ML17334B683

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Responds to GL 97-04, Assurance of Sufficient Net Positive Suction Head for ECC & Containment Heat Removal Pumps.
ML17334B683
Person / Time
Site: Cook  American Electric Power icon.png
Issue date: 01/30/1998
From: FITZPATRICK E
INDIANA MICHIGAN POWER CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
AEP:NRC:1280A, GL-97-04, GL-97-4, NUDOCS 9802120302
Download: ML17334B683 (10)


Text

~CATEGORY1REGULATORYINFORMATIONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:9802120302DOC.DATE:98/Ol/30NOTARIZED:YESDOCKETFACIL:50-315DonaldC.CookNuclearPowerPlant,Unit1,IndianaM0500031550-~16D'onaldC.CookNuclearPowerPlant,Unit2,IndianaM05000316AUTH.NAMEAUTHORAFFILIATIONFITZPATRICK,E.EIndianaMichiganPowerCo.RECIP.NAMERECIPIENTAFFILIATIONDocumentControlBranch(DocumentControlDesk)

SUBJECT:

SubmitsGL97-04,"AssuranceofSufficientNetPositiveSuctionHeadforECCEcContainmentHeatRemovalPumps."DISTRIBUTIONCODE:A076DCOPIESRECEIVED:L'VRENCLSIZE:TITLE:GL97-04AssuranceofSufficientNet>PositiveSuctionHeadForNOTES:Emerg~ERECIPIENTIDCODE/NAMEPD3-3PDCOPIESRECIPIENTLTTRENCLIDCODE/NAME11"HICKMAN,JCOPIESLTTRENCL110INTERNAL:LECENTENRRSSA/SRXBEXTERNAL:NOAC111.111NRR/DSSA/SCSBNRR/PD3-2NRCPDR112211D0UENNOTETOALL"RIDS"RECIPIENTS:PLEASEHELPUSTOREDUCEWASTE.TOHAVEYOURNAMEORORGANIZATIONREMOVEDFROMDISTRIBUTIONLISTSORREDUCETHENUMBEROFCOPIESRECEIVEDBYYOUORYOURORGANIZATION,CONTACTTHEDOCUMENTCONTROLDESK(DCD)ONEXTENSION415-2083TOTALNUMBEROFCOPIESREQUIRED:LTTR9ENCL9 a~ft,~i'4f,pVI' IndianaMichiganPowerCompany500CircleDriveBuchanan,Ml491071395January30,1998AEP:NRC:1280ADocketNos.:50-31550-316U.S.NuclearRegulatoryCommissionATTN:DocumentControlDeskWashington,D.C.20555-0001Gentlemen:DonaldC.CookNuclearPlantUnits1and2LICENSENOS.DPR-58ANDDPR-74REQUESTEDINFORMATION-GENERICLETTER(GL)97-04ASSURANCEOFSUFFICIENTNETPOSITIVESUCTIONHEADFOREMERGENCYCORECOOLINGANDCONTAINMENTHEATREMOVALPUMPSOnOctober7,1997,theNuclearRegulatoryCommission(NRC)issuedGL97-04,"AssuranceofSufficientNetPositiveSuctionHeadforEmergencyCoreCoolingandContainmentHeatRemovalPumps",indicatingthatadequatenetpositivesuctionheadmaynotbeavailabletotheemergencycorecoolingsystemandcontainmentspraypumpsunderalldesignbasisaccidentscenarios.TheattachmenttothislettercontainsourresponsetotheinformationrequestedinGL97-04."'.E.E.FitzpatrickVicePresident'rt,,SWORNTOANDSUBSCRIBEDBEFOREMEghTHIS~DAYOF~+~4,1998NotaryPublic//vlbAttachmentUNDAL8OEi.CKENotaryPublic,8errienCaunty,MlMyCommissionExpiresJanuary21,2001J.A.AbramsonA.B.BeachMDEQ-DW&RPDNRCResidentInspectorJ.R.Sampson9802i20302'st80i30PDRADQCK050003i5PPDRllllllllllllllllllllllllllllIlllllllll li"l ATTACHMENTTOAEP:NRC:1280AREQUESTEDINFORMATION-GENERICLETTER(97-04),ASSURANCEOFSUFFICIENTNETPOSITIVESUCTIONHEADFOREMERGENCYCORECOOLINGANDCONTAINMENTHEATREMOVALPUMPSa'pl%llh\'

