ML17262A566

LER 91-006-00:on 910629,EDG a Started Automatically Due to Apparent Undervoltage Signal from Bus 14 Undervoltage Monitoring Sys.Root Cause Not Determined.Bus 14 Energized & EDG Declared operable.W/910729 Ltr

ML17262A566
Person / Time
Site:	Ginna
Issue date:	07/29/1991
From:	BACKUS W H, MECREDY R C ROCHESTER GAS & ELECTRIC CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-006, LER-91-6, NUDOCS 9108050066
Download: ML17262A566 (16)

Text

ACCELERATEDDISTRIBUTIONDEMON~0TIONSYSTEMREGULATORYINFORMATIONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:9108050066DOC.DATE:91/07/29NOTARIZED:,NOFACIL:50-244RobertEmmetGinnaNuclearPlant,Unit1,,RochesterGAUTH.NAMEAUTHORAFFILIATION.BACKUS,W.H.RochesterGas&ElectricCorp.MECREDY,R.C.'ochesterGas&ElectricCorp.RECIP.NAMERECIPIENTAFFILIATIONDOCKET05000244II

SUBJECT:

LER91-006-00:on910629,EDGAstartedautomaticallyduetoapparentundervoltagesignalfromBus14undervoltagemonitoringsys.Rootcausenotdetermined.Bus14energized&EDGdeclaredoperable.W/910729ltr.DISTRIBUTIONCODE:IE22TCOPIESRECEIVED:LTR!ENCLISIZE:7TITLE:50.73/50.9LicenseeEventReport(LER),IncidentRpt,etc.NOTES:LicenseExpdateinaccordancewith10CFR2,2.109(9/19/72).D05000244ARECIPIENTIDCODE/NAMEPD1-3LAJOHNSON,AINTERNAL:ACNWAEOD/DSP/TPABNRR/DET/ECMB9HNRR/DLPQ/LHFB10NRR/DOEA/OEABNRR/DST/SELBSDNRRfDST~LBSD1REGF~02RGN1FILE01EXTERNAL:EG&GBRYCE,J.HNRCPDRNSICPOORE,W.~7&75Htt<w'(COPIESLTTRENCL111122111111111111111'1331111RECIPIENTIDCODE/NAMEPD1-3PDAEOD/DOAAEOD/ROAB/DSPNRR/DET/EMEB7ENRR/DLPQ/LPEB10NRR/DREP/PRPB11NRR/DST/SICBSH3NRR/DST/SRXBSERES/DSIR/EIBLSTLOBBYWARDNSICMURPHY,G.ANUDOCSFULLTXT'OPIESLTTRENCL111122111122111'11111111DDDNOTETOALL"RIDS"RECIPIENTS:PLEASEHELPUSTOREDUCEWASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOiv!P1-37(EXT.20079)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLISTSFORDOCU5!EiiTSYOUDON'TNEED!ADDSFULLTEXTCONVERSIONREQUIRED-TOTALNUMBEROFCOPIESREQUIRED:LTTR31ENCL31

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Subject:

LER91-006,ApparentVoltageDroponSafeguards480VoltBus14CausesanAutomaticStartofthe"A"EmergencyDieselGeneratorR.E.GinnaNuclearPowerPlantDocketNo.50-244In-accordancewith10CFR50.73,LicenseeEventReportSystem,item(a)(2)(iv),whichrequiresareportof,"anyeventorconditionthatresultedinmanualorautomaticactuationofanyEngineeredSafetyFeature(ESF),"includingtheReactorProtectionSystem(RPS)",theattachedLicenseeEventReportLER91-006isherebysubmitted.Thiseventhasinnowayaffectedthepublic'shealthandsafety.Verytrulyyours,RobertC.MecrdyxcU.S.NuclearRegulatoryCommissionRegionI475AllendaleRoadKingofPrussia,PA19406GinnaUSNRCSeniorResidentInspector9i080s00g,(,PDRADOCKOrt.iot)-4i

