ML17264B127

LER 97-005-00:on 971031,undetected Unblocking of SI Actuation Signal Occurred at Low Pressure Condition,Due to Faulty Bistable Which Resulted in Inadvertent SI Actuation Signal.Sias,Ci & Cvi Signals Were Reset

ML17264B127
Person / Time
Site:	Ginna
Issue date:	12/01/1997
From:	MARTIN J T ROCHESTER GAS & ELECTRIC CORP.
To:
Shared Package
ML17264B126	List: ML17264B125 ML17264B127
References
LER-97-005, LER-97-5, NUDOCS 9712050136
Download: ML17264B127 (9)

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NRCFORM366(4-95)U.S.CLEARREGULATORYCOMMISSIOLICENSEEEVENTREPORT(LER)(Seereverseforrequirednumberofdigits/charactersforeachblock)I'PROVEDBYOMBNO.3150-0104EXPIRES04/30/96ESTIMATEDBURDENPERRESPONSEToCOMPLYWITHTHISMANDATORYINFORMATIONCOLLECTIONREQUEST:50.0HRS.REPORTEDLESSONSLEARNEDAREINCORPORATEDINTOTHELICENSINGPROCESSANDFEDBACKToINDUSTRY.FORWARDCOMMENTSREGARDINGBURDENESTIMATETo.THEINFORMATIONANDRECORDSMANAGEMENTBRANCHIT-6F33),U.s.NUCLEARREGULATORYCOMMISSION,WASHINGTON,DC20555-0001,ANDToTHEPAPERWORKREDUCTIONPROJECTFACILITYNAME(1)TITLE(4IR.E.GinnaNuclearPowerPlantDOCKEfNUMBER(2I05000244PAGE(3I1OF7UndetectedUnblockingofSafetyInjectionActuationSignalWhileatLowPressureCondition,DuetoFaultyBistable,ResultedinInadvertentSafetyInjectionActuationSignalMONTHDAYYEAR103197EVENTDATE(5)LERNUMBER(6)SEQUENTIALREVISIONNUMBERNUMBER97-005-00REPORTDATE(7)MONTHDAYYEAR120197FACILITYNAMEFACIL(ryNAMEOTHERFACILITIESINVOLVED(6)DOCKETNUMBERDOCKETkUMSEROPERATINGMODE(9)POWERLEVEL(10)000SUANTTOTHEREQUIREMENTSOF10CFRE:(CheckoneorTHISREPORTISSUBMITTEDPUR20.2201(b)20.2203(a)(1)20.2203(a)(2)(i)20.2203(a)(2)(ii)20.2203(a)(2)(nr)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)X50.73(a)(2)(iv)50.73(a)(2)(v)50.73(a)(2)(vii)more)(11)50.73(a)(2)(viii)50.73(a)(2)(x)73.71OTHERSpecifyInAbstractbeloworinNRCForm366ANAMELICENSEECONTACTFOR'THISLER(12)TELEPHONENUM8ER(IncrudeAreaCode)JohnT.St.Martin-TechnicalAssistantCOMPLETEONELINEFOREACHCOMPONENTFAILUREDES(716)771-3641CRIBEDIN'THISREPORT(13)CAUSESYSTEMCOMPONENTMANUFACTURERREPORTABLEToNPRDSCAUSESYSTEMCOMPONENTMANUFACTURERREPORTABLETONPRDSJEJSF180NOSUPPLEMENTALREPORTEXPECTED(14)YES(Ifyes,completeEXPECTEDSUBMISSIONDATE).XNOEXPECTEDSUBMISSIONDATE(15)MONTHDAYYEARABSTRACT(Limitto1400spaces,i.e.,approximately15single-spacedtypewrittenlines)(16)OnOctober31,1997,atapproximately1640EST,theplantwasinMode6withthereactorcoolantsystembeingmaintainedatatemperatureof80degreesF,andthereactorcavityfilledtogreaterthan23feet.Theplantwasshutdownforrefueling.AninadvertentautomaticSafetyInjectionActuationoccurred.Immediatecorrectiveactionwastomonitortheautomaticstartofengineeredsafetyfeaturescomponentsandsecureunneededequipment.TheunderlyingcauseoftheinadvertentautomaticSafetyInjectionActuationwasanundetectedfaultybistablecircuitboard.Duringtheperformanceofaperiodictest,thisfaultybistablecausedtheSafetyInjectionActuationsignaItobeinadvertentlyunblockedwithpressurizerpressurelessthanthesetpointforSafetyInjectionActuation.CorrectiveactiontoprecluderepetitionisoutlinedinSectionV.B.97i2050i3697i20iPDRADQCK05000244SPDRNRCFORM366(4-95)

