核反应堆工程核反应堆工程 (9).ppt
Nuclear Reactor EngineeringIntroduction of Generation IVAdvanced ReactorOverview1BackgroundofGenerationIVAdvancedReactorDescriptionsofGenerationIVAdvancedReactor3SummaryofGenerationIVAdvancedReactor2BackgroundNuclearpowerplantdevelopmentnGenI(1950-1970):TheearlyprototypereactorsnGenII(1970-1990):CommercialpowerplantsthatarestilloperatingtodaynGenIII/III+(1990-2030):OffersignificantadvancesinsafetyandeconomicsnGenIV(2030):SignificantlydifferentfromGenIII/III+,belongstothenuclearpowerrevolutionnIn2001,theUnitedStatesledtheestablishmentofGIF,whichaimstoresearchanddevelopthefourthgenerationnuclearenergysystem,andisexpectedtobeputintouseby2030.nMembers:US,China,UK,France,Canada,Japan,SouthKorea,Brazil,Argentina,etc.Generation IV International Forum,GIFBackgroundnSustainability1:Providesustainableenergygenerationthatmeetscleanairobjectivesandpromoteslong-termavailabilityofsystemsandeffectivefuelutilizationforworldwideenergyproduction.nSustainability2:Minimizeandmanagetheirnuclearwasteandnotablyreducethelong-termstewardshipburden,therebyimprovingprotectionforthepublichealthandtheenvironment.nEconomics1:Haveaclearlife-cyclecostadvantageoverotherenergysources.nEconomics2:Havealeveloffinancialriskcomparabletootherenergyprojects.BackgroundGoalsforGenerationIVNuclearEnergySystemsnSafety and Reliability1:GenerationIVnuclearenergysystemsoperationswillexcelinsafetyandreliability.nSafety and Reliability2:Haveaverylowlikelihoodanddegreeofreactorcoredamage.nSafety and Reliability3:GenerationIVnuclearenergysystemswilleliminatetheneedforoffsiteemergencyresponse.nProliferationResistanceandPhysicalProtection1:Increasetheassurancethattheyareaveryunattractiveandtheleastdesirableroutefordiversionortheftofweapons-usablematerials,andprovideincreasedphysicalprotectionagainstactsofterrorism.BackgroundGoalsforGenerationIVNuclearEnergySystemsOverview1BackgroundofGenerationIVAdvancedReactorDescriptionsofGenerationIVAdvancedReactor3SummaryofGenerationIVAdvancedReactor2VHTR（Thermal）SFR（Fast）MSR（Thermal/Fast）SCWR（Thermal/fast）GFR（Fast）LFR（Fast）OverviewVery-High-Temperature Reactor(VHTR)ParametersValueAveragepowerdensity610MWt/m3Coreoutlettemperature900ElectricpowerconversionDirect/indirectBraytoncycleNetplantefficiency45%nTheVHTRisagraphite-moderated,heliumcooledreactorwiththermalneutronspectrum.nGraphitealsoservesasastructuralmaterialforthecore.General DesignnTheVHTRisthenextgenerationinthedevelopmentofhigh-temperaturereactors and is primarily dedicated to the cogeneration of electricity,hydrogen,andprocessheatforindustry.nThereactorcoretypeoftheVHTRcanbeaprismatic block coresuchastheoperatingHTTR,orapebble-bedcoresuchastheChineseHTR-10.nThecoreofaVHTRhasapowerdensityintherangeof4to10MW/m3.Theheatoutputgenerallytargetedbydesignersisbetween250and600MWforathermodynamicefficiencyofaround45%.LiketheHTR,theVHTRisamodulardesign.Very-High-Temperature Reactor(VHTR)General Safety OptionsnThemainobjectiveinthedesignofaVHTRistopreventanyaccidentsthat may occur at the facility from leading to significant releases ofradioactivity.Mainsafetyoptionsas:nDesigningthecore(size,powerdensity,built-inreactivity)sothatthefuelcladdingandthestabilityofthecorestructuresareprotectedduringallaccidenttransientsusedforthesafetydemonstration;nDeterminingneutronfeedbackcoefficientsthatreducethereactorpowerintheeventoflossofcooling(lossofheatsinkordepressurization)withouthavingtotriggeranemergencyshutdown;Very-High-Temperature Reactor(VHTR)General Safety OptionsnCooling of the reactor pit and the vessel(second barrier)by anexternalcircuitabletooperateinnaturalconvectionmode(especiallyincaseoflossofelectricalpowersupply);nContinuous high-efficiency purification and monitoring of primaryheliumactivitylevels;nInthecaseofasecondarywater/steamcircuit:limiting,bydesign,theamountofwaterthatcouldbeinjectedintothecoreintheeventofanaccident