ML17157A220

Rev 1 to SEA-EE-226, Evaluation of Welded Shut Class 1E Limitorque Limit Switches Used for Unit 2 Computer Inputs.

ML17157A220
Person / Time
Site:	Susquehanna
Issue date:	05/03/1990
From:	ARUS J P PENNSYLVANIA POWER & LIGHT CO.
To:
Shared Package
ML17157A218	List: ML17157A217 ML17157A219 ML17157A220 ML17157A221 ML17157A222 ML18030A072
References
SEA-EE-226, SEA-EE-226-R01, SEA-EE-226-R1, NUDOCS 9006290165
Download: ML17157A220 (12)

Text

QwjwII~~ENGINEERINGSTUDIES,ANALYSES,ANDEVALUATIONSCOVERSHEETOIAI.ITYI.EYEI.AFETYASIDERTIIEDIIOIINAI.ITYED/CTIIND,.SEAIIODcrIID.FADEIOF4yEVALUATIONOFWELDEDSHUTCLASS1ELIMITORQUELIMITSWITCHESUSEDFORUNIT2COMPUTERINP9006290165900619PDRADOCK05000337PPDCOI3ogo,peak~Ill+/y~REVISIONNO.DATEPREPAREDBYI'IoREVIEIEDBYPPROVEDB IEI~'ILA")

SEA-EE-226Page2of6EVALUATIONOFWELDEDSHUTCLASS1ELIMITORQUELIHITSWITCHESUSEDFORUNIT2COMPUTERINPUTS1.0SCOPEThepurposeofthisSEAistoevaluatetheimpactofaweldedshutlimitswitchfromClasslELimitorquemotoroperatorsontheoperationoftheClass1Evalve.SEA-EE-183determinedthatclosedLimitorquecomputerinputlimitswitchescouldweldshutforimpressedvoltagefaults.

2.0CONCLUSION

SANDRECOMMENDATIONS

2.1CONCLUSION

SAnalysisoftheUnit2ClasslEmotor-operatedvalvesshowsthatthesevalves,exceptforMainSteamLineDrainIsolationValvesHV-821-2F016andHV-821-2F019andtheReactorWaterCleanupIsolationValvesHV-G33-2F001andHV-G33-2F004,willmeettheirminimumperformancerequirementsevenifthecomputerinputlimitswitchesshouldweldshut.Thisconclusionisbaseduponanevaluationthatshows:--Thevalveschangepositionandmeettheirminimumperformancerequirementsbeforethecomputerinputlimitswitchesareexposedtopotentialcontactwelding,i.e.thevalvelimitswitchesarenormallyopenandtheyclosewhenthevalvechangespositiontoitsisolationposition.OR-Thevalvesareinaffiliated(associated)circuitsandcontactsfromthesedevicesarenotusedinClass1Ecircuits,i.e.operationofthevalveisnotrequiredfordesignbasiseventconditions.IntheeventcomputerinputlimitswitchesforHV-G33-2F001,HV-G33-2F004,HV-821-2F016andHV-821-2F019weldshut,thelimitswitchmaindriveshaftscouldperhapsbreaklooseinternaltothevalvescausingthevalvestojam,thuspotentiallypreventingfull.closureofthevalves.Morethanlikelytheweldedshutlimitswitcheswouldcausedamagetothelimitswitchgearing,butwouldnotpreventthesubjectvalvesfromclosing.2.2RECOMMENDATIONToassurethattheHV-G33-2F001,HV-G33-2F004,HV-821-2F016andHV-821-1F019valvesmeettheirminimumperformancerequirementswithimpressedvoltagefaultsontheircomputerinputcables,thecomputerinputlimitswitchesshouldberewiredsuchthatthesevalveschangepositionandmeettheirminimumperformancerequirementsbeforethecomputerinputswitchesareexposedtopotentialwelding.The C.~I~0pi.IA1" SEA-EE-226Page3of6rewiredvalvelimitswitchesshouldbenormallyopenandclosedonlywhenthevalvesare100%closed(i.e.switchclosedwhenthevalvesclosedintheprimarycontainmentisolationposition).ThisactionisbeingtrackedbyNCR87-0021.InordertoprecludetheneedforfutureengineeringanalysisandmaintaincompliancewithRegulatoryGuide1.75,gualifiedElectricalIsolators,capableofwithstanding120VACand250VDC,shouldbeinstalledfornewlyengineereddigitalcomputerinputsdevelopedfromClass1ELimitorquelimitswitches.Thisrecommendationisin-linewithNPE-ElectricalGroupstrategyofeliminatingpotentialpitfallsformaintainingcompliancetotheplantlicensingcommitments.3.0INPUTSANDASSUMPTIONS3.1INPUTSAtSusquehannaSES,computerinputcircuitsarenon-class1EeventhoughtheseinputsaredevelopedfromClass1Emotor-operatedvalves.RegulatoryGuide1.75whichendorsesIEEE384-1974allowstheconnectionoftheselow-energynon-class1EcircuitstoClass1EdevicesprovidedananalysishasbeenperformedtodemonstratethattheClass1Ecircuitsarenotdegradedbelowanacceptablelevelforfaultsonthenon-class1Ecircuits.Computercablesareroutedinnon-classlEracewayswhichalsocontain120VAC,125VDCand250VDCcables.Potentialdamagetocablesinnon-class1Eracewaysmaycauseaccidentalimpositionof120voltsACor250voltsDConcomputerinputwire(s),andthroughthesewirestotheClass1Edevice(s).AsdiscussedinSEA-EE-183,opencontactsofLimitorquelimitswitchescanwithstandimpressedvoltagesof120VACand250VDCacrossthecontacts.However,if120VACor250VDCwereimpressedonclosedcontactsofthelimitswitches,thecontactscouldweldshutifsufficientcurrentflowedforasufficientduration.3.2ThisstudyislimitedtoUnit2digitalcomputerinputsdevelopedfromClass1ELimitorquemotor-operators.ASSUMPTIONSThestudywasbasedonas-builtdrawingsandthedocumentsissuedasofthedateoftaskinitiation.AffiliatedcircuitsinthisstudyweretreatedthesameasClassIEcircuits.Achangeinstateofacomputerinputcontactwhilethereisanimpressedvoltagewasnotconsidered.Onlythecontactintheopenorclosedpositionwasanalyzed.

