MAAP4.0.6 Simulation of Beyond DBA BWR3 Mark I rev03
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This document summarizes a simulation of beyond design basis accident (BDBA) scenarios for a BWR3 Mark I nuclear power plant. It describes the plant's safety features for design basis accidents as well as additional beyond DBA features like manual depressurization and alternate water injection sources. It then simulates the progression of a loss of feedwater accident where high and reactor core isolation cooling fail, including a discussion of venting strategies and the potential for containment failure and radioactive release. Emergency water makeup capabilities are also evaluated.
MAAP4.0.6 Simulation of Beyond DBA BWR3 Mark I rev03
- 1. MAAP4.0.6SimulationofBeyondDBA MAAP4 0 6 Simulation of Beyond DBA BWR3MarkI Dr.JohnH.Bickel
- 2. MonticelloNuclearGeneratingPlant,Monticello,Minnesota 1775MWt (currently)2004MWt (EPU)XcelEnergy OriginalLicense:91970ReLicensedtooperateuntil2030 Original License: 9 1970 Re Licensed to operate until 2030 2
- 3. BWR3,MarkI DBAFeatures: ElectricdrivenMainFeedwater,CondensatePumps 2Dieselssupply:4kVpower,480V,250VDC,125VDC 2 Trains Electric Driven LPCI with 2 RHR Heat Exchangers 2TrainsElectricDrivenLPCIwith2RHRHeatExchangers SafetysystemdesignedforLargeDesignBasesLOCA LPCIalsohasDrywellandSuppressionPoolSprayFunction 2TrainsElectricDrivenCoreSprayPumps SafetysystemdesignedforLargeDesignBasesLOCA 1 Train HPCI with suction from CST 1TrainHPCIwithsuctionfromCST SafetysystemdesignedforSmall/MediumLOCA AutomaticDepressurizationSystem S f SafetysystemdesignedforSmall/MediumLOCAwithHPCIfailure d i d f S ll/M di LOCA i h HPCI f il 1TrainRCICwithsuctionfromCST NonSafetysystemdesignedforheatremovalwhenmaincondenser unavailable 2TrainsHPControlRodDriveHydraulicPumps(~90200gpm) 3
- 4. BWR3,MarkI BeyondDBAFeatures: BWR3, Mark I Beyond DBA Features: 2trainsManualSLCScapableofinjectingSodiumPentaborate AnticipatedTransientsWithoutScram CSTcanbereplenishedwithRiverwaterorFireTrucktoprolong HPCI,RCIC,CRDinjection HPCI, RCIC, CRD injection SecurityDiesel480VpowercanbeconnectedtoBattery Chargers(prestagedcablespoolswithquickconnectplugs) AlternateMakeuptoReactorviaexistingpipingconnections: RHRServiceWater(fromRiver) Diesel Driven Fire Pump (from River) DieselDrivenFirePump(fromRiver) B.5.bPump(fromRiver) 18HardPipeVentfromTorustoAtmosphere(preferred) 18equivalentto~21MWt decayheatremoval(~decayheatafter1hr) 4
- 5. 京安檎3油敬庄岳鞄油珂温姻一油鴛油遺看稼岳温庄稼馨艶稼岳 (CourtesyofGeneralElectric) Features: Engineeredin1960sto addressLargeDBALOCA DesignPress:56psig UltimatePress.~110psig Hard Pipe Vent installed to HardPipeVentinstalledto ventTorustoatmosphere Limitations: Small,compact,containment volumerequiresN2 inerting for DBALOCA Credits DBA Large LOCA CreditsDBALargeLOCA containmentpressuretoassure ECCSpumpNPSH Notdesignedforsevere accidents id 5
- 6. 珂温姻一油鴛油遺看稼岳温庄稼馨艶稼岳油雨稼糸艶姻油遺看稼壊岳姻顎界岳庄看稼 CourtesyTVABrownsFerryNPP 6
- 7. 安鞄温岳油檎艶温界岳看姻油京顎庄鉛糸庄稼乙油晦看看一壊油晦庄一艶油庄稼油檎艶韓顎艶鉛庄稼乙油敬庄岳鞄 DrywellHeadRemoved CourtesyTVABrownsFerryNPP 7
