Information Notice 2001-06, Centrifugal Charging Pump Thrust Bearing Damage Not Detected Due to Inadequate Assessment of Oil Analysis Results and Selection of Pump Surveillance Points

Centrifugal Charging Pump Thrust Bearing Damage Not Detected Due to Inadequate Assessment of Oil Analysis Results and Selection of Pump Surveillance Points

ML011070643
Person / Time
Issue date:	05/11/2001
From:	Marsh L B Operational Experience and Non-Power Reactors Branch
To:
References
IN-01-006
Download: ML011070643 (7)

UNITEDSTATESNUCLEARREGULATORYCOMMISSIONOFFICEOFNUCLEARREACTORREGULATIONWASHINGTON,D.C.20555-0001May11,2001NRCINFORMATIONNOTICE2001-06:CENTRIFUGALCHARGINGPUMPTHRUSTBEARINGDAMAGENOTDETECTEDDUETO INADEQUATEASSESSMENTOFOILANALYSIS RESULTSANDSELECTIONOFPUMP SURVEILLANCEPOINTS

Addressees

Allholdersofoperatinglicensesfornuclearpowerreactors,exceptthosewhohavepermanentlyceasedoperationsandhavecertifiedthatfuelhasbeenpermanentlyremoved fromthereactor.

Purpose

TheU.S.NuclearRegulatoryCommission(NRC)isissuingthisinformationnoticetoalertaddresseesthatinadequateassessmentofpumpoilanalysisresults,combinedwith surveillancetestingwhichdoesnotmonitorallrelevantpumpoperatingconditions,mayallow severepumpdegradationtogoundetected.Itisexpectedthatrecipientswillreviewthe informationforapplicabilitytotheirfacilitiesandconsideractions,asappropriate,toavoid problems.However,thesuggestionscontainedinthisinformationnoticearenotNRC requirements;therefore,nospecificactionorwrittenresponseisrequired.DescriptionofCircumstancesOnJune19,2000,whiledisassemblingtheCcharging/safetyinjectionpump(CSIP)toreplaceamechanicalseal,ShearonHarrisNuclearPlant(SHNP)personneldiscoveredsignificant damagetotheoutboardthrustbearing.Furtherexaminationrevealedthatthebabbittmaterial onthebearingshoesofthismulti-padthrustbearinghadmeltedandre-solidifiedwithinthe thrustbearingcagearea.Onboththeshoesandthesleeveofthethrustbearing,radialwearin thedirectionofnormalpumprotationwasindicativeofmetal-to-metalcontactbetweenthetwo surfaces.Theinboardradialbearingandshaftalsohadminorwear.SHNPstatedina licenseeeventreport(Reference1)thatthemostprobablecauseofthedamagewasa momentarylossoflubricationflowtotheoutboardthrustbearing.Aninadequatefill-and-ventof thepump,whichmayhavecausedamomentaryincreaseintheaxialthrustontheoutboard thrustbearing,wasalsogivenasapotentialrootcause.ElementalanalysisofaroutinepumpbearingoilsampletakenonSeptember19,1999,usingadirectcurrentplasma(DCP)spectrometer,revealeda40-foldincreaseintheparticlecountin therangeof5to10micronsovertheprevioussampletakenonMay11,1999.(Theparticle countincreasedfrom15,800to660,000countsper100millilitersample.)AllothertestedML011070643 IN2001-06Page2of5parameterswerenormal.SHNPreviewedtheElectricPowerResearchInstitute(EPRI)LubricationGuide(Reference2)andconcludedthatthesizerangeofthesewearparticleswas consistentwithbenignwear.ThebearingoilintheCSIPwasreplacedonDecember21,1999, andSHNPcontinuedsamplingat6-monthintervals.Thenextoilsample,takenon February23,2000,alsoshowedahighparticlecountinthe5to10micronrange.Trace amountsofironandtinwerealsodetectedforthefirsttime.Theanalysisofanotheroilsample takenonJune18,2000,foundthatthelevelsofallparametersweresimilartothelevelsinthe February23,2000,sample.EachCSIPatSHNPisaPacificModel21/2RLIJ,11-stage,centrifugalpumpmanufacturedbyFlowserveCorporation,formerlyIngersoll-DresserPumpCompany.TheCCSIPisthestandby pump.Duringtheperiodinwhichhighparticlecountsinthethreeoilsamplesweredetected, theCpumpwasintermittentlyinservicetosupportplantoperations.Surveillancetesting,as requiredbytheSHNPinservicetestingprogramandtheSHNPTechnicalSpecifications,was performedontheCpumpduringthisperiod.Inservicetests,includingvibrationmeasurement, wereconductedduringplantoperationonNovember13,1999,andJanuary3,2000,withthe pumpoperatingatthenormalchargingflowrateofapproximately90gallonsperminute(gpm).

