ML17157A220

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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  Talen Energy icon.png
Issue date: 05/03/1990
From: ARUS J P
PENNSYLVANIA POWER & LIGHT CO.
To:
Shared Package
ML17157A218 List:
References
SEA-EE-226, SEA-EE-226-R01, SEA-EE-226-R1, NUDOCS 9006290165
Download: ML17157A220 (12)


Text

QwjwII~~ENGINEERING STUDIES,ANALYSES, ANDEVALUATIONS COVERSHEET OIAI.ITYI.EYEI.AFETYASIDERTIIEDIIOIINAI.ITYED/CTIIND,.SEAIIODcrIID.FADEIOF4yEVALUATION OFWELDEDSHUTCLASS1ELIMITORQUE LIMITSWITCHESUSEDFORUNIT2COMPUTERINP9006290165 900619PDRADOCK05000337PPDCOI3ogo,peak~Ill+/y~REVISIONNO.DATEPREPAREDBYI'IoREVIEIEDBYPPROVEDB IEI~'ILA")

SEA-EE-226 Page2of6EVALUATION OFWELDEDSHUTCLASS1ELIMITORQUE LIHITSWITCHESUSEDFORUNIT2COMPUTERINPUTS1.0SCOPEThepurposeofthisSEAistoevaluatetheimpactofaweldedshutlimitswitchfromClasslELimitorque motoroperators ontheoperation oftheClass1Evalve.SEA-EE-183 determined thatclosedLimitorque computerinputlimitswitchescouldweldshutforimpressed voltagefaults.

2.0CONCLUSION

S ANDRECOMMENDATIONS

2.1CONCLUSION

S AnalysisoftheUnit2ClasslEmotor-operated valvesshowsthatthesevalves,exceptforMainSteamLineDrainIsolation ValvesHV-821-2F016 andHV-821-2F019 andtheReactorWaterCleanupIsolation ValvesHV-G33-2F001 andHV-G33-2F004, willmeettheirminimumperformance requirements evenifthecomputerinputlimitswitchesshouldweldshut.Thisconclusion isbaseduponanevaluation thatshows:--Thevalveschangepositionandmeettheirminimumperformance requirements beforethecomputerinputlimitswitchesareexposedtopotential contactwelding,i.e.thevalvelimitswitchesarenormallyopenandtheyclosewhenthevalvechangespositiontoitsisolation position.

OR-Thevalvesareinaffiliated (associated) circuitsandcontactsfromthesedevicesarenotusedinClass1Ecircuits, i.e.operation ofthevalveisnotrequiredfordesignbasiseventconditions.

IntheeventcomputerinputlimitswitchesforHV-G33-2F001, HV-G33-2F004, HV-821-2F016 andHV-821-2F019 weldshut,thelimitswitchmaindriveshaftscouldperhapsbreaklooseinternaltothevalvescausingthevalvestojam,thuspotentially preventing full.closureofthevalves.Morethanlikelytheweldedshutlimitswitcheswouldcausedamagetothelimitswitchgearing,butwouldnotpreventthesubjectvalvesfromclosing.2.2RECOMMENDATION ToassurethattheHV-G33-2F001, HV-G33-2F004, HV-821-2F016 andHV-821-1F019 valvesmeettheirminimumperformance requirements withimpressed voltagefaultsontheircomputerinputcables,thecomputerinputlimitswitchesshouldberewiredsuchthatthesevalveschangepositionandmeettheirminimumperformance requirements beforethecomputerinputswitchesareexposedtopotential welding.The C.~I~0pi.IA1" SEA-EE-226 Page3of6rewiredvalvelimitswitchesshouldbenormallyopenandclosedonlywhenthevalvesare100%closed(i.e.switchclosedwhenthevalvesclosedintheprimarycontainment isolation position).

ThisactionisbeingtrackedbyNCR87-0021.Inordertoprecludetheneedforfutureengineering analysisandmaintaincompliance withRegulatory Guide1.75,gualified Electrical Isolators, capableofwithstanding 120VACand250VDC,shouldbeinstalled fornewlyengineered digitalcomputerinputsdeveloped fromClass1ELimitorque limitswitches.

