ML17335A223

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Submits Addl Info Re Relief Request for Third 10-yr Interval Pump in-service Test Plan.Proposed Alternative Is Being Submitted Because Code Requirements for Vibration Cannot Be Met Due to Containment Spray Pumps Being Tested
ML17335A223
Person / Time
Site: Cook  American Electric Power icon.png
Issue date: 09/04/1998
From: POWERS R P
INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
AEP:NRC:0969BM, AEP:NRC:969BM, NUDOCS 9809160029
Download: ML17335A223 (20)


Text

CATEGORY1.REGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)r'CCESSION NBR:9809160029 DOC.DATE:

98/09/04NOTARIZED:

NODOCKETFACIL:50-315 DonaldC.CookNuclearPowerPlant,Unit1,IndianaM0500031550-316DonaldC.CookNuclearPower.Plant,Unit2,XndianaM05000316 AUTH.NAMEAUTHORAFFILIATION POWERS,R.P.

IndianaMichiganPowerCo.(formerly Indiana&.MichiganEleRECIP.NAME RECIPIENT AFFILIATION RecordsManagement Branch(Document ControlDesk)

SUBJECT:

Submitsaddiinforereliefrequestforthird10-Yrintervalpumpin-service testplan.Proposedalternative beingsubmitted becausecoderequirements forvibration cannotbemetduetocontainment spraypumpsbeingtested.DISTRIBUTION CODE:A047DCOPIESRECEIVED:LTR ENCL'SIZE:TITLE:ORSubmittal:

Inservice/Testing/Relief fromASMECode-GL-89-04NOTES:ATRECIPIENT IDCODE/NAME PD3-3LASTANG,JINTERNAL:

AEOD/SPD/RAB NRR/DE/ECGB OGC/HDS3'ES/DET/EMMEB COPIESLTTRENCL111111111011RECIPIENT IDCODE/NAME PD3-3PDFIECENUDOCS-ABSTRACT RES/DET/EIB COPIESLTTRENCL11111111EXTERNAL:

LITCOANDERSONNRCPDR1111NOAC11DNNOTETOALLnRIDSnRECIPIENTS PLEASEHELPUSTOREDUCEWASTE.TOHAVEYOURNAMEORORGANIZATION REMOVEDFROMDISTRIBUTION LISTSORREDUCETHENUMBEROFCOPIESRECEIVEDBYYOUORYOURORGANIZATION, CONTACTTHEDOCUMENTCONTROLDESK(DCD)ONEXTENSION 415-2083TOTALNUMBEROFCOPIESREQUIRED:

LTTR13ENCL12 IndianaMichigan~PowerCompany500CircleDriveBuchanan, Ml491071373INOIAiMNICHIGAHIrWMSeptember 4,1998AEP:NRC:0969BM 10CFR50.55aDocketNos.:50-31550-316U.S.NuclearRegulatory Commission ATTN:DocumentControlDeskMailStop0-Pl-17Washington, D.C.20555-0001 Gentlemen:

DonaldC.CookNuclearPlantUnits1and2RELIEFREQUESTFORTHETHIRDTENYEARINTERVALPUMPIN-SERVICE TESTPLANADDITIONAL INFORMATION Thepurposeofthisletteristoproposeanalternative totherequirements ofASMESectionXI,OMa-1988, Part6,paragraph 5.2,Table34forthecontainment spray(CTS)pumps.This~alternative isbeingsubmitted undertheprovisions of10CFR50.55a(a)(3)(ii),

"compliance withthespecified requirements ofthissectionwouldresultinhardshiporunusualdifficulty withoutacompensating increaseinthelevelofqualityorsafety".Theproposedalternative isbeingsubmitted becausethecoderequirements forvibration cannotbemetduetotheCTSpumpsbeingtestedatlowflowconditions andbecauseofthepumps'esign.

Ouroriginalreliefrequestsforthethirdtenyearintervalweresubmitted byletterAEP:NRC:0969AM, datedJune12,1996.ByletterdatedMay27,1997,theNRCdeniedthereliefrequestforthecontainment spraypumps,statingthatinsufficient information wasprovidedintheoriginalrequest.OnJanuary13,1998,andFebruary9,1998,discussions wereheldwithmembersofyourstaffregarding testingoftheseCTSpumps,andarequestforinterimreliefwassubmitted viaAEP:NRC:0969BJ, datedMarch3,1998.Theinterimreliefwasrequested whileamodification wasmadetooursparepumpatthemanufacturer's servicecenter.Themodification tothepumpwasmadeinanattempttoreducethepump'svibration levelsatlowflowsatwhichthevibration dataaretaken.Themodifications, however,didnotsignificantly reducethevibration levelsatlowflow,andpermanent reliefisbeingrequested.