AttachmenttoAEP:NRC:1280APage1Followingisourresponsetotheinformationrequestedingenericletter(GL)97-04,"AssuranceofSufficientNetPositiveSuctionHeadforEmergencyCoreCoolingandContainmentHeatRemovalPumps",datedOctober7,1997.GL97-04REVESTNO.1"SpecifythegeneralmethodologyusedtocalculatetheheadlossassociatedwiththeECCSsuctionstrainers."OURRESPONSETOREVESTNO.1Theemergencycorecoolingsystem(ECCS)suctionstrainersatCookNuclearPlantconsistofgratingandscreensattheinlettothecontainmentrecirculationsump.Thesumpdesignincludestwolayersofcoarsegratingatthesumpentrancethatsandwichasinglelayerof1/4"finemeshscreen.Thenetpositivesuctionhead(NPSH)calculationfortheECCSandcontainmentspray(CTS)pumpsassumesaheadlossof1ft.acrossthecontainmentrecirculationsumpataflowof15,600gpm.Thisheadlossrepresentslossesfromupstreamoftheouterlayerofgrating,throughthesump,andintothepipesatthesumpexit.Theassumedheadlossisbasedonempiricaldatafromsumpmodeltesting,plusconservatism.Ourcontainmentrecirculationsumpdesignwasmodeltestedduringthelate1970satAldenResearchLaboratorytostudyvortexingandairentrainment.TheresultsfromthemodeltestingweresubmittedtotheNRCinourletterAEP:NRC:00112,datedDecember20,1978.Aby-productfromthemodeltesting,whichincludedtestingforvarious"plateblockage"schemesatthesumpentrance,wasempiricalheadlossdataacrosstheentiresumpatminimumwaterlevel,elevation602'-10".Sumpentryscreenblockageofupto50%wasmodeled.Losscoefficientsweredeterminedforvarioustestschemes,andarerepresentedbytheequation:h~Cq=".y'2gwhere:Cghvgdimensionlesslosscoefficienttheheadlossinft.fluidvelocityatthesumpexitpipes32.2ft./sec.'osscoefficientdatafromtable10oftheAldenLaboratorytestreport,whenusedwiththeaboveequation,indicatedthatthehighestobservedheadlossacrossthesumpwas0.77ft.Maximumflowduringsumpmodeltestingwas15,400gpm,7,700gpmpersumpoutletpipe,whichcompareswelltoamaximumexpectedflowof15,600gpmpercurrentcalculations.Thisdifferenceinflowwasconsideredinsignificantindeterminingheadlossacrossthesumpinletandthroughthesump.Theas-modeledsumpdesignincludedasinglecoarsegratingandasinglefinemeshscreen.AldenLaboratoryalsoprovidedheadlossdataforlossesacrossthegratingandscreen.Becausethecurrentsumpentranceincludestwolayersofcoarsegrating,oneupstreamandonedownstreamofthefinemeshscreen,theheadlossacrossthegratingandscreenwascountedtwicetoconservativelyaccountforthesecondgrating.

