ML17223A162

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Special Rept:On 890406,emergency Diesel Generator 2A Failed. Caused by Thrust Bearing Failure Due to Excessive Clearance Between Bearing Collar & Fan Shaft.Cooling Fan Blades & Shroud Repaired
ML17223A162
Person / Time
Site: Saint Lucie NextEra Energy icon.png
Issue date: 06/05/1989
From: WOODY C O
FLORIDA POWER & LIGHT CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-89-185, NUDOCS 8906090135
Download: ML17223A162 (3)


Text

ACCELEP~TEDDlBI'TIO~DEMONSTPQTIOYSYSTEMDOCKET05000389

SUBJECT:

Specialrept:on890406,2Aemergencydieselgeneratorfailure.DISTRIBUTIONCODE:IE22DCOPIESRECEIVED:LTRENCLSIZE:TITLE:50.73/50.9LicenseeEventReport(LER),ncidentRpt,etc.NOTES:(2)fREGULATORYINFORMATIONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:8906090135DOC.DATE:89/06/05NOTARIZED:NOFACIL:50-389St.LuciePlant,Unit2,FloridaPower&LightCo.AUTH.NAMEAUTHORAFFILIATIONWOODY,C.O.FloridaPower&LightCo.RECIP..NAMERECIPIENTAFFILIATIONDocumentControlBranch(Document.ControlDesk)RECIPIENTIDCODE/NAMEPD2-2LANORRIS,JINTERNAL:ACRSMICHELSONACRSWYLIEAEOD/DSP/TPABDEDRONRR/DEST/ADE8HNRR/DEST/CEB8HNRR/DEST/ICSB7NRR/DEST/MTB9HNRR/DEST/RSB8ENRR/DLPQ/HFB10NRR/DOEA/EAB11NUDOCS-ABSTRACTRES/DSIR/EIBRGN2FILE01COPIESLTTRENCL11111111111'111111,111111111111111RECIPIENTIDCODE/NAMEPD2-2PDACRSMOELLERAEOD/DOAAEOD/ROAB/DSPIRM/DCTS/DABNRR/DEST/ADS7ENRR/DEST/ESB8DNRR/DEST/MEB9HNRR/DEST/PSB8DNRR/DEST/SGB8DNRR/DLPQ/PEB10FRPB10EGFIL02RSR/PRABCOPIESLTTRENCL1122112211101111111111221111hEXTERNALEG&GWILLIAMSgS44LSTLOBBYWARD11NRCPDR11NSICMURPHY'~A11FORDBLDGHOY~A11LPDR11NSICMAYS,G11IDNCTEK)ALL"RIDS"RECIPIENTSPLEASEHELPUS'IOiKDUCEWASTE!CXWZACZ'IHEDOCUMEhl7CGVZROLDESK,RXNPl-37(EXP.20079)%0EZJ2GXATEVCRNAMEPBCHDIBTEGBUTIGN-LISTSFORDOCUMENZSYOUDGN~TNEEDtTOTALNUMBEROFCOPIESREQUIRED:LTTR43ENCL429DS P.O.Box14000,JunoBeach,FL334080420JUNE51989L-89-185U.S.NuclearRegulatoryCommissionAttn:DocumentControlDeskWashington,D.C.20555Gentlemen:Re:St.LucieUnit2DocketNo.50-389DateofEvent:April6,1989SecialReortonDieselGeneratorFailureTheattachedSpecialReportisbeingtransmittedpursuanttotherequirementsofTechnicalSpecification4.8.1.1.3toprovidenotificationofa2AEmergencyDieselGeneratorfailure.Verytrulyyours,C~>.C.O.~~oodyActingSenior-VicePresident-NuclearCOW/GRJ1/gpAttachmentcc:StewartD.Ebneter,RegionalAdministrator,RegionII,USNRCSeniorResidentInspector,USNRC,St.LuciePlant8~0<0901,=-:589060(PDj@DOCK0":000=%'DC SPECIALREPORTDIESELGENERATORFAILURES2ADIESELGENERATORFAILURE:InaccordancewithNRCRegulatoryGuide1.108,SectionC.2.e,thiseventisconsideredtobeavaliddieselgeneratorfailure.At1640onApril6,1989,the2Adiesel(D/G)wasstartedandloadedforaonehoursurveillancerunbeforedeclaringtheD/Gbackinserviceaftermaintenance.Approximately55minutesintotherun,autilityoperatorstationedattheD/Gnoticedsparkscomingfromthesouthcoolingfanduetocontactwithitsshroudhousingonthe16cylinderengine.TheD/Gwasimmediatelystopped.Thecauseofthecoolingfanaxialdisplacementandcontactagainstitsshroudwasduetoathrustbearingfailureonthefanshaft.Therootcauseofthethrustbearingfailurewasduetoexcessiveclearancebetweenthebearingcollarandthefanshaft.Thesmallclearancemeasuredwassufficienttopermitmovementbetweenthebearingcollarandthefanshaftwhichleadtofatiguefailureof.thecollar.Thebearingcollarisheldontotheshaftwithsetscrews.Thedesigntolerancewasneverspecifiedinanyplantdrawing,andthereforewasnotconsideredcriticalorrequiredtobemeasured.Thefailureofthe2AD/Gwasthethirdfailureinthepast100validtests.Thecurrent2AD/Gtestfrequencyisonceper31days'hefollowingcorrectiveactionswereimplemented:1)Thecoolingfanbladesandshroudwererepaired.2)Thethrustbearingwasreplacedandthenewclearancebetweentheshaftandbearingcollarwasdeterminedtobesatisfactorybythebearingmanufacturer.3)OtherD/Gfanshaftbearingssusceptibletothisfailuremechanismwereinspectedonboththe2Aand2BD/G's.Atotalof40bearingswereinspectedwhichincludedfanshaft,idlershaft,anddriveshaftbearings.Fivethrustbearingsandtwofloatingbearingswerereplaced.MaintenanceprocedureswillberevisedtorequireperiodicinspectionoftheD/Gfanshaftbearings".4)Thesouthfanonthe2A12cylinderenginewasfoundtohaveadamagedshaftduetoexcessiveshafttocollarclearance.Anewfanshaftwasmanufacturedforthe2AD/Gandinstalledwithsatisfactoryshafttobearingcollarclearance.Asimilarconditionwasfoundonafandriveshaftforthe2BD/G.Anewshaftwasmanufacturedandinstalledonthe2BD/G.5)Asurveillancerunwasperformedandthe2AD/GwasdeclaredbackinserviceonApril11,1989.