Information Notice 2000-08, Inadequate Assessment of the Effect of Differential Temperatures on Safety-Related Pumps: Difference between revisions
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| issue date = 05/15/2000 | | issue date = 05/15/2000 | ||
| title = Inadequate Assessment of the Effect of Differential Temperatures on Safety-Related Pumps | | title = Inadequate Assessment of the Effect of Differential Temperatures on Safety-Related Pumps | ||
| author name = Marsh L | | author name = Marsh L | ||
| author affiliation = NRC/NRR/DRIP/REXB | | author affiliation = NRC/NRR/DRIP/REXB | ||
| addressee name = | | addressee name = | ||
Revision as of 11:30, 14 July 2019
| ML003712586 | |
| Person / Time | |
|---|---|
| Issue date: | 05/15/2000 |
| From: | Marsh L Operational Experience and Non-Power Reactors Branch |
| To: | |
| Petrone, C | |
| References | |
| TAC MA8653 IN-00-008 | |
| Download: ML003712586 (5) | |
UNITEDSTATESNUCLEARREGULATORYCOMMISSIONOFFICEOFNUCLEARREACTORREGULATIONWASHINGTON,D.C.20555-0001May15,2000NRCINFORMATIONNOTICE2000-08:INADEQUATEASSESSMENTOFTHEEFFECTOFDIFFERENTIALTEMPERATURESONSAFETY-
RELATEDPUMPS
Addressees
Allholdersofoperatinglicensesfornuclearpowerreactors.
Purpose
TheU.S.NuclearRegulatoryCommission(NRC)isissuingthisinformationnoticetoinformaddresseesofthepotentialfordifferentialtemperatureconditionstoaffecttheoperabilityof
safety-relatedpumps.Itisexpectedthatrecipientswillreviewtheinformationforapplicabilityto
theirfacilitiesandconsideractions,asappropriate,toavoidsimilarproblems.However, suggestionscontainedinthisinformationnoticearenotNRCrequirements;therefore,no
specificactionorwrittenresponseisrequired.DescriptionofCircumstancesThefollowingdescribestwoeventsthatappeartohavebeencausedbyinadequateengineeringdesignassessmentoftheeffectofdifferentialtemperaturesonsafety-related
pumps.ArkansasNuclearOne,Unit1(ANO-1)In1992,thelicenseeforANO-1implementedadesignchangetoreplacethecastironinboardandoutboardbearinghousingsonthelow-pressureinjection/decayheatremoval(LPI/DHR)
pumpswithstainlesssteelforimprovedservicewatercorrosionresistance.TheLPI/DHR
systemisdesignedtoremovedecayheatfromthecoreandsensibleheatfromthereactor
coolantsystem(RCS)duringthelaststagesofaplantcooldown.Italsoprovidesameansof
automaticallyinjectingboratedwaterintothereactorvesselforcoolingthecoreintheeventof
aloss-of-coolantaccidentduringpoweroperation.DuringtheSeptember1999refueling
outage,thelicenseeimplementedadesignchangetoincreasetheviscosityofthelubricatingoil
fortheLPI/DHRpumpbearingsinordertoreducewear.OnFebruary5,2000,ANO-1begancoolingdowntheplantinpreparationforenteringamaintenanceoutagetoinstallreplacementpartsonthe"D"reactorcoolantpumpanti-rotation
device.WhentheRCStemperaturehadbeenreducedto280Fandthepressurehadbeenreducedto240psig,the"A"LPI/DHRpumpwasplacedinservicefordecayheatremoval.
