ML18026A537
ML18026A537 | |
Person / Time | |
---|---|
Site: | Susquehanna |
Issue date: | 02/21/1995 |
From: | BYRAM R G PENNSYLVANIA POWER & LIGHT CO. |
To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
References | |
PLA-4273, NUDOCS 9502270258 | |
Download: ML18026A537 (56) | |
Text
PR.I(3RIEY1(ACCELERATED RIDSPROCESSIXREGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9502270258 DOC.DATE:
95/02/21NOTARIZED:
NOFACIL:50-387 Susquehanna SteamElectricStation,Unit1,Pennsylva 50-388Susquehanna SteamElectricStation,Unit2,Pennsylva AUTH.NAMEAUTHORAFFILIATION BYRAM,R.G.
Pennsylvania Power&LightCo.RECIP.NAME RECIPIENT AFFILIATION DocumentControlBranch(Document ControlDesk)
SUBJECT:
ForwardsFSARchangedelineating useofRHRfuelpoolcoolingmodeofoperation tomitigatelossofnormalspentfuelpoolcoolingsysinresponsetoseismicevent,per commitment madevia941228ltr.DISTRIBUTION CODE:AOOIDCOPIESRECEIVED:LTR lENCL3SIZE:5TITLE:ORSubmittal:
GeneralDistribution NOTES:DOCKETN050003870500038805000387RECIPIENT IDCODE/NAME PDl-2LAPOSLUSNY,C INTERNAL:
ACRSNRR/DRCH/HICB NRR/DSSA/SRXB OGC/HDS2EXTERNAL:
NOACNOTES:COPIESLTTRENCL11116611111011RECIPIENT IDCODE/NAME PD1-2PD/D/NUDOCS-ABSTRACT NRCPDRCOPIESLTTRENCL1111111111NOTETOALL"RIDS"RECIPIENTS:
PLEASEHELPUSTOREDUCEO'ASTE!CONTACTTIIE DOCL'ifENTCONTROL DESk,ROOAIPI-37(EXT.504-0033)TOELIXIINiATEYOURNAiILFROifDISTRIBUTION LISTSI'ORDOCI.'4IEN'I'SYOL'ON"I'L'I'.D!
TOTALNUMBEROFCOPIESREQUIRED:
LTTR18ENCL17
~0Pennsylvania Power8LightCompanyTwoNorthNinthStreet~Allentown, PA18101-1179
~610/774-5151 FEB211995RobertG.ByramSeniorVicePresident
-Nuclear610/774-7502 Fax:610/774-5019 U.S.NuclearRegulatory Commission Attn.:DocumentContr'olDeskMailStationP1-137Washington, D.C.20555SUSQUEHANNA STEAMELECTRICSTATIONFSARCHANGE:RHRFUELPOOLCOOLINGDocketNos.50-387and50-388
Reference:
PLA-4230, RG.ByramtoUShfRC,"LossofSpentFuelPoolCoolingfromSeismicEvent/Use ofRHRFuelPoolCoolingMode",datedDecember28,1994.
DearSir:
Viathereferenced letter,PP&Lcommitted toprovideanFSARchangedelineating theuseoftheRHRFuelPoolCoolingmodeofoperation tomitigatethelossofnormalspentfuelpoolcoolingsysteminresponsetoaseismicevent.AcopyoftheFSARchangeisattachedforyouruseandinformation.
Althoughthischangehasbeenreviewedandapprovedinternally, PP&Listreatingthischangeaspreliminary pendingissuanceofthefinalNRCSafetyEvaluation onSpentFuelPoolCoolingissues.Uponissuanceofthatdocument, wewillresolveanydiscrepancies andformallyissuetheFSARchangeperournormalprocedures.
Ifyouhaveanyquestions ontheattachment, pleasecontactMr.J.M.Kennyat(610)774-7904.
Verytrulyyours,iR.G.yraAttachment CC:NRCRegionIMs.M.Banerjee, NRCSr.ResidentInspector
-SSESMr.C.Poslusny, Jr.,NRCSr.ProjectManager-OWFNMr.J.Shea,NRCProjectManager-OWFNIDR950227ADOCK05000>8PDP NOTE:Pagenumbersinparenthesis (Iindicateaspill-over frompreviouspages.TheydonotcoincidewiththetextonthatpageintheFSAR....9502270258 SSES-FSAR averagelifeexpectancy manytimestheresidence timeofafuelloading.1.2.2.3.2 ReactorVesselandInternals Thereactorvesselcontainsthecoreandsupporting structure; thesteamseparators anddryers;thejetpumps;thecontrolrod,guidetubes;distribution linesforthefeedwater, corespray,andstandbyliquidcontrol;theincoreinstrumentation; andothercomponents.
Themainconnections tothevesselincludethesteamlines,thecoolantrecirculation lines,thefeedwater lines,thecontrolroddrivehousings, andtheECCSlines.Thereactorvesselisdesignedandfabricated inaccordance withapplicable codesforapressureof1250psig.Thenominaloperating pressureis1020psiainthesteamspaceabovetheseparators.
Thevesselisfabricated ofcarbonsteelandiscladinternally withstainless steel(exceptforthetopheadwhichisnotclad).Thereactorcoreiscooledbydemineralized waterthatentersthelowerportionofthecoreandboilsasitflowsupwardaroundthefuelrods.Thesteamleavingthecoreisdriedbysteamseparators anddryers,locatedintheupperportionofthereactorvessel.Thesteamisthendirectedtotheturbinethroughfourmainsteamlines.
Eachsteamline isprovidedwithtwoisolation valvesinseries,oneoneachsideoftheprimarycontainment barrier.1.2.2.3.3 ReactorRecirculation SstemTheReactorRecirculation Systempumpsreactorcoolantthroughthecoretoremovetheenergygenerated inthefuel.Thisisaccomplished bytworecirculation loopsexternaltothereactorvesselbutinsidetheprimarycontainment.
Eachloophasonemotor-driven recirculation pump.Recirculation pumpspeedcanbevariedtoallowsomecontrolofreactorpowerlevelthroughtheeffectsofcoolantflowrateonmoderator voidcontent.1.2.2.3.4 ResidualHeatRemovalSstemTheResidualHeatRemovalSystem(RHRS)consistsofpumps,heatexchangers andpipingthatfulfillthefollowingfunctions:
a~b.Removalofdecayheatduringandafterplantshutdown.
Rapidinjection ofwaterintothereactorvesselfollowing alossofcoolantaccident, ataratesufficient torefloodthecoremaintainfuelcladdingbelowthelimitscontained in10CFR50.46.Thisisdiscussed inSubsection 1.2.2.4.Rev.47,06/941.2-14 SSES-FSAR c~Removalofheatfromtheprimarycontainment following aloss-of-coolant accident(LOCA)tolimittheincreaseinprimarycontainment pressure.
Thisisaccomplished bycoolingandrecirculating thewaterinsidetheprimarycontainment.
Theredundancy oftheequipment providedforthecontainment isfurtherextendedbyaseparatepartoftheRHRSwhichsprayscoolingwaterintothedrywell.,Thislattercapability isdiscussed inSubsection 1.2.2.4.12.
d.Provideforcoolingofthespentfuelpool(s)following aseismiceventwhichresultsinalossofnormalspentfuelpoolcooling,inconjunction withnormalshutdownofbothunits.1.2.2.3.5 ReactorWaterCleanuSstemRWCUAReactorWaterCleanupSystem,whichincludesafilterdemineralizer, isprovidedtocleanupthereactorcoolingwater,toreducetheamountsofactivated corrosion productsinthewater,andtoremovereactorcoolantfromthenuclearsystemundercontrolled conditions.
1.2.2.4SafetRelatedSstemsSafetyrelatedsystemsprovideactionsnecessary toassuresafeshutdown, toprotecttheintegrity ofradioactive materialbarriers, and/ortopreventthereleaseofradioactive materialinexcessallowable doselimits.Thesesystemsmaybecomponents, groupsofcomponents, systems,orgroupsofsystems.Engineered SafetyFeature(ESF)systemsareincludedinthiscategory.
ESFsystemshaveasolefunctionofmitigating theconsequences ofdesignbasisaccidents.
1.2.2.4.1 ReactorProtection SstemTheReactorProtection Systeminitiates arapid,automatic shutdown(scram)ofthereactor.Thisactionistakenintimetopreventexcessive fuelcladdingtemperatures andanynuclearsystemprocessbarrierdamagefollowing abnormaloperational transients.
TheReactorProtection Systemoverrides alloperatoractionsandprocesscontrols.
Rev.46,06/931.2-15 SSES-FSAR 1.2.2.4.2 Neutron-Monitorin SstemNotalloftheNeutronMonitoring Systemqualifies asanuclearsafetysystem;onlythoseportionsthatprovidehighneutronfluxsignalstotheReactorProtection Systemaresafetyrelated.Theintermediate rangemonitors(XRM)andaveragepowerrangemonitors(APRM),whichmonitorneutronfluxviain-coredetectors, signaltheReactorProtection Systemtoscramintimetopreventexcessive fuelcladtemperatures asaresultofabnormaloperational transients.
Rev.46,06/931.2-(16)
SSES-FSAR 3.1.2.1.5 SharingofStructures, Systems,andComponents Criterion 5Criterion Structures, systems,andcomponents important tosafetyshallnotbesharedamongnuclearpowerunitsunlessitcanbeshownthatsuchsharingwillnotsignificantly impairtheirabilitytoperformtheirsafetyfunctions, including, intheeventofanaccidentinoneunit,anorderlyshutdownandcooldownoftheremaining units.DesinConformance AlthoughSusquehanna SESUnits1and2sharecertainstructures, systems,andcomponents, sharingthemdoesnotsignificantly impairperformance oftheirsafetyfunctions.
Thefollowing safetyrelatedstructures aresharedbetweenbothunits:ControlStructure DieselGenerator Buildings ESSWPumphouse SprayPondSpentFuelPoolsThesafetyrelatedstructures aredesignedtoremainfunctional duringand,following themostseverenaturalphenomena.
Therefore sharingthesestructures willnotimpairtheirabilitytoperformtheirsafetyfunctions.