Thepermanent reliefrequestiscontained intheattachment tothisletter.Thereliefrequestcontainstheadditional information theNRCrequested intheMay27,1997,denial.9809160029',980904 PDRADOCK05000315P'DR U.S.NuclearRegulatory Commission Page2AEP:NRC:0969BM Expedited reviewofthisreliefrequestisrequested becausethisreliefisnecessary forrestartofourunits.Sincerely, REPEPowersVicePresident

/jmcAttachments ceJ.A.AbramsonJ.L.Caldwell, w/attachments MDEQ-DW&RPDNRCResidentInspector, w/attachments J.R.Sampson,w/attachments U.S.NuclearRegulatory Commission Page3AEP:NRC:0969BM bc:T.P.Beilman,w/attachments E.R.Eckstein/D.

R.Hafer/K.R.BakerJ.J.EutoFOLIO,w/attachments E.HinesJ.B.Kingseed/M.

S.Ackerman/G.

P.Arent/M.J.GumnsF.R.Pisarsky/B.

B.BradleyJ.F.Stang,Jr.,NRC-Washington, DC,w/attachments ATTACHMENT TOAEP:NRC:0969BM CONTAINMENT SPRAYPUMPRELIEFREQUEST Attachment toAEP:NRC:0969BM Page1~Summa'he CookNuclearPlanthasfourcontainment spray(CTS)pumpsofanoldervintagethatmetthe1983codeedition,butareunabletoconformwiththevibration requirements imposedbythecodeupgradeforthethirdten-yearin-service testinterval.

Theirinability toconformisnotduetodegradedperformance, butratheraconsequence oftheiroriginaldesignandtheirbeingtestedatlowflowconditions.

Amodification wasperformed tothespareassemblyinanefforttoreducelowflowvibrations towithinlimitsspecified, bythecode.Extensive testingofthepre-andpost-modification designwasperformed onthespareCTSpumpwiththeassistance ofthepump'smanufacturer.

Theseeffortsrevealedthatvibrations encountered onpumpsinstalled inthefieldhavesimilarvibration signatures tothesparepumpwhichhadnopreviousruntimeandwasthoroughly inspected priortotesting.Thevibrations experienced weredetermined tobearesultofimpellervanepassduringlowflowconditions.

Thisvibration wasinversely proportional toflowrate,withvibrations decreasing toacceptable limitsatthepump'sdesignflowrating.Althoughsomereduction inpumpvibrations wasachieved, therevisedacceptance limitswerenotmet.Basedontestingperformed itwasconcluded thatfullcompliance withthecodewouldrequireeitheracompletenewtestcircuitcapableofaccommodating fullflow,oraredesigned rotatingelement(e.g.fivevaneimpeller),

whichwouldreducethevanepassfrequency vibration.

Timetoimplement eitheroneoftheseoptionshasbeenestimated atsixtotenmonths.Consequently, theirinstallation wouldresultinasignificant hardshipwithoutacompensating increasein,safety.Therefore, analternate monitoring methodisproposedtomeettheintentofthecode,detection ofpumpdegradation, andtoprovidereasonable assurance ofanacceptable levelofqualityandsafety.Thealternate surveillance specified tomonitorthesafeoperation ofthisequipment adoptsanapproachtoanalyzeavibration signature, orspectrum.

Insteadofanoverallaccumulative

approach, thevibration signature willbedividedintonarrowbandsoffrequency suchthatspecificformsofincipient degradation canbedetected.

Discussions withthedirectoroftheVibration Institute, membersofASME/ANSI 0&Mworkinggroupforin-service testing,thepumpmanufacturer, andpersonnel fromothernuclearutilities confirmthatspectralanalysisisanacceptable industrypracticeforpredictive maintenance onrotatingmachinery.

Attachment toAEP:NRC:0969BM Page2lnadditiontothealternate testingspecified intheattachedreliefrequest,predictive maintenance, suchasinfraredthermography ofmotorbearingsandspectralmonitoring onthepumpcasings,willbeemployed.

