ML17223B040

Submits Comments on Draft Safety Evaluation on Station Blackout Rule (10CFR50.63),per NRC 901121 Request

ML17223B040
Person / Time
Site:	Saint Lucie
Issue date:	12/21/1990
From:	SAGER D A FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-90-452, NUDOCS 9101030143
Download: ML17223B040 (19)

Text

ACCELERATEDDTRIBUTIONDEMONSTRATIONSYSTEMREGULATORYINFORMATIONDISTRXBUTIONSYSTEM(RIDS)ACCESSIONNBR:9101030143DOC.DATE:90/12/21NOTARIZED:NOFACIL:50-335St.LuciePlant,Unit1,FloridaPower&LightCo.50-389St.LuciePlant,Unit,2,FloridaPower&LightCo.AUTH.NAMEAUTHORAFFILIATIONSAGER,D.A.FloridaPower&LightCo.RECXP.NAMERECIPIENTAFFILIATXONDocumentControlBranch(DocumentControlDesk)DOCKET0500033505000389

SUBJECT:

Submitscommentsondraftsafetyevaluationonstationblackoutrule(10CFR50.63),perNRC901121request.DISTRIBUTIONCODE:A050DCOPIESRECEIVED:LTRENCL0SIZE:(0TITLE:ORSubmittal:StationBlackout(USIA-4410CFR5.63,MPAA-22NOTES:RECIPIENTIDCODE/NAMEPD2-2PDXNTERNAL':ACRSNRR/DET/ESGB8DNRR/J39g+SPLB8D1~KEGFILE01EXTERNAL:NRCPDRCOPIESLTTRENCL1111223311RECIPIENT.XDCODE/NAMENORRIS,JNRRPD1-4PMTAMNRR/DST/SELBNRR/DST/SRXB8ENSICCOPIESLTTRENCL1111331111NOTETOALL"RIDS"RECIPIENTS:PLEASEHELPUSTOREDUCEiVASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMP1-37(EXT.20079)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLISTSFORDOCUMENTSYOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED:LTTR16ENCL16 P.O.Box128,Ft.Pierce,FL34954-0128December21,1990L-90-45210CFR50.63U.S.NuclearRegulatoryCommissionAttn:DocumentControlDeskWashington,D.C.20555Gentlemen:Re:St.LucieUnits1and2DocketNos.50-335and50-389StationBlackoutRule-10CFR50.63ByletterdatedNovember21,1990(J.A.NorristoJ.H.Goldberg),theNRCforwardedtoFloridaPower&LightCompany(FPL),forcomment,adraftSafetyEvaluationontheStationBlackout(SBO)rule(10CFR50.63)forSt.LucieUnit1.FPLstronglydesirestoresolveSBOforSt.LucieUnits1and2inthesamemannernotwithstandingtheexemptionfromtherulerequirementsgrantedforSt.LucieUnit2.Inthislight,FPLprovidesthefollowingcomments.FPL'sapproachtotransientandemergencyeventsatitsnuclearpowerplantsensuresthecontinuedavailabilityofAlternatingCurrent(AC)electricalpower.Thisapproachhasbeenanintegralpartofournuclearplantoperatingstrategy.TheSBOrulepermitslicenseestoimplementthisstrategyinmeetingthecriteriaandrequirementsof10CFR50.63.FPLiscommittedtoresolveSBOforSt.LucieUnits1and2byuseofanalternateAC(AAC)source.FPLproposestomeettherequirementsoftheSBOrulebypreventingaunitblackoutorSBO;inthatrespect,theSt.LucieunitswillnotcopewitheithereventusingDirectCurrent(DC)power,but,ratherwillrecoverfromaLossofOffsitePower(LOOP)withtheassumedmultipleEDGfailuresbymeansofaunittounitACelectricalcrosstie.Thesafetyandnon-safetyrelatedequipmentFPLhasproposedtoloadonthesingleoperatingEmergencyDieselGenerator(EDG)isequipmentwhichisnecessarytoplacebothunitsinsafeshutdown(i.e.,hotstandby).FPL'scommentspresentedintheattachmenttothisletteraddressthefollowingaspectsoftheNRC'sdraftSafetyEvaluation:1)TheresolutionofSBOforSt.LucieUnits1and2usingtheAACsourceapproachincreasessafetymarginsfromthatofaDirectCurrent(DC)copingapproach.2)ElectricalloadingoftheoperatingEDGforthisevent(9i0103014390i22iPDRADOCK05000335PPDRA$~.nonFPLGroupcompany