SeismicCategoryI'tructures whichhousesafetyrelatedsystemsandequipment arediscussed inSection3.8.Thesharedsystemswhichareimportant.
tosafetyarediscussed below;amoredetaileddiscussion
-maybefoundinthereferenced Subsections:
a)b)c)d)e)f)Emergency ServiceWaterSystemDieselGenerators UltimateHeatSink'(SprayPond)OffsitePowerSuppliesUnit1ACDistribution SystemResidualHeatRemoval(FuelPoolCoolingMode)(ESWS)9.2.58.3.1.49.2.5SE9.2.68.28.3.15.4.7.1.1
'Rev.47,06/943.1-6
,~1SSES-FSAR EmerencServiceWaterSstemESWSTheESWSisdesignedtoa)SupplycoolingwatertotheRHRpumpsandtheirassociated roomcoolersduringtheseveralnon-emergency modesofRHRpumpoperation suchasnormalshutdown, andhotstandby.b)Supplycoolingwatertothevariousdieselgenerator heatexchangers, RHRpumps,roomcoolers,RBCCWandTBCCWheatexchangers duringemergency shutdownconditions suchasaLOCA.c)SupplycoolingwatertotheRHRpumpsandtheirassociated roomcoolersduringaseismiceventthatresultsinalossofthenon-seismic CategoryIFuelPoolCoolingSystem.Duringthisevent,ESWSwouldalsosupplywatertothespentfuelpoolstomake-upforevaporative lossesandfillthespentfuelpoolstotheproperlevelneededtosupporttheRHRFPCmodeshouldthenormalmake-upsourcebeunavailable.
TheESWSpumpsarelocatedintheESWSpumphouse withtheRHRSWpumps.TheESWSpumphouse isdesignedasSeismicCategoryIandtheESWSconsistsoftworedundant loops(denotedAandB)eachcapableofproviding 100percentofthecoolingwaterrequiredbyalltheESFequipment ofbothUnits1and2simultaneously.
Thesystemisdesignedsothatnosingleactiveorpassivecomponent failurewillpreventitfromachieving itssafetyrelatedobjective.
Thesystemstartsautomatically onadieselstartsignal.Foradditional discussion, seeSubsection 9.2.5.DieselGenerators DieselGenerators A,B,CandDarehousedinaSeismicCategoryIstructure.
Theyareseparated fromeachotherbyconcretewallswhichprovidemissileprotection.
Additionally, asparedieselgenerator (DieselGenerator
'E')isprovidedwhichcanbemanuallyrealigned asareplacement foranyoneoftheotherfourdieselgenerators.
Thus,anyoneoftheotherdieselgenerators (A,B,CorD)canberemovedfromserviceforextendedmaintenance andtheDieselGenerator
'E'anbesubstituted sothattherearefouroperabledieselgenerators.
DieselGenerator
'E'shousedinitsownSeismicCategoryIstructure whichalsoprovidesmissileprotection.
Lossofoneofthefouraligneddieselgenerators willnotimpairthecapability tosafelyshutdownbothunits,sincethiscanbeRev.47,06/943017 SSES-FSAR donewiththreedieselgenerators.
Foradditional discussion, seeSubsection 8.3.1.4.Fordescriptions oftheDieselGenerator FuelOilSystem,CoolingWaterSystem,AirStartingSystem,LubeOilSystem,andtheIntakeandExhaustSystemsseeSubsections 9.5.4,9.5.5,9'.6,9.5.7,and9.5.8respectively.
Formissileprotection seeSubsection 3.5.Separation isdiscussed inSections3.12and8.3.UltimateHeatSinkSraPondThespraypondprovidesthewaterforboththeESWSsystemandtheRHRSWsystems.ItistheultimateheatsinkforbothUnits1and2.ThereturnlinesfromtheESWSandtheRHRSWarecombinedandthetotalquantityofwaterfromboththesesystemsisdischarged throughspraynetworks, whichdissipate theheatbacktothepond.Therearetworedundant returnloops(AandB);eitheroneiscapableofhandlingthefullflowfromtheESWSandRHRSWwhenshuttingdowntwounitssimultaneously.
Eachreturnloopsuppliesaseparatespraynetworkandeach,ofthesenetworksisdividedintoalargeonecapableofdissipating theheatfromtheESWSandtheRHRSWfromtheRHRheatexchanger ononeunit,andasmalleronecapableofdissipating theheatfromtheRHRheatexchanger onthesecondunit.Thespraypondcontainssufficient watertomeettherequirements forshuttingdownoneunitintheeventofanaccidentandtopermitthesafeshutdownofthesecondunitforaperiodofthirtydayswithoutmakeup.Foradditional discussion seeSubsections 9.2.5and9.2.6.OffsitePowerSuliesThetwopreferred offsitepowersuppliesaresharedbybothunits.Thecapacityofeachoffsitepowersupplyissufficient tooperatetheengineered safetyfeaturesofoneunitandsafeshutdownloadsoftheotherunit.Foradditional discussion, seeSection8.2.Unit1ACDistribution SstemTheUnit1ACDistribution Systemisasharedsystembetweenbothunits,sincethecommonequipment (Emergency ServiceWater,StandbyGasTreatment System,ControlStructure HVAC,etc.)isenergized onlyfromtheUnit1ACDistribution System.Rev.47,06/943.1-8 SSES-FSAR TherearenoUnit2specificloadsenergized fromtheUnit1ACDistribution System.ThecapacityoftheUnit1ACDistribution Systemissufficient tooperatetheengineered safetyfeaturesononeunitandthesafeshutdownloadsoftheotherunit.ResidualHeatRemovalFuelPoolCoolinMode)WiththeSpentFuelPoolscrosstied, oneunit'sRHRsystemcanbeusedtocoolstoredspentfuelinbothspentfuelpools.Inthecrosstied configuration, theRHRFPCmodeofoneunitwilldrawsuctionfromthatunit'sskimmersurgetankandreturnthecooledflowtothebottomoftheunit'sfuelpool.Nodirectflowtoorfromtheoppositeunit'sfuelpoolwillbeaccomplished.
Withthepoolscrosstied andRHRFPCinoperation ononeoftheunitsadequatecoolingofbothpoolswillbeachieved.
Forfurtherdiscussions seeSubsections 5.4.7.1.1.6, 5.7.2.1,c, 9.1.3.1c, and9.1.3.3.3.1.2.2Protection byMultipleFissionProductBarriersQrouII3.1.2.2.1 ReactorDesinCriterion 10Criterion Thereactorcoreandassociated coolant,control,andprotection systemsshallbedesignedwithappropriate margintoassurethatspecified acceptable fueldesignlimitsarenotRev.47,06/94 SSES-FSAR 3)In-service Inspection 4)ReactorVesselandAppurtenances 5)ReactorRecirculation System5.25.45.43.1.2.4.4 ReactorCoolantMakeupCriterion 33Criterion Asystemtosupplyreactorcoolantmakeupforprotection againstsmallbreaksinthereactorcoolantpressureboundaryshallbeprovided.
Thesystemsafetyfunctionshallbetoassurethatspecified acceptable fueldesignlimitsarenotexceededasaresultofreactorcoolantlossduetoleakagefromthereactorcoolantpressureboundaryandruptureofsmallpipingorothersmallcomponents whicharepartoftheboundary.
Thesystemshallbedesignedtoassurethatforonsiteelectricpowersystemoperation (assuming offsitepowerisnotavailable) andforoffsiteelectricpowersystemoperation (assuming onsitepowerisnotavailable) thesystemsafetyfunctioncanbeaccomplished usingthepiping,pumps,,andvalvesusedtomaintaincoolantinventory duringnormalreactoroperation.
DesinConformance Theplantisdesignedtoprovideamplereactorcoolantmakeupforprotection againstsmallleaksintheRCPBforanticipated operational occurrences andpostulated accidentconditions.
Thedesignofthesesystemsmeetstherequirements ofCriterion 33.Forfurtherdiscussion, seethefollowing sections:
2)3)4)5)6)ReactorCoolantPressureBoundaryLeakageDetection Systems5.2ReactorCoreIsolation CoolingSystem5.4Emergency CoreCoolingSystem6.3ReactorVessel-Instrumentation andControl7.6MakeupDemineralizer System9.2Condensate StorageandTransferSystem9'3.1.2.4.5 ResidualHeatRemovalCriterion 34Criterion Asystemtoremoveresidualheatshallbeprovided.
Thesystemsafetyfunctionshallbetotransferfissionproductdecayheatandotherresidualheatfromthereactorcoreataratesuchthatspecified acceptable fueldesignlimitsandthedesignconditions ofthereactorcoolantpressureboundaryarenotexceeded.
Rev.46,06/933.1-39 SSES-FSAR Suitableredundancy incomponents andfeatures, andsuitableinterconnections, leakdetection, andisolation capabilities shallbeprovidedtoassurethatforonsiteelectricpowersystemoperation (assuming offsitepowerisnotavailable) andforoffsiteelectricpowersystemoperation (assuming onsitepowerisnotavailable) thesystemsafetyfunctioncanbeaccomplished, assumingasinglefailure.DesinConformance RHRsystemprovidesthemeanstoremovedecayheatandresidualheatfromthenuclearsystemsothatrefueling andnuclearsystemservicing canbeperformed.
MajorRHRsystemequipment consistsoftwoheatfourmainsystempumps.Theequipment isassociated valvesandpiping,andtheinstrumentation areprovidedforpropersystemexchangers andconnected bycontrolsandoperation.
Twoindependent loopsarelocatedinseparateprotected areas.TheRHRsystemisdesignedforfourmodesofoperation:
a)Shutdowncoolingb)Suppression poolcooling(alsocontainment spray)c)Lowpressurecoolantinjection.
d)FuelPoolCoolingBothnormalacpowerandtheauxiliary onsitepowersystemprovideadequatepowertooperatealltheauxiliary loadsnecessary for,plantoperation.
