ML17228A917

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Special Rept:On 941028,EDG Failure Occurred Due to Burned Through Wire from Magnetic Amplifier Terminal Block to Field.Wire Repaired & Relanded to Terminal Block
ML17228A917
Person / Time
Site: Saint Lucie NextEra Energy icon.png
Issue date: 11/23/1994
From: SAGER D A
FLORIDA POWER & LIGHT CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-94-294, NUDOCS 9411300214
Download: ML17228A917 (4)


Text

J.%AMMAAIA(:ECCEI.ERATEDRlDSI'ROC!:.SSIXREGULATORYINFORMATIONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:.9411300214DOC~DATE:94/11/23NOTARIZED:NOFACIL:50-335St.LuciePlant,Unit1,FloridaPower&LightCo.AUTH.NAMEAUTHORAFFILIATIONSAGER,D.A.FloridaPower&LightCo.RECIP.NAMERECIPIENTAFFILIATIONDocumentControlBranch(DocumentControlDesk)

SUBJECT:

Specialrept:on941028,EDGfailureoccurredduetoburnedthroughwirefrommagneticamplifierterminalblocktofield.Wirerepaired&relandedtoterminalblock.DISTRIBUTIONCODE:IE22DCOPIESRECEIVED:LTR!ENCLLSIZE:9TITLE:50.73/50.9LicenseeEventReport(LER),TncidentRpt,etc.NOTESDOCKET05000335RECIPIENTIDCODE/NAMEPD2-2PDINTERNAL'CRSAEOD/SPD/RRABNRR/DE/EELBNRR/DORS/OEABNRR/DRCH/HICBNRR/DRSS/PRPBNRR/DSSA/SRXBRES/DSIR/EIBEXTERNAL:LSTLOBBYWARDNOACMURPHY,G.ANRCPDRCOPIESLTTRENCL1111'1111111221111111111RECIPIENTIDCODE/NAMENORRIS,JA.EOD%~OAB/~SPECN~R>02NRR/DE/EMEBNRR/DRCH/HHFBNRR/DRCH/HOLBNRR/DSSA/SPLBNRR/PMAS/IRCB-ERGN2FILE01LITCOBRYCE,JHNOACPOORE,W.NUDOCSFULLTXTCOPIESLTTRENCL112211111111111111221111EMOTETOALL"RlDS"RECIPIENTS:PLE:XSEfkELPL'STOREDL'CEiVKSTE!COi'fhC'f'I'IIEDOC!:iIEiTCOifROI.DESk.ROOXIPl-37(EXT.504-2083)TOELIilliAI'E5'OI.'RiAi!LZFI<OilDISTRI8L'TIONLISI'SFORDOCI.'iII:.i'I'SYOU'Oi'"I'lED!TOTALNUMBEROFCOPIESREQUIRED:LTTR27ENCL27 FloridaPower8tLightCompany,P.O.Box128,FortPierce,FL34954.0128November23,1994L-94-29410CFR50.36U.S.NuclearRegulatoryCommissionAttn:DocumentControlDeskWashington,DC20555Re:St.LucieUnit1DocketNo.50-335SpecialReportDateofEvent:October28,1994EmerencDieselGeneratorFailure,TheattachedSpecialReportisbeingsubmittedpursuanttotherequirementsoftheSt.LucieTechnicalSpecifications.Thisreportprovidesnotificationofonevalidfailureofthe1BDieselGenerator.Shouldtherebeanyquestionsonthisinformation,pleasecontactus~Verytrulyyours,Qg~/gD.A.SerVicePidentSt.LuiPlantDAS/msdAttachmentcc:StewartD.Ebneter,RegionalAdministrator,USNRCRegionIISeniorResidentXnspector,USNRC,St.LuciePlant~rq(1"t="-411300214941123PDRADOCK050003i5SPORanFPLGroupcon>panyP(pwI)