NACtaslliIOACILICENSEEEVENTREPORT(LERIUANUOLCAAAoovLATCAocc>>se&lcwAttleovtooleoNILOINolovCAOIACO.O)te/~$)ACILITYNA<<)OIllR.E.GinnaNuclearPower.PlantOOCACTeeveeoCAOlo6ooo244iosApparentVoltageDmpOnSafequards480VoltBus14CausesanAutomaticStartoftheA"EmerencDieselGeneratorCVCIITCATO14Lt1NveeocA14Al)O1TOATClllOTlet1)ACILITICCINVOLVCOIOI>>OI>>T>>eOAYYCAAYCAA~COveeee>>AL>>eV>>l11NONTNOAYYCAA)ACIUTYMA>>elAOOCACTAve)il1140600O062991910060007299106000Otl1ATIIIOe)OOtNl~OeeCALtvlL0e~r<<jM<+d>>%wII>>".TIIIC1l)01TICVO<<IITTCO)VACVANTTCO.<<OCNICO.<<OOleIIIII~CO.OOOleIllIIIITo.eoc4IIIII>>ITOAOOlelllllleltiOOCI)IIIIIelTt.eotlelNWI)IIIINMNIICIN.TCNI0IION.TC4IItII~IN.T$4IICIIWlN.'IQeIltl(NI=N.TONIICllelN.TONIICIleoIN.TC4IICIleeNW~O.TONIItlIeellICIN.TCNIltlleloTNC1covl1t<<ICNTootIoct1$:lc<<eeo<<eeaoeaoo)o>>Ia>>ooe)I0IT%7141TC.1141OTlet1li)o)OVleAAeoeee~<<o>>e<<tSTe)L<<ACl<<sLICtNCCCCONTACT)OATillLt1Iltl>>A<<etWesleyH.BackusTechnicalAssistanttotheOperationsManagerAIIOACOOlTILC)leONCNVQOCA31524-4446COeetLCTCONCLINC)01CAC>>lCO<<e)ONCNT)AILUACOtlC1IOCOINTNICAtt01TlltlcAvlcCYOTC<<ecoco)oNCNTe)ANvtAcTVACActoATACLC.+:"ke~~+pju>>.~'TOIe)AOC>>Aj~Yn~k,ee>>'~Qg,CAVltCYOTCIIs'>>>>>>'ehv+v;o>>>>~(e>>Q+PP+c~p,COee)ONCNT>>ANVtAC,TUACACV)YLC4CNTALAttOATCA)CCTCOIlel'YCCIIItee,e<<ee<<e>>CA)CCTCOCV)<<IICCIONCATO)XNO<<ACTAAcTIL<<evls1)00eoas,Ieeooeoeeev>>I)III>>oee<<etvvoeeeItoeeee>>I>>o<<esl114t1)CCTCOwo<<elttloNOATCIlllIIONT>>eCAYYCANOnJune29,1991at1754ESTwiththereactoratapproximately98%fullpower,the"A"EmergencyDieselGeneratorstartedautomaticallyduetoanapparentundervoltagesignalfromtheBus14UndervoltageMonitoringSystem.The"A"EmergencyDieselGenerator,afterstarting,attainedpropervoltageandfrequency.Bydesign,itdidnotcloseintoBus14becauseBus14wasatitspropervoltageandbeingfedfromitsnormalpowersupply.ImmediateoperatoractionwastoverifythatBus14wasenergizedandthatthe"A"EmergencyDieselGeneratorwasoperatingnormally.Subsequently)the"A"EmergencyDieselGeneratorwasstoppedandrealignedforauto-standby.Thecauseoftheeventhas.notbeenpositivelydetermined,althoughoff-siteelectricaldisturbanceispostulated.Sincethecauseofthiseventhasnotbeenpositivelydeterminedatthistime,wewillcontinuetoinvestigatefortheunderlyingcause.Anyfurthercorrectiveactionwilldependonthere'suitsofthisinvestigation.eeACtoesONIOACI

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~e~H(ICFMmdddA(045)L'ICENSEEEVENTREPORTILERITEXTCONTINUATION3U.d.HUCLCA(IHKOULATOHYCOMM(dd(OHAFFHOVEOOMdHO5150M(04dkF(Added(5((55FACILITYHAMd(IIR.E.GinnaNuclearPowerPlantTEXTIN'cccMcccHmdvckd.vccNMcckncc(4(NCFckmJ(d(4'cl((T(OOC((ETHUMddll(1(0s00024491Ld(IHUMddll(dl5~OVCHZIAL4HVMk-006kdVMIOHHUM0FAOd(5102DFO6PRE-EVE2iTPLANTCONDITIONSTheplantwasatapproximately984steadystatefullpowerwithno'ajoractivitiesinprogress.II.DESCRIPTIONOF%TENTA.DATESANDAPPROXIMATETIMESOPMAJOROCCURRENCES:000June29,1991,1754EDST:EventDateandTimehJune29,1991,1754EDST:DiscoveryDateandTimeJune29,1991,2013EDST:"A"EmergencyDieselGeneratorstoppedandrealignedforAuto-standbyB.EVENT:OnJune29,1991at1754EDST,withthereactoratapproximately98%fullpower,theControlRoomreceivedthefollowingalarms:L-14(Bus14.Undervoltage-Safeguards)andJ-24(EmergencyDieselGen1APanel).TheControlRoomoperatorsimmediatelyverifiedpropervoltageonBus14andthatthenormalpowersupplybreakerwasclosed.TheControlRoomoperatorsalsoverifiedthatthe"A"EmergencyDieselGeneratorhadstartedanddisplayedpropervoltageandfrequency.Bydesign,the"A"EmergencyDieselGeneratordidnotcloseintoBus,14,asthebusvoltagewasnormalandBus14wasstillbeingsuppliedbyitsnormalpowersupply.HACFOAM544*(Iddl

