ML17328B014

LER 91-004-00:on 910313,reactor Tripped as Result of Turbine Trip Generated by Moisture separator-reheater High Water Level Trip.Caused by Ice & Snow Damaging Transmission Lines. Insp Performed on Governor & Steam traps.W/910412 Ltr

ML17328B014
Person / Time
Site:	Cook
Issue date:	04/12/1991
From:	BLIND A A, CARTEAUX P F INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-004, LER-91-4, NUDOCS 9104180309
Download: ML17328B014 (6)

Text

ACCELERATEDSTRIBUTIONDEMONSTRATIONSYSTEMREGULATORYINFORMATIONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:9104180309DOC.DATE:91/04/12,NOTARIZED:NODOCKET¹FACIL:50-316DonaldC.CookNuclearPowerPlant,Unit2,Indiana&05000316AUTH.NAME.AUTHORAFFILIATIONCARTEAUX,P.F.IndianaMichiganPowerCo.(formerlyIndiana&MichiganEleBLIND,A.A.IndianaMichiganPowerCo.(formerlyIndiana&MichiganEleRECIP.NAMERECIPIENTAFFILIATION

SUBJECT:

LER91-004-00:on910313,reactortrippedasresultofturbinetripgeneratedbymoistureseparator-reheaterhighwaterleveltrip.Causedbyice&snowdamagingtransmissionlines.Inspperformedongovernor&steamtraps.W/910412ltr.DISTRIBUTIONCODE:IE22TCOPIESRECEIVED:LTRENCLSIZE:TITLE:50.73/50.9LicenseeEventReport(LER),ncidentRpt,etc.NOTESRECIPIENTIDCODE/NAMEPD3-1LACOLBURN,T.INTERNAL:ACNWAEOD/DSP/TPABNRR/DET/ECMB9HNRR/DLPQ/LHFB11NRR/DOEA/OEABNRR/DST/SELBSDPLBSD1REIE02ILE01EXTERNALEG&GBRYCEiJ~HNRCPDRNSICMURPHYiGACOPIESLTTRENCL1111221111111111111111331111RECIPIENT'DCODE/NAMEPD3-1PDAEOD/DOAAEOD/ROAB/DSPNRR/DET/EMEB7ENRR/DLPQ/LPEB10NRR/DREP/PRPBllNRR/DST/SICB7ENRR/DST/SRXBSERES/DSIR/EIBLSTLOBBYWARDNSICMAYS,GNUDOCSFULLTXTCOPIESLTTRENCL111122111122111111111111NOTETOALL"RIDS"RECIPIENTSPLEASEHELPUSTOREDUCEiVASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOP,IPI-37(EXT.20079)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLISTSFORDOCUMENTSYOUDON'TNEED!FULLTEXTCONVERSIONREQUIREDTOTALNUMBEROFCOPIESREQUIRED'TTR31ENCL31 IndianaMichigan~PowerCompany~CookNuclearPlarnOneCookPlaceBridgrnan.Ml494066164655901April12,1991lMDIANANICHlGANPOWERUnitedStatesNuclearRegulatoryCommissionDocumentControlDeskRockville,Maryland20852OperatingLicensesDPR-74DocketNo.50-316DocumentControlManager:Inaccordancewiththecriteriaestablishedby10CFR50.73entitledLicenseeEventReortinSstemthefollowingreportisbeingsubmitted:91-004-00Sincerely,vj.oeA.A.BlindPlantManagerAAB:sbAttachmentc:D.H.Williams,Jr.A.B.Davis,RegionIIIE.E.FitzpatrickP.A.BarrettB.F.HendersonR.F.KroegerB.Walters-Ft.'ayneNRCResidentInspectorT.Colburn-NRCJ.G.KepplerM.R.PadgettG.Charnoff,Esq.DottieSherman,ANILibraryD.HahnINPOS.J.Brewer/B.P.LauzauB.A.Svenssone10q13030g910412PDRADOCK05000316PDRgpP