tg,44ll~l1 includestheACloadsnecessarytocopewithaLOOPandfailureofthreeEDGsforbothunits,excludingthefollowingloads,asallowedbycriteriaembodiedin10CFR50.63:a)ShutdownCooling(SDC)pumpsb)ACdrivenAuxiliaryFeedwater(AFW)pumps3)ReactorcoolantdepletionviasealleakageattherateassumedintheNRC'sSafetyEvaluationisnotaconsiderationforeitherunit.4)Managementofthesiteoperationsdictatesstandardizedprocedures,training,TechnicalSpecifications,andlicensinganddesignbasesforbothunitsonthesite.SincetheSt.LucieplantoperatorsarelicensedtooperatebothSt.Lucieunits,'ifferentlicensingbases,TechnicalSpecifications,andemergencyoperatingproceduresforrecoveringfromSBOoneitherunitwillpresentunnecessaryhumanfactorsconcerns.Attachedareourdetailedcommentsontheaboveissuesaswellasotheraspectsofthestaff'sdraftSafetyEvaluation.WeappreciatetheopportunitytoreviewandcommentonthisSafetyEvaluation.Verytrulyyours,D.A.aViceeridentSt.LuciePlantDAS/EJW/lefDAS/PSL75312cc:StewartD.Ebneter,RegionalAdministrator,USNRC,RegionIISeniorResidentInspector,USNRC,St.LuciePlant J~'It,1+%A,ph~Q~'

ATTACHMENTFPLcommentsonNRCdraftSafetyEvaluationStationBlackoutRuleSt.LucieUnits1and2.FPLstronglydesirestoresolve10CFR50.63forbothSt.LucieUnits1and2inthesamemanner(i.e.,bymeansofanalternateAC(AAC)source).FPLhasidentifiedseverallicensinganddesignconcernswiththeresolutionof10CFR50.63inthestaff'sdraftSafetyEvaluation(SE),asdetailedbelow.IntroductionFPL'scompliancewith10CFR50.63,"Lossofallalternatingcurrentpower",andtheguidanceprovidedbyRegulatoryGuide1.155andNUMARC87-00areaimedatmeeting10~perreactoryearasanacceptablefrequencyforcoredamagecontributionfromsequencesinitiatedbyastationlossofoffsitepower(LOOP)'sestablishedbytheNRC.ResolutionofStationBlackout(SBO)forSt.LucieUnits1and2consistsofplantenhancementsandmodificationswhichwillresultinreducedfrequencyofcoredamagefromaunitorstationblackouteventtolessthan105perreactoryear.TheAdvisoryCommitteeonReactorSafeguards(ACRS),CommitteetoReviewGenericRequirements(CRGR)andNRCstaffrecognizedthatsomelicenseescouldprovide,ormayactuallyhaveinplace,additionaldiesels,gasturbinesorcross-connectoptionsattwo-unitsitesthatcouldserveasaone-of-fouremergencydieselgenerator(EDG)configurationratherthanone-of-twoEDGconfigurationsforunitblackoutconsiderations'.Thisrecognitionledtothe"10-minute"alternateAC(AAC)sourceatmulti-unitsites.Infact,thestatementsofconsiderationfortheruleidentifiedthisapproachasa"preferredoption"toresolve10CFR50.63.InlettersdatedApril17,1989andMarch7,1990(L-89-145andL-90-58,respectively),FPLproposedtoaddaremotemanualelectricalintertietocross-connectelectricalbusesbetweenSt.LucieUnits1and2suchthatthereliabilityoftheemergencyACpowersystemconfigurationafteraLOOPissignificantlyimproved.ThisconfigurationpermitsanyoneoffourEDGstomitigatetheeffectsofaunitblackoutatthe'NRCstaffresponsestoquestionsfromCommissionersAsselstine,Bernthal,RobertsandZechduringfinalrulemakingdecisionon"StationBlackout"regulationdateNovember10,1985.