I.TITLEValidFailureofthe1BEmergencyDieselGeneratorduetoaBurnedThroughWirefromtheMagneticAmplifierTerminalBlocktotheField.II.INITIALCONDITIONSSt.LucieUnit1wasinMode5atthestartofarefuelingoutageandSt.LucieUnit2wasat100%power.III.EVENTSEQUENCEOn10/28/94withUnit1inarefuelingoutage,plantpersonnelcommencedOperatingProcedure1-0400050,.At1758,aLossofOffsitePower(LOOP)wasinitiatedaspartoftheprocedureandthe1Aand1BEmergencyDieselGenerators(EDG)startedandloaded.At1858the1BEDGsuccessfullycompletedtheLoadRejectionpartoftheprocedure.Continuingwiththeprocedurethe1Aand1BEDGbreakerswereopenedandthe1Aand1BEDGswerestoppedlocallyat2205withtheemergencystoppushbuttons.At2208aLOOPwasagaininitiatedaspartoftheprocedureandthe1Aand1BEDGsstartedandloaded.Offsitepowerwasrestoredat2235andthe1Aand1BEDGsloadwasreducedto500KW.At2257autilitylicensedReactorOperatorintheUnit1controlroomsaw1BEDGmegavarspeggedlow(reactiveloadinthelead)andloadincreasing.TheSeniorNuclearPlantOperator(SNPO)atthe1BEDGreportedsmellingsmokeandlocallystoppedthe1BEDGwiththeemergencystoppushbutton.IV.CAUSEOFTHEEVENTInvestigationbyElectricalMaintenance(EM)revealedaburnedwireatamagneticamplifier(mag-amp)terminalblock.Themag-ampprovidestheselfexcitationvoltagetothe1BEDGfieldwinding.Alooseconnectionhadcausedoverheatingandtherewasdamagetothewireanditsinsulation.Thelooseconnectionwaspossiblyduetotheuseofstrandedwireinacompressionfitting.Duetoresistanceheatinglossesthewireburnedintwocausinganerroneousvoltagetothe1BEDGfieldexcitationwhichresultedinalossofregulatorcontrol.Thiswasavalidtest/validfailureasitwasterminatedduetoanalarmedabnormalconditionthatwouldhaveultimatelyresultedinanEDGfailure.

V.CORRECTIVEACTIONS1.The1BEDGwasemergencytrippedbytheSNPOafterhesmelledsmoke.2.EMpersonnelrepairedtheaffectedwireandrelandedittotheterminalblock.3.EMpersonnelmeggeredthefieldcurrentcircuit,themag-ampcoilsandthe1BEDGwindingswithsatisfactoryresults.4.EMpersonnelinspectedthe1BEDGterminalblocksforsimilarlooseconnectionswithsatisfactoryresults.5.EMpersonnelperformedtheeighteenmonthsurveillanceonthe1AEDGwhichincludescheckingforlooseconnections.6.Operationsperformedasurveillancerunofthe1BEDGanddeclareditbackinservice.7.Unit2EDGsdonothavethesametypeofterminalblockduetoadifferentvendor,butwillbeinspectedduringtheupcomingeighteenmonthsurveillance.8.FPLSiteEngineeringisevaluatingthestrandedwire/compressionfittinginterface.VI.SUPPORTINGINFORMATION-Thiswasthefirstvalidfailureofthe1BEDGintheprevioustwentyvalidtestsandthesixthvalidfailureinthepreviouseighty-ninestarts(EDGruncountsbegan6/12/90whenRegGuide1.108wasimplementedintotheSt.LucieUnit1TechnicalSpecifications).Thecurrentnumberofvalidtestsforthe1BEDGisnowninety-one.-The1BEDGwasoutofserviceforapproximatelyfourteenhoursuntiltherepaircouldbecompletedandasuccessfulsurveillancetestwasperformed.-Duetothefailure,the1BEDGisrequiredtobesurveilledeverysevendaysuntilsevenconsecutivefailurefreetestsareachievedperTechnicalSpecification3.8.1.1,Table4.8-1.