RIS 2000-03, Resolution of Safety Issue 158: Performance of Safety Related Power-Operated Valves Under Design Basis Conditions

Resolution of Safety Issue 158: Performance of Safety Related Power-Operated Valves Under Design Basis Conditions

ML003686003
Person / Time
Issue date:	03/15/2000
From:	Matthews D Division of Regulatory Improvement Programs
To:
Matthews D
References
GSI 158 RIS-00-003
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UNITEDSTATESNUCLEARREGULATORYCOMMISSIONOFFICEOFNUCLEARREACTORREGULATIONWASHINGTON,D.C.20555-0001March15,2000NRCREGULATORYISSUESUMMARY2000-03RESOLUTIONOFGENERICSAFETYISSUE158:PERFORMANCEOFSAFETY-RELATEDPOWER-OPERATEDVALVESUNDERDESIGNBASISCONDITIONS

Addressees

Allholdersofoperatinglicensesfornuclearpowerreactors,exceptthosewhohavepermanentlyceasedoperationsandhavecertifiedthatfuelhasbeenpermanentlyremoved fromthereactorvessel.

Intent

TheU.S.NuclearRegulatoryCommission(NRC)isissuingthisregulatoryissuesummary(RIS)toinformaddresseesoftheclosureofGenericSafetyIssue(GSI)158,"PerformanceofSafety- RelatedPower-OperatedValvesUnderDesignBasisConditions,"andofthestaff'sintentto continuetoworkwithindustrygroupsandtomonitoraddressees'activitiestoensurethat safety-relatedpower-operatedvalves(POVs)arecapableofperformingtheirspecified functionsunderdesignbasisconditions.Noactionorwrittenresponseisrequested.BackgroundInformationGSI-158,"PerformanceofSafety-RelatedPower-OperatedValvesUnderDesignBasisConditions,"wasidentifiedbytheNRCafterreactoroperatingexperienceandresearchresults onmotor-operatedvalves(MOVs),solenoid-operatedvalves(SOVs),air-operatedvalves (AOVs),andhydraulicallyoperatedvalves(HOVs)indicatedthattestingunderstaticconditions wasinsufficienttodemonstrateconsistentperformanceofthesevalvesunderdesign-basis conditions.Operatingeventsinvolvingobservedorpotentialcommon-causefailureswere documentedinNUREG-1275,"OperatingExperienceFeedbackReport,"Volumes2and6for airsystemsandSOVs,respectively,andinAEOD/C603,"ReviewofMotor-OperatedValve Performance,"forMOVs.TheseissuesarealsomorerecentlydiscussedinNUREG/CR-6644,

"GenericIssue158:PerformanceofSafety-RelatedPower-OperatedValvesUnderOperating Conditions."Tworelateddocuments,NUREG-1275,Vol.13,"EvaluationofAir-OperatedValves atU.S.Light-WaterReactors,"andNUREG/CR-6654,"AStudyofAir-OperatedValvesinU.S.

NuclearPowerPlants,"arefocusedspecificallyonAOVs.MOVperformanceissueswerenotdiscussedinGSI-158,astheyweredocumentedpreviouslyintheresolutionofTMIActionPlanItemII.E.6.1,"InSituTestingofValves-TestAdequacy Study,"whichisincludedinNUREG-0933,"PrioritizationofGenericSafetyIssues."Resolution ofthisissueresultedintheissuanceofGenericLetter(GL)89-10,"Safety-RelatedML003686003 RIS2000-03March15,2000

Page2of4Motor-OperatedValveTestingandSurveillance,"andsubsequentlyGL96-05,"PeriodicVerificationofDesignBasisCapabilityofSafety-RelatedMotor-OperatedValves."TheNRCstaffbriefedtheAdvisoryCommitteeonReactorSafeguards(ACRS)onMay6,1999,andpresentedtheresultsofstaffandcontractorstudiesofthePOVissue.Thestaffconcluded thatnonewregulationswererequiredtoaddresstheissuescontainedinGSI-158.Thecurrent regulationsprovideanadequateframeworktoaddressspecificPOVissuessimilartoMOV

