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

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

vibrationproximityprobesoneachCSIP.

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

thatthisproposedalternativedemonstratesanacceptablelevelofqualityandsafety.

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

performancetestresults.

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.govAttachments: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),issuedSeptember22,1999.

______________________________________________________________________________________OL=OperatingLicense

CP=ConstructionPermitAttachment2IN2001-06 Page1of1LISTOFRECENTLYISSUEDNRCINFORMATIONNOTICES_____________________________________________________________________________________InformationDateof

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