PerformancedatafrombothtestsindicatedtheCCSIPmettheestablishedpumphydraulic andmechanicalacceptancecriteriaintheAmericanSocietyofMechanicalEngineers(ASME)

CodeforOperationandMaintenanceofNuclearPowerPlants(OMCode),andnoadverse trendswerenoted.OnApril23,2000,arefuelingoutagetesttosatisfytheSHNPtechnical specificationswasperformedsuccessfully,withthepumpachievingaflowrateof609gpm.Subsequenttothediscoveryoftheseverelydegradedoutboardpumpthrustbearing,discussionswiththepumpmanufacturerrevealedthatatflowratesbetweenapproximately250 and600gpm,thenetaxialthrustofeachSHNPCSIPpumpisinthedirectionoftheoutboard thrustbearing.Therefore,SHNPconcludedthatduringnormalplantoperationandsurveillance testing,theoutboardthrustbearinghadbeeneithernotloadedoronlylightlyloaded.In addition,SHNPcouldnotassessthecapabilityoftheCCSIPtoperformitsfunctionduringa small-break,loss-of-coolantaccident,inwhichthepumpaxialthrustwouldhavefullyloadedthe outboardthrustbearing.InresponsetoanNRCnoticeofviolation(Reference3),SHNPdescribedcorrectivestepseithercompletedorinprogresstoaddressthisissue.Theseincluded(1)counselingoperators onconsequencesofimproperpumpfill-and-ventoftheCSIP,(2)establishingoilanalysis criteriaforincreasedlubricantparticlecounts,(3)reinforcingexpectationsfordispositionof abnormalindications,(4)samplingCSIPlubricatingoilquarterlyinsteadofsemi-annually, (5)revisingthemaintenanceproceduretoensurethattheCSIPlubricatingoilsystemwill functionasexpected,and(6)implementingadesignmodificationtoinstalltemperatureand vibrationproximityprobesoneachCSI IN2001-06Page3of5NRCRequirementsandIndustryGuidanceandPracticesonPumpConditionMonitoringThecurrentrequirementsforinservicetestingofsafety-relatedpumpsarespecifiedinSection50.55aofTitle10oftheCodeofFederalRegulations(10CFR50.55a),"Codesand Standards."Forplantswhicharerequiredtoupdatetheirinservicetesting(IST)programsafter September22,2000,whichisoneyearaftertherecentchangeto10CFR50.55a(Reference 4),Subsection(b)(3)requiresthatsafety-relatedpumpsbetestedtothe1995Editionandthe 1996AddendaoftheASMEOMCode.TheCoderequiresthatsafety-relatedpumpsbetested bienniallyat+/-20%oftheirdesignflowrate,andeverythreemonthsatspecificreferencepoints.

OverallvibrationmeasurementsofeachpumpbearingaretakenasspecifiedbytheCode.The SHNPISTprogramisinaccordancewithanearlierversionoftheCode,whichrequirespump testingtobeconductedeverythreemonthsatreferencepointsofoperationreadilyduplicated duringsubsequenttests.Pumphydraulicperformanceisassessedbycomparingcurrent performancewithreferencevaluesestablishedwhenthepumpisknowntobeoperating acceptably.Pumpmechanicalperformanceisassessedlikehydraulicperformance,unlessthe specifiedmultipleofthemeasuredoverallvibrationreferencevalueexceedstheabsolute vibrationacceptancecriterion.NeithertheCodenortheregulationsrequireanyspecificpumpconditionmonitoringactivitiestobeperformedonsafety-relatedpumps.However,theNRChasobservedduringinspection activitiesthatmanyUScommercialnuclearpowerplantshavesometypeofcondition monitoringprogramfortheirrotatingmachinery.Theseprogramsusuallyincludebothsafety- relatedandnon-safety-relatedequipment.Becausenoregulationscovertheseprograms,the testingperformed,theexaminationscompleted,andtheacceptancecriteriausedforeach conditionmonitoringactivityvarywidely.TheEPRILubricationGuideincludesinformationonthetestingandanalysisoflubricants.Theguideidentifiesparticlesizeandwear-metalcontentaskeypropertiestoanalyze.Theguide alsoprovides"classic"warninglimitsforcertainmeasuredproperties.Theguidedoesnot recommendaspecificwarninglimitforparticlecount.However,theguideemphasizestrending criticalpropertiesofaspecificapplicationandestablishingappropriatewarninglimits.When theselimitsareexceededandtheresultsareverified,theguiderecommendsoilreplacement andfurtherstudyifnecessary.TheNRChasauthorizedalternativestotheCodevibrationrequirementsbasedontheperformanceofpumpconditionmonitoringactivities.Forexample,aspartofanalternativeto theCodevibrationacceptancecriterion,onefacilitycommittedtoimplementaplant-specific pumpconditionmonitoringprogramforcertainsafety-relatedpumps.TheNRChasdetermined thatthisproposedalternativedemonstratesanacceptablelevelofqualityandsafet IN2001-06Page4of5DiscussionAkeyfactorinthefailuretodiscoverthedamagedbearingbeforedisassemblywasnotactivelypursuingtherootcauseoftheabnormallyhighparticlecountintheSeptember19,1999,oil sample.TheEPRIguideimpliesthatparticleslessthan10micronsinsizearegeneratedfrom