issuesthatwereresolvedthroughtheissuanceofGL89-10andGL96-05.Thestaffalso describedthevoluntaryindustryinitiativebeingdevelopedtoaddressAOVissues.Inits May14,1999,lettertotheNRCstaff,theACRSstatedthatthecentralissue,whetherPOVs areabletoperformtheirintendedfunctionsunderdesignbasisdynamicconditions,hadnot beenadequatelyaddressed.TheACRSfurtherstatedthatunlesstheNRCstaffundertakesa pro-activeefforttoensureresolutionofthisissue,theindustryinitiativewillremainanoptional, voluntaryprogramthatwillnotfullyresolvetheconcernsofGSI-158.MostoftherecentstaffandindustryattentionhasbeenfocusedonAOVperformance.TheNRCstaffstatedinaJuly2,1999,lettertotheACRSthatitwouldcontinuetomonitorandwork withindustrygroupsdevelopingdesignbasisverificationandtestingprogramsforAOVs.The NRCstaffnotedfurtherthatiftheactionsoftheindustrydidnotadequatelyaddressthe functionalityofPOVsunderdesignbasisdynamicconditions,theNRCstaffwouldtake additionalregulatoryactionasappropriate.TheNRCstaffpreviouslyrequestedthattheindustryverifythecapabilityofAOVswithrespecttoissuesinvolvingtheplantinstrumentairsupplysystem.InGL88-14,"InstrumentAirSupply SystemProblemsAffectingSafety-RelatedEquipment,"addresseeswererequestedtoverifyby testthatair-operatedsafety-relatedcomponentswillperformasexpectedinaccordancewithall design-basisevents.Alladdresseeswererequiredtorespondtothegenericletterwith confirmationthatthisverificationhadbeenperformed.Allresponseswerereceivedby1993 andthegenericletterwassubsequentlyclosed.RecentAOVPerformanceandSafetySignificanceArecentNRCstudyofAOVs,documentedinNUREG-1275,Vol.13,andNUREG/CR-6654,includedareviewofAOVoperatingexperienceandtheresultsof7sitevisitsto11U.S.light waterreactorsconductedin1997-1998.Thesevenlicenseescollectivelyidentifiedatotalof

167safety-related,high-risk-significantAOVs,rangingfromanindividualreactorfacilityhighof

36AOVstoalowof4AOVs.Inaddition,twoofthoselicenseesidentifiedatotalof15AOVs thatwerenonsafety-relatedbuthigh-risk-significant.Mostofthelicenseesvisitedwere planningtoverifythedesign-basiscapabilityofallthereferencedAOVs.Thelicensees'

determinationsofthehigh-risk-significantAOVswerebasedonavarietyofmethods,including plant-specificprobabilisticriskassessment,individualplantexamination,andmaintenancerule expertpanelreviews.Manyofthelicensees'determinationsincludedevaluationsoftherisk achievementworth(RAW)andFussell-Vesely(F-V)riskrankingsoftheAOVs.Each categorizationmethodwasunique.ThemajorsafetyconcernidentifiedintheNRCAOVstudyfromariskperspectiveisthesimultaneouscommon-causefailureofAOVswhichdisableredundanttrainsofasystem importanttosafety.Thescenarioofmostconcernisthatduringanaccidentortransient,AOVs RIS2000-03March15,2000

Page3of4inredundanttrainsofasafetysystemfailwhensubjectedtopressure,temperature,andflowconditionsdifferentfromthoseseenduringnormaloperationortesting.Asdiscussedinthe NRCAOVstudy,somelicenseesfoundthatcertainAOVshadhighRAWand/orF-Vrisk rankings.Table6ofNUREG/CR-6654includestheRAWvaluesforAOVsthatwerecalculated bylicenseesatthreeplants.Thesecalculationsshowedthat,insomecases,theRAWcould increasebyoneortwoordersofmagnitudeasaresultofcommon-causefailures.RAWfor common-causeAOVfailuresatthosethreeplantsrangedfromslightlyover1to202.

Weaknessesinthedesign,testing,andmaintenanceofAOVscouldresultincommon-cause AOVfailureswhicharenotaddressedinplantsafetyanalyses.Thecommon-causeAOV

failuresthathavebeendocumentedintheAOVstudydidnotoccursimultaneouslywith design-basistransientsbutwereidentifiedduringoperations,maintenance,ortesting.IndustryInitiativesTheJointOwnersGrouponAirOperatedValves(JOGAOV),whichisfacilitatedbytheNuclearEnergyInstitute(NEI),presentedtotheNRCstaffinapublicmeetingonJune3,1999,the industry'svoluntaryprogramtoaddressAOVissues.TheJOGAOVprogramprovides guidancetoverifyvalveperformanceatdesignconditionsandlong-termperiodicverificationof safety-relatedAOVscategorizedashigh-risk-significant.Forsafety-related,low-risk-significant AOVsandAOVsthatarenotsafety-relatedbutaredeterminedtobehigh-risk-significant,the JOGAOVprogramalsoprovidesguidanceforaless-rigorousverificationofvalvefunctionality.