Thepowersourcesfortheplantauxiliary powersystemaresufficient innumber,andofsuchelectrical andphysicalindependence thatnosingleprobableeventcouldinterrupt allauxiliary poweratonetime.Theplantauxiliary busessupplying powertoengineered safetyfeaturesandreactorprotection systemsandauxiliaries requiredforsafeshutdownareconnected byappropriate switching tothefouralignedstandbydiesel-driven generators locatedintheplant.Eachpowersource,uptothepointofitsconnection totheauxiliary powerbuses,iscapableofcompleteandrapidisolation fromanyothersource.Loadsimportant toplantoperation andsafetyaresplitanddiversified betweenswitchgear
- sections, andmeansareprovidedfordetection andisolation ofsystemfaults.Theplantlayoutisdesignedtoeffectphysicalseparation ofessential bussections, standbygenerators, switchgear, interconnections, feeders,powercenters,motorcontrolRev.46,06/933.1-40 SSES-FSAR centers,andothersystemcomponents.
Fourstandbydieselgenerators (A,B,C,andD)andasparedieselgenerator (E),whichcanbemanuallyrealigned asareplacement foranyoneoftheotherfourdieselgenerators areprovided.
Thesedieselgenerators supplyasourceofelectrical powerwhichisself-contained withintheplantandisnotdependent onexternalsourcesofsupply.Thestandbygenerators produceacpoweratavoltageandfrequency compatible withthenormalbusrequirements foressential equipment withintheplant.Thestandbydieselgenerator systemishighlyreliable.
Anythreeofthefivegenerators areadequatetostartandcarrytheessential loadsrequiredforasafeandorderlyshutdown.
TheRHRsystemisadequatetoremoveresidualheatfromthereactorcoretoensurefuelandRCPBdesignlimitsarenotexceeded.
Redundant reactorcoolantcirculation pathsareavailable toandfromthevesselandRHRsystem.UseofRHRintheFuelPoolCoolingmodewillnotadversely impacttheabilityofRHRtoperformReactorCoreCoolingfunctions asdiscussed inSubsections 5.4.7.1.1.6, 5.4.7.2.6c, 9.1.3.1c, and9.1.3.3.Redundant onsiteelectricpowersystemsareprovided.
ThedesignoftheRHRsystem,including itspowersupply,meetstherequirements ofCriterion 34.Forfurtherdiscussion, seethefollowing sections:
1)2)3)4)5)6)7)ResidualHeatRemovalSystemEmergency CoreCoolingSystemsEmergency CoreCoolingSystemsInstrumentation andControlAuxiliary PowerSystemStandbyacPowerSupplyandDistribution StationServiceWaterAccidentAnalysis5.46.37'8.38.39.215.03.1.2.4.6 Emergency CoreCoolingCriterion 35Criterion Asystemtoprovideabundantemergency corecoolingshallbeprovided.
Thesystemsafetyfunctionshallbetotransferheatfromthereactorcorefollowing anylossofreactorcoolantataratesuchthat(1)fuelandcladdamagethatcouldinterfere withcontinued effective corecoolingisprevented and(2)cladmetal-water reactionislimitedtonegligible amounts.Rev.46,06/933.1-41 SSES-FSAR Suitableredundancy incomponents andfeatures, andsuitableinterconnections, leakdetection, isolation, andcontainment capabilities shallbeprovidedtoassurethatforonsiteelectricpowersystemoperation (assuming offsitepowerisnotavailable) andforoffsiteelectricpowersystemoperation (assuming onsitepowerisnotavailable) thesystemsafetyfunctioncanbeaccomplished, assumingasinglefailure.Rev.46,06/933.X-(42)
SSES-FSAR DesinConformance Theemergency safeguard servicewatersystem,whichcomprises boththeEmergency ServiceWatersystemandtheResidualHeatRemovalServiceWatersystem,providescoolingwaterfortheremovalofexcessheatfromallstructures, systems,andcomponents whicharenecessary tomaintainsafetyduringallabnormalandaccidentconditions.
Theseincludethestandbydieselgenerators, theRHRpumpoilcoolersandsealwatercoolers,thecorespraypumproomunitcoolers,RCICpumproomunitcoolers,theHPCIpumproomunitcoolers,theRHRheatexchangers, RHRpumproomunitcoolers,emergency switchgear andloadcenterroomcoolersandthecontrolstructure chiller.ItalsoprovideswatertotheRHRpumpsandabovementioned roomunitcoolersduringaseismiceventtosupportoperation oftheRHRFuelPoolCooling(RHRFPC)mode.Make-upwatertotheSpentFuelPool(SFP)isprovidedduringaseismiceventinordertomake-upforevaporative lossesandfillingoftheSFPinsupportofRHRFPC.RHRSWprovidesthecoolingwatertotheRHRheatexchangers fortheRHRFPCmode.Theengineered safeguard servicewatersystemisdesignedtoSeismicCategoryIrequirements.
Redundant safetyrelatedcomponents servedbytheengineered safeguard servicewatersystemaresuppliedthroughredundant supplyheadersandreturnedthroughredundant discharge orreturnlines.Electricpowerforoperation ofredundant safetyrelatedcomponents ofthissystemissuppliedfromseparateindependent offsiteandredundant onsitestandbypowersources.Nosinglefailurerendersthesesystemsincapable ofperforming theirsafetyfunctions.
Referenced Subsections areasfollows:1)2)3)4)5)acPowerSystemsServiceWaterSystemEngineered ServiceWaterSystemRHRServiceWaterSystemUltimateHeatSink8.3.19.2.19.2.59.2.69.2.73.1.2.4.16 Inspection ofCoolingWaterSystemCriterion 45Criterion Thecoolingwatersystemshallbedesignedtopermitappropriate periodicinspection ofimportant components, suchasheatexchangers andpiping,toassuretheintegrity andcapability ofthesystem.Rev.46,06/933.1-51 SSES-FSAR DesinConformance Theengineered safeguard servicewaterandtheRBCCWsystemsaredesignedtopermitappropriate periodicinspection inordertoensuretheintegrity ofsystemcomponents.
Rev.46,06/933.1-(52)
SSES-FSAR DesinConformance NewFuelStoraeNewfuelisplacedindrystorageinthenewfuelstoragevaultthatislocatedinsidethereactorbuilding.
Thestoragevaultwithinthereactorbuildingprovides*adequate shielding forradiation protection.
Storageracksprecludeaccidental criticality (seeSubsection 3.1.2.6.3).
Thenewfuelstorageracksdonotrequireanyspecialinspection andtestingfornuclearsafetypurposes.
However,theracksareaccessible forperiodicinspection.
SentFuelHandlinandStoraeIrradiated fuelisstoredsubmerged inthespentfuelstoragepoollocatedinthereactorbuilding.
Fuelpoolwateriscirculated throughthefuelpoolcoolingandcleanupsystemtomaintainfuelpoolwatertemperature, purity,waterclarity,andwaterlevel.Storageracksprecludeaccidental criticality (seeSubsection 3.1.2.6.3).
Reliabledecayheatremovalisprovidedbythefuelpoolcoolingandcleanupsystem.Thepoolwateriscirculated throughthesystemwithsuctiontakenfromthepoolandisdischarged throughdiffusers atthebottomofthefuelpool.Poolwatertemperature ismaintained below125'Fwhenremovingthemaximumnormalheatload(MNHL)fromthepoolwiththeservicewatertemperature atitsmaximumdesignvalue.TheRHRsystemwithitssubstantially largerheatremoval"capacitycanbeusedasabackupforfuelpoolcoolingwhenheatloadslargerthanthecapability ofthefuelpoolcoolingsystemsareinthespentfuelpools.RHRalsoprovidesreliabledecayheatremovaltothespentfuelpoolsifthenormalfuelpoolcoolingsystemislostduetoaSeismicevent.Operation oftheRHRFuelPoolCooling(RHRFPC)modewillprovideseismicCategoryI,Class1Ecoolingtothespentfuelpoolssothatboilingofthespentfuelpoolsdoesnotoccurasaresultofaseismicevent.ESWprovidesSeismicCategoryI,Class1Emake-upinsupportofRHRFPC.Highandlowlevelswitchesindicatepoolwaterlevelchangesinthemaincontrolroom.Fissionproductconcentration inthepoolwaterisminimized byuseofthefiltersanddemineralizer.
Thisminimizes thereleasefromthepooltothereactorbuilding.
Rev.46,06/933.1-60 SSES-FSAR Thereactorbuildingventilation systemandthesecondary containment aredesignedtolimitthereleaseofradioactive materials totheenvironsandensurethatoffsitedosesarelessthanthelimitingvaluesspecified in10CFR100duringoperation andallaccidentconditions.
Nospecialtestsarerequired, becauseatleastonepumpandheatexchanger arecontinuously inoperation whilefuelisstoredinthepool.Duplicate unitsareoperatedperiodically tohandlehighheatloadsortoreplaceaunitforservicing.
Routinevisualinspection ofthesystemcomponents, instrumentation, andtroublealarmsareadequatetoverifysystemoperability.
TestingoftheRHRFPCmodeisaccomplished throughroutinetestingofthepumpsandheatexchangers insupportofothermodesofRHR.Thevalvessupporting theRHRFPCmodeareroutinely strokedtoconfirmproperoperation ofthevalvesfortheirRHRFPCmission.Rev.46,06/933.1-(61)
SSES-FSAR fuel.Theseinterlocks precludeanyloadsuspended fromthiscranefromtippingoveronthestoredfuelintheeventofacranefailure.The5tonauxiliary hooksuspended fromthesamecranetrolleyisprevented frompassingoverstoredfuelwhenfuelhandlingisnotinprogressbyadministrative controls'here arenoplannedtransfe'rs ofloadsheavierthananewfuelelementoverthestoredfuel.(3)
Reference:
PositionC.8.ASeismicCategoryImakeupwatersupplyfromeachemergency servicewaterloopispermanently connected to,eachspentfuelpoolbytwoindependent SeismicCategoryIpipingroutes.Themake-upisprovidedforfillingthe-spentfuelpooltotheproperleveltosupportoperation oftheRHRfuelpoolcoolingmode,andtoprovideformake-upfromevaporative lossesduringcoolingbyRHR.Themake-uprateissizedbasedonboilingsoastobeconservative.
