ML18024A056

Susquehanna Units 1 and 2 - Letter Supplementing Pp&L Letters Dated April 17, 1978 and July 14, 1978 and Attaching a Final Report of a Deficiency in Seismic Qualification of Medium Voltage, Metal Clad, Safeguards Switchgear

ML18024A056
Person / Time
Site:	Susquehanna
Issue date:	09/15/1978
From:	Curtis N W Pennsylvania Power & Light Co
To:	Grier B H NRC Region 1
References
Download: ML18024A056 (12)

Text

REGULATORYINFORMATIONDISTRIBUTIONSYSTEM(BIDS>DISTRIBUTIONFORINCOMINGMATERIAL50-387REC:GRIER8HNRCORG:CURTISNWPAPNR5LIGI-lTDOCDATE:09/15/78DATERCVD:09/22/78DOCTYPE:LETTERNOTARIZED:NOCOPIESRECEIVED

SUBJECT:

LTR1ENCLFURNISHINGSUPPLEMENTTOAPPLICANT"SLTRSOF04/17/73AND07/14/78CONTAININGFINALCONSTRUCTIONDEFICIENCYREPTCONCERNINGDEFICIENCYINEISMICQUALIFICATIONOFMEDIUMVOLTAGEM.TALCLADSAFEGUARDSWITCHGEAR.PLANTNAME:SUSQUEHANNA"<<UNIT1uv%%%%%%%%%%%%%%%DISTRIBUTIONOFTHISMATERIALNOTES:SENDIS(E3CYSFSAR8(ALLAMDTGCONSTRUCTIONDEFICIENCYREPORT<10CFR50.55E)(DISTRIBUTIONCODE8019>REVIEWERINITIAL:XJMDISTRIBUT0BINITIAL~IGASFOLLOWS%%<%%%%%%%%%%%%%%%FORACTION:INTERNAL:EXTERNAL:ASSTDIRVASSALL0%%W/ENCLPRMINER%%W/ENCL.6FILE%%/ENCL0ENCL,GOScSICKRcSTAFF%%W/ENCLDIRECTORDPM%%W/ENCLQAB%%W/ENCLADFORENG%kW/ENCLADFORPLANTSYSTEMS%%W/ENCLSTANDARDSDEV.%%W/ENCLFERDDREHER/IE%%W/ENCLLPDRSNILKESBARREiPA%%M/ENCLTERA<<%W/ENCLNSIC%%W/ENCLACRSCATB%%W/16ENCLBRCI.IIEFLWR03BC%%W/ENCLLICASSTLWR83LA<<W/ENCLNRCPDR%%W/ENCLOELDu~W/ENCLMIPC%%W/ENCLDEPUTYDIRDPM%%W/ENCLDIRECTORDSS%%W/ENCLADFORREACSFTY%%W/ENCLADFORSYS8(PROJ%%W/ENCLKSEYFRIT/IE%%W/ENCLCONTROLNBR:780860147At~THEEND

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~g~"~~;-),$)I)~~.(gPg~XKDsesTWONORTHNINTHSTREET,ALLENTOWN,PA.18101/g$ITJNE:(215)821-5151NORMANW,CURTISVicePresidentEngineering8Construction821-5381SeptEmber15,1978Mr.BoyceH.GrierDirector,RegionIU.S.NuclearRegulatoryCczanission631ParkAvenueKingofPrussia,Pennsylvania17406CJo>Irrc's'nv>+mCnrnCllPl<onaP1~CDC)SUSQUEEQKASTEAMELECTRICSTATIONF3'EPORTOFADEFICIENT',CYINSEISMICQUAIZFICATIONOFI%DENVOLTAGE,M'TALCLAD,SM."%GUARDSSWITCHGFARDOCKETNO.:50-387LICENSENO:CPPR-101ER100450FILE840-4PLA289'~=I~4\I

DearMr.Grier:

ThissupplementsPPSZlettersPLA-246,datedApril17,1978andPLA-271,datedJuly14,1978,andprovidesafinalreportofthesubjectdeficiencyasrecpuzedby10CFR50.55(e).Pleaseadviseshouldyourecureadditionalinformation.Verytrulyyours,N.W.CurtisVicePresident-Engineering6ConstructionAttachmentARS:mcbcc:Mr.J.G.Davis(15)ActingDirector-OfficeofInspection6EnforcementU.S.NuclearReyQatoryCcmiission--Washington,D.C.20555Mr.G.MDonald,Director(1)OfficeofManaganent,,Information6~amContxol'U.S.NuclearRegulatoryCcmtissionWashington,D.C.20555PENNSYLVANIAPOWER8,LIGHTCOMPANYt78p86p1479'e~t

