENCESMajorContributorsOperatorActionsEVENT:AnticipatedTransientWithoutScram-ATW(2.85IE46-4.67E-05-4.6%)TopEvent:ATW-RPIMRI-AMS-AFI-AFH-PPR-LTS-CSI-CSR-HI-CF2.308E-063.910E-07ATW-RPL-MRI-AMS-AFH-PPRATW-RPL-MRI-AMSRPL,PPRRPL,AMS-ReactorPower>40%(RPL)-Pressurereliefinadequateearlyinfuelcyde-ReactorPower>40%(RPL)-ATWSmitigationsystemfailedMRI,PPR,OEalignCSTbackupwatersupply(AFII)MRIEVENT:StationBlackout-SBO(1.132E-06-1AOE-OS-1.8%)TOPEVENTS:SBO-AIT-RCD-AFC-XHR-CNU-RRI-AFI-PBF-CSI-HPR-CSR-HI-CF4.050E-075.779E-07SBO-AFl'-RCD-AFC-XH1-CNUSBO-AFI'-RCD-AFC-XH1CNUworeuncovered-Failuretorestoreelectricalpower(XH1)RCD,XH1RCD,XII13-176 SequenceFailure~Prol>abilitSequence~ProresionFailure~AreaaTABLE3.4-2(Cont'd.)SUMMARYOFSIGNIFICANTSEQUENCESMajor~onfribators'peratorActionsEVENT:LargeLOCA-LLO(9523847-3.00E44-Idaho)TOPEVENTS:LLO-ACC-LPI-CSI-LPR-CSR-HI-CF3.031E-072.941E471.794E47LLO-ACC-LPI-CSI-LPR-CSRLLO-ACC-LPI-CSI-LPRLLO-ACCCSRLPRACC-CC-CSTsystem(CTSpumpfailure)-CCESFrelays-OE-switchCTStorecirculation-CC-RIIRrecirculation(RHRpumpfailure)-RHRpumpfailure(injectionandrecirculation)-CCESFrelays-OEswitchRHRtorecirculation-AccumulatorcheckvalvefailureOEswitchtocoldlegrecirculation(LPR);OEswitchCTStorecirculation(CSR)OEswitchtocoldlegrecirculation(LPR)None1.754E47LLO-ACC-LPILPI-CCESFrelays-CCESFsignal-ESFsignalunavailable-bothtrains-RHRcheckvalvefailure-CCRHRinjection(RHRpumpfailure)None SequenceFailure~prahabiiirSequenceProi~res.briinnFailure~AreaaTABLE3.4-2(Cont'd.)SUMMARYOFSIGNIFICANTSEQUENCESMajor~aarriharaOperatorActionsEVENT:LossofEssentialServiceWater-SWS(6.04E47-3.73E45-0.969o)TOPEVENTS:SWS-RCP-AF1-MF1-EH1-RCD-EHS-CNU-RRI-CSI-HPR-CSR-HI-CF4$43E47SWS-RCPRCPRCPRCPEVENT:Lossof250VACPower-VDC(6.04E47-L16E42-0.96%)TOPEVENT:VAC-AF1-2AV-CSI-CSR-HI-CF6.037E47VDC-AF1-2AVAF1,2AV-OEalignCSTbackupwatersupply2AV,OEalignCSTbackupwatersupply(AF1)3-178 SequenceFailure~Prob<bi<itSequence~Proree~sinFailure~AreaaTABLE3.4-2(Cont'd.)SUMMARYOFSIGNIFICANTSEQUENCESMajor~ContributoOperator~A<tineEVENT:SteamLineBreak@LB(5.69E47-330E44-0.91')TOPEVENT:SLB-HP3-MS1-AFS-PBF-CSI-HPR-CSR-HI-CF3.146E472399E-07SLB-HP3SLB-IIP3-MS1HP3MS1-CCECCSinjection(MOVfailure)-CCESFsignal-CCESFrelays-ESFsignalunavailable-bothtrains-ECCScheckvalvefailure-CCMainSteam(MSIVsfailtoshut)-CCESFrelays-CCESFsignal-ESFsignalunavailable-bothtrainsNoneNoneEVENT:ReactorVesselFailure-VEF(3.00E47-3.00E47-0.48Vo)TOPEVENT:VEF-CSI-CSR-HI-CF2.995E-07VEFNone SequenceFailure~ProbsbilirSequenceProgre~sionFailure~AressTABLE3.4-2(Cont'd.)SUMMARYOFSIGNIFICANTSEQUENCESMailor~onrribnroOperator~AriesEVENT:TransientswithSteamConversionAvailable-TRA(2$6E47-350-0.46%)TOPEVENT:TRA-AFI-OA5-MFl-PBF-CSI-HPR-CSR-HI-CF2J57E47TRA-AF1-OA5-MF1-PBFAFl,OA5,MF1,PBF-OE-alignCSTbackupwatersupply(AFI,OA5)-Plantaircornpressorsl'ail(MFI,PBF)-CCcompressedairsystem(MFl,PBF)-Compressedairsafetyvalvefailure(MF1,PBF)-DCpowerventfanfailure-DCpowerfusefailureOA5,MFI,PBF,OEalignCSTbackupwatersupply(AF1)EVENT:TransientsWithoutSteamConversionAvailable-TRS(2$3FA7-120E41-0.45%)TOPEVENTS:TRS-AF1-PBF-CSI-HPR-CSR-HI-CF2.647E47TRS-AF1-PBFAF1,PBF-AFWturb.drivenpumpfailure(AF1)-CC4KVpowerventilationfailure-CC250VDCpower-OE-alignCSTbackupwatersupply-Airpressureregulatorfailure(PBF)PBF,OEalignCSTbackupwatersupply(AF1)3-180 SequenceFailure~probabiiieSequence~ProresionFailure~AreasTABLE3.4-2(Cont'd.)SUMMARYOFSIGNIFICANTSEQUENCESMoorContributorsOperator~AeiionEVENT:LossOffsitePower-LSP(1.73E47-4.00E42-0287o)TOPEVENT:LSP-AF1-PBF-CSI-HPR-CSR-HI-CF1.677E47LSP-AF1-PBFAF1,PBF-AFWturb.drivenpumpfailure(AF1)-CC4KVpowerventilationfailure-CC250VDCpower-OE-alignCSTbackupwatersupply-Plantaircompressorsfall-CC-CompressedAirSystem(valvefailure)PBF,OEalignCSTbackupwatersupply(AF1)EVENT:InterfacingSystemsLOCA(V-Sequence)-ISL(538FA8-6.70E47-0.08%)TOPEVENT:ISL-BRH-HP2-OIB-AF4-RCE-RVC3.680E481260E48ISL-BRH-HP2-OIBISL-BRH-HP-2OI~-AF4-RCE-RVCOIBRVCOIBRVCOIBOIB,RCE,OEalignCSTbackupwatersupply(AF4)

TABLE3.4-32.3.4.5.6.7.8.9.10.11.12'13.14.15.16.17.18.19.20.21;22.23.24.25.26.27.28.29.30.31.32.33.34.35'.13E-057.78E-064.60E-062.74E-062.62E-062.12E-061.41E-061.36E.061.05E-069.84E-078.47E;078.09E.076.78E-076.78E-076.05E-075.83E-075.60E-075'3E-075'5E-074.88E-074.81E-074.66E-074.05'73.91E.073.87E-073.70E-073.59E-073.53E-072.99E-071.99E-071.83E-071.71E-071.58E-071.58E-071.58E-07575710995896955757586699758694758886IEV-COIIEV-SLOIEV-SLOIEVSLOIEV-SGRIEV-ATMIEV-SGRIEV-SLOIEV-NLOIEV-CCMIEV-SLOIEV-SGRIEV-SLOIEV-SLOIEV-SLOIEV-VDCIEVHLOIEV-SLOIEV-CCIIIEV-SLOIEV-SNSIEV-SGRIEV-SBOIEV-ATMIEV-SLOIEV-HLOIEV-SBOIEV-SGRIEV-VEFIEV-NLOIEV-SBOIEV-COIIEV-SLOIEV-SLOIEV-SGRSUC-CSISUC-HP2SUC-CSISUC-HP2SUC-AF2SUC-NRISUC-AF2SUC-CSISUC-ACCSUC-RCPSUC-HP2SUC-AF2SUC-CSISUC-CSISUC-HP2SUC-CSISUC-ACCSUC-CSISUC-RCPSUC-HP2SUC-EHBSUC-AF2SUC-AFTSUC-NRISUC-CSISUC-ACCSUC-AFTSUC-AF2SUC-CSISUC-ACCSUC-AFTSUC-RCPSUC-HP2SUC-HP2SUC-CSISUC-CSRSUC-OA6SUC-CSRSUC-CSISUC-HPISUC-AHSSUC-HPISUC-CSRSUC-HP2SUC-AF1SUC-CSISUC-HPISUC-CSRSUC-CSRSUC-OA6SUC-CSR.SUC-HP2,SUC-CSRSUC-AF1SUC-CSISUC-CSISUC-HPISUC-RCDSUC-CSISUC-CSRSUC-HP2SUC-RCDSUC-HPISUC-CSRSUC-HP2SUC-RCDSUC-AF1SUC-OA6SUC.OA6SUC-CSRSUC-HISUC-CSISUC-HlSUC-CSRSUC-SGISUCAFH.SUC-SGISUC-HlSUC-OA6SUC-CH1SUC.CSRSUC-SGISUC-HlSUC-HlSUCCSISUC-NlSUCCSISUC-HISUC-CH1SUC-CSRSUC-CSRSUC-SGISUC-AFCSUC-CSRSUC-HISUC;CSISUC-AFCSUC-SGISUC-HlSUCCSISUC-AFCSUC.CH1SUC-CSISUC-CSISUC-HIRCPSUC-CSRSUC-HIG-HHRS------CNF-HP2-------CHSUC-HlX-CH--10NE41PRX-CH--20HE41PSSUC-SSVSUC-CSISUC-CSRSUC-HISUC-CSISUC-CSRSUC-HIRPLSUC-SSVSUC-CSISUC-CSRSUC-HI0-CC-Sl-SIGNAL~SUC-CSISUC-CSRSUC-HIGHHRS----SUC-RRISUC-CSISUC-CSRSUC-HISUC-HIX-CC-COHAIRSUC-SSVSUC-CSISUC-CSRSUC-HlX-CC-COHAIRFBCV---SI101FOF-CV---SI185FOSUC-CSRSUC-HlQ.CC-HPR-RELAY2-TK-SLOMCSTHESUC-CSRSUC-HIO-CC-HP2-RELAYSUC-CSISUC-CSRSUC-HIRRI-DIAG-HH-HESUC-HlX-AN----SV44COSUC-HIRCPSUC-SSVSUC-CSISUC-CSRSUC-XH1SUC-CSISUC-CSRSUC-HIRPLAHSOXSISUC-CSRSUC-HlX-CN--10HE41PRX-CN--20NE41PSSBO-I-TR-CK-HESBO-V-TR-CK-HESUC-SSVSUC-CSISUC-CSRSUC-HIX-CH--10HE41PRUE1X-CC-COHAIR3--CHG-HHRS------CNOA6-DIAGHH-HESUC-HIX-AN----SV44COSUC-HISH1E-CC-SGPORVSUC-CSRSUC-HIP-CC-COHAIR3SBO--------XH10SUC-CSISUC-CSRSUC-Hl0-CC-SI-SIGNALSUC-CSRSUC-HIIAPN---PP35EPS-RIB--RH-VALVETHSUC-CSRSUC-HIIBPN--.PP35MPS-RIA--RH-VALVETHDHPT-----PP4PSO-CC-SI-SIGNALX-CN--20NE41PS3-182 TABLE3.4-3(Cont'd.)CDF.OUT36.37.38.39.40.41.42.43.44.45.46.47.48.49.50.51.52.53'4.55.56.57.58.59.60.61.62.63.64.65.66.67.68.69.70.1.55E-071.42E-071.42E-071.41E-071.41E-071.29E-071.24E-071.14E-071.13E-071.10E-071.07E-079.55E-OB9.49E-089.26E-089.24E-089.15E-089.15E-089.15E-089.15E-089.15E-OB9.15E-OB8.15E-OB8.14E-087.73E-087.65E-OB7.50E-OB7.41E-OB7.40E-OB7.19E-OB7.19E-087.19E-087.17E-OB717E-087.17E-OB7.17E-0876679777678598755555587998956668888IEV-HLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-LLOIEV-SLOIEV-HLOIEV-SLBIEV-LLOIEV-SLOIEV-SLBIEV-SLOIEV-SLOIEV-HLOIEV-HLOIEV-HLOIEV-HLOIEV-HLOIEV-HLOIEV-HLOIEV-HLOIEV-TRAIEV-ATWIEV-CCMIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOSUC-ACCSUC-CSISUC-CSISUC-CSISUC-KP2SUC-ACCSUC-CSISUC-ACCSUC-KP3SUC-ACCSUC-HP2SUC-CSISUC-HP2SUC-HP2SUC-ACCSUC-CSISUC-CSISUC-CSISUC-CSI.SUCCSISUCCSISUC-ACCSUC-CSISUC-HRISUC-RCPSUC-HP2SUC-HP2SUC-CSISUC-CSISUC-CSISUC-CSISUC-HP2SUC-HP2SUC-HP2SUCKP2SUC-OLISUC-CSRSUC-CSRSUC-CSRSUC-OA6SUC-LPISUC-CSRSUC-HP2SUC-CSISUCLPISUC-OA6SUC-CSRSUC.OA6SUC-OA6=SUC-CSISUC-CSRSUCCSRSUC-CSRSUC-CSRSUC-CSRSUC-CSRSUC-HP2SUC-CSRSUC-AHSSUC-AF1SUC-OA6SUC-OA6SUC-CSRSUCCSRSUC-CSRSUC-CSRSUC-OA6SUC-OA6SUC-OA6SUC-OA6SUC-CSISUC-KISUC-HlSUC-HISUC-CSISUC-CSISUC-HISUC-CSISUC-CSRSUC-CSISUC-CSISUC-HISUC-CSISUC-CSISUC-CSRSUC-HISUC-HISUC-HISUC-HISUC-HISUC-HISUC-OA6SUC-HlSUC-AFNSUC-CH1SUC-CSISUC-CSISUC;HlSUC-HlSUC-HISUC-HISUC-CSISUC-CSISUC-CSISUC-CSISUC-CSRSUC-HI0-CC-SI-SIGNALFAPH---PP26NPSFB--SI-VALVETHFBPH---PP26SPSFA--SI-VALVETHFA--Sl-VALVETHBPH---1PP7MTHESM.HULT1-7MSUC-CSRSUC-HlIA--RK-VALVETHBBPH---1PP7MTHESW-HULT1-7MSUC-CSRSUC-HlI-LPR-------CHFA--CC-TRAINTHBBPH---1PP7MTHESM-HULTT-7MSUC-CSRSUC-HlX-CC-CONAIRSUC-HIE-CC-HS1SUC-LPRSUC-HIL-CC--CTSSYS--SUC-CSRSUC-HlIBPH---PP35WPSRIA--RH-TRAINTHF-HP3-------CHSUC-CSRSUC-HlIA--RH-TRAINTHBBPH---TPP7MTHESMHULT1-7MSUC-CSRSUC-HIGAPH---PP26NPSGBPH---PP26SPSSUC-HIF-HP2------CHOLI.DIAG-SC-HENACV-SI170L3FONACV-SI166L3FONBCV-SI170L2FONBCVSI166L2FONACV.SI170L1FONACV.SI166L1FOSUC-CSISUC-CSRSUC-HlQ-CCKPR-RELAY2-TK-SLOWCSTKEX-CH-IOHE41PRX-CH--20HE41PSSUC-CSISUC-CSRSUC-HIRPLX-PC--XRV186FOSUC-RRISUC-CSISUC-CSRSUC-Hl0-CC-KPR-RELAYSUC-CSRSUC-HlIAPH---PP35EPS-RIBPH---PP35MPS-RSUC-CSRSUC-HIGAPH---PP26NPSBBPH-"1PP7MTHESM-HULTl-7MC-CC-CCM----CHFA--Sl-VALVETHCBHV--CH0420FOFA--SI-VALVETHBQ--MH0737FOFA--SI-VALVETHBBHV-1MH0702FOSUC-CSRSUC-HlIAHV--IH0340CCIB--RH-VALVETHSUC-CSRSUC-HlCAHV--CH0419CCIB--RH-VALVETHSUC-CSRSUC-HIIAHV--ICH305CCIB--RH-VALVETHSUC-CSRSUC-HlIAHV--IH0310FCIB--RH-VALVETH TABLE3.4-3(Cont'd.)~DF.OUT71.72~73.74.75.76.77.78.79.80.81.82.83.84.85.86.87.88.89.90.91.92.93.94.95.96.97.98.99.100~7.17E-0887.17E-0887.17E-0887.17E-0887.17E-0887.17E-0887.17E-0887.17E-0887.17E-0887.06E-0836.79E-0846.67E-0896.59E-0846.59E-0856.57E-0876.50E-0876.30E-0866.30E-0866.30E-0866.30E-0866.21E-08106.19E-0866.13E-08'6.07E-0866.02E-0896.00E-0875.98E-0865.86E-0865.84E-0885.80E-0810IEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-TRSIEV-SLOIEV-SLOIEV-SLBIEV-SLBIEV-HLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SLOIEV-SGRIEV-SLOIEV-SLOIEV-SLOIEV-LLOIEV-SLOIEV-LLOIEV-SLOIEV-SLOIEV-SGRSUC-HP2SUC-HP2SUC-HP2SUC-HP2SUC-HP2SUC-HP2SUC-HP2SUC-HP2SUC-HP2DNPT----SUC-CSISUC-HP2SUC-HP3SUC-CSISUC-ACCSUC-HP2SUC-CSISUC-CSISUC-CSISUC-CSISUC-AF2SUC-CSISUC-CSISUC-CSISUC-ACCSUC-CSISUC-ACCSUC-CSISUC-HP2SUC-AF2SUC-OA6SUC-OA6SUC-OA6SUC-OA6SUC-OA6SUC-OA6SUC-OA6SUC-OA6SUC-OA6-PP4PSSUC-HISUC-OA6SUC-HISUC-CSRSUC-HP2SUC-CSISUC-CSRSUC-CSRSUC-CSRSUC-CSRSUC-HPISUC-CSRSUC-CSRSUC-CSRSUC-LPISUC-CSRSUC-CSISUC-CSRSUC-OA6SUC-HPILAHV--IH0215FCIBHV--IH0350CCCBHV--CH0429CCIBHV--ICH306CCIBHV--IH0320FCLBHV--IH0225FCIA--RH-VALVETHIA--RH-VALVETHIA--RH-VALVETHSUC-HlSUC-HISUC-HISUC-HISUCHlSUC-HISUC-HlSUC-HlSUCHlIAPH---PP35EPS-RBBPH---1PP7MTHESM-HULT1-7MX-CH--1OHE41PRX-CH--20HE41THE-AH----SV32FC--2OHE41PSSUC-CSISUC-CSRIB--RH-VALVETHSUCCSISUC-CSRIA--RH-VALVETHSUC-CSISUC-CSRIA--RH-VALVETHSUC-CSISUC-CSRIA--RH-VALVETHSUC-CSISUC-CSRIA--RH-VALVETHSUC-CSISUC-CSRIA--RH-VALVETHSUC-CSISUC-CSRCBHV--CH0420FOSUC-CSISUC-CSRBBHV--MH0737FOSUC-CSISUC-CSRBBHV-1MH0702FOA-FN----FANSCH8-CC-ESMSUC-CSISUC-CSRSUC-HlQ-CC-CP-SIGNALSUC-HlQ-CC-SI-SIGNALSUC-CSISUC-CSRSUC-HlX-AH----SV44COSUC-CSRSUC-HlX-CH--10HE41PRX-CH--20HE4TTHSUC-HlFBHV--QH022600FA--CC-TRAINTHSUC-HlFA--CC-TRAINTHCBHV--CH0420FOSUC-HIFA--CC-TRAINTHBBHV--MH0737FOSUC-HlFA--CC-TRAINTHBBHV-1MH0702FOSUC-SGISUC-SSVSUC-CSISUC-CSRSUC-HlSUC-HIFAPH---PP26NPSFB--SI-TRAINTHSUC-HIFAHV--QH022500FB--CC-TRAINTHSUC-HIFAPH---PP26NPSFBPH---PP26SPSSUC-CSISUCCSRSUC-HII-1PUHPINJ--FAI-1PUHPRECIRFASUC-HIFAPH---PP26NPSBBPH---1PP7MTHESM-HULT1-7MSUC-CSRSUC-HIQ-CC-Sl-SIGNALSUC-HIFA--Sl-VALVETHBBPH---TPP7MPSSUC-CSISUC-CSRSUC-HlIA--RN-VALVETHBBPH---1PP7MPSSUC-SGISUC-CSISUC-CSRSUC-HlX-CH--10HE41PRX-CH3-184 TABLE3.44COMPLHKVersion2.2011/2/199120:36:31~DPIMPFilecreatedbylinkingCOF.NLKWLINKVer.2.31SYSTEMUHAVAILABILITY(O)6.26E-05NUMBEROFBASICEVENTS>520NUMBEROFCUTSETS=3228BASICEVENT,IMPORTANCE¹CSCONT.TOOFAILUREPROBABILITY123456789101112131415161718192021222324252627282930313233343536373839404142SUC-HISUC-CSISUC~CSRIEVSLOSUC-HP2SUCOA6IEVCSRCPG-HKRS----CHIEV-SGRSUC-AF2SUC-KPISUC-SGIX-CH--20HE41PSX-CM--1OHE41PRSUC-SSVF-HP2"--CHSUCACCIEVHLOIEV-ATMRPLSUC-MRISUC.AF1SUCRCPSUC-CK1SUCAHSSUC-AFHUE10-CC-Sl-SIGNALX-CCCONAIRX-CC-CONAIR3SUC-RRIIA--RH-VALVETHBBPH"-1PP7iJTHESM.HULT1-7WIEV-SBOX-AH--.-SV44COSUC-RCO2-TK-SLNCSTKESUC-AFTSUC-AFCIEVLLO98.1397;9596.4847.2933.9024.4322.0918.8315.8211.2810.8810.8210.6310.4010.249.577.537.236.894.554.524.444.284.233.983.903.S33.393.283.032.842.722.222.032.031.811.741.711.641.641.631.513114306526581290127911101629523032812742311859713346802587115999725624215396661043252721214016416426201811117142276.148E-056.137E-056.044E052.963E-052.124E-051.531E-051.384E-051.179E-059.913E.067.067E.066.814E-066.777E-066.660E.066.517E-066.416E-065.995E.064.717E064.532E.064.3'17E-062.853E.062.834E-062.781E-062.683E-062.651E.062.491E-062.443E-062.401E.062.123E062.056E-061.896E-061.779E-061.706E-061.389E-061.271E-061.271E-061.132E-061.092E.061.073E.061.030E.061.028E.061.022E-069.437E.079.998E-019.994E-019.987E-016.800E-039.983E-019.983E-018.710E-041.300E-021.150E-037.200E-039.999E.019.997E-019.975E-018.440E-024.800E-039.032E.016.780E.049.994E.019.170E-044.670E-058.400E-019.986E.019.999E-019.870E-019.987E-019.900E-019.989E-015.480E.022.000E-041.250E-042.180E-049.990E-017.020E.031.480E.032.GOBE+001.400E-057.200E-059.984E-015.300E-059.411E-019.943E-013.000E-043-185 TABLE3.4A(con't)~DF.IMP434445464748495051IA--RH-TRAINTHIAPH"-PP35EPS-RFA--Sl-VALVETHQCC-HPR-RELAYIB--RM-VALVETHF.CV.--S1185FOFBCV"-SI101FOFA--CC-TRAINTHIBPH--PP35WPSR52BBHV.1WM0702FO53'BMV--00737FO545556575859606162636465676869707172.73CBMV--CHO420FOIEV-SMSIEV-VDCSUC-LPIOA6DIAG-HN-NEQXSIIEVSLBQ-CC-NP2-RELAYDNPT-----PP4PSRRIDIAGHNMEFAPN.--PP26NPSBBPH-.-1PP7MPSSUC-EHSGAPH---PP26NPSE.CC~SGPORVIAHV-IH0310FCLANV"IN0215FCSUC-XM1IANV"ICH305CCSBO-V-TR-CK-HE7879'08182838485868788899091'92939495SBO-ITRCK-MEIBHV--IHO320FCLBMV--IH0225FCIBNV"ICH306CCCBHV"CH0429CCIBNV--IHO350CCSUC-LPRFBPH---PP26SPSFA-Sl-TRAINTHIEV-VEFIEV-TRAIEVTRSSUC-HP3FB--SI-VALVETHQBREK610X'IKFAMV--QM02250018--RK-TRAINTHQBREK604K74CANV"CHO419CC75IAMV--IM0340CC76SN1ANS1.491.471.251.231.181.171.111.091.091.031.001.00.96.96.94.92.92.91.90.89.89.86.83.79.78.71.69.69.69.68.68.66.66.65.63'62.52.52~51.49.49.48.48.48.48.46.45.41.38.37.37~37.37114'11865147314119558119929289261961118'152'111374491055771311211251038838313666666'1474798,19442341042723600I5649599.357E-079.185E.077.848E-077.695E-077.383E.077.312E-076.939E-076.848E-076.837E-076.429E-076.256E-076.256E-076.041E-076.037E-075.899E-075.794E-075.752E-075.688E-075.660E-075.589E-075.548E-075.393E-075.227E-074.97SE-074.898E-074.445E-074.329E-074.329E-074.293E-074.284E-074.267E.074.117E-074.117E-074.050E-073.917E-073.886E.073.247E-073.247E-073.221E-073.083E-073.083E.073.031E-073.013E-073.003E-072.991E-072.852E-072.825E-072.542E-072.398E-072.338E-072.299E-072.291E-072.287E.074.740E-033.330E.037.020E-038.940E-057.020E031.000E041.000E-046.150E-033.330E031.510E-031.510E-031.510E.033.730E.051.160E.029.994E-016.130E-045.70OE-053.300E.048'50E-051.100E.016.130E-042.990E-031.230E.039.935E-013.700E.035.450E.051.510E-031.510E.039.557E.011.510E035.100E-011.510E.031.510E-033.300E.021.000E.025.460E-021.510E-031'10E.031.510E-031.510E-031.510E.039.987E-012.990E-032.710E-033.000E-073.BODE+001.200E.019.990E.017.020E.035.700E-041.510E.032.190E-035.700E-043-186 3.4.2VulnerabBityScreening@TheinformationsummarizedinTables34-1and3.4-2formthebasesforsequencescreeningandidentificationofvulnerabilities.Table3.4-2showsthesequencesforeachaccidentstartingwiththemostdominantaccident(smallLOCA)andproceedingindescendingorderofcontributiontocoredamagefrequency(CDF).AsseeninTable34-1,smallLOCA(SLO),LossofComponentCoolingWater(CCW)andSteamGeneratorTubeRupture(SGR)arethetopthreecontributingaccidentstoCDFwithcontributionsof47.3%(SLO),22.1%(CCW)and11.3%(SGR).FortheSLOevent,failureoftheEmergencyCoreCoolingSystem(ECCS)duringeitherthecoldleginjectionorrecirculationphasesproducedthetwoleadingsequenceswithintheSLOevent(Table3.4-2.)Commonmodefailureofthesafetyinjection(Si)pumps(partofECCS)andfailureoftheEngineeredSafetyFeatures(ESRsystemtoactuatetheECCSdominatedthesetwosequences.Thethirdleadingsequenceresultedfromfunctionalfailurestocooldownthereactorcoolantsystemfollowedbyfailuretoinitiateprimaryfeedandbleedcooling.Hardwareandcommonmodefailuresinthecompressedairsystem,whichsuppliesairtothepressurizerandsteamgeneratorPORVs,contributedmostlytothesefailures.Alsonotethatallthreesequencesarewithintheupper95%ofCDF.TheLossofCCWevent,likeSLO,wasdominatedbythreesequences(seeTable3.4-2).Operatorfailuretotripthereactorcoolantpumps(RCPs)afterlosingsealcoolingfromCCW,whichleadstogrosssealfailure,solelycontrolledthissequence.Withinthesecondsequence,coldlegrecirculationdominatedbyacommonmodefailureoftheSIpumpsagainturnedup,asinSLO.Thethirdsequencewascontrolledbythefunctionalfailuretorestorereactorinventory(RRI)afterCCWwasrestored(whichthenallowsuseoftheECCSchargingpumps).Here,operatorerrorandESFsignalfailuresdominated.Onlythefirstsequence(tripRCPs)iswithintheupper95%ofCDF.TheSGReventhadmultiplesequencescontributingtoit.Ratherthandiscusseachsequence(whichisshowninTable3.4-2),itisnotedthatcompressedairsystemfailures(hardwareandcommonmode)andESFsignaltroubleagainappearedasdominant.Additionally,thetopsequencewasinfluencedbysteamgeneratorPORVcommonmodefailures.'heSGRevent,inadditiontotheinterfacingsystemsLOCA(ISL)event,isalsosignificantsincethecontainmentisbypassed.TheISLeventisalsoshowninTable3.4-2.PerNUREG-1335,sequencesfromtheseaccidentsgreaterthanLOE-08werereviewed.TheISLeventwastheleastcontributortoCDF.Evenso,theseeventsareimportantsincefissionproductsourcetermsaredirectlyreleasedtotheenvironment.Table3.44listsanoverallimportancerankingfortheCDFquantification.Asexpected,thoseindividualitemsthatcontributedtotheSLO,CCWandSGReventsaremostimportant.Thefailuretotripthereactorcoolantpumpsafterlosingsealcoolingandtheplantaircompressorfailuresaresignificant,nexttotheECCSrelatedcommonmodefailures.Thereactorcoolantpumpsareimportantsincegrosssealfailurewasassumeduponalossofsealcooling.TheplantaircompressorsareimportantbecausethepressurizerandsteamgeneratorPORVsneedcontrolairtooperatetoallowsecondarysidecoolingandprimaryfeedandbleed.TheUnit1controlaircompressorandbackupPORVairsupplieswerenotmodeledduetoeithercapacityoravailabilityconcerns.FollowingfurthersensitivityanalysisonthecontrolairsystemandtheSLOeventtree,itwasfoundthathadamorerefinedmodelbeenusedwithintheSLOeventtree,itwouldhavenoticeablyloweredtheSLOcontributiontoCDFandreducedthesignificanceofthecontrolairsystemfailures.3.49DecayHeatRemovalEvaluaGoa(USIA-45)ThissectionprovidesabriefevaluationofthedecayheatremovalfunctionsattheCookNuclearPlant.Thepurposeofthissectionistoexaminewhetherornottherisksassociatedwithalossofdecayheat3-187 removalcanbeloweredinacosteffectivemanner.AsstatedinNUREG-1289(Reference64),thisissueisconcernedwithsmallbreak(lessthan6"equivalentdiameter)LOCA,transient,andlossofoffsitepowerevents.Decayheatremovalduringthefirst24hoursfollowingaplanttripisaccomplishedbythefollowingkeyfunctionsatCookNuclearPlant:oDuringamedium(2"to6"diameter)LOCAevent,decayheatisremoveddirectlybytheEmergencyCoreCoolingSystems(ECCS).Thisincludesthecharging,safetyinjection(Si),andresidualheatremoval(RHR)injectionandrecirculationsystems,andassociatedoperatoractions.oDuringasmall(3/8"to2")breakLOCA(SBLOCA)event,therewillnotbeenoughflowfromthebreaktodirectlyremoveadequatedecayheat.ForSBLOCAs,decayheatisremovedthroughthesecondarysideofthesteamgeneratorsbytheauxiliaryfeedwater(AFW)ormainfeedwater(MFW)systemwhilereactorcoolantsystem(RCS)inventoryismaintainedbyECCSirjectionandrecirculation.Ifthedecayheatremovalthroughthesecondarysidesystemsfails,bleedandfeedoperationsareneededontheprimaryside,Thebleedandfeedoperationrequiresahighpressureinjectionsystem,thepressurizerPORVs,andassociatedoperatoractions,Duringatransientevent(includingalossofoffsitepowerevent),decayheatisremovedthroughthesecondarysideofthesteamgeneratorsbytheAFWandMFWsystems.UnliketheSBLOCAevent,however,RCSinventorymakeupisnotrequired.Shouldthesecondarysystemsfail,thenprimarybleedandfeedoperationswouldbeinitiated,EvaluationofUSIA45wasaddressedforbothinternalandexternalinitiatingevents.TheseevaluationswerebasedontheresultsoftheCookNuclearPlantIPEandIPEEEandaresummarizedbelow.3.4.3.1InternalEventsEventtreesweredevelopedbytheCookNuclearPlantIPEtomodelthemostimportanteventsandsystemsnecessarytomitigatetheabovelistedaccidents.AsstatedinSection3.1.2ofthissubmittal,thesuccesscriteriaforthetopeventsmodelledwithintheeventtreesalsoconsideredtheeffectofthetopeventonbothcoreheatremovalandcontainmentresponse.Insomecases,thesuccesscriteriaspecifiedintheeventtreesweremorerestrictivethanrequiredtosolelyremovedecayheatbecauseoftheconsiderationofthecontainmentresponse.Giventhatsuccessfuldecayheatremovaldependsontheabovesystemsandoperations,thefollowingdiscussionofthesefunctionsandtheirrespectivefeaturesisprovided.oTheAFWsystemconsistsofthreeredundanttrains:twotrainscontainamotordrivenpumpandthethirdcontainsaturbinedrivenpump.Eachofthemotor-drivenAFWpumpsfeedtwosteamgeneratorseach.Theturbine-drivenAFWpumpiscapableoffeedingallfoursteamgenerators.ThenormalwatersupplytotheAFWisfromthecondensatestoragetank(CST)andcanbesupplementedwithessentialservicewaterorwiththeoppositeunit'sCST.ThesebackupsuppliesaremodeledintheCookNuclearPlantIPEAFWsystemfaulttreessincetheCSTmaynotcontainenoughwatertoremovedecayheatforafull24hours.ThefailureprobabilityoftheAFWsystemwascalculatedtobe6.69E45withallsupportsystemsavailable.Therefore,thefailureoftheAFWsystemwasfoundtobeaninsignificantcontributortothecoredamagefrequency.oIftheaffectedunit'sAFWsystemisnotavailable,theoperatorsaredirectedtoattempttocrosstietotheoppositeunit'smotor-drivenAFWpumps.Itispossibleforeachoftheoppositeunit'smotordrivenAFWpumpstosupplytwooftheaffectedunit'ssteamgenerators.ThefailureprobabilityoftheAFWcrosstiewascalculatedtobe2.43E-04.Consideringthatthecrosstieisonlyusedifthe3-188 affectedunit'sAFWsystemfails,thisfailureprobabilityisconsideredsufficientlysmalltohaveaninsignificantimpactonthecoredamagefrequency.loIfitisnotpossibletocrosstietheAFWsystems,theoperatorthenattemptstoestablishanalternatefeedwaterflowtothesteamgeneratorsviathemainfeedwaterpumps.TheMFWsystemincludesthefollowingcomponents:twoturbine-drivenmainfeedwaterpumps,twomainfeedwaterheaterstrings,andtwomainfeedwaterpumpcondensers.Inaddition,theMFWsystemrequirescoolingfromthecondensatesystemandthecirculatingwatersystem.TheMFWsystemisrequiredtooperatewhenbothunits'FWsystemsfail.Asdescribedabove,thisisveryimprobable.ThefailureprobabilityoftheMF1event,whichincludesthefailureoftheMFWandcondensatesystems,wascalculatedtobearelativelylowvalueof1.66E-04.oWithnofeedwaterflowtothesteamgenerators,theoperatorsareinstructedperEOPOHPM23.FR-H.1(Reference4)toinitiateprimarysidebleedandfeedcooling.ThecoolingpathisfeedingfromthehighheadECCS(chargingandSi)systemandbleedingfromthepressurizerPORVs.TwoofthethreepressurizerPORVsarerequiredforthebleedoperationinordertopreventoverpressurizationoftheRCSduringvariousaccidentconditions.ThehighheadECCSwasmodelledinthelevelIquantificationasrequiringoneoftwoSIpumpsandoneoftwochargingpumpstoprovideflowtotheRCS.Therequirementfortwopumpswasduetoconsiderationofthecontainmentresponse.Fordecayheatremovalpurposes,however,onlyoneoffourECCSpumpswouldbesufficient(Reference4).ThebleedandfeedoperationisusedonlywhenboththeAFWandMFWfails,whichisveryimprobable.Theoperatordiagnosisandactionwascalculatedtohaveafailureprobabilityof1.86E-04,ThefailureprobabilityoftheentirebleedandfeedoperationasmodelledintheIPEis2,19E-03,oThehighheadinjectionsystemoftheECCSconsistsof2SIand2chargingpumps.Thefailureprobabilityofthissystem(HP2)wascalculatedas1.2E-03.oThelowpressureinjectionsystemoftheECCSconsistsof2RHRpumpswhichcanbeusedwhentheRCSpressureisbelowtheshutoffheadoftheRHRpumps.Thefailureprobabilityofthissystem(LPI)wascalculatedtobearelativelylowvalueof3.1E44.oWhenthelowlevelRWSTalarmsetpointisreached,theoperatorstransferfromtheinjectiontotherecirculationphasebaseduponEOPOHPM23.ES-1.3(Reference4).TheoperatorfailuretoperformatransfertoECCSrecirculationisincludedinthehighheadandlowheadrecirculationmodels.ThefailureprobabilityofthisoperatoractionforhighheadECCSrecirculationis6.31E-06andthefailureprobabilityforthelowheadrecirculationis5.31E-05.oThehighheadrecirculationsystem(HPR)consistsofthe2SIand2chargingpumpswhichcanbeusedtomaintaintheplantinalong-termstableconditionforsequenceswiththeRCSpressureabovetheRHRpumpshutoffhead.ThismodeofoperationrequiressuctionfromtheRHRpumps.Thefailureprobabilityofthissystemwascalculatedas1.3E43.oThelowheadrecirculationsystem(LPR)consistsof2RHRpumpswhichcanbeusedtomaintaintheplantinlong-termstableconditionforsequenceswiththeRCSpressurelessthantheRHRpumpshutoffhead.Thefailureprobabilityofthissystemwascalculatedtobearelativelylowvalueof8,5E-04.)ThedominantaccidentsequencesforplantcoredamagearediscussedindetailinSection3.4.TheseaccidentsequencesweretheproductofthelevelIquantification,whichlinkedsupportsystemsintothe3-189 eventtreetopeventnodes.Thus,failurevaluesassociatedwiththesesequencesaccountforsupportsystem(componentcoolingwater,essentialservicewaterandsafetyrelatedelectricalsystems)contributionstofailure.OftheitemsinSection3,4,thosewhichareapplicabletofailureofthedecayheatremovalfunctionandnotconsideredjustfortheeffectoncontainmentresponseandwhosefrequencyisgreaterthan1EA/yrarepresentedbelow.NotethatthelistedcoredamagefrequencycorrespondswiththeinformationpresentedinSection3.4.CoreDamage~FreuenInitiating~EventernFailures1.35E45SLOHPRfailsduetocommoncausefailuresoftheHPsystemduringrecirculationphase1,17E-05SLOHP2failsduetocommoncausefailuresoftheHPsystemduringinjectionphase1.63E-06CCWHPRfailsduetocommoncausefailures1.80E-06MLOHPRfailsduetocommoncausefailuresAspresentedabove,theECCSsystemisthedominantcontributortothefailureofthedecayheatremovalfunctionattheCookNuclearPlant.ThetablebelowpresentstheresultsofanimportanceanalysisofthedominantcontributorstotheCookNuclearPlantcoredamagefrequencywhicharerelevanttothefailureofthedecayheat'removalfunction.ImportanceQoOntributinEventDcritin16%HPR-CommonCauseFailures8%3%HP2-CommonCauseFailuresESFASSignals-CommonCauseFailuresAsdiscussedinSection3.3.4,thecommoncausefailureprobabilitiesfortheECCSsystemareconsideredtobeconservativeduetotheapplicationofgenericmultiplegreekletter(MGL)factorsandthemethodinwhichallcommoncausefailuresarelumpedintoonefailureevent.ItisexpectedthattheHP2andHPRcontributionstocoredamagewoulddecreaseifCookNuclearPlantspecificMGLfactorswereanalyzedandseparatedoutbysimilarcomponentsinsteadofgroupingthefailureprobabilitiesofallcomponentswithinthesystemintoonecommoncausefailureevent.Tosummarizetheinformationpresentedinthissection,thereareseveralredundantmeansfordecayheatremovalattheCookNuclearPlant.Allofthedecayheatremovalfunctionshaverelativelylowfailureprobabilitiesandthosewhichdocontributesignificantlytotheplantcoredamagefrequencyareeitherconservativelycalculated(highpressurecommoncause)or,aswiththecaseofthecontrolairsystem,arebeingreviewed.3.4.3.2InternalFloodingInternalfloodingvulnerabilitiesatCookNuclearPlantwereanalyzedusinganinternalfloodingPRA.Consistentwiththeinternalinitiatingeventspreviouslydiscussed,plantsystemsandtheexpectedplantresponsestovariousfloodingeventswereanalyzedusingquantitativetechniques.AEPSCcalculationsand3-190 detailedplantwalkdownswereusedtodeterminethoseareasintheplantthatwerevulnerabletointernal,flooding.Allareasinsidetheplantwereanalyzedtodeterminethelikelihoodofaccidentinitiation.Thejonlyeventofsignificantprobabilityfoundtorequirefurtheranalysiswasatransientwithoutsteamconversionsystemsavailablecausedbyafioodintheturbinebuildingsub-basement.Consistentwiththeinternaleventsquantification,theinitiatingeventwascalculatedandthesupportsystemswerelinkedintotheaccidentevents.Theeventtreeusedtoquantifytheeffectsofinternalfloodingwasbasedontheinternaleventsevent/faulttrees.Therefore,onlytheinternalfioodingdominantcontributorsimpactingdecayheatremovalarediscussedhere.TheinternalfloodingcoredamagefrequencyforCookNuclearPlantis2.00E47/year.ThedominantcontributorsarefailureoftheNESWpumpsduetotheflood,andthesubsequentfailureofthecompressedairsystemduetolossofNESWcoolingtothecompressors.Failureofthecompressedairsystemwillresultinfailureoftheabilitytoprovideprimarybleedandfeedcooling,oneofthemethodsofdecayheatremoval,Asdiscussedinsection3.4.3.1,theAFWsystemandthecrosstieofAFWflowtotheoppositeunit'sAFWsystemaretheprimarymeansofdecayheatremovalfortransients.TheinternalfloodingPRAdeterminedthatthesearenotaffectedbyfioodingatCookNuclearPlant.Additionally,availabilityoftheECCSisnotaffectedbyinternalfiooding.Itis,therefore,concludedthatfloodingeffectsondecayheatremovalsystemsatCookNuclearPlantarenotasignificantconcern.3.42.3ExternalEventsSeismicContributors:TheseismicportionofthisprojectwasaddressedbymodellingplantsystemsandseismicallyinitiatedaccidenteventsinaseismicPRA(SPRA)thatevaluatedseismiclevelsbeyondthe0.2gdesignbasisearthquake(DBE)forCookNuclearPlant.ThisprocesswasverysimilartotheinternaleventssequencequantificationdescribedinSection3.3.5.Transients(feedwaterfailure),LOCAs(small,mediumandlarge)andLossofOffsitePowereventswereamongtheaccidenteventsanalyzedintheSPRA.Plantwalkdowns,whichreviewedspatialinteractionsandequipmentmountings,andacomponentfailure(fragility)analysisprovidedinputtotheSPRA.3Aswiththeinternaleventsquantification,supportsystemcontributionswerelinkedintotheaccidentevents.TheSPRAeventtreesandplantsystemfaulttreeswerebasedontheinternaleventsevent/faulttrees(modifledforseismicevents).Therefore,onlytheseismicdominantcontributorsimpactingdecayheatremovalarediscussedhere.Theseismiccore.damagefrequencybasedonasitespecificseismichazardcurveis1.83E-05.ThedominantseismiccontributorsaffectingdecayheatremovalareAuxiliaryBuildingfailure,4kV/600VACtransformerfailureandemergencydieselgenerator(EDG)fueloildaytankfailures.Thesedominantcontributorsarecurrentlydesignedtowithstanda0.2gDBEatCookNuclearPlantandfailedatlevelshigherthan0.2gintheSPRA.AuxiliaryBuildingfailurewasconservativelyassumedtodestroyallcomponentsinside,whichincludedtheECCSpumps,componentcoolingwatersystemandmuchofthesafetyrelatedelectricalpowersystem.Additionally,fueloildaytankandelectricaltransformerfailuresweregovernedbyfailuresofadjacentwalls,wallswhichmeetDBEcriteria.Theveryconservativeassumptionofauxiliarybuildingfailurecoupledwithelectricalfailuresbecamedominantbeyondthe0.2gDBE.Thus,itisconcludedthatseismiceffectsondecayheatremovalsystemsatCookNuclearPlantarenotasignificantconcern.InternalFireContributors:InternalfirevulnerabilitiesatCookNuclearPlantwereanalyzedusinganinternalfirePRA.Asfortheinternalinitiatingeventspreviouslydiscussed,plantsystemsandtheexpectedplantresponsestovariousfireswereanalyzedusingquantitativetechniques.InternalAEPSCdocumentationsupportingthework'i3-191 performedinresponseto10CFR50AppendixRanddetailedplantwalkdownswereusedtodeterminethoseareasintheplantthatwerevulnerabletointernalfires.Allareasinsidetheplantwereanalyzedtodeterminethelikelihoodofaccidentinitiation.TheonlyeventofsignificantprobabilityfoundtorequirefurtheranalysiswasaLossofaSingleTrainof250VDCPower.TheonlyzonesrequiringextensivequantiTicationwerethezoneshousingtheEngineeredSafetyFeaturesswitchgearandthecablevaults.Aswiththeinternaleventsquantification,theinitiatingeventwascalculatedandthesupportsystemswerelinkedintotheaccidentevents.Theeventtreeusedtoquantifytheeffectsofinternalfirewasbasedontheinternaleventsevent/faulttrees.Therefore,onlytheinternalfiredominantcontributorsimpactingdecayheatremovalarediscussedhere.TheinternalfirecoredamagefrequencyforCookNuclearPlantis1.65K@7/year.Thedominantcontributorsarefailuresofelectricpowerbusesthataredestroyedbythefire.Thecontributiontocoredamagefrequencyislowand,therefore,itisconcludedthatfireeffectsondecayheatremovalsystemsatCookNuclearPlantarenotasignificantconcern,OtherExternalEventsContributors:Thissectiondiscussesthosevulnerabilitiesattributabletoanyexternaleventotherthanseismicevents,internalfloods,andinternalfires.Specificallyexaminedintheotherexternaleventsanalysisareexternalflooding,aircraftaccidents,severewinds,shipimpactaccidents,off-siteandon-sitehazardousmaterialsaccidents,turbinemissiles,andexternalfires.AnapproachwhichmeetstheintentofthatdisplayedinFigure1ofGenericLetter88-20,Supplement4(Reference9)wasusedintheevaluationofotherexternalevents.Existinginformationandanalyseswereutilizedasmuchaspossibletoanalyzethesubjectevents.Novulnerabilitieswereidentifiedthatrequireddetailedquantificationofanyaccidentevents.Itis,therefore,concludedthattheeffectsondecayheatremovalsystemsfromanyoftheotherexternaleventsdescribedherearenotasignificantconcernatCookNuclearPlant.3.4.4USIandGSIScreeningTheIPEandIPEEE(ExternalEvents)addressedthefollowingissues:1.USIA45,ShutdownDecayHeatRemovalRequirements.2.USIA-17,SystemInteractionsinNuclearPowerPlants.3.NUREG/CR-5088,"FireRiskScopingStudy".4.GI131,PotentialSeismicInteractionInvolvingtheMovableIn-CoreFluxMappingSystemUsedinWestinghousePlants.5,TheEasternU.S.Seismicity(TheCharlestonEarthquake)Issue.USIA45isaddressedinSection3.4.3.USIA-17wasaddressedthroughbothIPEandIPEEEplantwalkdowns.TheremainingissuesareaddressedintheIPEEEsubmittalforCookNuclearPlant.3-192 4.0BACKENDANALYSISThefollowingsectionsdescribethebackendanalysisoftheCookNuclearPlantIPE,ThearrangementofthisportionofthesubmittaldiffersslightlyfromtheorderspeciTiedinReference20.BecauseofthewayinwhichtheCookNuclearPlantLevel2analysiswasconducted,thisrearrangementofsectionswasmadetomakethesubmittalfollowadear,logicalpattern.4.1ContaimnentAnalysis4.1.1ContainmentDescriptionTheCookNuclearPlantcontainmentisdescribedbelow,alongwiththosecontainmentsystemswhichareimportanttothecontainmentandsourcetermanalysis.Detailedplant-specificdataareusedtomodelthesecontainmentfeaturessoastorealisticallyevaluatethecontainmentresponsetoacoremeltaccident.4.1.1.1ConfaimnentStructureTheCookNuclearPlantcontainmentisaWestinghouseicecondenserdesign.Theplantcontainmentissectionedintoseveralcompartmentsconsistingofatotalfreevolumeofapproximately1,300,000cubicfeet.Figure4.1-1illustratesaverticalsectionoftheCookNuclearPlantcontainment.Thelargecontainmentvolumeabovetheoperatingdeckisreferredtoasthe"UpperCompartment."The"LowerCompartment"isthatportionofcontainmentwhichisinsidethecranewallbutoutsidethebiologicalshieldwallandisbetweenthecontainmentfloorandtheoperatingdeck.The"AnnularCompartment"isthatpartofcontainmentbelowtheoperatingdeckbutoutsidethecranewall.The"Cavity"includesthereactorcavityandtheinstrumenttunnel.Separatecompartmentsaremodeledforthe"IceCondenser"and"IceCondenserUpperPlenum."Figure4.1-2isaschematicoftheCookNuclearPlantcontainmentcompartments,showingtheirfreevolumesasmodelledinthelevel2analysisandthecrosssectionalareaassociatedwiththeflowpathsbetweenthesesections.Thefloorofthelowercompartmentisatelevation598'-9".Waterbeginstospillfromthelowercompartmentintothereactorcavityatelevation610'-0".AsshowninFigure44-1,thelowerandannularcompartmentsareseparatedbythecranewallwithlargeventilationopeningsallowingcommunicationbetweenthetwocompartments.Thetopoftheseventilationopeningsisatelevation612'-0".Inaddition,therearesmalleropeningsthroughpipingsleeveswhichallowsystempipingtopassfromtheannularcompartmenttothelowercontainment.Whilethefiowareaofeachofthesesleevesissmall,therearenumeroussleevesanditisbelievedthettheseopeningswillallowwaterlevelinthelowerandannularcompartmentstoequalize.FlooduplevelintheCookNuclearPlantcontainmentistoapproximately614'ftheentirecontentsoftheRWST,accumulators,reactorcoolantsystem(RCS),andicecondenserareconsidered.Becauseofthepipingsleevesmentionedabove,inijectionoftheRWSTalonewillprobablynotallowwatertospillfromthelowercompartmentintothecavityuntilsufficienticehasmeltedtoraisethewaterlevelinboththelowerandannularcompartmentstothe610'-0"elevation.Theicecondensercontainmentisdesignedasavaporsuppressionsystem.Iceisaone-time,non-renewablevaporsuppressant.Icemassmaintainedduringnormaloperationistypicallygreaterthan2.37xl0sIbm.Thephysicaldesignoftheicecondensercontainmentisthatallhighenergypipingiscontainedintheportionofcontainmentbelowtheoperatingdeck.Thisensuresthatallenergyreleasedfromanypipebreaksisreleasedtothelowercompartment.Energyreleasedfromaccidentsinthelowercompartmentforcesamixtureofair,waterandsteamintotheicecondenser.Herethesteamiscondensedthroughcontactwiththeicesurface,limitingcontainmentpeakpressures.Aircontinuestofiowthroughtheicecondenserandintotheuppercompartment.Recirculationfansreturnthecooledairtotheannularcompartmentwhereitflowsbacktothelowercompartment.