IIAttachmenttoAEP:NRC:1280APage2Basedontheheadlossthroughthesumpof0.77ft.intheas-modeledconfiguration,andaheadlossof0.052ft.acrossthesecondgrating,thecurrentNPSHcalculationconservativelyassumesa1ft.headlossacrossthesump.Althoughthesumpheadlossdataaboveincludeslossesfromupstreamofthesumpentrancetoinsidethepipesatthesumpexit,entrancelossesatthesumpexitpipeswerealsocalculatedseparatelyandincludedintheNPSHcalculationsforconservatism.GL97-04REVESTNO.2"IdentifytherequiredNPSHandtheavailableNPSH."OURRESPONSETOREVESTNO.2Thenetpositivesuctionheadrequired(NPSHR)andnetpositivesuctionheadavailable(NPSHA)fortheresidualheatremoval(RHR)andCTSpumps,whichtakesuctiondirectlyfromthecontainmentrecirculationsump,areasfollows:~PumNPSHRNPSHARHRCTS20ft.abs9ft.abs29ft.abs31ft.absAsa"pointofinformation,theNPSHRandNPSHAforthesafetyinjection(SI)andcentrifugalcharging(CC)pumps,whichtakesuctionfromtheRHRpumpswhentheECCSisintherecirculationmodeofoperation,are:~PumSICCNPSHR13ft.abs17ft.absNPSHA122ft.abs48ft.absTheNPSHR,tabulatedabove,wasobtainedfromtheindividualECCSpumpperformancecurvesattheexpectedECCSpumpflow.AvailableNPSH,tabulatedabove,wascalculatedusingthegeneralmethodologydetai'led,below.Asindicated'in,ourresponsetoquestion.No.,l,,'head,lossof1'ft.'a'crossthesump'screhnwasas'sumedin,the.NPSH,calculationat15,600gpm.ThebasicequationforcalculatingNPSHis:NPSH=h,-h,+h-hfdfwhere:h,habsolutepressure,infeetoftheliquidbeingpumped,onthesurfaceoftherecirculationsumplevel,head,infeet,correspondingtothevaporpressureoftherecirculationsumpliquidatthetemperaturebeingpumped,staticheight,infeet,thattherecirculationsumpliquidlevelisaboveorbelowthepumpsuctioncenterlineorimpellereye,and AttachmenttoAEP:NRC:1280APage3h=allfrictionlosses,infeet,includingentrancelossesandfrictionlossesthroughpipe,valves,andfittings,etc.Additionaldetailsoneachoftheabovetermsareprovidedbelow.h,-Absolutepressureonthesurfaceoftherecirculationsumplevel.Thistermisthecontainmentpressureassumedintheanalysis.Becausenocreditistakenforcontainmentoverpressure,atmosphericpressureisusedastheliquid'sabsolutepressure.h,-Headcorrespondingtothevaporpressureoftherecirculationsumpliquidatthetemperaturebeingpumped.Thistermisafunctionofthetemperatureofthefluid.Themaximumexpectedrecirculationsumptemperatureof190'.isused.Thisconservativelyboundsbothunits.h-Staticheightthattherecirculationsumpliquidlevelisaboveorbelowthepumpsuctioncenterlineorimpellereye.Thistermistheminimumstaticheightoffluidabovethepumpcenterline.Aminimumsumpwaterlevelcorrespondingtoelevation602'-10"wasused,whichwasconfirmedviasumpmodeltestingtobealevelthatprecludesairentrainmentandvortexing.Sumpinventorycalculationsconfirmthatthislevelwillbesustainedforpostulatedaccidents.h-Allfrictionlossesincludingentrancelossesandfrictionlossesthroughpipe,valvesandfittings.ThisterminvolvessuctionlinelossesassociatedwiththeECCSpumpbeingevaluated.Theheadlossesconsideredinthistermarefrictionlossesbasedonpiperoughness,pipelength,velocityheadlosses,headlossassociatedwithsumpscreen,entrancelosses,andnumberortypeofvalvesandifittingsinthe,suctionpiping.i~w~,IiQL.97-04REVESTNO.'""Specifywhetherthecurrentdesign-basisNPSHanalysisdiffersfromthemostrecentanalysisreviewedandapprovedbytheNRCforwhichasafetyevaluationwasissued."OURRESPONSETOREVESTNO.3ThecurrentdesignbasisNPSHanalysisdiffersfromthemostrecentanalysissubmittedtotheNRCinthemannerinwhichtheRHRsystemwasanalyzed.ThemostrecentNPSHanalysissubmittedtotheNRCwasprovidedinresponsetoFSARchapter6.3,question212.29(unit2,appendixQ;amendment78,October1977).Question212.29consistedofthreeparts,oneofwhichwasspecifictotheNPSHanalysesfortheECCSpumps.ThisquestionrequesteddetaileddescriptionsoftheNPSHcalculationsfortheECCSpumpsduringpostulatedpostloss-of-coolantaccidentconditions,includingpertinentelevations,limitingpumpandvalvealignmentthatwouldprovidethesmallestNPSHmargin,pumpNPSHrequirements,justificationofthesumpwatertemperature,suctionlinehydrauliclosses,andresultant AttachmenttoAEP:NRC:1280APage4NPSHmargininaccordancewithregulatoryguide1.1.Aspartoftheresponsetothisquestion,acopyoftheNPSHcalculationwasincludedasanattachment.AreviewofthatattachmentindicatesthattheNPSHwascalculatedbasedonthefollowing.Watertemperature,1904F.Containmentpressure,oneatmosphere(absolute)Pumpsoperatingatmaximumflowrateasdeterminedbysystemresistancecalculationsassumingreactorcoolantsystempressureequalto0psigandallaffectedvalvesconsideredwideopen.ThesinglefailurethatwillresultinthelowestNPSHmarginisthefailureofoneRHRpumptooperate.Inthisinstance,theremainingRHRpumpwilloperateatarunoutcondition.Noreactorcoolantwaternoricebedmeltdownisusedtoestablishactivecontainmentsumpwaterinventory.TheNPSHAcalculationsutilizeonlythatportionoftherefuelingwaterstoragetank(RWST)inventorythathasbeenpumpedintothecontainmentpriortotheswitchoverofthefirstECCStrainswitch-overfromRWSTtotheactivecontainmentsump.RHRpumpdischargecrosstievalves,IMO-314andIM0-324,areopenallowingRHRflowfromonepumptoflowthroughbothRHRheatexchangers.Containmentrecirculationsumpdesignincludescoarsegratingatthesumpentranceandfinegrating,perforatedplate,inthesumpbackchamberjustupstxeamofthesumpoutletpipes.ThecurrentdesignbasisNPSHcalculationisbasedonthefollowing.\2.3'.'atertemperature,1904F.Containmentpressure,one,atmosphere(absolute)..IPumpsoperatingasdeterminedbysystemresistancecalculationsassumingreactorcoolantsystempressureequalto0psig,andECCSSIandCCvalvessetasrequiredbytechnicalspecifications.ThesinglefailureappliedisthefailureofoneRHRpumptooperate.Inthisinstance,theremainingRHRpumpwillsupplytwoSIpumpsandtwoCCpumpsthroughasingleRHRheatexchanger(see6below).Reactorcoolantwaterandicebedmeltdownisusedtoestablishactivecontainmentsumpwaterinventory.Thischangewasdeterminedtobeanunreviewedsafetyquestion.AlicenseamendmenthasbeenissuedinresponsetooursubmittalAEP:NRC:0900K,datedOctober8,1997.RHRpumpdischargecrosstievalvesareclosedasrequiredbyourprocedureOHP4023.ES-1.3,"TransfertoColdLegRecirculation".TheRHRpumpdischargecrosstievalvesarenormallyclosedtoprecludedead-headingofaweakerRHRpump.

