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
Person / Time
Site:
Issue date:	08/04/1999
From:	BERRY L R INDIANA MICHIGAN POWER CO.
To:
Shared Package
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
Download: ML17326A077 (6)

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NRCFORM366U.S.NUCLEARREGUYCOMMISSION (6-1996)LICENSEEEVENTREPORT(LER){Seereverseforrequirednumberofdigits/characters foreachblock)APPROYOMBNO.3150-0104 EXPIRES06/30/2001 Estimated burdenperresponsetocomplywiththismandatory information collection request:50hrs.Reportedlessonslearnedareincorporated intothelicensing processandfedbacktoindustry.

Forwardcommentsregarding burdenestimatetotheRecordsManagement Branch(TAF33).U.S.NuclearRegulatory Commission.

Washington.

DC205550001, andtothePaperwork Reduction Project(3t500104).

05ceofManagement andBudget,Washington.

DC20503.Ifaninformation collection doesnotdisplayacurrently validOMBcontrolnumber.theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformation collection.

FACILITYNAME(1)CookNuclearPlantUnit1DOCKETNUMBER(2)05000-315 PAOE(3)1OF4TITlEI4IFuelHandlingAreaVentilation SystemInoperable DuetoOriginalDesignDeficiency EVENTDATE{5)LERNUMBER{6)REPORTDATE{7)OTHERFACILITIES INVOLVED{6)MONTHDAYYEARYEAR1998SEQUENTIAL NUMBERREVISIONNUMBERMONTHDAY199FACILITYNAMECookNuclearPlantUnit2FACILllYNAMEDOCKETNUMBER05000-316 DOCKETIIUMBEROPERATING MODE(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,Compliance Engineer{12)TELEPHONE NUMBERIIndudeAreaCode)(616)465-5901x1623COMPLETEONELINEFOREACHCOMPONENT FAILUREDESCRIBEDINTHISREPORT{13)CAUSESYSTEMCOMPONENT MANUFACTURER REPORTABLE "ToEPIXCAUSESYSTEMCOMPONENT MANUFACTURER REPORTABLE ToEPIXSUPPLEMENTAL REPORTEXPECTED14YES{Ifyes,completeEXPECTEDSUBMISSION DATE).XNOEXPECTEDMONTHDAYYEARABSTRACT(Limitto1400spaces,i.o.,approximately 15single-spaced typewritten lines)(16)OnApril22,1998,duringpreparation oftheRadiation Monitoring SystemDesignBasisDocument(DBD),itwasidentified thattheresponsetimeoftheFuelHandlingAreaVentilation System,fortransition fromthenormaltotheemergency filtration mode,maynotbeadequatetopreventanunfiltered releasefromarefueling accidentoutsidecontainment.

Currentoff-sitedosecalculations assumefiltration foranaccidentintheAuxiliary Building.

Thisconcernwasidentified bycontractor personnel reviewing astatement madeinresponsetoNRCQuestion9.4fortheSAR.Thisquestionrequested designdetailstodemonstrate thattheresponsetimeofthecharcoaladsorberbypassdamperwasadequatetopreventapotential "puffrelease"totheenvironment afterahighradiation signalwasreceived.

Afterresearching existingdocumentation andperforming ascopingcalculation, itwasdetermined thattheresponsetimeofthebypassdamperdescribed inreplytotheSARquestionwasinadequate topreventanunfiltered release.Areleasefromarefueling accident(droppedfuelbundle)intheSpentFuelPoolwascalculated toreachthebypassdamperbeforeinitiation ofcharcoalfiltration.

Consequently, sincetheFuelHandlingAreaVentilation Systemhadbeendetermined tobeincapable ofperforming itsspecified

function, itwasdeclaredinoperable.

Sincethiscondition waspreviously unknown,nocompensatory actionshadbeenhistorically taken.TheFuelHandlingAreaVentilation Systemiscommontobothunits.OnMay27,1998,thiscondition wasdetermined tobereportable pursuanttotherequirements of10CFR50.73(a)(2)(i)(B),

asoperation orcondition prohibited bytheplant'sTechnical Specifications.