Thereactorcontainmentstructureisareinforcedverticalconcretecylinderwithaslabbaseandahemisphericaldome.Aweldedsteellinerisprovidedasamembranetopreventleakage.Theicecondenserrunscircumferentially(300')betweenthecranewallandtheoutercontainmentwall,extendingaboveandbelowtheoperatingdeck.Doorpanelsarelocatedattheupperportionoftheicecondenserabovetheoperatingdeckandatthebottomoftheicecondenser.Thesedoorsopenwhenanaccidentcreatessufficientdifferentialpressurebetweentheloweranduppercompartments.AdetaileddescriptionoftheCookNuclearPlantcontainmentcanbefoundinchapter5oftheUFSAR.PgTheCookNuclearPlantcontainmentstructureactsasafissionproductbarrier.Howeverreleasesfromthecontainmentmayoccurduringseverecoremeltaccidentsduetoeitherpreexistingleakagepathwaysorbreachescausedbystructuralfailures.Containmentstructuralfailuresmayresultduetocontainmentoverpressurizationfollowingdepletionoftheicecondenserinventory.ContainmentfailuremodesaresummarizedinSection4.3ofthissubmittalandarebasedonphenomenologicalevaluationsummariescompletedaspartoftheSourceTermNotebook.Thelatterarediscussedinthefollowingsection.AsdiscussedinSection4.3,containmentfailureintheannularcompartmentatthebasematlcylinderjunctionisassumedforuseinthesourcetermanalysisandsomeofthewateronthefloorofthecontainmentisassumedtoleavecontainmentthroughthisbreak.Thecontainmentwouldcontinuetopressurizewhilewaterisdischargedthroughthebreak,butwouldsubsequentlydepressurizeoncethewateronthefloorwasdepleted.4.1.1.2ContainmentSystemsTheCookNuclearPlantcontainmentdesignreliesoncontainmentsprayrecirculationforlongtermcontainmentheatremoval.Containmentsprayinjectionisonlyashorttermcontainmentpressurereductionsystem.ThecontainmentspraysystemcanbesupplementedbytheRHRspraysbydivertingtherecirculationflowoftheRHRsystemfromthecoretotheRHRsprayheaders.Thehydrogenignitersystemandthecontainmentrecirculationfanshelppreventtheaccumulationandstratificationofhydrogenincontainment.Significantdesignaspectsofthesesystemsarediscussedbrieflybelow.~)ContainmentSraIn'ectinandRecirculationThecontainmentspraysystemprovidesspraycoolingwatertothecontainmentatmosphereviasprayringheaderslocatedonthecontainmentdomeandinthelowerandannularcompartments.Thesystemconsistsoftwoindependent100%capacityflowtrains,eachofwhichisdesignedtoprovide3200gpmtotheringheaders.ThecontainmentspraysystemisillustratedschematicallyinFigure4.1-3.Asinglerefuelingwaterstoragetank(RWST)andsprayadditivetankservethetwotrains.Additionalindependentringheadersintheuppercompartmentaresuppliedbytheresidualheatremoval(RHR)systemandcanbeusedtosupplementthecontainmentspraysystem.Inordertoallowspraywaterintheuppercompartmenttoreturntothelowercompartment,therearethreedrainholesintherefuelingcanalwithacombinedflowareaofabout2.2fthm.Thisdirectflowfromthelowertotheuppercompartmentsistheonlydirectcommunicationbetweenthesecompartments.Operationofthecontainmentspraysystemisautomaticallyinitiatedwhencontainmentpressureincreasesabove29psig.BothcontainmentspraypumpsarestartedandwaterispumpedfromtheRWSTtothespraynozzles.WhentheRWST-lowlevelalarmisreceived,transfertorecirculationwillbeinitiatedbythecontrolroomoperators.TheoperatorsmuststoptheoperatingcontainmentsprayandRHRpumps,dosethevalvesinthesuctionlinetotheRWST,verifycoolingwater'tothecontainmentsprayheatexchangers,opentheisolationvalvesfromtherecirculationsump,thenrestartthepreviouslyoperatingpumps.Intherecirculationphase,waterthatisinjectedbycontainmentsprayandspilledfromthebreakcollectsinthelowercontainmentandflowstocoarseandfinemeshstrainersintotherecirculationsump.Thisallowsthewatertobecooledduringsprayrecirculation.Eachcontainmentspraysystemheatexchangerisdesignedtoremove107.8MBtu/hr.

TheRHRsystemcanbeusedduringtherecirculationphasetosupplementthecontainmentspraysystem.Thisoperationwouldbeinitiatedbytheoperatorsintheeventcontainmentpressureincreasesto8psigaftertheinitialblowdown.Anoff-takefromeachofthetwoRHRtrains,downstreamoftheRHRheatexchangers,supplies2,000gpmtotwoRHRsprayringheadersintheuppercompartment.FlowfromatrainoftheRHRsystemtothecoremustbeterminatedbeforetheRHRsprayisinitiated.AllowinganRHRpumptosimultaneouslysupplythecore,centrifugalchargingandsafetyirjectionpumpsuctions,andtheRHRsprayheadersisprohibitedasthiscouldresultinRHRpumprunout.DistributedInitionternIThecontainmentisprovidedwithadistributedignitionsystem(i.e.,hydrogenigniters)forpostaccidenthydrogencontrolinordertominimizehydrogenbuildupinthecontainmentatmosphere.Therearetwotrainsofignitersemployingatotalofseventyigniterassemblies(glowplugs)locatedthroughoutthecontainmentbuilding.Onceenergizedbythecontrolroomoperators,theigniterscauseanycombustiblemixturesneartheignitertoignite,therebyhelpingtosupportcontinuousburnsandeliminateanylargehydrogenaccumulations.AirRirulatin/HdronkimmerternTheAirRecirculation/HydrogenSkimmerSystemistheonlysafetyrelatedventilationsysteminthecontainment.Thissystemisactivatedbyacontainmentpressurehigh-highsignal(i.e.,whencontainmentpressurereaches2.9psig).Thesystemconsistsoftwoindependentsystemswhichincludefans,backdraftdampers,valves,pipingandductwork.Theprimaryfunctionofthissystemistopreventhydrogenpocketingandstratification.Inaddition,thesystemaidsinmaintainingcontainmentpressurewithinthelimitsofaccidentanalyses.Thesystemoperatesbycontinuouslyblowingairfromtheuppercontainmentthroughtheannularcompartmentintothelowercontainment.Hydrogenpocketingispreventedbydrawingairoutofpotentialpocketingareasintothefansuction.Bothairrecirculation/hydrogenskimmertrainshaveanairrecirculationfanlocatedatEl.629'ntheuppercontainment.Eachsystemhasatotalcapacityof41,800cfm.Thefansdischargeviatheannularspacebetweenthecranewallandthecontainmentlinerintothelowercontainment.Bothtrainsareautomaticallyactuatedbythehigh-highcontainmentpressuresignalafteratenminutedelay.Thisdelayistoallowthetransientoftheinitialblowdowntocomplete.

UPPERVOLUMEPOLARCRANETOPDECKVENTDOORSICECONDENSERDOMESKIMMERIOOOSCFMLOWERVOLUME(HYDROGENSKIM)ERI800SCFMELECTRICHYDROGENRECOMBINERVENTILATIONUNIT~~ToiF0'k'LOWERCOMPARTMENTANDICECONDENSERDOORS300SCFMFROMFAN8INSTRUMENTROOMS~tFANSK~EasXKECA!RIDg~~gyggggeOsg~reCa<IOOOSCFMFROMDOME1500SCFMFROMPRESSURIZER8STEAMGENERATORENCLOSURES39,000SCFMFROMUPPERCOMPARTMENTTHROUGHORIFICEPLATEToINTAKEPLENUMMOTOROPERATEDVALVEtsh~.PRESSURIZER~ENCLOSUREPRESSURIZER'r,ICECONDENSERDOORI~IIP~~~~IIIII~,~%~~it~~IIIIII1IIr~~STEAMGENERATRFANIINTAKEPLENUM',~~NOTE:ACCUMULATORNOTSHOWNFORCLARITYp~LOWERCOMPARTMENTIANNULARREGION)tVIEW'A"t~~'a'I~~~SEEVIEWAMOTOR~~~\g~V~~~~FROMLOWERVOLUMEVENTILATIONHOLESASPERVIEWA~~~~~~~~tREACTOR~~~~~~~~~~~~~~LOWERVOLUMEINDIANA8MICHIGANELECTRICCO.DONALDC.COOKNUCLEARPLANTSRIDGMANMICIIIGAN9SOSOSO333-FLOWPATHOFTHECONTAINMENTAIRRECIRCULATION/HYDROGENSKIMMERSYSTEMUNITND.IOR2Figure4.1-1AirrecirculationflowpaththroughD.C.Cookicecondenser.(Ref.FSARFig.5.5.3).

fL~"lc~4i)Qf:)v-~0 (A)UpperCompartmentYa-745,896ft-A=1326ftA=osaftYrcleeCondenserA=24ft(D)AnnularCompartmentsVo.=61,702ftpperPlenum>Vu=54988ft(I)IceCondenser3Vl-126,878ftA=1000ftYA=302.1ft(B)LowerCompartmentVB-306,800ftAnnulus'unnelA=168ft2(C)CavityV.=16339ftFigure4.1-2D.C.Cookcontainmentvolumesandflowpaths.

• IICI0ItIIIIIBXLeel~KVCLCKNZcttrSQXRZACIORCDIITAIICCENTItILI~II~II'OVNITYREFVEUNO'MATERSTORASETANKILLICCIILOIIORINCIICADCILSSKKSIC.'M<TORIWCiREADERSSCKSK'A9LOwERCOvlPARTM&4TIIIIIJIIII1tIIIFKOIIRCSICVAIIIEATRCNOcALSYSTEMSCEOWCI5%lS~RlNozzLKTCEr<CCWCCZIONS(2)CONTAINMENTSPRAYHEATEKCNANEERsTOAPRONESSCNflALSKINICEwaYKRSUPPLYNEAOERSKCOwc'LSCISCALIIiIAllisl~ICKCONDEIISERIIIIIIIISKETCHM-ITYPLCALARRANGEMENTOFASINGLEVPPKRCOMPARTMENTSPRAYO'EADER(TWO(Z)CONTSPRAYANDYYIO(Z)RRR)~~YWuuCRSTYPICALFORFANROOMNISSILESARRIERIRIS.CPFICAIECOLAQOCLCWOER,SEEOwO59tT.~IICCIRCVLATIONLVIETIICAASAFETYllUKtZIDNRIM~A%SCKDWGSKCZroSAIKITOISCOONPIAIPSSEEPWCaSTCZRERRLIIICIWATERCEIVDLSEECW(a.SEi5,TOEIJSKiBZY(ZRRSEEVBZKHhTO'IIARCIEICiESEZES>SFROI(EszzzocTOCCACITZBCÃGD?QRKK$CEPWO.&STrtOIASPENTCVCLPITSYSTELI5CKOW55TSCTESTLIVELaNITROGQISUPPLYTovwl'It'ItTANISPRAYACTIVETANCSIAIEMVRECAlR9@g~AeghbteGsAperture~TYPKALFORISPRAYIICR5.ICZDKCDNIADDREIrSIRAYIKATEXCIIAIICiERSEETIESOWCI.O/CLCCROIAcccIIxssKQTSPRAYIKAT)KYOIACIDa.SEATRK'iD%5PVLTYPKALARSRKTCMA.9SCNCNATICARRSTOFLOPERCDMPARtMKEZTSL?RKYREADERSIiCN~CWCCIICAIICLCCllnCCC.DONALDC.COOK~IAAIIT~IOekNCONTARCAAENTSPRAYUNITN-IOR2~ILWI9C~ILICICICWet%ICNCCICIP.JULYI98Z.Figure4.1-3D.C.Cookcontainmentspraysystem,takenfromFSARFigure6.3-1.?