NRCFORM366(669)tAPPROVEDOMBNO.3)504))04EXPIRES:4/30/92ESTIMATEDBURDENPERRESPONSETOCOMPLYWTHTHISLICENSEEEVENTREPORTILER)COMMENTSREGARDINGBURDENESTIMATETOTHERECORDSINFORMATIONCOLLECTIONREQUEST:50.0HRS.FORWARDANDREPORTSMANAGEMENTBRANCHIP630),V.S.NUCLEARREGULATORYCOMMISSION,WASHINGTON,DC20555,ANDTOTHEPAPERWORKREDUCTIONPROJECT(31504104),OFFICEOFMANAGEMENTANDBUDGET,WASHINGTON,OC20503.FACILITYNAME(1)D.C.CookNuclearPlant-Unit2DOCKETNUMBER(2)IIAE3ppppp316~pF04~JfeactorProtectionSystemActuationDuetoIceandSnowDamainOff-SiteElectricalTransmissionLines.EVENTDATEIS)LERNUMBER(6)REPORTDATE(7)OTHERFACILITIESINVOLVED(4IMONTHDAYYEARYEARc)P?ISSOVENTIAL?g4NVMSERr'cccREvtclore~a.;NVMSSRMONTHDAYYEARFACILITYNAMESDOCKETNUMBER(SIp5ppp03139'19100400041291p5pppOPERATINGMODE(9)]POWERLEYEL100PO)~~"'P~Mk'"9"~V~c++':*20.402(S)20.405(~)(1)Bl20.405(e)(1)(ii)20A05(el(1)(iii)20A05(e)(I)(iv)20A06(~I(I)(r)20.406(cl50.34(c)(1)50.$6(cl(2)50.73(e)(2)(I)50.7$(e)(2)(ii)50.73(eI(2)(iii)LICENSFECONTACTFORTHISLER(12150,73(~)(2)(iv)50.7$(~)(2)N)"50.73(e)(2)(vS)50.73(e)l2)(riiillAI50.73(~)(2)(vBI)(B)50.73(~)(2)(x)THISREPORTISSUBMITTEDPURSUANT70THERLOUIREMENTSOF10CFR(ItIChechoneotmoreofthefotlowfnf)(1173.71(S)73.71(c)OTHERISpeclfyInAbttrectbelowenrflnText,HRCForm$68AINAMEP.F.Carteaux-SafetyandAssessmentSuperintendentTELEPHONENUMBERAREACODE616465-5901COMPLETEONELINEFOREACHCOMPONENTFAILUREDESCRIBEDINTHISREPORT(13)CAUSESYSTEMCOMPONENTMANUFAC.TURERORTABLTONPRDS9'&Yr.CAUSESYSTEMCOMPONENTMANUFAC.TVREREPORTABLTONPRDS87%&SUPPLEMENTALREPORTEXPECTED(14)YESIlfyet,completeEXPECTEDSVBhtISSIOIIDATEINOABSTRACTILlmlttof400epecet,I.e.,epptoxlmetelyfrfteentingletpecetypewrittenlinn)(16)EXPECTEDSUBMISSIONDATE(15I'H~ohcccivco.k%MONTHDAYYEAROnMarch13,1991at0651hours,theUnit2reactortrippedasaresultofaturbinetripgeneratedbyamoistureseparator-reheater(MSR)highwaterleveltrip.Theturbine-generatortripandreactortripwerearesultofoff-siteelectricaltransmissionsystemdisturbances.Iceandsnowdamaged765KVtransmissionlineswhichcausedasignificantloadrejectiononthemainturbine.TheclosingofthemainturbinecontrolvalvesinresponsetotheloadrejectioncreatedaMSRpressuretransientwhichactuatedtheMSRhighwaterleveltripandtrippedthemainturbineandreactor.TheplantwasstabilizedinMode3.Abnormalitiesnotedduringtheeventincludedtheelectronicoverspeedtripoftheturbinedrivenauxiliaryfeedwaterpump,closureofoneofthefourmainsteamisolationvalves,andapparentslowclosureofthe¹4combinedinterceptvalve.AllequipmentmalfunctionswerereviewedwithnounreviewedsafetyquestionsandthereactorwasreturnedcriticalonMarch15,1991at1113hours.NRCForm366(689)

