ML17150A024

LER 17-003-00 for Browns Ferry Nuclear Plant, Unit 2 Regarding Manual Reactor Scram Initiated During Startup Due to Multiple Rods Inserting

ML17150A024
Person / Time
Site:	Browns Ferry
Issue date:	05/30/2017
From:	Bono S M Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 17-003-00
Download: ML17150A024 (7)

Text

TennesseeValleyAuthority,PostOfficeBox2000,Decatur,Alabama35609-2000May30,2017ATTN:DocumentControlDeskU.S.NuclearRegulatoryCommissionWashington,D.C.20555-0001BrownsFerryNuclearPlant,Unit2RenewedFacilityOperatingLicenseNo.DPR-52NRCDocketNo.50-260

Subject:

LicenseeEventReport50-260/2017-003-0010CFR50.73TheenclosedLicenseeEventReportprovidesdetailsofamanualreactorscraminitiatedduringstartupduetomultiplerodsinserting.TheTennesseeValleyAuthorityissubmittingthisreportinaccordancewithTitle10oftheCodeofFederalRegulations50.73(a)(2)(iv)(A),anyeventorconditionthatresultedinamanualorautomaticactuationoftheReactorProtectionSystem.Therearenonewregulatorycommitmentscontainedinthisletter.Shouldyouhaveanyquestionsconcerningthissubmittal,pleasecontactM.W.Oliver,NuclearSiteLicensingManager,at(256)729-2636.ctfully,S.M.Site

Enclosure:

LicenseeEventReport50-260/2017-003-00-ManualReactorScramInitiatedDuringStartupDuetoMultipleRodsInsertingcc(w/Enclosure):NRCRegionalAdministrator-RegionIINRCSeniorResidentInspector-BrownsFerryNuclearPlant ENCLOSUREBrownsFerryNuclearPlantUnit2LicenseeEventReport50-260/2017-003-00ManualReactorScramInitiatedDuringStartupDuetoMultipleRodsInsertingSeeEnclosed NRCFORM366U.S.NUCLEARREGULATORYCOMMISSIONAPPROVEDBY0MB:NO.3150-0104EXPIRES:03/31/2020(04-2017)Estimatedburdenperresponsetocomplywiththismandatorycollectionrequest:80hours./Reportedlessonslearnedareincorporatedintothelicensingprocessandfedbacktoindustry..j.ISendcommentsregardingburdenestimatetotheInformationServicesBranch(T-2F43),U.S.NuclearRegulatoryCommission,Washington,DC20555-0001orbye-mailtoInfocollects.Resoarce@nrc.gov,andtotheDeskOfficer,OfficeofInformationandRegulatoryAffairs,NEOB-10202,(3150-0104),OfficeofManagementandBudget,Washington,DC20503.Ifameansusedtoimposeaninformationcollectiondoesnotdisplayacurrentlyvalid0MBcontrolnumber,theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformationcollection.1.FACILITYNAME2.DOCKETNUMBER3.PAGEBrownsFerryNuclearPlant,Unit2050002601OF54.TITLEManualReactorScramInitiatedDuringStartupDuetoMultipleRodsInserting5.EVENTDATE6.LERNUMBER7.REPORTDATE8.OTHERFACILITIESINVOLVEDSEt'UENTIALREVFACILITYNAMEDOCKETNUMBERMONTHDAYYEARYEARNUMBERNO.MONTHDAYYEARN/AN/A032920172017-003-0005302017FACUJTYNAMEDOCKETNUMBERaOPERA11NGMODE11.ThIsREPORTISSUBMITFEDPURSUANTTOThEREQUIREMENTSOF10CFR:(Checkallthatapply)o20.2201(b)020.2203(a)(3)(i)050.73(a)(2)(ii)(A)05O73(a)(2)(viii)(A)2020.2201(d)020.2203(a)(3)(ii)050.73(a)(2)(ii)(B)050.73(a)(2)(viii)(B)o20.2203(a)(1)El20.2203(a)(4)050.73(a)(2)(iii)050.73(a)(2)(ix)(A)____________________o20.2203(a)(2)(i)050.36(c)(1)(i)(A)50.73(a)(2)(iv)(A)050.73(a)(2)(x)10.POWERLEVEL020.2203(a)(2)(ii)050.36(c)(1)(ii)(A)050.73(a)(2)(v)(A)073.71(a)(4)o20.2203(a)(2)(iii)050.36(c)(2)050.73(a)(2)(v)(B)073.71(a)(5)000020.2203(a)(2)(iv)050.46(a)(3)(ii)El50.73(a)(2)(v)(C)073.77(a)(1)020.2203(a)(2)(v)050.73(a)(2)(i)(A)050.73(a)(2)(v)(D)073.77(a)(2)(i)020.2203(a)(2)(vi)050.73(a)(2)(i)(B)050.73(a)(2)(vU)073.77(a)(2)(ii)U50.73(a)(2)(i)(C)0OTHERSpecifyinAbstractbeloworinNRCForm366A12.LICENSEECONTACTFORTHISLERLICENSEECONTACTTELEPHONENUMBER(IncludeAreaCode)RyanCoons,LicensingEngineer56-729-207013.COMPLEFEONEUNEFOREACHCOMPONENTFAAJLURDESCRIBEDINThISREPORTCAUSESYSTEMCOMPONENTFACTURERREPORTABLECAUSESYSTEMCOMPONENTFACTURERREPORTABLEBJCAMPG080YBJC57G080Y14.SUPPLEMENTALREPORTEXPECTED15.EXPECTEDMONTHDAYYEARLIYES(Ifyes,complete15.EXPECTEDSUBMISSIONDATE)IINOSUBMSIONN/AN/AN/ABSTRACT(Limitto1400spaces,i.e.,approxImately15single-spacedtypewrittenlines)OnMarch29,2017,at1842CentralDaylightTime(CDT),duringUnit2start-up,OperationspersonnelreceivedannunciatorsforanIntermediateRangeMonitor(IRM)DownscaleandaControlRodWithdrawalBlock.OperationspersonnelnoticedthatIRM'G'wasreadingdownscaleandadjustedtherangedownonepositionwithnoimmediatereaction.At1844CDT,anupscalespikeonIRM'G'causedahalfscramonReactorProtectionSystem(RPS)'A'tripsystem.AfterverifyingthattheIRM'G'High-Hightripsignalwascleared,OperationspersonnelresetthehalfscramonRPS'A'.Animmediate,concurrenttripsignalfromIRM'F'wasthenreceivedontheRPS'B'tripsystem,resultinginmultiplerodsinsertingintothecore.WhenOperationspersonnelidentifiedmultiplerodsinserting,amanualreactorscramwasinsertedat1844CDT.Therootcausewasdeterminedtobealackofperformingelectromagneticandradio-frequencyinterferencenoisetestingtodetectnuclearinstrumentationabnormalities.CorrectiveActiontoPreventRecurrenceistoperformroutinepre-outageandoutage-relatedpreventivemaintenancetasksfornoise-inducedcableteststoverifythenoisehasbeenremoved.NRCFORM366(04-2017)