5pI'gE;~,C~Qa~7~CllAa$Qk, 42HantModehandMethodsforPhysicalProcessesTheCookNuclearHantcontainmentandsourcetermanalysesarepartofatraditionallevel2PRAanalysis.Theanalysiscouplesaprobabilisticassessmentofcontainmentresponsetopostulatedinitiatingeventswithaphysicalmodelwhichexaminestheplantresponseandaddressestheimpactofphenomenologicaluncertainties.Sinceassumptionsregardingkeysevereaccidentphenomenamaydictatetheanalysisoutcome,dueconsiderationofphenomenologicalissuesisacornerstoneofthepresentapproachtothecontainmentandsourcetermanalysis.TheIPEaddressesthephenomenologicalissuesthroughplantspecificphenomenologicalevaluationsandsensitivitystudies.Thistwo-prongapproachprovidesaboundingassessmentofsourcetermreleasetimingandmagnitude.Thephenomenologicalevaluationstudiesaretheprinciplemeansofaddressingtheimpactofphenomenologicalissuesonplantresponse.Theresultantpapersaddressawiderangeofphenomenologicalissuesandprovideanin-depthreviewofplant-specificfeatureswhichinfluencetheconsequencesofsuchphenomena.Thephenomenologicalevaluationsummariesaresupportedbyinformationandexperimentalresultsavailablefromopenliterature.Thesepapersinvestigateboththelikelihoodofoccurrenceandtheprobableconsequencesofkeysevereaccidentphenomena.Thesummarypapersprovideatechnicalbasisfordevelopmentofthecontainmenteventtrees.Theresultsofthephenomenologicalevaluationsummariesaredescribedinthesubsectionsbelow.TheModularAccidentAnalysisProgram(MAAP)Revision3.0version17.02(Reference13)isusedintheCookNuclearPlantIPEtoprovideanintegratedapproachtothemodellingofplantandcontainmentthermalhydraulicresponseandfissionproductbehaviorduringsevereaccidents.TheplantphysicalmodelisdefinedinaMAAPparameterfilewhichprovidesMAAPwithinformationrequiredbythecodetoperformcalculationsofplant-specificfissionproducttransportandthermalhydraulicresponsetopostulatedaccidentsequences.TheparameterfiledevelopedfortheCookNuclearPlantprovidesacomplete,realisticdescriptionoftheplantforMAAPsimulation.Thedatawithintheparameterfiledescribingthecontainmentandprimarysystemconfigurationremainsunchangedforallaccidentsequences.Sensitivitystudiesareusedtodeterminewhichphenomenologicalissueshaveasignificantimpactonthelikelihoodortimingofcontainmentfailureandthemagnitudeofthesourcetermrelease.ThesesensitivitystudiesareconductedbothwithinthephenomenolgicalevaluationpapersandbyMAAPcalculations.InperformingMAAPcalculations,severalmodelparametersareinvestigatedwithrespecttotheinfluencesofmodelinguncertaintiesontheradionuclidesourceterms.Inparticular,uncertaintiesinthevariousphysicalprocessesareconsideredasdocumentedintheIDCOR/NRCissueresolutionprocess.ThevariousphenomenaandtheuncertaintiesaredescribedinlettersfromT.SpeisoftheNRC(References49,50,51).References9and20alsoprovidesummariesofthoseparametersthathavebeenjudgedtohaveasignificanteffectoncontainmentfailureandsourceterms.AdditionalguidanceonsensitivitystudiesisprovidedbyEPRI(Reference52).Theprobabilisticmodelsareembodiedincontainmenteventtree(CET)describedinSection4.4ofthissubmittalandthelevel1accidentsequenceeventtreesdescribedinSection3.1above.Resultsobtainedwiththeprobabilisticandphysicalplantmodelsarecloselylinked.Forinstance,theCETstructuredependsonMAAPanalysesto1)defineeventtreesuccesscriteria,2)establishtimingofkeyeventsforunderstandingofsequenceprogression,and3)determinetheaccidentsequenceoutcomes.Furthermore,sequencesdemonstratedbythequantificationtasktobedominantcontributorstotheoverallcoredamagefrequencybecomethebasisforMAAPcalculationsinsupportofthesourcetermanalysis.Finally,MAAPanalysesandphenomenologicalevaluationsummariesareusedtoinvestigatetheeffectofphenomenological uncertaintiesonthesourcetermassessment.TheuseofMAAPasdescribedabovep'rovidesthenecessarydeterministiccomplementtotheprobabilisticanalysis.AdetaileddiscussionofthecontainmenteventtreemodelsisprovidedinSection4.4ofthissubmittal.Hant.speciTicphenomenologicalevaluationshavebeenperformedinsupportoftheCookNuclearPlantIPEinordertodeterminethelikelihoodofallpostulatedcontainmentfailuremodesandmechanismsidentifiedinReference20.ThesedetailedevaluationswereperformedtosystematicallyaddressthecontrollingphysicalprocessesspecifictotheCookNuclearHantconfiguration.Theresultsoftheseevaluationsaresummarizedbelow.4.2.1ContainmentOverpasaaindionAplant-specificstructuralanalysishasbeenperformedfortheCookNuclearPlantcontainment(Reference60)todetermineitsultimateinternalpressurecapacityanditsmostlikelyfailurelocations.Thedominantfailuremodewasidentifiedasbendingshearfailureinthereinforcedconcretecontainmentbasematadjacenttothereinforcedconcretecylinderwall.Themedianpressurecapacityatthislocationwascalculatedtobe57,8psig,withthetotalvariabilityfromrandomnessanduncertaintyof0.14and0.14respectively.In1991,thepotentialfailureofthecontainmentbasematwasreassessedusi:.:"asis"materialproperties.Becausetheuncertaintiesinmaterialpropertieswerereduced,themediancapacityforthislocationincreasedto66.5psig.Themedianfailurepressureforthepersonnelaccesshatch,equipmenthatch,andconcretecylinderare80.2psig,78.4psig,and84.0psig,respectively(Reference60).Figure4.2-1illustratesthecontainmentfragilitycurve,orcumulativeprobabilitydistributionfunction.Thebasemat/cylinderjunctionisthedominantfailurelocationfortheCookNuclearPlantcontainment.Thepressurecapacitythatisexceededwith95%frequencyat95%confidence,consideringbothinherentrandomnessaboutthemeanandtheuncertaintyinthemeanitself,is36psig(50.7psia).Thisvaluewasusedforcomputingcontainmentfailureinthelevel2analysis.Thereanalysisofcontainmentultimatecapacitycompletedin1991calculatedaHCLPFfailureof45.8psig.WVhiletheuseofeitherthemedianfailurepressureorrevisedHCLPFfailurepressurewouldprovideadditionaltimebetweencoremeltandcontainmentfailure,thisadditionaltimewouldhaveonlyaminorimpactonthesourcetermanalysis.Thevalueof36psigwasusedbecausetheanalysishasbeenpreviouslysubmittedandreviewedbytheNRCstaKUncertaintiessurroundingtheexactcontainmentfailuresizeandlocationarediscussedandaccountedforinthesensitivityanalysisofSection4.7.4.2DContainmentIsolationFailureContainmentisolationfailureisapossiblecontainmentfailuremodeattheCookNuclearPlant.Containmentisolationfailurereferstomechanicaloroperationalfailuretoclosecontainmentfluidsystempenetrations,whichcommunicatedirectlywiththecontainmentortheprimarysystem.Thisfailuremayoccurpriortoorshortlyfollowing,theinitiationofcoredamageandwouldimpairtheabilityofthecontainmenttolimitfissionproductreleasetotheauxiliarybuildingortheenvironment.Containmentisolationwouldfailononeormoreofthefollowingconditions:1)Afluidlineormechanicalpenetration,whichisrequiredtobeclosedduringpoweroperation,hasbeenleftunisolated.2)Afluidline,whichhasisolationvalveswhicharerequiredtocloseonanisolationsignal,failstodose,or3)Afluidline,whichispartofasafetysystemandisrequiredtoremainopenfollowingthegenerationofisolationsignals,isnotdosedbytheoperatorsifthesystemis"failed"ortheoperationofthesystemisterminated.e-Inalloftheaboveconditionsforfluidsystems,allvalvesinfluidlinesmustalsofailtodoseinorderforimpairedcontainmentisolationtooccur.Forexample,ifalineisprotectedbytwomotoroperatedisolationvalvesandonecheckvalve,allthreemustfailtodose(possiblydifferentfailuremodes)tocreateanunisolatedcontainmentcondition.Failureofcontainmentisolationwasconsideredforlineswhichmeeteachofthefollowingscreeningcriteria:I)thelinepenetratingcontainmentdirectlycommunicateswitheitherthecontainmentatmosphereorthereactorcoolantsystemanditisnotpartofadosedsystemoutsideofcontainmentcapableofwithstandingsevereaccidentconditions.2)thelinepenetratingcontainmentisgreaterthan2inchesindiameter.4.2BContainmentBypassContainmentbypassisanotherpossiblefailuremodefortheCookNuclearPlant.Containmentbypassreferstofailureofthepressureboundarybetweenthehighpressurereactorcoolantsystem(RCS)andalowerdesignpressurelinepenetratingcontainment.Thisresultsinadirectpathwayfromthereactorcoolantsystemtotheauxiliarybuildingortheenvironment,bypassingthecontainment.ContainmentbypassisusuallyconsideredasanaccidentinitiatorthatcanleadtocoredamagebecausethelossofcoolingfluidtoalocationoutsidecontainmentprohibitstheuseofECCSrecirculationforlonftermcorecooling.Thelikelymechanismsforthisfailuremode,identifiedfortheCookNuclearPlantasbeingsignificantintermsofbothfrequencyandpotentialconsequences,are(I)aninterfacingsystemsLOCAand(2)asteamgeneratortuberupture.4.2.4DirectContainmentHeating(DCH)TherelevantexperimentsforDCHhavebeenreviewedandhaveproducedonespecificconclusion:giventhenecessaryRCSconditionsforhighpressuremeltejection,containmentstructures(geometry)haveafirstorder(dominant)mitigatinginfluenceonthepotentialforDCH.Mechanisticmodelsfordebrisdispersal,whichtakeintoaccountentrainmentfromthecavityandd~ntrainmentatthetunnelexitwereusedtoevaluatethecontainmentresponsetoahighpressuremeltejection.Theevaluationofdirectcontainmentheatingshowstheresultingpressurizationexpectedduetothisphenomenawouldbewellbelowavaluethatwouldchallengecontainmentintegrity.DCHisnotconsideredasacontainmentfailuremodefortheCookNuclearPlant.4.2.5SteamExplosionsSeparateapproachesareusedtoaddressin-vesselandex-vesselsteamexplosions.TheIDCORwork,whichisconsistentwiththerecommendationoftheNRCsponsoredSteamExplosionReviewGroup,formsthebasisforthetreatmentofin-vesselsteamexplosions.Resultsofanalysesperformedinaccordancewithsignificant-scaleexperimentsandexpansioncharacteristicsofshockwavesformthebasisforthetreatmentofex-vesselsteamexplosions.Itisconcludedthattheslumpingofmoltendebrisintothereactorpressurevessel(RPV)lowerplenumcouldnotresultinsufficientenergyreleasetothreatenthevesselintegrityandhencewouldnotleaddirectlytocontainmentfailure.Likewise,evaluationsofboththesteamgenerationrateandshockwavesinducedbyex-vesselexplosiveinteractionsshowthatthesewouldnotbeofsufficientmagnitudetothreatenthecontainmentintegrity.

4.2.6MoltenCoreZoncreteAttackMoltencor~oncreteattackwithintheCookNudearPlantreactorcavityisevaluatedforthemostsevereaccidentsequence(i.e.,alargeLOCAwithoutRWSTinjection)usingasimple,boundinganalysismodelwhichassumesthattheconcreteablationrateisproportionaltothetotalheatgenerationrateduetodecayheatandchemicalreactions.Themodelusesempiricalparametersdeterminedfromavailableexperimentaldata.Theevaluationindicatesthatmelt-throughofthecontainmentbasematwouldnotoccuruntilwellbeyondthe24hourmissiontime.Furthermore,containmentfailureduetooverpressurizationwouldoccurlongbeforebasematmeltthrough.Therefore,moltencore-concreteattackisnotalikelycontainmentfailuremodefortheCookNuclearHant.42.7TheramlAttackofContainmentPaii~tionsThephysicalconfigurationoftheCookNuclearPlant'sicecondensercontainmentisthatthereareverydistinctcompartmentswithinthecontainment.Thiscompartmentalizationresultsinallmechanicalandelectricalpenetrationsbeinglocatedwithintheupperandannularcompartments.Anevaluationofdebrisdispersalrevealsthatthemajorityofentraineddebriswouldbed~ntrainedattheturnwithintheinstrumentationtunnelexit,whiletherestwouldbeconfinedwithinthelowercompartmentregionevenforahighpressuremeltejection.Thisispostulatedduetothephysicalconfigurationofthereactorcavityandbecausetheinstrumenttunnelhasalargeopeningtothelowercompartmentbutissealedtotheannularcompartment.Thereare,therefore,nodirectpathsbywhichcoriumcould'contactanycontainmentpenetrations.Theoperationallimitofthenon-metallicmaterialsareshownnottobeexceededbythemaximumgastemperaturespredictedforcontainmentcompartmentregionsduringsevereaccidentsequencesandtherewerenolocationsidentifiedduringthecontainmentwalkdownswherestandinghydrogenflameswouldbeexpectednearpenetrations.Hence,thermalloadingofpenetrationnon-metallicmaterialswouldnotcausedegradationandleakagefromthecontainmentunderconditionsexpectedinthecontainmentduringasevereaccident.42.8VesselThrustForce)TheboundinganalysisforthemagnitudeofthethrustforcewhenmoltencoredebrisisejectedfromthefailedreactorathighpressureindicatesthatthisforcecannotliftthedeadweightofthevesselitselfgivenacrediblebreaksizeintheRPV.Thelikelihoodofvesselthrustforcecausingthereactortoshiftitspositionisthenhighlyunlikely.Evenifthevesselcouldshift,theCookNuclearPlantcontainmentisconfiguredsothatreactionforcescannotbetransmittedtothecontainmentwall.Therefore,thispostulatedfailuremodeisboundedbytheplantdesign.4.2.9HydrogenCombustionPotentialdetonabilityandflammabilityoftheCookNuclearPlantcontainmentatmosphereareevaluatedaspart'oftheIPE.Detonationwasevaluatedbasedonbothgeometricconfigurationanddetonationcellwidthscaling.,Bothofthesemethodsconcludedthatthelikelihoodofdeflagrationtodetonationtransition(DDT)isverylowandwasnotconsideredafailuremodeintheanalysis.Itisfarmorelikelythatcombustiblegaswouldbeconsumedwithincontainmentbydeflagrationratherthandetonation.Deflagrationofhydrogenwasevaluatedtodeterminewhethertheresultingpressurerisewouldbesufficienttochallengecontainmentintegrity.Thefirststepinthisevaluationwastodeterminethemassofhydrogenrequiredtoproduceapressurerisesufficienttocausecontainmentfailure.Thentheconditionsrequiredtoachievethisamountofhydrogenwereexaminedtodetermineifsuchascenariowasprobable.Theresultsoftheevaluationshowed,thatevenforatotalstationblackoutattheCookNuclearPlant,aworstcasesequencewithrespecttohydrogencombustion,itisunlikelythatenoughhydrogenwouldaccumulatetoproduceadeflagrationthatcouldchallengethecontainmentultimatepressurecapacity.Furthermore,ifascenariodidexistwhichcouldproduceahydrogenburnofsufficientmagnitudetofailthecontainment,it4-10 ismuchmorelikelythatthecontainmentwouldhavefailedduetoslowoverpressurizationwellbeforesuchalargeamountofhydrogencouldaccumulate.Noneofthesequencesaddressedinthecontainmentandsourcetermanalysiscouldrealisticallythreatencontainmentduetohydrogencombustion.Hydrogencombustion,therefore,isnotconsideredafailuremodeoftheCookNuclearPlantcontainment.BecausehydrogencombustionisnotalikelyfailuremechanismfortheCookNuclearPlant,itwasconcludedthatabackuppowersupplyforthehydrogenigniterswouldprovidenonoticeablebenefitinreducingthefrequencyorconsequencesofcontainmentfailure.4.2.10Summa'nsummary,theapproachtotheassessmentofcontainmentresponseadoptedintheCookNuclearPlantIPEprogramlinkstogetherprobabilisticmodelsintheCETwithphysicalplantmodelscontainedinMAAP.Thesemodelsaresupplementedthroughtheuseofplantspecificphenomenologicalevaluationstoprovidein-depthtechnicalargumentswhichreducephenomenologicaluncertaintiesandexaminerealisticplantresponsetosevereaccidentphenomena.TheevaluationsofthephenomenologicalissuesandtheirpotentialimpactonthesourcetermanalysisaresummarizedinTable4.2-1.4-11 Table4.2-1PHENOMENOLOGICALEVALUATIONSUMMARIESONPOSTULATEDCONTAINMENTFAILUREMODESFAILUREMODE1.HydrogenCombustion2.DirectContainmentHeating(DCH)PHENOMENAIn-vesselH>generationEx-vesselHzgenerationSteaminertingAutoignitionRPVfailureDebrisdispersionInfluenceofcontainmentstructuresHydrogencombustion/steaminertingISSUE/FAILUREMECHANISMBreachcontainmentbyoverpressurizationduetoHzburnordetonationEarlybreachofcontainmentbyrapidoverpressurizationMAJORUNCERTAINTYAmountsofH>andCOFlammabilityofcontainmentatmosphereDegreeofdispersalincontainmentHydrogencombustionEnergyabsorptionbyicecondenserIMPACTNoearlycontainmentfailureLongtermcontainmentfailurepossibleifinappropriaterecoveryactionContainmentpressuresforDCHfarlessthanultimatestructurecapability3,SteamExplosionsRapidsteamgenerationShockwavesEarlycontainmentoverpressurizationandbreachThermalexchangewithentireairspaceMissilegenerationMissileimpactOccurrenceofmultipleconditionsrequiredtoproducelargescalesteamexplosionNothreattoRPVorcontainmentPromotesdebrisdispersalandcooling4-12 Table4.2-1(Continued)PHENOMENOLOGICALEVALUATIONSUMMARIESONPOSTULATEDCONTAINMENTFAILUREMODESFAILUREMODEPHENOMENAISSUE/FAILUREMECHANISMMAJORUNCERTAINTYIMPACT4.MoltenCore-ConcreteInteractions(MCCI)5.Vessel"Blowdown6.ThermalLoadingonPenetrationsConcreteablationanddecompositionGasevolution(Hz,CO,C02)DebrisspreadingH>recombinationRPVruptureRPVthrustforcesRPVrestraintsDegradationofnon-metalliccomponentsBasematpenetrationafterseveraldaysofattackFailureofcontainmentpenetrationlinesconnectedtoRCSContainmentbreach;leakagepathPresenceofwatertoquenchdebrisDebriscoolabilityRPVfailureandfailuresizeMagnitudeanddurationofelevatedcontainmentgastemperatureBehaviorofnon-metallicmaterialsathightemperatureOverpressurizationwouldoccurbeforebasematpenetrationBasematpenetrationyieldsa"buried"FPreleasepathNoorlimitedRPVdisplacementChallengeboundedbydesignbasisNolossofcontainmentintegrityexpectedPotentialforlongtermlossofelectricalfunctionality4-13 Table4.2-1(Continued)PHENOMENOLOGICALEVALUATIONSUMMARIESONPOSTULATEDCONTAINMENTFAILUREMODESFAILUREMODEPHENOMENAISSUE/FAILUREMECHANISMMAJORUNCERTAINTYIMPACT7.Over-pressurization8.ContainmentIsolationFailure9.ContainmentBy-passNoncondensiblegasgenerationSteamgenerationHzburnContainmentptpmgOperatorresponseSignaldependencyInterfacingSystemsSGTRContainmentbreachFPreleasepaththroughunisolatedp>pmgFPreleasepaththatdoesnotpassthroughcontainmentairspaceTlmlQg,size~andlocationofcontainmentbreachFPplateout/pluggingFPdepositioninbuildingoutsidecontainmentNumberofrupturedSGtubesFPreleasetoenvironment(airorsoil)orotherbuildingsLowprobabilityofdirectFPpathtoenvironmentorauxiliaryLowprobabilityofdirectFPpathtoenvironmentorauxiliarySizelocationofbreakoutsidecontainmentWaterscrubbingatbreaklocationFPdepositionoutsidecontainment4-14 COOlCFAILUREPRESSURE95/95CQNFIDENCF0TOTAL~BASENATml-CDCLCDolAQoLdCtCCiJ~.IILIIIIIIIIIILIIIIIIIIIIIIILIIIIIIIIIIIIIIIIIIIIIIIIII-~~IIIIIIIIIIIIIIIlIIIIJIIIIIIIIIJIIII2030805060CONTAINMENTPRESSUREPSIG7080Figure4.Z-ID.C.Cookcontainmentfragilitycurveforbasematfailure.

0)0 4gContainmentFailureHant<pecific'phenomenologicalevaluations,summarizedintheabovesection,havebeenperformedinsupportoftheCookNuclearHantIPEtodeterminethelikelihoodofallpostulatedcontainmentfailuremodesandmecluuusnxsidentifiedinReference20.ThesedetailedevaluationswereperformedsystematicallytoaddressthecontrollingphysicalprocessesoreventsspecifictotheCookNuclearHantconfigurationandtheyareincorporatedintothesourcetermnotebook.Throughthephenomenologicalevaluationssummarizedintheabovesection,severalofthesevereaccidentphenomenaweredemonstratedtobeinconsequentialfortheCookNuclearPlantcontainmentsincethesincethepredictedpressuresresultingfromarealisticasses~mentofthesephenomenaarefarlessthanthecontainmentultimatestrength.Thephenomenaconsideredunlikelytoresultinfailureofthecontainmentare:hydrogencombustion,directcontainmentheating,steamexplosions,moltenureconcreteattack,thermalattackofcontainmentpenetrations,andvesselthrustforces.Themorelikelycontainmentfailuremodesarecontainmentoverpressure,containmentisolationfailure,andcontainmentbypass.Thesefailuremodesarediscussedinmoredetailbelow.40.1ContainmentOverpressureContainmentoverpressure,definedasafailuremodecausedbysteamingand/orgenerationofnonwondensiblegases,isapotentialcontainmentfailuremodefortheCookNuclearPlant.Dependingonthespecificaccidentsequencecharacteristics,overpressurefailuresmaybeobservedacross8'widerangeofeventtimes.Thepotentialforcontainmentoverpressurefailureexistsinsevereaccidentscenarioswheresufficientcontainmentheatremovalthroughsprayrecirculationisnotavailable.Overpressurefailureisexpectedtobeaslowmechanismsuchthatcontainmentpressurizationwouldbeapproachedgradually.FromtheevaluationdiscussedinSection4.2.1above,overpressurefailureisassumedtooccurat36psigatthebottomoftheannularcompartmentasaresultofashearfailureatthebasemat-cylinderjunction.Becausetheresultingstressesinthecontainmentstructuresareapproachedslowly,itisassumedthatarelativelysmallrupturearea(i.e.,"Leak-before-break"behavior)wouldbeinduced.Thisissupportedbythepublishedexperimentalevidenceforsteellinedconcretecontainmentstructures.,Atthetimeofcontainmentfailure,thereiswateraccumulatedinthelowerandannularcompartmentsasaresultoficemeltandRCSblowdown.IftheRWSTisinjected,morewaterwouldbeinthecontainment.Thepresenceofwaterinthelowerandannularcompartmentsnotonlypreventsimmediateairbornereleasefromthebreak,butalsoallowscontainmentpressurizationtocontinueuntilsufficientwaterisdischargedfromthecontainmenttoallownoncondensiblegasesandsteamtobereleasedfromcontainment.Ithasbeenassumedthatthecontinuedpressurizationofcontainmentwillbeataratewhichwillnotresultinanadditionalfailurelocationpriortoexpulsionofthewater.Inordertoestimateadelaytimebetweencontainmentoverpressurefailureandairbornefissionproductrelease,atimedelaymustbecalculatedandassumptionsmustbemaderegardingtheamountofwaterpresentandthesizeofthecontainmentfailure.Aonehourdelaytimefromcontainmentfailurewasassumedtoaccountforthetimerequiredtoexpelthewaterinthelowerandannularcompartments.AssumingaBernoullifIow,pushinga2x10slb,11fttallwaterpool,theapproximatemassandlevelofwaterexpectedincontainmentforsequenceswithRWSTirjection,througha5.6"holeunderpressureof50psiawouldtakeabout1hour.Thisonehourorlessofwaterdrainingtimeisaccountedforinthesourcetermanalysiscalculations.Theamountofwaterpresentineachsequencewillvarythetimeperiodaftercontainmentfailurewhenairbornereleasewouldbegin.InthesourcetermanalysissummarizedinSection4.7.thefollowingassumptionswereused.ForsequenceswithRWSTinjection,aonehourtimedelayfollowingcontainmentfailureisassumedpriortoanyairbornerelease.ForsequenceswithoutRWSTirjection,35minutesisassumedbecausetheonlywaterpresentincontainmentwouldbeduetoicemeltandRCS4-16 blowdown.Hence,inthecalculations,totallossofcontainmentwaterfromtheannularandlowercompartmentsismodeledaccordingtotheabovetimedelayfollowingthebasematfailure.Insummary,overpressurefailureoftheCookNuclearPlantcontainmentisassumedtoresultina5.6-inchequivalentdiameterholeinthecontainmentbasematasaresultofshearfailureofthebasematwylinderjunction.The0.17fthmholeallowswaterwhichhasaccumulatedinthelowerandannularcompartmentstobereleasedfromthecontainment.Afterinitialcontainmentfailure,atimedelay,whichvariesdependingontheamountofwaterpresentinthecontainment,isassumedpriortoanyairbornereleaseoffissionproductstotheoutsideenvironment.4BDContainmentIsolationFailureFortheCookNuclearPlant,ifalinepenetratingthecontainmentboundaryisnotisolated,themostlikelycauseoftheisolationfailurehasbeenidentifiedasafailuretodoseanadministrativelycontrolledmanuallyisolatedline.Thisimpliesthattheconditionsforisolationfailureexistpriortotheaccidentinitiation.Containmentisolabonisassumedtoresultinaten-inchequivalentdiameterpipewhichallowsdirectcommunicationbetweentheairspaceintheannularcompartmentandtheoutsideenvironment.Thislocationwaschosenbecausemostofthecontainmentpenetrationsarelocatedintheannularcompartment.Thelocationabovethecontainmentwaterlevelwaschosentodemonstratethedifferenteffectsofacontainmentfailureintheairspace.4BBContainmentBypassAsdiscussedinSection4.2.3,twopotentialcontainmentbypassaccidentswereevaluatedaspartofthelevel1analysis,steamgeneratortuberupturesandinterfacingsystemsLOCAs.Eachoftheseinitiatorsisevaluatedseparatelyinthesourcetermanalysis.FortheSGTRaccidentscenario,atuberuptureinvolvingadoubleendedruptureofasingletube(0.943sq.inbreakarea)isassumed.Thisrupturemaybefollowedbyareleasetotheenvironmentthroughthesteamgeneratorsafetyorreliefvalves.TheinterfacingsystemsLOCAaccidentscenariowasassumedtobeinitiatedbysimultaneousfailureoftwomotoroperatedisolationvalveswhicharethepressureinterfacebetweenthereactorcoolantsystemandtheRHRpumpsuctionpiping.ThesevalvesarelocatedinthecooldownpipingfromthelooptwohotlegtotheRHRpumps.Inthissequence,primarysystemfluidatfullRCSpressureispostulatedtopassintoalowpressuresegmentoftheRHRsystemwhereitcausesbothRHRpumpsealstofail.AnevaluationoftheRHRpumpsealsidentifiedanupperboundleakageareaof0.18ftzifbothpumpsealsfail(Reference47).ThisupperboundbreakareaisintherangeofamediumLOCA.HencearapiddepressurizationoftheRCSduetothelossofinventoryfromthebreakwouldbeexpectedforthisaccidentscenario.Thisbreakareaalsoconstitutesarelativelylargeareathroughwhichfissionproductsaretransportedoutofthecontainmentandintotheauxiliarybuilding.4.4ContainmentEventTrees(CETs)Theprimaryfunctionofthecontainmenteventtreeistoprovideasystematicmethodforreorganizingtheresultsofthelevel1accidentsequencequantiiflicationintoaformmoresuitableforsourcetermanalysis.ItisassumedpriortoentryintotheCET,thatcoredamageandvesselfailurehasoccurred.TheCETdescribesthecontainmentresponsetoacoremeltaccidentandaccountsforsysteminteractions,humanactions,andkeyphenomenologicalissuesbydefininafunctionalsetoftopeventsandtheirfailureandsuccessstates.EachcombinationoftopeventsuccessandfailurestatesthenleadstoauniqueCETendstatewhichprovidesinformationaboutex-vesselsequenceprogression,containmentstatus,andsourcetermrelease.Thus,theCETdescribestheaccidentsequencebeyondcoremeltandservesasadirectoryforbinningofsequencesinthesourcetermanalysis.4-17 ThestructureoftheCETisarrangedtofirstdeterminewhetherthecontainmentisimpairedduetoisolationfailure.Bypasssequences,whichreleasedirectlytotheauxiliarybuildingortheenvironmentviaECCSpipingorthroughthesteamgeneratorsecondarysidewithoutthebenefitofcontainmentfissionproductretentioncapabilities,weretreatedasalevel1initiatingeventand,therefore,arenotatopnodeontheCET.TheCETthendescribesRCSconditionsatvesselfailure.SpecificallytheCETdetermineswhetherthevesselfailsduetoahighorlowpressurecoremelt.ThedistinctionbetweenhighandlowpressurecoremeltaccidentsequencesisbasedonRCSpressureatthetimeofvesselfailure.ElevatedRCSpressureatvesselfailurewoulddrivethegasflowthroughthecavityregionwithsufficientvelocitytocausedebrisentrainmenttootherregionsofthecontainment.Thenextdecisionpointconsidersthestatusofthereactorcavity,i.e.,whethertheaccidentsequencehasresultedinawetcavityatthetimeofvesselfailure.ThisdecisioncanbedeterminedprimarilyonthebasisofRWSTirjectiontothecontainment,however,asdiscussedinSection4.1.1.1,thevolumeoftheRWSTalonemaynotbesufficienttofloodcontainmenttothelevelwherespillovertothecavitywouldoccur.Theimplicationofawetcavity,followingvesselfailure,involvesthepotentialforsourcetermscrubbinganddebriscoo!ability.Finally,containmentprotectionwasaddressedthroughnodaldecisionsregardingcontainmentspraysandhydrogencontrolsystems.Thestatusofthesesystemswasembeddedwithinthelevel1eventtreesandwasmaintainedwithintheCETsothattheseverityofthesourcetermreleasecouldbedistinguishedbetweenCETendstates.TheCETasdescribedaboveremainsapplicabletothosecaseswherecontainmentfailureoccurredpriortovesselfailure,Finally,toadequatelybridgetheLevel1and2efforts,thefollowingassumptionswereapplied:II~Coredamageunderlevel1leadstovesselfailure.~Thosesystemssuccessfulunderlevel1wereconsideredfunctionalunderlevel2,~Systemswhichfailedinthelevel1analysiswereconsideredfailedthroughoutthelevel2analysis.~Justificationforthebasisofthetimingofimportanteventsandoperatoractionswasdeterminedinthelevel1effort.4.4.1CETTopEventsandSuccessCriteriaThecontainmenteventtreedevelopedfortheCookNudearPlantIPEisdisplayedinFigure4A-1.TheCETtopeventsandtheirsuccesscriteriaaredescribedindetailinthesubsectionsthatfollow.4.4.1.1CordaimnentIsolationContainmentisolationreferstotheclosureofcontainmentpenetrationstolimitthereleaseofradioactivefluidsfollowinganaccident.Failuretoisolatedoesnotimplycontainmentfailurebutratherthatitsfunctionhasbeenimpaired.AssummarizedinSection4.3.2ofthissubmittal,themostlikelysingleeventwhichwillcausecontainmentisolationfailurehasbeenidentifiedasafailuretodoseanadministrativelycontrolledmanuallyisolatedline.Thisimpliesthattheconditionsforisolationfailureexistedpriortotheaccidentinitiation.Ascalarvalueforthefailureprobabilityofthiseventwascalculatedinthecontainmentisolationanalysis.Thisvalue,1.2xl0+,wasassignedtothisnodeduringCETquantification.4-18 TheimpactofsuccessorfailureofthisCETnodewasprimarilyonthetimingofsourcetermrelease.Afailuretoisolatecontainmentresultedinanearlyfissionproductsourcetermreleasefollowingtheonset'ofcoredamage.Thissourcetermreleasereceivesnobenefitfromlongterm,naturalfissionproductremovalmeduuuanssuchassettling.4.4.14HighPnssareMeltThepurposeofthisnodewastoallowquantificationofhighpressureversuslowpressurecoredamage.Forthosepostulatedsevereaccidentscenariosinwhichasubstantialpressurewasavailablewithintheprimarysystematthetimeofvesselfailure,highpressuremeltejectioncouldpotentiallydisplacecoredebrisintothelowercompartment.Entrainmentofdebrisbythesteam/hydrogenmixtureexitingthevesselandpassingthroughthecavityregionwasalsoapossibility.Debrisleavingthecavitywouldbedepositedinthecontainmentlowercompartmentasthekineticenergyoftheflowinggasesdecreasedandthecoredebrisbecamed~ntrained.Thegasvelocityrequiredtoentrainmoltendebriscanbecharacterizedbythevalueofthesuperficialgasvelocityrequiredforsupportingliquidfilms(Reference13).FollowingRPVfailure,thegasvelocityanditslikelihoodofexceedingthe"critical"velocityforentrainmentincreasewithincreasingRCSpressure.Thus,sequenceswhichresultinahighpressuremeltejectionfollowingRPVfailureexhibitvaryingdegreesofdebrisdisplacementandentrainmentfromthecavitytothecontainmentlowercompartment.Typicallowpressuresequences,suchasalargeLOCA,however,resultinallofthedebrisremaininginthecavityregion(i.e.,noentrainment).InadditiontotheRCSpressure,thedegreeofentrainmentisinfluencedbythecavity/instrumenttunnelgeometryandtheamountofmoltendebrispresentatthetimeofRPVfailure.Theplantdamagestatedefinitionforeachdominantcoremeltsequencefromthelevel1analysisincludedanindicationoftheRCSpressureatthetimeofcoredamage.Coupledwithadditionalknowledgeofthelevel1sequenceprogression,thisdefinedapriorithelikelihoodofahighpressuremeltejection(HPME)followingRPVfailure.Thus,thesplitfractionforthisCETnodewasspecifiedas0or1where0indicatesnoHPMEoccurs(i,e.,alldebrisremainedinthecavity)and1indicatedHPMEcouldoccur(i.e.,displacementandentrainmentofdebristothelowercompartmentwaspossible).Theoccurrenceofahighpressuremeltejectionaffectedcontainmentresponsebyinfluencinglongtennsequenceprogression.Italsoimpactedthesourcetermbyincreasingtheairbornefissionproductconcentration.Postulatedearlycontainmentfailuremodesresultingfromuncertaintiessurroundingvesselblowdownthrustforces,directcontainmentheating,andsteamexplosionswerediscussedanddiscountedinthephenomenologicalevaluationsummaries(Section4.2).TheimpactofHPMEonthelongtermcontainmentresponsewasduetotheresultingdebrisdistribution.Debrisdistributionaffectedtherequirementsformaintainingdebriscoolability,thedegreeofmoltencore-concreteinteractions,andthesteamingrateofcontainmentwaterpools.4.4.12RWSFIqjectionTheintentofthisnodewastodetermineifirjectionoftheRWSTtothecontainmentwassuccessfulpriortovesselfailure.RWSTinjectioncouldhavebeeneitherthroughtheemergencycorecoolingsystemsorcontainmentsprays.RWSTinjectioninfluencedthetimingoficedepletionandcontainmentfailure,andtherefore,directlyimpactedthesourcetermrelease.Systemsavailableforuseinthelevel2analysiswerealreadyaccountedforinthelevel1quantificationandareviewofthelevel1plantdamagestatewouldrevealthestateoftheRWSTinjectionontheCET.Thus,foraparticularsequence,anappropriatesplitfractionof0or1wasassignedtothisnode.SuccessoftheRWSTinjectionnodedelayedcor~oncreteattackandtheaccompanyinggenerationofaerosolsandairbornefissionproducts.Thus,theRCSirjectionnodewouldhaveastronginfluenceonthepotential4-19 radionuciidereleasefromcontainment.Successofthisnodewaspredicatedonthelevel1sequenceidentifyingirjectionintothecontainment.4.4.1.4ContainmentSprayIqjecbonandRecirculationThenexttwonodesdealwiththestatusofthecontainmentspraysystem.Thissystemprovidesforshorttermpressurecontrolandlongtermcontainmentheatremoval.Operationsofthesprayswouldcooltheatmosphere,condensesteam,andenhancesteamfiowthroughtheicecondenser.Thisprocesswouldalsotendtode-inertthecontainmentthusincreasingtherelativehydrogenandoxygenmolarconcentrations.Followingvesselfailure,sprayoperationwouldprovideapoolofwatertocoolthedebrisandscrubfissionproductreleases.Airbornefissionproductswouldalsobescrubbedbyspraystherebyminimizinganypotentialsourcetermrelease.Successofcontainmentsprayrecirculationisimportantbecauseofitslongtermcontainmentheatremovalrole.Theinteractionofcoredebriswithcontainmentwaterpools,mechanicalstructures,andatmospherecanresultinaheatupandpressurizationofthecontainment.Thepressurizationisafunctionoftherateofgasproduction(condensibleandnonwondensible),andtherateofincreaseofthecontainmentgastemperature.Sincethegasproductionandtemperaturerisecanbecharacterizedbythelevelsofdecayheatgenerationwithinthecoredebris,itisnecessarytoestablishsomeformofcontainmentheatremovalwhichmeetsorexceedsthedecayheatgenerationrates.Failuretoestablishanyformoflongtermcontainmentheatremovalwouldresultinsustainedcontainmentpressurizationandaneventualfailureatthecontainmentboundary.Thecontainmentsprayrecirculationnodeaccountsforthecontainmentresponseduetothesuccessorfailureofcontainmentheatremovalsystems.Failureofthisnodewillresultinafailureofthecontainmentduetooverpressurewhilesuccessofthisnoderesultsinmaintainingpressurewithinthecapacityofthecontainment.Duringthetimeperiodwhencontainmentintegritycanbechallengedduetooverpressure,thedebrisdecayheatlevelsaresufficientlylowsothattheoperationofonecontainmentspraypumpplusheatexchangercanadequatelyremovedecayheat.Thus,operationofonecontainmentspraytraininrecirculationwasrequiredforsuccessofthecontainmentsprayrecirculationnode.Thesplitfractionsforthecontainmentsprayinjectionorrecirculationnodesforaparticularsequencewere0or1dependingonthesystemavailabilityasdefinedinthelevel1plantdamagestate.4.4.1.5HydrogenIgnitasTheCookNuclearPlantcontainmentdesignincorporates70thermalignitersthroughoutvariouscompartments.Theintentoftheignitersistoprovideignitionofleanhydrogen-airmixturesthroughoutthecontainment,thusreleasingmoderateamountsofenergytothecontainmentoveranextendedperiodoftime.Operationoftheigniterswillminimizeanyrapidcontainmentpressurizationcausedbyhydrogenburns.Failureofthehydrogenignitersystemasinthecaseofastationblackoutwasassessedasanuncertaintyinaddressingtheimpactofhydrogenwithinthecontainment.Theamountofhydrogenandothernon-condensiblegasesgeneratedduringasequencewasconsideredaspartoftheuncertaintyanalysis.Successofthisnodeassumesonefunctionaltrainofhydrogenignitersoperatingfor48hours.Anappropriatesplitfractionof0or1wasassignedtothisnodebasedonlevel1sequencedefinition.4.4.1.6ContainmentRecira8ationFansThecontainmentrecirculationfansserveaprimaryfunctionofcontainmentairmixing.Thisisachievedbycirculatingairfromtheuppercompartmenttothelowercompartmentfollowinganaccident.Byvirtueofairrecirculation,thisprocessalsominimizesanylocalhydrogenconcentrationsbyuniformlydistributingthe4-'20 hydrogenthroughoutthecontainmentairspace.Operationoftherecirculationfansmayenhancehydrogenburningbycirculatingoxygentopreviouslyinertedareasofthecontainment.Thefailureprobabilityofthissystemwasquantifiedinthelevel1accidentanalysisand,therefore,anappropriatesplitfractionof0or1wasassignedtothisnodebasedonlevel1sequencedefinition.4.42CEl'tnxtureandEndStatesTheCETtopevents,asdescribedabove,werearrangedinamannerwhichdepictstheaccidentprogressionandprovidesappropriategroupingforsourcetermevaluation.Failureofcontainmentsprayinjectionwasassumedtoresultinfailureofsprayrecirculation.Inaddition,ifthehydrogenignitersoperatedsuccessfully,operationoftherecirculationfanswouldhaveonlyaminimalimpactontheoverallcontainmentresponseand,therefore,wasbypassed.Thelevel1plantdamagestatedescriptorconsistsofaseriesofalphabeticcharacters.Thefirstdepictsthecategoryoftheinitiatingevent,thesecondtheRCSpressure,andthethirdisaseriesofcharactersaddressingthestatusofprimaryprotectionsystems.ThesecharactersweredefinedinSection3.1.5ofthissubmittalandarereflectedinFigure4.4-1.Thecombinationoftopeventsresultedinthe25CETendstatesshowninFigure4.4-1.Utilizingthedefinitionsfromsection3.1.5,eachCETendstatewaslabeledwithanappropriateplantdamagestatedesignator.Toaddresslevel2results,adesignatordefinedandassignedassummarizedinSection4.7ofthissubmittal,wasaddedwhichdepictsthestatusofthecontainmentandsourcetermrelease.BasedontheanalysissummarizedinSection4,4.1,itwasconcludedthatendstatesidentifiedasHR(RCSathighpressure,containmentsprayinjectionandrecirculationsuccessful),HRI(HRandhydrogenignitersfail),LR(RCSatlowpressure,containmentsprayinjectionandrecirculationsuccessful),andLRI(LRandhydrogenignitersfail)wouldbesuccessfulinthatcontainmentfailurewillnotoccur.StatesHRIFandLRIFaresequencedependentandrequiredfurtheranalysisbeforeconcludingsuccessorfailureofthecontainment.ThebalanceoftheCETendstatesconstitutecontainmentoverpressurefailuresorisolationimpairments.0'ontainmentisolationisshownasbranchingdirectlytoatransfertree.Failuretoisolateprimarilyimpactedsourcetermreleasebyprovidingapotentialalternatereleasepathfollowingcoredamageorvesselfailure.FortheCookNuclearPlant,containmentisolationfailurewastreatedasaneventwhichwasindependentofanyinitiatororstatusoftopnodes.Therefore,everyCETendstatecouldalsoincludecontainmentisolationfailure.FollowingquantificationofCETeventswithsuccessfulisolation,dominantsequenceswerereviewedforevaluationofisolationfailure.4-21