NRCFORM366A(64)9)U.S.NUCLEARREGULATORYCOMMISSIONLICENSEEEVENTREPORT(LER)TEXTCONTINUATIONAPPROVED0MBNO.31500104EXPIRES:4/30/92ESTIMATEDBURDENPERRESPONSETOCOMPLYWTHTHISINFORMATIONCOLLECTIONREQUEST!50.0HRS.FORWARDCOMMENTSREGARDINGBURDENESTIMATETOTHERECORDSANOREPORTSMANAGEMENTBRANCH(P4)30),U.S.NUCLEARREGULATORYCOMMISSION,WASHINGTON,DC20555,ANDTOTHEPAPERWORKREDUCTIONPROJECT(31504)104),OFFICEOFMANAGEMENTANDBUDGET,WASHINGTON,0020503.FACILITYNAME(1)D.C.CookNuclearPlant-Unit2DOCKETNUMBER(2)LERNUMBER(6)SEQUENTIALW'oRFYISIONNUM88R'OSSNUM88RPAGE(3)TEXT/I/moreepece/4rer/or)ed,oreeddio'one/P/RCForrrr3664'4/(12)osooo31691004-0002QF04ConditionsPriortoOccurrenceUnit2inMode1at100percent,ofRatedThermalPower(RTP).DescritionofEventOnMarch13,1991at0651hours,theUnit2reactor(EIIS/JE)trippedasaresultofaturbine(EIIS/TA)tripgeneratedbyamoistureseparator-reheater(MSR)(EIIS/SB-MSR)highwaterleveltrip.Theturbine-generatortripandreactortripwerearesultofoff-siteelectricaltransmissionsystemdisturbances.Iceandsnowdamaged765KVtransmission(EIIS/FK)lineswhichcausedasignificantloadrejectiononthemainturbine(greaterthan504steamflowwithnoload).Theclosingofthemainturbinecontrolvalves(EIIS/TA-FCV)inresponsetotheloadrejectioncreatedaMoistureSeparator-Reheater(MSR)pressuretransientwhichactuatedtheMSRhighwaterleveltripandtrippedthemainturbineandreactor.ThetimefromthemostsevereelectricaltransienttotheMSRhighleveltripwas11.5seconds.Themainturbinecontrol.system(EIIS/TA-HCU)includesaspeedgovernordrivenbygearsinthefrontstandardandreceivesinputsfromtheload-limiter,operatingdevice,accelerationlimiter,steampressurelimiter,andcontrol,valvepositionfeedback;Theaccelerationlimiter(EIIS/TA-SCO)preventstheturbinefromtrippingonoverspeedonaloadrejectionbyreactingmorequicklythanthegovernorandtherebylimitingthemaximumspeedreachedbytheturbine.Iftheturbineaccelerationreaches47RPMpersecond,correspondingtoa50%loadrejection,the,accelerationlimiterwillclosethehighpressurecontrolvalvesandlowpressureinterceptvalves.IItisbelievedthatthe765KVlinedisturbances,priortotheturbinetrip,causedasignificantloadrejectionandactuatedtheaccelerationlimiter.TheunequalclosingtimesofthecontrolvalvesandinterceptvalvescreatedaMSRpressuretransientwhichliftedtheMSRsafetyvalvesandactuateda5-secondtimedelayedMSRhighleveltrip.Followingtheturbinetrip/reactortripsequence,[tuibine(EIIS/TA-TRB)trip,openingorthereactortripbreakers(EIIS/JE-BKR),insertionofreactorcontrolrods(EIIS/AA-ROD),feedwaterisolation(EIIS/JB),andautomaticstartingofthemotordrivenauxiliaryfeedwaterpumps(EIIS/BA-P)],OperationspersonnelimmediatelyimplementedEmergencyOperatingProcedure2OHP4023.E-O'toverifyproperresponseoftheautomaticprotectionsystemandtoassesplantconditionsforindicatedappropriatedrecoveryactions.NRCForm366A1669)

NRCFORMSeeA(689)U.SNUCLEARREGULATORYCOMMISSIONtLICENSEEEVENTREPORT(LER)'EXTCONTINUATIONAPPROVEDOMBNO.31500104EXPIRES:4/30/92ESTIMATEDBUADENPERRESPONSETOCOMPLYWTHTHISINFOAMATIONCOLLECTIONREOUEST:50.0HRS.FORWARDCOMMENTSREGARDINGBURDENESTIMATETO,THERECORDSANDREPOATSMANAGEMENTBRANCH(P.530),U.S,NUCLEARREGULATORYCOMMISSION,WASHINGTON,OC20555,ANDTOTHEPAPERWORKREDUCTIONPROJECT(31500104).OFFICEOFMANAGEMENTANDBUDGET,WASHINGTON,DC20503.FACILITYNAME(1ID.C.CookNuclearPlant-Unit2DOCKETNUMBER(2)LERNUMBER(6)YEARSPSSEOUSNTIAL@~/IIEVISIONNUM88A'NA:NUM888PAGE(3)TEXT/Ifmom4Pooo/4/oqowod,844oddrdono/HRCFomI36543)(IT)osooo3l691-004-00030F04Followingthemaingeneratortripandtransfertoreservefeed(EIIS/FK),the345KVbusprovidedastablepowersupplyfortheUnit2auxiliaryloads.AreviewoffaultrecordsforUnit1showedsystemupsetstoalesserdegree,asitwasnotdirectlylinkedtothe765KVbus.Abnormalitiesnotedduringtheeventincludedtheelectronicoverspeedtripoftheturbinedrivenauxiliaryfeedwaterpump(EIIS/BA-P),closureofoneofthefourmainsteamisolationvalves(EIIS/SB-ISV),andslowclosureoftheN4combinedinterceptvalve(EIIS/SB-ISV).Theturbinedrivenauxiliaryfeedwaterpumpwasimmediatelyresetandplacedinstandby.Themainsteamisolationvalvewasbel'ievedtohavedriftedshutandwasreopenedwithinminutesofthetrip.TheN4combinedinterceptslowclosurehasbeenattributedtoanindicationproblemandnotvalveinoperability.CauseofEventThecauseoftheeventwasiceandsnowdamaging765KVoff-siteelectricaltransmissionlinesresultinginanelectricaldisturbancebeyondthecontrolcapabilityoftheunit.AnalsisofEventThisreportisbeingsubmittedinaccordancewithl0CFR50.73,paragraph(a)(2)(iv),asaeventthatresultedinanunplannedautomaticactuationoftheEngineeredSafetyFeatures,includingtheReactorProtectionSystem.Theautomatic'rotectionresponses,includingreactortripanditsassociatedactuationswereverifiedtohavefunctionedproperlyasaresultofthereactortripsignal.Theelectronic.overspeedtripoftheTurbineDrivenAuxiliaryfeedwaterpumpwasimmediatelyresetfromthecontrolroomanditisbelievedthat,thepumpwouldhavebeenavailableifrequired.TheMainSteamIsolationValve,whichdriftedshut,wasreopenedwithinminutesofthetrip.Theslowclosureofthecombinedinterceptvalvewasattributedtoalimitswitchwhichdidnotreflectactualvalveposition.Basedontheabove,itisconcludedthattheeventdidnotconstituteanunreviewedsafetyquestionasdefinedin10CFR50.59(a)(2)nordiditadverselyimpactthehealthandsafetyofthepublic.NRCForm366A(669)