After52minutes,thelicenseewasforcedtosecurethe"A"LPI/DHRpumpwhentheinboard
bearingtemperaturereachedapproximately160F.Thelicenseethenplacedthe"B"LPI/DHRML003712586 IN2000-08Page2of4pumpinserviceforDHRbutstoppeditafter16minutesduetoahighinboardbearingtemperature.Thelicenseetestedbothpumpsbyrecirculatingwaterfromtheboratedwater
storagetankandnotedthatthebearingtemperaturesremainedstableatapproximately80F.Duringthistestthepumpedfluid,theboratedwater,wasatambienttemperature.Upon
switchingthe"B"pumpsuctionbacktotheRCS,thebearingtemperatureagainroseto
approximately160F.Inthisinstancethepumpedfluid,theRCSwater,wasatatemperatureofapproximately250F.OnFebruary6,2000,thelicenseechangedthe"A"LPI/DHRpumpbearingoilbacktotheoriginal(lowerviscosity)specification.Whenthe"A"LPI/DHRpumpwasplacedbackinthe
DHRmodeofoperation,thebearingtemperaturestabilizedat119F.ThelicenseethendeclaredtheLPI/DHRpumpoperablefortheDHRmodeonlyandproceededtocooldownthe
plant.Thelicenseethenchangedthe"B"LPI/DHRpumpbearingoilbacktooriginal
specification.But,unlikethe"A"pump,the"B"pumpagainhadtobeshutdownduetohigh
bearingtemperature.Inspectionofthe"B"pumpfollowingshutdownindicatedthattheinboard
bearinghadtobereplacedduetoabnormalwear.Furtherdetailswereprovidedbythe
licenseeinitsLicenseeEventReport(LER)50-313/2000-002-00datedMarch6,2000
(AccessionNo.ML003691450).BeaverValleyPowerStation,Unit1OnFebruary8,2000,thelicenseefortheBeaverValleyPowerStation,Unit1(thelicensee),wasperformingaroutinesurveillanceonthe"B"riverwaterpump.Thepumptrippedonover
currentprotectionafterapproximately3seconds.Afewhourslater,startupofthe"C"river
waterpumpwasattemptedanditalsotrippedafter3secondsbecauseofovercurrent
protection.Thelicenseedeterminedthattheovercurrenttripswerearesultofpumpbinding.Thecauseofthebindingwasthermalexpansionofthepumpshaftasaresultofatemperaturedifferential
betweentheriverwater(35degreesF)andanelevatedsealinjectionwatertemperature(70
degreesF).Theriverwaterpumpsealwaterwasbeingsuppliedbythenon-safetyrelated
filteredwatersystem.Atthetimeoftheevent,thefilteredwatersystemwasinanabnormal
configurationthatcreatedtheelevatedwatertemperature.Furtherdetailsonthiseventare
availableinLER50-334/2000-002-00datedMarch8,2000(AccessionNo.ML003692855),
LER50-334/2000-002-01datedApril27,2000(AccessionNo.ML003712023),andinNRC
InspectionReports05000334/2000-01datedMarch17,2000(AccessionNo.ML003693247),
and05000334/2000-02datedApril28,2000(AccessionNo.ML003709259).
DiscussionAtANO,theNRCperformedaspecialinspection(reportnumber50-313/00-04;50-368/00-04,AccessionNo.ML003708466)tofollowupontheeventswhichledtodeclaringbothUnit1 LPI/DHRpumpsinoperable.Theinspectorsconcludedthatthefailuretocompleteadequate
engineeringevaluationsforthereplacementofthecastironbearinghousingwithastainless
steelhousingandthechangeinlubricatingoilviscosityresultedintheinoperabilityofboth
IN2000-08Page3of4LPI/DHRpumps.Thechangesinthebearinghousingmaterialanduseofahigherviscosityoil,incombinationwithlowcoolingwatertemperatures(<42F),resultedinbothlowpressureinjection/decayheatremovalpumpsoperatingwithhighbearingtemperatures,whichrequired
thepumpstobesecured.FromJanuary28toFebruary5,2000,whenthecoolingwater
temperaturewas42Forless,bothlowpressureinjection/decayheatremovalpumpswerenotoperableastheycouldnotperformtheirintendedsafetyfunction.Thesedesigndeficiencies
werenotidentifiedbypostmodificationorsurveillancetesting.Testingperformedby
recirculatingwaterfromtheboratedwaterstoragetankdidnotduplicateactualoperational
conditionsbecausethepumpedfluid(fromtheboratedwaterstoragetank)wasatamuch
lowertemperaturethantheRCS.SubsequentinvestigationbytheANOlicenseeidentifiedotherpotentiallysusceptibleequipmentinbothunitsandtookappropriatecorrectiveactions.AttheBeaverValleyPowerStation,thelicenseedeterminedthatwhenwarmersealwaterisprovidedtoanidlepumpduringcoldriverwaterconditions,thewarmersealwatertravelsdown
thepumpshaftandincreasestheshafttemperature.Thepumpcasingisnotindirectcontact
withthesealwaterand,therefore,isnotaffectedbytheincreaseinsealwatertemperature.
Thistemperaturedifferentialresultedinelongationofthepumpshaft,impellercontactwiththe
pumpcasing,andeventualpumpbinding.Thesamewarmersealwatersuppliedtothepumps
whentheyareidleisalsosuppliedtothemwhentheyareoperating.However,theeffectof
havingwarmersealwatersuppliedtoanoperatingpumpwasnegligiblebecauseofthe
extremelylargevolumeofpumpedfluidactingasaheatsinkonthesmallvolumeofsealwater
passingthroughthepumpinnercolumn.Thelicenseealsodeterminedthatthefilteredwater
systemcouldintroduceacommon-modefailuretoallthreesafety-relatedriverwaterpumps.
