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

REGULAYINFORMATION DISTRIBUTIYSTEM(RIDS).ACCESSION NBR:8710230216 DOC.DATE:87/10/19NOTARIZED:

NOFACIL50-389St.LuciePlantrUnit2FloridaPoujerCcLightCo.AUTH.NAMEA'UTHORAFFILIATION WOQDYrC.O.FloridaPowerhLightCo.RECIP.NAMERECIPIENT AFFILIATION DOCKETir05000389

SUBJECT:

Specialrept:on870902rGeneralMotorsemergency dieselgenerator Sailedtostart.Causedbg12cylinderengineactuatorF'riction clutchassemblyoutoPadJustment.

ClutchassemblyadJusted.

W/871019ltr.DISTRIBUTION CODE;IE22DCOPIESRECEIVEDLTRiENCL[SIZE;TITLE:50.73LicenseeEventReport(LER)iIncidentRptretc.NOTES:RECIPIENT IDCODE/NAME PD2-2LATOURIGNYIECOPIESLTTRENCL1111RECIPIENT

.COPIESIDCODE/NAME LTTRENCLPD2-2PD'11INTERNAL:

ACRSMICHELSON

.AEOD/DOAAEOD/DSP/ROAB ARM/DCTS/DAB NRR/DEST/ADS NRR/DEST/ELB NRR/DEST/MEB NRR/DEST/PSB NRR/DEST/SGB NRR/DLPG/GAB NRR/DREP/RAB NS/SIB~EGFILE'02RESTELFORDrJRGN2FILE01EXTERNAL:

EGSGQROHIMLPDRNSICHARRIS'111221101111111111111111551111ACRSMOELLERAEOD/DSP/NAS AEOD/DSP/TPAB DEDRONRR/DEST/CEB NRR/DEST/

ICSBNRR/DEST/MTB NRR/DEST/RSB NRR/DLPG/HFB NRR/DOEA/EAB NRR/DREP/RPB NRR/PMAS/

ILRB.RESDEPYGIRES/DE/EIB HSTLOBBYWARDNRCPDRNSICMAYSrG221111111111111122'11'11111111TOTALNUMBEROFCOPIESREQUIRED:

LTTR45ENCL44 P.OX14000,JUNOBEACH,PL334080420OCTOBER1g1987L-87-4I8U.S.NuclearRegulatory Commission Attn:DocumentControlDeskWashington, D.C.20555Gentlemen:

Re:St.LucieUnit2DocketNo.50-389DateofEvent:September 2,l987SecialReortonDieselGenerator FailureTheattachedSpecialReportisbeingtransmitted pursuanttotherequirements ofTechnical Specification 4.8.I.I.3 and6.9.Itoprovidenotification ofthe2AEmergency DieselGenerator failure.Verytrulyyours,C.O.WGroupVicePresident NuclearEnergyCOW/GRM/gp Attachment cc:Dr.~.'Nelson Grace,RegionalAdministrator, RegionII,USNRCSeniorResidentInspector, USNRC,St.LuciePlant87i02302ib 87iOi9PDRADOCK05000389SGRM2/034/IanFPLGroupcompany SPECIALREPORTDIESELGENERATOR FAILURE~~At0920hoursonSeptember 2,l987,St.LucieUnit2Emergency DieselGenerator (EDG)2Awasstartedforasurveillance run.Analarmwasreceivedwhichindicated thatoneoftheenginesinthe2AEDGhadfailedt'ostart.Theinputsignaltothisalarmisahightemperature differential betweenthel6andthel2cylinderengines'urbo exhausttemperatures indicating thattheenginewiththehottestexhaustispickingupmoreloadthantheotherengine.ThetwoEDG'sinstalled inSt.LucieUnit2areGeneralMotorsEMD645-E4units,eachconsisting ofal6cylinderandal2'cylinder enginemountedintandemanddrivingasinglegenerator.