'.::,'igh".':,::,::::.-:.;::Initiatai'::::Cont.Presstjre';:.,:)':,,"::;;:,".:.'::~';i~:Isolation':';-,;Melt(:.:,'-.:~',Ca'nt.i;-'ont.RWST.':;'::Sp'ray'.;SprayInjection'iijectionRecirc.Hydogen-=.IgiiitersCont.Recirc.Fans-GETEndStateFrequencyLevellofSequencEndStateNumber-HRI-Hp:--:-H-HW-HC-MC'":"'"'HCI'~-H-Hl--'HW:;--:,i..-'HWI".-""'-'R'-'-'.:@-HCIHCIF-HI-HIF-HWI-LRI-LRIF-LCL'CI"""""-LCI-LCIF-LIF-LW-LWI;".ii:;-;~."-LWI-LWIFTransferFigure4.4-1D.C.Cookcontainmenteventtree.4-22 4.5CETQuantificationCETquantificationwasperformedforthecoredamageaccidentsequencesfromthelevel1analysis.TheCETquantification,summarizedinTable4.6-1,assignedeachcoredamagesequence,alongwithitsfrequency,toaparticularCETendstate.Theseendstatesandthecumulativefrequenciesformedthebasisforgroupingsimilarsequencesintoaccidentsequencebins.QuantificationoftheCETwasperformedintwosteps.Thefirststepofthequantificationassumedthatcontainmentisolationwassuccessful.Thesecondstepofthequantificationaccountedforcontainmentisolationfailure.ThefirststepoftheCETquantificationwasperformedindividuallyforeachinitiatingeventcategory.Inthisstep,theprobabilitiesofCETtopeventsuccessandfailurestatesweredeterminedbythelevel1accidentsequencequantification.ThesplitfractionsforeachCETbranchwereassignedas0'sand1'sbasedonareviewofthelevel1accidentsequencedefinition.CETquantificationsimplyinvolvedfollowingtheCETbranchinglogicforeachlevel1accidentsequencetoarriveataparticularCETendstate.ThefrequencyofeachCETendstateisthenthesumofthefrequenciesofthelevel1accidentsequencesassignedtothatendstate.Thefailureprobabilityofcontainmentisolationwasnotcalculatedaspartofthelevel1accidentsequencequantificationbut,assummarizedinSection4.4.1.1,wascalculatedaspartofaseparateanalysistobe1.2E-04.ThecontainmentisolationtopeventintheCETisassignedthisvalue,1.2E-04,asascalar,InthesecondstepofCETquantification,theCETendstatesfromtheabovestepwerereviewedbyinitiatingevent.TheCETendstatewiththehighestfrequencyand,insomecasestheCETendstatewiththesecondhighestfrequency,wasselected.Thefrequencyofeachoftheseendstateswasmultipliedbythefailureprobabilityofcontainmentisolation.ThesequencewasthenworkedthroughtheCETasabove.TheseresultingCETendstateswererankedbyfrequencyandscreenedforuseinthesourcetermanalysis.TheeffectsoncontainmentweredeterminedbyMAAPanalysis.TherankingandscreeningprocessandMAAPanalysesaredescribedinthefollowingsections.4.6BinsandHantDamageStatesTheresultsofthelevel1analysismustbeprocessedintoaformmoresuitableforsourcetermanalysis.ThefirststepinthisprocessingistheCETquantificationdescribedinthesectionabove.Theremainingprocessinginvolvedgroupingsimilarsequencesintoaccidentsequence"bins"toreducethetotalnumberofsequencesanalyzed.Sourcetermquantificationcouldthenbeperformedbyanalyzingasingle,representativeaccidentsequencefromeachbin.Thebinningprocessusedforsourcetermanalysiscanbesummarizedasfollows:(A)Screeningprocess:FromtheresultsoftheCETquantification,acertainnumberofCETendstateswasselected.TheseCETendstateswereselectedbasedonthesequencescreeningcriteriaguidelinesgiveninReference20.(B)Sequencebinning:TheCETendstatesidentifiedaboveweregroupedsuchthateachgroupwouldresultinsimilarsourceterms.(C)Selectionofrepresentativesequences:AtleastonesequencewasselectedfromthoseincludedwithineachgroupinstepB.Theselectedsequence(s)wereanalyzedforthesourcetermanalysis.(D)Releasecategory:FromthesourcetermresultsinstepC,areleasecategorywasassignedtoeachgroupidentifiedinstepB.Thesestepsaredescribedinmoredetailinthesubsectionsthatfollow.

4.6.1ScreeningProcessTheCETresultswerereviewed,tabulatedandorganizedaccordingtocoredamagefrequencywiththeresultslistedinTable4.6-1.Thesequencenumbersinthethirdcolumncorrespondtothesequencenumberfromthelevel1eventtrees.WhenseveralsequencesappearonthesamelineinTable4.6-1,thesequenceshavethesameinitiator(column1)andCETendstate(column2).Thecoredamagefrequency(column4)isthesumofallthefrequenciesforallthesequenceslistedontheline.Itisfromthislistingthatscreeningwasperformed.NUREG1335(Reference20),Section2.1.6describesthescreeningprocessforfrontedresults.ThefollowingcomparestheserequirementstotheresultstabulatedinTable4.6-1.NgR~E~1+5Table4.6-1Anysystemicsequencethatcontributes1E-7ormoreperreactoryearSequencesthroughline22ofTable4.6-1Allsystemicsequenceswithintheupper95%ofthecoredamagefrequencySequencesthroughline12ofTable4.6-1Allsystemicsequenceswithintheupper95%ofthetotalcontainmentfailurefrequencySystemicsequenceswhichcontribute1E4tocontainmentbypassInanycase,shouldnotexceed100mostsignificantsequencesSequencesthroughline23ofTable4,6-1Sequencesonline30needtobeincludedSequencesthroughline40ofTable4.6-10)Reportedinthissubmittalarethetop100accidentsequencesofthelevel1analysisasscreenedthroughtheCET.Linesonethrough40ofTable4.6-1included100accidentsequences.Inaddition,reportingthesesequencesexceedstheminimumreportingrequirementsofReference20.4.6.2SequenceBinningandSelectionofRepresentativeSequencesThebinningofthe40CETendstateswasbasedonaseriesofdecisionsthatresultedingroupingtogetherlikesequences.Thefirstgroupingofthescreenedendstateswasbasedonthestatusofcontainmentforthesequence.Thusallsequencesfallinitiallyintothefollowingstatus:~Containmentisolationfailure~Containmentbypassed~Containmentoverpressurelsuccess.Veryfewofthe40CETendstatesfellundertheimpairmentorbypassedcategories.Eachofthesecontainmentstatuscategories,therefore,wastreatedasaseparatebin.k Themajorityofsequencesfellintothecontainmentoverpressure/successstatus.Thus,severalbinswerenecessarytoaddressthesequenceswithinthiscontainmentstatuscategory.SourcetermreleasesforthesecategoriesdependonthetimingoFsucheventsasvesselfailure,icedepletion,andcontainmentfailure.Theavailabilityofwatertocoolthedebristhroughvesselorcontainmentirjectionwouldimpactthetimingoftheseevents.Toaddresstheavailabilityofwaterfordebriscooling,theCETandthetop40CETendstateswerereviewed.Thisreviewindicatedthefollowingfunctionalgroupingsformaintainingwaterwithincontainmentandthevessel:I.SuccessfulcontainmentsprayinjectionandrecirculationII.SuccessfulcontainmentsprayirjectionbutfailedsprayrecirculationIII.Failedcontainmentsprayinjectionandrecirculation.Thefirstgroupencompassesthosesequenceswithan"R"designatorasthethirdletterintheirCETendstatedescription.Thesecondgroupwouldisidentifiedbya"C"designatorasthethirdletterintheendstatedescription.Thethirdgroup'sdesignatorcontainsa"W"asthethirdletterinthedesignator.AfourthgroupwasidentifiedbythereviewoftheCET.ThisgrouphadsuccessfulRWSTinjectionthroughtheECCSbutfailedallcontainmentspray.Noneofthesequencesinthetop40CETendstatesfellintothisgroup,therefore,thisgroupwasnotconsideredforfurtheranalysis.SequencesinGroupIwouldresultincontainmentsuccess.Smallreleasesthroughprexistingnormalleakageleakagepathsmayoccur.Thisleakagewouldbewithinthelimitspermittedbytechnicalspecifications.GroupIIsequenceswouldhaveawaterpoolcoveringthedebrisejectedfromthevessel.Thiswaterpoolwouldcausecontinuoussteamingwhichwouldcausethequickestdepletionoftheicemassand,therefore,theearliestcontainmentfailure.GroupIIIwouldhaveresultedinadryreactorcavity,nosteamingofawaterpoolcoveringthecoredebrisand,therefore,thelatestcontainmentfailure.Thethreegroupsdiscussedabovearefurtherdividedintotwocategoriesbasedonreactorcoolantsystempressureatthetimeofreactorpressurevesselfailure.ThesplitofthegroupsintohighandlowpressurecategorieswasmadebyreviewofthesecondletterintheCETendstatedesignators.Thissplitresultsinsixbinsintowhichallsequencesotherthanbypassorisolationfailurewereplaced.Theinitiatorsforthelevel1workwerecategorizedasA(largeLOCA),S(smallLOCA),T(transient)andG(tuberupture).Eachofthesixbins,therefore,couldhavefourinitiators.LargeLOCAs,thoseendstateswithanAdesiginator,areonlylowpressureeventsbydefinitionandthereforewillnotrequireasplitbasedonpressure.Vesselfailurefortransientsandsteamgeneratortuberupturestypicallyoccursathighpressure.CETendstatesfortheseevents,therefore,werenotsplitintotwopressurecategoriesinordertosimplifytheanalysis.

Withtheassumptionsdescribedabove,thegroupsbecome:~IILZHlGROUPIII0,THRTHCGHCTHW~RJJ~PIQRROJI~PIIGROUPmALRSLRSLWThesixgroupsaboverepresentthebinsunderthecontainmentstatuscategoryofoverpressure/success.Allaccidentsequenceswithinthetop40CETendstateswhichwerenotcontainmentbypassorcontainmentisolationfailuresequencesfellintooneofthesebins.Thedesignatorsrepresentinitiator(firstletter),RCSpressure(secondletter)andavailabilityofwater(thirdletter).Oneormultiplesequencesareselectedfromeachgroupforfurtherevaluationinthesourcetermanalysis.Withineachinitiatorclassincludedinthegroupsabove(A,S,T,G),differentinitiatorsoccur.Forexample,transient(T)willincludeasinitiatingeventslossofoffsitepower,steamlinebreak,etc.Thus,inselectingaTHWsequence,morethanonecouldbeselectedbasedontheactualinitiator.Furthermore,inselectingsequencesfromclassG(SGTR),specialconsiderationmustbegiventowhethertheintegrityofthefaultedsteamgeneratorismaintained.ContainmentbypasstotheenvironmentwouldbeestablishedifasteamgeneratorPORV,safetyvalve,orMSIVonthefaultedsteamgeneratorfailstocloseorremainclosed.SGTRsequenceswereselectedtorepresentsituationswithandwithoutfaultedsteamgeneratorintegrity.0,ArepresentativesequencefromatleastoneoftheCETendstatesineachoftheabovebinswasselectedforsourcetermanalysis.Thesequenceselectedforanalysiswasoneofthetop100sequenceswhichweregroupedintothetop40CETendstatesofTable4.6-1.Thesequenceswereselectedforanalysisinordertoboundtheothersequenceswhichappearedinthatgroup.Thesequencesselectedforsourcetermanalysis(calledanalyzedsequences)aresummarizedinTable4.6-2.Theremainingsequenceswithinthetop40CETendstatesofTable4.6-1arecalledboundedsequencesandaresummarizedinTable4.6-3.Inadditiontoselectionofrepresentativesequencesfromthetop40CETendstateslistedinTable4.6-1,threeadditionalsequenceswereselectedforsourcetermanalysis,oneeachfrominitiatorsA,S,andT.Thesethreeadditionalsequences,indicatedinTable4.6-1,wereanalyzedwithfailureofcontainmentisolation.Noneofthesesequencesappearinthetop100list.Releasecategories,thelastletterintheCETendstatedesignatorofTable4.6-1aredefinedinTable4.6-4.FissionproductreleasecategorieswerecalculatedaspartofthesourcetermanalysiswhichissummarizedintheSection4.7ofthissubmittal.4.69ConclusionsThefrequencyofcontainmentoverpressurefailure,basedonthequantificationsummarizedabove,wascalculatedtobe2.08x10+peryear.Giventhatthecoredamagefrequencycalculatedbythelevel1analysisis6.26x10peryear,theconditionalprobabilityofcontainmentfailureonoverpressuregivencoredamageis3.3x10.Thefrequencyofcontainmentfailure,basedoninitiatorcategory,issummarizedinFigure4.6-1.0,4-26 Thisfigureshowstransienteventsarethemajorcontributortocontainmentfailure.~~TheCETquantificationindicatesthattherearethreemoorpathsthroughtheCETtocontainmentoverpressurefailure.ThesearefailuretoirjecttheRWST,failuretoinjectthroughcontainmentsprays,andfailuretoalignforrecirculation.Figure4.6-2illustratesthecontributiontocontainmentfailureforeachofthesesequences.Asshown,containmentfailureisdominatedbyfailuretoinjectandfailuretoalignforrecirculation.Thefrequencyofcontainmentbypassevents,ascalculatedbytheCETquantificationabove,is7.2x10+.Thisgivesaconditionalprobabilityofcontainmentfailuregivencoredamageof0.113.Themajorcontributorstocontainmentbypasseventsaresteamgeneratortuberuptures.InterfacingsystemLOCAs(V-sequences)contributelessthanonepercenttothisvalue.Failuretoisolatecontainmentcontributesonly0.01%totheconditionalprobabilityofcontainmentfailurewithafrequencyof6.52x109.4-27 TABLE4.6-1DONALDC.COOKNUCLEARPLANTDOMINANTSEQUENCELISTINITIATOR1.SLO2.CCW3.SLO4.SGR5.ATWS6.MLO7.MLO8.SGR9.SBO10.LLO11.ESW12.VDC13.SLB14.SBO15.SLO16.LLO17.VEF18.TRA19.TRS20.SLO21.LSP+22.TRS23.SLO24.SLB25.SGR26.LSPENDSTATESHR-STHR-SSLR-SGHR-CSHR-SSHR-SSLR-SGHR-TTHWIF-MALR-STHR-STHR-STHR-STHR-SSLC-JALC-JALR-STHR-STHWIF-MSHC-JTHR-STHR-S.SHWIF-MTHWWGHWIF-TTHWIF-MSEQUENCENO.13,23,322,12,22,41,50,1873,33,72,8230,39,48,67,8512,32,4122213,23,42,52,9150,80,130,1905,14,232,12,22,41,32,18613,22,312,32,41,71,121,172,1812,8,17,265,152126,353,133,134028,1950,9921FREQUENCY1.59x101.38x101.31x1055.99x10-62.79x10-62.29x10197xl0~9.98x1076.64x1076.33x105.96x105.85x1074.75xl074.68xl073.56x1073.16x1072.99x102.83x1071.77x1071.14x10l.lx1071.03x10991x10-88.48xl08673x10-8628xlo-8ANALYZEDSEQUENCES1350,1901813550214-28 TABLE4.6-1(Cont'd)DONALDC.COOKNUCLEARPLANTDOMINANTSEQUENCELISTINITIATOR27.ATWS28CCW29.MLO30.ISL31.MLO32.VDC33.CCW34.ESW35.VDC36.SLO37.CCW38.SLB39.TRA40.SLB41.SLO42.SGR43.LLO44.SLO45.SGR46.SGR47.SGR48.TRS49.MLO50.SLO51.SLO52.CCWTHR-S,THC-MSLC-JV-TSHWIF-MTHW-MTHWIF-MTHC-MTHC-MSHW-MTHW-MTHIF-MTHWIF-MTHC-MSL-JGHWIF-CALWIF-WSHRI-SGHW-TGHC-CGHC-TTHW-MSHC-MSH-MSHR'-ETHR'-ESEQUENCENO.2,11,215,15,1892,3,4,5,640205,15,50,189,19538191392311,41223,24,339,9745,941915,352913,23,322,12,22,41,32,186FREQUENCY5.82x10-s5.5xlos5.47xlo5.38xlo-s1.33xlo1.18xlol.12xlo-s7.41xl0~6.23xlo4.94xlo94.79xlo94.69xlo94.32xlo9.4.31xlo4.31xlo4.09xlo~3.98xl093.37xlO-92.68xlo92.68X1092.59XIO-92.53xlo2.12x102.02xlo91.91xlo1.66xlo9ANALYZEDSEQUENCES40354-29 TABLE4.6-1(Cont'd)DONALDC.COOKNUCLEARPLANTDOMINANTSEQUENCELISTINITIATOR53.SLO54.CCW55.ATWS56.TRA57.ATWS58.SGR59.LSP60.SGR61.VDC62.MLO63.ATWS64.MLO65.ESW66.ATWS67.LLO68.ATWS69.ATWS70.VEF71.MLO72.VEF73.MLO74.VDC75.MLO76.SBO77.LLO78.ESWENDSTATESLR'-ETHRIF-SSHC-MTHW-MSHW-MGHRI-CTHW-MGHR'-ETHRI-SSH-MSHWIF-MSHR'-ETHWIF-MSHRI-SALIF-MTHC-MSHR'-EALC-JSLR'-EALW-MSL-MTHWIF-MSHRI-STHWIF'WALR'-ETHR'-ESEQUENCENO.18833,512136199,184712,32,412031132430,39,48,67,852222950,80,130,1905,14,232,12,22,32,41,186FREQUENCY1.58xlo~1.49xlo91.22xlo91.18xlo91.16xlo9.27xlo8.45x10io7.18xlo6.22xloS.S6xlO-"S.OSxlO-"4Ssxlo4.73x10io4.3xloto4.03xlo3.64xlo3.35xlo'o2.7xlo2.36xlo1.78x10to1.49xlo-io1.48xlo'o1.38xlo7.97xlo"7.6xlo7.15xloANALYZEDSEQUENCES1904-30 TABLE4.6-1(Cont'd)DONALDC.COOKNUCLEARPLANTDOMINANTSEQUENCELISTINITIATOR79.VDC80.LLO81.LLO82.VEF83.SLB84.SBO85.LLO86.VEF87.TRA88.TRS89.LLO90.LLO91.LSP92.TRS93.VEFENDSTATETHR'-EALW-MAL-MALRI-STHR'-ETHR'-EALC'-UALR'-ETHR'-ETHWIF'WALRI-SALCI-VTHR'-ETHR'-EALWIF-WSEQUENCENO.2013,22,312,32,41,71,121,172,1812,8,17,265.15213,133,13FREQUENCY7.02x106.96x10"6.67x10'16.25xlo->>'.71x10"5.62x103.79x10"3.59x10"3.4x10"2.12x101.7x101.45x10"1.32x101.24x10"391X10-12ANALYZEDSEQUENCESLEGEND1.RefTable4.6-2fordefinitionofendstatereleasecategory.2.Coredamagefrequency=6.26x105.3.Primedsequenceendstatesdenoteafailuretoisolate.4.~Denotesupper95%ofcoredamagefrequency.5.+Denotesupper99%ofcoredamagefrequencySLO-SmallLOCAMLO-MediumLOCAESW-LossofessentialservicewaterSBO-StationblackoutTRA-TransientwithsteamconversionVEF-VesselfailureSLB-SteamlinebreakLLO-LargeLOCASGR-SteamgeneratortuberuptureCCW-LossofcomponentcoolingwaterATWS-Ant.tripwithoutscramLSP-LossofoffsitepowerTRS-TransientwitoutsteamconversionVDC-Lossofsingle250VDCtrain4-31 Table4.6-2ENDSTATESSELECTEDFORANALYSISGROUPI(H)I(L)DESCRIPTIONSuccessfulinjection&recirculationSuccessfulinjection&recirculationSHRGHRALRSLRTABLE4.6-1LINENotselectedbutboundedbyTHR2142148103ENDSTATETHRTHRTHRGHRGHRALRSLRINITIATORCCWSBOLSPSGRSGRLLOSLOII(H)II(L)III(H)Successfulinjection,failedrecirculationSuccessfulinjectionfailedrecirculationFailedinjectionandrecirculationSHCTHCGHCALCSLCSHWTHWGHW20NotselectedNotselected16152931925SHCALCSLCSLCSHWIFTHWIFGHWIFSLOLLOSLOMLOMLO)SGRIII(L)Nosequencesinthetop1004-32 Table4.6-3D.C.COOKNUCLEARPLANTBINNINGOFBOUNDEDSEQUENCESBOUNDEDANALYZEDINITIATORENDSTATERELEASECATEGORYINITIATORENDSTATERELEASECATEGORYLSPCCWSLOMLOATWSESWVDCSLBTRATRSATWSTRATRSLSPCCWSLOCCWVDCSLOSLBSLBCCWESWVDCSLOSLBVEFSGRFAULTEDS/GINTEGRITYMAINTAINEDSGRFAULTEDS/GINTEGRITYNOTMAINTAINEDTHRTHRSHRSHRSHRTHRTHRTHRTHRTHRTHRTHWIFTHWIFTHWIFTHWIFSHWIFTHWTHWSHWTHIFTHCTHCTHCTHCSLGHCGHCSSSSSSSSSSSMMMMMMMMMSBOSBOLSPSLOMLOSLOSBOLLOSGRSGRTHRTHWIFTHWIF1!SHCSHCSLCTHWIF'HRGHWIFMNOES:1.Ref.Table4.6-1forclarificationofboundedandanalyzedsequencenumbers.2.TheprimeinTHWIF'ndicatescontainmentisolationfailure.4-33 Table4.64RELEASECATEGORYDEFINITION0,ReleaseCateggrxDefinitionANocontainmentfailurewithin24hourmissiontimebutfailurecouldeventuallyoccurwithoutaccidentmanagementaction;noblegasesandlessthan1/10%volatilesreleased.BContainmentbypassedwithnoblegasespluslessthan1/10%ofthevolatilesreleased.Containmentbypassedwithnoblegasesplusupto1%ofthevolatilesreleased.Containmentbypassedwithnoblegasesandupto10%ofthevolatilesreleased.Containmentfailurepriortovesselfailurewithnoblegasesandlessthan1/10%ofthevolatilesreleased(containmentisolationimpaired).Containmentfailurepriortovesselfailurewithnoblegasesandupto1%ofthevolatilesreleased(containmentisolationimpaired).GContainmentfailurepriortovesselfailurewithnoblegasesandupto10%ofthevolatilesreleased(containmentisolationimpaired).HEarlycontainmentfailurewiththenoblegasesandlessthan1/10%volatilesreleased(containmentfailurewithinsixhoursofvesselfailure;containmentnotbypassed;isolationsuccessful).Earlycontainmentfailurewithnoblegasesandupto1%ofthevolatilesreleased(containmentfailurewithinsixhoursofvesselfailure;containmentnotbypassed;isolationsuccessful).Earlycontainmentfailurewithnoblegasesandupto10%ofthevolatilesreleased(containmentfailurewithinsixhoursofvesselfailure;containmentnotbypassed;isolationsuccessful).Latecontainmentfailurewithnoblegasesandlessthan1/10%volatilesreleased(containmentfailuregreaterthansixhoursaftervesselfailure;containmentnotbypassed;isolationsuccessful).4-34 Table4,64(Continued)RELEASECATEGORYDEFINITIONRelease~at~010DefinitinLatecontainmentfailurewithnoblegasesandupto1%ofthevolatilesreleased(containmentfailuregreaterthansixhoursaftervesselfailure;containmentnotbypasses;isolationsuccessful).Latecontainmentfailurewithnoblegasesandupto10%ofthevolatilesreleased(containmentfailuregreaterthansixhoursaftervesselfailure;containmentnotbypasses;isolationsuccessful).NLatecontainmentfailurewithnoblesgasesandupto1%ofthevolatilesanduptoI/10%ofthenon-volatilesreleased(containmentfailuregreaterthansixhoursaftervesselfailure;containmentnotbypassed;isolationsuccessful).Notused..Nocontainmentfailure(leakageonly,successfulmaintenanceofcontainmentintegrity;containmentnotbypassed;isolationsuccessful).Containmentbypassedwithnoblebasesandmorethan10%ofthevolatilesreleased.UContainmentfailurepriortovesselfailurewiththenoblegasesandmorethan10%ofthevolatilefissionproductsreleased(containmentisolationimpaired).VEarlycontainmentfailurewithnoblegasesandmorethan10%ofthevolatilesreleased(containmentfailurewithin6hoursofvesselfailure;containmentnotbypassed;isolationsuccessful).Latecontainmentfailurewithnoblegasesandmorethan10%ofthevolatilesreleased(containmentfailuregreaterthan6hoursaftervesselfailure;containmentnotbypassed;isolationsuccessful).4-35

')

SmallLOCA6.54x10LargeLOCA3.21x10Transients1.10x100+eeoe~Figure4.6-1Frequencyofcontainmentfailure(perreactoryear).4-36 FailToAlignREC)RCFailRNfSTInjection55%FailSpraylnjection1%Figure4,6-2Contributiontocontainmentfailure.4-37 4.7AccidentPagressionandRadionuclideReleaseCategorization4.7.1AccidentProgressionLossofcoolantfromtheprimarysystem,eitherthroughabreakinthecoolantboundaryoralossofheatsink(whichinturnpromotesover-pressurizationoftheRCSandsubsequentlossoffluidthroughthesafetyvalves),coupledwithfailuretoirjecttheRWSTintotheRCS,eventuallyresultsinuncoveringofthereactorcore.CoredamageoccursonceoxidationoftheZircaloyfuelcladdingbegins.ThisexothermicchemicalreactionbetweensteamandZircaloygeneratesheatandproduceshydrogen.Thereactioniscontrolledbytheavailabilityofsteam,whichcontinuestobegeneratedastheprimarysysteminventoryboilsoKThereactionrateaccelerateswhenthetemperatureoftheZircaloyexceeds2871'F(1850K),andthechemicalenergyreleasedatthispointinthetransientexceedsthelocaldecayheatgeneration.Coremeltbeginswhenthefueltemperaturereachestheeutecticmelttemperatureof4040'F(2500K).Asthecoremelts,moltenmaterialcandlesdownwarduntilitrefreezesoncoolermaterialbelow.Eventuallythismaterialre-meltsandmovesfurtherdownward,Thisdownwardprogressionismainlyafunctionofthetemperaturesencounteredbythemelt.Oncethemeltleavesthecoreboundaries,itbeginsattackingthecoresupportstructures.Largeholesinthelowercoresupportplateallowrelocationofthecoretothelowerplenumofthereactorvesselwithoutmeltingtheentirelowercoresupportplatestructure.IntheabsenceofexternalcoolingoftheRPV,relocationofthemoltencoreintothelowerheadisassumedtoleaddirectlytofailureofthereactorvessel.TheCookNuclearPlantIPEtooknocreditforpotentialin-vesselrecovery.IftheRCSisathighpressureatthetimeofvesselfailure,thenhighpressuremeltejection(HPME)couldpossiblydisplaceorentrainsomecoredebrisintothelowercompartment.Mostofthisdebrisisde-entrainedbylowercompartmentstructures.IftheRCSisatlowpressureatthetimeofvesselfailure,thenlowpressuremeltejectionresultsinonlyasmallamountofcoredebrisescapingthecavity.Ineithercase,ifsufficientwaterisalreadyavailableincontainmentpriortoRPVfailure,thenthecoredebrisisquicklyquencheduponexpulsionfromthereactorvesselintothecavityregion.Steamgeneratedduetoboilingthiswatermeltsthecontainmentice.Whentheiceisdepleted,thesteambeginstopressurizethecontainment.Ifcontainmentheatremoval(sprayrecirculation)isavailable,thecontainmentwaterpoolscanberecirculatedtocoolcoredebris.Ifnowaterisavailableorifthedebrisdrysout,thenmoltencore-concreteinteraction(MCCI)takesplace;thismostlikelyoccursinthereactorcavity.Concretedecompositiongeneratesnonwondensiblegasesandalsoreleasesasignificanamountofwaterfromtheconcrete.Thisadditionalwaterresultsinadditionalchemicalheatgenerationandhydrogenevolutionduetooxidationofmetallicconstituentswithinthemoltendebris.Thecontainmentcontinuestopressurizeduetoheatingofthecontainmentatmosphereandnon-condensiblegasgeneration.Ifnocontainmentheatremovalisavailable,thispressurizationinducescontainmentfailure.Complete(ornearlycomplete)meltingoftheicesupply,incombinationwithfailureofsprayrecirculation,eventuallyresultsinfailureoftheCookNuclearHantcontainmentduetooverpressurization.Thetimerequiredtofailthecontainmentbyoverpressurizationdependsuponthesteamingrate,whichinturndependsontheamountofwaterinjectedintothecontainmentduringtheaccidentsequenceprogressionandonthedistributionofcoredebrisfollowingcorerelocation.Thefailuremechanismassociatedwithcontainmentoverpressureisduetoexceedingtheultimatestrengthofcertainkeystructuralcomponentsorattachments.Thislimitismostlikelytobeapproachedgradually,sothattheenergydeliveredisonlysufficienttoinducearelativelysmallrupturearea.Theseverityofthesourcetermdependsstronglyonthecontainmentfailuretiming.Failureintheimmediatetimeperiodofvesselfailureisdearlythemostserious,astheoverallairbornefissionproductmassproducedduringasevereaccidentisnevergreaterthanitisinthesmallspanoftimedirectlyaftervesselfailure.Whenevercontainmentpressurizationlagsconsiderablybehindvesselfailure,substantialfissionproduct4-38 retentionthroughnaturallyoccurringdepositionmechanisms(e.g.,sedimentation,impaction,etc.)isfacilitated.~,ContainmentfailureattheCookNuclearPlantismostlikelytooccuratthebasemat/cylinderjunction.Thefloorintheannularcompartmentisexpectedtobefloodedatthetimeofcontainmentfailure,duetomeltingoftheiceand/orsprayinjection.Waterwouldalsooccupythelowercompartmentfloor.Thesetwocompartments(annularandlower)areseparatedbythecranewallbutareabletocommunicatethroughpipesleevesandotheropenings.Thelevelofcommunicationbetweentheannularandlowercompartmentsandthesizeofthebreakincontainmentdeterminesthesubsequentcontainmentresponseandaccidentprogression.Opencommunicationbetweentheannularandlowercompartmentswouldleadtoexpulsionofallwaterintheannularandlowercompartmentsuponfailureatthebasemat.Thisleavesonlywaterinthecavity,whichwillnotbereplenishedbyrecirculationonceithasboiledoKExpulsionofwaterpoolsfromcontainmentsweepsoutsomeportionofthefissionproductswhichhadsettledintothem.Thecontainmentpressuremostlikelycontinuestogoupduringthiswaterdischarge,butitmaynotincreaseenoughtofailthecontainmentelsewhere(i.e.,inthecontainmentgasspace)beforeallthewateronthefloorhadbeenejected.Oncethewaterhasallbeendischarged,containmentdepressurizationwouldbeginasthecontainmentatmosphereventsthroughthebreakatthebasematjunction.4.7DSourceTermAnalysisThepurposeofthesourcetermanalysiswastoquantitativelydescribethemagnitudeandcompositionoffissionproductreleasetotheenvironmentresultingfromtheseverecoredamageaccidentsdefinedinthelevel1study.ToadequatelyaddressthecomplexitiesassociatedwithfissionproducttransportandreleaseandtoaccountforthespeciTiclevel1sequencedefinitionsincludingoperatoractions,theDonaldC.Cooksourcetermanalysisreliedontheintegratedsevereaccidentanalysiscode,MAAP.Thiscodecouplestheplantthermalhydraulicresponseandfissionproductbehaviortoproperlymodelfeedbackbetweenthetwo.Furthermore,MAAPcananalyzeallphasesofsevereaccidentprogressionaccountingfortheimpactoftheprimarysystem,containment,engineeredsafetyfeatures,andoperatoractions.Inregardtofissionproducttransport,MAAPbeginstrackingthefissionproductsastheyexistinthenormallyintactfuelmatrix.Thisinitialfissionproductinventorywasorganizedbychemicalpropertiesinto12groupswithinMAAP.Theinitialinventoryofeachofthe12fissionproductgroupsspecifictoCookNuclearPlantasderivedfromtheMAAPparameterfileareasfollows(Reference61):e,FissionPrducruInitialInventol1)NobleGases(Xe,Kr)2)CsI(volatile)3)TeO>4)SrO5)MoO>6)CsOH(volatile)7)BaO8)LazOs(&PrzOg+NdgOs,SmgOs+YgOg)9)CeO>10)Sb11)Tez(volatile)12)UOz(&NpO>+PuO>)10478102128236462991566661384196280ThefissionproductsarespecifictoCookNuclearHantandbasedonORIGENcalculations(Reference62).Thistotalinventoryoffissionproductsisgenerallycharacterizedasnoblegases,volatile4-39