Althoughnotpartofthereliefrequest,theseadditional effortswillfurtherenhancemonitoring oftheCTSpumps.REQUESTNO.1RELIEFREQUESTTHIRDTEN-YEARINTERVALPUMPZN-SERVICE TESTPLANTITLE:Containment SprayPumpVibration LimitsUNITAPPLICABILITY:

Units1and2PUMPNAME:Containment SprayPUMPNUMBER(S):PP-009SYSTEM:Containment Spray(CTS)FLOWDIAGRAM:5144ASMECLASS:2PUMPFUNCTION:

Providecoolingwaterflowtocontainment atmosphere inaLOCAorsteamline break.RELIEFTYPE:ProposedAlternative spraytheASMECODETESTREQUIREMENTS

REFERENCE:

OMa-1988, Part6;paragraph 5.2TestProcedure andtheRangesforVibration TestParameters showninTable3a.CODEREQUIREMENT DESCRIPTION:

Forcentrifugal pumpsrunningat2600rpm,whereV,isthereferenced broadbandunfiltered vibration measurement; Acceptable rangeat52.5V,Alertrange>2.5V,to6V,or>0.325,in/secRequiredactionrange>6V,or>0.70in/secBASISFORCODEALTERNATIVE:

TheCTSpumpsinstalled atCookNuclearPlantvibrateinexcessoftherequiredactionlevelspecified withinTable3aofOMa-1988.Thisisnotduetodegradedperformance, butratherequipment designandthelimitedflowachievable duringsurveillance testing.Baselinetestingofasparepumpassemblyconfirmed thatthevibration decreases withincreasing flow,towithinacceptable limits,asshowninfigure1.TheCTSpumpsareasinglestageunitmountedvertically.

Thepumpshavedualsuctioninadoublevolutecasingequippedwithanimpellerwithanevennumber(4)ofvanes.Theradialclearance "GapB"betweentheimpeller's vanesandeachvolutelipissmall.Thepipingconfiguration onlyallowsthesepumpstobetestedatlowflow,about25%oftheirbestefficiency point.Theresultant flowvectors,whichrepresent fluidleavingthetipofeachvane,arenotinlinewitheithervolute.

Attachment toAEP:NRC:0969BM Page3Consequently, hydraulic shockwavesdevelopatthevanepassfrequency of4timestherunningspeed,or119.38Hz(-7200CPM),asshowninbothfigures2and3.Inanefforttocomplywiththenewcodevibration requirements, amodification wasmadetoourspareassemblyatthepumpmanufacturer's servicecenter.Thisconsisted ofmaximizing the"GapB"clearance bycuttingbackeachcasingdischarge volute.Theobjective wastoreducetheoverallvibration atlowflowtoanacceptable levelwithoutaffecting thehydraulic performance ofthepump.Pre-andpost-modification testresultsareshowninfigures4and5.Figure4illustrates thatthepumphydraulic performance atthedesignflowwasnotaffected.

However,figure5illustrates lessthan1/3ofthedesiredvibration improvement wasachievedataflowrateequivalent totheplant'stestcircuit.Vibration atthedesignflowof3200gpmwasessentially unchanged, remaining withinacceptable limits.Basedonasfoundtestingofthesparepumpassembly, modifications andsubsequent testingresults,itwasconcluded thatliteralcompliance withthenewcodewouldrequireoneofthefollowing options:1)Acompletenewtestcircuittoaccommodate amuchhigherflowrate.2)Adifferent rotatingelementforthepump(e.g.fivevane),whichshouldreducethevanepassfrequency andoverallvibration.

Thefirstoptionmustprovideapproximately 1500gpmadditional flowcapacity, accountforpumpheatgenerated duringthetest,andmeettheoriginaldesignbasisrequirement thattheCTSdischarge headerbemaintained dryfromthetopofbothCTSsprayheatexchangers allthewayintocontainment.

Therearetwomethodstoaccomplish thisoption:A)Toprovidetheflowcapacityandheatremovalcapability withoutfillingtheCTSheatexchanger wouldrequireapproximately 500feetoflargeborepipeperunittorecirculate thewaterfromtherefueling waterstoragetank(RWST).TheroutingofthispipebetweentheRWSTlocatedoutsideintheyard,andeachpumplocatedinthebasementoftheauxiliary

building, wouldencounter numerousstructural interferences, orB)UseoftheCTSheatexchanger wouldsupportanalternate routecontained entirelywithintheauxiliary building.

However,thisroutewouldrequireadditionofseveralisolation valves,approximately 150feetoflargeborepipingperunit,andadditional ventingcapability.

Itwouldlikelyalsorequireacoderelieftoperformthesurveillance inmode5,becauseofapotential forentraining theairpresentintheCTSdischarge

header, Attachment toAEP:NRC:0969BM Page4Thesecondoptionistodesignandmanufacture anewimpeller.