Theactivitiesforsafety-related,low-risk-significantAOVsandnonsafety-related,high-risk- significantAOVswouldnotnecessarilyinvolveverificationthatthevalveswouldperformunder designconditionsorrequirelong-termperiodicverification.Themethodologytodetermine valvesafetysignificance,asspecifiedintheindustryprogram,mayincludesuchriskinsight methodsasinRegulatoryGuide1.174,"AnApproachforUsingProbabilisticRiskAssessment inRisk-InformedDecisionsonPlant-SpecificChangestotheLicensingBasis,"orprograms establishedtomeettherequirementsof10CFR50.65,"Requirementsformonitoringthe effectivenessofmaintenanceatnuclearpowerplants",(themaintenancerule)incombination withindividualplantexaminationsandthereviewperformedbyaseparateexpertpanel.Thisindustryprogramdocumentwascompletedanddistributedtoutilitiesin1999.TheNRCreceivedacopyoftheprogramdocumentinaletterfromD.Modeen(NEI)toE.Imbro(NRC),

datedJuly19,1999.NRCcommentsontheJOGAOVprogramanditsimplementationwere senttoNEIinaletterfromE.ImbrotoD.Modeen,datedOctober8,1999.Althoughthe programwasnotedtohavesomelimitations,theNRCstaffrecognizesthatindustry-wide implementationofthisprogramwouldachieveauniformlevelofconsistencythatwouldprovide increasedconfidenceinthedesign-basiscapabilitiesofhigh-risk-significantAOVsinnuclear powerplants.Asstatedabove,theNRCwillcontinuetoworkwithindustrygroupstoensure thatsafety-relatedPOVsarecapableofperformingtheirspecifiedfunctionsunderdesignbasis conditions.IfPOVfunctionalityunderdesignbasisconditionsisnotadequatelyaddressedby theindustry,theNRCstaffwilltakeadditionalregulatoryactionasappropriate.SummaryoftheIssueTheNRChasclosedGSI-158onthebasisthatcurrentregulationsprovideadequaterequirementstoensureverificationofthedesign-basiscapabilityofPOVsandthatnonew RIS2000-03March15,2000

Page4of4regulatoryrequirementsareneeded.TheNRCstaffwillcontinuetoworkwithindustrygroupsonanindustry-wideapproachtothePOVissueandtoprovidetimely,effective,andefficient resolutionoftheconcernsregardingPOVperformance.TheNRCstaffwillalsocontinueto monitorlicensees'activitiestoensurethatPOVsarecapableofperformingtheirspecified safety-relatedfunctionsunderdesign-basisconditions.VoluntaryInitiativesAlthoughtherearenoregulatoryrequirementsforlicenseestoestablishanAOVprogram,licenseesarerequiredby10CFR50.65tomonitortheperformanceofstructures,systems,or components(SSCs)inamannersufficienttoprovidereasonableassurancethatsuchSSCs (e.g.,systemswithsafety-relatedandhigh-safety-significantAOVs)arecapableoffulfillingtheir intendedfunctions.

Addressees

whoimplementtheJOGAOVprogramtohelpensurethe designbasiscapabilityofAOVsmaywishtoconsidertheNRCcommentscontainedinthe NRC'slettertoNEIdatedOctober8,1999.