site.FPLhasshownthatoneEDGissufficienttoprovideallthenecessaryloadsassociatedwithplacingbothunitsinhotstandbyfrom1004powerfortherequiredblackoutduration.Additionally,FPLhasperformedapreliminaryriskassessmentwhichreflectsthesignificantriskreductiongainedbythemodificationsforapostulatedSBOevent.2)IncreasedSafetyMarginsforAACApproach.FPL'spreliminaryevaluationofriskreductionasaresultoftheAACapproachdemonstratesthatthecoremeltriskfromSBOafteraLOOPeventhasbeenreducedfromapproximately7.6x104to2.9x10~perreactoryear.Thisisdirectlyattributabletotheproposedunit-to-unitcross-tiecapabilityoftheelectricalsystemresultingintheaddedavailabilityoftwoEDGs.Theevaluationresultsinariskreductionfactorinexcessof200.Bycomparison,inNUREG-1032,"EvaluationofStationBlackoutAccidentsofNuclearPowerPlants"andinNUREG-1109,"RegulatoryAnalysisfortheResolutionofUnresolvedSafetyIssueA-44,StationBlackout",theNRCstaffreportsariskreductionfactorofapproximately2.5(i.e.2.1x10to0.8x10~perreactoryear)asthebasisforissuanceoftheSBOruleforunitswitha4hourDCcopingcapabilityandone-out-of-twoEDGconfiguration~.3)AlternateAC(AAC)LoadingFPLhasre-analyzedtheemergencydieselgenerator(EDG)loadingfortheproposedbusintertieforSt.LucieUnits1and2tomeetSBOcriteria.Thisre-analysisresultsinrevisedloadprofilesfromthoseprovidedtotheNRCstaffduringtheOctober1989SBOaudit.TheproposedelectricalloadingsfortheEDGstoaccommodatetheSBOeventareprovidedinattachedTable1forSt.LucieUnit1andTable2forSt.LucieUnit2.TheseloadingsareessentiallythemajorLOOPloadslistedintheUpdatedFinalSafetyAnalysisReport(UFSAR)withthefollowingexceptionstoaccountfortherequirementsof10CFR50.63:a)TheSBOandnon-blackedout(NBO)units'oadingsdonotincludethemotordrivenAuxiliaryFeedwater(AFW)pumps.TheNBOunitassumesfailureofaredundantEDG(i.e.,failureofthreeEDGsafterLOOPeventatthesite)toqualifythefourthEDGasanAACsource.AnassumedfailureoftheturbinedrivenAFWpumponeithertheSBORulemakingIssueAffirmation,SECY-88-22,January21,1988.

~~Pegg$vk,t orNBOunitforthiseventgoesbeyondtheassumptionsrequiredbytheregulations;FPLbelievesthatthisassumptionisnewcriterionwhichwasnotconsideredintheregulatoryanalysisfor10CFR50.63norisitincludedinRegulatoryGuide1.155.Theregulatoryanalysisfor10CFR50.63isbasedonasafetygoallimitingtheaveragecontributiontocoredamagefromaSBOtoabout10'erreactoryear.Asacomparison,theNRCstaff,inNUREG/CR-4710,"ShutdownDecayHeatRemovalAnalysisofa.CombustionEngineering2-LOOPPWR"hasanalyzedanumberoffailureprobabilitiesfortheSt.LuciePlant.TheNUREGreportsthatfailureofaturbinedrivenAFWpumpcoupledwithacommonmodefailureof2EDGsafteraLOOPeventresultsinafrequencyofoccurrenceof8.2x10~perreactoryear.ForthepostulatedSBOeventanadditionalEDGfailuremustbeassumed.Thisadditionalfailurewillfurtherreducethecoredamagecontributionbyafactorof5x10~.FPLbelievesthatthisisinconsistentwiththeanalysesusedtosupport10CFR50.63andistherefore,anewregulatorycriterionbeyond10CFR50.63.TheNRC-approvedguidelinesfrom"CombustionEngineeringEmergencyProceduresGuidelines"CEN-152,Rev.03,addressoperatoractionsforLOOPandSBOevents.TheseguidelinesandFPL'sproceduresgeneratedusingtheseguidelinescallforlimitingflowtoanyonesteamgeneratorduringtheseeventsto150gpmtominimizetheprobabilityofotherpostulatedover-coolingevents.TheturbinedrivenAFWpumphasgreatercapacitythanthemotordrivenpumpsandiscapableofsupplyingsufficientAFWflowtobothsteamgeneratorsfordecayheatremoval.FPL'semergencyoperatingprocedures,whichweredevelopedusingtheguidanceofCEN-152,requiretheoperatorstorestrictAFWflowbyplacingthemotordrivenpumpintherecirculationmodeforthepostulatedcasewhereaLOOPeventhasoccurredandthreeofthefourEDGsdonotstart.Procedureswillinstructtheoperatorto:i)verifyflowfromtheturbinedrivenAFWpump,ii)secureflowfromtheNBOunit'smotordrivenpump(inaccordancewithCEN-152guidance),andiii)proceedwiththe10-minutebusintertietopowertheblackedoutunit.SimilaractionswilltakeplaceontheSBOunit.Basedontheabove,theSBOloadevaluationdoesnotrequireincludingthemotordrivenAFWpump.

