ML17228A917

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
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.ERATED RlDSI'ROC!:.SSIX REGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:.9411300214 DOC~DATE:94/11/23NOTARIZED:

NOFACIL:50-335 St.LuciePlant,Unit1,FloridaPower&LightCo.AUTH.NAMEAUTHORAFFILIATION SAGER,D.A.

FloridaPower&LightCo.RECIP.NAME RECIPIENT AFFILIATION DocumentControlBranch(Document ControlDesk)

SUBJECT:

Specialrept:on941028,EDG failureoccurredduetoburnedthroughwirefrommagneticamplifier terminalblocktofield.Wirerepaired&relandedtoterminalblock.DISTRIBUTION CODE:IE22DCOPIESRECEIVED:LTR

!ENCLLSIZE:9TITLE:50.73/50.9 LicenseeEventReport(LER),TncidentRpt,etc.NOTESDOCKET05000335RECIPIENT IDCODE/NAME PD2-2PDINTERNAL'CRS AEOD/SPD/RRABNRR/DE/EELB NRR/DORS/OEAB NRR/DRCH/HICB NRR/DRSS/PRPB NRR/DSSA/SRXB RES/DSIR/EIB EXTERNAL:

LSTLOBBYWARDNOACMURPHY,G.A NRCPDRCOPIESLTTRENCL1111'1111111221111111111RECIPIENT IDCODE/NAME NORRIS,JA.EOD%~OAB/~S PECN~R>02NRR/DE/EMEB NRR/DRCH/HHFB NRR/DRCH/HOLB NRR/DSSA/SPLB NRR/PMAS/IRCB-E RGN2FILE01LITCOBRYCE,JHNOACPOORE,W.NUDOCSFULLTXTCOPIESLTTRENCL112211111111111111221111EMOTETOALL"RlDS"RECIPIENTS:

PLE:XSEfkELPL'STOREDL'CEiVKSTE!COi'fhC'f'I'IIEDOC!:iIEiT COifROI.DESk.ROOXIPl-37(EXT.504-2083)TOELIilliAI'E5'OI.'RiAi!LZFI<OilDISTRI8L'TION LISI'SFORDOCI.'iII:.i'I'S YOU'Oi'"I'l ED!TOTALNUMBEROFCOPIESREQUIRED:

LTTR27ENCL27 FloridaPower8tLightCompany,P.O.Box128,FortPierce,FL34954.0128 November23,1994L-94-29410CFR50.36U.S.NuclearRegulatory Commission Attn:DocumentControlDeskWashington, DC20555Re:St.LucieUnit1DocketNo.50-335SpecialReportDateofEvent:October28,1994EmerencDieselGenerator Failure,TheattachedSpecialReportisbeingsubmitted pursuanttotherequirements oftheSt.LucieTechnical Specifications.

Thisreportprovidesnotification ofonevalidfailureofthe1BDieselGenerator.

Shouldtherebeanyquestions onthisinformation, pleasecontactus~Verytrulyyours,Qg~/gD.A.SerVicePidentSt.LuiPlantDAS/msdAttachment cc:StewartD.Ebneter,RegionalAdministrator, USNRCRegionIISeniorResidentXnspector, USNRC,St.LuciePlant~rq(1"t="-411300214 941123PDRADOCK050003i5SPORanFPLGroupcon>panyP(pwI)

I.TITLEValidFailureofthe1BEmergency DieselGenerator duetoaBurnedThroughWirefromtheMagneticAmplifier TerminalBlocktotheField.II.INITIALCONDITIONS St.LucieUnit1wasinMode5atthestartofarefueling outageandSt.LucieUnit2wasat100%power.III.EVENTSEQUENCEOn10/28/94withUnit1inarefueling outage,plantpersonnel commenced Operating Procedure 1-0400050,

.At1758,aLossofOffsitePower(LOOP)wasinitiated aspartoftheprocedure andthe1Aand1BEmergency DieselGenerators (EDG)startedandloaded.At1858the1BEDGsuccessfully completed theLoadRejection partoftheprocedure.

Continuing withtheprocedure the1Aand1BEDGbreakerswereopenedandthe1Aand1BEDGswerestoppedlocallyat2205withtheemergency stoppushbuttons.

At2208aLOOPwasagaininitiated aspartoftheprocedure andthe1Aand1BEDGsstartedandloaded.Offsitepowerwasrestoredat2235andthe1Aand1BEDGsloadwasreducedto500KW.At2257autilitylicensedReactorOperatorintheUnit1controlroomsaw1BEDGmegavarspeggedlow(reactive loadinthelead)andloadincreasing.

TheSeniorNuclearPlantOperator(SNPO)atthe1BEDGreportedsmellingsmokeandlocallystoppedthe1BEDGwiththeemergency stoppushbutton.

IV.CAUSEOFTHEEVENTInvestigation byElectrical Maintenance (EM)revealedaburnedwireatamagneticamplifier (mag-amp) terminalblock.Themag-ampprovidestheselfexcitation voltagetothe1BEDGfieldwinding.Alooseconnection hadcausedoverheating andtherewasdamagetothewireanditsinsulation.

Thelooseconnection waspossiblyduetotheuseofstrandedwireinacompression fitting.Duetoresistance heatinglossesthewireburnedintwocausinganerroneous voltagetothe1BEDGfieldexcitation whichresultedinalossofregulator control.Thiswasavalidtest/valid failureasitwasterminated duetoanalarmedabnormalcondition thatwouldhaveultimately resultedinanEDGfailure.

V.CORRECTIVE ACTIONS1.The1BEDGwasemergency trippedbytheSNPOafterhesmelledsmoke.2.EMpersonnel repairedtheaffectedwireandrelandedittotheterminalblock.3.EMpersonnel meggeredthefieldcurrentcircuit,themag-ampcoilsandthe1BEDGwindingswithsatisfactory results.4.EMpersonnel inspected the1BEDGterminalblocksforsimilarlooseconnections withsatisfactory results.5.EMpersonnel performed theeighteenmonthsurveillance onthe1AEDGwhichincludescheckingforlooseconnections.

6.Operations performed asurveillance runofthe1BEDGanddeclareditbackinservice.7.Unit2EDGsdonothavethesametypeofterminalblockduetoadifferent vendor,butwillbeinspected duringtheupcomingeighteenmonthsurveillance.

8.FPLSiteEngineering isevaluating thestrandedwire/compression fittinginterface.

VI.SUPPORTING INFORMATION

-Thiswasthefirstvalidfailureofthe1BEDGintheprevioustwentyvalidtestsandthesixthvalidfailureinthepreviouseighty-nine starts(EDGruncountsbegan6/12/90whenRegGuide1.108wasimplemented intotheSt.LucieUnit1Technical Specifications).

Thecurrentnumberofvalidtestsforthe1BEDGisnowninety-one.

-The1BEDGwasoutofserviceforapproximately fourteenhoursuntiltherepaircouldbecompleted andasuccessful surveillance testwasperformed.

-Duetothefailure,the1BEDGisrequiredtobesurveilled everysevendaysuntilsevenconsecutive failurefreetestsareachievedperTechnical Specification 3.8.1.1,Table4.8-1.