Addressees

whochoosetodevelopplant-specific AOVprogramsmaywishtoconsidertheattributeslistedintheattachmenttothisRIS.These attributesarebasedonlessonslearnedfromthestaff'sinvolvementintheactivitiesrelatedto GL89-10andtheNRCsitevisitsdocumentedinNUREG/CR-6654.BackfitDiscussionThisRISrequestsnoactionorwrittenresponse.Therefore,thisRISisnotabackfitunder10CFR50.109,andthestaffdidnotperformabackfitanalysis.FederalRegisterNotificationAnoticeofopportunityforpubliccommentwasnotpublishedintheFederalRegister becausethisRISisinformationalandtheNRCstaffdiscussedtheclosureofGSI-158inapublic meetingwiththeACRS.IfyouhaveanyquestionsaboutthisRIS,pleasecontactoneofthetechnicalcontactslistedbelow./RA/S.F.NewberryFORDavidB.Matthews,DirectorDivisionofRegulatoryImprovementPrograms OfficeofNuclearReactorRegulation Attachments:1.SuccessfulPower-OperatedValveProgram

2.ListofRecentlyIssuedNRCRegulatoryIssueSummariesTechnicalContacts:JosephColaccino,NRRHaroldL.Ornstein,RES301-415-2753301-415-7574 E-mail:jxc1@nrc.govE-mail:hlo@nrc.gov RIS2000-03March15,2000

Page4of4regulatoryrequirementsareneeded.TheNRCstaffwillcontinuetoworkwithindustrygroupsonanindustry-wideapproachtothePOVissueandtoprovidetimely,effective,andefficient resolutionoftheconcernsregardingPOVperformance.TheNRCstaffwillalsocontinueto monitorlicensees'activitiestoensurethatPOVsarecapableofperformingtheirspecified safety-relatedfunctionsunderdesign-basisconditions.VoluntaryInitiativesAlthoughtherearenoregulatoryrequirementsforlicenseestoestablishanAOVprogram,licenseesarerequiredby10CFR50.65tomonitortheperformanceofstructures,systems,or components(SSCs)inamannersufficienttoprovidereasonableassurancethatsuchSSCs (e.g.,systemswithsafety-relatedandhigh-safety-significantAOVs)arecapableoffulfillingtheir intendedfunctions.

Addressees

whoimplementtheJOGAOVprogramtohelpensurethe designbasiscapabilityofAOVsmaywishtoconsidertheNRCcommentscontainedinthe NRC'slettertoNEIdatedOctober8,1999.

Addressees

whochoosetodevelopplant-specific AOVprogramsmaywishtoconsidertheattributeslistedintheattachmenttothisRIS.These attributesarebasedonlessonslearnedfromthestaff'sinvolvementintheactivitiesrelatedto GL89-10andtheNRCsitevisitsdocumentedinNUREG/CR-6654.BackfitDiscussionThisRISrequestsnoactionorwrittenresponse.Therefore,thisRISisnotabackfitunder10CFR50.109,andthestaffdidnotperformabackfitanalysis.FederalRegisterNotificationAnoticeofopportunityforpubliccommentwasnotpublishedintheFederalRegister becausethisRISisinformationalandtheNRCstaffdiscussedtheclosureofGSI-158inapublic meetingwiththeACRS.IfyouhaveanyquestionsaboutthisRIS,pleasecontactoneofthetechnicalcontactslistedbelow./RA/S.F.NewberryFORDavidB.Matthews,DirectorDivisionofRegulatoryImprovementPrograms OfficeofNuclearReactorRegulation Attachments:1.SuccessfulPower-OperatedValveProgram

2.ListofRecentlyIssuedNRCRegulatoryIssueSummariesTechnicalContacts:JosephColaccino,NRRHaroldL.Ornstein,RES301-415-2753301-415-7574 E-mail:jxc1@nrc.govE-mail:hlo@nrc.govDOCUMENTNAME:G:\EMEB\COLACCINO\RIS00-XX.WPD*previouslyconcurred*previouslyconcurredML003686003NRR-052**concurredviae-mailINDICATEINBOX:"C"=COPYW/OATTACHMENT/ENCLOSURE,"E"=COPYW/ATT/ENCL,"N"=NOCOPYOFFICIALRECORDCOPYOFFICEEMEB:DETECH:EDEMEB:DEEMEB:DERES:DSAREDD:DED:DENAMEJColaccino*RSandersDTeraoEImbroCRossi*RWessman*JStrosnider*DATE01/03/0012/27/99**01/03/00*01/06/00*2/8/0001/14/001/28/00OFFICEADPT*REXB*REXB:DRIP*D:DRIPNAMEBSheronJShapakerLMarshDMatthewsDATE2/13/003/8/003/8/00//00