• /Q'al b)Title10CFR50.63andNUMARC87-00definesafeshutdownashotstandbyorhotshutdown,asappropriate.ForEDGevaluationpurposes,FPLintendstomaintainbothunitsathotstandbyfortheeighthourLOOP/SBOduration.Forunitsinhotstandby,operatingpressuresandtemperaturesprohibittheuseandoperationoftheShutdownCooling(SDC)system(i.e.,theLowPressureSafetyInjectionpumpswhichareusedinnon-accidentconditionsforshutdowndecayheatremoval).PursuanttothedesignbasesoftheSt.LucieUnits1and2,theSDCsystemismanuallyplacedintoservicewhentheReactorCoolantSystem(RCS)pressureisapproximately275psig,andtemperatureislessthan325degreesF.TheSt.LucieUnits1and2SBOEDGloadingevaluationswillnotconsidermodechanges(i.e.,tocoldshutdown)duringtheeighthourAACcopingperiod;therefore,theSDCsystemwillnotbeusedduringthistime.Basedontheabove,FPLhasnotincludedtheSDCpumploadsintheEDGloadevaluationforSBO.4)ReactorCoolantInventorySt.LucieUnits1and2useAACforsafeshutdownduringthepostulatedSBOevent.FPLbelievesthegenericReactorCoolantPump(RCP)leakagecriterionof25gpmperpump(forplantswithDCcoping),wasintendedtoaddressunitsthatdonotprovidecoolingtotheRCPseals.AsAACplants,St.LucieUnits1and2willprovidecoolingwatertotheRCPsealsontheSBOunitshortlyafterenergizingtheintertie(i.e.,inapproximately10minutes).Asaresult,nosealdamageispostulatedandonlynormalsealleakoffneedbeassumedfortheRCPs.WithrespecttotheintegrityofSt.LucieUnit.1and2RCPsealsfollowingalossofcomponentcooling,itshouldbenotedthattheintegrityoftheRCPsealsofthetypeusedintheSt.LucieUnit1and2reactorcoolantpumpswasverifiedinaqualificationtestconductedatthepumpmanufacturer'stestfacility.Thisfull-scaletestsimulatedalltheconditionsoftemperature,pressureandfluidflowthatwouldbeexperiencedinaLOOPeventwhensealcoolingisinterruptedandthepump,shaftstopped.ItwasthegoalofthetesttoidentifytheeffectsoflossofcoolingtothesealsoverafourhourperiodwhichwouldrepresentanextendedlossofACpower.Afterfourhourswithoutanycoolingwaterflow,therewasnoobservedincreaseinsealleakagealthoughthesealtemperatureshadrisentoover400'Fwhilethesystempressurewasmaintainedat2500psi.Thetestwascontinuedforover50hoursandatnotimedidseal Y.1if%