ThenormalmakeupsystemtothefuelpoolisnotSeismicCategoryI.ReulatoGuide1.14REACTORCOOLANTPUMPFLY-WHEEL INTEGRITY Revision1Auust1975Notapplicable.
ReulatorGuide1.15-TESTINGOFREINFORCING BARSFORCATEGORYICONCRETESTRUCTURES Revision1December281972Testingofreinforcing barsforCategoryIconcretestructures isincompliance withthisregulatory guide.ReulatorGuide1.16-REPORTING OFOPERATING INFORMATION-APPENDIX ATECHNICAL SPECIFICATIONS Revision4Auust1975Inlieuofthepositions statedinthisRegulatory Guide,thereporting ofoperating information fortheSusquehanna SEScomplieswithTechnical Specifications and10CFR50.73.
ReulatorGuide1.17PROTECTION OFNUCLEARPOWERPLANTSAGAINSTINDUSTRIAL SABOTAGEJune1973Inlieuofthepositions statedinthisregulatory guide,theprotection ofSusquehanna SESagainstindustrial sabotagecomplieswith10CFR73.Rev.46,06/933.13-6 SSES-FSAR
Reference:
PositionC.l.dandC.l.g.Thenormalspentfuelpoolcoolingsystemisnon-seismic CategoryI.IfaseismiceventwouldoccurcoolingofthespentfuelisachievedbyuseoftheRHRFuelPoolCooling(RHRFPC)modeasdescribed insections5.4.7.1.1
',5.4.7.2.6c, 9.1.3.1,and9.1.3.3.EitherorbothoftwoSeismicCategoryIESWmakeupwatersuppliestoeachpoolcanprovidemake-upinsupportoftheRHRFPCmode.Additionally, ESWiscapableofsupplying make-upfortheboilingspentfuelpoolanalysisasdescribed inAppendix9A.
Reference:
PositionC.l.e.TheMainSteamSystem(MSS)beyondtheouterisolation valvesuptoandincluding theturbinestopvalvesandallbranchlines21/2in.indiameterandlarger,uptoandincluding thefirstvalve(including theirrestraints) arenotclassified SeismicCategoryI;becauseportionsofthepipeareroutedinanon-Seismic CategoryIbuilding(theTurbineBuilding).
However,theturbinebuildinghasbeendesignedtowithstand anSSEasstatedinSubsection 3.7b.2'.Furtherdescription oftheturbinebuildingisgiveninSubsection 3.8.4.1;applicable loadcombinations aregiveninTable3.8-10.Thesubjectpipingisdesignedinaccordance withASMESectionIII,Class2requirements fortheOBEandSSEasdescribed inSubsection 10.3.3.
Reference:
PositionC.l.h.Thecomponent coolingwaterportionsofthereactorrecirculation pumpsarenotSeismicClassIsincetheydonotinvolveasafetyfunction.
Reference:
Paragraph C.2oftheRegulatory Guide.Itemswhichwouldotherwise beclassified non-seismic categoryI,"butwhosefailurecouldreducethefunctioning" ofitemsimportant tosafety"toanunacceptable safetylevel"aretobe"designed andconstructed sothattheSSEwouldnotcausesuchfailure."
Inaddition, Paragraph C.4oftheguiderequiresthatthe"pertinent qualityassurance requirement ofAppendixBto10CFRPart50shouldbeappliedtothesafetyrequirements" ofsuchitems.Bothof'hesepositions areconsidered tobeadequately metbyapplyingthefollowing practices tosuchitems:06/933.13-10 SSES-FSAR (a)Designanddesigncontrolforsuchitemsarecarriedoutinthesamemannerasthatforitemsdirectlyimportant tosafety.Thisincludestheperformance ofappropriate designreviews.Rev.46,06/933.13-(11)
SSES-FSAR TABLE3.2-1Continued)
Page9.Principal Components (34*)FSARSectionSourceof~Su1(1)*Loca-tion(2)*QualityGroupClassi-fication(3)*SafetyClass(4)*Principal Construc-tionCodesandStandards (5)*SeismicCategonr(6)*QualityAssurance Reenirement Cmmmnte(7)**UnderReactorVesselServiceEuintEquipment handlingplatformCRDhandlingequipment FuelPoolCooli5CleanuSstemHeatexchangers PumpsSkimaersurgetanksFilterdemineralizer vesselsResinandprecoattanksCoolinglooppipingandvalvesdownstream ofvalve1-53-001.
2-53-001RHRintertiepipingandvalvesEmergency servicewatermakeuppipingandvalvesOtherpipingandvalvesCoolinlooipinustreamofvalvel-53-Ii0(.
2-5-II01fromskirmersurgetankRadioactive WasteManaementLiuidWasteNanaementSstemsCentrifugal pumpsAtmospheric Tanks9.1.49.1.311.2GEGER/RW/T0RW/T0OtherXOtherXOtherIII-3.TB1ACOtherIII-3,OtherIII-3OtherVIII-1OtherAPI-650OtherIII-3OtherII1-3OtherIII-3OtherB31.1.0OtherIII-3OtherIII-3OtherVIII-1/III-3INA19.3146,5519.31.56I31.2231.22Rev.47,06/94*RefertotheGeneralNotesattheendofthistable.
SSES-FSAR TABLE3.2-1SSESDESIGNCRITERIASUMMARY(Continued)
Page5254)Thedieselgenerator jacketwatercoolers(OE507BandOE507D)utilizeanASMESectionVIIIreplacement tubebundleinaccordance withtheguidanceofNRCGenericLetter89-09.55)Thefollowing manuallyoperatedvalvesprovideafillablevolumeforuseoftheRHRFPCmode.Thefollowing manuallyoperatedvalves,whichareintheseismically analyzedsectionsofpipe,requireacapability tobeclosedfollowing aseismicevent.Thesevalveshavebeenanalyzedtodemonstrate thattheywillbecapableofclosurefollowing aseismicevent:SpentFuelPoolto153018A/B (253018A/B),
FuelPoolGateDrainto153038(253038),
andReactorWellDiffuserto153030A/B (25303OA/B).
Thefollowing manuallyoperatedvalves,whichareinseismically analyzedsectionsofpipe,haveapostseismiceventfunctiontoremainintheclosedposition:
ReactorWellDrainto153031(253031),
ReactorWellDrainto153032(253032),
ReactorWellDrainto153062(253062),
DryerSeparator PoolDrainto153040(253040),
DryerSeparator PoolDrainto153041(253041),
CaskPitGateDrainto153050(253050),
CaskPitDrainto153054(253054),
CaskPitDrainto053084&,253800,andCaskPitDiffuserto053025.56)Theportionsofpipingbetweenthesurgetankuptoandincluding valvesHV15308(25308),153076(253076),
and153064A/B (253064A/B)
'havebeenanalyzedtoshowthattheywillremainintactfollowing aseismicevent.Thesevalveshavebeenanalyzedtodemonstrate thattheywillbecapableofclosure(orremaining closed)following aseismicevent.Closureofthesevalvesisnecessary toprovideafillablevolumeforuseoftheRHRFPCmode.TheSkimmerSurgeTankdrainlinevalves,153065A(253065A),
arenormallyclosedandassumedtoremainclosedduringaseismicevent.Rev.47,06/94 SSES-FSAR thecapacityofasingleRHRheatexchanger andrelatedservicewatercapability.
Figure5.4-12showstheminimumtimerequiredtoreducevesselcoolanttemperature to212'FusingoneRHRheatexchanger andallowing2hoursforflushing.
5.4.7.1.1.2 LowPressureCoolantIn'ection LPCIModeThe,functional designbasesforthe,LPCImodeistopumpatotalof21,300gpmofwaterperloopusingtheseparatepumploopsfromthesuppression poolintothecoreregionofthevessel,whenthevesselpressureis20psidoverdrywellpressure.
Injection flowcommences at280psidvesselpressureabovedrywellpressure.
Theinitiating signalsare:vessellevel1.0feetabovetheactivecoreordrywellpressuregreaterthanorequalto1.69psigcoincident withalowreactorpressure.
Thepumpswillattainratedspeedin27secondsandinjection valvesfullyopenin40seconds'.4.7.1.1.3 SuressionPoolCoolinModeThefunctional designbasisforthesuppression poolcoolingmodeisthatitshallhavethecapacitytoensurethatthebulksuppression pooltemperature immediately afterablowdownshallnotexceed207'F.5.4.7.1.1.4 Containment SraCoolinModeThefunctional designbasisforthecontainment spraycoolingmodeisthatthereshouldbetworedundant meanstosprayintothedrywellandsuppression poolvaporspacetoreduceinternalpressuretobelowdesignlimits.5.4.7.1.1.5 ReactorSteamCondensin ModeThissectionhasbeenintentionally deleted.5.4.7.1.1.6 FuelPoolCoolinModeThefunctional designbasisforthefuelpoolcoolingmodeisasfollows:a)TheRHRFPCmodeisdesignedandoperatedtoprovidecoolingsuchthatthefuelpoolwillbemaintained atorbelow125FwhentheEmergency HeatLoad(EHL)isRev.46,06/935.4-33 SSES-FSAR residentinanisolatedfuelpool.TheEHLcanberemovedwithaRHRSWinlettemperature of91'FwithonlyoneRHRpumpandheatexchange.
Forcrosstied fuelpools,oneRHRpumpandheatexchanger inoneunitincombination withthenormalFuelPoolCoolingsystemfromtheadjacentunitissufficient tomaintainthefuelpoolsatorbelow125'FwiththeEHLresidentinonefuelpoolandfuelatthescheduled offloadrateintheotherfuelpool.Thisfunctionisdescribed inSections9.1.3.band9.1.3.2.b)TheRHRFPCmodeisdesignedandoperatedtoprovidesufficient coolingtopreventfuelpoolboilingintheeventthataseismiceventcausesanextendedlossofbothunits'ormal fuelpoolcoolingsystems.Thiscapability existsforbothcrosstied andisolatedfuelpools.WhenoneRHRpumpisoperatedintheRHRFPCmode,thespentfuelpoollevelmustberaisedtoaminimumlevelabovetheweirsinordertosupportthedesignflowrateforthismode.Additional detailsdescribing thismodeofRHRarecontained inSections5.4.7.2.6c, 9.1.3.1c, 9.1.3.2,and9.1.3.3.5.4.7.1.2 DesignBasisforIsolation ofRHRSystemfromReactorCoolantSstemThelowpressureportions, oftheRHRsystem,areisolatedfromfullreactorpressurewhenevertheprimarysystempressureisabovetheRHRsystemdesignpressure.