"benignwear."Theguidedoesnotdiscussthesignificanceofchangesinwearparticle concentration.However,theguidedoesdiscusstrendingofparameters.SHNPperformed spectroscopicanalysisofeachsampleandtrendedtheresultsofthesetests.Thelowweight percentofthewearparticleswasapparentlythereasonwhytheelementalanalysisdidnot detectthepresenceofbearingmaterial.Ferrographyandelectronmicroscopicscan examinationwereconductedafterthediscoveryofthebearingdegradationandthereforewere notafactorindiagnosingtheelevatedparticlecount.SHNPelectedtocontinuewitharoutine oilsamplingscheduledespitethehighparticlecountandthelackofaplausiblerootcausefor thiscondition.Amoreaggressiveoilsamplingschedule(e.g.,weekly)wouldlikelyhave revealedtheseverelydegradedoutboardthrustbearingseveralmonthsbeforethepumpwas disassembled.Inserviceandtechnicalspecificationsurveillancetestingdidnotindicatethattheoutboardthrustbearingwasseverelydamaged.Thepurposeofpumpinservicetestingistoidentify degradationbeforethepump'sperformanceofitssafety-relatedfunctionisimpaired.Forthe chargingpumpsattheSHNP,thepurposeoftechnicalspecificationtestingistoverifythatthe pumpwilldeliveraspecificflowattherequiredtotaldevelopedhead.Thefailureofbothtests toindicatebearingdegradationappearstohavebiasedthedecisiontonotinvestigatethe elevatedparticlecount.Informationprovidedbythevendorrevealedareversalinthedirectionofthepumpaxialforceasafunctionofthepumpflowrate.ThispumpdesigncharacteristicwasunknowntoSHNP personnelbeforetheydiscoveredtheseverelydegradedbearingandthentalkedwiththe vendor.TheCodedoesnotrequireSHNPtoaccountforthisdesignconditionthroughtesting.

Thetechnicalspecificationfullflowtestafterthefirstdetectionofthehighparticlecountneither detectedthisconditionnorcausedacatastrophicfailureofthepump.Thisissueillustratesthat theassessmentofsafety-relatedpumpperformanceisdependentnotonlyonverifying successfulsurveillancetesting,butalsoonunderstanding(1)pumpandsystemdesignand performancecharacteristics,(2)performancetestingresults,and(3)theresultsofcondition monitoringactivitiesandtheircorrelationwithknownpumpdesigncharacteristicsand performancetestresult IN2001-06Page5of5GenericImplicationsIftrendsofconditionmonitoringdataarenotactivelyinvestigatedwhentheydeviatefromanestablishedbaseline,alicenseemayoverlooksignificantpumpdegradationthatisnotdetected byperformancetesting.Thisinformationnoticerequiresnospecificactionorwrittenresponse.Ifyouhaveanyquestionsaboutthisnotice,pleasecontactoneofthetechnicalcontactslistedbeloworthe appropriateOfficeofNuclearReactorRegulation(NRR)projectmanager./RA/LedyardB.Marsh,Chief EventsAssessment,GenericCommunicationsandNon-PowerReactorsBranchDivisionofRegulatoryImprovementPrograms OfficeofNuclearReactorRegulationTechnicalcontacts:J.Colaccino,NRRBobHagar,RegionII301-415-2753919-362-0601 E-mail:jxc1@nrc.govE-mail:rch2@nrc.gov:

Attachments:

1.ListofReferences 2.ListofRecentlyIssuedInformationNotices IN2001-06Page5of5GenericImplicationsIftrendsofconditionmonitoringdataarenotactivelyinvestigatedwhentheydeviatefromanestablishedbaseline,alicenseemayoverlooksignificantpumpdegradationthatisnotdetected byperformancetesting.Thisinformationnoticerequiresnospecificactionorwrittenresponse.Ifyouhaveanyquestionsaboutthisnotice,pleasecontactoneofthetechnicalcontactslistedbeloworthe appropriateOfficeofNuclearReactorRegulation(NRR)projectmanager./RA/LedyardB.Marsh,Chief EventsAssessment,GenericCommunicationsandNon-PowerReactorsBranchDivisionofRegulatoryImprovementPrograms OfficeofNuclearReactorRegulationTechnicalcontacts:J.Colaccino,NRRBobHagar,RegionII301-415-2753919-362-0601 E-mail:jxc1@nrc.govE-mail:rch2@nrc.gov

Attachments:

1.ListofReferences 2.ListofRecentlyIssuedInformationNoticesDistribution:INReadingFilePUBLICADAMSACCESSIONNUMBER:ML011070643Template#=NRR-052ÿPubliclyAvailableNon-PubliclyAvailableSensitiveÿNon-SensitiveOFFICETechEditor)REXB:DRIPEMEB:DEEMEB:DENAMEPKleene*RHagar*JColaccino*DTerao*DATE04/09/200104/09/200104/10/200104/18/2001OFFICEEMEB:DEREXB:DRIPD:DEREXB:DRIPNAMEGImbro*JTappert/txkfor*JStrosnider*LDATE04/18/200104/24/200105/03/2001OFFICIALRECORDCOPY Attachment1Page1of1References1.ShearonHarrisNuclearPowerPlantUnit1,DocketNumber50-400,LicenseeEventReport2000-007-01,"TechnicalSpecificationsViolationDuetoInoperableCharging SafetyInjectionPump,"datedMarch12,2001.2.NP-4916-R2,ElectricPowerResearchInstitute/NuclearMaintenanceApplicationsCenterLubricationGuide,Revision2,publishedFebruary1995.3.ShearonHarrisNuclearPowerPlantUnit1,DocketNumber05000-400,ReplytoNoticeofViolation(NRCInspectionReportNumbers50-400/00-03,50-400/00-10)dated March2,2001.4.FederalRegister,Volume64,Number183,"IndustryCodesandStandards;AmendedRequirements,"(10CFRPart50),issuedSeptember22,199 ______________________________________________________________________________________OL=OperatingLicense CP=ConstructionPermitAttachment2IN2001-06 Page1of1LISTOFRECENTLYISSUEDNRCINFORMATIONNOTICES_____________________________________________________________________________________InformationDateof NoticeNo.SubjectIssuanceIssuedto______________________________________________________________________________________2001-05Through-WallCircumferentialCrackingofReactorPressure VesselHeadControlRodDrive MechanismPenetration NozzlesatOconeeNuclear Station,Unit304/30/01Allholdersofoperatinglicensesforpressurizedwaternuclear powerreactorsexceptthosewho haveceasedoperationsandhave certifiedthatfuelhasbeen permanentlyremovedfromthe reactorvessel2001-04NeglectedFireExtinguisherMaintenanceCausesFatality04/11/01Allholdersoflicensesfornuclearpower,research,andtestreactors andfuelcyclefacilities2001-03IncidentReportingRequirementsforRadiography Licensees04/06/01Allindustrialradiographylicensees2001-02SummaryofFitness-for-DutyProgramPerformanceReports forCalendarYears1998and 199903/28/01Allholdersofoperatinglicensesfornuclearpowerreactors,and licenseesauthorizedtopossess oruseformulaquantitiesof strategicspecialnuclearmaterial (SSNM)ortotransportformula quantitiesofSSNM2001-01TheImportanceofAccurateInventoryControlstoPrevent theUnauthorizedPossession ofRadioactiveMaterial03/26/01Allmateriallicensees2000-17,Supp.2CrackinWeldAreaofReactorCoolantSystemHotLegPiping atV.C.Summer02/28/01Allholdersofoperatinglicensesfornuclearpowerreactorsexcept thosewhohasceasedoperations andhavecertifiedthatfuelhas permanentlyremovedfrom reactorvessel2000-22MedicalMisadministrationsCausedbyHumanErrors InvolvingGammaStereotactic Radiosurgery(GAMMAKNIFE)12/18/00Allmedicaluselicenseesauthorizedtoconductgamma stereotacticradiosurgery treatments