leakageexceed16.1gallonsperhour.ThistestdemonstratedthattheRCPsealswillmaintaintheirintegritythroughanextendedLOOPevent.ThistestwasperformedtoprovideinformationtoresolvetheSt.LucieUnit2lossofACpowerOperatingLicensingreviewandtheinformationisdirectlyapplicabletoSt.LucieUnit1whichutilizesidenticalRCPseals.ThetestreaffirmedthattheRCPsealsusedinSt.LucieUnit1and2willwithstandtheenvironmentassociatedwithasustainedlossofACpowerandwillnotdegradethereactorcoolantpressureboundary.5)OtherCommentsa)StationBlackoutDuration(Section2.1)Withrespecttothecopingassessment,St.LucieUnits1and2shouldbeevaluatedasAACplantswithpoweravailabletotheshutdownbuseswithin10minutesoftheonsetofanSBOevent.Therefore,acopingassessmentdoesnotneedtobeaddressed.b)AlternateACAACSource(Section2.2)ThestrategyforrecoveringfromanSBOeventonbothSt.Lucieunitswillinvolveelectricloadmanagement(i.e.,manualactionsoutsidetheControlRoom).Trainedoperatorsareanimportantandnecessarypartoftheplant's.responsetoanyLOOPandconcurrentunitblackoutrecoveryplan.FPLmaintainsthatoperatorscanandwillperformloadmanagementactionsrequiredtomaintainthenecessaryloadsforsafeshutdownwhileensuringtheEDGremainswithinitsloadrating.InaccordancewiththeSBOrule,atestwillbeperformedtoverifythattheAACpowersourcewillbeavailabletopowertheshutdownbuseswithin10minutesoftheonsetofSBO.c)ComressedAir(Section2.3.3)TheaircompressorshavethecapabilitytobemanuallyloadedontheEDGs.Theseaircompressorsareelectricallydriven,notdieseldriven.Inaddition,thecompressorswilloperateasrequired(notcontinuously)tomaintainpressure.Thisequipmentisnotrequiredtomaintainhotstandbybuthasbeenaddedasanoperatora3.d~

r'Jt d)EffectsofLossofVentilation(Section2.3.4)AllnecessaryventilationequipmentwillbepoweredbytheAACSourceduringanSBOevent.Therefore,additionalventilationstudiesarenotrequired.e)ScoeofStaffReview(Section2.8)AsdiscussedinthecommentsonSection2.3.4,"EffectsofLossofVentilation",itemf(heatingandventilationcalculations)shouldbedeleted.f)St.LucieUnit2SBOWithstandCaabilit(Section3.0)Asdiscussedabove,theEDGsofeitherUnit1orUnit2arecapableofsupplyingtheSBOloadsofbothunits.Therefore,theEDGsfrombothUnit1and2havethecapabilityandcapacitytobeAACpowersources.g)SummarandConclusions(Section4.0)Basedoncommentsfortheprecedingsections,thissectionshouldberevisedaccordingly.