'Mr.B.H.GrierSept.anber15,1978cc:Mr.RobertM.GalloU.S.NuclearRegulatoryGmxnissionP.O.Box52Shickshinny,Pennsylvania18655 OFADEFICIENCYINSEISMICQUALIFICATIONOFMEDIUMVOLTAGE,MEALCLAD,SAFEGUABDSSWHCHG1RRFORTHESUSQUEHANNASTEAM1KZCTRICSTATICND.P.ParsonsSSESElectricalGroupSupvr.ApprovedBy:..~~~9r~pg.A.M.eSupervisingEngineer-Design-SuscpehannaReviewed:A.R.ScilManager-NuclearQualityAssurancePENNSYLVANIAHMK6LIGHTCCMPANYAL'EZKTQWN,PENNSYLVANIAS1M.'EMBER15,1978 TABLEOFCONTENTSIntroductionDescriptionofDeficiencyAnalysisofSafetyImplicationsCorrectiveActionConclusionPg.lPgs,lg2g3Pg.3Pgs.4,5Pg.5 INTRODUCZIONThisreportispreparedinaccordancewiththerequirementsdescribedinTitle10,CodeofFederalRegulations,Part50,Section50.55(e).PPKwasadvised,throughitsA/E(Bechtel)organization,t1wtWestinghousesupplied,mediumvoltage,metalcladswitchgearwasnotcapableofwithstandingthepostulatedseismiceventforSusquehannaPlant.BechtelwasrequestedtoreviewthesituationandadvisePPsZofitsfindings.OnParch31,1978theNRCwasinformedthatadeficiency,potentiallyreportableunder10CFR50.55(e),wasbeingevaluated,andonApril17,1978,followinganengineeringreview,PALissueditsInterimReportofthedeficiency.Thedeficiencywasdeterminedtobereportableunder10CFR50.55(e)forthefollowingreasons:1.Thedeficiency,wereittoremainuncorrected,couldhaveresultedinasafetyhazardtotheoperationoftheplant.2.Thedeficiencyrepresentedadeficiencyinfinaldesignasapprovedandreleasedforfabricationandinstallation.3.Eightsafety-relatedswitchgearunitshad,beenshippedandacceptedforinstallationbeforethedeficiencywasdiscovered.DJHCRIPTIONOFDEFICIENCYTheSusquehannaPlantwassuppliedeightdeficientsafetyrelatedmediumvoltageswitchgearunitsbyWestinghouse.Fouroftheseswitchgearunitssupplypowerdirectlyto4kvsafetyrelatedequipnent,pumprmtorsandloadcenters,>RichareusedtomitigatetheeffectsofanaccidentinUnitl.

Likewise,fourswitchgearunitsareusedasthesupplyfor4kvsafetyrelatedloadsonUnit2.Eachswitchgearunit,containsthreepotentialtransformercircuits,oneofthecircuitsconsistsof~potentialtransformersconnectedinanopendelta.Theothertwocircuitseachcontainonepotentialtransformerusedtosensesinglephasepotential.Thepotentialtransformersareusedtoobtain120volt,potentialirr3icationforusewithrelaysontheswitchgearunits'heIIediumVoltageYwtalCladSwitchgear(Safeguards)Specification(8856-E-109)requirestheequipmenttomeetseismicrecpdxementsofProjectSpecification8856-6-10,IEEEStandardM.344,andtoreaeinfunctional,koth,duringandafteranOBEorDBE.WestinghouseadvisedBechtelonJanuary24,1978thatthepotentialtransformersecondarydisconnectingcontactassanbliesonequignentsimilartothatsuppliedforSusquehannahadfailedtowithstandrecentseismictests.Westinghousefurtherstatedthat,underseismicconditions,itispossiblethattheslip-fitsecondarycontactscouldbedislodgedfrantheirnormalpositionsresultinginopenor.shortcircuitingofthesecondarycircuits.WestinghouserequestedthatBechtelevaluatetheconditiontodetaanineifitauldconstituteasafetyhazard..Westinghouseconfirmedthattherewerenofailuresofpotentialtransformercircuitsduringtheoriginalseismicqualificationtests.However,thesecircuitsweresubsequent1yredesignedandthenewdesignwasanalyticallyqualified.Situalseismictestsonswitchgearunitsincorporatingthenewdesignresultedinthepotentialtransformercircuitfailures>M.charethesubjectofthisreport.