NRCFORM366A(4-95)LICENSEEEVENTREPORT(LER)TEXTCONTINUATIONU.s.NUCLEARREGULATORYCOMMISSIONFACILITYNAME(1)R.E.GinnaNuclearPowerPlantDOCKET05000244LERNUMBER(6)YFARSEQUENTIALREVISIONNUMBERNUMBER97-005-00PAGE(3)2OF7TEXTIifmorespeceisrequired,useedditionelcopiesofNRCForm366AI(17)PRE-EVENTPLANTCONDITIONS:OnOctober31,1997,theplantwasinMode6withthereactorcoolantsystem(RCS)beingmaintainedatatemperatureofapproximately80degreesF,andthereactorcavityfilledtogreaterthan23feet.Bothresidualheatremoval(RHR)pumpswereoperating,andfuelmovementwasonhold.Twoservicewater(SW)pumpswereoperating.Theplantwasshutdownforrefueling.PerformanceMonitoringtechnicianswereconductingperiodictestprocedurePT-32.1(PlantSafeguardLogicTestAorBTrain).Testingofthe"B"trainwasstartedatapproximately1606EST.AspartoftheconductofprocedurePT-32.1,simulatedsignalsareinsertedtoprovidenormalrelaystatesformiscellaneoussignals.Priortoinsertingthesesignals,individualsfromPerformanceMonitoringandInstrumentandControl(ILC)verifiedthatindicationswereappropriateontheMainControlBoard,insafeguardsracksintheRelayRoom,andinprotectiveracksintheControlRoom.IRCtechniciansthenperformedthesesimulationsinaccordancewithprocedurePT-32.1.IRCconnectednon-poweredtransmittersimulatorstothreepressurizer(PRZR)pressurechanneltestinjectionjacks(forchannelsP-429,P-430andP-431).TestinjectionswitchesforP-429andP-430weretakentothetestpositionandsimulatoroutputwascheckedforthedesiredoutput.DESCRIPTIONOFEVENT:A.DATESANDAPPROXIMATETIMESOFMAJOROCCURRENCES'ctober31,1997,1606EST:PerformanceMonitoringstartsprocedurePT-32.1for"B"train.October31,1997,1640EST:Eventdateandtime.October31,1997,1640EST:Discoverydateandtime.October31,1997,1643EST:SafetyInjectionActuationandContainmentIsolationsignalsarereset.October31,1997,1649EST:ContainmentVentilationIsolationsignalisreset.October31,1997,1700EST:Pre-eventrefuelingshutdownconditionsarerestored.B.EVENT:OnOctober31,1997,theplantwasinMode6withtheRCSbeingmaintainedatatemperatureofapproximately80degreesF,andthereactorcavityfilledtogreaterthan23feet.Theplantwasshutdownforrefueling.TheSafetyInjection(Sl)ActuationSignal(SIAS)is,providedwithablocksignalwhichpreventsaSIASfromoccurringforLowPRZRPressure.SIASwasblocked,whichisthenormalconfigurationwhenPRZRpressureisintentionallyreducedbelowtheSIASsetpointduringplantshutdownconditions.NRCFORM366A(4.95)