SeeSubsection 5.4.7.1.3 forfurtherdetails.Inaddition, automatic isolation mayoccurforreasonsofvesselwaterinventory retention whichisunrelated tolinepressurerates.(SeeSubsection 5.2.5foranexplanation oftheLeakDetection Systemandtheisolation signals.)
ReactorCoolantpressureboundaryvalvesaresubjecttoinservice inspection leakagetestingrequirements asprovidedin10CFR50.55a (seeSubsection 3.9.6).TheRHRpumpsareprotected againstdamagefromacloseddischarge valvebymeansofautomatic minimumflowvalves,whichopenonlowmainlineflowandcloseonhighmainlineflow.5.4.7.1.3 DesinBasisForPressureReliefCaacitThereliefvalvesintheRHRsystemaresizedononeofthreebases:(1)ThermalreliefonlyRev.46,06/935.4-34 SSES-FSAR (2)Valvebypassleakageonly(3)Controlvalvefailureandthesubsequent uncontrolled flowwhichresults.Transients aretreatedbyitems(1)and(3);item(2)abovehasresultedfromanexcessive leakpast'isolation valves.F055ARBshallbesizedtomaintainupstreampipingat450psigand10percentaccumulation withF051andF052fullyopenandareactorpressureequaltothelowestNuclearBoilersafety/relief valvespringsetpoint.F097shallbesizedtomaintainupstreampressureat180psigand10percentaccumulation withbothPCVF053A&Bfailedopen.F030A,B,C,andD,F025AandB,F029,F126,andF087shallbesetatthedesignpressurespecified intheprocessdatadrawingplus10percentaccumulation.
Redundant interlocks preventopeningvalvestothelowpressuresuctionpipingwhenthereactorpressureisabovetheshutdownrange.Thesesameinterlocks initiatevalveclosureonincreasing reactorpressure.
Inadditionahighpressurecheckvalvewillclosetopreventreverseflowfromthereactorifthepressureshouldincrease.
Reliefvalvesinthedischarge pipingaresizedtoaccountforleakagepastthecheckvalve.5.4.7.1.4 DesignBasisWithRespecttoGeneralDesinCriteria5TheRHRsystemforeachunitdoesnotshareequipment orstructures withtheothernuclearunitexceptfortheSpentFuelPoolsasdiscussed inSubsection 9.1.3.3.TheyalsosharethecommonEmergency ServiceWaterSystem.SharingofthissystemwithrespecttoGeneralDesignCriteria5isdiscussed inSection3.1.2.1.5.
Rev.46,06/935.4-(35)
SSES-FSAR performflushingwillcauseinjection ofnon-reactor gradewaterintothereactorpressurevesselbutwillnotaffectperformance oftheRHRshutdowncoolingsystem.Attheendofthisnominalflush,thetestablecheckbypassvalvemaybeopenedintheshutdownreturnlineandvesselwateris-permitted toentertheupperportion'.,of thechosenlooptoprewarmi'ffluent isdirectedtoradwasteandatemperature elementisusedtocontroleffluenttemperature.
Thetestablecheckbypassvalveisclosedandvesselsuctionvalvesareopenedtoallowprewarming ofthelowerhalfoftheshutdownloopwitheffluentdirectedtoradwasteasbefore.Theradwasteeffluentvalvesareclosed,theheatexchanger bypassvalvesopened(theexchanger valveswereclosedaftertheinitialcoldwaterflush),thenthepumpstartsataregulated flowthroughreturnvalveF017.Afterwaitingseveralminutestopermitloopinternalstability tobeestablished theservicewaterpumpisstarted,theservicewatervalvesareopened,theheatexchanger inletandoutletvalvesareopenedandcooldownofthevesselisinprogress.
Cooldownrateissubsequently controlled viavalvesF017(totalflow)andF048(heatexchanger bypassflow).Alloperations areperformed fromthecontrolroomexceptforopeningandclosingoflocalflushwatervalves.Themanualactionsrequiredforthemostlimitingfailurearediscussed inSubsection 5.4.7.1.5.
b.SteamCondensin C.Thissectionhasbeenintentionally deleted.FuelPoolCoolinModeOperation ofRHRinthefuelpoolcoolingmoderequiresmanualactionstobeperformed bothinthecontrolroomandlocally.Thesystemwillalsoberequiredtobefilledandvented,whichwillrequirethemanipulation ofvarioussmallmanualvalves.Thefillingoperation mayalsoincludeoperation oftheESWsystemintheeventthenormalfillsystemsareunavailable.
Theseactionsaredescribed inandcontrolled byplantprocedures.
5.4.7.3Performance Evaluation Thermalperformance oftheRHRheatexchangers isbasedontheresidualheatgenerated at20hoursafterrodinsertion, a125'Fvesseloutlet(exchanger inlet)temperature, andtheflowoftwoloopsinoperation.
Becauseshutdownisusuallyacontrolled operation, maximumservicewatertemperature lessRev.46,06/935.4-39 SSES-FSAR 10'Fisusedastheservicewaterinlettemperature.
Thesearenominaldesignconditions; iftheservicewatertemperature ishigher,theexchanger capabilities arereducedandtheshutdowntimemaybelongerandviceversa.5.4.7.3.1 ShutdownWithAllComonentsAvailable Notypicalcurveisincludedheretoshowvesselcooldowntemperatures versustimeduetotheinfinitevarietyofsuchcurvesthatmaybedueto:(1)cleansteamsystemsthatmayallowthemaincondenser tobeusedastheheatsinkwhennuclearRev.46,06/935.4-(40)
SSES-FSAR f)Theplateswillbewashedinamildabrasiveanddetergent
- solution, thenrinsedincleanwaterand/oracetone.Theplateswillbedriedina175'Fovenfora4hours,followedby4hoursina300'Fovenand4additional hoursina500'Foven.Theplateweightwillbedetermined, atroomtemperature, following eachdryingi.'nterval.
Dryingmaybediscontinued whennofurtherweightlossoccurs.g)Eachplatewillbeweighedanddetermine weightchange.h)Reperform stepge.i)Alldatawillberecorded, including pHvalues,forfuturecomparison.
9.1.3SPENTFUELPOOLCOOLINQANDCLEANUPSYSTEM9.1.3.1DesinBasesTheFuelPoolCoolingandCleanupSystem(FPCCS)isdesignedandoperatedwiththefollowing considerations:
a)Maintaining thefuelpoolwatertemperature below125'F.TheheatloadwhichservedasthebasisfortheFPCCSdesignisbaseduponfillingthepoolwith2840fuelassemblies fromnormalrefueling discharges andtransferred tothefuelpoolwithin160hoursaftershutdown.
Tables9.1-2aand9.1-2bshowtheoriginally assumeddischarge scheduleandheatload.Table9.1-2eshowsanupdateddischarge schedule.
b)Duringanemergency heatload(EHL)condition, oneRHRpumpandheatexchanger areavailable forfuelpoolcooling.TheEHLcondition occurswhenthespentfuelracksofonespentfuelpoolcontain2850fuelassemblies including afullcoredischarged tothepoolwithin250hoursaftershutdown(controlrodsinserted).
Tables9.1-2cand9.1-2dshowthedischarge scheduleandheatloadthatwasassumedforthesystem'sdesignforthiscondition forUnits1and2.Table9.1-2fshowsanupdateddischarge schedule.
TheRHRFuelPoolCooling(RHRFPC)Modewillmaintaintheisolatedfuelpoolwatertemperature, (withtheheatloadof3.39x10'TU/hr) atorbelow125'Fwithorwithoutassistance fromtheFPCCSundernormalrefueling conditions.
WhenthedecayheatloadofthespentfueldropstothelevelforwhichtheFPCCSisdesigned, theRHRsystemmaybedisengaged.
Forcrosstied spentfuelpools,theRHRFPCmodeinoneunitincombination withthenormalFuelPoolCoolingSystemoftheotherunitwillmaintainthecrosstied fuelRev.48,12/949.1-21 SSES-FSAR poolsatorbelow125'FwiththeEHLinonepoolandfuelatthenormalscheduled offloadrateintheotherpool.c)Following aseismicevent,thenormalFuelPoolCoolingsystemispostulated tobeunavailable duetoitsNon-SeismicCategoryI,Non-Class 1Epowerdesign.IfsuchaneventweretooccurtheRHRFuelPoolCooling(RHRFPC)modewouldbeusedtoprovidecoolingtothespentfuelpoolstopreventboiling.Allpipingandcomponents oftheRHRFPCmodeareSeismicCategory1,QualityGroupBorCconstructed toASMESectionIIIstandards.
TheRHRsystemisClass1Epoweredandbothloopshaveseparatepowersupplies.
TheRHRFPCsystemishardpiped andrequiresoperation ofseveralmanualvalves.(whichareaccessible following aseismicevent)toestablish theflowpath.
Inaddition, othermanualandmotoroperatedvalvesmustbeoperatedinordertoassureproperoperation oftheRHRFPCmode.Properoperation ofallactivecomponents intheRHRFPCmodeisconfirmed onaperiodicbasisinaccordance withplantprocedures.