Therootcauseofthiscondition isadesigndeficiency, whichhasbeenpresentsinceplantconstruction.

Evaluation ofthiscondition hasdetermined thatevenwithoutthecharcoalbedinservice,theconsequences ofapostulated fuelhandlingaccidentarewellwithin10CFR100limits.Baseduponthisinformation, thiseventhadminimalimpactonthehealthandsafetyofthepublic.9908iOOi40 990804PP"ADCICK0500/13i5

NRCFORM366AU.S.NUCLEARADULATORY COMMISSION 16-1998)LICENSEEEVENTREPORT(LER)TEXTCONTINUATION FACIUTYNAMEI1)DocKETI2)LERNUMBERI6)PAGEI3)CookNuclearPlantUnit105000-315 YEARSEQUENTIAL NUMBER2OF4NUMBER199802901TEXT/Ifmorespacoisreriuired, usoadditional copiesofNRCRearm366AII17)Conditions PriortoEventUnit1Mode5,ColdShutdownUnit2Mode5,ColdShutdownDescritionoftheEventOnApril22,1998,duringpreparation oftheRadiation Monitoring SystemDesignBasisDocument(DBD),itwasidentified thattheresponsetimeoftheFuelHandlingAreaVentilation System(EIIS:VG),

fortransition fromthenormaltotheemergency filtration mode,maynotbeadequatetopreventanunfiltered releasefromarefueling accidentoutsidecontainment.

Currentoff-sitedosecalculations assumefiltration intheAuxiliary Building.

Thisconcernwasidentified bycontractor personnel reviewing astatement madeinresponsetoNRCQuestion9.4(Amendment 20,March,1972)fortheSAR.Thisquestionrequested designdetailstodemonstrate thattheresponsetimeofthecharcoaladsorberbypassdamper(EIIS:VG/CDMP) wasadequatetopreventapotential "puffrelease"totheenvironment afterahighradiation signalwasreceived.

TheresponsetoSARQuestion9.4wasasfollows:"Exhausted airfromthespentfuelpitwillreachthecharcoalfilterbypassdampersin4seconds(basedontheshortestpath).Thetimeelapsedfromreceiving ahighradiation signalattheradiation monitortothefullshutpositionofthecarbonfilterbypassdamperislessthan3seconds.Theinvestigation revealedthatthereislittle'existing documentation onthisoriginaldesignfeature.Afteranextensive search,itwasdetermined thatnoinformation couldbelocatedwhichsupported, orprovidedabasisfor,thestatement intheSARQuestion9.4response.

Ascopingcalculation wasperformed forthetimeexpectedforareleasefromtheSpentFuelPooltoreachthedampers.Thiscalculation indicated thattheairtransittimewasfessthan1second,whichislessthanthe3secondresponsetimeforthecombination ofradiation monitoractuation andbypassdampermovement.

Sincenotestdatacouldbelocatedtodemonstrate thatthetransition totheemergency filtration modewasrapidenoughtopreventarelease,thesystemwasconsidered tobeinoperable.

TheFuelHandlingAreaVentilation Systemiscommontobothunits.CauseofEventThiscondition isattributed toadeficiency intheoriginaldesign.Asnodocumentation oftheoriginalpostulated airtransport timeversustimefordamperoperation couldbelocated,itwasnotpossibletoreconstruct thedesignbasisforradiation monitoractuation oftheemergency filtration modeforthesystem'.AnalsisofEventOnMay27,1998,withbothUnit1andUnit2inMode5,itwasconcluded thatthiseventwasreportable under10CFR50.73(a)(2)(i)(B),

asanoperation orcondition prohibited bytheplantTechnical Specifications.

Thisconclusion wasreachedbecausetheFuelHandlingAreaVentilation systemwasinoperable fromtimeofplantstartupandhasremainedinoperable.