Thisrecommendation isin-linewithNPE-Electrical Groupstrategyofeliminating potential pitfallsformaintaining compliance totheplantlicensing commitments.

3.0 INPUTSANDASSUMPTIONS

3.1INPUTSAtSusquehanna SES,computerinputcircuitsarenon-class 1Eeventhoughtheseinputsaredeveloped fromClass1Emotor-operated valves.Regulatory Guide1.75whichendorsesIEEE384-1974allowstheconnection oftheselow-energy non-class 1EcircuitstoClass1Edevicesprovidedananalysishasbeenperformed todemonstrate thattheClass1Ecircuitsarenotdegradedbelowanacceptable levelforfaultsonthenon-class 1Ecircuits.

Computercablesareroutedinnon-class lEracewayswhichalsocontain120VAC,125VDCand250VDCcables.Potential damagetocablesinnon-class 1Eracewaysmaycauseaccidental imposition of120voltsACor250voltsDConcomputerinputwire(s),andthroughthesewirestotheClass1Edevice(s).

Asdiscussed inSEA-EE-183, opencontactsofLimitorque limitswitchescanwithstand impressed voltagesof120VACand250VDCacrossthecontacts.

However,if120VACor250VDCwereimpressed onclosedcontactsofthelimitswitches, thecontactscouldweldshutifsufficient currentflowedforasufficient duration.

3.2ThisstudyislimitedtoUnit2digitalcomputerinputsdeveloped fromClass1ELimitorque motor-operators.

ASSUMPTIONS Thestudywasbasedonas-builtdrawingsandthedocuments issuedasofthedateoftaskinitiation.

Affiliated circuitsinthisstudyweretreatedthesameasClassIEcircuits.

Achangeinstateofacomputerinputcontactwhilethereisanimpressed voltagewasnotconsidered.

Onlythecontactintheopenorclosedpositionwasanalyzed.

L\'I~Il~c)~hY K~j~~1SEA-EE-226 Page4of64.0METHODSTheSusquehanna SESUnit2I/OSpecification Listing-DigitalRealwasreviewedtoidentifythecomputerinputsdeveloped fromLimitorque motor-operators equippedwithLimitorque limitswitches.

TheSusquehanna SESMotor-Operator Valve(MOV)IndexdatedOctober17,1989andsystemdrawingswerereviewedtodetermine whichMOVsaresafety-related Class1Evalves.Evaluation oftheimpactofwelded-shut Limitorque limitswitchesusedforcomputerinputswasperformed toassurethatthesedevicescanperformtheirsafety-related functions withweldedcomputerinputlimitswitches.

5.0 RESULTSReviewoftheSusquehanna

SESUnit2I/OSpecification ListingrevealedthatthenumberofcomputerpointsderivedfromClass1ELimitorque limitswitchesis40.Evaluation ofweldedcontactsforeachoftheselimitswitchesisprovided.

TheClass1ELimitorque limitswitchesarepartofmotor-operated valveswhichareinoneofthefollowing groups:l.Affiliated.

2.Requirenoautomatic operation.

3.Requireautomatic closure.Theaffiliated motor-operated valves,listedinTableI,arepoweredfromClass1Esources.However,thesevalvesandtheirlimitswitchesarenotusedinClass1Ecircuits.

Operation ofthesevalvesisnotrequiredfordesignbasiseventconditions.

Therefore, weldingacomputerinputlimitswitchdoesnoteffectClass1Ecircuits.

TheClass1Emotor-operated valveswhichrequirenoautomatic operation arelistedinTable2.Thesevalveshaveopenlimitswitchesforcomputerinputsduringnormalplantlineup.Theselimitswitchesarenotexposedtopotential welding.Intheeventthenormalplantlineupischanged,thevalveschangetotheirnewpositions beforethecomputerinputlimitswitchesareexposedtopotential welding.Therefore, weldingofthecomputerinputlimitswitchesdoesnotpreventthemotor-operated valvesfrommeetingtheirminimumperformance requirements.

rInadditiontothevalvesinTable2,theFeedwater InletStopCheckValvesHV-821-2F032A andHV-821-2F0328 motoroperators, whichareintheopenpositionduringnormalplantoperation, arenotrequiredtoautomatically operatefordesignbaseaccidents.