Attachment1RIS2000-03 March15,2000

Page1of2ATTRIBUTESOFASUCCESSFULPOWER-OPERATEDVALVEDESIGNCAPABILITYANDLONG-TERMPERIODICVERIFICATIONPROGRAM1.Includeallmaintenancerulescopepower-operatedvalves(POVs)inprogram.2.VerifyPOVsinnon-safetypositionarecapableofreturningtotheirsafetypositioniftrainisassumedoperablewithvalvesintheirnon-safetyposition.3.Forair-operatedvalves,verifyguidanceinGL88-14,"InstrumentAirSupplySystemProblemsAffectingSafety-RelatedEquipment,"hasbeensuccessfullyimplemented, includingperiodicmonitoringofairquality.4.Evaluatemotor-operatedvalve(MOV)risk-rankingmethodologiesdevelopedbytheBoilingWaterReactorOwnersGroupandtheWestinghouseOwnersGroupfor applicabilitytoriskrankingofPOVsatthespecificplant,asapplicable.5.Focusinitialeffortsonsafety-related,active,high-riskPOVs.Informationobtainedfromthesevalvesandlessonslearnedmaybeusedtoverifyandmaintaindesignbasis capabilityofsimilarsafety-relatedPOVs.6.VerifymethodsforpredictingPOVoperatingrequirementsusingMOVlessonslearnedorspecificPOVdynamicdiagnostictesting.UseoftheElectricPowerResearchInstitute (EPRI)MOVPerformancePredictionMethodmustincludeallguidelineaspectsofthat methodologyandnotonlyindividualEPRIvalvetestresults.7.JustifymethodforpredictingPOVactuatoroutputcapabilitybytest-basedprogramestablishedbythevendor,licensee,orindustry.8.Addressallapplicableweaklinks,includingactuator,valve,andstem.

9.Ensurequalityassuranceprogramcoverage.

10.Providesufficientdiagnosticswhenbaselinetestingtoverifycapability.Diagnosticsmightnotbeneededifnormalplantoperationfrequentlydemonstratesdesignbasiscapability.11.Specifywhendynamicorstaticdiagnosticperiodictestingisneeded.

12.Ensurepost-maintenancetestingisadequatetoverifycapabilityofallsafety-relatedPOVsandrisk-significantfunctionsofnon-safety-relatedPOVs.13.EnsurePOVmaintenanceproceduresarereviewedtoincorporatelessonslearnedfromothervalveprograms.

Attachment1RIS2000-03 March15,2000

Page2of214.Upgradetrainingtoincorporatelessonslearnedfromothervalveprograms.15.Applyfeedbackfromplant-specificandindustryinformation,includingtestdata,toallapplicablesafety-relatedPOVs.16.Establishquantitative(testdata)andqualitative(maintenanceandconditionreports)trendingofPOVperformancewithdetailedreviewfollowingeachrefuelingoutage.

_______________________________________________________________________________________OL=OperatingLicense CP=ConstructionPermitAttachment2RIS2000-03 March15,2000

Page1of1LISTOFRECENTLYISSUEDNRCREGULATORYISSUESUMMARIES

_____________________________________________________________________________________RegulatoryIssueDateofSummaryNo.SubjectIssuanceIssuedto

_____________________________________________________________________________________2000-02ClosureofGenericSafetyIssue23,ReactorCoolantPumpSeal Failure2/15/2000AllholdersofOLsfornuclearpowerreactors,exceptforthose licenseeswhohavepermanently ceasedoperationsandhave certifiedthatfuelhasbeen permanentlyremovedfromthe reactorvessel2000-01ChangesConcerningForeignOwnership,Control,orDomination ofNuclearReactorLicensees01/27/2000AllNRClicensees1999-06VoluntarySubmissionofPerformanceIndicatorData12/01/1999AllholdersofOLsfornuclearreactors,exceptforthose licenseeswhohavepermanently ceasedoperationsandhave certifiedthatfuelhasbeen permanentlyremovedfromthe reactorvessel1999-05ImplementingProcedureforPowerReactorNOEDsProcessedDuring theY2KTransition12/01/1999AllholdersofOLsfornuclearpowerreactors,exceptforthose licenseeswhohavepermanently ceasedoperationsandhave certifiedthatfuelhasbeen permanentlyremovedfromthe reactorvessel1999-04SourcesofInformationPreviouslyPublishedintheAEODAnnual Report11/23/1999AllNRClicensees