Westinghousealsoconfirmedthattheseianicqualificationofallothercanponentsintheseassembliesremainvalid.MALYSISOFSMOKYIMPLICATIONSTheengineeringevaluationdeterminedthattheopenorshortcircuitingofanyoftheseco~contactscouldresult.inincorrectoperationofaswitchgearunit.Itwasconcludedthattheworstconditionresultsfranthelossofallthreepotentialtransformercircuitsoneachswitchgearbus.Underthiscondition,thetminccmingbusfeedersfrcmthesafeguardtransformers(onefromeachoffsitesource)wouldbeautomaticallydisconnectedfrcmeachswitchgearbusandthedieselgeneratorpowersourceconnectedrestoringpowertothebus.ALOCAoccuringduringorafterthepostulated,seismiceventwouldinitiateaclosingsignaltothemotorfeederbreakersoftheshutdownloads,i.e.RHRandCoreSprayHotors.ThesefeederbreakerswouldcloseandismMiatelytripduetothefalseundervoltageindicationassensedbytheundervoltagerelay.Thecircuitbreakerswouldbeunabletocloseagainbecauseofthepermanentundervoltagetripsignalimposedonthem.Theaboveanalysisassumes'hat,thefailuresconcurrentlyoccuronallredundantm~tchgearhuses.BasedupontheevaluationofBechtelEngineering~itisconcludedthatthisconditionofnotbeingabletosupplypowertotheshutdownloadsunderaDXKconditionconstitutesasafetyhazardtotheoperationoftheplantandrepresentsadeficiencyinfinaldesign.

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CORRECTIVE'ACTIONActionTakentoContxol'Deficient.'ItemsTheactionstakenbyBechtelpriortothesuhnittaloftheinterimreportofthedeficiencybyPP&LaredomunentedinPZA-246datedApril17,1978.Inadditiontothemeasurespreviouslyidentified,andintheinterestofobtainingdocumentedevidenceofBechtelPxojectEngineering'sevaluationofthecondition'scause,correctiveactionrequired,andreportabilityunder10CFR50.55(e),BechtelQAgeneratedIhnagerrentCorrectiveActionRequestNo.1-22datedMarch28,1978.CorrectiveActionto'Control'Resolution'of'theDeficienciesWestinghousehassuppliedmodificationkitswhichprovideforeliminatingthestationaxy,secondarydisconnectingcontactassembliesfromthepotentialtransformercircuits.Twenty-four(24)(threekitsforeachoftheeightsafety-relatedswitchgearunits)potentialtransfoxmersecondaryfieMrmdificationkits(WestinghouseStyleNo.628F14G01)havebeenprovided.TheserrodificationkitshavebeeninstalledbyBechtelfieldelectricianspertheinstructionsonWestinghousedrawing628F146.ThesechangesweremadeunderthesupervisionoftheWestinghouseEngineeringServicePersonnel.Themodificationconsistsofhardwiringthesecondaryarablecontacttoatexminalblockviaawiringharness.ThePTsecondarycircuitsarethenconnectedtothefieldsideoftheterminalblock.Thesecondarystationarycontactsareremovedentirely,thuseliminatingthesourceoftheseismicfailure.

~~I(~Westinghousehasseianicallyqualifiedthepotentialtransformerswiththe@edifiedsecondarycontactarrangement.DonznentedevidenceofthisqualificationhasbeenprovidedtoBechtelthrougharevisiontotheoriginalqualificationreport.COVZIJSXONSl4xlificationshavebeenmadetoaU.theWestinghousesafety-related,medianvoltageswitchgearunitscontainingpotentialtransformersandpurchasedunderP.O.8856-E-109ACforSusquehannaSteamElectricStation.TheBechtelgeneratedhMnconfoxmanceReport(NCRhM.2514)willnotbeclosedoutuntilBechtelQualityContxolhasperformedtheattendantinspectionsandhasverifiedthatthemxlificationkitsrareinstalledaccordingtodesignrequirements-Theandifiedswitchgearunitsarequalifiedtomeetthepostulatedseismicevent.forSusquehannaanddocumentationofthisseismicqualificationhasbeenreceivedandwillbereviewedbyBechtelEngineering.Bechtel'sacceptanceofthisdocumentationwillresultinanacceptablydocumentedrevisiontotheWestinghouseSeianicQualificationReport.Theswitchgearunits~aspresentlymodified,arecompatiblewithpurchaseorder,PSARandFSARrequiranents.