- 8. 安鞄温岳油檎艶温界岳看姻油京顎庄鉛糸庄稼乙油晦看看一壊油晦庄一艶油禽顎姻庄稼乙油或沿艶姻温岳庄看稼油 CourtesyTVABrownsFerryNPP 8
- 9. 8油皆温韓艶岳霞/檎艶鉛庄艶韓油閣温鉛厩艶壊油(皆/檎閣壊) Features: DualAction Mechanicalspringloaded overpressuresafetyfunction f t f ti DC/N2 operatedreliefvalve function(forautomatic depressurization) 3/8S/RVsusedtorapidly depressurizeRPVtoallowcore flooding. Limitations: PhysicallylocatedinDrywell OnlossofDC,orPress>75psig: reliefmodeisinoperable Electropneumaticcontroller canfail ifDrywellTemp.>335F (currentQualificationTemp.) (current Qualification Temp ) MonticelloNGP 9
- 10. S/RVControlsfor EmergencyManualDepressurization Emergency Manual Depressurization MonticelloNGP 10
- 11. 堰庄乙鞄油永姻艶壊壊顎姻艶油遺看看鉛温稼岳油鴛稼逮艶界岳庄看稼油皆霞壊岳艶馨: Features: Caninjectatfullsystem press.(1050psia) ~1 5x106 lbs/hr makeup 1.5x10 lbs/hrmakeup capability CSTiswatersource,Torusis alternatewatersource Designedtomitigatesmall, mediumLOCA Canbestartedlocally,run withoutDCpower without DC power Limitations: NeedsRPVsupplypress.> 50psig 50 i Needsexhaust(Torus) press.<75psig p DCpowerneededtoremote start WhenTorususedaswater 11/29/2011 11 source,Temperature<200F
- 13. 堰庄乙鞄油永姻艶壊壊顎姻艶油檎遺鴛遺油皆霞壊岳艶馨油: Features: Can inject at full system Caninjectatfullsystem press.(1050psia) ~2x105 lbs/hrmakeup capability(smallerthanHPCI) Designedtoprovidemakeup aftershutdownwhenFW unavailable CSTiswatersource,Torusis CST is water source Torus is alternatewatersource Canbestartedlocally,run withoutDCpower Limitations: NeedsRPVsupplypress.> 50psig Needsexhaust(Torus) press.<75psig DCpowerneededtoremote start t t WhenTorususedaswater source,Temperature<200F 13
- 14. 檎遺鴛遺油鴛稼糸庄界温岳庄看稼壊油看稼油遺看稼岳姻看鉛油京看温姻糸 MonticelloNGP 14
- 15. 安鞄温岳油檎遺鴛遺油意顎姻恢庄稼艶油禽姻庄厩艶稼油永顎馨沿油晦看看一壊油晦庄一艶 CourtesyTVABrownsFerryNPP 15
- 16. 掘恰温馨沿鉛艶油看韓油永姻艶S岳温乙艶糸油掘援顎庄沿馨艶稼岳油韓看姻油 BeyondDesignBasesAccidents Beyond Design Bases Accidents MonticelloNGP 16
- 17. 皆岳温岳庄看稼油禽遺油京温岳岳艶姻庄艶壊 Features: 2x250VBatteries 2x125VBatteries TypicalLeadAcid storagecells Limitations: 250VBatteriesdeplete in78hrswithout charging 125VBatteriesdeplete in5.55.75hrswithout charging Depletiondefinedas insufficientvoltageto operatecriticalSOVs CourtesyTVABrownsFerryNPP C t TVA B F NPP 17
- 18. ContainmentVentfor BeyondDesignBasesAccidents d d MainFeatures: SuppressionPoolVent Redundantairoperated butterflyvalves(fail butterfly valves (fail closedonlossofair) >56psigrupturediskto preventoperation belownormaldesign basespressures RequiresDCpower, compressedairto operate p 18
- 19. 遺看稼岳姻看鉛油檎看看馨油晦温霞看顎岳 MonticelloNGP 19
- 20. LossofFeedwaterwithnoHeatRemoval InitiallymoreseverethanLossofOffsitePower Reactortrip,MSIVclosureisDelayed Rate of initial RPV Level Drop is Faster RateofinitialRPVLevelDropisFaster SteamDrivenhighpressuremakeupsources(HPCI, RCIC)notConsidered RCIC) not Considered yet CRDHydraulicmakeupnotconsidered yet AC/DC power available compressed N2 available AC/DCpower available,compressedN available OperatorsfollowEOPsanddepressurizeatTAF reflooding with LPCI to achieve stable water levels withLPCItoachievestablewaterlevels SuppressionPoolCoolingfailsoverlongterm Drywell Chillers Containment Venting not considered DrywellChillers,ContainmentVentingnotconsidered ThisisadominantPRAaccidentsequence 20