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-mailtolnfocoIlects.Resourcenrc.gov,andtotheDeskOfficer,OfficeofInformationandRegulatoryAffairs,NEOB-10202,(3150-0104),OfficeofManagementandBudget,Washington,DC20503.Ifameansusedtoimposeaninformationcollectiondoesnotdisplayacurrentlyvalid0MBcontrolnumber,theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformationcollection.1.FACILITYNAMEI2.DOCKETNUMBERI3.LERNUMBERBrownsFerryNuclearPlant,Unit205000-260NARRATIVEI.PlantOperatingConditionsBeforetheEventYEARSEQUENTIALREVNUMBERNO.2017-003-00Atthetimeofdiscovery,BrownsFerryNuclearPlant(BFN),Unit2,wasinMode2atzeropercentpower,aftercompletingarefuelingoutage.II.DescriptionofEventA.EventSummaryOnMarch29,2017,at1842CentralDaylightTime(CDT),duringUnit2start-up,OperationspersonnelreceivedannunciatorsforanIntermediateRangeMonitor(IRM)DownscaleandaControlRodWithdrawalBlock.OperationspersonnelnoticedthatIRM'G'wasreadingdownscaleandadjustedtherangedownonepositionwithnoimmediatereaction.At1844CDT,anupscalespikeonIRM'G'causedahalfscramonReactorProtectionSystem(RPS)'A'tripsystem.AfterverifyingthattheIRM'G'High-Hightripsignalwascleared,OperationspersonnelresetthehalfscramonRPS'A'.Animmediate,concurrenttripsignalfromIRM'F'wasthenreceivedontheRPS'B'tripsystem,resultinginmultiplerodsinsertingintothecore.WhenOperationspersonnelidentifiedmultiplerodsinserting,amanualreactorscramwasinsertedat1844CDT.B.Statusofstructures,components,orsystemsthatwereinoperableatthestartoftheeventandthatcontributedtotheeventTherewerenostructures,systems,orComponentswhoseinoperabilitycontributedtothisevent.C.DatesandapproximatetimesofoccurrencesDates&ApproximateTimesOccurrenceMarch29,2017,BFN,Unit2,achievedcriticality,aspartofstartupactivities.at1651CDTMarch29,2017,OperationspersonnelreceivedannunciatorsforanIRMat1842CDTDownscaleandaControlRodBlockforIRM'G'andadjustedtherangedownonepositionforIRM'G'.March29,2017,lRM'G'readupscalewhenrangeddown,resultinginanat1844CDTunexpectedhalfscramonRPS'A'.TheIRMreadingstabilizedatthishighervalue.OperationspersonnelresetthehalfscramonRPS'A'andatripsignalfromIRM'F'wasreceivedontheRPS'B'tripsystem,resultinginmultiplerodsinsertingintothecore.WhenOperationspersonnelidentifiedmultiplerodsinserting,amanualreactorscramwasinserted.NRCFORM366A(04-2017)Page2of5 NRCFORM366A(04-2017)U.S.NUCLEARREGULATORYCOMMISSIONIAPPROVEDBY0MB:NO.3150-0104EXPIRES:3/31/2020LICENSEEEVENTREPORT(LER)CONTINUATIONSHEETEstimatedburdenperresponsetocomplywiththismandatorycollectionrequest:80hours.Reportedlessonslearnedareincorporatedintothelicensingprocessandfedbacktoindustry.SendcommentsregardingburdenestimatetotheInformationServicesBranch(T-2F43),U.S.NuclearRegulatoryCommission,Washington,DC20555-0001,orbye-mailtolnfocollects.Resource@nrc.gov,andtotheDeskOfficer,OfficeofInformationandRegulatoryAffairs,NEOB-10202,(3150-0104),OfficeofManagementandBudget,Washington,DC20503.Ifameansusedtoimposeaninformationcollectiondoesnotdisplayacurrentlyvalid0MBcontrolnumber,theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformationcollection.I1.FACILITYNAMEI2.DOCKETNUMBERI3.LERNUMBERIYEARSEQUENTIALREVNUMBERNO.BrownsFerryNuclearPlant,Unit205000-2602017-003D.ManufacturerandmodelnumberofeachcomponentthatfailedduringtheeventThefailedcomponentwasaGeneralElectricpre-amplifier,manufacturerpartnumber112C2218G001.E.OthersystemsorsecondaryfunctionsaffectedNoothersystemsorsecondaryfunctionswereaffectedbythisevent.F.MethodofdiscoveryofeachcomponentorsystemfailureorproceduralerrorOperationspersonnelreceivedannunciators,IRMDownscaleandControlRodWithdrawalBlock,foIRM'G'.Additionally,whenOperationspersonnelweredirectedtoresetRPS'A',multiplerodswereinsertingintothecore.G.Thefailuremode,mechanism,andeffectofeachfailedcomponentAfaultypre-amplifier[AMP]gavetheIRM'G'theappearanceofalowsignal.WhenthelRM'G'experiencedaspikeonthisnewsetting,itcausedahalfscram.Thefaultyhigh-voltageconnector[57]anddegradedgroundinginsideoftheIRM'F'drawerallowedforspurioussignalsinductionfromadjacentand/oroverlappingcables.H.OperatoractionsAfteraspikeonIRM'G'causedahalfscramontheRPS'A'tripsystem,Operationspersonnelverifiedthatnotripconditionwaspresent,andmanipulatedtheRPS'A'scramresetswitch.WhenresettingRPS'A',aspuriousIRM'F'signalcausedahalfscramonRPS'B'system.Thiscausedmultiplerodstoinsertintothecore,requiringOperationspersonneltomanuallyscramthereactor.I.AutomaticallyandmanuallyinitiatedsafetysystemresponsesOperationspersonnelinsertedamanualreactorscramuponnoticingmultiplerodsinsertingintothereactor.Ill.CauseoftheeventA.CauseofeachcomponentorsystemfailureorpersonnelerrorTherootcausewasdeterminedtobealackofperformingelectromagneticandradio-frequencyinterferencenoisetestingtodetectabnormalitiesinnuclearinstrumentation.NRCFORM366A(04-2017)Page3of5 NRCFORM366AU.S.NUCLEARREGULATORYCOMMISSIONAPPROVEDBY0MB:NO.3150-0104EXPIRES:3/31/2020(04-2017)Estimatedburdenperresponsetocomplywiththismandatorycollectionrequest:80hours.Reportedlessonslearnedareincorporatedintothelicensingprocessandfedbacktoindustry.SendLICENSEEEVENTREPORT(LER)commentsregardingburdenestimatetotheInformationServicesBranch(1-2F43),U.S.NuclearCONTINUATIONSHEETRegulatoryCommission,Washington,DC20555-0001,orbye-mailtolnfocoIlects.Resource@nrc.gov,andtotheDeskOfficer,OfficeofInformationandRegulatoryAffairs,NEOB-10202,(3150-0104),OfficeofManagementandBudget,Washington,DC20503.Ifameansusedtoimposeaninformationcollectiondoesnotdisplayacurrentlyvalid0MBcontrolnumber,theNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,theinformationcollection.1.FACILITYNAMEI2.DOCKETNUMBERI3.LERNUMBERYEARSEQUENTIALIREVIINUMBERINO.IBrownsFerryNuclearPlant,Unit205000-2602017-003-00IB.Cause(s)andcircumstancesforeachhumanperformancerelatedrootcauseTherewerenohumanperformancerelatedrootcausesassociatedwiththisevent.IV.AnalysisoftheeventTheTennesseeValleyAuthority(WA)issubmittingthiseventinaccordancewithTitle10oftheCodeofFederalRegulations50.73(a)(2)(iv)(A),anyeventorconditionthatresultedinamanualorautomaticactuationoftheRPS.TheconditionwasdiscoveredonMarch29,2017,whenIRM'C'appearedtohaveadownscalesignal,fromwhatwaslaterdeterminedtobearesultofapre-amplifierfailure.UpscalingtheIRM'G'causedanRPS'A'halfscram.SignalnoisefromtheRPS'A'scramresetswitchinadvertentlyinducedacurrentthroughafaultyhighvoltageconnectoronIRM'F'.ThisspuriouscurrentspikeonIRM'F'trippedaRPS'B'half-scramsignal,beforethe'A'signalhadcleared.Uponnoticingcontrolrodmotion,Operationspersonnelwereprocedurallyrequiredtoinsertamanualreactorscram,whichconstitutesareportableevent.V.AssessmentofSafetyConsequencesThiseventresultedinthemanualactuationofasafetysystem.Thiseventdidnotresultintheinoperabilityorunavailabilityofanysystemtoprovidetheirrequiredsafetyfunctions.NoEmergencyCoreCoolingSystems[BC][BJ][BO]orReactorCoreIsolationCooling[BN]reactorwaterlevelinitiationsetpointswerereached.PrimaryContainmentIsolationSystemsdidnotreceiveanactuationsignalandperformedasdesigned.Allsafetysystemsremainedinstandbyreadinessconfigurationandwerecapableofperformingtheirrequiredsafetyfunctions.Therefore,thisconditionhadanegligibleimpactonthehealthandsafetyofthepublic.A.AvailabilityofsystemsorcomponentsthatcouldhaveperformedthesamefunctionasthecomponentsandsystemsthatfailedduringtheeventEachRPStrainhadthreeadditionalIRMswhichremainedoperablethroughoutthisevent.B.Foreventsthatoccurredwhenthereactorwasshutdown,availabilityofsystemsorcomponentsneededtoshutdownthereactorandmaintainsafeshutdownconditions,removeresidualheat,controlthereleaseofradioactivematerial,ormitigatetheconsequencesofanaccidentSafetysystemavailabilitywasnotimpactedbythisevent.C.Forfailurethatrenderedatrainofasafetysysteminoperable,estimateoftheelapsedtimefromdiscoveryofthefailureuntilthetrainwasreturnedtoserviceSafetysystemoperabilitywasnotimpactedbythisevent.NRCFORM366A(04-2017)Page4of5 NRCFORM366AU.S.NUCLEARREGULATORYCOMMISSIONAPPROVEDBY0MB:NO.3150-0104EXPIRES:3131/2020(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.DOCKE1NUMBERIaLERNUMBERYEARISEQUENTIALREVINUMBERINo.IBrownsFerryNuclearPlant,Unit205000-2602017-003-00IVI.CorrectiveActionsCorrectiveActionsarebeingmanagedbyIVA'scorrectiveactionprogramunderConditionReport(CR)1278595.A.ImmediateCorrectiveActionsTroubleshootingwasperformedpriortore-commencingstartup.Duringthateffort,thehighvoltageconnectorintheIRM'F'drawerwasreplaced,andtheIRM'G'pre-amplifierwasreplacedanditsrangeswitchwascorrelated.B.CorrectiveActionstoPreventRecurrenceortoreducetheprobabilityofsimilareventsoccurringinthefutureCorrectiveActiontoPreventRecurrenceistoperformroutinepre-outageandoutage-relatedpreventivemaintenancetasksfornoise-inducedcableteststoverifythenoisehasbeenremoved.VII.PreviousSimilarEventsattheSameSiteAsdescribedinCR558437,asimilareventoccurredonMay24,2012,atBFN,Unit3,duringstartupfollowingarefuelingoutage.TroubleshootingactivitiesidentifiedthatlRM'A'andSourceRangeMonitors(SRMs)'A','C'and'D'receivedperiodalarmsduetoscramresetswitchactuationwithahalfscramsignal.ThesubsequentinvestigationrevealedthatahighvoltagecableintheIRM'A'maincontrolroomdrawerhadabrokeninsulatingshield,andthatthescramresetswitchinducedelectronicnoiseonthecontrolroomcommonground.Thehighimpedanceoftheground,actingthroughthisdegradedconnector,causedanelectronicspikeonIRM'A',leadingtoaRPS'A'actuationwhileOperationspersonnelresetapreviousRPS'B'half-scramsignal,resultinginahalfscram.CorrectivemaintenanceinvolvedaddingferritebeadstotheSRMgroundwiresandtotheresetswitchgroundwire.ItwasdeterminedthattheUnit3IRM'A'andSRMswereonlyvulnerabletoscramresetswitchnoisewhenactuallyresettingavalidhalfscram.Topreventrecurrence,asignificantnumberofconnectorswererepairedorreplacedonallthreeunits.However,theseeffortsdidnotfocusonfindingthenoisecauses,andwereinsufficienttopreventrecurrence.Whilenuclearinstrumentationislargelystandardized,therecanbeunforeseenproblems,especiallyascomponentsdegradeorarereplacedovertime.VIII.AdditionalInformationThereisnoadditionalinformation.IX.CommitmentsTherearenonewcommitments.NRCFORM366A(04-2017)Page5of5