L\'I~Il~c)~hY K~j~~1SEA-EE-226Page4of64.0METHODSTheSusquehannaSESUnit2I/OSpecificationListing-DigitalRealwasreviewedtoidentifythecomputerinputsdevelopedfromLimitorquemotor-operatorsequippedwithLimitorquelimitswitches.TheSusquehannaSESMotor-OperatorValve(MOV)IndexdatedOctober17,1989andsystemdrawingswerereviewedtodeterminewhichMOVsaresafety-relatedClass1Evalves.Evaluationoftheimpactofwelded-shutLimitorquelimitswitchesusedforcomputerinputswasperformedtoassurethatthesedevicescanperformtheirsafety-relatedfunctionswithweldedcomputerinputlimitswitches.5.0RESULTSReviewoftheSusquehannaSESUnit2I/OSpecificationListingrevealedthatthenumberofcomputerpointsderivedfromClass1ELimitorquelimitswitchesis40.Evaluationofweldedcontactsforeachoftheselimitswitchesisprovided.TheClass1ELimitorquelimitswitchesarepartofmotor-operatedvalveswhichareinoneofthefollowinggroups:l.Affiliated.2.Requirenoautomaticoperation.3.Requireautomaticclosure.Theaffiliatedmotor-operatedvalves,listedinTableI,arepoweredfromClass1Esources.However,thesevalvesandtheirlimitswitchesarenotusedinClass1Ecircuits.Operationofthesevalvesisnotrequiredfordesignbasiseventconditions.Therefore,weldingacomputerinputlimitswitchdoesnoteffectClass1Ecircuits.TheClass1Emotor-operatedvalveswhichrequirenoautomaticoperationarelistedinTable2.Thesevalveshaveopenlimitswitchesforcomputerinputsduringnormalplantlineup.Theselimitswitchesarenotexposedtopotentialwelding.Intheeventthenormalplantlineupischanged,thevalveschangetotheirnewpositionsbeforethecomputerinputlimitswitchesareexposedtopotentialwelding.Therefore,weldingofthecomputerinputlimitswitchesdoesnotpreventthemotor-operatedvalvesfrommeetingtheirminimumperformancerequirements.rInadditiontothevalvesinTable2,theFeedwaterInletStopCheckValvesHV-821-2F032AandHV-821-2F0328motoroperators,whichareintheopenpositionduringnormalplantoperation,arenotrequiredtoautomaticallyoperatefordesignbaseaccidents.However,thesemotoroperatorshaveclosedlimitswitchesforcomputerinputsduringnormalplantoperation.TheFeedwaterInletStopCheckValvesaremotorassistedinordertoprovidethesevalveswithclosingcapability.forprimarycontainmentisolationleakageratetesting.Intheeventthelimitswitchesweldshut,theFeedwaterInletStopCheckValveswillnotbe