Themanufacturer doesnotcurrently haveafivevaneimpellerdesignedforthisapplication, thus,thiswouldrequireextensive development andtesting.Thiswouldaffectthehydraulic performance ofthemachines, andcouldrequirefullflowtestingoftheinstalled pumpstovalidatethedesignchange.Timerequiredtoimplement anyofthepreviously described optionshasbeenestimated atsixtotenmonths.Consequently, theirinstallation wouldresultinasignificant hardshipwithoutacompensating increaseinsafety.Therefore, alternative monitoring isproposedtomeettheintentofthecode,andtoassureanacceptable levelofqualityandsafety.PROPOSEDALTERNATIVE TESTING:Theproposedalternative testingistoperformspectralmonitoring andanalysisoverthefrequency rangespecified inASMEOMa-1988, Part6.Analysisistobeperformed onallfrequencies contained inthefrequency range,alarmingtobeperformed onthefrequencies ofdegradation identified below:~Fundamental TrainFrequency (FTF)~BallSpinFrequency (BSF)~2TimesBallSpinFrequency (2XBSF)~BearingPassOuterRaceFrequency (BPOR)~BearingPassInnerRaceFrequency (BPIR)Thefrequencies forestablishing thealarmsarecontained withinthefollowing tables,including AlertandActionalarmlevels.Thealertandactionalarmlevelswillbebasedonthemaximumpeakvalueofdegradation frequencies contained withineachbandofthebaselinespectralmeasurement.

Bandswhichcontainnodistinctdegradation frequency shallbealarmedusingtheproductof2.5timesand6timesthemaximumpeakvalueofthebaselinespectralmeasurement inaccordance withtable3.aofASMEOMa-1988Part6.

Attachment toAEP:NRC:0969BM Page5DeradationItemFTFBSF2XBSFBPORBPIROutboardMotorBearingFreuenc(Hz)11.51362.475124.9592.106145.83InboardMotorBearingFreuenc(Hz)12.20980.146160.29122.09175.47Alertlevelsperalarmbandnottoexceed0.325ipswithaminimumalarmsettingof0.03ipseActionlevelsperalarmbandnottoexceed0.70ipswithaminimumalarmsettingof0.06ips.Alarmbandsaresettoincludethosefrequencies ofdegradation asfollows:BandMinimumFrequency (Hz)9.8214.8860.99121200600MaximumFrequency (Hz)14.5859.50116.032006001000Itisimportant tonotethattheabovealarmbandscoverallbut6.76Hzofthecoderequiredfrequency range.Those6.76Hznotalarmedincludeonlyvanepass'andlinefrequencies notrelatedtomechanical degradation.

Although6.76Hzofthefrequency rangeisnotalarmed,analysiswillbeperformed onfrequencies withineachunalarmed band.Eachbandischosentoprovidealarmcapability forspecificdegradation frequencies asshownbelow.BandOutboardBearingFTFN/AFTFN/AInboardBearingN/ARPMMachineBSF,BPOR2xBSF,BPIRN/AN/ABSF2xBSF,BPOR,BPIRN/AN/AN/AN/AN/AN/ABands5and6aresettoindicatemultiplesofafundamental defectfrequency, andarenotsettolookforfrequencies ofdegradation thatonlyoccurwithinthosebands.

Attachment toAEP:NRC:0969BM Page6BASISFORCONCLUDING ALTERNATIVE TESTINGYIELDSACCEPTABLE LEVELSOFQUALITYANDSAFETY:Toconfirmthatvibration atvanepassisnotanoperational concernforthesepumps,theplant'sspareassemblywassenttothemanufacturer's facilityforflowlooptesting.Thesparepumphasneverbeeninstalled ortestedin-situ;therefore, itservedasabaselinetojudgehowthiskindofpumpperformswithnoelapsedruntime.CookNuclearPlantpersonnel andtheplant'svibration equipment wereusedduringtestingtoeliminate variables whencomparing testresultstodatacollected ontheinstalled pumps.Xnaddition, aninternalpumpinspection wasperformed verifying allcriticaldimensions tobewithinacceptable tolerances.

Figure2showsthevibration spectrumforthesparemachineasreceivedbythemanufacturer, beforethevolutelipmodification wasperformed.

Thissignature wastakenwhileoperating at733gpm,whichcloselyapproximates thetestconditions attheplant.Thespectrumillustrates thedominance vanepassfrequency hasovertheentirespectrum, withnoevidenceofdegradation atanyotherfrequency.