TheRHRpumpsuctionpathfortheFuelPoolCoolingmodeissharedwiththeShutdownCoolingmodeofRHR.Consequently, ShutdownCoolingandFuelPoolCoolingcannotbeperformed concurrently onagivenunit.However,Alternate ShutdownCoolingandFuelPoolCoolingcanbeperformed concurrently sincedifferent suctionsourcesareused.Appendix9Acontainsanevaluation ofaboilingspentfuelpoolforaNon-Seismic CategoryIFuelPoolCoolingsystem.Boilingofthespentfuelpool(s)wouldnotoccurduringaseismiceventduetouseoftheRHRFuelPoolCoolingsystemasabackupSeismicCategoryIFuelPoolCoolingsystem.TheRHRFPCmodecanbeplacedintoservicewellinadvanceofthepostulated timetoboilof25hours(seeSubsection 9.1.3.3).
d)Tomaintainthewaterclarityandqualityinthepoolsasfollowstofacilitate underwater handlingoffuelassemblies andtominimizefissionandcorrosion productbuildupthatposearadiological hazardtooperating personnel:
Conductivity pHChloride(asCl)3mircromho/cm at25'C5.3-7.5at25'C0.5ppmRev.48,12/949.1-22 SSES-FSAR Heavyelements(Fe,Cu,Hg,Ni) 0.1ppmTotalinsolubles 1ppm9.1.3.2SstemDescritionEachreactorunitisprovidedwithitsownFPCCSasshownonFigures9.1-7and9.1-8.Thesystemcoolsthefuelstoragepoolwaterbytransferring thedecayheatoftheirradiated fuelthroughheatexchangers totheservicewatersystem.Waterclarityandqualityinthefuelstoragepools,transfercanals,reactorwells,dryer-separator pools,andshippingcaskpitaremaintained byfiltering anddemineralizing.
TheFPCCSconsistsoffuelpoolcooling'umps, heatexchangers, skimmersurgetanks,filterdemineralizers, associated piping,valves,andinstrumentation.
EuimentDescritionTable9.1-1showsthedesignparameters oftheFPCCSequipment.
'heseismicandqualitygroupclassifications oftheFPCCScomponents arelistedinSection3.2.Oneskimmersurgetankforeachunitcollectsoverflowwaterfromskimmerdrainopeningswithadjustable weirsatthewatersurfaceelevation ofeachpoolandwell.Thecommonshippingcaskpitwateroverflows tobothunits'kimmer surgetanks.Wavesuppression scuppersalongtheworkingsideofthefuelpoolsalsodraintotheskimmersurgetanks.Theskimmeropeningsinthepoollinersareprotected withawiremeshscreentopreventfloatingobjectssuchasthesurfacebreakerviewingaidsfromenteringthesurgetanks.Theadjustable weirplatesaresetaccording totherequiredcoolingflow,desiredflowpattern,andwatershielding needs.Theskimmersurgetankprovidesasuctionheadforthefuelpoolcoolingpumpsandabuffervolumeduringtransient flowsinthenormallyclosedloopFPCCS.Itprovidessufficient livecapacityforthreedays'ormal evaporative lossfromthefuelpoolwithoutmakeupfromthecondensate transfersystem.Aremovable objectretention screeninthetankisaccessible throughtheflangedtanktop.Tanklevelindication andalarmsonacontrolpanelontherefueling floorand/orthevicinityofthefuelpoolcoolingpumpsannouncewhentheremotemanualmakeupvalvesmustbeopenedorwaterdrainedfromthesystem.Rev.46,06/939.1-23
)
SSES-FSAR ThefuelpoolcoolingpumpsarestoppeduponalowtanklevelsignalsThreefuelpoolheatexchangers pipedinparallelarelocatedinthereactorbuildingbelowthesurgetankbottomelevation.
Theshellsideissubjected tothestaticheadoftheskimmersurgetanklevelonly.Thisisaminimumof5psilowerthanthetubesideservicewaterpressure, thusminimizing thepossibility ofradioactive contamination oftheservicewatersystem(seeSubsection 9.2.1)fromatubeleak.Thenumberofheatexchangers inservicedependsonthedecayheatloadfromirradiated fuelinthespentfuelpool.Thecommoninletandeachheatexchanger outlettemperature arerecordedandhightemperature alarmedonalocalcontrolpanel.Threefuelpoolcoolingpumpspipedinparallelareplacedinserviceinconjunction withtheheatexchangers.
Theytakesuctionfromtheheatexchangers anddevelopsufficient headtoprocessapartialsystemflowthroughthefilterdemineralizers andtransferitcombinedwiththebypassflowtothediffuserpipesatthebottomofthepools.Thepumpcontrols, discharge pressureindicators, flowindicator, andalarmsforlowflowandlowdischarge pressureareprovidedonalocalcontrolpanel.Thepumpstripindividually uponlowNPSH.Threefuelpoolfilterdemineralizers arepipedinparallel.
Onefuelpoolfilterdemineralizer isnormallyassociated witheachFPCCSwiththethirdoneinstandby.Thedesignflowperfilterdemineralizer islessthanthetotalsystemflow.Partofthecooledwateristherefore bypassing atamanuallyadjustable rate.Rev.46,06/939.X-(24)
SSES-FSAR skimmersurgetanks'uring periodswhentheheatinthepoolisgreaterthanthecapacityofthefuelpoolcoolingsystem(suchthatacceptable fuelpooltemperatures cannotbemaintained),
eg,storingofafullcoreofirradiated fuelshortlyaftershutdown, theRHRsystemcanbeusedtodissipate thedecayheat.OneRHRpumptakessuctionfromanintertielinetotheskimmersurgetankanddischarges throughoneRHRheatexchanger totwoindependent diffusers atthefuelpoolbottom.Withthespentfuelpool(s)filledtoaheightapproximately 7.5inchesabovetheweirs,theskimmersurgetankprovidessufficient suctionheadtoanRHRpumpintheRHRFuelPoolCooling(RHRFPC)mode.Makeupwatertoreplenish evaporative andsmallleakagelossesfromthepoolsisprovidedfromthecondensate transferstoragetankintotheskimmersurgetankbyopeningaremotemanualvalve.ASeismicCategoryIlinefromeachofthetwoemergency servicewaterloopsisconnected totheRHRintertiediffuserlinesofeachfuelpool,allowingforemergency makeupinsupportofRHRFPCorduringpostulated boilingofthepoolwaterasdescribed inAppendix9A.Themanualsupplyvalvesintheseemergency makeuplinesareaccessible fromelevations belowtherefueling floor.9.1.3.3SafetEvaluation AtFPCCSdesignconditions wherethepoolheatloadis12.6MBTU/HRandservicewatertemperature is95'FtheFPCCSwillmaintainthefuelpoolwaterlessthan125'F.Atimprovedservicewatertemperature conditions, theFPCCScanmaintainthefuelpoolwaterlessthan125'Fwithlargerheatloadsinthepool.Thiscondition occursduringrefueling outages.Whenthiscondition existsthepoolismonitored toassureadequateFPCCScapacityexists.WhentheFPCCScannotmaintainthepooltemperature lessthan125'F,theRHRsystemintheFuelPoolCoolingMode(RHRFPC)canbeconnected tothepoolstomaintainpooltemperatures below125'FbytheRHRFPCmode.ATEHLconditions (33.9MBTU/HR),
RHRFPCcanmaintainthepooltemperature below125'Fwithspraypondwatertemperatures belowTechnical Specification limits.Poolconfiguration willbemaintained duringtheoutagesequencesothatthecalculated timetoboilisgreaterthan25hours.ASeismicCategoryImakeupisprovidedbya2in.linefromeachemergency servicewater(ESW)looptotheRHRfuelpooldiffusers, thusproviding redundant flowpathsfromareliableRev.46,06/939.1-27 SSES-FSAR sourceofwater.ThedesignmakeupratefromeachESWloopisbasedonreplenishing thepostulated boil-offfromtheMNHLineachfuelpoolfor30daysfollowing thelossoftheFPCCScapacity.
ThisprovidesacapacityfarinexcessofwhatwouldberequiredbytheRHRFPCmodeinresponsetoalossofnormalfuelpoolcoolingduetoaseismicevent.Allpipingandequipment sharedwithorconnecting totheRHRintertieloopareSeismicCategoryI,QualityGroupC,orequivalent, andcanbeisolatedfromanypipingassociated withthenon-Seismic CategoryIQualityGroupCfuelpoolcoolingsystem.DuetoitsNon-Seismic CategoryI,Non-Class lEpowerdesign,theconsequences ofaseismiceventarerequiredtobeanalyzedfortheFPCsystem.Inresponsetothisevent,theRHRFPCmodewillbeusedtopreventboilingfromoccurring; however,anon-mechanistic evaluation ofboilingofbothspentfuelpoolsiscontained inAppendix9Ainordertoconservatively boundtheradiological consequences.
Thespentfuelpoolsarenormallymaintained inacrosstied configuration duringdualunitoperation andrefueling outages.Thisassuresthatthetimetoboilfollowing alossofnormalfuelpoolcoolingisaminimumof25hours;however,inthisconfiguration thetimetoboilistypically muchgreaterthantheminimum25hours.The25hourtimetoboilminimumwouldonlybeapproached shortlyafteraunitisshutdownforrefueling.
Aftercompletion ofarefueling outage,whenbothunitsareatpower,thetimetoboilistypically ontheorderof50hours.Thecrosstied configuration allowsuseofeitherunit'ssystems(normalSFPCoolingorRHRFPC)tocoolthepools,thusproviding fuelpoolcoolingredundancy.
Crosstied spentfuelpoolsalsoprovideredundancy forthelevelinstrumentation inthecontrolroom.Thisinstrumentation isdesignedtooperatefollowing anOperating BasisEarthquake andunderboilingspentfuelpoolconditions andisexpectedtoremainfunctional.
Whilenotclassified asClass1Eequipment, theinstruments receivepowerfromindependent Class1EpowersuppliesthatareDieselGenerator backed.Shouldaseismiceventoccurduringdualunitpoweroperation withcrosstied pools,adequatereactorcorecoolingwillbeprovidedandspentfuelpoolboilingwillbeprevented.
OnlyoneloopofRHRisnecessary toprovidelongtermdecayheatremovalperreactorvessel.Similarly, onlyoneloopofRHRisnecessary toprovidelongtermdecayheatremovaltocrosstied spentfuelpools.Sinceeitherunit'sRHRsystemcanprovidecoolingtobothunitsspentfuelpoolswiththepoolscrosstied, afailureofoneloopofRHRinoneoftheunitswouldstillallowasufficient numberofloopstocoolbothRev.46,06/939.1-28 JI SSES-FSAR reactorsandthespentfuelpools.Inthiscase,theunitproviding spentfuelpoolcoolingwouldutilizeAlternate ShutdownCoolingforlong-term decayheatremovalfromthereactor.TheotherunitwouldutilizethenormalShutdownCoolingmode.Duringspecificplantevolutions, suchastransferoffuelintofuelcasks,thepoolswillnotbecrosstied.