NRCFORM366AI4-95)LICENSEEEVENTREPORT(LER)TEXTCONTINUATIONU.S.NUCLEARREGULATORYCOMMISSIONFACILITYNAMEI1)R.E.GinnaNuclearPowerPlantDOCKET05000244LERNUMBERI6)YEARSEQUENTIALREVISIONNUMBERNUMBER97-005-00PAGEI3)3OF7TEXT(Ifmorespaceisrequired,useadditionalcopiesofNRCForm366A/(17)Atapproximately1640EST,I&Ctechnicianstookthethirdchannel(P-431)testinjectionswitchtothetestposition.Immediatelyaftertheswitchwasinthetestposition,simulatoroutputwasobservedtobeapproximately30milliamperes,whichsimulatespressureabovetheunblocksetpointof1992PSIG.ThisresultedinunblockingSIASfromLowPRZRPressure.ThisalsoresultedinSlactuationonLowPRZRPressure.TheControlRoomoperatorsimmediatelyrespondedtotheinadvertentSlactuation.TheyrespondedtoMainControlBoardannunciatorD-19(PressurizerLoPressSl1750PSIG).TheyconfirmedthatautomaticSlactuationhadoccurredandverifiedthatalloperableengineeredsafetyfeatures(ESF)componentsfunctionedproperly.NoimmediateactionswererequiredfortheRCS,sincethereactorcavitylevelremainedstable.TheControlRoomoperatorsreferredtoemergencyoperatingproceduresE-0(ReactorTriporSafetyInjection)andES-1.1(SlTermination)forguidanceinsecuringandrestartingequipment.BothRHRpumpscontinuedtooperate,andthetwoselectedSWpumpsstarted.The"A"emergencydieselgenerator(EDG)startedanddidnotenergizeanybusses,sinceallsafeguardsbussesremainedenergizedfromoff-sitepower.AllotheroperableESFcomponentswerealsoobservedtofunctionproperly,withtheexceptionofvalvepositionforair-operatedvalveAOV-5392(instrumentairtocontainmentisolationvalve).Thevalvepositionindicatedbothopenandclosed.However,subsequentinvestigationconfirmedthatthevalvedid,infact,traveltothefullyclosedposition.Duetoplantconditions,manyESFcomponentswerenotoperableatthestartofthisevent.The"B"EDGwasinoperableforperiodicmanufacturerinspectionandoverhaul.AllthreeSIpumpswererenderedinoperable.Therefore,the"B"EDGdidnotstartandnoSlpumpsstarted.NoinjectionflowfromtheSlpumpstotheRCSoccurred.I&CremovedthesafeguardstrainDCsupplyfusestopreventare-occurrenceofSlactuation.I&Cthencommencedtrouble-shootingforthecauseoftheSlactuation.Subsequentrootcauseanalysisrevealedthat,priortothisactivity,therehadbeenafaultinbistablecircuitboardPC-430E/F.Thisundetectedfaultresultedinthebistablede-energizing.Ade-energizedoutputresultsinbotha1/3UnblockSlsignalanda1/3LowPRZRPressureSlsignal.TheSIASforLowPRZRPressurewasautomaticallyunblockedassoonasasecondchannel(theP-431simulatedsignal)wassimulatedabovetheunblocksetpoint,sinceafirstchannel(failedchannelP-430)wasalreadyinsertinganunblocksignal.SimulatedPRZRpressure(asmeasuredbychannelP-429)wasbelowthesetpointforautomaticSIAS(thusinsertinga1/3LowPRZRPressureSlsignal).ThefaultedchannelP-430wasalsoinsertinga1/3LowPRZRPressureSlsignal.This2/3SlsignalwasblockeduntiltheP-431simulatoroutputwasinserted.Atthatinstant,the2/3signalwasunblocked,resultinginautomaticSIactuationfrom2/3LogicforPRZRpressurelessthan1750PSIG.AutomaticSlactuationcausedautomaticactuationofCNMTIsolation(Cl)andCNMTVentilationIsolation(CVI).NRCFORM366A(4.95)