Atthetimethe2AEDGwasstarted,aplantoperatorobservedlocallythattheleverforthel2cylinderenginefuelracksdidnotmove.Theleverindicator forthefuelrackisgraduated from62tol96,withthel96positionbeingintheidlepositionand62beingthefullyrackedinposition.

Asobservedbytheoperatorduringtheinitalstart,-theleverwasattheI96positionuntilapproximately oneminuteafterstartingwhe'ntheleverpositionwasnotedtobeapproximately atthel30position.

Itwasalsoobservedbytheoperatorthatthetemperature differential betweentheengines'urbo exhaustwasapproximately 280degreesF.Thel2cylinderenginetemperature wasl50degreesFandthel6cylinderenginewasat430degreesF.Whenthel2cylinderenginestarted,the12cylinderenginetemperature rose,andthealarmcleared.At0922,the2AEDGwasstopped.Thereactorcontroloperatornotedthestartingtimetobel2seconds,thisexceededtheTechnical Specification requiredtimeofIOsecondsorless.At.0938,the2AEDGwasre-started toallowoperations personnel toassessandevaluateitsperformance.

Thesta'rttimewas7.76secondsandnoapparentproblemwiththefuelrackswasnoted.The2AEDG.wasthenstoppedtoallowcooldowninpreparation fortheperformance oftherequiredsurveillance run'tl245,the2AEDGwasre-started forthesurveillance run.Thestarttimewasnotedtobe8.52seconds.Atl350,the2AEDGwasstoppedandthesurveillance runwasdeemedsatisfactory.

Althoughthesubsequent re-starts ofthe2AEDGindicated thatthe2AEDGstartedandaccelerated toatleast900rpmandreachedtherequiredvoltageandfrequency inlessthanIOseconds,theinitialstartwasdetermined tobeavaliddieselfailure.Thisdetermination wasbasedonthefollowing:

(I)theexcessive startingtime,(2)theindication thattheleverforthel2cylinderenginefuelracksdidnotmoveinuntilapproximately oneminuteafterstarting, and(3)theobservedhightemperature differential betweenthel6andthel2cylinderengines'urbo exhausttemperatures.'he lastEDGfailurewasinJuly9,l986.ThisisthefirstfailureofaSt.LucieUnit2Emergency DieselGenerator withinthe'lastl00validstarts.Thesurveillance frequency remainsasonceper3Idays,whichisIriconformance withregulatory positionC.2.dofRegulatory GuideI.I08,RevisionI,AugustI977.GRM2/034/2 On'September 22,l987,theEDGtaskteamsupported byelectical maintenance,'echanical maintenance andoperations personnel performed testsandinspections onthe2AEDGtodetermined therootcauseofthefailure.Astructure treewasdeveloped an'dfromitarecommended test/inspection wasgenerated.

Thetestrevealedthatthel2cylinderengineactuatorfrictionclutchassemblywasoutofadjustment by0.5inch-pounds.

(Therecommended range.ofadjustment is4.5to5.5inch-pounds)

Theasfoundtorquewas4.0inch-,pounds.

Thefrictionclutchwasreadjusted to4.5inch-pounds andthentheact'uator wasrestoredtonormal.The~2AEDGwasreturnedtooperations forsurveillance testing,experienced anormalstartsequenceandstartedin6.99seconds.Theenginesloadednormally.

TheEDGtaskteamconcluded thatitispossiblethattheslippageinthisassemblycouldproduceintermittent problemswiththestartsequence.

Aperiodiccheckofthefrictionclutchadjustment hasbeenaddedtotheEDGmaintenance program.Anotherpotential itemofconcernwasthegovernorairboosterassembly.

TheairboosterassemblywillbesenttoWoodwardGovernorfortestingandevaluation forwear/degradation, andareportwillbeprovidedtotheSt.LuciePlantontheirfindings.

ThiswillbedoneduringtheupcomingSt.LucieUnit2refueling outageinOctoberl987.GRM2/034/3

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