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

~CATEGORY1REGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9802120302 DOC.DATE:

98/Ol/30NOTARIZED:

YESDOCKETFACIL:50-315 DonaldC.CookNuclearPowerPlant,Unit1,IndianaM0500031550-~16D'onaldC.CookNuclearPowerPlant,Unit2,IndianaM05000316AUTH.NAMEAUTHORAFFILIATION FITZPATRICK,E.E IndianaMichiganPowerCo.RECIP.NAME RECIPIENT AFFILIATION DocumentControlBranch(Document ControlDesk)

SUBJECT:

SubmitsGL97-04,"Assurance ofSufficient NetPositiveSuctionHeadforECCEcContainment HeatRemovalPumps."DISTRIBUTION CODE:A076DCOPIESRECEIVED:L'VR ENCLSIZE:TITLE:GL97-04Assurance ofSufficient Net>Positive SuctionHeadForNOTES:Emerg~ERECIPIENT IDCODE/NAME PD3-3PDCOPIESRECIPIENT LTTRENCLIDCODE/NAME 11"HICKMAN,J COPIESLTTRENCL110INTERNAL:

LECENTENRRSSA/SRXBEXTERNAL:

NOAC111.111NRR/DSSA/SCSB NRR/PD3-2 NRCPDR112211D0UENNOTETOALL"RIDS"RECIPIENTS:

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

LTTR9ENCL9 a~ft,~i'4f,pVI' IndianaMichiganPowerCompany500CircleDriveBuchanan, Ml491071395 January30,1998AEP:NRC:1280ADocketNos.:50-31550-316U.S.NuclearRegulatory Commission ATTN:DocumentControlDeskWashington, D.C.20555-0001 Gentlemen:

DonaldC.CookNuclearPlantUnits1and2LICENSENOS.DPR-58ANDDPR-74REQUESTED INFORMATION

-GENERICLETTER(GL)97-04ASSURANCE OFSUFFICIENT NETPOSITIVESUCTIONHEADFOREMERGENCY CORECOOLINGANDCONTAINMENT HEATREMOVALPUMPSOnOctober7,1997,theNuclearRegulatory Commission (NRC)issuedGL97-04,"Assurance ofSufficient NetPositiveSuctionHeadforEmergency CoreCoolingandContainment HeatRemovalPumps",indicating thatadequatenetpositivesuctionheadmaynotbeavailable totheemergency corecoolingsystemandcontainment spraypumpsunderalldesignbasisaccidentscenarios.

Theattachment tothislettercontainsourresponsetotheinformation requested inGL97-04."'.E.E.Fitzpatrick VicePresident

'rt,,SWORNTOANDSUBSCRIBED BEFOREMEghTHIS~DAYOF~+~4,1998NotaryPublic//vlbAttachment UNDAL8OEi.CKENotaryPublic,8errienCaunty,MlMyCommission ExpiresJanuary21,2001J.A.AbramsonA.B.BeachMDEQ-DW&RPDNRCResidentInspector J.R.Sampson9802i20302'st80i30 PDRADQCK050003i5PPDRllllllllllllllllllllllllllllIll lllllll li"l ATTACHMENT TOAEP:NRC:1280A REQUESTED INFORMATION

-GENERICLETTER(97-04),ASSURANCE OFSUFFICIENT NETPOSITIVESUCTIONHEADFOREMERGENCY CORECOOLINGANDCONTAINMENT HEATREMOVALPUMPSa'pl%llh\'

Attachment toAEP:NRC:1280A Page1Following isourresponsetotheinformation requested ingenericletter(GL)97-04,"Assurance ofSufficient NetPositiveSuctionHeadforEmergency CoreCoolingandContainment HeatRemovalPumps",datedOctober7,1997.GL97-04REVESTNO.1"Specifythegeneralmethodology usedtocalculate theheadlossassociated withtheECCSsuctionstrainers."