~~fissionproducts(groups2,6,11)andnon-volatilefissionproducts(groups3,4,5,7,S,9,10,12).Thesourcetermanalysissummarizedinthissectionreportsthemassfractionreleasedforeachofthesethreecategories.4.72.1MAAPAnalysesNineteensequences(15fromthetop40CETendstatesofTable4.6-1,threesequencesaddressingfailuretoisolate,andoneothersequenceofinterest)wereselectedforsourcetermanalysesusingMAAP3.0BRevision17.02.Thissectiondescribesthesesequences.SeveralassumptionsmadefortheMAAPcalculationsareoutlinedheresincetheysignificantlyaffectthecalculatedsourcetermresults.(1)Thelevel2analysisassumeda48hourmissiontime,whilethelevel1analysisusedamissiontimeof24hours.Hence,accidentprogressionwasstudiedforaperiodoftimebeyondwhichAccidentManagementactivitieswouldbeimplementedtoalterthecourseoftheaccident.(2)Acranewallseparatesthelowercompartmentfromtheannularcompartment.Itisassumedthatholesinthecranewallatvariouselevationswouldallowanequalizedwaterlevelinbothcompartmentatanytime.ForfurtherdetailsseeSection4.1.1.1.(3)Airbornefissionproductreleasetotheenvironmentwasassumedtooccurthroughasmallbreakofabout0.17ftzlocatedatthebottomoftheannularcompartmentnearthebasemat-cylinderjunctionduetoshearfailureofthebasematconcrete.Thisfailurewasassumedtooccurduetooverpressureat36psig(Reference53).Atthetimeofcontainmentfailure,thereiswateraccumulatedinthelowerandannularcompartments,regardlessofwhetherthereisinjectionoftheRWST.Thiswateristheresultoficemelting.However,iftheRWSTisinjected,morewaterwouldbeinthecontainment.Thepresenceofwaterinthelowercontainmentnotonlypreventsimmediateairbornereleasefromthebreak,butalsoallowscontainmentpressurizationtocontinueuntilallwaterisdischargedfromthecontainment.AssumingaBernoullifIow,pushinga2xl0lb,11fttallwaterpooloutofthecontainmentthrougha5"holeunderpressureof50psiawouldtakeabout1hour,withoutconsideringsoilresistance.Thisonehourorlessofwaterdrainingtimeisaccountedforinthecalculations,dependingontheamountofwaterpresentineachsequence.ForsequenceswithRWSTinjection,onehourisassumed.ForsequenceswithoutRWSTinjection,35minutesisassumed.Hence,inthecalculations,totallossofcontainmentwaterfromtheannularandlowercompartmentsismodeledaccordingtotheabovetimedelayfollowingthebasematfailure.(4)Forthepurposesofcomputingthecontainmentresponseandlongtermsourcetermresponse,fissionproductsdepositedintheannularandlowercompartmentswereassumedtobesweptoutofthecontainmentbywater.Itisuncertain,however,howmuchofthefissionproductinventorywouldbetransportedwiththewater.Hence,allfusionproductsdepositedintheannularandlowercompartmentspriortocontainmentfailureshouldbeconsideredasavailableforaqueousrelease,andnotameasureoftheactualwaterrelease.Thehandlingofaqueousfissionproductreleaseisaddressedinthelevel3analysis.AccidentprogressionparametersforallanalyzedsequencesaresummarizedinTable4,7-1Thistablecontainsinformationsuchasaccidenttimingandconditions,hydrogenburnsandsourceterm.Table4.7-2summarizesenvironmentalreleaseintermsof"airbornerelease"and"availableforaqueousrelease."BasedontheMAAPsourcetermresults,areleasecategorywasassignedandafrequencyofeachreleasecategorywascalculatedforeachoftheindicatedsequences.TheseresultsareshowninTable4.7-3.Eachanalyzedsequenceisdescribedbelow.

eA-SequenceDescription:Thisaccidentscenarioisinitiatedbya4.0sq.ft.(27inchequivalentdiameter)largebreakLOCAatthebottomofahorizontalrunofthecoldleg.Thefollowingeventtreenodesforthissequence(Reference47)weremodeledforthesourcetermanalysisbasedona48houraccidenttimeframe:(1)ACC-3of3accumulatorsinjecttothecoldlegs(2)LPI-1of2RHRpumpsirjectto1of3intactcoldlegs(3)CSI-1of2trainsofcontainmentsprayinjectionoperational(4)CSR-1of2containmentspraytrainsswitchedfromtheRWSTtotherecirculationsump(5)HI-1of2trainsofhydrogenignitersinbothupperandlowercompartmentsoperational.Thissequenceassumedanoperationalfailuretoestablishlowpressurerecirculation(LPR).AutomaticallyactuatedRHRinjectionandcontainmentsprayinjectionpumpswereassumedoperationaluntilthewaterlevelintheRWSTreachedthe32%lowlevelsetpoint.Fromthispoint,theRHRirjectionwasterminatedandthecontainmentsprayrecirculationwasassumedtooperatethroughtheentireaccidenttimeframeof48hours.SequenceQuantification:0,Thisaccidentscenarioresultedinarapidblowdownofprimarysysteminventoryintothelowercompartment.ContainmentsprayinjectionwasactivatedimmediatelyfollowingRCSblowdown.Withinahalfaminuteafterthebreakinitiation,theblowdownwascompleteandtheprimarysystempressuredroppedbelow400psia.Twentyfourminutesintotheaccident,theRHRinjectionwasterminatedandcontainmentspraywasswitchedtorecirculationmodewhentheRWSTlowlevelsetpointwasreached.Withoutcontinuedirjectionintotheprimarysystem,duetofailuretoestablishlowpressurerecirculation,thecoreuncoveredat37minutes.Thiswasfollowedbycorerelocationtothelowerheadat1.5hoursandfailureofthevesseloneminutelater.Thecavitywasdrywhencoredebriswasdischargedontothecavityfloor,andremaineddryforthewholeaccidenttimeframe.Waterinthelowercompartmentreacheditshighestlevel(10.6ft)aftericedepletionat27hrs.Thiswaterlevelwaslowerthanthecavitycurbheight(11.2ft).Hence,wateraccumulatedonthelowercompartmentfloorbutneverspilledintothecavity.TheseMAAPresultsassumedthatonly68%oftheRWSTinventorywasinjectedintothecontainmentduetotheunsuccessfulswitchtorecirculationmodeat32%lowlevelsetpoint.Substantialconcretefloorerosionduetocore-concreteattackbegan30minutesaftervesselfailure.Attheendofthe48hrtimeframe,concreteerosiondepthtotaled6ft,whichyieldedanaverageerosiondepthrateof0.13ft/hr.Non-condensiblegasesgeneratedfromthecor~oncreteattackcausedcontainmentpressuretoincreaseattherateof0.4psi/hr.Thecontainmentpressurereached30.5psiat48hrs.Toreachthecontainmentultimatepressureatthisrate,itwouldtake100hrs(4days).Thisaccidentsequenceresultedin28.7%oxidationofinshoreZircaloycladding.About504lbsofhydrogenburnedinthelowercompartment,intheicecondenserupperplenumandintheuppercompartment.

Intermittentautoignitionburns,duetohighgastemperature,occurredinsidethecavityfor10.5hrstotaling513lbsofhydrogen.Themaximumpressureandtemperatureintheuppercompartmentwere37.2psiaand1369'F,respectively.Thesemaximumconditionsoccurredforaveryshorttimeduringtheburnintheuppercompartmentat3.7hrs.Thereleaseoffissionproductstotheenvironmentwasassumedtooccurthroughnormalleakage(2x10ft)fromtheannularcompartmentsincethecontainmentdidnotfailduringthisaccidentscenario.UsingCsIanindicatorforvolatilefissionproductsandCeO>asanindicatorforthenon-volatilefissionproducts,environmentalreleaseforthisaccidentscenarioiscalculatedtobe:AirborneReleaseNoblegases(%)Vo]atilefissionproduct(Csi)(%)Non-volatilefissionproduct(CeOz)(%)0.191.4x10s1.6xl0+eLA-SequenceDescription:~~~~~~~~~~~~~~~~~~~~Thisaccidentscenarioisalsoinitiatedbya4,0sq.ft.(27inchequivalentdiameter)largebreakLOCAatthebottomofahorizontalrunofthecoldleg.Thefollowingeventtreenodesforthissequenceweremodeledforthesourcetermanalysisbasedona48hourmissiontime:(1)ACC-3of3accumulatorsinjecttothecoldlegs(2)LPI-1of2RHRpumpsto1of3intactcoldlegs(3)CSI-1of2trainsofcontainmentsprayinjection(4)HI-1of2trainsofhydrogenignitersinbothupperandlowercompartmentwereoperational.Thissequenceassumedanoperationalfailuretoestablishlowpressurerecirculation(LPR)andcontainmentsprayrecirculation(CSR).AutomaticallyactuatedRHRinjectionandcontainmentsprayinjectionpumpswereassumedoperationaluntilthewaterintheRWSTwasdepleted.SequenceQuantification:ThisaccidentscenarioresultsinaveryrapidblowdownofprimarysysteminventoryintothelowercompartmentandrapiddepressurizationoftheprimarysystemsimilartosequenceLLO-5.Withinhalfaminuteafterthebreakinitiation,theprimarysystempressuredroppedbelow400psia.Approximately40minutesintotheaccident,theRHRinjectionwasterminatedduetothedepletionoftheRWSTinventory.Withoutcontinuedinjectionintotheprimarysystemduetothefailureoflowpressurerecirculation,thecorewasuncoveredabout20minuteslater.Thiswasfollowedbycorerelocationintothelowerheadat1.9hours andthefailureofthevesseloneminutelater.Thetimingofvesselfailurewasdelayedby23minutescomparedtosequenceLLO-5.Thiswas'becausethissequenceallowedtheECCSpumpstocompletelydraintheRWST.Therewasnowaterinthecavitywhencoredebriswasdischargedontothecavityfioor.However,waterinthelowercompartmentreachedthecavitycurbheight(11.2ft)andspilledintothecavityalmostimmediatelyaftervesselfailure.ThisspilloverofwaterintothecavitywasaresultofinjectingallRWSTinventoryintothecontainment.Steamingfromwithinthecavityeventuallycausedthedepletionoficeat4.7hrs.Followingtheicedepletion,thecontainmentpressureincreasedfrom19psiaattherateof12psi/hr.Thecontainmentfailedonoverpressureat7.4hours.Cavitydryoutoccurredat21hrsintotheaccident.Concretefloorerosionduetocor~oncreteattackbeganabout2hoursafterthecavitydriedout.Attheendofthe48hrtimeframe,concreteerosiondepthtotaledto3.4ft,whichyieldedanaverageerosionrateof0.14ft/hrandthetemperatureofcoredebriswas3000'F.About1000lbsofhydrogenwasproducedbyconcreteerosion.Thisaccidentsequenceresultedinin-vesselgenerationof660lbsofhydrogendueto28,9%oxidationofin-coreZircaloycladding.About392lbsofhydrogenwereburnedinthelowercompartmentandintheicecondenserupperplenum.Themaximumtemperatureintheuppercompartmentpriortocontainmentfailurewas212'F.Aftercontainmentbasematjunctionfailure,thecontainmentpressurecontinuedtoincreaseuntilwaterintheannularandlowercompartmentswascompletelydischargedoutthroughthe5.6"diameterbreak(0.17ft)inthebasematjunction.Itwasassumedthatonehourwouldberequiredtoforcethewateroutofcontainment.Thecontainmentreached64psiabeforegraduallydepressurizingthroughthebreakinthebasematjunction.UsingCsIasanindicatorforvolatilefissionproductsandCeOzasanindicatorfornon-volatilefissionproducts,environmentalreleaseforthisaccidentscenarioiscalculatedtobe:AvailableforAirbornereleaseaqueousrelease0)Noblegases(%)Volatilefissionproduct(CsI)(%)Non-volatilefissionproduct(CeOz)(%)1007.70.1228.03.3x10seA-8'O-8'equenceDescription:ThisaccidentscenarioisthepreviouslargeLOCAsequence(LL0-8),withafailuretoisolateintheannularcompartment.Anareaequivalenttoa10"diameterpipewasassumedtobeopentotheoutsideofthecontainment.SequenceQuantification:Thissequenceassumedcontainmentfailureatthebeginningofanaccidentasaresultoffailuretoisolatethecontainment.TheunisolatedpipeprecludedanysubstantialcontainmentpressurizationaftericedepletionaswasseeninsequenceLLO-8.Maximumpressureattainedduringthesequencewaslessthan18psia.0)

Hence,containmentpressureandtemperaturewerequitedifferentfromLLO-8.However,accidenttimingwasverysimilartosequenceLLO-8includingtimeofcoreuncovery,timeofcorerelocation,timeofvesselfailure,timeoficedepletion,andsteamingrateaswellascavityspilloveranddryouttime.Similarbasematerosionwasalsoobserved.Steamingfromthecavityduringaperiodof17hrsbetweenicedepletionandcavitydryoutresultedincontainmentpressure2to3psiabovetheambientlevel.Thisslightlyhighpressure,comparedtoambientpressureforsequenceLLO-S,helpedsuppressrevaporizationoffissionproducts.TheresultingsourcetermwassimilartosequenceLLOYD.AirbornereleaseNoblegases(%)Volatilefissionproduct(%)Non-volatilefissionproduct(%)10011.50.22MediumLA-SequenceDescription:Thisaccidentscenarioisinitiatedbya0.049sq.ft.(3inchequivalentdiameter)mediumbreakLOCAatthebottomofahorizontalrunofthecoldleg.Thefollowingeventtreenodesforthissequence(Reference47)weremodeledforthesourcetermanalysisbasedona4Shouraccidenttimeframe:(1)ACC-3of3accumulatorsirjecttothecoldlegs(2)HP2-'neSIpumpandonechargingpumpinjecttointactcoldlegs(3)OA6-RCScooldownusing450gpmofAFWtoSGsand2outof4SGPORVsopenforsteamdump(4)CSI-1of2trainsofcontainmentsprayinjectionoperational(5)HI-1of2trainsofhydrogenignitersinbothupperandlowercontainmentisoperational.Thissequenceassumedanoperationalfailuretoestablishhighpressurerecirculation(HPR)andcontainmentsprayrecirculation(CSR).AllECCSpumpswereassumedoperationaluntildepletionoftheRWST.Auxiliaryfeedwaterwasassumedavailablefromthetimeofaccidentinitiation.AtwohourdelaywasassumedbeforeoperatorsinitiatedRCScooldown.SequenceQuantification:Thisaccidentscenarioresultedinablowdownofprimarysysteminventoryintothecontainmentlowercompartment.Aboutonehourafterthebreakinitiation,theprimarysystempressurehaddroppedtonearly600psia.HighpressureinjectionwasterminatedduetodepletionoftheRWST,1.2hrsintotheaccident.Withoutcontinuedirjectionintotheprimarysystemduetothefailureofhighpressurerecirculation,thecorestartedtouncoverat1.5hrs.Thiswasfollowedbycorerelocationtothelowerheadat5.2hoursandthefailureofthevessel.

Therewere9ftofwaterinthecavitywhencoredebriswasdischargedontothecavityfioor.Waterinthelowercompartmentreachedthecavitycurbheight(11.2ft)andspilledintothecavityabout2hourspriortovesselfailure.ThespilloverofwaterintothecavitywasaresultofinjectingallRWSTinventoryintothecontainment.Steamingfromwithinthecavityeventuallycausedthedepletionoficeat6.3hrs.Followingicedepletion,thecontainmentpressureincreasedfrom19psiaattherateof10.7psi/hr.Thecontainmentbasematfailedonoverpressureat9.3hours.0)Cavitydryoutoccurredat24hrsintotheaccident.Concretefloorerosionduetocor~ncreteattackbegan3hoursafterthecavitydriedout.After48hrs,theconcreteerosiondepthtotaled2.8ftwhichcorrespondedanaverageerosionrateof0.14ft/hr,andthetemperatureofcoredebriswas3000'F.About850Ibsofhydrogenwereproducedduringcore-concreteinteraction.Thisaccidentsequenceresultedingenerationof840lbsofhydrogendueto35.9%oxidationofin~reZircaloycladding.About499lbsofhydrogenproducedduringtheaccidentwereburnedinthelowercompartment,uppercompartment,andupperplenumoftheicecondenser.Themaximumtemperatureintheuppercompartment(804'F)occurredduringahydrogenburn,immediatelyaftervesselfailure.Followingthecontainmentbasematfailure,waterinthelowercontainmentwasassumedtobecompletelydischargedthroughthe5.6"(0.17ft)breakwithinanhour.Duringthistime,thecontainmentpressurecontinuedtorise(to62psia)beforegradualdepressurizationofthecontainmentbegan.UsingCsIasanindicaterforvolatilefissionproductsandCeO>asanindicatorforthenon-volatilefissionproducts,environmentalreleaseforthisaccidentscenarioiscalculatedtobe:Noblegases(%)Volatilefissionproduct(Csi)(%)Non-volatilefissionproduct(CeO>)(%)Airbornerelease1002,40.10Availableforaqueousreleasecontainmentfailur14.00.00)MediumA-35SequenceDescription:Thisaccidentscenarioisinitiatedbya0.049sq.ft.(3inchequivalentdiameter)mediumbreakLOCAatthebottomofahorizontalrunofthecoldleg.Thefollowingeventtreenodesforthissequence(Reference47)weremodeledforthesourcetermanalysisbasedona48houraccidenttimeframe:(1)ACC-3of3accumulatorsinjecttothecoldlegs(2)CSI-1of2trainsofcontainmentsprayinjectionoperational(3)HI-1of2trainsofhydrogenignitersinbothupperandlowercontainmentisoperational.Thissequenceassumedanoperationalfailuretosuccessfullyestablishcontainmentsprayrecirculation(CSR).AutomaticactuationofthecontainmentsprayinjectionwasassumeduntilwaterintheRWSTwasdepleted.

SequenceQuantification:Thisaccidentsceuuioresultedinablowdownofprimarysysteminventoryintothelowercompartmentanddepressurizationoftheprimarysystem.About40minutesafterthebreakinitiation,theprimarysystempressuredroppedtonearly600psia.ContainmentsprayirjectionwasactuatedandthenwasterminatedduetothedepletionoftheRWSI',1.3hoursintotheaccident.Thecoreuncoveredat29minutes.Thiswasfollowedbycorerelocationtothelowerheadat2.44hoursandfailureofthevesselaminutelater.Theprimarysystempressurepriortovesselfailurewasabout250psia.Therewasnowaterinthecavitywhenallcoredebriswasdischargedontothecavityfloor.Waterinthelowercompartmentreachedthecavitycurbheight(11.2ft.)andspilledintothecavityabout4.5hoursaftervesselfailure.ThespillofwaterintothecavitywasaresultofinjectingallRWSTinventoryintothecontainment.Steamingfromwithinthecavityeventuallycausedthedepletionoficeat8.65hrs.Followingtheicedepletion,thecontainmentpressureincreasedfrom20psiaattherateof12.5psi/hr.Thecontainmentfailedonoverpressureat11.1hours.Cavitydryoutoccurred35hrsintotheaccident.Concretefloorerosionduetocor~oncreteattackbeganshortlyaftervesselfailure.Theerosionwastemporarilyterminatedfor27hrsduetowaterspilloverfromthelowercompartmentuntilthecavitydriedout.After48hrtheconcreteerosiondepthtotaled2,5ft,whichyieldedanaverageerosionrateof0.12ft./hr,andthetemperatureofcoredebriswas3000'F.About580lbsofhydrogenwereproducedpriortocontainmentfailurebyconcreteerosion,ofwhich447lbsburnedinthecavity.Thisaccidentsequenceresultedinin-vesselgenerationof950Ibsofhydrogendueto35.3%oxidationofin-coreZircaloycladding.About403lbsofhydrogenwereburnedinthelowercompartment,theicecondenserupperplenum,andtheuppercompartment.Themaximumtemperatureintheuppercompartment(665'Poccurredduringaburnintheuppercompartmentabout1.5hrsbeforevesselfailure.Aftercontainmentbasematjunctionfailure,thecontainmentpressurecontinuedtoriseuntilwaterintheannularandlowercompartmentswascompletelydischargedthroughthe5.6"diameterbreak(0.17ft)inthebasematjunction.Itwasassumedthatonehourwouldberequiredtopushwateroutofthecontainment.Thecontainmentpressurizedto64psiabeforegraduallydepressurizingthroughthebreakinthebasematjunction.UsingCsIasanindicatorforvolatilefissionproductsandCeO>asanindicatorfornon-volatilefissionproducts,theenvironmentalreleaseforthisaccidentscenarioiscalculatedtobe:AirbornereleaseAvailableforaqueousreleasecontainmentfailuNoblegases(%)VolatilefissionproductNon-volatilefissionproduct(CeOz)(%)2.44.1xl0+23.016.0 MediumA-SequenceDescription:iThisaccidentscenarioisinitiatedbya0.049sq.ft.(3inchequivalentdiameter)mediumbreakLOCAatthebottomofahorizontalrunofthecoldleg.Onlyoneeventtreenodeforthissequence(Reference47)wasmodeledforthesourcetermanalysisbasedona48houraccidenttimeframe:(1)ACC-3of3accumulatorsirjecttothecoldlegsSequenceQuantification:Thisaccidentscenarioresultedinablowdownofprimarysysteminventoryintothelowercompartment.Thecoreuncoveredat28minutesintotheaccident.Thiswasfollowedbycorerelocationtothelowerheadat2.44hrsandthefailureofthereactorvesseloneminutelater.Priortovesselfailure,theprimarysystemwasatapproximately260psia.Duetolowprimarysystempressureatvesselfailure,transportofcoredebristothelowercompartmentdidnotoccur.Allcoredebrisremainedinthecavity.Thecavitywasdrywhencoredebriswasdischargedontothecavityfloor,andremaineddryforthewholeaccidenttimeframe.Waterinthelowercompartmentreacheditshighestlevel(7ft)aftericedepletionat14.4hrs.Thiswaterlevelwaslowerthanthecavitycurbheight(11.2ft).Hence,wateraccumulatedonthelowercompartmentfloorbutneverspilledintothecavity.Substantialconcretefloorerosionduetocor~oncreteattackbeganabout30minutesaftervesselfailure.Attheendofthe48hrtimeframe,concreteerosiondepthtotaled5.2ft,whichyieldedanaverageerosionrateof0.12ft/hr.About750Ibsofhydrogenwereproducedbyconcreteerosion;all750lbsburnedinthecavity.Non-condensiblegasesgeneratedfromthecore-concreteattackcausedcontainmentpressuretoriseattherateof1.3psi/hr.Thecontainmentfailedonoverpressureat37.9hrs.0;Thisaccidentsequenceresultedinin-vesselgenerationof890lbsofhydrogendueto38.6%ofin~reZircaloycladoxidation.About504Ibsofhydrogenwereburnedinthelowercompartment,andtheicecondenserupperplenum.Themaximumtemperatureintheuppercompartment(480'5)occurredatthetimeofcontainmentfailureasaresultofgradualheatingofcontainmentgasbydebrisinthedrycavity.Aftercontainmentbasematjunctionfailure,thecontainmentpressurecontinuedtoriseuntilwaterintheannularandlowercompartmentswascompletelydischargedthroughthe4"diameterbreak(0.09fthm)inthebasematjunction.(Notethatthecomputeranalysisforthissequenceuseda4"vicea5.6"equivalentdiameterfailuresizeasdiscussedinSection4.3.1.Thisdifferencewasduetoatypographicalerrorinthecomputerinput.Sincetheholesizeassumedwouldhaveonlyaminoreffectontheoverallresults,nonewanalysiswasperformed.)Itwasassumedthatonehourwouldberequiredtopushwateroutofthecontainment.Thecontainmentpressurized53psiabeforegraduallydepressurizingthroughthebreakinthebasematjunction.UsingCsIasanindicatorforvolatilefissionproductsandCeO>asanindicatorfornon-volatilefissionproducts,theenvironmentalreleaseforthissequencewascalculatedtobe:

AirbornereleaseAvailableforaqueousreleasecontainmentfailureNoblegases(%)VolatilefissionproductNon-volatilefissionproduct(CeO>)(%)767.78.0x10+34.020.0ILA-22SequenceDescription:Thisaccidentscenarioisinitiatedbya3.14sq.inch(2inchequivalentdiameter)smallbreakLOCAat'thebottomofahorizontalrunofthecoldleg.Thefollowingeventtreenodesforthissequence(Reference47)weremodeledforsourcetermanalysisbasedona48hoursaccidenttimeframe:(1)HP2-(2)OA6-1SIpumpand1chargingpumpinjecttointactcoldlegsRCScooldownusing450gpmofAFWtoSGsand2outof4SGPORVsopenforsteamdump(3)CSI-(4)CSR-1of2trainsofcontainmentsprayinjectionoperational1of2containmentspraystrainsswitchedsuctionfromtheRWSTtotherecirculationsump(5)HI-1of2trainsofhydrogenignitersinbothupperandlowercontainmentisoperational.Thissequenceassumedanoperationalfailuretosuccessfullyestablishhighpressurerecirculation(HPR).AutomaticallyactuatedECCSpumpswereassumedoperationaluntilthewaterlevelintheRWSTreachedthe32%lowlevelsetpoint.Fromthispointon,onlycontainmentsprayrecirculationwasassumedtooperatethroughtheentire48hours.Auxiliaryfeedwaterwasassumedavailablefromthetimeofaccidentinitiation.A2hourdelaytimewasassumedbeforeoperatorsperformedthesteamdumpforRCScooldown.SequenceQuantification:Thisaccidentscenarioresultedinablowdownofprimarysysteminventoryintothelowercompartmentanddepressurizationoftheprimarysystem.AllHP2irjectionwasterminatedwhentheRWSTlowlevelsetpointwasreached,approximately1hourintotheaccident.Withoutcontinuedinjectionintotheprimarysystemduetothefailureofhighpressurerecirculation,thecoreuncoveredat1.94hours.Within3hoursafterthebreakinitiation,theprimarysystempressuredroppedtoabout200psia.Thiswasfollowedbycorerelocationtothelowerheadat7.77hoursandthefailureofthevesseloneminutelater.Thecavitywasdrywhencoredebriswasdischargedontothecavityfloorandremaineddryforthewholeaccidenttimeframe.Waterinthelowercompartmentsreacheditshighestlevel(10.6ft)attheendofthe48hrtimeframe.Atthistime,icedepletionwasnearlycomplete.Thiswaterlevelwaslowerthanthecavitycurbheight(11.2ft).Hence,wateraccumulatedonthelowercompartmentfloorbutneverspilledintothe cavity.ThisMAAPresultassumedthatonly68%ofRWSTinventorywasinjectedintothecontainmentduetoswitchingtorecirculationmodeatthe32%lowRWSTlevelsetpoint.Substantialconcretefloorerosionduetocor~oncreteattackbegan30minutesaftervesselfailure.Attheendofthe48hourtimeframe,concreteerosiondepthtotaled5.2ft,whichyieldedanaverageerosionrateof0.13ft/hr.Non~ndensiblegasesgeneratedfromthecore-concreteattackcausedcontainmentpressuretoincreaseattherateof0.17psi/hr.Thecontainmentpressurereached26psiaat48hrs.Toreachthecontainmentultimatepressureatthisrate,itwouldtake8days.Thisaccidentsequenceresultedingenerationof720Ibsofhydrogengasdueto31.5%oxidationofin~reZircaloycladdingbysteamand980lbsofhydrogengasduetocore-concreteattack.About498lbsofhydrogenproducedduringtheaccidentwereburnedinthelowercompartment,theicecondenserupperplenum,andtheuppercompartment.Intermittentauto-ignitionburnsof544lbsofhydrogen,duetohighgastemperature,occurred'insidethecavityfor12hrsfollowingvesselfailure.Themaximumpressureandtemperatureintheuppercompartmentwere28.6psiaand500'F,respectively.Thesemaximumconditionsoccurredforaveryshorttimeandwereduetoahydrogenburnintheuppercompartmentshortlyaftervesselfailure.Thereleaseoffissionproductstotheenvironmentwasassumedtooccurthroughnormalleakage(2x10ft)fromtheannularcompartmentsincethecontainmentdoesnotfailduringthisaccidentscenario.UsingCsIasanindicatorforvolatilefissionproductsandCeO>asanindicatorfornon-volatilefissionproducts,theenvironmentalreleaseforthisaccidentscenarioiscalculatedtobe:AirbornereleaseNoblegases(%)Volatilefissionproduct(Csi)(%)Non-volatilefissionproduct(CeOz)(%)0.166.9x10+1.2xl0+~!llLOCA-2'L2'equenceDescription:ThisaccidentscenarioisthesameassequenceSLO-2butwithafailuretoisolatethecontainmentintheannularcompartment.Hence,inadditiontothesuccessfuleventtreenodeswhicharemodeledinsequenceSLO-2,anareaequivalenttoa10"diameterpipeopentooutsidethecontainmentwasassumed.SequenceQuantification:ThetimingofmajorcoreandcontainmenteventswereverysimilartosequenceSLO-2,exceptthattimingfortheeventsinthissequencewasdelayed1hour.Thiswasduetoadelayintheautomaticactuationofthecontainmentsprayinjectionasaresultofisolationfailure.ThisdelayinsprayactuationhelpedconservetheRWSTinventoryforvesselinjectionuse.FissionproductreleasetotheenvironmentincreasedseveralordersofmagnitudefromsequenceSLO-2.Theyarecalculatedtobe:0, AirbornereleaseNoblegases(%)Volatilefissionproducts(CsI)(%)Non-volatilefissionproducts(CeO>)(%)90.54.lx10i2.9x10sSmallA-SequenceDescription:Thisaccidentscenarioisinitiatedbya3.14sq.inch(2inchequivalentdiameter)smallbreakLOCAatthebottomofahorizontalrunofthecoldleg.Thefollowingeventtreenodesofthissequence(Reference47)weremodeledforsourcethetermanalysisbasedona48houraccidenttimeframe:(1)HP2-1SIpumpand1chargingpumpinjecttointactcoldlegs(2)OA6-RCScooldownusing450gpmofAFWtoSGsand2outof4SGPORVsopenforsteamdump(3)CSI-1of2trainsofcontainmentsprayinjectionoperational(4)HI-1of2trainsofhydrogenignitersinbothupperandlowercontainmentisoperational.Thissequenceassumedanoperationalfailuretoestablishhighpressurerecirculation(HPR)andcontainmentsprayrecirculation.AutomaticoperationofhighpressureinjectionandcontainmentsprayinjectionpumpswasassumeduntilthedepletionoftheRWST.Auxiliaryfeedwaterwasassumedavailablefromthetimeofaccidentinitiation.AtwohourdelaywasassumedbeforeoperatorsperformedthesteamdumpforRCScooldown.SequenceQuantification:Thisaccidentscenarioresultedinablowdownofprimarysysteminventoryintothelowercompartmentanddepressurizationoftheprimarysystem.Fortwohoursafterthebreakinitiation,primarysystempressureremainedintheneighborhoodof1000psia.AllinjectionwasterminatedduetodepletionoftheRWST,1.3hoursintotheaccident.Withoutcontinuedinjectionintotheprimarysystemduetothefailureofhighpressurerecirculation,thecoreuncoveredat5.6hours.Thiswasfollowedbycorerelocationtothelowerheadat7.7hoursandthefailureofthevesseloneminutelater.Therewasnowaterinthecavitywhencoredebriswasdischargedontothecavityfloor.Waterinthelowercompartmentreachedthecavitycurbheight(11.2ft)andspilledintothecavityabout15secondsaftervesselfailure.Steamingfromwithinthecavityeventuallycausedthedepletionoficeat10hrs.Followingtheicedepletion,thecontainmentpressureincreasedfrom18.5psiaattherateof9.2psi/hr.Thecontainmentfailedonoverpressureat13.5hours.Cavitydryoutoccurredat30hrsintotheaccident.Concretefloorerosionduetocore-concreteattackbegan~~~~~3hoursafterthecavitydriedout.After48hrs,theconcreteerosiondepthtotaled2,1ftwhichyieldedan4-50 averageerosionrateof0.14ft/hr,andthetemperatureofcoredebriswas3000'F.About820Ibsofhydrogenwereproducedbyconcreteerosion.Thisaccidentsequenceresultsinin-vesselgenerationof760lbsofhydrogendueto33.2%oxidationofin~reZircaloycladding.About365lbsofhydrogenproducedduringtheaccidentwereburnedinthelowercompartment,theicecondenserupperplenumandintheuppercompartment.Themaximum630'Ftemperatureintheuppercompartmentoccurredduringhydrogenburninthiscompartmentabout50minutespriortovesselfailure.Aftercontainmentfailure,thecontainmentpressurecontinuedtoriseuntilwaterintheannularandlowercompartmentswascompletelydischargedthroughthe5.6"break(0.17ft)inthebasematjunction.Itwasassumedthatonehourwouldberequiredtopushwateroutofthecontainment.Thecontainmentpressurizedto61psiabeforedepressurizinggraduallythroughthebreak.UsingCsIasanindicatorforvolatiletalionproductsandCeO>asanindicatorfornon-volatilefissionproducts,theenvironmentalreleaseforthisaccidentscenarioiscalculatedtobe:AirbornereleaseAvailableforaqueousreleasecontainmentfailuNoblegases(%)VolatilefissionproductNon-volatilefissionproduct(Ce02)(%)1001.59.5x10s9.00.00'1LA-353SequenceDescription:Thisaccidentscenarioisinitiatedbya3.14sq.inch(2inchequivalentdiameter)smallbreakLOCAatthebottomofahorizontalrunofthecoldleg.Onlytwoeventtreenodesforthissequence(Reference47)weremodeledforthesourcetermanalysisbasedona48houraccidenttimeframe:(1)CSI-1of2trainsofcontainmentsprayinjectionoperational(2)HI-1of2trainsofhydrogenignitersinbothupperandlowercontainmentoperational.AutomaticoperationofcontainmentsprayinjectionwasassumeduntilthedepletionoftheRWST.SequenceQuantification:Thisaccidentscenarioresultsinrelativelyhighprimarysystempressureuntilvesselfailure.ContainmentsprayirjectionwasactuatedandthenwasterminatedduetothedepletionoftheRWST,1.5hoursintotheaccident.Duetothefailureofhighpressureinjection,thecoreuncoveredatabout1hr.Thiswasfollowedbycorerelocationtothelowerheadat2.63hoursandthefailureofthevesseloneminutelater.Atthetimeofvesselfailure,theprimarysystempressurewasabout400psia.Highpressuremeltejectioncaused80%ofthecoredebristobetransportedtothelowercompartment.4-51 Therewasnowaterinthecavitywhencoredebriswasdischargedontothecavityfioor.However,waterinthelowercompartmentreachedthecavitycurbheight(11.2ft)andspilledintothecavityalmostimmediatelyaftervesselfailure,preventingcavityfioor.cor~oncreteattack.Steaming(mostlyfromthelowercompartment)eventuallycausedthedepletionoficeat10.6hrs.Followingtheicedepletion,thecontainmentpressureincreasedfrom18psiaattherateof6.0psi/hr.Thecontainmentfailedonoverpressureat15.9hours.Dryoutinthecavityandlowercompartmentdidnotoccurduringtheaccidenttimeframe.Thus,noconcreteerosionoccurredexceptforasmallinitialerosionoflowercompartmentfloorconcreteof(0.008ftdepth)followinghighpressuremeltejection.Theerosionwasimmediatelyterminatedduetothepresenceofalargeamountofwaterinthelowercompartment.Thisaccidentsequenceresultsinin-vesselgenerationof740Ibsofhydrogendueto32.5%oxidationofin~reZircaloycladding.About387lbsofhydrogenproducedduringtheaccidentwereburnedinthelowercompartment,theicecondenserupperplenum,andtheuppercompartment.Themaximum580'Ftemperatureintheuppercompartmentoccurredforaveryshorttimeduringhydrogenburnintheuppercompartmentslightly,priortovesselfailure.Aftercontainmentfailure,thecontainmentpressurecontinuedtoriseuntilwaterintheannularandlowercompartmentswascompletelydischargedthroughthe5.6"diameterbreak(0.17fthm)inthebasematjunction.Itwasassumedthatonehourwouldberequiredtopushwateroutofthecontainment.Thecontainmentpressurizedto62psiabeforedepressurizinggraduallythroughthebreak.UsingCsIasanindicatorforvolatilefissionproductsandCeO>asanindicatorfornon-volatilefissionproducts,theenvironmentalreleaseforthisaccidentscenariowascalculatedtobe:AirbornereleaseAvailableforaqueousreleasecontainmentfailurNoblegases(%)Volatilefissionproduct(CsI)(%)Non-volatilefissionproduct(CeOQ(%)1005.41.8xl0424.02.8teamtorTubeRture-3SGR-3SequenceDescription:Thisaccidentscenarioisinitiatedbyasteamgeneratortuberuptureinvolvingadoubleendedruptureofasingletube(0.943sq.inbreakarea).Thefollowingeventtreenodesforthissequence(Reference47)weremodeledforthesourcetermanalysisbasedona48houraccidentframe:(1)AF2-1of3auxiliaryfeedwaterpumpstointactsteamgenerators(atotal200,000Ib/hraux.feedflowwasassumedbasedonminimumtotalAFWflowspecifiedintheEOPE-0(Reference4).(2)HPI-(3)SGI-1chargingpumpirjectingto1of4coldlegsclosureofMSIVonfaultedsteamgenerator4-52 (4)SSV-allsecondaryreliefvalvesonfaultedS/Gnotstuckopen(5)CSI-1of2trainsofcontainmentsprayoperational(6)CSR-1of2containmentspraytrainsswitchedsuctionfromRWSTtorecirculationsump(7)HI-1of2trainsofhydrogenignitersinbothupperandlowercontainmentisoperational.ThissequenceassumedfailuretoestablishRCScooldownanddepressurization.AchargingpumpwasassumedoperationaluntilthewaterlevelintheRWSTreachedthe32%lowlevelsetpoint.Afterthispoint,containmentspraywouldbeinrecirculationmode.SequenceQuantification:Thisaccidentscenarioresultedinapressuredecreaseintheprimarysystemtothelevelofthesteamgeneratorsafetyvalvesetpoint.Theprimarysystemdischargedcoolanttothesecondarysideofthefaultedsteamgeneratorthroughthetuberuptureareauntilequilibriumwasattained.Within20minutesaftertheaccidentinitiation,theprimarysystempressuredroppedtoabout1300psiaandremainedatthisleveluntilhighpressureinjectionusingonechargingpumpwasterminated(7.8hrs)intotheaccidentduetotheRWSTlowlevel.Followingchargingpumptermination,boththeRCSandthefaultedsteamgeneratorstabilizedat1080psiauntilvesselfailure,whichoccurredat29.7hrs.Uptothetimeofvesselfailure,containmentconditionsremainedessentiallyundisturbedsincetherewasnodirectdischargeofprimarysystemfluidintothecontainment.Theicemassremainedunchanged.Containmentspray(inrecirculationmode)wasactuatedonlyatvesselfailure.Highpressuremeltejectionduringvesselfailuretransportedabout70%ofcoredebristothelowercompartment;therestwasleftinthecavity.Thisaccidentsequenceresultedin940Ibsofhydrogengenerationdueto40%oxidationofinshoreZircaloycladdingand42lbsofhydrogenduetominimalcor~oncreteattack.About107Ibsofhydrogenburnedinthelowercompartment,theuppercompartment,andtheicecondenserupperplenum,and51lbsburnedinthecavity.AfractionofinshorehydrogenescapedtotheenvironmentthroughtheS/Gsafetyvalves.Themaximumpressureandtemperatureintheuppercompartmentwere22,2psiaand170'F,respectively.Thesemaximumconditionsoccurredasaspikeduetohydrogenburnintheuppercompartmentshortlyaftervesselfailure.UsingCsIasanindicatorforvolatilefissionproductsandCeO>asanindicatorfornon-volatilefissionproducts,theenvironmentalreleaseforthissequenceiscalculatedtobe:AirbornereleaseNoblegas(%)Volatilefissionproducts(Csi)(%)Non-volatilefissionproducts(CeOz)(%)13.50.43.7xlO~O~4-53 SteamGeneratoc'ubeRSequenceDescription:Thisaccidentscenarioisinitiatedbyasteamgeneratortuberuptureinvolvingadoubleendedruptureofasingletube(0.943sq.in.breakarea).Thefollowingeventtreenodesforthissequenceweremodeledforthesourcetermanalysisbasedona48hraccidenttimeframe:(1)AF2-1of3auxiliaryfeedwaterpumpstointactsteamgenerators(total200,000lb/hraux.feedflowwasassumed)(2)HPI-1chargingpumpinjectingto1of4coldlegs(3)SGI-closureofMSIVonfaultedsteamgenerator(4)SSV(failure)-secondaryreliefvalvesonfaultedS/Gstuckopen(5)CSI-1of2trainsofcontainmentsprayoperational(6)CSR-1of2containmentspraytrainsswitchedsuctionfromRWSTtorecirculationsump(7)HI-1of2trainsofhydrogenignitersinbothupperandlowercontainmentisoperational.ThissequenceassumedlossofthefaultedsteamgeneratorintegritywhentheS/GPORVstuckopenat30minutesintotheaccident.ThesuccessfulnodesofthissequencearesimilartosequenceSGR-3exceptthatthefaultedsteamgeneratorwasoverfilledleadingtothestuckwpenSIGPORV.Therefore,thecontainmentbypasstotheenvironmentwasestablishedthroughthetuberuptureandthestuckwpenS/GPORV.AchargingpumpwasassumedoperationaluntilthewaterlevelintheRWSTreachedthe32%lowlevelsetpoint.Containmentspray,ifactuated,wouldbeinrecirculationmodeafterthispoint.SequenceQuantification:Thisaccidentscenarioresultedinaprimarysystempressuredecreasetothelevelofthesteamgeneratorsafetyvalvesetpoint.FurtherdepressurizationoccurredwhentheSIGPORVstuckopen.Theprimarysystempressuredroppedto-550psiapriortoterminationofhighpressureinjectionat6.7hrsintotheaccident.Aftertheterminationofhighpressureinjection,theprimarysystempressuredroppedquicklyto330psia.Coreuncoverystartedat13.8hrs.Thiswasfollowedbycorerelocationtothelowerheadat15.7hrsandfailureofthereactorvesseloneminutelater.Atthetimeofvesselfailure,theRCSpressurewasabout370psia.Alldischargedcorematerialremainedinthecavity.Blowdownfollowingvesselfailurecausedicemeltingandcontainmentsprayactuationinrecirculationmode.Waterfromicemeltingwasavailableforsprayrecirculation.Thecavitywasdrywhencoredebriswasdischargedontothecavityfloor,andremaineddryforthewholeaccidentsequence.Waterinthelowercompartmentsreacheditshighestlevel(2.8ft)aftericedepletionat48hrs.Atthistimetherewasmorethanamillionpoundsoficeleftunmelted.Thiswaterlevelwaslowerthanthecavitycurbheight(11.2ft).Hence,wateraccumulatedonthelowercompartmentfloorbutneverspilledintothecavity.Substantialconcretefioorerosionduetocore-concreteattackbegan2hoursaftervesselfailure.Attheendofthe48hrtimeframe,concreteerosiondepthtotaled4ft,whichyieldedanaverageerosiondepthrateof4-54 0.13ft/hr.Non~ndensiblegasesgeneratedfromthecor~oncreteattackcausedcontainmentpressuretoincreaseattherateof0.1psi/hr.Thecontainmentpressurereached19.5psiat48hrs.Themaximumpressureandtemperatureintheuppercompartmentwere20,4psiand154'F,respectively.Theseconditionsoccurredduringtheprimarysystemblowdownfollowingvesselfailure.O.rThisaccidentresultedin980Ibsofhydrogengenerationdueto37.4%oxidationofinshoreZircaloycladdingand850lbsofhydrogenduetocore-concreteattackinthecavity.About612lbsofhydrogenburnedinthecavity,and95Ibsburnedoutsidethecavity.AfractionofinshorehydrogenescapedthroughthestuckopenS/GPORV.ThereleaseoffissionproductstotheenvironmentmostlyoccurredthroughthestuckopenS/GPORV.UsingCsIasanindicatorforvolatilefissionproductsandCe02asanindicatorfornon-volatilefissionproducts,releasetotheenvironmentforthissequencewascalculatedtobe:AirbornereleaseNoblegases(%)Volatilefissionproducts(Csl)(%)Non-volatilefissionproducts(CeO>)(%)90.025.08.2x103SteamGeneratorTubeRture-Thisaccidentscenarioisinitiatedbyasteamgeneratortuberuptureinvolvingonesteamgenerator.Adoubleendedruptureofasingletube(0.943sq.in.breakarea)wasassumedforthisanalysis.Thissequenceonlymodelsoneeventtreenode,i.e.,AF2-asupplyofauxiliaryfeedwatertotheintactSGs(Reference47).Atotal200,000lb/hrofauxiliaryfeedwaterflowdistributedequallytothe3intactSGswasassumed.TheMSIVonthefaultedsteamgeneratorwasnotdosed,duetothefailuretoisolatethefaultedsteamgenerator.Thisresultedincontainmentbypasstotheenvironment.Thebypasspathwouldbefromtheprimarysystemtothesecondarysystemandeventuallytotheenvironment.0)SequenceQuantification:Thisaccidentscenarioresultedinapressuredecreaseintheprimarysystemthroughtheleakatthetuberupture,duetothepressuredifferencebetweentheprimarysystemandthesecondarysideofthefaultedsteamgenerator.Within20minutesaftertheaccidentinitiation,theprimarysystempressurehasdecreasedtoabout1100psia,anditremainedatthislevelfor3hrs.Pressureinthesecondarysideofintactsteamgeneratorsincreasedrapidlyfrom692psia(ataccidentinitiationtime)toabout1080-1090psiaandremainedinthisrangeuntilvesselfailure.PressureirithefaultedSGdecreasedtoalevelbelow200psiaandstabilizedatthislevelforaboutanhourbeforedroppingfurther.Thecoreuncoveredat2.9hrs.Thiswasfollowedbycorerelocationtothelowerheadat4.3hrs.andfailureofthereactorvesseloneminutelater.Primarysystempressurewas530psiapriortovesselfailure,andhighpressuremeltejectionresultedinthetransportof95%ofcorematerialsdischargedfromtheRPVtothelowercompartment.Icedepletionoccurredat14hrs.About4.5hrslaterthecontainmentfailedonoverpressure.Thisaccidentsequenceresultedin35.6%oxidationofZircaloycladding.Nohydrogenburnwasobservedduringthe4-55 sequencesincemostin-vesselhydrogenleakedouttotheenvironmentpriortovesselfailure.Noseverecore-concreteattackoccurredduringthe48hrstimeframe.Themaximumtemperatureof260'Fintheuppercompartmentpriortocontainmentfailureoccurredduringtheblowdownfollowingvesselfailure.Aftercontainmentbasematjunctionfailure,thecontainmentpressurecontinuedtoriseuntilwaterintheannularandlowercompartmentswascompletelydischargedthroughthe5.6"diameterbreak(0.17ft)inthebasematjunction.Itwasassumedthat35minuteswouldberequiredtopushwateroutofthecontainment.Thecontainmentpressurizedto56psiabeforegraduallydepressurizingthroughthebreakinthebasematjunction.UsingCsIasanindicatorforvolatilefissionproductsandCeOzasanindicatorfornon-volatilefissionproducts,releasetotheenvironmentforthissequencewascalculatedtobe:AirbornereleaseAvailableforaqueousreleaseninmntfailurNoblegases(%)Volatilefissionproducts(Csl)(%)Non-volatilefissionproducts(CeOz)(%)10047.39.6x10s-19.06,2x10~~~~~InterfaciS.LOCA-ThisaccidentscenarioisinitiatedbyaRHRcooldownsuctionLOCAduetothefailureoftwomotoroperatedvalveswhicharethepressureinterfacebetweentheprimarysystemandtheRHRpumpsuctionpiping.Inthissequence,primarysystemfluidatfullreactorpressureispostulatedtopassintoalowpressuresegmentoftheRHRsystemwhereitcausestheRHRpumpsealstofail.AnevaluationoftheRHRpumpsealsidentifiedanupperboundleakageareaof0.1fthmifbothpumpsealsfail(Reference47).ThisupperboundbreakareaisintherangeofamediumLOCA.HencearapiddepressurizationoftheRCSduetothelossofinventoryfromthebreakwouldbeexpectedforthisaccidentscenario.Thisbreakareaalsoconstitutesarelativelylargeareathroughwhichfissionproductsaretransportedoutofthecontainmentandintotheauxiliarybuilding.Thisquantificationassumedtheupperboundleakageareaof0.1ft.InadditiontothelossofRCSinventorytotheauxiliarybuilding,RCSdepressurizationisacceleratedbythefluidlossthroughRHRsystemreliefvalves.ThesethreereliefvalvesareconnectedtotheRHRpipingtoprovideoverpressureprotectionandrelieve,to'thecontainment,900gpmeachat450psig.Twoeventtreenodesforthissequence(Reference47)weremodeledforthesourcetermanalysisbasedona48houraccidenttimeframe:(1)BRH-RHRpipingdoesnotfailbutpumpsealleakageinbothoftheRHRtrainsresults(2)HP2-1of2chargingpumpsand1of2SIpumpsinjectto1intactcoldlegSinceemergencycorecoolingrecirculationislostforthistype'ofaccident,highpressureECCSirjection(HP2)areassumedtooperateuntilthedepletionoftheRWSTinventory.OperatoractionstoisolatetheRHRsealLOCAisassumedunsuccessfuland,sincethissequencefailstoisolatethebreak,nomitigationactionsforRCScooldownanddepressurizationareconsideredfurther.4-56 SequenceQuantification:Thisaccidentsceueioresultedinarapidblowdownofprimarysysteminventorydirectlyintotheauxiliarybuildingwithoutpassingthroughthecontainmentvolume.TherewasaslightcontainmentpressureincreaseduetoasmalldiscluegeofsteamintothecontainmentthroughtheRHRreliefvalves.However,substantialpressurizationofthecontainmentdidnotoccuruntilvesselfailure.WithinanhouraftertheRWSTinventorydepletion,whichoccurredat4.9hours,thecoreuncoverybegan.Vesselfailureoccurredat6.7hrsfromthetimeofaccidentinitiation.3Thecavitywasdrywhencoredebriswasdischargedontothecavityfloor,andremaineddryforthewholeaccidenttimeframe.Waterinthelowercompartmentreacheditshighestlevel(5.3ft)aftericedepletionat45hrs.Thiswaterlevelwaslowerthanthecavitycurbheight(11.2ft).Hence,wateraccumulatedonthelowercompartmentfloorbutneverspilledintothecavity.Substantialconcretefloorerosionduetocore-concreteattackbeganabout1houraftervesselfailure.Attheendofthe48hrtimeframe,concreteerosiondepthtotaled5.3ft,whichyieldedanaverageerosionrateof0.13ft/hr.Containmentpressurereacheditsmaximumvalueof18,8psiaduringtheRCSblowdownfollowingvesselfailure.Thisaccidentresultedin830lbshydrogengenerationdueto36.2%oxidationofin-coreZircaloycladdingand970lbshydrogenduetocore-concreteattackinthecavity.About658lbsofhydrogenburnedinthecavity,and73Ibsburnedoutsidethecavity.Afractionofinshorehydrogenescapedtotheauxiliarybuilding.Thereleaseoffissionproductsfromtheprimarysystemintotheauxiliarybuildingduringthesequenceiscalculatedtobe:Noblegases(%)Volatilefissionproducts(Csl)(%)Non-volatilefissionproducts(CeOz)(%)Airbornerelease99.9930.25~'largepartofthefissionproductreleasefromtheprimarysystemwouldplateoutintheauxiliarybuilding.IftheresultsofanEPRIevaluationofcontainmentbypassthroughatypicalauxiliarybuilding(Ref.EPRINP4586-LVolume1)isusedasabasis,thedecontaminationfactorsexpectedforvolatileandnon-volatilefissionproductsarebetween7.5and20andbetween11.4and67.5,respectively.Baseduponthesebounds,theestimatedenvironmentalreleaseis:AirbornereleaseNoblegases(%)Volatilefissionproducts(Csi)(%)Non-volatilefissionproducts(CeO>)(%)99.94.7-12.53,8x10s-2.3xl0z4-57

~~~StationBlackout-500-50ThisaccidentscenarioisinitiatedbyalossofoffsiteACpoweraccompaniedbythelossoftheonsiteemergencyACpowerdistributionsystem;therefore,criticalsafetyandsupportsystemswhichrelyonACpowerwerenotavailable.SinceRCPsealsupportsystemswereunavailable,leakageofRCSfluidthroughtheRCPsealsoccurred.Sealleakageflowratewasdeterminedbaseduponthesuccessorfailureofthefirstthreeeventtreenodes,i.e.,(1)turbine-drivenAFW,(2)reactorcooldown,and(3)continuationofAFW.Thisdeterminedthetimelimitbywhichpowermustberestoredtopreventcoreuncoveryasdiscussedintheeventtreenotebook(Reference47).TheRCPsealleakageflowratewasthendeterminedfromaWestinghousecurverepresentingtherelationshipbetweencoreuncoverytimeandRCPsealleakage(Reference39).Theleakagefiowrateforthissequencewas96gpmperpump.Thefollowingeventtreenodesforthissequence(Reference47)weremodeledforthesourcetermanalysisbasedona48houraccidenttimeframe.(1)AFZ-Turbine-drivenpumpdeliversflowtosteamgeneratorsfor4hrs.(2)RCD-RCScooleddownby2of4steamgeneratorPORVs.Onehourdelaywasassumedforthisaction.(3)AFC-Turbine-drivenpumpcontinuestodeliverflowtosteamgeneratorsforadditional2hourspastAFI'hourmissiontime.SequenceQuantification:Thisaccidentscenarioresultedinhighprimarysystempressureuntilvesselfailure.Withtheavailabilityofturbine-drivenauxiliaryfeedwaterfor6hoursandthesuccessofRCScooldown,theprimarysystempressuredroppedto300-400psiforabout8hours,causingthesealleakageflowtobemostlyliquid.Asaresult,thecontainmentpressureincreasedslowlyto44psiawithoutsubstantiallymeltingtheice.Coreuncoverywasdelayeduntil12.23hrsintotheaccident.Thiswasfollowedbycorerelocationtothelowerheadat14.03hrs,andthefailureofthereactorvesselaminutelater.Priortovesselfailure,theprimarysystemwasatapproximately1700psia.Highpressuremeltejectionduringvesselfailurecausedabout87%ofthecoredebristobetransportedtothelowercompartment.Theremainderaccumulatedinthereactorcavity.Substantialicemeltingdidnotoccuruntilvesselfailure.Thisaccidentsequenceresultsinin-vesselgenerationof960Ibsofhydrogendueto42.1%oxidationofinshoreZircaloycladding.Noconcreteerosionoccurred.Thetemperatureofcoredebrisat48hrswas1900'Finthelowercompartmentand1100'Finthecavity.Waterinthelowercompartmentreacheditshighestlevel(7.0ft)aftericedepletionat24.6hrs.Thiswaterlevelwaslowerthanthecavitycurbheight(11.2ft).Hence,wateraccumulatedonthelowercompartmentfloorbutneverspilledintothecavity.However,becauseonly13%ofcoredebriswasinthecavity,waterexpelledfromthevesselduringvesselfailurekeptthecavitywetfor7hours.Steamingfromboththelowercompartmentandfromthecavityeventuallycausedthedepletionoficeat24.6hrs.Followingtheicedepletion,thecontainmentpressureincreasedfrom21psiaattherateof8.8psi/hr.Thecontainmentfailedonoverpressureat27.9hours.Aftercontainmentbasematjunctionfailure,thecontainmentpressurecontinuedtoriseuntilwaterintheannularandlowercompartmentswascompletelydischargedthroughthe5.6"diameterbreak(0.17ft)inthebasematjunction.Itwasassumedthat35minuteswouldberequiredtopushwateroutofthecontainment.Thecontainmentpressurizedto56psiabeforegraduallydepressurizingthroughthebreakinthebasematjunction.4-58 UsingCsIasanupperboundindicatorforvolatilefissionproductsandCeO>asanindicatorfornon-volatilefissionproducts,theenvironmentalreleaseforthissequencewascalculatedtobeAirbornereleaseAvailableforaqueousreleasecontainmentfailurNoblegases(%)Volatilefissionproducts(Csl)(%)Non-volatilefissionproducts(CeO>)(%)82.01.63.3x10~30.01.6x10stationBlackout-I1ThisaccidentscenarioisinitiatedbyalossofoffsiteACpoweraccompaniedbythelossoftheonsiteemergencyACpowerdistributionsystem;therefore,criticalsafetyandsupportsystemswhichreliedonACpowerwerenotavailable.SinceRCPsealsupportsystemswereunavailable,leakageofRCSfluidthroughtheRCPsealsoccurred.TheRCPsealleakageflowratedependeduponthesuccessorfailureofthefirstthreeeventtreenodes,whichdeterminedthetimelimitbywhichpowermustberestoredtopreventcoreuncovery,asdiscussedintheeventtreenotebook(Reference47).TheRCPsealleakageflowwasthendeterminedfromaWestinghousecurverepresentingtherelationbetweencoreuncoverytimeandRCPsealleakagefWestinghouse,1986].Sincethissequencehasnosuccessfulnodes,theleakageflowforthissequencewasdeterminedtobeequivalenttothemaximumrateexpectedforthesealleakage(Reference47).Thiswas480gpmperpump.)SequenceQuantification:Thisaccidentscenarioresultedinhighprimarysystempressureuntilvesselfailure.Withouttheavailabilityofturbine-drivenauxiliaryfeedwater,thecoreuncoveredat1.7hrsintotheaccident.Thiswasfollowedbycorerelocationtothelowerheadat3.3hrsandthefailureofthereactorvesselaminutelater.Priortovesselfailure,theprimarysystempressurewasabout450psia.Highpressuremeltejectionduringvesselfailurecausedabout10%ofcoredebristobetransportedtothelowercompartment.Therestwasleftinthecavity.Waterinthelowercompartmentreacheditshighestlevel(7.0ft)aftericedepletionat14hrs.Thiswaterlevelwaslowerthanthecavitycurbheight(11.2ft).Hence,wateraccumulatedonthelowercompartmentfloorbutneverspilledintothecavity.Steamingfromthelowercompartmenteventuallycausedthedepletionoficeat14hrs.Followingtheicedepletion,thecontainmentpressureincreasedfrom20psiaattherateof2.76psi/hr.Thecontainmentfailedonoverpressureat25.2hours.'Concretefloorerosionduetocore-concreteattackbegan1.5hoursaftervesselfailure.Attheendof48hrtimeframe,concreteerosiondepthtotaled5.2ftwhichyieldedanaverageerosionrateof0.12ft/hr.Thetemperatureofcoredebrisinthecavitywas2800'F.About960lbsofhydrogenwereproducedbyconcreteerosion,ofwhich532lbsburnedinthecavity.Thisaccidentsequenceresultedinin-vesselgenerationof760lbsofhydrogendueto33.4%oxidationofin-coreZircaloycladding.About251Ibsofhydrogenwereburnedinthelowercompartment,theicecondenserupperplenum,andtheuppercompartment.i4-59 Themaximumtemperatureintheuppercompartment(520'Poccurredduringaburnintheuppercompartmentabout2hrsaftervesselfailure.Aftercontainmentbasematjunctionfailure,thecontainment.pressurecontinuedtoriseuntilwaterintheannularandlowercompartmentswascompletelydischargedthroughthe5.6"diameterbreak(0.17ft~)inthebasematjunction.Itwasassumedthat35minuteswouldberequiredtopushwateroutofthecontainment.Thecontainmentreached53psiabeforegraduallydepressurizingthroughthebreakinthebasematjunction.UsingCsIasanindicatorforvolatilefissionproductsandCeO>asanindicatorfornon-volatilefissionproducts,theenvironmentalreleaseforthissequencewascalculatedtobe:AirbornereleaseAvailableforaqueousreleasecontainmentfailurNoblegases(%)Volatilefissionproducts(Csl)(%)Non-volatilefissionproducts(CeO~)(%)890.41x10~48.07.5StationBlackout-1'BO-190'equenceDescription:ThisaccidentscenarioconsistedoftheadditionofcontainmentisolationfailuretosequenceSBO-190.A~~~~~~~~~~~~failureareaequivalenttoa10"diameterpipe,opentooutsidethecontainmentfromtheannularcompartment,wasassumed.HSequenceQuantification:Thissequenceassumedcontainmentfailurefromthebeginningofanaccidentasaresultoffailuretoisolatethecontainment.Theunisolatedpipeprecludedanysubstantialcontainmentpressurizationfollowingicedepletion,aswasseeninsequenceSBO-190.Hence,containmentpressureandtemperaturewerequitedifferentfromSBO-190.However,accidenttimingswereverysimilartosequenceSBO-190includingthetimeofcoreuncovery,thetimeofcorerelocation,andthetimeofvesselfailure.Icedepletionoccurred3.5hrsearlierthanforthebasecase.Nohydrogenburnwasobserved.UsingCsIandCe02asindicatorsforreleaseofvolatileandnon-volatilefissionproducts,respectively,theenvironmentalreleaseforthisaccidentscenariowascalculatedtobe:AirbornereleaseAvailableforaqueousreleasecontainmentfailureNoblegases(%)Volatilefissionproducts(Csl)(%)Non-volatilefissionproducts(CeOQ(%)1005.325.65x10'-60 StationBlackout-ISequenceDescription:1810-1815AsdescribedinsequenceSBO-50,RCPsealleakagewasdeterminedbaseduponthesuccessorfailureofthefirstthreeeventtreenodes.Thisstationblackoutsequencewasnotsuccessfulinanyofthreventtreenodes,resultinginmaximumsealleakageof480gpmperpump.Thefollowingeventtreenodes(Reference47)weremodeledforthesourcetermanalysisbasedona48houraccidenttimeframe:(1)XH5-powerrestoredwithin1hourwithadditional1/2hourforequipmentrecovery(2)CSI-1of2trainsofcontainmentsprayinjectionafter1.5hour(4)HI-(3)CSR-1of2containmentspraytrainsswitchedsuctionfromtheRWSTtotherecirculationsump1of2trainsofhydrogenignitersinbothupperandlowercontainmentisoperationalafter1.5hoursSequenceQuantification:Thisaccidentscenarioresultedinhigh(1100-1200psia)primarysystempressureuntilcoreuncoveryat1.73hrsintotheaccident.Thiswasfollowedbycorerelocationtothelowerheadat3.33hrsandthefailureofthereactorvesselaminutelater.Priortovesselfailure,theprimarysystempressurewasslightlyabove400psia.Highpressuremeltejectionduringvesselfailurecausedabout38%ofcoredebristobetransportedtothelowercompartment.Therestwasleftinthecavity.Thecavitywasdrywhencoredebriswasdischargedontothecavityfioor,anditremaineddryforthewholeaccidenttimeframe.Waterinthelowercompartmentreacheditshighestlevel.