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SEA-EE-226Page5of6preventedfromclosingfordesignbaseaccidentssincethesevalvesarecheckvalves.Therefore,theweldingofthecomputerinputlimitswitchesdoesnotpreventHV-B21-2F032AandHV-B21-2F032Bfrommeetingtheirminimumperformancerequirements.TheClass1Evalveswhicharerequiredtooperatefordesignbaseaccidentsareevaluatedbelow:TheESWDiesel"E"CoolerSupplyValvesNos.HV-01110EandHV-01120EarerequiredtoautomaticallycloseforcertainDBA'swhentheDieselGenerator"E"isnotalignedandisbeingtested.Forthiscondition,thecomputerinputlimitswitchesareopenandarenotexposedtopotentialwelding.Ifthesevalvesreceiveanautomaticclosesignal,thevalvechangespositionbeforethecomputerinputlimitswitchesareexposedtopotentialwelding.Therefore,theweldingofthesecomputerinputlimitswitchesdoesnotpreventHV-01110EandHV-01120Efrommeetingtheirminimumperformancerequirements.TheReactorWaterCleanupIsolationValvesHV-G33-2F001andHV-G33-2F004andtheMainSteamLineDrainIsolationValvesHV-B21-2F016andHV-B21-2F019arerequiredtoautomaticallycloseforcertainDBA's.However,thecomputerinputlimitswitchesfromthesevalvesareclosedwhenthesevaivesareopen.Intheeventthecomputerinputlimitswitchesweldshut,thelimitswitchmaindriveshaftscouldperhapsbreaklooseinternaltothevalvescausingthevalvestojam,thuspotentiallypreventingfullclosureofthevalves.PerDanWarsingofLimitorqueCorp.,thisisveryunlikely.Morethanlikely,theweldedshutlimitswitchwillcausedamagetothelimitswitchgearing,butwillnotpreventthevalvesfromclosing.ToassurethattheHV-G33-2F001,HV-G33-2F004,HV-B21-2F016andHV-B21-2F019valvesmeettheirminimumperformancerequirementswithimpressedvoltagefaultsontheircomputerinputcables,thecomputerinputlimitswitchesshouldberewiredsuchthatthesevalveschangepositionsandmeettheirminimumperformancerequirementsbeforethecomputerinputswitchesareexposedtopotentialwelding.Therewiredvalvelimitswitchesshouldbenormallyopenandclosedonlywhen'thevalvesare100%closed(i.e.switchclosedwhenthevalvesclosedintheprimarycontainmentisolationposition).ThisactionisbeingtrackedbyNCR87-0021.REFERENCES6.1IEEE279-1971.6.2IEEE384-1974.6.3RegulatoryGuide1.75,Rev.0.6.4SusquehannaSESUnit2I/OSpecificationListingdated'ec.8,1989.6.5SusquehannaSESMotor-OperatorValveIndexdatedOct.17,1989.6.6SEA-EE-183,Rev.0.6.7SusquehannaSESDesignDescriptionManualChapter5,15and31.jpa/rpa042i(18)

~~Iv SEA-EE-226Page6of6TABLE1AFFILIATEDMOTOR-OPERATEDVALVESHY-821-2F001HV-821-2F002HV-821-2F005HV-831-2F023AHV-831-2F0238HV-831-2F031AHV-831-2F0318HV-831-2F032AHV-831-2F0328TABLE2MOTOR-OPERATEDVALVESNOAUTOMATICOPERATIONHV-01112AHV-011128HV-01112CHV-01112DHV-01110AHV-011108HV-01110CHV-011100HV-01122AHV-011228HV-01122CHV-01122DHV-01120AHV-011208HV-01120CHV-011200HV-01112EHV-01122EHV-821-2F020HV-G33-2F042HV-G33-2F104HV-24182AHV-241828jpa/rpa042i(18) r~~~~~<<f>>4