ML17223B168

Special Rept:On 910320,1B Emergency Diesel Generator (DG) Nonvalid Failure Occurred Due to Circuitry Failure of DG Synchronizing Circuitry.Relay Exhibiting Binding Calibr & Will Be Replaced

ML17223B168
Person / Time
Site:	Saint Lucie
Issue date:	04/17/1991
From:	SAGER D A FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-91-122, NUDOCS 9104240135
Download: ML17223B168 (3)

Text

ACCELERATEDDISUTIONDEMONSTRATIONSYSTEMtrREGULATORYINFORMATXONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:9104240135DOC.DATE:91/04/17NOTARIZED:NOFACIL:50-335St.LuciePlant,Unit.1,FloridaPower6LightCo.AUTH.NAMEAUTHORAFFILIATXONSAGER,D.A.FloridaPowerSLightCo.RECIP.NAMERECIPIENTAFFXLIATIONDocumentControlBranch(DocumentControlDesk)

SUBJECT:

Specialrept:on910320,1Bemergencydieselgeneratornon-validduringsurveillancetesting.Sysprotectiontestedrelayelectriclly6foundoperable&plamsavailabletoreplaceengineeringdedication.W/910417ltr.DISTRIBUTIONCODE:ROOIDCOPIESRECEIVED:LTR)ENCLISIZE:TITLE:ORSubmittal:GeneralDistributionNOTES:DOCKET05000335RDARECIPIENTIDCODE/NAMEPD2-2LANORRIS,JXNTERNAL:ACRSNRR/DET/ESGBNRR/DSTSE2NRR/DST/SICB7ENUDOCS-ABSTRACTOGC/HDS3RES/DSXR/EIBEXTERNAL:NRCPDRCOPIESLTTRENCL11226611111111101111RECIPIENTIDCODE/NAMEPD2-2PDNRR/DET/ECMB9HNRR/DOEA/OTSB11NRR/DST/SELBSDNRR/DST/SRXB8EOCKEFXLEOlNSICCOPIESLTTRENCL1111111111101111DDRDNOTETOALL"RIDS"RECIPIENTS:PLEASEHELPUSTOREDUCEWASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMP1-37(EXT.20079)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLISTSFORDOCUMENTSYOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED:LTTR24ENCL22DD P.O.Box,Ft.Pierce,FL34954-0128April17,1991L-91-12210CFR50.36U.SNuclearRegulatoryCommissionAttn:DocumentControlDeskWashington,DC20555Gentlemen:Re:St.LucieUnit1DocketNo.50-335SpecialReportDateofEvent:March20,1991EmerencDieselGeneratorFailureTheattachedSpecialReportisbeingtransmittedpursuanttotherequirementsofSt.LucieUnit1TechnicalSpecifications4.8.1.1.3and6.9.2.Thereportprovidesnotificationofa1BEmergencyDieselGeneratornon-validfailureduringsurveillancetesting.Shouldtherebeanyquestionsonthisinformation,pleasecontactuseVerytrulyyours,D.A.VicegersidentSt.LuciePlantDAS:GRM:kwDAS/PSL5416Attachmentcc:StewartD.Ebneter,RegionalAdministrator,RegionII,USNRCSeniorResidentInspector,USNRC,St.LuciePlant9104240135910417PDRADOCK05000335SPDRP,$~,g~9QnFPLGroupcompany NRCSPECIALREPORTDIESELGENERATORNON-VALIDFAILUREAt0904onMarch20,1991,theSt.LucieUnitOne1BEmergencyDieselGeneratorwasstartedforitsmonthlysurveillancerun.Severalattemptsweremadetosynchronizethedieselgeneratorontothegrid;however,theD/Goutputbreakerwouldnotclose.ElectricalMaintenancewascalledintotroubleshootthesynchronizingcircuitry,andthe1Bdieselgeneratorwasshutdownanddeclaredoutofserviceat0947.CorrectiveActions:ElectricalMaintenancePersonneldeterminedthattheD/Gsynchronizingrelaywasmalfunctioning.SystemProtectionpersonneltestedtherelayelectricallyandfoundittobeoperable.However,mechanicalmanipulationofthecontactarmscausedbinding.Acalibrationoftherelaywasperformedanditwasnotedthattherelayexhibitedintermittentbindingofthecontacts.Noreplacementrelayswereavailableatthetimeofthisfailure.Plansareinplacetoreplacetherelayfollowinganengineeringdedicationofareplacement,andPC/Mpackage.The1Bdieselgeneratorwasrestartedat1248andtheoutputbreakerwasclosedat1255.Thesurveillancewassuccessfullycompletedat1407andthedieselwasdeclaredbackinservice.Thedieselwasdeclaredoutofserviceforatotalof4hoursand20minutes.Theproblemwasevaluatedtobeanon-validfailureperRegulatoryGuide1~108C.2.e.2,inthattheaffectedcircuitrywastheD/Gsynchronizingcircuitry.Thiscircuitryisusedforsurveillancepurposesonly,whenthedieselmustbetiedontothelivebus.DuringaLossofOffsitePowerevent,thiscircuitryisbypassedandtheD/Gwillautomaticallypickuptheplantsafetybus.Atnotimeduringthiseventwasthedieselgeneratorunabletoperformitsintendedsafetyfunction.FailureSummary:WiththerecentincorporationofamendmentstoTechnicalSpecification3.8.1.1(July1990),therehavebeennorecordedvalidfailuresofthe1BEmergencyDieselGeneratorandnine(9)successfulstarts.Thesurveillancefrequencyremainsonceper31daysasperTechSpec3.8.1.1.