(10.3ft)attheendof48hrtimeframe.Atthistime,therewasstill200,000Ibsoficeintheicecondenser.Thiswaterlevelwaslowerthanthecavitycurbheight(11.2ft).Hence,wateraccumulatedonthelowercompartmentfioorbutneverspilledintothecavity.ThisMAAPanalysisassumedthatonly68%ofRWSTinventorywasinjectedintothecontainment,duetotheswitchtorecirculationmodeatthe32%lowlevelsetpoint.0)Substantialconcretefloorerosionduetocor~oncreteattackbeganabout2hoursaftervesselfailure.Attheendofthe48hrtimeframe,concreteerosiondepthtotaled3.7ft,whichyieldedanaverageerosionrateof0.09ft/hr.Nonwondensiblegasesgeneratedfromthecore-concreteattackcausedcontainmentpressuretoincreaseattherateof0.1psi/hr.Thecontainmentpressurereached20.4psiat48hrs.Toreachthecontainmentultimatepressureatthisrate,itwouldtake14.6days.Thisaccidentsequenceresultedingenerationof745Ibshydrogendueto32.5%oxidationofinshoreZircaloydaddingand660lbs.hydrogenduetocor~oncreteattack.About489Ibsofhydrogenproducedduringtheaccidentwereburnedinthelowercompartment,theicecondenserupperplenum,theuppercompartment,andtheannularcompartment.Intermittentautoignitionburnsof513lbshydrogen,duetohighgastemperatureoccurredinsidethecavityfor6hrs.Nootherburnswereobservedafter12hrsintoanaccident.Themaximumpressureandtemperatureintheuppercompartmentwere25psiaand524'F,respectively.Thesemaximumconditionsoccurredforaveryshorttimeduringahydrogenburnintheuppercompartmentjustpriortovesselfailure.Thereleaseoffissionproductstotheenvironmentwasassumedtooccurthroughnormalleakage(2x10ft)fromtheannularcompartmentsincethecontainmentdidnotfailduringthisaccidentscenario.UsingCsI asanindicatorforvolatilefissionproductsandCeO>asanindicatorfornon-volatilefissionproducts,the~~~environmentalreleaseforthisaccidentscenariowascalculatedtobe:AirbornereleaseAvailableforaqueousreleasecontainmentfailureNoblegases(%)Volatilefissionproducts(Csl)(%)Non-volatilefissionproducts(CeO~)(%)0,151.1x10s3.4x107~ofsitePower-21-21SequenceDescription:ThisaccidentscenarioisinitiatedbyalossofoffsiteACpowertothenormaldistributionlinesservingthestationandisfollowedbyimmediaterestorationofanalternateoremergencyACpowersourcetoatleastonesafetybus.Thissequencedoesnotmodelanyeventtreenodes(Reference47).SequenceQuantification:kThisaccidentscenarioresultedinhigh(-2300psia)primarysystempressureuntilvesselfailureat4hoursintotheaccident.Highpressuremeltejectionduringvesselfailurecausedabout60%ofcoredebristobetransportedtothelowercompartment.Therestwasleftinthecavity.Waterinthelowercompartmentreacheditsmaximumlevel(7ft)atthetimeoficedepletion.Thiswaterlevelwaslowerthanthecavitycurbheight(11.2ft).Hence,wateraccumulatedonthelowercompartmentfloorbutneverspilledintothecavity.Steamingfromthelowercompartmenteventuallycausedthedepletionoficeat9.7hrs.Followingtheicedepletion,thecontainmentpressureincreasedfrom18psiaattherateof6.9psi/hr.Thecontainmentfailedonoverpressureat14.3hours.Nosubstantialcore-concreteattackwasobservedfortheentire48hrtimeframeduetotheproportionaldistributionofcoredebrisinthecavityandinthelowercompartment,whichresultedintemperatureof2500'Ffordebrisinthecavityandof1600'Ffordebrisinthelowercompartment.Thissequenceresultedinin-vesselgenerationof880lbsofhydrogendueto38.3%oxidationofinshoreZircaloycladding.About310Ibsofhydrogenwereburnedinthelowercompartment,theicecondenserupperplenum,andtheuppercompartment.Themaximumtemperatureof750'Fintheuppercompartmentoccurredduringburnintheuppercompartmentaboutonehouraftervesselfailure.Aftercontainmentbasematjunctionfailure,thecontainmentpressurecontinuedtoriseuntilwaterintheannularandlowercompartmentswascompletelydischargedthroughthe5.6"diameterbreak(0.17ft)inthebasematjunction.Itwasassumedthat35minuteswouldberequiredtopushwateroutofthecontainment.Thecontainmentpressurizedto56psiabeforegraduallydepressurizingthroughthebreakinthebasematjunction.UsingCsIasanindicatorforvolatilefissionproductsandCeO>asanindicatorfornon-volatilefissionproducts,theenvironmentalreleaseforthissequencewascalculatedtobe:

AvailableforAirbornereleaseaqueousrelease0>Noblegases(%)Volatilefissionproducts(Csl)(%)Non-volatilefissionproducts(CeO>)(%)6.25.0x10~29.02.6xl0+4.72SensitivityAnalysisReference20identifiedin-vesselandex-vesselphenomenawhichmighthavesignificanteffectsoncontainmentfailuretimingandtheassociatedsourcetermrelease.ThesephenomenaarelistedinTable4.74.ThepurposeofthissectionistosummarizehowthesephenomenologicaluncertaintieswereaddressedintheCookNuclearPlantIPE.InadditiontoaddressingtheuncertaintiesidentifiedinNUREG-1335,sensitivityanalyseswerealsoperformedtodeterminetherangeoffissionproductreleaseduetotheuncertaintiesincontainmentfailuresizeandlocation.4.70.1ApproachInordertoaddresstheuncertaintiesinin-vesselandex-vesselphenomenaoutlinedinReference20atwostepapproachwastaken.ThefirststepwastoaddressthephenomenaindetailedPhenomenologicalEvaluationSummarypapers(References53-59).Thesephenomenologicalevaluationswereconcernedwiththeunlikelihoodorlikelihoodofcontainmentfailuremechanisms,aswellascontainmentfragility.Ifthephenomenawereconservativelyevaluatedasnotcontributingtocontainmentfailure,uncertaintiesassociatedwiththesephenomenaweregivennofurtherconsideration.0:Thesecondstepaddressed,throughthevariationofrelevantMAAPmodelparameters,phenomenologicaluncertaintiesnotaddressedinthePhenomenologicalEvaluationSummaries.TherangesofMAAPmodelparametersforsensitivityanalyseswererecommendedintheEPRIdocumentEPRITR-100167(Reference52).Withthesetwosteps,allphenomenarelevanttotheCookNuclearPlantareaddressed.4.762ScopeTable4.7Qlists(1)phenomenaidentifiedinReference20forsensitivityanalyses,(2)analysesperformedtoaddressthecorrespondingphenomena,and(3)relatedMAAPparametersforsensitivityruns.Table4.7-5liststhesuggestedvaluesofMAAPparametersinconsiderationofuncertaintiesintheparametersthemselvesoruncertaintiesintheuseofthoseparameters.4.7BBMAAPAnalysesThroughthetwostepapproachdescribedintheprevioussection,severaluncertainties,asindicatedinTable4.7Qwouldhavenoimpactoncontainmentfailureand,consequently,noimpactonsourceterm.Therefore,nofurtheranalysesarerequired.Phenomenathatmayhavehadanimpactonsourcetermandwerestudiedassensitivitycasesareasfollows:Hydrogenburncompleteness0,4-63 In-vesselhydrogenproduction/corerelocationHotlegcreeprupturefailureinahighpressuresequenceReduceddebriscoolabilityLargebasematfailuresizeContainmentfailurelocationattheequipmenthatchMAAPanalysesofthesephenomenaaredescribedbelow.HydrogenBurnCompletenessinLLO-5Purpose:ThisanalysisassessestheeffectsoftheflamefluxmultiplieronhydrogenburncompletenessforsequenceLLO-5.ThebasecaseLLO-5showedhightemperature/pressurecausedbyburnintheuppercompartment.Conditions:TheMAAPparameterFLPHI,whichrepresentsburncompletenesswasincreasedfromavalueof2to10toenhanceburncompletenessinturbulentwellmixedatmospherescausedbycontainmentsprays.Results:Severalkeytimingswereidenticaltothebasecase(sequenceLLO-5)includingtimeofcoreuncovery,vesselfailureandbasematerosion.Burncharacteristicsdifferedslightlyfromthebasecase.Themostnotableonewasanearlyoccurrenceofaburnintheuppercompartment.Inthesensitivityrun,aburnintheuppercompartmentoccurred40minutesafterRPVfailure(comparedto2hoursafterRPVfailureforthebasecase).Asaresult,icedepleted20minutesearlierthanthebasecase.Besidestheeffectsonpressureandtemperaturespikeswhichlastedforaveryshorttimeperiod,theoverallcontainmentpressureandtemperaturebehaviorswereapproximatelyidenticaltothebasecase.Therewasnochangeinfissionproductreleasetotheenvironmentfromthebasecase.Therefore,theeffectsofburncompletenessontheoverallcontainmentperformanceandsourcetermwereconcludedasnotimportant.In-vesselHydrogenProductioninLLO-5Purpose:Thissequenceassessestheeffectsofthecoreblockagemodeloncladoxidationand,hence,in-vesselhydrogenproduction.Theuseofthismodelisgenerallyknowntoreducetheinshorehydrogenproduction.ThecoreblockagemodelinMAAPdoesnotallowforoxidationandgasflowthroughcorenodesaftertheonsetofmeltinginthatnode.MAAP'scoreblockagemodelaccountsfortheeffectsofchannelblockagephenomenasuchassurfaceareatovolumereductionaftermelting,geometricdeformation,hydraulicdiameterreductions,andmovementofunreactedZircaloytolowerpartofthecore.Conditions:Thecoreblockagemodelwasnotusedinthesourcetermcalculationsofthebasecases,ThecoreblockagemodelisimplementedbysettingFCRBLKequaltol.

Results:Theoverallaccidenttimingandcontainmentresponsearesimilartothebasecase.Thecladoxidationwasreducedto20.8%comparedto28.7%forthebasecase.Hydrogenproductionwasreducedby185Ibsduetocoreblockage.Noburnoccurredintheuppercompartment.Hence,theanalysesofthebasecaseswereconservativewithrespecttohydrogenproductionduringanaccident.Therewasnoeffectonsourcetermasaresultofimplementingcoreblockagemodel.HotLegCreepRuptureFailurePurpose:Inthebasesequence(LSP-21),anelevatedhotleg/surgelinetemperatureupto1230'FoccurredpriortovesselfailurewhentheRCSpressurewasatanelevatedpressureof2350psia.TheseelevatedRCSconditionsapproachedthelowlandrangeofpotentialcreeprupturefailureofthehotleg.Thissequenceassessestheeffectsonsourcetermshouldcreepruptureofthehotlegoccur.Conditions:Hotlegfailurebasedona7"breaksizewasassumedtooccurjustpriortovesselfailureasthehotlegtemperatureapproacheditsmaximumvalueof1230'F.Results:'ailureofthehotlegpriortoRPVfailureresultedinconvertingahighpressuresequenceintoalowpressuresequenceduetorapidRCSdepressurizationthroughthebreakarea.Hence,thevesselfailedatlowpressure(-200psia).Alldischargedcoredebrisaccumulatedwithinthecavity.Thecavityremaineddryandthedebrisremaineduncooledforthewholeaccidenttimeframecausingmorenon-volatilefusionproductreleasesandsevereconcreteerosion.Therewasnodirectsteamingbydebrisfromthewaterpoolinthelowercompartment.Comparedtothebasecase,icedepletionforthesensitivitycasewasdelayedby2hoursandcontainmentfailurewasdelayedby13hours.Gastemperaturesinsidethevesselaftervesselfailureremainedmuchhigher(1500'F-2000'F)thanthebasecase((1000'F)causingmorevolatilefissionproductstocomeoutoftheprimarysystemanddepositintherelativelycoldannularandlowercompartments(sincealldebriswasinthecavity).Asaresult,fissionproductsavailableforaqueousreleasethroughthebreakinthebasematincreasedtremendouslyfromthebasecasewhilethevolatileairbornereleasereducedfrom6.2%to0.6%.Availablefraueousrelete%BaseCaseNoble9388Volatile0.586.2Non-volatile3.2x105x10'4.68.328.42.6x10+Itisnotedthattheoverallcontainmentresponsesincludingsourcetermweresimilartoananalyzedstationblackoutsequence(SBO-190).ReducedDebrisCoolabilityinSBO-50Purpose:Thissequenceassessestheeffectsofreduceddebriscoolabilityonthesourcetermrelease.Conditions:Thecriticalheatfluxforthedebris,waterinterfaceiscontrolledbyMAAPparameterfilevariableFCHF.Thisvariablewasreducedfrom.1to.02.

Results:Thereduceddebriscoolabilityshowednoeffectonvesselfailuretiminganddebrisdistribution(92%transportedtothelowercompartment).Containmentpressureandtemperaturecharacteristics,icedepletiontimeandcontainmentfailuretimeweresimilartothebasecase.However,fissionproducttransportduringthetimefromvesselfailuretocontainmentfailurewasaffected.5%morevolatilefissionproductswerereleasedtothecontainmentfromtheRPV.Slightlymorefissionproductsdepositedintheannularandlowercompartmentswereobservedinthis,run.Hence,theamountofvolatileandnon-volatilefissionproductsavailableforaqueousreleaseatthetimeofcontainmentfailurewashigherthanthebasecase.Airbornevolatilefissionproductsslightlydecreasedfrom1.6%forthebasecaseto1.5%.Thecomparisonof'sourcetermisshownbelow:Availableforaueousrelease%BaseCaseNoble82Volatile1.5Non-volatile7x10~821.63,3x10~352x10s30.01.6x10sLargeBasematFailureSizePurpose:Toassesstheeffectsofbasematjunctionfailuresizeonsourcetermandtoestablisharangeforairbornefissionproductreleaseduetouncertaintiesinthecontainmentfailuresize.Theaqueousreleaseisafunctionofthedepositedfissionproductsonthelowerandannularcompartmentfloors.Breaksizedoesnotimpactthesedepositsthustheaqueousreleaseisnotimpactedbythissensitivity.Sequences:Allbasesequencesthatresultincontainmentfailureduetooverpressure.Conditions:Thebasematfailuresizeisincreasedfromasmallvalue(0.17fthm)toaverylargevalueof40fthmsuchthatmaximumsourcetermswouldbecalculated.Thecalculatedsourcetermsrepresenttheupperlimitfortheairbornewhilethebasesourcetermsrepresentthelowerlimitofairbornesourcetermrangedefinedbyuncertaintiesinfailuresize.Totalwaterlossfromthecontainmentwasassumedtooccuralmostinstantaneouslyfollowingcontainmentfailure.Results:Accidenteventtimingsandcontainmentresponsecharacteristicswere,identicaluptothecontainmentfailuretime.ThesourcetermsarecomparedwiththebasecasesinTable4.74,Theresultsshowthatinmostcasesaverylargefailuresizeleadstoanincrease,byafactorof2orless,involatileandnon-volatileairbornesourcetermreleasesexceptforthenon-volatilesourcetermreleasesinseq.LSP-21whichincreaseby5ordersofmagnitude(from5xl07%to0.01%).AnotherexceptionisSLO-35wherevolatilefissionproductreleaseinsteadofincreasing,decreasedslightlyfrom5.4%to3.4%,EquipmentHatchFailurePurpose:Failureatthebasematmaybesmallinbreaksizeresultingincontinuedcontainmentpressurizationandafailureattheequipmenthatchpriortotheexpulsionofwaterfromthelowercompartment.

Sequences:Allbasesequencesthatresultincontainmentfailureduetooverpressure.Conditions:ToperformMAAPanalysisofequipmenthatchfailure,thecontainmentultimatepressureof58psigisassumed.Thefailuresizeisassumedthesameasthebasecases.Nocontainmentwaterlossisallowedtooccurthroughthebasematjunctionfailure(whichoccursat36psig)tosimulateasituationthatwatercouldnotbepushedoutofthecontainmentduetouncertaintiesinfailuresizeandlocation,and,possibly,soilresistance,forexample.Consequently,noaqueousreleaseoffissionproductsisautomaticallyassumed.Results:Accidenttimingsandcontainmentresponsecharacteristicswereidenticaltothebasesequencesuptothebasematfailuretime.ForMLO-40,containmentoverpressureoccurredatamuchslowrate(-1.6psi/hr);andtheequipmenthatchfailedabout9hoursafterthebasematfailure.TheairbornesourcetermsarecomparedwiththeairbornesourcetermsofthebasecaseinTable4.74.Substantialreductionbyseveralfactorsinvolatilereleaseandareductionbyafactorof2orlessinnon-volatilereleasewouldresultwithafailureattheequipmenthatch.TheexceptionstothisconclusionareLLO-8andMLO-35whereanincreaseinvolatilereleasewasobserved.Itshouldbenotedthattheairbornesourcetermsforcasesthatendinfailingtheequipmenthatchwithapartiallossofcontainmentwaterwouldliebetweenthevaluescalculatedhereandthebasevalues;andtheaqueousreleasewouldbesmallerthanthebasevalues.4.7.4ConclusionThelevel2analysisdiscussedabovereviewedcontainmentfailuremodesandtheresultingsourcetermrelease.Givencoredamage,thereisan85.4%probabilitycontainmentwillbesuccessful.Thereis,therefore,a14.6%probabilitythatcontainmentwillbesuccessful.TheconditionalprobabilityofcontainmentfailurebyfailuremodeisshowninFigure4.7-1.TherankingofsourcetermreleasecategoriesissummarizedinTable4.7-3.Ofthebypasssequences,SGTRsequencesarethemajorcontributorstotheoverallsourceterm.Emergencyoperatingproceduresinstructtheoperatorstoterminateallfeedwaterflowtothefaultedsteamgenerator.Shouldtheintegrityofthefaultedgeneratornotremainintact,thenfissionproductsreleasedtothesteamgeneratorthroughthetuberupturecanpassdirectlytotheenvironmentwithoutthebenefitofscrubbingbythesecondarysidewater.Maintainingwaterlevelinthesecondarysideofthefaultedsteamgeneratorcouldsubstantiallyreducethesourceterm.FailureoftheCookNuclearPlantcontainmentwillmostprobablybeduetoshearofthebasematconcreteatthecylinderbasematjunction.Becauseofthemanyuncertaintiessurroundingthisfailuremechanism,itwasdiHiculttopredictthecharacteristicsoftheactualbreachofcontainment.TheCookNuclearPlantIPEassumedthatcontainmentoverpressurizationwouldresultina5.6"equivalentdiameterholethroughthebasemattotheatmosphere.Anotherkeyassumptioninthelevel2analysisresultingfromthecontainmentfailurelocation,inthebasematbelowanyexpectedwaterlevelincontainment,wasthatwaterinthelowerandannularcompartmentswouldbelostthroughthebasematfailureandthatthewatermustbelostbeforeanyairbornereleasecouldoccur.Thesizeofthefailurewasfoundthroughsensitivitystudiestohave'nlyasmalleffect(i.e.onlyafactorof2orless)ontheoverallairborneandaqueousfissionproductreleases.Thelocationofthecontainmentfailure,however,coulddramaticallylowertheoverallfissionproductrelease.Shouldcontainmentfailureoccurabovethewaterlevelincontainment,thenaqueousfissionproductreleasewouldbevirtuallyeliminated.Containmentfailurelocationwouldnothavealargeeffectontheoverallairbornerelease.

Theassumptionthatallwaterinthelowerandannularcompartmentswouldbelostfollowingcontainmentfailurehasagreatimpactonthesourcetermanalysis.Thisassumptionwaspredicatedonthephysicalconfigurationofthecontainmentobservedduringwalkdowns.ThelowerandannularcompartmentsoftheCookNuclearHantcontainmentareseparatedbythecranewallwhichhassleevestoallowpipingtopassbetweenthecompartments.Whilethereisonlyasmallamountofclearancebetweenthepipeandthewall,itwasassumedthatthelargenumberofthesepenetrationscanallowwaterlevelinboththelowerandannularcompartmentstoequalize.Whencontainmentfailureoccurs,therefore,waterinventorywillbelostfrombothcompartments.Anothersignificantimpactoftheassumptionthatwaterlevelequalizesintheannularandlowercompartmentsisthatthereactorcavityisdryformostcontainmentfailuresequences.TheinventoryoftheRWSTisnotenoughtofillboththelowerandannularcompartmentstothelevelwherespillovertothereactorcavitywouldoccur.Icemelt,however,combinedwithRWSTinjectionwillcausespilloverfromthelowercompartmenttothereactorcavity.Becauseoftheaccidentsequencetiming,insufficienticehasmeltedpriortovesselfailuretoallowspillovertothereactorcavityformostaccidentsequences.Thedrycavityresultsingreaterfissionproductentrainmentandairborneconcentrations.

Page1of6Table4.7-1CONTAINMENTSTATUSANDLEVELIISOURCETERMSUMMARYOFDOMINANTSEQUENCESSequenceHo.SequenceFrequencySuenceDesignatorCORE/CONTAINNENTRESPONSETimeofCoreUncover(hr)TimeofCoreRelocation(hr)TimeofVesselFailure(hr)TimeofIceDepletion(hr)TimeofContaiwentFailure(hr)HaxisuaUpperCompartmentPressure(psia)NaxisuaUpperCompartmentTrature('F)CavityMaterLevel9VesselFailure(ft)FractionofCladReactedinVessel(X)HydrogenBurnLocationTotalHydrogenBurned(lb)Outside/InsideCavityENVIRONNENTALRELEASEQ48hrNobleRelease(X)VolatileFPRelease(X)Non-VolatileFPRelease(X)2.831x10ALR-S0.621.501.5226.95Hone()37.213690.028.7L,U,IU,C504/5130.21.4x101.6x10LLO1~124x10ALCJ0.911.891.904.727.36>50.72120.028.9L,IU392/010035.70.12Bg(3)1.349x10ALC-U0.901.884.520.017.93450.028.3L,IU,C405/3510011.50.22NOTES:1)CcepartmentslU=upper,L~loxer,A~annular,C=cavity,IU=I/Oupperplena.2)Eventdidnotoccurduring48hrs.timeframe.3)Theprimeindicatescontairmentisolationfailure.4)SeeTable4.7-2forasplitbetxeenairborneandaqueousrelease.

Page2of6Table4.7-1(Continued)CONTAINMENTSTATUSANDLEVELIISOURCETERMQS&IARYOFDOMINANTSEQUENCESSuenceNo.SequenceFrequencySequenceDesignatorCORE/CONTAINMENTRESPONSETimeofCoreUncovery(hr)TimeofCoreRelocation(hr)TimeofVesselFailure(hr)TimeofIceDeletion(hr)TimeofContainnentFailure(hr)KaxinxmUpperCompartmentPressure(ia)MaximmUpperCompartmentTrature('F)CavityMaterLevel9VesselFailure(ft)FractionofCladReactedinVessel(X)HydrogenBurnLocationTotalHydrogenBurned(lb)Outside/InsideCavitENVIRONMENTALRELEASEQ48hrNobleRelease(X)VolatileFPRelease(X)Non-VolatileFPRelease(X)4.457x10SLC-J1.485.245.266.309.26>50.78409.035.9L,U,IU,C499/010016.40.1KLO351.777x10SHCM0.472.442.468.6511.10>50.70.035.3L,U,IU,C403/4479425.416.0401.334x10SHWIF-M0.472.442.4614.3937.91>50.74800.038.6L,IU,C504/7507641.720.0NOTES:1)Compartments:U=upper,L~lower,A"-annular,C=cavity,IU=I/Oupperplenum.2)Eventdidnotoccurduring48hrs.timeframe.3)Theprimeindicatescontairmentisolationfailure.4)SeeTable4.7-2forasplitbetweenairborneandaqueousrelease.4-70 Page3of6Table4.7-1(Continued)CONTAINMENTSTATUSANDLEVELIISOURCETERMSUMMi'ARYOFDOMNANTSEQUENCESSequenceHo.SLO352g(s)SequenceFrequencySequenceDesignatorCORE/COKTAIHMEHTRESPOHSETimeofCoreUncovery(hr)TimeofCoreRelocation(hr)TimeofVesselFailure(hr)TimeofIceDepletion(hr)TimeofContaimentFailure(hr)MaximmUpperCompartmentPressure(psia)MaxirmnUpperCarpartmentTrature('F)CavityHaterLevel9VesselFailure(ft)FractionofCladReactedinVessel()l)HydrogenBurnLocationTotalHydrogenBurned(lb)Outside/InsideCavityEHVIROHMEHTALRELEASEa48hrHobleRelease(X)VolatileFPRelease(X)Hon-VolatileFPRelease(X)1.315x10SLR-S1.947.777.79Hone"'one(g)28.65000.031.5L,U,IU,C498/5440.166.9x101.2x103.558x10SLCJ5.567.6810.013.5>50.76300.033.2L,U,IU,C365/010010.59.5X101.122x10SHC-J1.022.632.6510.615.9>50.75800.032.5L,U,IU387/010029.42.81.578x10SLR'-E5.587.6447.30.020.84600.034.9L,U,IU,C517/91590.50.042.9x100)HOTES:1)Compartments:U~upper,L=Lover,A"-annular,C=cavity,IU=I/Oupperplena.2)Eventdidnotoccurduring48hrs.timeframe.3)Theprimeindicatescontaimentisolationfailure.4)SeeTable4.7-2forasplitbetweenairborneandaqueousrelease.4-71 Page4of6Table4.7-1(Continued)CONTAINMENTSTATUSANDLEVELIISOURCETERMSUMMARYOFDOMINANTSEQUENCESSuenceNo.SequenceFrequencySequenceDesignatorCORE/CONTAINKENTRESPONSETimeofCoreUncovery(hr)Time'ofCoreRelocation(hr)TimeofVesselFailure(hr)TimeofIceOepletion(hr)TimeofContaiwentFailure(hr)KaxinunUpperCompartmentPressure(psia)KaxinunUpperCompartmentTrature('F)CavityMaterLevel0VesselFailure(ft)FractionofCladReactedinVessel()l)HydrogenBurnLocationTotalHydrogenBurned(lb)Outside/InsideCavityENVIRONKENTALRELEASEa48hrNobleRelease()l)VolatileFPRelease(I)Non-VolatileFPRelease(X)5.989x10GHR-C24.7129.6629.68Hone("None(S)22.21700.040.0L,U,IU,C107/5113.50.43.7x10SGR136.600x10GHR-T13.7815.6615.68NoneNone"'0.41540.037.4L,IU,C95/61290.025'8.2X10502.900x10GHMIF-T2.894.344.3614.018.5>50.72600.035.6none0/010066.30.02NOTES:1)Compartments:U=upper,L=lover,A"-annular,C"-cavity,IU"-I/Oupperplein.2)Decontaminationfactor-"7.5-20(forvolatile),11.4-67.5(fornon-volatile).3)Eventdidnotoccurduring48hrs.timeframe.4)SeeTable4.7-2forasplitbetweenairborneandaqueousrelease.4-72 Page5of6Table4.7-1(Continued)CONTAINMENTSTATUSANDLEVELIISOURCETERMSUMMARYOFDOMINANTSEQUENCESSuenceHo.SequenceFrequencySequenceDesignatorCORE/CONTAINXENTRESPONSETimeofCoreUncovery(hr)TimeofCoreRelocation(hr)TimeofVesselFailure(hr)TimeofIceDeletion(hr)TimeofContairmentFailure(hr)HaximmUpperCompartmentPressure(psia)HaximsnUpperCompartmentTrature('F)CavityIlaterLevel8VesselFailure(ft)ISL3.680x10V-T5.686.716.7344.9Hone"'8.82780.0FractionofCladReactedinVessel(X)HydrogenBurnLocationTotalHydrogenBurned(lb)Outside/InsideCavityENVIRONMENTALRELEASEQ48hrHob<eRelease(X)VolatileFPRelease(X)Non-VolatileFPRelease(X)36.2L,C73/6581004.7-12.5<')3.8x10-2.3x10-2<2)NOTES:1)Compartments:U-"upper,L=lo~er,A=annular,C=cavity,IU=I/Oupperplena.2)Decontaminationfactor~7.5-20(forvolatile),11.4-67.5(fornon-volatile).3)Eventdidnotoccurduring48hrs.timeframe.4)SeeTable4.7-2forasplitbetweenairborneandaqueousrelease.4-73 Page6of6Table4.7-1(Continued)CONTAINMENTSTATUSANDLEVELIISOURCETERMSUMMARYOFDOAGNANTSEQUENCESSequenceNo.SequenceFrequencySequenceDesignatorCORE/CONTAINMENTRESPONSETimeofCoreUncover(hr)TimeofCoreRelocation(hr)TimeofVesselFailure(hr)TimeofIceDepletion(hr)TimeofContaiwentFailure(hr)MaximuaUpperCompartmentPressure(sia)MaximmUpperCompartmentTrature('F)CavityWaterLevel9VesselFailure<ft)FractionofCladReactedinVessel(X)HydrogenBurnLocationTotalHydrogenBurned(lb)Outside/InsideCavityENVIRONMENTALRELEASEQ48hrNobleRelease(X)VolatileFPRelease(X)Non-VolatileFPRelease(X)505.779x10THWIF-M12.2314.0314.0524.5727.93>50.72650.042.1None0/08231.61.6x1031907.419x10TKWIFM1.733.293.3114.0625.17>50.75200.033.4L,U,IU,C251/53248.47.5SB01811.970x10THR-S3.333.35None<')None255240.032.5L,U,A,IU489/5130.151.1x103.4x107190"'.903x10THWIF-G3.323.3410.400.018.62400.032.9None0/01005.325.65x10LSP216.27x10THWIFM2.763.963.9814.31>50.77500.038.3L,U,IU,C310/7735.22.6x10NOTES:1)Coayartments:U~upper,L=lover,A~annular,C=cavity,IU=I/Oupperptenua.2)Eventdidnotoccurduring48hrs.timeframe.3)Theprimeindicatescontaiwentisolationfailure.4)SeeTable4.7-2forasplitbetweenairborneandaqueousrelease.4-74 Table4.7-2ENVIRONMENTALRELEASE~'EOUEHCESVesseltoCHTFailureTime(hr)Total()')Airborne()l)948hoursAqueous()l)c)CHTFailureVolatileFissionProductsTotal()l)Airborne(X)948hoursAqueous(X)9CHTFailureHon-VolatileFissionProductsLL0.8HL0.5HLO-35HLO-40SLO-5SL0.35SGR-50SB0.50SBO-190LSP-215.54.08.635.45.813.214.113.921.910.335.716.425.441.710.529.466.331.648.435.27.72.42.47.71.55.447.31.60.46.228.014.023.034.09.024'19.030.048.029.00.120.1016.020.09.5x102.80.021.6x107.52.6x100.120.14.1x108x109.5x10s1.8x109.6x103.3x10S1.0x10SSx103.3x100.016.020.00.02.86.2x101.6x107.52.6x104-75 Table4.7-3RELEASECATEGORYANDPROBABILITYRELEASECATEGORYDEFINITIONSuccessCont.bypassed-<1%volatilesreleasedLatecontainmentfailure-)10%volatilesreleasedContainmentbypassed-)10%volatilesreleasedEarlycontainmentfailure-)10%volatilesreleasedContainmentfailurepriortovesselfailure-)10%volatilesreleasedFREQUENCY5.40E-OS5.99E461.13E461.12E-068.41E478.48E-08P(RCICD).8540.0960.0180.0180.0130.0013NOTE:1.Conditionalprobabilityofreleasecategorygivencoredamage.4-76 Table4.7QANALYSESTOADDRESSUNCERTAINTIESDISCUSSEDINNUREG-1335PhenomenaAnalysesPerformedRelatedMAAPParameter4Performanceofcontainmentheatremovalsystems~Allsourcetermanalysesconservativelyassumedonly1trainofcontainmentspraywithheatexchangerinMAAPanalyses.Nofurthersensitivityanalysisisrequired.~In-vesselphenomena-H>productionandcombustionincontainment~MAAPanalysis(sequenceLLO-5)'usingahighervalueof"flamefluxmultiplier"whichpromotesH~burncompleteness~MAAPanalysis(LLO-5)withandw/ocoreblockagemodelwhichresultsindifferentin-vesselhydrogenproductionFLPHIFCRBLK~Discussedinsummarypaperonhydrogencombustion;sensitivityanalysisisrequired-Corerelocationcharacteristics~MAAPanalysis(LLO-5)withandw/ocoreblockagemodelFCRBLK-Fuel/coolantinteractions~MAAPanalysis(SBO-50)usingreducedcriticalheatfluxFCHF-ModeorRVmeltthrough~DiscussedinsummarypaperonthrustforcesatRPVfailure.Thrustforceswouldnotcausecontainmentfailure;sensitivityanalysisonthrustforcesnotrequired~Allanalysesassumeda60sec.melt-throughtime-InducedfailureofRCSpressureboundaryathighRCSpressure/temperature~SBOsassumedrangeofinducedpumpsealLOCAsfrom96gpmto480gpmperpump.LSP-21assumednosealleakage.Maximumsurgeline/hotlegtemperaturewascalculatedtobe1230'Fofpotentialcreeprupturefailureofhotleg.AnalysisofLSP-21withhotlegfailurewasperformed.4-77 Table4.74(Continued)ANALYSESTOADDRESSUNCERTAINTIESDISCUSSEDINNUREG-1335PhenomenaAnalysesPerformedRelatedMAAPParameter~Ex-vesselPhenomena-Directcontainmentheating(athighRCSpressure)-Potentialforearlycontainmentfailureduetopressureload~AddressedinsummarypaperonDCHasnotcausingcontainmentfailure;nofurtheranalysisisrequired~Earlycontainmentfailuremodesduetoex-vesselsteamexplosionsandhydrogendetonationaddressedinsummarypapersasnotcausingcon-tainmentfailure;nofurtheranalysisisrequired~Earlycontainmentfailure(definedaslessthan6hrsaftervesselfailure)wereanalyzedinbasecasesincludingsequencesLLO-8,MLO-S,SLO-S,SLO-35-Earlyfailureviadebrisattackofcontainmentpenetrations~UncertaintiesaddressedinsummarypaperonPenetrationThermalAttackasnotcausingcontainmentfailure;nofurtheranalysisisrequired-Long-termcoreeoncreteinteraction~DiscussedinMCCIsummarypaperasnotcausingbasematfailurepriortocontainmentoverpressure~Concreteerosiontoseveraldegreesofseverityisacommonphenomenoninbasecasesequences-Wateravailability~Itwasacommonsituationinmostbasecasesthatcoredebrisremaineduncooledinthedrycavity,andforhighpressuresequencesinthelowercompartmentaftercontainmentfailure-Debriscoolability~MAAPanalysis(SBO-50)assumedreduceddebriscoolabilitybyreducingFCHFFCHF4-78 Table4.7-5RANGEOFMAAPMODELPARAMETERSACCORDINGTOEPRITR-100167MAAPParameterRange~TTRX-RVfailuredelaytimeValueUsedintheAnalyses~Allsequenceusedbestestimatevalue,TTRX=60seconds~FCMDCH-FractionofdebrismassthatcontributestoDCH~FCHF-reducefrom0.1to.02~TJBURN-gasjetautoburntemp;increaseto3000K~AllsequencesusedFCMDCH=0.03~SequenceSBO-50performedwithFCHF=0.02.Best~timatevalueforbasecaseswas0.1~Allsequencesusedbestestimatevalueof1060K~FLPHI-flamefluxmultipliercontrollingH>burncompleteness~SensitivityperformedwithLLO-5usedFLPHI=10.BasecasesusedFLPHI=2~FCRDR;increasecore"dump'ractionto0.8todecreasere-vaporizationrate~Revaporizationwasacommonphenomenonaftercontainmentfailureinmostbasecases.Allanalysesconservativelyusedlowvalueof0.1~FCRBLK-coreblockage~LLO-5performedwithandw/oblockagemodel;basecasesconservativelynotusedblockagemodeltoallowmoreHzproduction~TAUTO-raiseautoignitiontempto3000K~Allbasecasesusedbestestimatevalueof983K.Autoignitionwascommoninmostsequenceswithdrycavity.4-79 Table4.7-5(Continued)RANGEOFMAAPMODELPARAMETERSACCORDINGTOEPRTR-100167MAAPParameter~DXHIG-offsetHzmolefractionAnalysesPerformed~Stationblackoutwithnopowerrestorationused'DXHIG=1.0topreventburnwithoutignitionsource~Mostnon-stationblackoutbasesequencesburnedH>atabout6'ithignitersandat8'ithoutignitors~SetvaporpressuremultiplierforCsI,CsOHrevaporizationto0.1~ABB-inducesRCSboundaryfailuresforhighpressuresequence~PCF-containmentfailurepressure~Revaporizationwascommoninmostbasecases~SensitivityanalysisforLSP-21withhotlegcreeprupturefailure~Fragilitycurvedevelopedincontainmentoverpressuresummarypaper,aconservativelowlandfailureofthebasematjunctionwasusedforbasecases.Equipmenthatchfailurewasperformedassensitivity.