ML17177A576

LER 17-003-00 for Browns Ferry, Unit 1, Regarding Unanalyzed Condition for Tornado Missiles Striking the Emergency Diesel Generator Fuel Oil Vent Lines

ML17177A576
Person / Time
Site:
Issue date:	06/26/2017
From:	Bono S M Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 17-003-00
Download: ML17177A576 (8)

Text

TennesseeValleyAuthority,PostOfficeBox2000,Decatur,Alabama35609-2000June26,2017ATTN:DocumentControlDeskU.S.NuclearRegulatoryCommissionWashington,D.C.20555-000110CFR50.73BrownsFerryNuclearPlant,Units1,2,and3RenewedFacilityOperatingLicenseNos.DPR-33,DPR-52,andDPR-68NRCDocketNos.50-259,50-260,and50-296

Subject:

LicenseeEventReport50-259/2017-003-00TheenclosedLicenseeEventReport(LER)providesdetailsofanunanalyzedconditionfortornadomissilesstrikingtheEmergencyDieselGeneratorFuelOilVentLines.TheTennesseeValleyAuthority(TVA)issubmittingthisreportinaccordancewithTitle10oftheCodeofFederalRegulations(CFR)10CFR50.73(a)(2)(ii)(B),asanyeventorconditionthatresultedinthenuclearpowerplantbeinginanunanalyzedconditionthatsignificantlydegradedplantsafety;and10CFR50.73(a)(2)(v)(A)I(B)/(D),asanyeventorconditionthatcouldhavepreventedthefulfillmentofthesafetyfunctionofstructuresorsystemsthatareneededtoshutdownthereactorandmaintainitinasafeshutdowncondition,removeresidualheat,ormitigatetheconsequencesofanaccident.FurtherevaluationisunderwaytodetermineiftheBrownsFerryNuclearPlantissusceptibletoadditionaltornadomissileeffects.Atthistime,WAanticipatestheneedtosupplementthisLERwiththeresultsofthatevaluation.Therearenonewregulatorycommitmentscontainedinthisletter.Shouldyouhaveanyquestionsconcerningthissubmittal,pleasecontactJ.L.Paul,NuclearSiteLicensingManager,at(256)729-2636.Respectfully,S.M.BonoSiteVicePresident

Enclosure:

LicenseeEventReport50-259/2017-003-00-UnanalyzedConditionforTornadoMissilesStrikingtheEmergencyDieselGeneratorFuelOilVentLines U.S.NuclearRegulatoryCommissionPage2June26,2017cc(wiEnclosure):NRCRegionalAdministrator-RegionIINRCSeniorResidentInspector-BrownsFerryNuclearPlant ENCLOSUREBrownsFerryNuclearPlantUnit1,2,and3LicenseeEventReport50-259/2017-003-00UnanalyzedConditionforTornadoMissilesStrikingtheEmergencyDieselGeneratorFuelOilVentLinesSeeEnclosed NRCFORM366U.S.NUCLEARREGULATORYCOMMISSIONAPPROVEDBY0MB:NO.3150.0104EXPIRES:03/3112020(04-2017)Estimatedburdenperresponsetocomplywiththismandatorycollectionrequest:80hours.,.'."Reportedlessonslearnedareincorporatedintothelicensingprocessandfedbacktoindustry.SendcommentsregardingburdenestimatetotheInformationServicesBranch(1-2F43),U.S.NuclearRegulatoryCommission,Washington,DC20555-0001,orbye-mailtoInfocollects.Resource@nrc.gov,andtotheDeskOfficer,OfficeofInformationandRegulatoryAffairs,NEOB-10202,(3150-0104),OffceofManagementandBudget,Washington,DC20503.Ifameansusedtoimposeaninformationcollectiondoesnotdisplayacurrentlyvalid0MBcontrolnumber,theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformationcollection.1.FACILITYNAME2.DOCKETNUMBER3.PAGEBrownsFerryNuclearPlant,Unit1050002591OF54.TITLEUnanalyzedConditionforTornadoMissilesStrikingtheEmergencyDieselGeneratorFuelOilVentLines5.EVENTDATE6.LERNUMBER7.REPORTDATE8.OTHERFACILITIESINVOLVEDSEQUENTIALFACILITYNAMEDOCKETNUMBERMONTHDAYYEARYEARNUMBERMONTHDAYYEARBrownsFerryNuclear,Unit205000260042520172017-003-0006262017FACILITYNAMEDOCKETNUMBERBrownsFerryNuclear,Unit305000296_________________9.OPERATINGMODE_________________________________11.THISREPORTISSUBM11EDPURSUANTTOTHEREQUIREMENTSOF10CFR:(Checkallthatapply)El20.2201(b)020.2203(a)(3)(i)05073(a)(2)(ii)(A)050.73(a)(2)(viii)(A)1020.2201(d)020.2203(a)(3)(ii)50.73(a)(2)(ii)(B)050.73(a)(2)(viii)(B)o20.2203(a)(1)El20.2203(a)(4)El50.73(a)(2)(iii)050.73(a)(2)(ix)(A)o20.2203(a)(2)(i)050.36(c)(1)(i)(A)050.73(a)(2)(iv)(A)El50.73(a)(2)(x)____________________10.POWERLEVEL020.2203(a)(2)(ii)El50.36(c)(1)(ii)(A)50.73(a)(2)(v)(A)073.71(a)(4)o202203(a)(2)(iii)El50.36(c)(2)50.73(a)(2)(v)(B)El73.71(a)(5)100020.2203(a)(2)(iv)050.46(a)(3)(ii)El50.73(a)(2)(v)(C)El73.77(a)(1)El202203(a)(2)(v)El50.73(a)(2)(i)(A)Z50.73(a)(2)(v)(D)073.77(a)(2)(i)El202203(a)(2)(vi)El50.73(a)(2)(i)(B)El50.73(a)(2)(vii)073.77(a)(2)(ii)050.73(a)(2)(i)(C)0OTHERSpecifyinAbstractbeloworinNRCForm366A12.LICENSEECONTACTFORTHISLERLICENSEECONTACTTELEPHONENUMBER(IncludeAreaCode)RyanCoons,LicensingEngineer56-729-207013.COMPLETEONEUNEFOREACHCOMPONENTFJLUREDESCRIBEDINTHISREPORTCAUSESYSTEMCOMPONENTFACTURERREPORTABLECAUSESYSTEMCOMPONENTFACTURERREPORTABLEN/AN/AN/AN/AN/AN/AN/AN/AN/AN/A14.SUPPLEMENTALREPORTEXPECTED15.EXPECTEDMONTHDAYYEARYES(Ifyes,complete15.EXPECTEDSUBMISSIONDATE)LINOSUBMISSION08252017BSTRACT(Limitto1400spaces,i.e.,approximately15single-spacedtypewrittenfines)InaccordancewithNRCRegulatoryIssueSummary(RIS)2015-06,TornadoMissileProtection,adesignandlicensingbasisreviewwasperformedtoevaluatetheeffectsofexposingsafetyrelatedfeaturestotornadowindloads,depressurizationloads,andstrikesfromtornadogeneratedmissiles.OnApril25,2017,itwasdiscoveredthatatornadomissilestrikecouldpotentiallydamagetheexposedandunprotectedportionoftheD,3A,3B,3C,and3DEmergencyDieselGenerator(EDG)fueloilventlines.Thiscouldpotentiallyfullycrimptheventline,anddisablethetank'svacuumpreventionfeature.Developingavacuuminthefueloilsystemwouldlimitthefueloilpump'sabilitytotransferfueloilfromthe7daytanktothedaytank,restrictingoreliminatingthefueloilflowtotheaffectedEDG,whichwouldpreventtheEDGfromfunctioning.Thedevelopmentofavacuummayalsodamagethe7daytank.Thisconditionisanoriginalplantdesignlegacyissue.Duetothehistoricalnatureofthisvulnerability,aspecificcausewasnotidentified.Ihecompensatorymeasuresimplementedprovidealternatefueltankventingassoonasatornadowarninghasbeendeclared.Thisisimplementedbyremovingasamplingplugfromeachof7dayfueltankmanholecoversinsidetheD,3A,3B,3C,and3DEDGrooms.NRCFORM366(04-2017)