However,thesemotoroperators haveclosedlimitswitchesforcomputerinputsduringnormalplantoperation.

TheFeedwater InletStopCheckValvesaremotorassistedinordertoprovidethesevalveswithclosingcapability.

forprimarycontainment isolation leakageratetesting.Intheeventthelimitswitchesweldshut,theFeedwater InletStopCheckValveswillnotbe

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SEA-EE-226 Page5of6prevented fromclosingfordesignbaseaccidents sincethesevalvesarecheckvalves.Therefore, theweldingofthecomputerinputlimitswitchesdoesnotpreventHV-B21-2F032A andHV-B21-2F032B frommeetingtheirminimumperformance requirements.

TheClass1Evalveswhicharerequiredtooperatefordesignbaseaccidents areevaluated below:TheESWDiesel"E"CoolerSupplyValvesNos.HV-01110E andHV-01120E arerequiredtoautomatically closeforcertainDBA'swhentheDieselGenerator "E"isnotalignedandisbeingtested.Forthiscondition, thecomputerinputlimitswitchesareopenandarenotexposedtopotential welding.Ifthesevalvesreceiveanautomatic closesignal,thevalvechangespositionbeforethecomputerinputlimitswitchesareexposedtopotential welding.Therefore, theweldingofthesecomputerinputlimitswitchesdoesnotpreventHV-01110E andHV-01120E frommeetingtheirminimumperformance requirements.

TheReactorWaterCleanupIsolation ValvesHV-G33-2F001 andHV-G33-2F004 andtheMainSteamLineDrainIsolation ValvesHV-B21-2F016 andHV-B21-2F019 arerequiredtoautomatically closeforcertainDBA's.However,thecomputerinputlimitswitchesfromthesevalvesareclosedwhenthesevaivesareopen.Intheeventthecomputerinputlimitswitchesweldshut,thelimitswitchmaindriveshaftscouldperhapsbreaklooseinternaltothevalvescausingthevalvestojam,thuspotentially preventing fullclosureofthevalves.PerDanWarsingofLimitorque Corp.,thisisveryunlikely.

Morethanlikely,theweldedshutlimitswitchwillcausedamagetothelimitswitchgearing,butwillnotpreventthevalvesfromclosing.ToassurethattheHV-G33-2F001, HV-G33-2F004, HV-B21-2F016 andHV-B21-2F019 valvesmeettheirminimumperformance requirements withimpressed voltagefaultsontheircomputerinputcables,thecomputerinputlimitswitchesshouldberewiredsuchthatthesevalveschangepositions andmeettheirminimumperformance requirements beforethecomputerinputswitchesareexposedtopotential welding.Therewiredvalvelimitswitchesshouldbenormallyopenandclosedonlywhen'thevalvesare100%closed(i.e.switchclosedwhenthevalvesclosedintheprimarycontainment isolation position).

ThisactionisbeingtrackedbyNCR87-0021.REFERENCES 6.1IEEE279-1971.

6.2IEEE384-1974.

6.3Regulatory Guide1.75,Rev.0.6.4Susquehanna SESUnit2I/OSpecification Listingdated'ec.

8,1989.6.5Susquehanna SESMotor-Operator ValveIndexdatedOct.17,1989.6.6SEA-EE-183, Rev.0.6.7Susquehanna SESDesignDescription ManualChapter5,15and31.jpa/rpa042i(18)

~~Iv SEA-EE-226 Page6of6TABLE1AFFILIATED MOTOR-OPERATED VALVESHY-821-2F001 HV-821-2F002 HV-821-2F005 HV-831-2F023A HV-831-2F0238 HV-831-2F031A HV-831-2F0318 HV-831-2F032A HV-831-2F0328 TABLE2MOTOR-OPERATED VALVESNOAUTOMATIC OPERATION HV-01112A HV-011128 HV-01112C HV-01112D HV-01110A HV-011108 HV-01110C HV-011100 HV-01122A HV-011228 HV-01122C HV-01122DHV-01120A HV-011208 HV-01120C HV-011200 HV-01112E HV-01122EHV-821-2F020 HV-G33-2F042 HV-G33-2F104 HV-24182A HV-241828 jpa/rpa042i (18) r~~~~~<<f>>4