Technical Specification 3.9.12,.which prohibits fuelmovementwiththesysteminoperable, wasviolatedwheneverfuelwasmovedwithoutthecharcoalfilterbeinginservice.Theoriginaldelayindetermining thereportability ofthiscondition wasprimarily duetothescarcityofinformation pertaining tothisdesignfeature.NRCFORM366AI6-1996)

NRCFORM366AU.S.NUCLEARREGULATORY COMMISSION (6.1999)LlCENSEEEVENTREPORT(LER)TEXTCONTINUATION FACILITYNAME(1)CookNuclearPlantUnit1DOCKET(2)05000-315 YEARLERNUMBER(6)PAGE(3)SEQUENTIAL REVISION3QF4NUMBERNUMBER199802901TEXTiifmorespaceisrequired, useadditiorIal copiesofIVRCForm366AJ(17)Nodocumentation or.calculation couldbefoundtosupporttheresponsetimeandairtransittimesreportedintheresponsetoQuestion9.4oftheSAR.Apreliminary determination originally concluded thatthecondition wasnotreportable becausetherewasnocommitment orsurveillance totimedampertravel.Thefinaldetermination ofreportability wasmadewhentheresultsofthecalculation wereprovidedandprovedtobelessconservative thanthevaluereportedinresponsetoQuestion9.4oftheSAR.TheFuelHandlingAreaVentilation System(EIIS:VG) isoneofthesubsystems oftheAuxiliary BuildingVentilation System(EIIS:VF).

Thefuelhandlingareaissharedbetweenunitsanditsventilation systemistherefore asharedfacilityconsisting ofanexhaustsystemandasupplysystem.Thesupplyportionofthesystemconsistsoffoursupplyairhandlingunitsandassociated ductwork.

Normallyallfoursupplyairhandlingunitsoperatedrawingoutsideairthroughintakelouversanddischarge itintothefuelhandlingarea.Thecombinedcapacityofthefoursupplyairhandlingunitsislessthanthatofasingleexhaustfan;thusthefuelhandlingareaisnormallymaintained ataslightlynegativepressure.

Thefuelhandlingareaexhaustsystemiscomprised oftwo30,000cfmfans,withanormalconfiguration ofoneoperating fanandoneinstandby.TheexhaustfansdrawairthroughacommoninletplenumandfilterassemblyfromacrossthesurfaceoftheSpentFuelPoolviainletgrillesarrangedalongthenorthsideofthepool.Thefansdischarge theexhaustairtotheoutsideatmosphere viatheAuxiliary BuildingVentstack.TheFuelHandlingAreaVentilation Systemexhaustfilterassemblyiscomposedofrollmediaroughingfilters,highefficiency particulate airfiltersandcharcoalfilters.Thereisanormallyopenbypassdamperandnormallyclosedoutletdamperonthecharcoalfilter.Uponreceiptofahighradiation signalfromtheSpentFuelPoolarearadiation monitor,thebypassdamperclosesandthecharcoalfilteroutletdamperopenstopermitexhaustairflowtopassthroughthecharcoalbedandfiltertheairbeforebeingexhausted uptheplantvent.Thebasicfunctionoftheairfilterassemblyistoremoveparticulate matteraswellasradioactive elemental, iodinefromthefuelhandlingarea,afterreceiptofahighradiation signal,bypassingexhaustairthroughHEPAandcharcoalfilterspnortodischarge totheplantvent.Associated withtheFuelHandlingAreaVentilation Systemairfiltration unit,arepneumatically operatedfaceandbypassdampers,whosebasicfunctionistodirectairfloweitherthroughoraroundthecharcoaladsorbers.

Therearesixnormallyopen,fail-closed dampers(twosetsofthreedampersmountedinseries)inthebypassandtwonormallyclosed,fail-open dampers(onesetoftwoparalleldampers)onthedischarge sideofthecharcoaladsorber.

TheFuelHandlingAreaVentilation Systemisdesignedtolimitoffsitereleasesfollowing afuelhandlingaccident.

Ahighradiation signaIfromthefuelhandlingareawillcausethesystemtoshifttotheemergency filtration modeofoperation.