Theseevolutions willbeprocedurally controlled toensurethatsufficient coolingsystemsareavailable giventheplantconfiguration atthetimeoftheevolution.
Anevaluation oftheimpactsofoperating theRHRFPCmodeontheUltimateHeatSink(UHS)wasperformed asaseparateevaluation oftheminimumheattransfercasediscussed inSubsections 9.2.7.3.1 and9.2.7.3.6.
Theresultsofthisevaluation indicatethatthespraypond(UHS)willbemaintained belowthedesignmaximumtemperature underworstcaseaccidentconditions.
Additional detailsonthedesignoftheRHRFPCmodeareprovidedinSections5.4.7.1.1.6, 5.4.7.2.6C, and9.1.3.1C.Provisions tominimizeandmonitorleakagefromthefuelpoolaredescribed inSubsection 9.1.2.3.Makeupforevaporative andsmallleakagelossesfromthefuelpoolisnormallysuppliedfromthecondensate transfersystemtotheskimmersurgetanksofeachunit.Theintermittent flowrateisapproximately 50gpmtoeachsurgetank.Thewaterlevelinthespentfuelstoragepoolismaintained ataheightwhichissufficient toprovideshielding forrequiredbuildingoccupancy.
Radioactive particulates removedfromthefuelpoolarecollected infilterdemineralizer unitsinshieldedcells.Forthesereasons,,the exposureofstationpersonnel toradiation fromthespentfuelpoolcoolingandcleanupsystemisnormallyminimal.Furtherdetailsofradiological considerations aredescribed inChapter12.Anevaluation oftheradiological effectofaboilingfuelpoolispresented inAppendix9A.9.1.3.4InsectionandTestinReuirements Nospecialtestsarerequiredbecauseatleastonepump,heatexchanger, andfilterdemineralizer arecontinuously inoperation whilefuelisstoredinthepool.Theremaining components areperiodically operatedtohandleincreased heatloadsduringrefueling.
Rev.46,06/939.1-(29)
SSES-FSAR Thepoollinerleakdetection drainvalvesareperiodically openedandtheleakrateestimated bythevolumetric method.Gasordyepressuretestingfrombehindthelinerplatemaybeperformed tolocatealinerplateleak.Routinevisualinspection ofthe-systemcomponents, instrumentation, andtroublealarmsisprovidedtoverifysystemoperability.
Components andpipingoftheFPCCSdesignedperASMEBoilerandPressureVesselCode,SectionIII,Class3arein-service inspected asdescribed inSection6.6.Thesystemwillbepreoperationally testedinaccordance withtherequirements ofChapter14.Rev.46,06/939.j.-(30)
SSES-FSAR switchgear andloadcenterroomcoolers,whicharenormallysuppliedbythecontrolstructure chilledwatersysteminUnit1orthedirectexpansion (DX)coolingsysteminUnit2)requiredduringnormalandemergency conditions necessary tosafelyshutdowntheplant.TheESWSisdesignedtotakewaterfromthespraypond(theultimateheatsink),pumpittothevariousheatexchangers andreturnittothespraypondbywayofanetworkofspraysthatdissipate theheattotheatmosphere, TheESWSisrequiredtosupplycoolingwaterto:a)TheRHRpumproomunitcoolerandthemotorbearingoilcoolerofeachRHRpumpduringallmodesofoperation oftheRHRsystem.b)Alltheheatexchangers associated withthefourdieselgenerators alignedtothesystemduringoperation andtestmodes,exceptforthegovernoroilcoolers.c)Theroomcoolersforthecorespray(CS)pumps,thehighpressurecoolantinjection (HPCI)pumps,andreactorcoreisolation cooling(RCIC)pumpsduringtheoperation ofthesesystems.d)Thecontrolstructure chiller,theUnit2emergency switchgear coolingcondensing unit,reactorbuildingclosedcoolingwater(RBCCW)heatexchangers, andtheturbinebuildingclosedcoolingwaterheatexchanger (TBCCW)duringemergency operation.
e)Thespentfuelpoolstoprovidemake-upforevaporative lossesduringoperation ofthenormalfuelpoolcoolingsystemorRHRFuelPoolCooling(RHRFPC)mode,aswellas,fillingthespentfuelpoolsinsupportofRHRFPC.TheESWSisalsocapableofsupplying make-upforpostulated boilingconditions asdescribed inAppendix9AforaSeismicEvent.TheESWSstartsautomatically withinapprox.40-100secondsafterthedieselgenerators receivetheirstartinitiation signal.TheESWScanalsobestartedmanuallyfromeitherthemaincontrolroomorfromoneofthetworemoteshutdownpanels.(i.e~,ESWloopAcanonlybestartedfromtheUnit2remoteshutdownpanelandESWloopBcanonlybestartedfromtheUnit1remoteshutdownpanel.)Rev.47,06/949.2-13
~o
~~~~~~SSES-FSAR Inordertoavoidhavingunacceptable voltagesduetotheRHRorCSpumpsstartingsimultaneously withtheESWpumps,theESWloadsequencetimerisreinitialized, butonlyiftheESWpumpshavenotstartedbeforetheRHRorCSpumps.TheESWSisdesignedtooperateduringanyofthefollowing conditions:
a)LossofoffsitepowerRev.47,06/949.2-(14) a~
~tI~~~SSES-FSAR TABLE9.2-3DEFINITION OFESWFLOWSFORUNITS1842Page1of2Component No.ofUsersPerLoopU1U2Min.Req'dESWFlowPerUser(GPM)Min.Req'd.ESWLoopFlowForDBAand1LoopFailedTypicalMin.ESWLoopF)owNon.Accident w/1LoopOperating andServiceWaterAvailable TypicalMin.'"ESWSafeShutdownFlow-2LoopsOperating andBothUnitsServiceWaterNotAvailable A(B)B(A)1)Standby'"
DieselGenerator HeatExchangers 4commontotal1210(A,B,C,D) 1254(E)'"
4840(4884)'"4840(4SS4)'"4840(4884)'"2)RHRPumpRoomUnitCoolers4003)RHRPumpMotorBearingOilCooler4)CoreSprayPumpRoomUnitCoolers1442414424144241445)HPCIPumpRoomUnitCoolers10202020206)RCICPumpRoomUnitCoolers10202020207)ControlStructure Chiller1commonperloop7407407408)Emergency Switchgear CoolingCondensing Unit7272729)RBCCWheatexchangeru'400 280010)TBCCWheatexchanger
"'4549011)MakeuptoFuelPools'"60120120TOTALLoopFlow(GPM)6380(6424)'"5448(5492)'"6380(6424)'"3898Rev.47,06/94 t~>.a.~-'
SSES-FSAR Page2of2TABLE9.2-3(Continued)
DEFINITION OFESWFLOWSFORUNITS1BE21)Ononelooponly.2)Valveinparenthesis iswithanythree(3)ofA,B,C5Dunitsinserviceinconjunction with"E"unit.3)TheDieselGenerator "E"flowrateshownonthistableisbasedonthecontinuous dutyratingofthedieselgenerator (5000kw)~4)BothloopsofESWarealignedtotheD/G's.Itispreferred thatonepumpperloopberunduringnormaloperations.
However,intheeventofaDBAandasinglefailureinESW,oneloopwillbeavailable tosupplythedesignflowtotheDieselGenerator.
5)Thiscolumnillustrates theESWsystemsabilitytosupplyDBAflowsinadditiontosupplying TBCCWandRBCCWwithbothloopsoperating.
Theactualflowratesineachloopwillvaryslightlybecauseofthecrosstieatthediesels(i.e.the"B"loopwillpasssomeflowtotheD/G's).I6)Themake-uprateshownhereisconservatively basedonanon-mechanistic boilingspentfuelpool(seeSubsection 9.1.3.1).
Theflowrateformake-upofevaporative lossesduringRHRFPCoperation wouldbesignificantly less.Rev.47,06/94 c>0)~~
SSES-FSAR whichisinthecontrolroom,andeachpumpchamberisprovidedwithalowlevelsubmergence switchwhichalarmsinthecontrolroom.9.2.5.6PieCrackLeakaeDetection LeakagefromtheESWScanbedetectedbyoneofseveralmethodsdepending onlocation.
LeakagefrompipingwithintheESSWPumphouse drainsintoapitwhichisequippedwithalevelswitchtoalarmonhighwater.Theyard.pipingfromtheESSWpumphouse tothepumpdischarge flowelementsiscontained inaguardpipewhichdrainsbacktotheESSWPumphouse andintothesamepitasdescribed above.Theremaining yardpipingislocatedinahightrafficareaandthepresenceofasignificant leakwillbevisuallyapparent.
Leakdetection withintheReactorBuildings, ControlStructure andDieselGenerator Buildings differsdepending onthelocation.
Seismically analyzedroomflooddetectors areusedinthelowestelevations, suchas,theRHR,CoreSpray,HPCI,RCICandTBCCWHeatExchanger rooms.Flooddetection fortheroomscontaining ESWlinessupplying theRBCCWheatexchangers, ControlStructure
- Chillers, Unit2DxunitsandFuelPoolMakeupisnotfeasiblenordesirable, sincethelinesarelocatedinupperelevations oftheReactorBuildingandControlStructure.
Intheseareas,floordrainsroutetheleakagetoradwasteviaeithertheReactorBuildingorTurbineBuildingsumps.Theexcessive influentintotheradwastesystemwillalertoperators toapipeleak.9.2.6RHRSERVICEWATERSYSTEM9.2.6.1DesinBasesTheResidualHeatRemovalServiceWaterSystem(RHRSWS)hasasafetyrelatedfunctionandisanengineered safeguard systemdesignedtosupplycoolingwatertotheresidualheatremoval(RHR)heatexchangers ofbothunits.TheRHRSWSisdesignedtotakewaterfromthespraypond(theultimateheatsink),pumpitthroughtheRHRheatexchanger,and returnittothespraypondbywayofaspraynetworkthatdissipates theheattotheatmosphere.