NRCFORM366AU.S.NUCLEARREGULATORYCOMMISSIONAPPROVEDBY0MB:NO.3150-0104EXPIRES:3/3112020(04-2017)Estimatedburdenperresponsetocomplywiththismandatorycollectionrequest:80hours.Reportedlessonslearnedareincorporatedintothelicensingprocessandfedbacktoindustry.SendLICENSEEEVENTREPORT(LER)commentsregardingburdenestimatetotheInformationServicesBranch(T-2F43),U.S.NuclearCONTINUATIONSHEETRegulatoryCommission,Washington,DC20555-0001,orbye-mailtolnfocollects.Resoercenrc.gov,andtotheDeskOfficer,OfficeofInformationandRegulatoryAffairs,NEOB-10202,(3150-0104),OfficeofManagementandBedget,Washington,DC20503.Ifameansusedtoimposeaninformationcollectiondoesnotdisplayacurrentlyvalid0MBcontrolnumber,theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformationcollection.1.FACILITYNAME2.DOCKETNUMBER3.LERNUMBERYEARSEQUENTIALREVNUMBERINO.BrownsFerryNuclearPlant,Unit105000-2592017-003-00NARRATIVEI.PlantOperatingConditionsBeforetheEventAtthetimeofdiscovery,BrownsFerryNuclearPlant(BFN),Units1,2,and3,wereinMode1at100percentpower.ILDescriptionofEventA.EventSummaryInaccordancewithNRCRegulatoryIssueSummary(RIS)2015-06,TornadoMissileProtection(TMP),adesignandlicensingbasisreviewwasperformedtoevaluatetheeffectsofexposingsafetyrelatedfeaturestotornadowindloads,depressurizationloads,andstrikesfromtornadogeneratedmissiles.OnApril25,2017,itwasdiscoveredduringthisevaluationthatdamagetotheexposedandunprotectedportionoftheD,3A,3B,3C,and3DEmergencyDieselGenerator(EDG)[DC]fueloilventlines[VLR]byatornadomissilestrikehasthepotentialtofullycrimptheventline,whichwouldrenderthevacuumpreventionfeatureineffective.Developingavacuuminthefueloilsystem[DE]wouldlimittheabilityofthefueloilpumps[P]totransferfueloilfromthe7daytank[TK]tothedaytank.ThiswouldrestrictoreliminatetheflowoffueloiltotheaffectedEDG,whichwouldpreventtheEDGfromfunctioning.Adevelopmentofavacuummayalsodamagethe7daytank.B.Statusofstructures,components,orsystemsthatwereinoperableatthestartoftheeventandthatcontributedtotheeventTherewerenostructures,systems,orcomponentswhoseinoperabilitycontributedtothiscondition.C.DatesandapproximatetimesofoccurrencesDates&ApproximateTimesOccurrenceApril25,2017,TheD,3A,3B,3C,and3DEDGsweredeclaredat1630CDTinoperablefollowinganengineeringevaluationofTMP,whichfoundthattheEDG7daytankventpipingissubjecttopotentialdamage.April25,2017,InaccordancewithNRCEnforcementGuideat1631CDTMemorandum(EGM)15-002,Revision1,EnforcementDiscretionforTornado-GeneratedMissileProtectionNon-Compliance,initialcompensatorymeasureswereimplementedwhichprovideadditionalprotectionandlessentornadomissileeffects.NRCFORM366A(04-2017)Page2of5 NRCFORM366AU.S.NUCLEARREGULATORYCOMMISSIONAPPROVEDBY0MB:NO.3150-0104EXPIRES:313112020(04-2017)Estimatedburdenperresponsetocomplywiththismandatorycollectionrequest:80hours.Reportedlessonslearnedareincorporatedintothelicensingprocessandfedbacktoindustry.SendLICENSEEEVENTREPORT(LER)commentsregardingburdenestimatetotheInformationServicesBranch(T-2F43),U.S.NuclearCONTINUATIONSHEETRegulatoryCommission,Washington,DC20555-0001,orbye-mailtolnfocollects.Resource@nrc.gov,andtotheDeskOfficer,OfficeofInformationandRegulatoryAffairs,NEOB-10202,(3150-0104),OfficeofManagementandBudget,Washington,DC20503.Ifameansusedtoimposeaninformationcollectiondoesnotdisplayacurrentlyvalid0MBcontrolnumber,theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformationcollection.1.FACILITYNAMEI2.DOCKETNUMBERI3.LERNUNIBERYEARSEQUENTIALREVNUMBERNO.BrownsFerryNuclearPlant,Unit105000-2592017-003-00Dates&ApproximateTimesOccurrenceApril25,2017,TheD,3A,3B,3C,and