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~~4FloridaPowerandLightTable1St.LucieUnit1ElectricalLoadingsUNIT1DESIGNATIONSPDHDSH~FLAHP/KVAKWEMERGENCYLIGHTINGCLASS1EPOWERPANELSCONTAINHENTFAHCOOLERS(2)COHPOHENTCOOLIHGWATERPUHPSINTAKECOOLINGWATERPUHPSICWBUILDINGCOOLINGFANSCONTROLROOMA/CAUXILIARYBUILDINGSUPPLYFANSECCSAREAEXHAUSTFANSREACTORCAVITYCOOLINGFANSREACTORSUPPORTCOOLINGFANSEEROOMSUPPLYFANSEEROOMEXHAUSTFANSEEROOMROOFVENTSBATTERYROOHEXHAUSTFANSBATTERYCHARGERSUPSINVERTERSPLANTSECURITYINVERTERSPRESSURIZERHTRS.BACKUPBANKINST'IR(IA)COMPRESSORSCOOLINGFORIACOMPRESSORSEDGFUELTRANSFERPUMPSCHARGINGPUHPSMISC.LP'SMISC.PP'S1HVS1A&BORC&01A,18,1C1A,18,1CACC&HVA3A,B,C1HVS4A,481HVE9A,981HVS2A,281HVE3A,381HVS5A,581HVE11,121RV3,1RV41RV1,1RV21A,18INV.UPS.REC.PL.SEC.INV.*82OR85*1A,18AIRCOMPMOTOR*1A,18*1A,18,1C164,54,535,36,4134,3936,4231,3831,3933,3935,4132,415C,5332,394444A1935,43A626216203608154.4/10.67259,49264938102.54.29047.248.6387.5049112111815045060040/7.56050,40204022.17.51.5.2568KVA20KVA20KVA186407.55100125.75149.08123.00369.00451.0042.7044'037.8315.4621.5713.484.391.400.2268.0020.0020F00186.0036.006.704.5082F0086.85109.14123.00369.00451~0042.7044.2032.2015.4621.5713.484.391.400.2268.0020.0020.00186.0036.006.704.5082.00*USEDINTERHITTENTLY-ONLYPRESSURIZERHEATERSINCLUDEDINTOTAL1693.081608.61UNIT1EDGRATINGSREF.FLO8770-305CONTINUOUSDUTY-"3500KW2000HRSRATING=3730KW7DAYRATING=3790KW4HRSRATING=3860KW30HINRATING-"3960KWU1MAXIMUMVALUE=1693.08KWU2MAXIHUHVALUE=1800.11KWCOMBINEDTOTAL=3C93.19KWCOMBINEDTOTAL=100KOFUNIT1,CONT.RATING SWI

-FloridaPowerandLightTable2St.LucieUnit2ElectricalLoadingsUNIT2DESIGNATIONSPDMDSH.FLAHP/KVAKWEMERGENCYLIGHTINGCLASS1EPOWERPAHELSCONTAINMENTFANCOOLERS(2)COMPONENTCOOLINGWATERPUMPSINTAKECOOLINGWATERPUMPSICWBUILDINGCOOLINGFANSCONTROLROOMA/CAUXILIARYBUILDINGSUPPLYFANSECCSAREAEXHAUSTFANSREACTORCAVITYCOOLINGFANSREACTORSUPPORTCOOLINGFANSEEROOMSUPPLYFANSEEROOMEXHAUSTFANSEEROOMROOFVENTSBATTERYROOMEXHAUSTFANSBATTERYCHARGERSUPSINVERTERSPLANTSECURITYINVERTERSPRESSURIZERHTRS~PROPSBANKSINST.AIR(IA)COMPRESSORSCOOLINGFORIACOMPRESSORSEDGFUELTRANSFERPUMPSCHARGINGPUMPSMISC.LP'SMISC.PP'S2HVS1A&BORC&D2A,2B,2C2A,28,2C2HVE41A,B2HVA/ACC-3A,B,C2HVS-4A,4B2HVE9A,982HVS2A,2B2HVE'3A,3B2HVS5A,5B2HVE11,122RV3,2RV42RV1,2RV22A,28INV.UPS.REC.VITALA/CCAB.*P1ORP2*2A,28"AIRCOMPMOTOR*2A,2B*2A,28,2C1024,54,534,3936,4211131,423736,3933,3935,4132,4137A,43832,394444A1935,436262161446082.49.468.1,4916573,652447115596.591.429018,4060312.5751141451254506007.555,4015060'20401005050.7568KVA20KVA30KVA150KW607.5312584.9265.84141.00369.00492.006.7049.40112.9750.8113.6621.7777.1741.744.460.6768.0020F0030.00150.0054.006.802.70102.4769.4354.87141.00369.00492.006.7049.40112.9752.9413.6621.7777.1741.744.460.6768.0020.0030F00150.0054.006.802.70102.47*USEDINTERMITTENTLY-ONLYPRESSURIZERHEATERSINCLUDEDIHTOTAL1800.111775.78UNIT2EDGRATINGSREF.FLO2998-305CONTINUOUSDUl'Y=3685KW2000HRSRATING"-3935KW7DAYRATING=3985KW4HRSRATING<3985KW30MIHRATING-"3985KWU1MAXIMUMVALUE~1693~08KWU2MAXIMUMVALUE=1800~11KWCOMBINEDTOTAL<3493.19KWCOMBINEDTOTAL>95XOFUNIT2,CONT.RATING