- 22. 掘恰艶界顎岳庄稼乙油掘馨艶姻乙艶稼界霞油禽艶沿姻艶壊壊顎姻庄噛温岳庄看稼油敬庄岳鞄油晦永遺鴛油看姻油遺看姻艶油 SprayRefloodat126 is well practiced procedure Spray Reflood at 126iswellpracticedprocedure 22
- 23. 檎永閣油晦艶厩艶鉛油鴛稼糸庄界温岳看姻油看稼油遺看稼岳姻看鉛油京看温姻糸 MonticelloNGP 23
- 24. EmergencyDepressurizationallows LowPressureCoolantInjectiontorefloodcore L P C l I j i fl d 24
- 25. AtthispointRPVlevelisrestoredandcore coolingusinginjectedLPCIflowfromTorus cooling using injected LPCI flow from Torus 25
- 26. WithoutAnySuppressionPoolCooling: ContainmentTemperatures,Pressurescontinuallyrise Containment Temperatures Pressures continually rise 26
- 27. 檎艶界鉛看壊顎姻艶油看韓油皆/檎閣壊油簡21.5鞄姻壊:油界温顎壊艶壊油檎永閣油沿姻艶壊壊.油姻庄壊艶油 p p p aboveLPCIpumpshutoffpressure 27
- 28. 鴛韓油意看姻顎壊油界看看鉛庄稼乙油韓温庄鉛壊,油掘或永壊油界顎姻姻艶稼岳鉛霞油糸庄姻艶界岳油 ventingwhenpressure>56psig: venting when pressure >56psig: 28
- 29. 鴛韓油厩艶稼岳庄稼乙油韓温庄鉛壊:油遺看姻艶油雨稼界看厩艶姻霞油簡29鞄姻壊油敬鞄庄鉛艶油沿姻艶壊壊顎姻艶油 remainselevatedatS/RVsafetyvalvepress. remains elevated at S/RV safety valve press 29
- 30. 禽艶鉛温霞艶糸油遺看姻艶油堰艶温岳顎沿油壊岳温姻岳壊油温岳油簡29.5鞄姻壊油敬庄岳鞄 ZrWaterReactionstarting~30.5hrs Z W R i i 30 5h 30
- 32. 遺看稼壊艶援顎艶稼界艶壊油敬看顎鉛糸油恢艶油晦温姻乙艶油禽艶鉛温霞艶糸油檎艶鉛艶温壊艶 ( (~30%CoreCsI)afterContainmentFailure ) Note:Degreeofretentionoffissionproductswithinreactorbuildingnotmodeled. 32
- 33. MitigationStrategy: MitigationStrategy:Ifunabletovent,howmuch watermakeupneededtocoolcore? water makeup needed to cool core? Matchboiloffduetodecayheat: WBOIL =QDECAY(26hrs)/h QDECAY(26hrs)=3.88x107 BTU/hr h=hsat(1050psia) hCST(80F)~1142.3BTU/lbm WBOIL =(3.88x107 BTU/hr)/(1142.3BTU/lbm)=34,000lbm/hr or:=(567lbm/min)(0.016ft3/lbm)=9.07ft3/min Convertingtogal/min,thisisonly:~67.8gpm 67.8gpm Recall:CRDmakeupflowtoRPVis:90 200gpm 90 200gpm 1electricCRDpumpcouldeasilykeepthecorecoveredforan indefiniteperiodoftimeifcontainmentoverpressurefailuredoes i d fi it i d f ti ifcontainmentoverpressurefailuredoes if t i t f il d notimpactCRDpumpoperatingenvironment. 33
- 34. EvaluationofStationACBlackout Lossofoffsitepowercauses:LossofFeedwater.Lossof RecirculationFlow,MSIVclosure,ReactorTrip,Recirc.PumpSeal Leakage(37 165gpm)likely g ( gp ) y Dieselsfail,DCBatteriesbegintodischarge AllACpoweredequipmentshutsdown F d t Feedwaterandcondensatepumps d d t DrywellCoolers,roomcooling LPCI,CoreSpray,CRDpumpscannotbeoperated HPCI RCIC potentially available provided RPV steam and DC HPCI,RCICpotentiallyavailableprovidedRPVsteamandDC availableforstarting,anduntilroomtemperatures>150F CSTavailableaswatersource S/ V S/RVspotentiallyavailabletoblowdownifcontainmentpressure i ll il bl bl d if i <75psig,and BOTH:DCpower,compressedN2 available DieselFirePump(portablepumps)potentiallyavailableuntilout offuel 34
- 35. HPCI/RCICstartonlowlevel.RCICthrottled SuctionfromCST,andrunonlocal/manualwithoutDCpower , / p Notes: (1) RunningHPCI onecyclerapidly l idl refillsRPV causingHPCI, RCICauto shutdown. (2)Runningwith HPCIinpullto lockandRCIC lock and RCIC throttled minimizeson/off cycles andthus conservesDC batteries. 35