Thesupplyfanswilltrip,thefiltration unitcharcoaladsorberbypassdamperswillcloseandthedampersdownstream ofthecharcoaladsorberwillopen,thusdiverting exhaustthroughthecharcoalfilters.Asdiscussed above,theresponsetimeoftheFuelHandlingAreaVentilation System,fortransition fromthenormaltotheemergency filtration mode,maynotbeadequatetopreventanunfiltered releasefromaSpentFuelPoolaccident.

However,,evaluation ofthiscondition hasrevealedthatevenwithoutthebenefitsofcharcoaladsorption, theconsequences ofsuchanaccidentarewellwithin10CFR100limits.Asdocumented intheSafetyEvaluation Report(SER)forUnit1Amendment No.124andUnit2Amendment No.211,datedMay19,1989,theNRCperformed anindependent analysisoftheconseq'uences ofafuelhandlingaccidentintheAuxiliary Building.

Inthisanalysis, nocreditwasgivenforremovalofradioiodine bythecharcoalfilters.NRCFORM366A(6-1998)

V NRCFORM366AU.S.NUCLEARREGULATORY COMMISSION (6-1999)LlCENSEEEVENTREPORT(LER)TEXTCONTINUATION

~FACILITYNAME(1)CookNuclearPlantUnit1DOCKET(2)05000-315 YEARLERNUMBER(6)SEQUENTIAL REVISIONNUMBERNUMBERPAGE(3)4OF4199802901TEXT/Ifmorespaceisrequired, useadditional copiesof/I/RCForm368A/(17)Basedupontheanalysis, thestaffconcluded thatthesiteboundarythyroiddose,withoutcreditforcharcoalfiltration orcontainment, meetstheintentofStandardReviewPlan(SRP)section15.7.4,"Radiological Consequences ofFuelHandlingAccidents,"

acceptance criteriaof"wellwithin"the10CFR100exposureguideline values.Basedupontheaboveinformation, thiseventhadminimalimpactonthehealthandsafetyofthepublic.CORRECTIVE ACTIONSTheFuelHandlingAreaVentilation Systemwasdeclaredinoperable withTechnical Specification actionstatement 3.9.12ineffectonApril22,1998.Aradiological calculation wascompleted July3,1999,whichaddresses afuelhandlingaccidentoutsidecontainment withtheexistingfuelsources,specifictothecurrently plannedoffload/reload forUnits1&2.Thiscalculation demonstrates thatevenwithoutFuelhandlingAreaexhaustfiltration, theradiation exposuretopersonnel intheControlRoomwouldbewellwithintheGDC-19limits.Althoughthecalculation isspecifictoControlRoomdoses,conservative assumptions usedinthecalculation provideadditional assurance thatafuelhandlingaccidentwouldresultinoffsitedosesmuchlowerthan10CFR100.Inaccordance withtheguidanceofGenericLetter91-18,anoperability evaluation wascompleted July19,1999,toaddresstheidentified condition.

Thisevaluation concluded thattheFuelHandlingAreaVentilation Systemisoperable, butdegraded.

Ascompensatory action,duringtheupcomingUnit1andUnit2coreONoadandsubsequent reload,foroperations involving movementoffuelwithinthestoragepoolorcraneoperation withloadsoverthestoragepool,thesystemwillbeoperatedcontinuously intheemergency filtration mode.Theappropriate operating andsurveillance procedures havebeenrevisedtosupportthismodeofoperation.'EP:NRC:1260GH, Enforcement Actions98-150,98-151,98-152and98-186ReplytoNoticeOfViolation October13,1998",datedMarch19,1999,responded toidentified programmatic weaknesses intheplantDesignandLicensing Basis.AspartoftheRestarteffort,SystemandProgrammatic assessments intheExpandedSystemReadiness ReviewsandLicensing BasisReviewsarereestablishing anddocumenting theplant'sDesignandLicensing Basis.Theradiological analysisfortheSpentFuelHandlingAccidents intheAuxiliary Buildingisbeingredoneandisscheduled tobecompleted byAugust30,1999.SIMILAREVENTS315/99-013-00 315/99-018-00 315/99-012-00 315/99-011-00 315/99-010-00 NRCFORM366A(6-1998)