ML17326A077

LER 98-029-01:on 980422,noted That Fuel Handling Area Ventilation Sys Was Inoperable.Caused by Original Design Deficiency.Radiological Analysis for Spent Fuel Handling Accidents in Auxiliary Bldg Will Be Redone by 990830

ML17326A077
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Issue date:	08/04/1999
From:	BERRY L R INDIANA MICHIGAN POWER CO.
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ML17326A076	List: 05000315/LER-1998-029-01, Forwards LER 98-029-01, Fuel Handling Area Ventilation Sys Inoperable Due to Original Design Deficiency. Supplemental Rept Represents Extensive Rev to Original LER & Replaces Rept in Entirely.Commitment Listed
References
LER-98-029, NUDOCS 9908100140
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NRCFORM366U.S.NUCLEARREGUYCOMMISSION(6-1996)LICENSEEEVENTREPORT(LER){Seereverseforrequirednumberofdigits/charactersforeachblock)APPROYOMBNO.3150-0104EXPIRES06/30/2001Estimatedburdenperresponsetocomplywiththismandatoryinformationcollectionrequest:50hrs.Reportedlessonslearnedareincorporatedintothelicensingprocessandfedbacktoindustry.ForwardcommentsregardingburdenestimatetotheRecordsManagementBranch(TAF33).U.S.NuclearRegulatoryCommission.Washington.DC205550001,andtothePaperworkReductionProject(3t500104).05ceofManagementandBudget,Washington.DC20503.IfaninformationcollectiondoesnotdisplayacurrentlyvalidOMBcontrolnumber.theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformationcollection.FACILITYNAME(1)CookNuclearPlantUnit1DOCKETNUMBER(2)05000-315PAOE(3)1OF4TITlEI4IFuelHandlingAreaVentilationSystemInoperableDuetoOriginalDesignDeficiencyEVENTDATE{5)LERNUMBER{6)REPORTDATE{7)OTHERFACILITIESINVOLVED{6)MONTHDAYYEARYEAR1998SEQUENTIALNUMBERREVISIONNUMBERMONTHDAY199FACILITYNAMECookNuclearPlantUnit2FACILllYNAMEDOCKETNUMBER05000-316DOCKETIIUMBEROPERATINGMODE(9)POWERLEVEL(10)20.2201(b)20.2203(a)(1)20.2203(a)(2)(i)20.2203(a)(2)(ii)20.2203(a)(2)(iii)20.2203(a)(2)(iv)20.2203(a)(2)(v)20.2203(a)(3)(i)20.2203(a)(3)(ii)20.2203(a)(4)50.36(c)(1)50.36(c)(2)50.73(a)(2)(i)50.73(a){2)(ii)50.73(a)(2)(iii)50.73(a){2)(iv)50.73(a)(2)(v)50.73(a)(2)(vii)DPURSUANTTOTHEREOUTHISREPORTISSUBMITTEIREMENTSOF10CFRE:(Checkonoormore)(11)50.73(a)(2)(viii)50.73(a)(2)(x)73.71OTHERSpecifyinAbstractbeloworinNRCForm366ANAMELICENSEECONTACTFORTHISLERLyleR.Be(Ty,ComplianceEngineer{12)TELEPHONENUMBERIIndudeAreaCode)(616)465-5901x1623COMPLETEONELINEFOREACHCOMPONENTFAILUREDESCRIBEDINTHISREPORT{13)CAUSESYSTEMCOMPONENTMANUFACTURERREPORTABLE"ToEPIXCAUSESYSTEMCOMPONENTMANUFACTURERREPORTABLEToEPIXSUPPLEMENTALREPORTEXPECTED14YES{Ifyes,completeEXPECTEDSUBMISSIONDATE).XNOEXPECTEDMONTHDAYYEARABSTRACT(Limitto1400spaces,i.o.,approximately15single-spacedtypewrittenlines)(16)OnApril22,1998,duringpreparationoftheRadiationMonitoringSystemDesignBasisDocument(DBD),itwasidentifiedthattheresponsetimeoftheFuelHandlingAreaVentilationSystem,fortransitionfromthenormaltotheemergencyfiltrationmode,maynotbeadequatetopreventanunfilteredreleasefromarefuelingaccidentoutsidecontainment.Currentoff-sitedosecalculationsassumefiltrationforanaccidentintheAuxiliaryBuilding.ThisconcernwasidentifiedbycontractorpersonnelreviewingastatementmadeinresponsetoNRCQuestion9.4fortheSAR.Thisquestionrequesteddesigndetailstodemonstratethattheresponsetimeofthecharcoaladsorberbypassdamperwasadequatetopreventapotential"puffrelease"totheenvironmentafterahighradiationsignalwasreceived.Afterresearchingexistingdocumentationandperformingascopingcalculation,itwasdeterminedthattheresponsetimeofthebypassdamperdescribedinreplytotheSARquestionwasinadequatetopreventanunfilteredrelease.Areleasefromarefuelingaccident(droppedfuelbundle)intheSpentFuelPoolwascalculatedtoreachthebypassdamperbeforeinitiationofcharcoalfiltration.Consequently,sincetheFuelHandlingAreaVentilationSystemhadbeendeterminedtobeincapableofperformingitsspecifiedfunction,itwasdeclaredinoperable.Sincethisconditionwaspreviouslyunknown,nocompensatoryactionshadbeenhistoricallytaken.TheFuelHandlingAreaVentilationSystemiscommontobothunits.OnMay27,1998,thisconditionwasdeterminedtobereportablepursuanttotherequirementsof10CFR50.73(a)(2)(i)(B),asoperationorconditionprohibitedbytheplant'sTechnicalSpecifications.Therootcauseofthisconditionisadesigndeficiency,whichhasbeenpresentsinceplantconstruction.Evaluationofthisconditionhasdeterminedthatevenwithoutthecharcoalbedinservice,theconsequencesofapostulatedfuelhandlingaccidentarewellwithin10CFR100limits.Baseduponthisinformation,thiseventhadminimalimpactonthehealthandsafetyofthepublic.9908iOOi40990804PP"ADCICK0500/13i5

NRCFORM366AU.S.NUCLEARADULATORYCOMMISSION16-1998)LICENSEEEVENTREPORT(LER)TEXTCONTINUATIONFACIUTYNAMEI1)DocKETI2)LERNUMBERI6)PAGEI3)CookNuclearPlantUnit105000-315YEARSEQUENTIALNUMBER2OF4NUMBER199802901TEXT/Ifmorespacoisreriuired,usoadditionalcopiesofNRCRearm366AII17)ConditionsPriortoEventUnit1Mode5,ColdShutdownUnit2Mode5,ColdShutdownDescritionoftheEventOnApril22,1998,duringpreparationoftheRadiationMonitoringSystemDesignBasisDocument(DBD),itwasidentifiedthattheresponsetimeoftheFuelHandlingAreaVentilationSystem(EIIS:VG),fortransitionfromthenormaltotheemergencyfiltrationmode,maynotbeadequatetopreventanunfilteredreleasefromarefuelingaccidentoutsidecontainment.Currentoff-sitedosecalculationsassumefiltrationintheAuxiliaryBuilding.ThisconcernwasidentifiedbycontractorpersonnelreviewingastatementmadeinresponsetoNRCQuestion9.4(Amendment20,March,1972)fortheSAR.Thisquestionrequesteddesigndetailstodemonstratethattheresponsetimeofthecharcoaladsorberbypassdamper(EIIS:VG/CDMP)wasadequatetopreventapotential"puffrelease"totheenvironmentafterahighradiationsignalwasreceived.TheresponsetoSARQuestion9.4wasasfollows:"Exhaustedairfromthespentfuelpitwillreachthecharcoalfilterbypassdampersin4seconds(basedontheshortestpath).Thetimeelapsedfromreceivingahighradiationsignalattheradiationmonitortothefullshutpositionofthecarbonfilterbypassdamperislessthan3seconds.Theinvestigationrevealedthatthereislittle'existingdocumentationonthisoriginaldesignfeature.Afteranextensivesearch,itwasdeterminedthatnoinformationcouldbelocatedwhichsupported,orprovidedabasisfor,thestatementintheSARQuestion9.4response.AscopingcalculationwasperformedforthetimeexpectedforareleasefromtheSpentFuelPooltoreachthedampers.Thiscalculationindicatedthattheairtransittimewasfessthan1second,whichislessthanthe3secondresponsetimeforthecombinationofradiationmonitoractuationandbypassdampermovement.Sincenotestdatacouldbelocatedtodemonstratethatthetransitiontotheemergencyfiltrationmodewasrapidenoughtopreventarelease,thesystemwasconsideredtobeinoperable.TheFuelHandlingAreaVentilationSystemiscommontobothunits.CauseofEventThisconditionisattributedtoadeficiencyintheoriginaldesign.Asnodocumentationoftheoriginalpostulatedairtransporttimeversustimefordamperoperationcouldbelocated,itwasnotpossibletoreconstructthedesignbasisforradiationmonitoractuationoftheemergencyfiltrationmodeforthesystem