- 36. RCICwillshutdownwhenSuppressionPool Pressureexceeds64.7psiaat 13 9 hrs Pressure exceeds 64 7psia at ~13.9hrs. 36
- 37. 遺看姻艶油雨稼界看厩艶姻霞:油簡15.5油鞄姻壊,油遺看姻艶油珂艶鉛岳:油簡17油鞄姻壊 RPV Pressure (psia) vs. Level (ft) 3 1.210 3 1.110 3 110 40 900 800 ressure (psia) 30 XWCORE RP Level (ft) 700 XWSH PPS 600 TAF PV BAF Pr 500 20 400 300 10 200 100 0 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 time Time in Hours 37
- 38. 遺看稼岳温庄稼馨艶稼岳油或厩艶姻沿姻艶壊壊顎姻艶油酷温庄鉛顎姻艶:油簡20.4油鞄姻壊 Issues: (1)EOPC.51200 callsforventing calls for venting containmentat 56psig(70.7psia) At~15hrs. (2)Without charging,last batteryisdepleted depleted ~8hrs. 8hrs 38
- 39. SRVsPossiblyCouldnotbeoperated>8hrs dueto335 Fequipmentqualificationuncertainties due to 335F equipment qualification uncertainties Drywell, Suppression Pool Temp (F) 3 110 900 800 700 Pressure (psia) PoolTemp 600 DWTemp SRVLimTemp 500 ContFailTemp 400 300 200 100 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 TIME 39 Time in Hours
- 40. EOPC.51200DirectsOperatorstomaintainTorus TemperaturewithinHeatCapacityTemperatureLimit Temperature within Heat Capacity Temperature Limit byControlledRPVDepressurization 11/29/2011 jhbickel@esrtllc.com 40
- 41. Whatislearnedfromallthis: Ifthereisnocontainmentheatremovalworking,highpressuresteam drivenpumpswilleventuallyshutdownonbackpressureat~13.9hrs B tt i ( ith t h Batteries(withoutchargers)willallbedepletedby~78hrsand ) ill ll b d l t d b ~7 8h d unavailabletoopenS/RVsorcontainmentventvalves. Drywelltemperatures>335FchallengeEQlimitforS/RVoperationat ~8hrs Containmentpressurereaches>56psigforproceduralcontainment ventingat 15hrsbutthisis7hrs venting at ~15hrs but this is 7hrs after battery depletion 7hrsafter batterydepletion VentingatthistimecouldallowlocalmanualrestartingofRCICpumpin timetorecoverwaterlevelbutthereisnoDCpower butthereisnoDCpower M i i i MaintainingcorecoolingisthusdependentonDCpower li i h d d DC InStationACBlackout:containmentventingneedstobeconsideredearlier topreservecorecoolingoptions. to preserve core cooling options 41
- 42. Usingtheseinsights: Simulationstudiesthenperformedonhowtosuccessfullycope withprolongedSBObutalso:SeismicSBO p g Inbothcases:nopossibilityforTorusCooling nopossibilityforTorusCooling SeismicSBOdiffersfromSBO: Offsitepowerrecoverymayrequireweeks vs.hours PossiblydestroysCST(requiringHPCI,RCICsuctionfromTorus) ThiscausesmorerapidTorusHeatup p p PossiblydestroysDieselFireWatermakeup(buriedpiping,castironpiping inbuildings) Successful coping depends on: Successfulcopingdependson: GasolinepoweredportableDCbatterychargers(orSecurityDiesel) Portable,Gasolinepoweredpumps Aircompressororbottledgassupply 42
- 43. Strategy:BreakRuptureDiskbelow56psig usingbottledgascylinderandtestconnection using bottled gas cylinder and test connection Availabilityofcompressedair compressedair andDC becomesessentialto DC maintainContainmentVent Pathopenforheatremoval. 43
