ML17221A454

Special Rept:On 870902,General Motors Emergency Diesel Generator Failed to Start.Caused by 12-cylinder Engine Actuator Friction Clutch Assembly Out of Adjustment.Clutch Assembly Adjusted

ML17221A454
Person / Time
Site:	Saint Lucie
Issue date:	10/19/1987
From:	WOODY C O FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
L-87-418, NUDOCS 8710230216
Download: ML17221A454 (5)

Text

REGULAYINFORMATIONDISTRIBUTIYSTEM(RIDS).ACCESSIONNBR:8710230216DOC.DATE:87/10/19NOTARIZED:NOFACIL50-389St.LuciePlantrUnit2FloridaPoujerCcLightCo.AUTH.NAMEA'UTHORAFFILIATIONWOQDYrC.O.FloridaPowerhLightCo.RECIP.NAMERECIPIENTAFFILIATIONDOCKETir05000389

SUBJECT:

Specialrept:on870902rGeneralMotorsemergencydieselgeneratorSailedtostart.Causedbg12cylinderengineactuatorF'rictionclutchassemblyoutoPadJustment.ClutchassemblyadJusted.W/871019ltr.DISTRIBUTIONCODE;IE22DCOPIESRECEIVEDLTRiENCL[SIZE;TITLE:50.73LicenseeEventReport(LER)iIncidentRptretc.NOTES:RECIPIENTIDCODE/NAMEPD2-2LATOURIGNYIECOPIESLTTRENCL1111RECIPIENT.COPIESIDCODE/NAMELTTRENCLPD2-2PD'11INTERNAL:ACRSMICHELSON.AEOD/DOAAEOD/DSP/ROABARM/DCTS/DABNRR/DEST/ADSNRR/DEST/ELBNRR/DEST/MEBNRR/DEST/PSBNRR/DEST/SGBNRR/DLPG/GABNRR/DREP/RABNS/SIB~EGFILE'02RESTELFORDrJRGN2FILE01EXTERNAL:EGSGQROHIMLPDRNSICHARRIS'111221101111111111111111551111ACRSMOELLERAEOD/DSP/NASAEOD/DSP/TPABDEDRONRR/DEST/CEBNRR/DEST/ICSBNRR/DEST/MTBNRR/DEST/RSBNRR/DLPG/HFBNRR/DOEA/EABNRR/DREP/RPBNRR/PMAS/ILRB.RESDEPYGIRES/DE/EIBHSTLOBBYWARDNRCPDRNSICMAYSrG221111111111111122'11'11111111TOTALNUMBEROFCOPIESREQUIRED:LTTR45ENCL44 P.OX14000,JUNOBEACH,PL334080420OCTOBER1g1987L-87-4I8U.S.NuclearRegulatoryCommissionAttn:DocumentControlDeskWashington,D.C.20555Gentlemen:Re:St.LucieUnit2DocketNo.50-389DateofEvent:September2,l987SecialReortonDieselGeneratorFailureTheattachedSpecialReportisbeingtransmittedpursuanttotherequirementsofTechnicalSpecification4.8.I.I.3and6.9.Itoprovidenotificationofthe2AEmergencyDieselGeneratorfailure.Verytrulyyours,C.O.WGroupVicePresidentNuclearEnergyCOW/GRM/gpAttachmentcc:Dr.~.'NelsonGrace,RegionalAdministrator,RegionII,USNRCSeniorResidentInspector,USNRC,St.LuciePlant87i02302ib87iOi9PDRADOCK05000389SGRM2/034/IanFPLGroupcompany SPECIALREPORTDIESELGENERATORFAILURE~~At0920hoursonSeptember2,l987,St.LucieUnit2EmergencyDieselGenerator(EDG)2Awasstartedforasurveillancerun.Analarmwasreceivedwhichindicatedthatoneoftheenginesinthe2AEDGhadfailedt'ostart.Theinputsignaltothisalarmisahightemperaturedifferentialbetweenthel6andthel2cylinderengines'urboexhausttemperaturesindicatingthattheenginewiththehottestexhaustispickingupmoreloadthantheotherengine.ThetwoEDG'sinstalledinSt.LucieUnit2areGeneralMotorsEMD645-E4units,eachconsistingofal6cylinderandal2'cylinderenginemountedintandemanddrivingasinglegenerator.Atthetimethe2AEDGwasstarted,aplantoperatorobservedlocallythattheleverforthel2cylinderenginefuelracksdidnotmove.Theleverindicatorforthefuelrackisgraduatedfrom62tol96,withthel96positionbeingintheidlepositionand62beingthefullyrackedinposition.Asobservedbytheoperatorduringtheinitalstart,-theleverwasattheI96positionuntilapproximatelyoneminuteafterstartingwhe'ntheleverpositionwasnotedtobeapproximatelyatthel30position.Itwasalsoobservedbytheoperatorthatthetemperaturedifferentialbetweentheengines'urboexhaustwasapproximately280degreesF.Thel2cylinderenginetemperaturewasl50degreesFandthel6cylinderenginewasat430degreesF.Whenthel2cylinderenginestarted,the12cylinderenginetemperaturerose,andthealarmcleared.At0922,the2AEDGwasstopped.Thereactorcontroloperatornotedthestartingtimetobel2seconds,thisexceededtheTechnicalSpecificationrequiredtimeofIOsecondsorless.At.0938,the2AEDGwasre-startedtoallowoperationspersonneltoassessandevaluateitsperformance.Thesta'rttimewas7.76secondsandnoapparentproblemwiththefuelrackswasnoted.The2AEDG.wasthenstoppedtoallowcooldowninpreparationfortheperformanceoftherequiredsurveillancerun'tl245,the2AEDGwasre-startedforthesurveillancerun.Thestarttimewasnotedtobe8.52seconds.Atl350,the2AEDGwasstoppedandthesurveillancerunwasdeemedsatisfactory.Althoughthesubsequentre-startsofthe2AEDGindicatedthatthe2AEDGstartedandacceleratedtoatleast900rpmandreachedtherequiredvoltageandfrequencyinlessthanIOseconds,theinitialstartwasdeterminedtobeavaliddieselfailure.Thisdeterminationwasbasedonthefollowing:(I)theexcessivestartingtime,(2)theindicationthattheleverforthel2cylinderenginefuelracksdidnotmoveinuntilapproximatelyoneminuteafterstarting,and(3)theobservedhightemperaturedifferentialbetweenthel6andthel2cylinderengines'urboexhausttemperatures.'helastEDGfailurewasinJuly9,l986.ThisisthefirstfailureofaSt.LucieUnit2EmergencyDieselGeneratorwithinthe'lastl00validstarts.Thesurveillancefrequencyremainsasonceper3Idays,whichisIriconformancewithregulatorypositionC.2.dofRegulatoryGuideI.I08,RevisionI,AugustI977.GRM2/034/2 On'September22,l987,theEDGtaskteamsupportedbyelecticalmaintenance,'echanicalmaintenanceandoperationspersonnelperformedtestsandinspectionsonthe2AEDGtodeterminedtherootcauseofthefailure.Astructuretreewasdevelopedan'dfromitarecommendedtest/inspectionwasgenerated.Thetestrevealedthatthel2cylinderengineactuatorfrictionclutchassemblywasoutofadjustmentby0.5inch-pounds.(Therecommendedrange.ofadjustmentis4.5to5.5inch-pounds)Theasfoundtorquewas4.0inch-,pounds.Thefrictionclutchwasreadjustedto4.5inch-poundsandthentheact'uatorwasrestoredtonormal.The~2AEDGwasreturnedtooperationsforsurveillancetesting,experiencedanormalstartsequenceandstartedin6.99seconds.Theenginesloadednormally.TheEDGtaskteamconcludedthatitispossiblethattheslippageinthisassemblycouldproduceintermittentproblemswiththestartsequence.AperiodiccheckofthefrictionclutchadjustmenthasbeenaddedtotheEDGmaintenanceprogram.Anotherpotentialitemofconcernwasthegovernorairboosterassembly.TheairboosterassemblywillbesenttoWoodwardGovernorfortestingandevaluationforwear/degradation,andareportwillbeprovidedtotheSt.LuciePlantontheirfindings.ThiswillbedoneduringtheupcomingSt.LucieUnit2refuelingoutageinOctoberl987.GRM2/034/3

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