~ACFPR-recommendusinglargefailurearea~Basecaseanalysesperformedwithsmallbreak(leak-before-break)~Sensitivityanalysesforallsequenceswereperformedwithalargecontainmentfailurestze4-80 Table4.74RangeofAirborneFissionProductReleaseUnderDifferentContainmentFailureScenarios~'mallContainmentBreakSize(0.17ft~)LargeContainmentBreakSize(40fthm)SequencesEquipmentHatchFailureContainmentWaterNotLostt>BasematFailureContainmentWaterLost~>BasematFailureContainmentWaterLost~>LLO-8'LOAOLSP-21SLO-35MLO-5MLO-35SLO-5SBO-50SBO-190Volatile12.52.90.131.7101.01.30.2Non-Volatile0.24x1044x1071x1040.124x1040.13x10~6x104Volatile7.77.76.25.42.42.41.51.60.4Non-Volatile0.108xlo4Sx1072K1040.14x1040.1,3x10~1x10.3Volatile.1012133.45.67.12.72.00.6Non-Volatile0.39x1040.014.6x1040.268xlo40.1873x10~1x103SGR-5030.01xlO~47.31x10247.30.011)oaqueousreease2)SeeavailablefissionproductsforaqueousreleaseinTable4.7-2 Bypass~11s3IsolationFailure0.01Overpressure3.3Figure4.7-1ConditionalProbabilityofContainmentFailurebyFailureMode 0)0 5.0UTKlTYPARTICIPATIONANDINTI<3tNALREVIEWTEAM5.1IPKProgramOrganizationAEPSChascommittedsubstantialpersonnelandfinancialresourcestoitsIPEprogram.Duetothe,magnitudeoftheCookNuclearPlantIPEProgram,AEPSCengagedtheIndividualPlantEvaluationPartnership(IPEP)tosupportanddirecttheanalysiseffortsonthefull-scopeLevelIIIPRAaswellasthetheIPEExternalEventsAnalysis.TheIPEPcompaniesincludeWestinghouse,FauskeandAssociates,andTENERA.AEPSCcreatedaCookNuclearPlantPRATeamwhicheffectivelyutilizesitspersonnelresourcesandprovidesAEPSCwithcompletecontrolandinvolvementintheIPEanalyses.Intheorganizationstructure,IPEPpersonnelprovidedtheoveralltaskleadershipwhileboththeIPEPteamandtheAEPSCteamjointlyperformedalltheanalyses.InteractionsbetweenAEPSCpersonnelandtheIPEPteamwereconductedonacontinualbasisandintensivelyateachsteptoresolveissuesandincorporateplantspecificknowledge.InadditiontotheIPEpersonnel,otherAEPSCengineeringandsupportstaffprovideddesignandoperationalinformationatthedirectionoftheprogramcoordinator.Figure5.1-1depictstheoverallorganizationalstructurefortheAEPSCCookNudearPlantIPEprogram.Asshown,AEPSCestablishedaPRAProjectCoordinatorwhowasresponsiblefortheoverallperformanceoftheIPEprojectandservedastheprimarypointofcontactfortheCookNuclearPlantPRA.FortheCookNuclearPlantIPE,anIndependentReviewTeamofAEPSCmiddlelevelmanagementactivelyreviewedallresultsandinsights.TheAEPSCteammembersweretrainedandinvolvedinallaspectsoftheIPEproject.ThisincludedperformingorreviewingtheLevelI,andexternalevents,reviewingtheLevelIIanalysis,andperformingtheLevelIIIanalysis.TheIPEPorganizationsupportedAEPSCintheCookNuclearPlantIPEprojectwithacoreofexperiencedPRApersonnel,ledbyaTechnicalProjectManager.ThetechnicalprojectmanagerwasresponsibletotheAEPSCProjectCoordinatorfordirectingandcoordinatingprojectactivitiesandmaintainingtheprojectscheduleandbudget.TheprojectmanagerwastheprimaryinterfacebetweentheIPEPteamandtheAEPSCPRAProjectCoordinator.Insummaryform,thefollowingdescribesthetask-by-taskparticipationoftheAEPSCIPEteamengineersinthedevelopmentoftheCookNuclearPlantPRA:DataCollectionandAnalysis-AEPSCengineerscollectedplant-specificdataanddevelopedthedatabaseusedforthesystemsanalysis.InitiatingEventAnalysis-FollowingtrainingbyWestinghouse,AEPSCengineersdevelopedtheinitiatingeventfrequencies,AccidentSequence(EventTree)Analysis-AEPSCco-developedthisanalysiswithWestinghouse.AEPSCengineersalsoperformedthe"special"initiatoranalysis.SystemsAnalysis-AEPSCengineersdeveloped14ofthe19systemnotebookswhichincludedthecreationofthesystemfaulttreemodels.Theremainder,developedbyWestinghouse,wereextensivelyreviewedandapprovedbyAEPSC.HumanReliabilityAnalysis(HRA)-TheHRAandrecoveryactionswereco-developedbyAEPSCandWestinghouse.InternalFloodingAnalysis-Westinghouseperformedthisanalysis.Followingtraining,AEPSCparticipatedintheplantwalkdownandreviewedtheanalysis.5-1 Quantification&SensitivityAnalyses-ThequantificationandsensitivityanalysesweredevelopedbyAEPSCwithtrainingandcontinuedsupportprovidedbyWestinghouse.ContainmentPerformanceAnalysis-FAIwastheleadforthistask.FAIperformedalltheLevelIIanalysis.AEPSCengineersreceivedtrainingontheMAAPcodeandreviewedandapprovedtheLevelIIanalysis.ConsequenceAnalysis-FollowingtrainingbyWestinghouse,theLevelIIIanalysiswasdevelopedbyAEPSCwithcontinuedsupportfromWestinghouse.0'-2 AEPSCPRAPROJECTCOORDINATORIPEPPRATECIINICALPROJECThIANAGERAEPSCPRATEAhIIPEPPRATEAhISYSTEhISANALYSISACCIDENTSEQUENCEEcIIRAINTERNALFLOODINGLEVELIIPRALEVELIIIPRASYSTEMNOTEBOOKSFAULTTREESDATAANALYSISACCIDENTSEQUENCEQUANTIFICATIONINITIATINGEVENTSEVENTTREESURAHALKDOWNSFigure5.1-1CookNuclearPlantIPEProjectOrganization 52CompositionofIndependentReviewTeamAlthoughtheCookNuclearPlantIPEprogramwasperformedtosatisfytherequirementsof10CFR50AppendixB,anadditionalIndependentReviewTeam(IRT)wasorganizedtoreviewtheIPEanalysis.ThisteamgenerallyconsistedofmiddlelevelmanagersfromapplicableengineeringandoperationsorganizationsasindicatedinTable5.2-1.TheIRTconductedformalmeetingstoreview,commentonandapproveallaspectsoftheIPEanalysis.InadditiontotheIRTreviewandtheindependent10CFR50AppendixBreview,theIPEanalysiswasreviewedinternallybyappropriatesystemengineersandoperationsstaffmemberstoensurethatthesystemmodelandassumptionswerecorrectandthefindingsreasonable.

TABLE5.2-1INDEPENDENTREVIEWTEAMREPRESENTATION

DeartmentorDiviinCookNudearPlantOperationsDesignDivisionTitleSupervisorManager,

Structural4AnalyticalDesign,NudearSectionNudearEngineeringDivision-ElectricalManager,Instrumentation8cControl-MechanicalManager,TechnicalSupportNudearOperationsDivisionGroupManager,Safety,Licensing,&AssessmentConsultingEngineer(}ualityAssurance~.5-5 59AnasofRenew,hhgorComments,andResolutifCommAAllareasoftheCookNuclearPlanPlantPRAweresubjecttoindependentreviewthrodixBtheIRToasupporto'i'ernaloledibothItasksd'asks,thePRA.ThisapproachassuredAEPSCinvolvemenaninvolvementinallaspectsoftheCookNuclearHantPRA.Allcommentsandtheirrespectiveresolutionswereformallydocumenteded'echangestothePRAmdIs'ftheffresolutionsanticipatedtohaveaninsignificanteffectonthePRAresuloeieectswereanticipatedtobesinificanperfoeditht'oofthPRA.Majorcommentsandtheirresolutionaresummarized"owmmenN1"Theconclusions[oftheLevelIIanalysis]didnotrorliinoproperlyreflecttheculminationoftheaccident."R~~l~inThisconcernrelatestotheIPEteam'sjudgementthatitisaroriaccidentprogressionduringthefirsttwdsurvithesgnfcantlyslower"postaccident"hase.Theanalsistim~~enpase.eanalysistimeconsideredfortheCookNudearHantlevelthaidtifithoti'fltIb'I't'h>>ies.ecommentor'sconcernswittthehydrogenrecombinersandairrecirItifhdrbeiteddtoIdoitioofththeaccidentislateintheaccidentbed72htitthefftsofthisphenomenAlthh'gedthatthouldbesufflcittimdta.ougitwouldbereferableanmanpowertomaintainreasonablecontrolofthecontainmentnotedthatthNRChastatediAdixCfNUREup.aresult,nochangetotheanalsodelscenariosthatextendoverlongdsf'enoG-1335item6.2Forevaluatingaccidentsequences.~~periootime,thenominalassumptionof24hoursissufficient..."mmnN.2TheviabilityoftheMAAPcodeforuseisanalzihdruseisanyzinghydrogenphenomenawasquestioned.Reels~TheMAAPcodeisaverybroadbased,widelyacceptedcodeusedtoanalzethprovidetheframeworkforunderstandingth'tanningeimportantfeaturesandsstemsandtocalculatetheradionuclidereleasesFh'nalconditionswluchcausecontainmentf'ITh~~~reeases.orthisanalysis,theMAAPaiure.econditionswhichcauseccodeisnotusedtodeterminethebasedonphenomenologicalevaluationscornIdsuthIo.ththdoIdotbelkl~~~ionscompeteusinghandcalculationsandothItiodIitedofthMAAPodfothd'fthMAAPforitsmorewidelyaccepteduse,wheretheaccuracofuse,wereteaccuracyofthehydrogenmodellingisofsecondaryimportance.

mmn"TheanalysesunderpredicttheimpactoFsevereaccidentgeneratedhydrogenonthecontainmentintegrity."Thiscernprimarilyinvolvesthepossibilitythatcontainmentcouldfailduetoahydrogenpressurespikeconcernprimeitherduetothelossofthecontainmentairrecirculationfansorduetodetonabons.Thecontainmentaiurmodesweredeterminedbyphenomenologicalevaluations.Containmentfailureduetohydrogencombustionwasshowntobeimprobablebecausetheconditionsnecessarytogeneratesuflicienthydrogenandtoaccumulateitintheproperlocationtocausecontainmentfailurewouldnotlikelyexist.Shouldthosedit'uchmorelikelythatcontainmentwouldhavepreviouslyfailedduetoconditionsexit,>tismumorei~~~~~~~~overpressurizationcausedbysteaming.Thephenomenologicalevaluationsupportingthispos>bonasvahdwhetherornothydrogenrecombinersand/orairrecirculationfansareoperating.Thepossibilityofdetonationwasfoundnegligiblebyamanualevaluation."TheanalysisfailstoidentifyvulnerabilitiesthatareuniquetoCookPlant."Thisconcernisrelatedtothecommentor'spositiononcomments2and3.Thecommentorbelievesthat,sincethereisatleastuncertainty'inwhetherhydrogencandirectlycausecontainmentfailure,thesurvivabiliyoequipmentusedtocontrolhydrogenshouldbeaddressedasavulnerability,particularlythecontainmentairrecirculationfans.SincetheIPEteam'spositionisbasedonanevaluationwhichshowsthatitisunlikelythasufficienthydrogencanbegeneratedandaccumulatedintheproperlocationtocauseahydrogenburnofsufficientmagnitudetochallengecontainment,withoutsomeothermeclmnismcausingcontainmentfailure,itwasnotappropriatetoconsidertheairrecirculationfan'ssurvivabilityasavulnerabilityfromasevereaccidentperspective."ThePRAshouldconsiderhighenergylinebreaksoutsideofcontainment..."Thisconcernisduetothecommentor'sbeliefthatahighenergylinebreakoutsidecontainmentwillresultinadifferentaccidentprogressionthanasteamlinebreakinsideofcontainment,theaccidentmodelledintheIPEtoboundallhighenergylinebreakaccidents.ThedifferentaccidentprogressionwouldoccurbecausethehighenergylinebreakcoulddestroyequipmentintheimmediatevicinityofthebreakorequipmenneededtomitigatetheaccidentiFitisnotqualifiedfortheenvironmentalconditionscausedbythehighenergylinebreak.ThisconcernwasaddressedbytheIPEteaminthreeareas:I)initiatingeventfrequency,)accidentprogression,and3)equipmentsurvivability.Thesearediscussedinmoredetailbelow.TheinitiatingeventfrequencyfortheIPEforlargesteamline/feedlinebreakeventsincludesconsiderationoffailuresbothinsideandoutsidecontainment.Ifhighenergylinebreaksoutsidecontainmentweretobemodelledseparatelyfromhighenergylinebreaksinsideofcontainment,thentheinitiatingeventfrequencyforeacheventwouldbelessthanthevalueusedwhentheeventsareconsideredtogether.Further,whenconsideringonlythosebreaklocationsoutsideofcontainmentthatareinthevicinityofequipmentmodelled5-7 hinthesteamhne/feedImebreakanalysis,theinitiatingeventfrequencywouldbesigniTicantlylowerthanthatWithrespecttotheaccidentprogression,ahighenergylinebreakinsidecontainmentmodelsallthoeequipmentw'ouberequiredtomitigateahighenergylinebreakeventoutsidecontainment.Becauseoftrainseparationofmostofthemodelledequipmentitwasconsideredunlikelythatapostulatedbreakoutsideofcontainmentwouldbeindoseproximitytomorethanonetrainofequipment.Theimpactonaccidentprogression,therefore,wasnotconsideredtobesignificant.Hnally,theIPEteamreviewedthelistofenvironmentallyqualiTiedequipmentandfoundthatallmoorequipmentmodelledintheaccidentwasqualifiedfortheconditionsexpectedtoresultfromahighenergylinebreakoutsidecontainment.5.4LivingPRAProgr:unTheCookNuclearPlantPRAisdesignedtobeperiodicallyupdatedovertheremaininglifetimeoftheplantbyutilityriskassessmentandengineeringpersonnel.ThelivingPRAprogramwilladdressappropriateplantdesignandoperatingchangesthatoccur.TheCookNuclearPlantPRAmaybeusedtovaryingdegreesfornuclearplantsupportinmanydifferentareassuchas:~Operatortraininginriskdominantsequences.~Safetyevaluations.~~~Establishmentofequipmentsurveillancetestintervals.~PrioritizationoFimportantequipmentandsystems.Establishmentofallowableoutagetimes(AOT)inTechnicalSpecificationsForsafetyrelatedequipment.

6.0PLANTIMPROVEMENTSANDUNIQUESAH'"IVFEATURESForCookNuclearPlant,theresultsofthePRAindicatethattherearenomajorsevereaccidentvulnerabilitiesthatrequireimmediatecorrectiveaction.AEPSCiscurrentlyinvestigatingpossiblemodificationstoproceduresandcomponentswhichweredominantcontributorstocoredamagefrequency.Thesemodificationsinclude:addedemphasisonRCPsealtemperatureintheemergencyoperatingprocedures.FailuretotriptheRCPsfollowingtheinitiationoftheaccidentwasfoundtobeadominantcontributorintheLossofCCWandaLossofESWevents.instructiontoopentheCVCScross-tievalvetotheoppositeunitearlyintheaccidentresponse.FailureofRCPsealcoolingwasfoundtobeasignificantcontributortocoredamagefrequencyintheLossofCCWandLossofESWevents.TheinitiationofchargingflowfromtheoppositeunitshouldprovidesufficienRCPsealcoolingtopreventsealdamage.modificationstothecompressedairsystem(Unit1controlaircompressor)"toincreasethecapacityofthesystem.Failureofthecompressedairsystemwasfoundtobeasignificantcontributortocoredamagefrequency.Eventhoughacceptableeventtreemodelingmodificationswouldlowercompressedaircontributionsandvirtuallyeliminatethisvulnerability,AEPSCiscurrentlyevaluatingcostbeneficialupgradestothecapacityoftheUnit1controlaircompressor.operatortrainingontheimpactofprimaryandsecondarysystemheatremovaloncontainmentpressureresponseandthepossibilityofcontainmentfailureprecedingcoremelt.Inaddition,proceduralupgradeswillbeconsideredtominimizethepossibilityofsuchsituationsarising.modificationstotheEOPstoinstructtheoperatorstomaintainfeedwaterflowtothefaultedsteamgeneratorduringasteamgeneratortuberuptureeventwhensecondarysideintegritycannotbemaintained.ThishasasignificantaffectonreducingoffsitereleasesduringaSGTRwithastuckopensteamgeneratorsafetyvalveorPORV.operatortrainingontheimportanceofawetreactorcavityonpotentialfissionproductreleases.ThistrainingwillemphasizeinjectingthemaximumamountofwaterpossiblefromtheRWSTtothecontainmentpriortoswitchovertorecirculation.ThemajorfactorsaffectingthesafetyofCookNuclearPlantwereidentifiedas:Twomotor-drivenandoneturbine-drivenauxiliaryfeedwaterpumps,whichformostaccidents,providethreeredundantheaders.Theabilitytocross-tieauxiliaryfeedwaterflowfromtheoppositeunit,thusaffordingadditionalredundancyinthatsystem.AveryreliableoffsiteelectricpowergridthatreducesthelikelihoodoflossofoffsitepowerandstationblackouteventsatCookNuclearPlant.Theabilitytocross-tiecomponentcoolingwaterfiowfromtheoppositeunit,thusaffordingadditionalredundancyinthatsystem.Thecontainmentultimatefailurepressureoverthreetimesdesignpressurewitha95/95confidencelevel.Containmentultimatefailurepressureisalmostfivetimesdesignpressureascomparedtothemedianfailurevalue.6-1 Operationofcontainmentspraysintherecirculationcanbeexpectedtopreventcontainmentfailureforpracticallyallaccidents.Anessentialservicewater(ESW)system,sharedbetweenbothUnits,thatoperateswiththeUnit-to-Unitcross-tievalvesopen.ThisallowsoneUnittoreadilyrelyonESWflowfromtheoppositeUnit.~'"'-2 7.0SUMlÃtGKYANDCONCLUSIONSAEPSChasperformedaLevelIIIProbabilisticRiskAssessmentofinternallyinitiatedeventsfortheDonaldC.CookNuclearPlant.Thisstudywasperformedusingafaulttreelinkingmethodologyandmeetstherequirementsof10CFR50AppendixB.TheCookNuclearPlantPRAdocumentsthecomputermodelsandtheresultsoftheanalysis.WhiletheIndividualPlantEvaluationPartnership(IPEP)wascontractedfortheCookNuclearPlantPRA,AEPSCpersonnelwereinvolvedtoagreatdegreeineveryaspectofthisanalysisthrougheitherdetailedreviewofcontractworkoractualperformanceoftheanalysis.ThecontractwithIPEPincludesacompletetransferoftechnology.ThistechnologytransferallowsAEPSCtobiannuallyupdatetheCookNuclearPlantPRAin-housewithoutadditionalcontractwork.ResultsofthePRAindicatedthatthecoredamagefrequencyforinternaleventsis6.26E-5peryear.TheexaminationhasidentifiedthattheinitiatingeventwiththelargestcontributiontocoredamagefrequencyisSmallLOCA(SLO)witha47%contribution.FailureoftheEmergencyCoreCoolingSystem(ECCS)duringeitherthecoldleginjectionorrecirculationphasesproducedthetwomostdominantsequencesforthisevent.Commonmodefailureofthesafety(Si)pumps(partoftheECCS)andfailureoftheEngineeredSafetyFeatures(ESF)systemtoactuatetheECCSdominatedthesetwosequences.Thethirdleadingsequenceresultedfromfunctionalfailurestocoolthereactorcoolantsystem(RCS)followedbyfailureofprimarybleedandfeedcooling.Hardwareandcommonmodefailuresinthecompressedairsystem,whichsuppliesairtothepressurizerandsteamgeneratorPORVs,contributedmostlytothesefailures.TheLossofComponentCoolingWater(CCW)event,whichcontributed22%tothecoredamagefrequency,wasdominatedbythreesequences.Thefirstsequencewassolelydominatedbythefailureoftheoperatortotriptherunningreactorcoolantpumps(RCPs)aftersealcoolingfromCCWislost,thusleadingtogrosssealfailure.ThesecondsequencewasdominatedbyfailureofECCScoldlegrecirculationduetocommonmodefailureoftheSIpumps.ThethirdsequencewasinvolvedthefunctionalfailuretorestorereactorinventoryafterCCWwasrestored(whichthenrestorestheECCSchargingpumps).ThisfailurewasdominatedbyoperatorerrorandESFsignalfailure.JTheSteamGeneratorTubeRupture(SGTR),comprising11%ofthecoredamagecontribution,involvedmultiplesequencesofsignificantcontribution.ThedominantfailuresassociatedwiththesesequenceswerehardwareandcommonmodefailuresofthecompressedairsystemandfailuresofESFsignals.Failureofthecompressedairsystempreventedremotecooldownand"depressurizationoftheRCStherebyallowingreactorcoolantinventorytobelosttothesecondarysideofthesteamgeneratorsuntilthereisnotsufficientreactorcoolantinventoryremainingtotransferheatfromthecore.ThesignificanceoftheSGTReventisthatcontainmentmaybedirectlybypassedandfissionproductsreleaseddirectlytotheenvironmentfollowingcoremelt.Allotherinternalinitiatingeventswereverysmallcontributorsanddisplayednosignificantvulnerabilitiesinadditiontothosepreviouslydiscussedinthissection.Thereduridancyaffordedbytheauxiliaryfeedwatersystem(twomotor-drivenpumpsandoneturbine-drivenpump)issignificantlybeneficialforthetransientevents.Theextremelyreliableelectricpowergrid,ofwhichCookNuclearPlantisapart,greatlyinfluencedtheinitiatingeventfrequenciesfortheLossofOffsitePowerandStationBlackoutevents,thusdirectlyinfluencingtheirsmallcontributionstocoredamagefrequency.Failuresduetocommoncauseweredominantcontributorsinalmosteveryinitiatormodeled.Thereasonthatcommoncausesooftenappears,however,isduetothemodelingapproach.Thesystemfaulttreestypicallymodeledcommoncausefailuresfortheentiresysteminasinglegate.Thistreatedallcommoncausefailures,whetherforpumps,valves,oranyothercomponent,asasinglefailure.Iftheindividualcomponentcommoncausecontributionshadbeenmodeledinindividualgates,theoverallcommoncausecontributiontocoredamagefrequencywouldhavebeengreatlyreduced.Itwasconcluded,therefore,thatcommoncausefailuresarenotadominantcontributortocoremeltfrequency.ThefirststepinthelevelIIanalysiswastodeterminethepossiblefailuremodesfor'heCookNuclearPlantcontainment.Thisanalysisshowedthattheoverpressurefailureforthecontainmentwouldmostlikelyoccur7-1 duetoshearoftheconcretebasematatthecylinderbasematjunction.Thisfailuremodecauseswaterinthecontainmenttobelostandasubsequentlossoflongtermrecirculationcooling.Inaddition,thisfailuremodeeliminatesmanypostcontainmentfailureaccidentmanagementstrategies.Theconditionalprobabilityofcontainmentfailureonoverpressuregivencoremeltisonly0.033.Eventhoughthisfailureprobabilityissmall,thefailuremechanismmayprecludepostcontainmentfailurerecoveryandaccidentmanagementactionsbecausethecontainmentfailuremaycausefailureofpipingandelectricalconnectionstothecontainment.Theoverallfrequencyofcontainmentfailurewasfoundtobesmallat9.1ECperyear.Giventhatacoremeltaccidenthasoccurred,thereisapproximatelyan85%chancethatcontainmentintegritywillbemaintained,Asindicat'edabove,containmentfailureonoverpressurizationlsexpected3.3%ofthetimefollowingcoremelt.Thedominantcontainmentfailuremodefollowingcoremeltwasfoundtobecontainmentbypassfollowingasteamgeneratortuberupture.0:Theprobabilityofcontainmentfailureduetohydrogencombustionwasalsoevaluatedaspartofthelevel.IIPRA.Thisanalysisshowedthat,foranycrediblescenario,thechanceofthecontainmentfailingduetohydrogencombustionwasunlikely.Itwasdeterminedthatitwasimprobablethatsufficienthydrogencouldbegeneratedduringthetimeperiodwhenhydrogenigniterswereunavailablesothatahydrogenburncouldfailcontainment.Forthosesequenceswheresufficienthydrogencouldtobegeneratedsothatahydrogenburncouldfailcontainment,itismuchmorelikelythatcontainmentwouldhavealreadyfailedduetooverpressurization.Supplement3toGenericLetter88-20(Reference9)requestedanevaluationofthevulnerabilityoficecondensercontainmentstotheinterruptionofpowertohydrogenigniters.Itisconcluded,assummarizedintheabovediscussion,thattheinterruptionofpowertothehydrogenignitersdoesnotconstituteavulnerabilityoftheCookNuclearPlantContainment.Asaresult,providingabackupDCpowersupplytothehydrogenigniterswouldnotprovideanynoticeabledecreaseinthefrequencyoroffsiteconseq'uencesofcontainmentfailureoftheCookNuclearPlant.UsingcontainmentatmosphericreleasesourcetermsfromtheLevelIIanalysis,offsiteconsequenceswerecalculatedusingtheMELCORAccidentConsequenceCodeSystem(MACCS),Reference14.TableA-1presentstheresultsfortheoverallcombinedeffectsofthethreeevacuationschemes(evacuation,noevacuationandacombinationofevacuationandsheltering)andthelongtermeffects.AsshowninTableA-1,theSGR50sequence(steamgeneratortuberupture)sourcetermsdominateearlyandcancerfatalitiesandwholebodydoses.SGRSOisacontainmentbypasssequenceforwhichthecontainmentalsofailsonoverpressure.Virtuallyallofthenoblegasesand)10%ofthevolatilefissionproductsarereleasedfromcontainment.SGR50containmentbasematfailureyieldedthemostcancerfatalitiesandSGR50uppercontainmentfailure(equipmenthatchfailure-LevelIIsensitivity)yieldedthemostearlyfatalities.FiguresA-1throughA4presentearlyfatalities,cancerfatalitiesandwholebodydosesat50milesand100milesforSGR50.FigureA-3,populationdoseupto50miles(meanvaluecurve),iscomparabletopopulationdosesupto50milesfortheSurry,SequoyahandZionplantsinNUREG-1150(Reference66),whichalsousedtheMACCScode.FiguresA-1,A-2andAAcouldbecomparedtoNUREG-1150,however,NUREG-1150evaluatedsiteregionsupto1000mileswhereasthisprojectevaluatedupto100miles.ToaddresstheexpectedconsequencesofSGR50,aprocedurechangeisunderinvestigationtomaintainsteamgeneratorlevelintheeventofthisaccident.Thismodificationisexpectedtogreatlyreducetheoffsitedoseconsequencesofthissequence.0'TheCookNuclearPlantPRAwasdevelopedtomeettherequirementsof10CFR50AppendixB.ThisapproachforceddetailedreviewbeyondthataddressedinGenericLetter88-20(Reference9).AEPSCisconfidentthatthisanalysisadequatelymeetstheintentofGenericLetter88-20,includingSupplements1and3.Nomajorplantvulnerabilitieshavebeenidentifiedwhichrequireimmediateactionorsignificanthardwarechanges.Changestobothproceduresandhardware,however,arebeingconsideredtoaddressminorvulnerabilities.TheseareidentifiedinSection6.0.ItistheintentionofAEPSCtousetheCookNuclearPlantPRAasadecision-makingtoolinmanyaspectsofengineeringsupportandplantoperations.SincethePRAisahighlytechnicaldocumentanduncertainties7-2 doexistintheanalysis,theuseandinterpretationofPRAresultsandconclusionsiscurrentlylimitedtothoseindividualswhohavebeenintimatelyinvolvedwithitsdevelopment.Thisapproachavoidstheproblemsthatmightarisefrommisinterpretationofthestudy.Also,AEPSC'sinternalcommitmenttoregularlyupdatethePRAensuresthatthedocumentwillbea"living"documentthatadequatelyrefiectsthecurrentplantconfigurationandoperatingrequirements.This"living"PRAconceptcoupledwiththereviewrequirementsof10CFR50AppendixBmakestheCookNuclearPlantPRAavaluabledecision-makingtoolformostsafetyrelatedquestions.7-3 0)1T0,

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APPENDiXAOFFSITECONSEQUENCESANALYSIS(LEVELIII.PRA) l11>II~>vj>II~dj~vrt~,I,'d~~,,'lfpILI~<<I=lt-.;-'-l'~I~~vdIjl~I"jS,,ldVI~C,~~t<<~iI<<-III11'I<<III~I'v'I)>~1~v~Iv~I1IIII~t'PV'I"VjI'~~I'IL>II~f~%Pj~>I"1';>II111,>$>>>l't-v.I'IIIPJ~~-lI'v,~)I'tVtj~Pj<<-t'l.l'~d<<II'<<<<14I),l(e'"l;"'I~~1~1lrIJJjIIIld>r~Il<<II~-I APPENDIXAUsingcontainmentatmosphericreleasesourcetermsfromtheLevelIIanalysis,offsiteconsequenceswerecalculatedusingtheMELCORAccidentConsequenceCodeSystem(MACCS),Reference14.TableA-1presentstheresultsfortheoverallcombinedeffectsofthethreeevacuationschemes(evacuation,noevacuationandacombinationofevacuationandsheltering)andthelongtermeffects.AsshowninTableA-1,theSGR50sequence(steamgeneratortuberupture)sourcetermsdominateearlyandcancerfatalitiesandwholebodydoses.SGR50isacontainmentbypasssequenceforwhichthecontainmentalsofailsonoverpressure.Virtuallyallofthenoblegasesand)10%ofthevolatilefissionproductsarereleasedfromcontainment.SGR50containmentbasematfailureyieldedthemostcancerfatalitiesandSGR50uppercontainmentfailure(equipmenthatchfailure-LevelIIsensitivity)yieldedthemostearlyfatalities.PlantconditionsrepresentedbySGR50are:reactorcoolantsystemathighpressure,refuelingwaterstoragetanknotemptied(containmentsprayandhigh/lowheadchargingdrawfromit),hydrogenignitersandcontainmentairrecirculationfansfailed.FiguresA-1throughAQpresentearlyfatalities,cancerfatalitiesandwholebodydosesat50milesand100milesforSGR50.Theresultsinthesefiguresaccountforcoredamageandcontainmentfailureprobabilities(fromTable4.7-3)associatedwithSGR50.TheresultsinTableA-1donotaccountforcoreandcontainmentfailures,butonlypresentresultsofsourcetermreleases.FigureA-3,populationdoseupto50miles(meanvaluecurve),iscomparabletopopulationdosesupto50milesfortheSurry,SequoyahandZionplantsinNUREG-1150(Reference66),whichalsousedtheMACCScode.FiguresA-1,A-2andA4couldbecomparedtoNUREG-1150,however,NUREG-1150evaluatedsiteregionsupto1000mileswhereasthisprojectevaluatedupto100miles.FThecontainmentreleasesourcetermsselectedasinputintotheLevelIIIanalysisarerepresentativeofthecontainmentreleasecategoriesfound,inTable4.7-3.Ofthecontainmentbypasscategories("C"and"T"),itwasdecidedthatcategory"T"wouldbeanalyzedforoffsiteconsequences.SourcetermSGR50representscategory"T"andreleasedvirtuallyallofthenoblegasesandapproximately47%ofthevolatilenuciides.Thisvolatilereleaseissignificantlygreaterthanthe(1%volatilereleaseincategory"C".Also,eventhoughcategory"C"hasahigherfailureprobability,thefailure'valueisinthesameorderwf-magnituderangeascategory"T".Forthecontainmentbasematfailuresourceterms,allofthenoblegases,mostofthevolatileandanoticeableamountofthenon-volatilefissionproductsescapedthecontainmentstructure.However,asshownintheCookNuclearPlantUFSAR,(Reference1),thecontainmentbasemat(annulus)is21feetbelowgrade(gradeis608ft.andtheannulusisat587ft.).WithinIDCORTechnicalReport18.1(Reference65),whichdealtwithatmosphericandliquidpathwaydoses,itwasconcludedthatforbasematfailuresduetoreactorfuelmelt-through,onlysmallpopulationdoseswouldbeexpected.Interdictiyemeasureswouldbeneededintheworstcases.TheseconclusionswerereachedusingtheMAAPcode(whichLevelIIused)andtheCRAC2code.Therefore,liquidpathwaydosesarenotconsideredinthisproject.

TABLEA-1LevelIIIOffsiteConsequenceResultsACCIDENT~EUEN(EFATALITIES(MEANVALUES)EARLYCANCERWHOLEBODYDOSES(REM-MEANVALUES)SBOI8180.00E+00SGR50~~MLO40~~~1.77E+000.00E+00SLO35SGR50~ISL5jc0.00E+00~1.13E+021.82E-03MLO40~".-.0~00E+00LL08~4:.-0.00E+001.41E-0I,"2.68E+032.05E+034.59E+031.13E+033.32E+023.58E+032.09E+034.04E+02;2.74E+053.05E+058.19K+051.87E+051.35E+052.89E+063.72E+052.43E+06L92k+064.84E+061.20E+064.29E+055.49E+062.12E+06l.'56E+071.21E+072.65E+076.55E+061.92E+061.94E+071.21E+075.03E+02";--8.18E+02Nocontainmentfailure.MLO40andSGR50LevelIlsensitivitystudieswithfailureinuppercontainment.~~Containmentbasematfailuresourceterms.

'1.000E"06PROBABILITYOFOCCURRENCEI.OOOE-07~*~C.OOOE-08~r~~u'~e~4.000E"09O.oa~0.03'='.11'-10'OTALEARLY-FATALITlES100FigureA-1SGR50EarlyFatalities0-100Milesll'IfA-3 I~,ll~'llI'I~I4'IIt'Ip"I414'Il4IAllIIIII,4(l(I'I~$4I'I,"Ill(IgalJIllIII'Ig)'.).,II~

1.00E-06PROBABlLITYOFOCCURRENCE1.00E-061.00E-071.00E-081.00E"09:.OOE,101.00E+041.00E+061.00E+061.00E+071.00E+08-1.00E+09PopULATioNDosE(PERsoN-REM)To~ooMi.~~FigureAASGR50PopulationDose(Person-REl4to100to100Miles C.l-~e'4C',~1rofrrIIP~t~~(a)~~rirtrt~~t/Att'Itj11IIPP~1~I~t~II I.OOE-06PROBABlIITYOFOCCURRENCE1:OOE=06I.OOE;0.71.00E"08'.00F09,.00I;OOE+041.00E+06.I.0OE+061.00E+07I.OOE+08POPULATION:DOSE(PERSON-REM)-'TO60-MILESFijureA-3.SGR50PopulationBose(Person-REM)to50.MilesA-5

~Ig~tttt~IW'3lg~II~~'tIt~~ttJ~~~'IJ)t.1lIttrJ,,**~{1t~~tPI~~l 1.000E-05PROBABlLlTYOF-OCCURRENCE1.000E-061.000E-071.000E-081.000E-0910100100010000-100000TOTAL-CANCERFATALITIESFigureA-2SGR50CancerFatalities0-100hliles/

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