TheRHRSWSisdesignedtoprovideareliablesourceofcoolingwaterforalloperating modesoftheRHRsystemincluding heatremovalunderpost-accident conditions, RHRFuelPoolCooling(RHRFPC)following aseismicevent,andalsotoprovidewatertofloodthereactorcoreortheprimarycontainment afteranaccident, shoulditbenecessary.
Rev.47,06/949.2-19 I~(~SSES-FSAR 9.2.7ULTIMATEHEATSINKTheultimateheatsinkhassafetyrelatedfunctions andprovidescoolingwaterforuseintheEngineered Safeguard ServiceWatersystem,described inSubsections 9.2.5and9.2.6,duringESSWtesting,normalshutdown, andaccidentconditions.
9.2.7.1DesinBasesTheultimateheatsinkiscapableofproviding sufficient coolingwaterwithoutmakeuptothespraypondforatleast30daysto(a)permitsimultaneous safeshutdownandcooldownofbothnuclearreactorunitsandmaintaintheminasafeshutdowncondition, (b)mitigatetheeffectsofanaccidentinoneunit,permitsafecontrolandcooldownoftheotherunit,andmaintainitinasafeshutdowncondition or(c)permitsimultaneous safeshutdownandcooldownofbothunitsandmaintaintheminsafeshutdownwhileproviding adequatecoolingtobothspentfuelpoolsfollowing aseismicevent.Continued coolingbeyond30daysisensuredbyuseofthemakeuppumpstokeepthepondatnormalwaterlevel.ThemakeuppumpsaredesignedtooperatebelowthehistoricminimumwaterleveloftheSusquehanna River.Intheeventthatmakeupwaterfromthemakeuppumpsisnotavailable, additional provisions willbemadeinthe30daysavailable toassurecontinued coolingoftheemergency equipment beyond30days.Theseprovisions includebutarenotlimitedto:re-establishing makeuppumpflowtothespraypond,emptyingthecoolingtowerbasinsintothespraypond,truckinginwaterfromneighboring watersources(suchastheSusquehanna River),andproviding temporary pumpsand/orlinestopumpwaterfromneighboring watersources(suchastheSusquehanna River,onsitestoragetanks,wellwater,etc.)'.Thisisincompliance withNRCRegulatory Guide1.27Rev.2asdiscussed inSection3.13.Theultimateheatsinkisalsocapableofproviding enoughcoolingwaterwithoutmakeup,foradesignbasisLOCAinoneunitwiththesimultaneous shutdownoftheotherunit,for30dayswhileassumingaconcurrent SSE,singlefailure,and.lossofoffsitepower.Thiseventisevaluated inSubsection 9.2.7.3.1.
Theultimateheatsinkconsistsofatleastonehighlyreliablewatersourcewithacapability toperformthesafetyfunctionrequiredaboveduringandafteranyoneofthefollowing postulated designbasisevents:a)Themostseverenaturalphenomena, including thesafeshutdownearthquake, tornado,flood,ordroughttakenindividually Rev.47,06/949.2-25
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SSES-FSAR Page1of1TABLE9.2-8SUSQUEHANNA PONDWATERALLOWANCES LossDescription WaterAllowance (x10'al)a)Evaporation duetoheatdissipation dutyformaximumwaterlosscase7.95b)Driftfromwindformaximumwaterlosscase1.15c)Percolation throughthepondlining0.3d)SystemchargingvolumeNegligible e)Maximumsolarevaporation losses1.85f)Lossesresulting fromwaveactionul0g)Lossesresulting fromsedimentation'"
1.0h)Fuelpoolmakeup'"5.0i)Acontingency forwaterqualityconsiderations 2.7TotalPondVolumeRequired19.95TotalPondVolumeProvided25.0Basedondesignprovisions forprotection fromthisloss.(2)Negligible sedimentation isanticipated.
Thevaluegivencorresponds to6in.ofponddepth,whichisaconservative allowance betweencleaningperiods.(3)Foradditional conservatism, thisvalueassumesboilingofthefuelpoolsconsistent withthenon-mechanistic boilingpoolanalysisinAppendix9A.Rev.35,07/84 SSES-FSAR APPENDIX9AANALYSISFORNONSEISMICSPENTFUELPOOLCOOLINGSYSTEMSAsdescribed inSubsection 9.1.3theSpentFuelPool(SFP)CoolingSystemsaredesignedasnon-sei'smic CategoryI,QualityGroupCsystems.Consequently, theradiological consequences ofalossofspentfuelpoolcoolingduetoaseismiceventareevaluated.
Inordertoperformthisanalysisitisnecessary toassumetheSFPwillboileventhoughSection9.1.3.3establishes thatthedesignbasisoftheplantforthiseventistopreventboilingthroughtheuseoftheRHRFPCmode.Sincethecoolingsystemsforbothunitsarecross-connected andincloseproximity itwasassumedthataseismiceventcausesthelossofcoolingtobothspentfuelpools.Inaddition, inordertomaximizeboth'heheatloadsandtheiodineinventories inthepools,refuelings within135dayswerepostulated.
(Periodoftimebetweenoutagesisnominally 180days,thususeof135daysisconservative.)
Thelossofcoolingwasassumedduringthesecondrefueling, justafterisolation ofthepools(i.e.,refueling andcaskpitgatesinstalled).
TheRHRsystemisassumedtonotbeavailable forcoolingtheSFPeventhoughitwouldbeabletoprovidecoolinginresponsetothisevent.Thus,itisassumedthatthepoolswillboil.Theanalysisinvolvedanevaluation ofthetimetopoolboiling,theabilitytomaintainwaterlevelifthepoolboils,andthethyroiddoseconsequences attheLPZboundaryduetoiodinereleasesfromtheboilingpools.Theassumptions usedinthisanalysiswereconsistently chosentobeconservative andboundingsimilartothoseinRegulatory Guidesfordesignbasisaccidents (e.g.,Regulatory Guides1.3,1.25,etc.).Thecombination ofallofthesedesignbasisassumptions occurring atthesametimewouldbeextremely
- unlikely, makingthisaccidentasanalyzed, oneofverylowprobability.
Manyoftheassumptions areconsidered tobeoverlyconservative.
Forexample,operating experience withpresentBWRfuels(Reference 9A-1)indicates thattheassumption of700pCi/sec(fullpowerdesignbasisleakagerate)isconservative fordetermining reactorcoolantconcentrations duringoperating conditions.
ThissameleakageratewillbeassumedforthefuelintheSFP,whichisevenmoreconservative.
Eventhoughspikingfactorshaveyettobeobservedforatemperature riseinSFPs,spikingfactorshavebeenutilized.
Amorerealistic evaluation ofthisaccidentwouldresultinreleasesofradioactivity, ifany,manyordersofmagnitude belowthecalculated values.Therealistic releaseswouldbewellbelowthe10CFR50AppendixIrelatedTechnical Specifications, indicating thatsuchanincidentisoflittleornoconsequence.
Rev.46,06/939A-1 SSES-FSAR Thepoolswillbeoperatedinamannerwhichwillensurethattheywillnotboiluntilatleast25hoursafterthelossofcooling.Sincecoolingisassumednottoberestoredbeforethepoolboils,makeupwaterfromtheCategoryIEmergency ServiceWaterSystemisassumedtobeaddedtothepoolatarateequaltotheboilofftokeepthefuelcoveredwith23feetofwateratalltimes.AsshowninTable9A-1,thethyroiddoseconsequences oftheboilingpool,withoutoperation oftheStandbyGasTreatment System,arewellbelowtheguideline valuesof10CFR100andthe1.5REMthyroidguideline ofRegulatory Guide1.29.Thefollowing assumptions wereusedtocalculate theheatgeneration andboilingrate.l.Eachfuelpoolisfullwith2850fuelassemblies.
Themaximumexpecteddischarge batchsizeof280assemblies wasusedforthemostrecentoffloadineachpool.Theearlieroffloadswerebasedon256assemblybatchsizes.Todetermine theheatloadandthusboilingevaporation rate,sequential refuelings 129daysapartareassumed.Theeventisassumedtooccur6daysafterthesecondunitis,shutdown.
Sixdaysisconservatively chosenastheminimumtimetounload280assemblies andreinstall thefuelpoolgates(thusisolating thepool).Therefore, oneunit'sfuelpoolinventory isassumedtohavedecayedfor6days.Actualsequential refuelings occurapproximately 180daysapart.Thenormaltimetodefuel280assemblies is8days.Theseassumptions maximizetheheatloadintherecentlydefueledpoolandthustheboilingevaporation rate.Theanalyseswereperformed forpoweruprateconditions.
2.Thedecayheatwascalculated usingtheANSI/ANS-5.1-1979 decayheatstandard.
Thisstandardincludesmethodology forcalculating thedecayuncertainty.
Allvaluesofthedecayheatinthissectionareequaltothenominalvalueplustwostandarddeviations.
3.Todetermine aconservative boilingevaporation rateforpurposesofthisradiological evaluation, allheatgenerated bythefuelisassumedtobeabsorbedbythewaterinordertominimizethetimetoboiling.Noheatislosttothesurroundings byconduction throughtheconcreteandsteel,orbyevaporation.
Thetemperature gradients fromthefuelatthebottomofthepooltothecoolerwateratthetopwillcreateconvective waterandheatcurrentswhichwillthoroughly mixthewater,andpromoteanevendistribution ofheatratherthanlocalized pointsofsurfaceboiling.Rev.46,06/939A-2 SSES-FSAR 4.Theactivityreleaseratefromthepooldependsontheevaporation rateandtheiodinecarryover fractionatthepoolsurface.Theevaporation ratepriortoboilingisboundedbytheevaporation rateatinitiation ofboiling.Itisconservatively assumedthattheevaporation ratepriortoboilingisthesameasthatduringboiling.Rev.46,06/93 rQl0$~'l'.'