'.AnalsisofEventOnMay27,1998,withbothUnit1andUnit2inMode5,itwasconcludedthatthiseventwasreportableunder10CFR50.73(a)(2)(i)(B),asanoperationorconditionprohibitedbytheplantTechnicalSpecifications.ThisconclusionwasreachedbecausetheFuelHandlingAreaVentilationsystemwasinoperablefromtimeofplantstartupandhasremainedinoperable.TechnicalSpecification3.9.12,.whichprohibitsfuelmovementwiththesysteminoperable,wasviolatedwheneverfuelwasmovedwithoutthecharcoalfilterbeinginservice.Theoriginaldelayindeterminingthereportabilityofthisconditionwasprimarilyduetothescarcityofinformationpertainingtothisdesignfeature.NRCFORM366AI6-1996)

NRCFORM366AU.S.NUCLEARREGULATORYCOMMISSION(6.1999)LlCENSEEEVENTREPORT(LER)TEXTCONTINUATIONFACILITYNAME(1)CookNuclearPlantUnit1DOCKET(2)05000-315YEARLERNUMBER(6)PAGE(3)SEQUENTIALREVISION3QF4NUMBERNUMBER199802901TEXTiifmorespaceisrequired,useadditiorIalcopiesofIVRCForm366AJ(17)Nodocumentationor.calculationcouldbefoundtosupporttheresponsetimeandairtransittimesreportedintheresponsetoQuestion9.4oftheSAR.Apreliminarydeterminationoriginallyconcludedthattheconditionwasnotreportablebecausetherewasnocommitmentorsurveillancetotimedampertravel.ThefinaldeterminationofreportabilitywasmadewhentheresultsofthecalculationwereprovidedandprovedtobelessconservativethanthevaluereportedinresponsetoQuestion9.4oftheSAR.TheFuelHandlingAreaVentilationSystem(EIIS:VG)isoneofthesubsystemsoftheAuxiliaryBuildingVentilationSystem(EIIS:VF).Thefuelhandlingareaissharedbetweenunitsanditsventilationsystemisthereforeasharedfacilityconsistingofanexhaustsystemandasupplysystem.Thesupplyportionofthesystemconsistsoffoursupplyairhandlingunitsandassociatedductwork.Normallyallfoursupplyairhandlingunitsoperatedrawingoutsideairthroughintakelouversanddischargeitintothefuelhandlingarea.Thecombinedcapacityofthefoursupplyairhandlingunitsislessthanthatofasingleexhaustfan;thusthefuelhandlingareaisnormallymaintainedataslightlynegativepressure.Thefuelhandlingareaexhaustsystemiscomprisedoftwo30,000cfmfans,withanormalconfigurationofoneoperatingfanandoneinstandby.TheexhaustfansdrawairthroughacommoninletplenumandfilterassemblyfromacrossthesurfaceoftheSpentFuelPoolviainletgrillesarrangedalongthenorthsideofthepool.ThefansdischargetheexhaustairtotheoutsideatmosphereviatheAuxiliaryBuildingVentstack.TheFuelHandlingAreaVentilationSystemexhaustfilterassemblyiscomposedofrollmediaroughingfilters,highefficiencyparticulateairfiltersandcharcoalfilters.Thereisanormallyopenbypassdamperandnormallyclosedoutletdamperonthecharcoalfilter.UponreceiptofahighradiationsignalfromtheSpentFuelPoolarearadiationmonitor,thebypassdamperclosesandthecharcoalfilteroutletdamperopenstopermitexhaustairflowtopassthroughthecharcoalbedandfiltertheairbeforebeingexhausteduptheplantvent.Thebasicfunctionoftheairfilterassemblyistoremoveparticulatematteraswellasradioactiveelemental,iodinefromthefuelhandlingarea,afterreceiptofahighradiationsignal,bypassingexhaustairthroughHEPAandcharcoalfilterspnortodischargetotheplantvent.AssociatedwiththeFuelHandlingAreaVentilationSystemairfiltrationunit,arepneumaticallyoperatedfaceandbypassdampers,whosebasicfunctionistodirectairfloweitherthroughoraroundthecharcoaladsorbers.Therearesixnormallyopen,fail-closeddampers(twosetsofthreedampersmountedinseries)inthebypassandtwonormallyclosed,fail-opendampers(onesetoftwoparalleldampers)onthedischargesideofthecharcoaladsorber.TheFuelHandlingAreaVentilationSystemisdesignedtolimitoffsitereleasesfollowingafuelhandlingaccident.AhighradiationsignaIfromthefuelhandlingareawillcausethesystemtoshifttotheemergencyfiltrationmodeofoperation.Thesupplyfanswilltrip,thefiltrationunitcharcoaladsorberbypassdamperswillcloseandthedampersdownstreamofthecharcoaladsorberwillopen,thusdivertingexhaustthroughthecharcoalfilters.Asdiscussedabove,theresponsetimeoftheFuelHandlingAreaVentilationSystem,fortransitionfromthenormaltotheemergencyfiltrationmode,maynotbeadequatetopreventanunfilteredreleasefromaSpentFuelPoolaccident.However,,evaluationofthisconditionhasrevealedthatevenwithoutthebenefitsofcharcoaladsorption,theconsequencesofsuchanaccidentarewellwithin10CFR100limits.AsdocumentedintheSafetyEvaluationReport(SER)forUnit1AmendmentNo.124andUnit2AmendmentNo.211,datedMay19,1989,theNRCperformedanindependentanalysisoftheconseq'uencesofafuelhandlingaccidentintheAuxiliaryBuilding.Inthisanalysis,nocreditwasgivenforremovalofradioiodinebythecharcoalfilters.NRCFORM366A(6-1998)

V NRCFORM366AU.S.NUCLEARREGULATORYCOMMISSION(6-1999)LlCENSEEEVENTREPORT(LER)TEXTCONTINUATION~FACILITYNAME(1)CookNuclearPlantUnit1DOCKET(2)05000-315YEARLERNUMBER(6)SEQUENTIALREVISIONNUMBERNUMBERPAGE(3)4OF4199802901TEXT/Ifmorespaceisrequired,useadditionalcopiesof/I/RCForm368A/(17)Basedupontheanalysis,thestaffconcludedthatthesiteboundarythyroiddose,withoutcreditforcharcoalfiltrationorcontainment,meetstheintentofStandardReviewPlan(SRP)section15.7.4,"RadiologicalConsequencesofFuelHandlingAccidents,"acceptancecriteriaof"wellwithin"the10CFR100exposureguidelinevalues.Basedupontheaboveinformation,thiseventhadminimalimpactonthehealthandsafetyofthepublic.CORRECTIVEACTIONSTheFuelHandlingAreaVentilationSystemwasdeclaredinoperablewithTechnicalSpecificationactionstatement3.9.12ineffectonApril22,1998.AradiologicalcalculationwascompletedJuly3,1999,whichaddressesafuelhandlingaccidentoutsidecontainmentwiththeexistingfuelsources,specifictothecurrentlyplannedoffload/reloadforUnits1&2.ThiscalculationdemonstratesthatevenwithoutFuelhandlingAreaexhaustfiltration,theradiationexposuretopersonnelintheControlRoomwouldbewellwithintheGDC-19limits.AlthoughthecalculationisspecifictoControlRoomdoses,conservativeassumptionsusedinthecalculationprovideadditionalassurancethatafuelhandlingaccidentwouldresultinoffsitedosesmuchlowerthan10CFR100.InaccordancewiththeguidanceofGenericLetter91-18,anoperabilityevaluationwascompletedJuly19,1999,toaddresstheidentifiedcondition.ThisevaluationconcludedthattheFuelHandlingAreaVentilationSystemisoperable,butdegraded.Ascompensatoryaction,duringtheupcomingUnit1andUnit2coreONoadandsubsequentreload,foroperationsinvolvingmovementoffuelwithinthestoragepoolorcraneoperationwithloadsoverthestoragepool,thesystemwillbeoperatedcontinuouslyintheemergencyfiltrationmode.Theappropriateoperatingandsurveillanceprocedureshavebeenrevisedtosupportthismodeofoperation.'EP:NRC:1260GH,EnforcementActions98-150,98-151,98-152and98-186ReplytoNoticeOfViolationOctober13,1998",datedMarch19,1999,respondedtoidentifiedprogrammaticweaknessesintheplantDesignandLicensingBasis.AspartoftheRestarteffort,SystemandProgrammaticassessmentsintheExpandedSystemReadinessReviewsandLicensingBasisReviewsarereestablishinganddocumentingtheplant'sDesignandLicensingBasis.TheradiologicalanalysisfortheSpentFuelHandlingAccidentsintheAuxiliaryBuildingisbeingredoneandisscheduledtobecompletedbyAugust30,1999.SIMILAREVENTS315/99-013-00315/99-018-00315/99-012-00315/99-011-00315/99-010-00NRCFORM366A(6-1998)