Figure3isarecentvibration spectrumfortheunit1eastCTSpumptakenduringanin-service test,performed afterroughly22yearsofservice.ThisspectralplotistypicalofthedataobtainedfortheotherCTSpumpsinstalled attheplant.Figures2and3arevirtually identical, confirming thatthevibration component occurring atvanepassfrequency isanexpectedconsequence ofpumpinternaldesignoperating atthein-service testflowrate,andnotanindication ofpumpdegradation.

Fullflowtestingofthesparepumpalsoverifiedthatasflowrateisincreased closertothepump'sbestefficiency point,overallvibration andvanepassfrequency decreasetolevelswellbelowthecodealertvalue.Therefore, overallvibration atflowratesexpectedduringadesignbasisaccidentsatisfycoderequirements (Figure1).Thepumpmanufacturer hasindicated thatvibration occurring atvanepassfrequency doesnotrepresent degradation, norwouldtherebeanymechanical defectsproducedbyoperating atlowflowconditions forshortperiodsoftime,suchasperiodicplantin-'ervice tests.Toconfirmthisassertion, thefourCTSpumpsinstalled attheplantwillbedisassembled andnondestructively examinedforsignsofdegradation priortorestart.Eachpumpmotorwillalsobedisassembled andinspected to'nsureitsbearingshavenotdegraded.

Theseinspections willprovidereasonable assurance thatquarterly testsperformed atlowflowhavenotcauseddegradation andwillestablish anacceptable baselinefortrendingfutureperformance usingtheproposedalternative methods.

Attachment toAEP:NRC:0969BM Page7Vibration monitoring isintendedtodetectchangesinamachine's mechanical performance.

Thecodecurrently requiresabroadbandunfiltered measurement from1/3minimumpumprunningspeeduptoatleast1000Hz.Thistypeofbroadbandmeasurement providesanoverallnumberindicative ofenergycontained withinfrequency range.Itdoesnotindicatethatadiscreetfrequency responsehaschangedand,therefore, cannotprecisely identifywhatformofdegradation maybeincipient.

Tobemoreeffective, vibration monitoring shoulddetectdeviations atdiscreetfrequencies.

Toprovideahigherdegreeofassurance thatnodegradation isoccurring, spectralmonitoring willbeperformed toidentifychangesindiscreetdegradation frequencies.

Spectralmonitoring iscapableofdetermining whichfrequency,-

ifany,hasdeviatedfrombaseline.

Analysisofspectralmeasurements allowsforidentification ofdiscreetfrequencies indicative ofmechanical degradation.

Identification ofthosediscreetdegradation frequencies allowsmoreaccuratemechanical performance

analysis, andadditional diagnostics arenottypically requiredtoidentifyrootcause.Basedontheabilityofthealternative testingtoidentifyspecificdegradation types,andthatunalarmed frequencies willbeanalyzed, itisconcluded thattheproposedalternative testingprovidesanacceptable levelofqualityandsafety.

Attachment toAEP:NRC:0969BM Page8FigUre1:Vibration AffectedByFlow1.20.8~~>06-.O0I>0.4.Readingsatlowerbearingperpendicular toshaffparallel:with pumpsuction/discharge nozzles(2V)0.20100015002000250030003500400045005000Flow(gpm)

+OverallAsFoundHVanePassAsFound t

Attachment toAEP:NRC:0969BM Page9Figure2:Sparepumponminiflowbeforelipperpendicular toshaftandparallelnozzles(2V).cutatlowerbearingwithsuction/discharge VOTOP444g7200CDIRT~,III2xVohtPSIO>

I~IIIFigure3:Unit1EastCTSonminiflowatlowerbearingperpendicular toshaftandparallelwithsuction/discharge nozzles(2V)measuredon01/25/98.

VOTOPOOLSIIJI2XVihOP4$4IizMz

Attachment toAEP:NRC:0969BM Page10Figure4:Hydraulics AffectedByLipCut600550-500-..=K450400500150025003500I45005500+AsFoundoPostLipCutFlow(gpm}

Attachment toAEP:NRC:0969BM Page11Figure5:Vibration AffectedByLipCut1.20.8VlCL0.6O0.Rea'din'gs atlower.bearihg':p'er'pendlcular toshaft:-:;.'ai allelwith'-pump suetionld1scharge

'noziles(2V)--,0.4-'.2500100015002000250030003500400045005000Flow(gpm)+OverallAsFoundQVanePassAsFound40verallAfterLipCutXVanePassAfterLipCut