OURRESPONSETOREVESTNO.1Theemergency corecoolingsystem(ECCS)suctionstrainers atCookNuclearPlantconsistofgratingandscreensattheinlettothecontainment recirculation sump.Thesumpdesignincludestwolayersofcoarsegratingatthesumpentrancethatsandwichasinglelayerof1/4"finemeshscreen.Thenetpositivesuctionhead(NPSH)calculation fortheECCSandcontainment spray(CTS)pumpsassumesaheadlossof1ft.acrossthecontainment recirculation sumpataflowof15,600gpm.Thisheadlossrepresents lossesfromupstreamoftheouterlayerofgrating,throughthesump,andintothepipesatthesumpexit.Theassumedheadlossisbasedonempirical datafromsumpmodeltesting,plusconservatism.

Ourcontainment recirculation sumpdesignwasmodeltestedduringthelate1970satAldenResearchLaboratory tostudyvortexing andairentrainment.

Theresultsfromthemodeltestingweresubmitted totheNRCinourletterAEP:NRC:00112, datedDecember20,1978.Aby-product fromthemodeltesting,whichincludedtestingforvarious"plateblockage" schemesatthesumpentrance, wasempirical headlossdataacrosstheentiresumpatminimumwaterlevel,elevation 602'-10".

Sumpentryscreenblockageofupto50%wasmodeled.Losscoefficients weredetermined forvarioustestschemes,andarerepresented bytheequation:

h~Cq=".y'2gwhere:Cghvgdimensionless losscoefficient theheadlossinft.fluidvelocityatthesumpexitpipes32.2ft./sec.'oss coefficient datafromtable10oftheAldenLaboratory testreport,whenusedwiththeaboveequation, indicated thatthehighestobservedheadlossacrossthesumpwas0.77ft.Maximumflowduringsumpmodeltestingwas15,400gpm,7,700gpmpersumpoutletpipe,whichcompareswelltoamaximumexpectedflowof15,600gpmpercurrentcalculations.

Thisdifference inflowwasconsidered insignificant indetermining headlossacrossthesumpinletandthroughthesump.Theas-modeled sumpdesignincludedasinglecoarsegratingandasinglefinemeshscreen.AldenLaboratory alsoprovidedheadlossdataforlossesacrossthegratingandscreen.Becausethecurrentsumpentranceincludestwolayersofcoarsegrating,oneupstreamandonedownstream ofthefinemeshscreen,theheadlossacrossthegratingandscreenwascountedtwicetoconservatively accountforthesecondgrating.

IIAttachment toAEP:NRC:1280A Page2Basedontheheadlossthroughthesumpof0.77ft.intheas-modeledconfiguration, andaheadlossof0.052ft.acrossthesecondgrating,thecurrentNPSHcalculation conservatively assumesa1ft.headlossacrossthesump.Althoughthesumpheadlossdataaboveincludeslossesfromupstreamofthesumpentrancetoinsidethepipesatthesumpexit,entrancelossesatthesumpexitpipeswerealsocalculated separately andincludedintheNPSHcalculations forconservatism.

GL97-04REVESTNO.2"Identify therequiredNPSHandtheavailable NPSH."OURRESPONSETOREVESTNO.2Thenetpositivesuctionheadrequired(NPSHR)andnetpositivesuctionheadavailable (NPSHA)fortheresidualheatremoval(RHR)andCTSpumps,whichtakesuctiondirectlyfromthecontainment recirculation sump,areasfollows:~PumNPSHRNPSHARHRCTS20ft.abs9ft.abs29ft.abs31ft.absAsa"pointofinformation, theNPSHRandNPSHAforthesafetyinjection (SI)andcentrifugal charging(CC)pumps,whichtakesuctionfromtheRHRpumpswhentheECCSisintherecirculation modeofoperation, are:~PumSICCNPSHR13ft.abs17ft.absNPSHA122ft.abs48ft.absTheNPSHR,tabulated above,wasobtainedfromtheindividual ECCSpumpperformance curvesattheexpectedECCSpumpflow.Available NPSH,tabulated above,wascalculated usingthegeneralmethodology detai'led, below.Asindicated

'in,ourresponsetoquestion.