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~0~eNRCSotw295A(042IL'ICENSEEEVENTREPORTILERITEXTCONTINUATIONU.S.NUCLEARREQVLATORYCOMMI55IONASSROVEOOM9NOSISOWI04JEXSIRES,9121/99SACILITYNAME111OOCKETNVMEER121LERNVMQEII19155QUENTIALNUMREVISIONNUMSAOEl21R.E.GinnaNuclearPowerPlantTEXTIIJ~<<>>5~N~.v>>NAS55JNJHRCFOnn2OEA'5IIITIo5ooo244,0060003pF06Subsequently,AuxiliaryoperatorsweredispatchedtochecktheBus14UndervoltageMonitoringSystemcabinetsandtheoperationofthe"A"EmergencyDieselGenerator.Theoperationofthe"A"EmergencyDieselGeneratorwasfoundtobenormal.NoundervoltagetriptargetswereobservedonBus14orBus18(boththesebusesarefedbythe"A"Emergency.DieselGenerator).Duringthisevent,routineactivitieswereoccurringatoff-siteStation204.AtapproximatelythesametimeastheapparentundervoltageconditionoccurredonBus14,a34.5kvcapacitorbankwasbeingremovedfromservice.Thisisaroutineactiontocorrectoff-sitevoltagesituations.Station204'eedsCircuit751,whichwasthenormaloff-sitepowersupplytoBuses14and18.Control=RoomoperatorsnotifiedhighersupervisionandtheNuclearRegulatoryCommissionoftheevent.ToproveoperabilityoftheUndervoltageMonitoringSystem,theResultsandTest(R&T)DepartmentperformedPeriodicTestprocedurePT-9.1(UndervoltageProtection480VoltSafeguardsBusses)onBus14.AfterPT-9.1.wassuccessfullycompleted,the"A"EmergencyDieselGeneratorwasstoppedandrealignedforAuto-standby.C.INOPERABLESTRUC'HIRES,COMPONENTSsORSYSTEMSTHATCONTRIBUTEDTOTHEEVENT:None.D.OTEGsRSYSTEMSORSECONDARYPUNCTIONSAFFECTED:E.None.METHODOPDISCOVERY:TheeventswereimmediatelyapparentduetoalarmsandindicationsintheControlRoom.NRCSORM255AI94ll

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<<ACSottoSSSA~eL'ICENSEEEVENTREPORT(LER)TEXTCONTINUATIONV,S.<<UCLEAIIIlfOULATOIIYCOMMISSIOIIASSAOYEOOMSHO3150MIOIIEXSIAES,SISIl95SACILITYNAMEIllR.E.GinnaNuclearPowerPlantTEXTillnave<<WCe<<nquseCvASOdakevWlYPCArm~'llIITIOOCKETIIUMSEII11Iosooo24LEII<<UMSEIIISI5~4UC<<VIAL'SV<<IONHUM<<'"<<UMf<<9-1-006-00~AOSISI04o~06F.OPERATORACTXON:FollowingtheBus14UndervoltageAlarmandthe"A"EmergencyDieselGeneratorautomaticstart,theCo'ntrolRoomoperatorsimmediatelyverifiedpropervoltageonBus14viathenormalpowersupplyand',thatthe"A"EmergencyDieselGeneratordisplayedpropervoltageandfrequency.Subsequently,Auxiliaryoperatorsweredis'patchedtocheck-theBus14undervoltagemonitoringsystemand"A"EmergencyDieselGeneratoroperation.The"A"EmergencyDieselGeneratoroperationwasnormaland,noundervoltagetriptargetswereobservedonBus14orBus18.'t"The"A"EmergencyDieselGeneratorwassubsequentlystoppedandrealignedforAuto-standby.G.SAFETXSXSTEMRESPONSES:The"A"EmergencyDieselGeneratorautomaticallystartedanddisplayedpropervoltageandfrequency.'IXI.CAUSEOFEV19Fl'.XMM1sDIATECAUSE:Theautomaticactuationofthe-"A"EmergencyDieselGeneratorwasduetoanapparentundervoltagesignalfromtheBus14undervoltagemonitoringsystem.B.ROOTCAUSE:Theunderlying,causeoftheapparentundervoltagesignalfromtheBus14undervoltagemonitoringsystemisnotpositivelydeterminedatthistime..MACSO<<MSSSAI941l