NRCFORM366A(689)LICENSEEEVENTREPORT(LER)TEXTCONTINUATION!APPROVED0MBNO.31500104EXPIRES:4/30/92ESTIL(ATEDBURDENPERRESPONSETOCOMPLYWTHTHISINFORMATIONCOLLECTIONREOUESTI50.0HRS.FORWARDCOMMENTSREGARDINGBURDENESTIMATETOTHERECORDSANDREPORTSMANAGEMENTBRANCH(PJ)30),U.S.NUCLEARREGULATORYCOMMISSION,WASHINGTON,DC20555,ANDTOTHEPAPERWORKREDUCTIONPROJECT(31500104),OFFICEOFMANAGEMENTANDBUDGET,WASHINGTON,DC20503.FACILITYNAME(1)DOCKETNUMBER(21LERNUMBER(6)PAGE(3)D.C.CookNuclearPlant-Unit2TEXT/lfmomSOooo/4mqoksd,ooooddi)looo/HRCFono36649/(17)CorrectivectionsYEARi?(gosooo31691SEOVENTIAI.?.'o?NUMBER'Fc?I004REVISIONNUMBER0004OF04TurbineDrivenAuxiliaryFeedwaterPump(TDAFP)ThecauseoftheTDAFPelectronicoverspeedtripcouldnotbeconclusivelydetermined.Athroughreviewoftheeventandextensivetestingdidnotrevealthereasonfortheoverspeedevent.Posttriptestingincluded:omeasurement'ftheasfoundelectricaltripoinspectionofthegovernorvalvelinkageandstemforbindingorcorrosionoinspectionofthegovernoroilforwatercontaminationoinspectionofsteamtrapsonthesteamsupplypipingoafunctionaltestoftheTDAFPelectronicoverspeed.Alltestsandinspectionswerenormal.MainSteamIsolationValve(MSIV)ClosingAreviewofpastUnit1andUnit2tripsshowedseveralcaseswhereMSIVsdriftedofftheiropenseats,aswasthecaseonthisparticulartripwithMSIVs421and422.ThiswasthefirsttripidentifiedwhereaMSIVclosedcompletely,butgiventhesecondarytransientexperienced,itisnotconsideredunusualthatthiswouldoccur.CombinedInterceptValve44TheCombinedInterceptValve44appearedtoslowcloseovera5minuteperiodasindicatedbyanintermediatevalvepositionandthefactthattheTurbineEventsRecorderdidnotregisterthevalveasbeingclosed.Asaconditiontorestart,thevalvewastimedinthecloseddirectionandyieldedavalueof1.2seconds.'tisbelievedthatasinglelimitswitchdidnotinitiallyclose.ThislimitswitchwouldkeeptheopenlightlitandpreventtheTurbineEventsRecorderformindicatingaclosedposition.FailedComonentIdentificationNonePreviousSimilarEventsNoneNRCFoim366A(BS9)