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{{#Wiki_filter:CATEGORY1. | {{#Wiki_filter: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:== | ==SUBJECT:== | ||
Submitsaddiinforereliefrequestforthird10-Yrintervalpumpin- | 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:== | ==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}} |
Revision as of 07:09, 29 June 2018
ML17335A223 | |
Person / Time | |
---|---|
Site: | Cook |
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