Thefilteredwatersystemwassubsequentlyisolatedasasupplysourcetotheriverwater
pumpsandthepumpswereoperatedfromtheirsafetyrelatedsupply.Duringthisoperation,thelicenseeidentifiedaninadequacyinthedesignofthesafety-relatedsealwatersupplystrainers.Sinceoriginalplantoperationin1976,thenon-safety-related
filteredwatersystemhadbeentheprimarysupplytotheriverwaterpumpseals.However, duringoperationofthepumpsontheirsafety-relatedsupply,thesafety-relatedinlinestrainers
fouledduringhighsiltconditions.Safety-relatedpumpsareexpectedtooperateunderawiderangeofenvironmentalconditions.Thesetwoeventshighlighttheimportanceofassessingtheeffectsofdifferentialtemperatures
onsafety-relatedpumpoperability.Inaddition,theseeventshighlighttheimportanceofhaving
testprogramsthatincludesuitablequalificationtestingunderthemostadversedesign
conditions(e.g.,temperatureanddifferentialtemperature),whenthetestprogramisusedto
verifytheadequacyofaspecificdesignfeature(e.g.sealwatersupply).
IN2000-08Page4of4Thisinformationnoticerequiresnospecificactionorwrittenresponse.Ifyouhaveanyquestionsabouttheinformationinthisnotice,pleasecontactoneofthetechnicalcontacts
listedbelowortheappropriateOfficeofNuclearReactorRegulation(NRR)projectmanager./RA/LedyardB.Marsh,ChiefEventsAssessment,GenericCommunicationsandNon-PowerReactorsBranchDivisionofRegulatoryImprovementPrograms
OfficeofNuclearReactorRegulationTechnicalcontacts:CharlesD.Petrone,NRREricJ.Benner,NRR301-415-1027301-415-1171 E-mail:cdp@nrc.govE-mail:ejb1@nrc.govAttachment:ListofRecentlyIssuedNRCInformationNotices
IN2000-08Page4of4Thisinformationnoticerequiresnospecificactionorwrittenresponse.Ifyouhaveanyquestionsabouttheinformationinthisnotice,pleasecontactoneofthetechnicalcontacts
listedbelowortheappropriateOfficeofNuclearReactorRegulation(NRR)projectmanager./RA/LedyardB.Marsh,ChiefEventsAssessment,GenericCommunicationsandNon-PowerReactorsBranchDivisionofRegulatoryImprovementPrograms
OfficeofNuclearReactorRegulationTechnicalcontacts:CharlesD.Petrone,NRREricJ.Benner,NRR301-415-1027301-415-1171 E-mail:cdp@nrc.govE-mail:ejb1@nrc.govAttachment:ListofRecentlyIssuedNRCInformationNoticesDISTRIBUTION:REXBR/F Public*SeepreviousconcurrenceACCESSION#ML003712586TEMPLATE#052Toreceiveacopyofthisdocument,indicateintheboxC=Copyw/oattachment/enclosureE=Copywithattachment/enclosureN=NocopyOFFICEREXB:DRIPEREXB:DRIPETechEditorDLPM/LPD4ENAMECPetrone*EBenner*BCalure*MNolan*
DATE04/11/0004/11/0004/10/005/05/00OFFICEDLPM/LPD1DE/EMEBEREXB:DRIPEC:REXB:DRIPENAMEDCollins*DTerao*TKoshy*LMarsh
DATE4/19/0004/12/005/08/005/15/00OFFICIALRECORDCOPY
____________________________________________________________________________________OL=OperatingLicense
CP=ConstructionPermitAttachmentIN2000-08
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_____________________________________________________________________________________InformationDateof
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HealthRespiratorUserNotice:
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CertainSelf-Contained
BreathingApparatusAir
Cylinders4/10/2000Allholdersofoperatinglicensesfornuclearpowerreactors,non- powerreactors,andallfuelcycle
andmateriallicenseesrequiredto
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emergencyplan2000-06OffsitePowerVoltageInadequacies3/22/2000Allholdersofoperatinglicensesfornuclearpowerreactors, exceptthosewhohave
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andhavecertifiedthatfuelhas
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fromInattentiontoDetail3/06/2000Allmedicallicensees2000-041999EnforcementSanctionsforDeliberateViolationsof
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2)Powder Accumulation2/22/2000AllNRClicensedfuel-cycledconversion,enrichment,and
fabricationfacilities2000-01OperationalIssuesIdentifiedinBoilingWaterReactorTripand
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