~0 IIACSovvvv444A14451~eoeL'ICENSEEEVENTREPORT(LERITEXTCONTINUATIONU,E.NUCLEAAAEOULATOAYCOMMIEEIOII/ASSAOVEOOMEIVO1150MIOeEXSIAES,4151/45SACILITYIIAMEIllR.E.GinnaNuclearPawerPlantTExTlllnaveMeceaeevveevLvvMvneeevalvYACSevvnSELAYlIITICOCKETIvUMEEA111osooo244vEAALEIIIIUMEEA14154004VVTIAL~VUM006ntvlelOMVVVM00SAOEIEI050F06IV.ANALYSISOFEVENTTheeventisreportableinaccordancewith10CFR50.73,LicenseeEventReportSystem,item(a)(2)(iv),whichrequires'eportingof,"anyeventorconditionthatresultedinmanualorautomaticactuationofanyEngineeredSafetyFeature(ESF)includingtheReactor.ProtectionSystem(RPS)".Thestartingofthe"A"EmergencyDieselGeneratorwasanautomaticactuationofanESFsystem.Anassessmentwasperformedconsideringboththesafetyconsequencesandimplicationsofthiseventwiththefollowingresultsandconclusions:Therewerenooperationalorsafetyconsequencesorimplicationsattributedtothestartingofthe"A"EmergencyDieselGeneratorbecause:0The"A"EmergencyDieselGeneratoroperatedasdesigned.oBothBus14powersupplies(i.e.normalandemergency)wereeitherinuseoravailablethroughouttheevent.oTheBus14undervoltagemonitoringsystemoperationwasintheconservativedirection,(i.e.theoperationactuatedtheautomaticstartofthe"A"EmergencyDieselGenerator).Basedontheabove,itcanbeconcludedthatthepublic'shealthandsafetywasassuredatalltimes.V.CORRECTIVEACTIONA.ACTIONTAKENTORETURNAFFECTEDSYSTEMSTOPRE-EVENTNORMALSTATUS:oTheR&TDepartmentsuccessfullycompletedPT-9.1onBus14andthe"A"EmergencyDieselGeneratorwasstoppedandalignedforAuto-standby.~VACS0VIM544A14411

~1~0 NAC>armSEEAIHEI~0I.'ICENSEEEVENTREPORT(I.ER)TEXTCONTINUATIONV.S.NVCLEAIIIIEOVLATOIIYCOMMISSIONIAtfAOVEOOMEHO$1$0MIOIE)CrllIES.EISI4$FACILITYNAMEIIIOOCIIETNVMEEIIIEIYEAALEIINVMEEIIIEIIEQVEHTIAL4MIAAEVISIO<NVMIA~ACEISIR.E.GinnaNuclearPowerPlantTEILillmortapeceemewaf.wtaAkenVHACFiwnDELI'IlIITlosooo.244910060006'F06B.ACTXONTAKENORPLANNEDTOPREVENTRECURRENCE:000Astheunderlyingcauseoftheeventhasnotbeendeterminedatthistime,investigationswillcontinuetopositivelydeterminetheunderlyingcauseofthisevent.Anyfurthercorrectiveactionswilldependontheresultsoftheseinvestigations.Electricalsystemmonitoringrecordshavebeenreviewed,andindicatethatremovalofthecapacitorbankresultedinasmallandroutinevoltagetransient.ElectricalsystemmonitoringhasbeenincreasedonCircuit751.0Theinterfacebetweentheundervoltagemonitoringsystemanddieselstartcircuitrywillcontinuetobeevaluated,'todetermineiftheundervoltagesystemisreactingasdesignedforsmallvoltagefluctuations.ADDXTXONALXNFORMATIONA.B.PAXLEDCOMPONENTS:None.PREVXOUSLERsONSIMILAREVENTS:AsimilarLEReventhistoricalsearchwasconductedwiththefollowingresults:NodocumentationofsimilarLEReventswithanundeterminedrootcauseatGinnaStationcouldbeidentified.C.SPECIALCOMMENTSNone.%ACSOIIMSEEAISAl

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