No.,l,,'head,lossof1'ft.'a'cross thesump'screhnwasas'sumedin,the.NPSH,calculation at15,600gpm.Thebasicequationforcalculating NPSHis:NPSH=h,-h,+h-hfdfwhere:h,habsolutepressure, infeetoftheliquidbeingpumped,onthesurfaceoftherecirculation sumplevel,head,infeet,corresponding tothevaporpressureoftherecirculation sumpliquidatthetemperature beingpumped,staticheight,infeet,thattherecirculation sumpliquidlevelisaboveorbelowthepumpsuctioncenterline orimpellereye,and Attachment toAEP:NRC:1280A Page3h=allfrictionlosses,infeet,including entrancelossesandfrictionlossesthroughpipe,valves,andfittings, etc.Additional detailsoneachoftheabovetermsareprovidedbelow.h,-Absolutepressureonthesurfaceoftherecirculation sumplevel.Thistermisthecontainment pressureassumedintheanalysis.

Becausenocreditistakenforcontainment overpressure, atmospheric pressureisusedastheliquid'sabsolutepressure.

h,-Headcorresponding tothevaporpressureoftherecirculation sumpliquidatthetemperature beingpumped.Thistermisafunctionofthetemperature ofthefluid.Themaximumexpectedrecirculation sumptemperature of190'.isused.Thisconservatively boundsbothunits.h-Staticheightthattherecirculation sumpliquidlevelisaboveorbelowthepumpsuctioncenterline orimpellereye.Thistermistheminimumstaticheightoffluidabovethepumpcenterline.

Aminimumsumpwaterlevelcorresponding toelevation 602'-10"wasused,whichwasconfirmed viasumpmodeltestingtobealevelthatprecludes airentrainment andvortexing.

Sumpinventory calculations confirmthatthislevelwillbesustained forpostulated accidents.

h-Allfrictionlossesincluding entrancelossesandfrictionlossesthroughpipe,valvesandfittings.

Thisterminvolvessuctionlinelossesassociated withtheECCSpumpbeingevaluated.

Theheadlossesconsidered inthistermarefrictionlossesbasedonpiperoughness, pipelength,velocityheadlosses,headlossassociated withsumpscreen,entrancelosses,andnumberortypeofvalvesandifittings inthe,suctionpiping.i~w~,IiQL.97-04REVESTNO.'""Specifywhetherthecurrentdesign-basis NPSHanalysisdiffersfromthemostrecentanalysisreviewedandapprovedbytheNRCforwhichasafetyevaluation wasissued."OURRESPONSETOREVESTNO.3ThecurrentdesignbasisNPSHanalysisdiffersfromthemostrecentanalysissubmitted totheNRCinthemannerinwhichtheRHRsystemwasanalyzed.

ThemostrecentNPSHanalysissubmitted totheNRCwasprovidedinresponsetoFSARchapter6.3,question212.29(unit2,appendixQ;amendment 78,October1977).Question212.29consisted ofthreeparts,oneofwhichwasspecifictotheNPSHanalysesfortheECCSpumps.Thisquestionrequested detaileddescriptions oftheNPSHcalculations fortheECCSpumpsduringpostulated postloss-of-coolantaccidentconditions, including pertinent elevations, limitingpumpandvalvealignment thatwouldprovidethesmallestNPSHmargin,pumpNPSHrequirements, justificationofthesumpwatertemperature, suctionlinehydraulic losses,andresultant Attachment toAEP:NRC:1280A Page4NPSHmargininaccordance withregulatory guide1.1.Aspartoftheresponsetothisquestion, acopyoftheNPSHcalculation wasincludedasanattachment.

Areviewofthatattachment indicates thattheNPSHwascalculated basedonthefollowing.