AttachmenttoAEP:NRC:1280APage5ContainmentrecirculationsumpdesignasmodifiedtoincorporaterecommendationsfromsumpmodeltestingbyAldenResearchLaboratory.Modifiedsumpdesignincludestwolayersofgratingthatsandwichasinglelayeroffinemeshscreen,atthesumpentrance.Finegratingandperforatedplateinthesumpbackchamberwereremoved.Therefore,thecurrentdesignbasisNPSHanalysisdiffersfromthemostrecentanalysissubmittedtotheNRCasindicatedbythedifferencesbetweenitems3,4,5,6,and7above.GL97-04REVESTNO.4"Specifywhethercontainmentoverpressure(i.e.,containmentpressureabovethevaporpressureofthesumporsuppressionpoolfluid)wascreditedinthecalculationofavailableNPSH.Specifytheamountofoverpressureneededandtheminimumoverpressureavailable."OURRESPONSETOREVESTNO.4CreditwasnottakenforthecontainmentpressureindeterminingtheNPSHavailabletotheECCSpumps.ThecontainmentpressureusedindeterminingtheNPSHavailableisoneatmosphere,absolute.NooverpressureorminimumoverpressurewasusedindeterminingtheavailableNPSH.GL97-04REUESTNO.5"WhencontainmentoverpressureiscreditedinthecalculationofavailableNPSH,confirmthatanappropriatecontainmentpressureanalysiswasdonetoestablishtheminimumcontainmentpressure."OURRESPONSETOREVESTNO.5CreditisnottakenforcontainmentoverpressurepressureindeterminingtheNPSHavailabletotheECCSpumps.ThecontainmentpressureusedindeterminingtheNPSHavailableisoneatmosphere.'Itlll4