- 44. VentContainment,butkeeppressure:15 25psig ( (IfanyhydrogenwerepresentincontainmentitwouldbeinertedviaexcessNitrogenandlacking y y g p g g sufficientOxygentoignite.Thus:wedontwantoutsideatmosphericairenteringcontainment sokeep pressurized) 44
- 45. InitiateManualDepressurizationwhen SuppressionPoolheatsup(asincurrentEOPs) Suppression Pool heats up (as in current EOPs) 45
- 46. Afterdepressurizationat~8hrscorecoolingcanbe providedbylowpress.100gpmportablepump provided by low press 100gpm portable pump 46
- 47. Whatislearnedfromallthis: CurrentguidancetouseHPCIonceandthrottledRCIC:works works Alternate means will be needed for DC Battery charging ~5hrs AlternatemeanswillbeneededforDCBatterycharging 5hrs VentingContainmentisneededearlier(~8hrs) VentingContainmentisneededearlier(~8hrs)tomaintainlower DrywellTemperaturestooperateS/RVsallowingemergencyRPV depressurization Earlierventingrequiresdefeating56psigrupturedisk EmergencyRPVdepressurizationascurrentlyinEOPswillallow d i i l i ill ll useofsmallerportablepumps Successfully executing this long term coping strategy requires Successfullyexecutingthislongtermcopingstrategyrequires logistics ofstagedequipment andsupplyofconsumables(fuel stagedequipment fuel, compressedgas) compressedgas 47
- 48. Supplemental Supplemental 48
- 49. 堰看敬油晦看稼乙油遺温稼油鰻永永油遺看沿艶油 WithoutDecayHeatRemoval? Without Decay Heat Removal? Coping time is: time from when heat removal is lost to Copingtimeis:timefromwhenheatremovalislostto onsetofseverecoredamage(availablerecoverytime) Copingtimeconsiders: Coping time considers Physicalinertiabuiltintoreactordesignviawaterto waterto corepowerratio Effects of water makeup systems Effectsofwatermakeupsystems Effectsofsupportfeatures(DCpower,HVAC)which enablewatermakeupsystems enable water makeup systems 49
- 50. 皆庄馨沿鉛庄韓庄艶糸油禽艶界温霞油堰艶温岳油珂看糸艶鉛: 50
- 51. BehaviorofRPVLevelwithRCIC: Assumepressure~1050psia ,constantduetoreliefvalveoperation Atconstantpressurewatermasslossisrelatedtodecayheat,thus: WLOSS(t) =QDECAY(t) / hfg =0.15Qot0.286 / hfg (t) Q (t)/h 0.15Q /hfg(hfg =640BTU/lbm.) 640 BTU/lbm.) Assumecoreoutputinitiallyat:Qo~6.84x109 BTU/hr Assumewhenactivated:RCICinjects:WRCIC(t)~2.0x105 lbm./hr. Assumeinitialwatermassabovecore:MCORE~1.2x105 lbm. Behaviorofwaterinventorygovernedby: dM CORE WRCIC WLOSS dt 0.15Qot 0.286 t M CORE (t ) M CORE (0) (WRCIC )dt 0 h fg 0.15Qo 0.714 M CORE (0) WRCIC t t (0.714)h fg 51
- 53. BehaviorofWaterafter RCICstops: AssumeRCICcannotbeoperatedafter8hrs Pressure~1050psia andconstantduetoreliefvalveoperation Atconstantpressurewatermasslossstillrelatedtodecayheat At constant pressure water mass loss still related to decay heat Ifcoreoutputinitiallyat:Qo~8.13E+9BTU/hr WhenRCICstops:WRCIC(t)~0.0lbm./hr. Assumesameinitialwatermassabovecore:MCORE~1.2E+5lbm. Behaviorofwaterinventorygovernedby: dM CORE WLOSS dt 0.15Qot 0.286 t M CORE (t ) M CORE (8hrs ) ( )dt 8 h fg 0.15Qo 0.714 M CORE (8hrs ) (t 8hrs 0.714 ) 0.714h fg 53
- 54. 京艶鞄温厩庄看姻油看韓油安温岳艶姻油温韓岳艶姻油檎遺鴛遺油壊岳看沿壊: Slowsteadyboiloffdictatedbydecayheatcurve l d b l ff d db d h 54
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