3DEDGsweredeclaredat1647CDTOperableatthistime.April25,2017,TheNRCwasnotifiedoftheunanalyzedconditionthatat1653CDTsignificantlydegradedplantsafety.D.ManufacturerandmodelnumberofeachcomponentthatfailedduringtheeventThisconditiondidnotinvolveanyequipmentfailure.E.OthersystemsorsecondaryfunctionsaffectedNoothersystemsorsecondaryfunctionswereaffectedbythiscondition.F.MethodofdiscoveryofeachcomponentorsystemfailureorproceduralerrorThiseventdidnotinvolvetheactualfailureofplantequipment.However,anunanticipatedpotentialforfailurewasdiscoveredonApril25,2017,aspartofadesignandlicensingbasisreviewtoevaluatetheeffectsoftornadosandtornadomissilesonsafetyrelatedfeatures,inaccordancewithRIS2015-06.G.Thefailuremode,mechanism,andeffectofeachfailedcomponentThisconditiondidnotinvolvetheactualfailureofplantequipment.H.OperatoractionsTherewerenooperatoractionsassociatedwiththiscondition.I.AutomaticallyandmanuallyinitiatedsafetysystemresponsesTherewerenoautomaticormanualsafetysystemresponsesassociatedwiththiscondition.Ill.CauseoftheeventA.CauseofeachcomponentorsystemfailureorpersonnelerrorThisconditionisanoriginalplantdesignlegacyissue.Duetothehistoricalnatureofthisvulnerability,aspecificcausewasnotidentified.B.Cause(s)andcircumstancesforeachhumanperlormancerelatedrootcauseTherewerenohumanperformancerelatedrootcausesforthiscondition.NRCFORM366A(04-2017)Page3of5 NRCFORM366AU.S.NUCLEARREGULATORYCOMMISSIONAPPROVEDBY0MB:NO.3150-0104EXPIRES:3/31/2020(04-2017)Estimatedburdenperresponsetocomplywiththismandatorycollectionrequest:80hours.Reportedlessonslearnedareincorporatedintothelicensingprocessandfedbacktoindustry.SendLICENSEEEVENTREPORT(LER)commentsregardingburdenestimatetotheInformationServicesBranch(T-2F43),U.S.NuclearCONTINUATIONSHEETRegulatoryCommission,Washington,DC20555-0001,orbye-mailtolnfocollects.Resourcenrc.gov,andtotheDeskOfficer,OfficeofInformationandRegulatoryAffairs,NEOB-10202,(3150-0104),OfficeofManagementandBudget,Washington,DC20503.Ifameansusedtoimposeaninformationcollectiondoesnotdisplayacurrentlyvalid0MBcontrolnumber,theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformationcollection.1.FACILITYNAMEI2.DOCKETNUMBERI3.LERNUMBERYEARSEQUENTIALREVINUMBERINO.BrownsFerryNuclearPlant,Unit105000-2592017-003-00IV.AnalysisoftheeventTheTennesseeValleyAuthority(TVA)issubmittingthisreportinaccordancewithTitle10oftheCodeofFederalRegulations(CFR)50.73(a)(2)(ii)(B),asanyeventorconditionthatresultedinthenuclearpowerplantbeinginanunanalyzedconditionthatsignificantlydegradedplantsafety;and10CFR50.73(a)(2)(v)(A)/(B)/(D),asanyeventorconditionthatcouldhavepreventedthefulfillmentofthesafetyfunctionofstructuresorsystemsthatareneededtoshutdownthereactorandmaintainitinasafeshutdowncondition,removeresidualheat,ormitigatetheconsequencesofanaccident.TheconditionwasdiscoveredonApril25,2017,at1630CDT,whenanengineeringevaluationofTMPdeterminedthatthe7daytankventpipingissubjecttopotentialdamagefortheD,3A,3B,3C,and3DEDGsrenderingtheEDGsinoperableforpotentialtornadomissileprotection.AnactualtornadomissileeventcouldhavecausedasafetysystemfunctionalfailureduetotheinoperabilityofmultipleEDGs.However,compensatorymeasureswereestablishedtoprovideadditionalprotectionforalleviatingtornadomissileeffects,inaccordancewithEGM15-002,Revision1.TheseinitialcompensatorymeasuresallowedtheaffectedEDGstobeconsideredOperablebutnonconforming.FurtherevaluationisunderwaytodetermineifBFNissusceptibletoadditionaltornadomissileeffects.Atthistime,WAanticipatestheneedtosupplementthisLERwiththeresultsofthatevaluation.V.AssessmentofSafetyConsequencesTheexposedportionofthefueloilventlinesfortheD,3A,3B,3Cand3DEDGsarenotprotectedfromatornadogeneratedmissilestrike.Anexposedportionofafueloilventlinecouldexperiencecrimpingdamagesuchthatitcannotperformitsfunctiontopreventthedevelopmentofavacuuminthefueloilsystem.Thedevelopmentofavacuuminthefueloilsystemwouldrenderthefueloiltransfersystemfromthe7daytanktothedaytankineffective.TheaffectedEDG(s)wouldbeunabletofunctionduetolackoffueloil.TopreventtornadomissileinducedEDGinoperability,BFNOperationspersonnelarenowprocedurallyrequiredtoopenanalternateventilationpathontheEDG7dayfueltanksfollowingthedeclarationofatornadowarning.ThisconditionhadnoactualsafetyconsequencesimpactingplantorpublicsafetybecauseBFNdidnotexperienceanactualtornadomissileevent;however,thecompensatoryactionsthathavebeenimplementedintheSevereWeatherprocedurewillmanagethiscondition'srisktothehealthandsafetyofthepublic.A.AvailabilityofsystemsorcomponentsthatcouldhaveperformedthesamefunctionasthecomponentsandsystemsthatfailedduringtheeventThisconditiondidnotresultinanyactualsystemorcomponentfailures.NRCFORM366A(04-2017)Page4of5 NRCFORM366AU.S.NUCLEARREGULATORYCOMMISSIONAPPROVEDBY0MB:NO.3150-0104EXPIRES:3/3112020(04-2017)Estimatedburdenperresponsetocomplywiththismandatorycollectionrequest:80hours.Reportedlessonslearnedareincorporatedintothelicensingprocessandfedbacktoindustry.SendLICENSEEEVENTREPORT(LER)commentsregardingburdenestimatetotheInformationServicesBranch(T-2F43),U.S.NuclearCONTINUATIONSHEETRegulatoryCommission,Washington,DC20555-0001,orbye-mailtolnfocollects.Resourcenrc.gov,andtotheDeskOfficer,OfficeofInformationandRegulatoryAffairs,NEOB-10202,(3150-0104),OfficeofManagementandBudget,Washington,DC20503.Ifameansusedtoimposeaninformationcollectiondoesnotdisplayacurrentlyvalid0MBcontrolnumber,theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformationcollection.1.FACILITYNAMEI2.DOCKETNUMBERI3.LERNUMBERYEARISEQUENTIALREVNUMBERINO.BrownsFerryNuclearPlant,Unit105000-2592017-003-00B.Foreventsthatoccurredwhenthereactorwasshutdown,availabilityofsystemsorcomponentsneededtoshutdownthereactorandmaintainsafeshutdownconditions,removeresidualheat,controlthereleaseofradioactivematerial,ormitigatetheconsequencesofanaccidentThisconditiondidnotoccurduringashutdown.C.Forfailurethatrenderedatrainofasafetysysteminoperable,estimateoftheelapsedtimefromdiscoveryofthefailureuntilthetrainwasreturnedtoserviceThisconditionisanoriginalplantdesignlegacyissue.Duetothehistoricalnatureofthisvulnerability,aspecificcausewasnotidentified.Initialcompensatorymeasurestorestoreoperabilitywereimplementedwithin17minutesofdiscoveringthecondition.VI.CorrectiveActionsCorrectiveActionsarebeingmanagedbyTVA'scorrectiveactionprogramunderConditionReport(CR)1288222.A.ImmediateCorrectiveActionsAnoperatorworkaroundwasimplementedtoprovideanalternatefueltankventingassoonaspossiblefollowingatornadoevent.B.CorrectiveActionstoPreventRecurrenceortoreducetheprobabilityofsimilareventsoccurringinthefutureThecomprehensivecompensatorymeasuresincludedrevisingtheSevereWeatherproceduretoincluderemovingasamplingplugoneachoftheEDG7dayfueloiltankstoprovideanalternateventilationpathwhenatornadowarninghasbeendeclared.Thesecomprehensivecompensatorymeasureswillremaininplaceuntilthevulnerabilityispermanentlyresolved.VII.PreviousSimilarEventsattheSameSiteAsearchoftheBFNCorrectiveActionProgramidentifiednosimilarconditionsthathaveoccurredatBFN.VIII.AdditionalInformationThereisnoadditionalinformation.IX.CommitmentsTherearenonewcommitments.NRCFORM366A(04-2017)Page5of5