Watertemperature, 1904F.Containment

pressure, oneatmosphere (absolute)

Pumpsoperating atmaximumflowrateasdetermined bysystemresistance calculations assumingreactorcoolantsystempressureequalto0psigandallaffectedvalvesconsidered wideopen.ThesinglefailurethatwillresultinthelowestNPSHmarginisthefailureofoneRHRpumptooperate.Inthisinstance, theremaining RHRpumpwilloperateatarunoutcondition.

Noreactorcoolantwaternoricebedmeltdownisusedtoestablish activecontainment sumpwaterinventory.

TheNPSHAcalculations utilizeonlythatportionoftherefueling waterstoragetank(RWST)inventory thathasbeenpumpedintothecontainment priortotheswitchover ofthefirstECCStrainswitch-over fromRWSTtotheactivecontainment sump.RHRpumpdischarge crosstievalves,IMO-314andIM0-324,areopenallowingRHRflowfromonepumptoflowthroughbothRHRheatexchangers.

Containment recirculation sumpdesignincludescoarsegratingatthesumpentranceandfinegrating,perforated plate,inthesumpbackchamberjustupstxeamofthesumpoutletpipes.ThecurrentdesignbasisNPSHcalculation isbasedonthefollowing.\2.3'.'atertemperature, 1904F.Containment

pressure, one,atmosphere (absolute)..

IPumpsoperating asdetermined bysystemresistance calculations assumingreactorcoolantsystempressureequalto0psig,andECCSSIandCCvalvessetasrequiredbytechnical specifications.

ThesinglefailureappliedisthefailureofoneRHRpumptooperate.Inthisinstance, theremaining RHRpumpwillsupplytwoSIpumpsandtwoCCpumpsthroughasingleRHRheatexchanger (see6below).Reactorcoolantwaterandicebedmeltdownisusedtoestablish activecontainment sumpwaterinventory.

Thischangewasdetermined tobeanunreviewed safetyquestion.

Alicenseamendment hasbeenissuedinresponsetooursubmittal AEP:NRC:0900K, datedOctober8,1997.RHRpumpdischarge crosstievalvesareclosedasrequiredbyourprocedure OHP4023.ES-1.3, "Transfer toColdLegRecirculation".

TheRHRpumpdischarge crosstievalvesarenormallyclosedtoprecludedead-heading ofaweakerRHRpump.

Attachment toAEP:NRC:1280A Page5Containment recirculation sumpdesignasmodifiedtoincorporate recommendations fromsumpmodeltestingbyAldenResearchLaboratory.

Modifiedsumpdesignincludestwolayersofgratingthatsandwichasinglelayeroffinemeshscreen,atthesumpentrance.

Finegratingandperforated plateinthesumpbackchamberwereremoved.Therefore, thecurrentdesignbasisNPSHanalysisdiffersfromthemostrecentanalysissubmitted totheNRCasindicated bythedifferences betweenitems3,4,5,6,and7above.GL97-04REVESTNO.4"Specifywhethercontainment overpressure (i.e.,containment pressureabovethevaporpressureofthesumporsuppression poolfluid)wascreditedinthecalculation ofavailable NPSH.Specifytheamountofoverpressure neededandtheminimumoverpressure available."

OURRESPONSETOREVESTNO.4Creditwasnottakenforthecontainment pressureindetermining theNPSHavailable totheECCSpumps.Thecontainment pressureusedindetermining theNPSHavailable isoneatmosphere, absolute.

Nooverpressure orminimumoverpressure wasusedindetermining theavailable NPSH.GL97-04REUESTNO.5"Whencontainment overpressure iscreditedinthecalculation ofavailable NPSH,confirmthatanappropriate containment pressureanalysiswasdonetoestablish theminimumcontainment pressure."

OURRESPONSETOREVESTNO.5Creditisnottakenforcontainment overpressure pressureindetermining theNPSHavailable totheECCSpumps.Thecontainment pressureusedindetermining theNPSHavailable isoneatmosphere.

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