I NRCFORM366AI4.95)LICENSEEEVENTREPORT(LER)TEXTCONTINUATIONU.S.NUCLEARREGULATORYCOMMISSIONFACILITYNAMEI1)R.E.GinnaNuclearPowerPlantDOCKET05000244LERNUMBERIB)YEARSEQUENTIALREVISIONNUMBERNUMBER97-005-00PAGEI3)4OF7TEXTllfmorespaceisrequired,useadditionalcopiesofIVRCForm366A/(17)INOPERABLESTRUCTURES,COMPONENTS,ORSYSTEMSTHATCONTRIBUTEDTOTHEEVENT:Trouble-shootingbyl&CidentifiedthatbistablePC-430E/Fhadablownfuse,whichcauseditsoutputstobede-energized.Nooutputfromthisbistable(de-energizedstate)providesa1/3UnblockSland1/3LowPRZRPressureSlsignal.D.OTHERSYSTEMSORSECONDARYFUNCTIONSAFFECTED:NoneE.METHODOFDISCOVERY:ThiseventwasimmediatelyapparentduetonumerousMainControlBoardAnnunciatoralarmsintheControlRoom.F.OPERATORACTION:TheControlRoomoperatorsrespondedtotheAnnunciatoralarms.TheydiagnosedthatautomaticSlactuationhadoccurred,andverifiedthatalloperableESFcomponentsfunctionedproperly.TheyobservedthedualpositionindicationforAOV-5392andconfirmedthatInstrumentAirtoCNMThadbeenproperlyisolated.TheControlRoomoperatorsresettheSIASandClandCVIsignals.Unneededequipmentwassecured.AllClvalvesandCVIcomponents(whichchangedpositionduetotheSIactuation)werereturnedtotheirpositionspriortotheevent.Pre-eventconditionswererestored.Subsequently,theControlRoomoperatorsnotifiedhighersupervisionandtheNRC.TheShiftSupervisornotifiedtheNRCper10CFR50.72(b)(2)(ii),non-emergencyfourhournotification,atapproximately1946ESTonOctober31,1997.G.SAFETYSYSTEMRESPONSES:Allsafetysystemsandcomponentsthatwereoperablerespondedasdesigned,exceptthatthevalvepositionindicationforAOV-5392indicatedbothopenandclosed.AllotheroperableESFcomponentswereobservedtofunctionproperlyaftertheautomaticSlactuation.ThisincludedautostartoftwoSWpumpsandthe"A"EDG.NRCFORM366AI4.95)

NRCI'ORM366A(4.95)LICENSEEEVENTREPORT(LER)TEXTCONTINUATIONU.S.NUCLEARREGULATORYCOMMISSIONFACILITYNAME(1)R.E.GinnaNuclearPowerPlantDOCKET05000244LERNUMBER(6)YEARSEQUENTIALREVISIONNUMBERNUMBER97-005-00PAGE(3)5OF7TEXTIffmorespaceisrequired,useeddidonalcopiesofNRCForm386A/(17)III.CAUSEOFEVENT:A.IMMEDIATECAUSE:TheimmediatecauseoftheinadvertentautomaticSlactuationwasfrom2/3logicfromLowPRZRPressurewithSIASunblocked.B.INTERMEDIATECAUSE:TheintermediatecauseofautomaticSIASbeingunblockedwassimulatingthesignalfor'PRZRchannelP-431SlUnblocktobeabovetheunblocksetpointwithaconcurrentundetectedfaultinchannelP-430.ROOTCAUSE:TheunderlyingcausewasfaultybistablecircuitboardPC-430E/FonchannelP-430,whichfunctionstoprovide1/3UnblockSlsignalsand1/3LowPRZRPressureSlsignals.Inbothcases,thebistablede'-energizestoprovidethisfunction.Thebistable'ssupplyfusehadblownandcausedbothsignaloutputstogotozero.Thiscausedthesafetysystemtoseea1/3signalforunblockingandforinitiatingSl.WhenchannelP-431wassimulated,theoutputwasgreaterthantheunblocksetpoint,soSIASwasunblockedfrombothP-430(faulted)andP-431(simulated).ThiseventisNUREG-1022CauseCode(B),"Design,Manufacturing,Construction/Installation".IV.ANALYSISOFEVENT:Thiseventisreportableinaccordancewith10CFR50.73,LicenseeEventReportSystem,item(a)(2)(iv),whichrequiresareportof,"Anyeventorconditionthatresultedinamanualorautomaticactuationofanyengineeredsafetyfeature(ESF)".TheinadvertentautomaticSIactuationisanautomaticactuationofanESF.Anassessmentwasperformedconsideringboththesafetyconsequencesandimplicationsofthiseventwiththefollowingresultsandconclusions:TherewerenooperationalorsafetyconsequencesorimplicationsattributedtotheinadvertentautomaticSlactuationbecause:~TheplantwasinMode6(refuelingshutdownmode)withhighheadSlpumpsrenderedinoperable.TheRHRsystemwasalignedfordecayheatremoval,andsteamgenerator(SG)nozzledamswereinplace.NRCFORM366A(4-95)

NRCFORM366A(4-95)U.S.NUCLEARREGULATORYCOMMISSIONFACILITYNAMEI1)LICENSEEEVENTREPORT(LER)TEXTCONTINUATIONDOCKETLERNUMBERI6)PAGEI3)R.E.GinnaNuclearPowerPlant05000244YEARSEQUENTIALREVISIONNUMBERNUMBER6OF797-005-00TEXT(Ifmorespaceisrequired,useadditionalcopiesofNRCForm366A/(17)~Plantconditionsprecludedanyover-pressurecondition.Theheadwasremovedfromthereactorandthereactorcavitywasfilledtogreaterthan23feet.AllSlpumpswereinoperableandtheRefuelingWaterStorageTankwasnotalignedtothesuctionoftheRHRpumps.TherewasnoadditionofwaterinventorytotheRCS.RCStemperaturecontinuedtobemaintainedstableviatheRHRsystem.Therefore,reactivitywasnotaffectedbyRCStemperaturechanges.~TheSWsystemandComponentCoolingWatersystemremainedinserviceduringthisevent,providingadequatecoolingtotheRCSandSpentFuelPool.~TheRHRcoolingcapabilityremainedinserviceandRCSintegritywasmaintained.Therefore,heatremovalfromthereactorwasassured.Basedontheabove,itcanbeconcludedthatthepublic'shealthandsafetywasassuredatalltimes.V.CORRECTIVEACTION:A.ACTIONTAKENTORETURNAFFECTEDSYSTEMSTOPRE-EVENTNORMALSTATUS:IRCdecreasedthesimulatedoutputforP-431tobelowtheSlunblocksetpoint,thusterminatingtheSIUnblocklogic,andallowingtheControlRoomoperatorstoagainblockSIAS.TheSIAS,Cl,andCVIsignalswerereset.Unneededequipmentwassecured.AllClvalvesandCVIcomponents(whichchangedpositionduetotheSlactuation)werereturnedtotheirpositionspriortotheevent.Pre-eventconditionswererestored.B.ACTIONTAKENORPLANNEDTOPREVENTRECURRENCE:AmethodtovisuallyindicateSlUnblockstatusfromPRZRpressurewillbeevaluated.Thefaultybistablecircuitboardwasreplacedwithalikeforlikereplacement,andcalibratedandtestedsatisfactorily.CPI-TRIPTEST-5.20(ReactorProtectionSystemBistableTripTest/CalibrationforChannel2(White)BistableAlarms)wascompletedforallChannel2,Rack1bistablestocheckforproperoperationandtoverifytherewerenootherbistableswithsimilarfaults.Nootherfaultybistableswereidentified.NRCFORM366AI495)

NRCFORM366A(4.95)U.S.NUCLEARREGULATORYCOMMISSIONFACILITYNAME(1)LICENSEEEVENTREPORT(LER)TEXTCONTINUATIONDOCKETLERNUMBER(6)PAGE(3)R.E.GinnaNuclearPowerPlant05000244YEARSEQUENTIALREVISIONNUMBERNUMBER97-005-007OF7TEXTllfmorespaceisrequired,useadditionalcopiesofNRCForm366Al(17)VI.ADDITIONALINFORMATION:A.FAILEDCOMPONENTS:NonePREVIOUSLERsONSIMILAREVENTS'similarLEReventhistoricalsearchwasconductedwiththefollowingresults:nodocumentationofsimilarLEReventswiththesamerootcauseatGinnaStationcouldbeidentified.However,thefollowingLERsweresimilareventswithdifferentrootcauses:~LER84-006~LER85-004~LER89-003~LER95-003C.SPECIALCOMMENTS'oneNRCFORM366A(495)