and mitigating the induced reactivity insertion(coreoptimization).Very-High-Temperature Reactor(VHTR)VHTR Achievement of Generation IV Goals nSustainability Notintendedtoaddresssustainabilitygoalsforutilizingaoncethroughopenfuelcycle.nEconomics Highratingfortheeconomicgoalsforitscapabilitytoproduceelectricityathigh power conversion efficiencies and provide high-temperature thermalenergyforheatapplicationssuchastheproductionofhydrogen.nSafety and Reliability Highratingforsafetygoalsbecauseofinherentlysafedesignfeatures.nProliferation Resistance and Physical Protection Thegeneraldesignofthereactoranditsflexiblefuelcycleaddressesthegoal.Very-High-Temperature Reactor(VHTR)Summary of VHTR projectsVHTR（Thermal）SFR（Fast）MSR（Thermal/Fast）SCWR（Thermal/fast）GFR（Fast）LFR（Fast）OverviewParametersValueAveragepowerdensityAbout22MWth/m3CoolantMoltenfluoridesaltsModeratorGraphiteVaporpressure0.1psiCoreoutlettemperature700-850PowerCycleMulti-reheatrecuperativeheliumBraytoncycleNetthermalefficiency44to50%Molten Salt Reactor System(MSR)nTheMSRproducesfissionpowerinacirculatingmoltensaltfuelmixture.nReactorsthatuseasolidfuelandamoltensaltcoolantUnique characteristicsnMSRs have good neutron economy,opening alternatives for actinideburningand/orhighconversionnMoltenfluoridesaltshaveaverylowvaporpressure,reducingstressesonthevesselandpipingnRefueling,processing,and fission product removal can be performedonline,potentiallyyieldinghighavailabilitynConceptualdesignactivitiesarecurrentlyunderwaysoastoascertainwhetherMoltenSaltFastReactor(MSFR)systemscansatisfythegoalsofGenerationIVreactorsMolten Salt Reactor System(MSR)General Safety OptionsnDevelopmaterialsresistanttohightemperatures,irradiation,erosionandcorrosioncausedbysalts;nDefinethegeometriccharacteristicsofthefuelsystemwithaviewtocontrolling salt reactivity,taking into consideration the intendedoperatingtemperaturesandthechangesinfuelsaltcompositionoverthecourse of the operating cycle(which requires the strong relationshipbetweenthenuclear,thermal-hydraulicandthermochemicalaspectstobetakenintoaccount);Molten Salt Reactor System(MSR)General Safety OptionsnDesignafuelsaltemergencydrainingsystemtoenabledecayheatremovalfromthefuelduringoutagesandinaccidentconditions,andtokeepthesaltsubcritical;nAdopt measures to maintain the salt temperature above itssolidificationpointinallforeseeableconditions;nDefineaconfinementstrategywithappropriateconsiderationforthechemicaltoxicityofthesaltsusedandtheproductsgeneratedduringreactoroperationandinthetreatmentunit.Molten Salt Reactor System(MSR)MSR Achievement of Generation IV Goals nSustainability Becausetheconceptofclosedfuelcycleandactinidesandothernuclearfuelbyproductscanbeburnedbyaddingtheseconstituentstothecirculatingliquidfuelinacontrolledfashion,butwithoutspecialfuelfabricationneeds.nEconomics UnclearUnclear because of the early stage of development of the design,and theanticipated large number of subsystems and component required fordevelopmentofaviabledesignconcept.nSafety and Reliability and Proliferation Resistance and Physical Protection UncertainBothwillbeaddressedinthedesignapproaches,butremainuncertainbecauseoftherelativeimmaturityofthisspecificdesignconcept.Summary of MSR projectsMolten Salt Reactor System(MSR)VHTR（Thermal）SFR（Fast）MSR（Thermal/Fast）SCWR（Thermal/fast）GFR（Fast）LFR（Fast）OverviewSupercritical Water-Cooled Reactor(SCWR)ParametersValueAveragepowerdensityAbout100MWth/m3CoolantLight/heavywaterModeratorNo/heavywaterCoolantpressureAbout25MPaCoreoutletpressureAbout510ElectricpowerconversionBraytoncycleNetplantefficiencyAbout45%nTheSCWRuseswaterasbothcoolantandmoderator;theneutronspectrummaybeeitherthermalorfast,dependingonthequantityofwaterinthecore.Additionalmoderatorsmayalsobeused.nAlower-coolantmassinventoryresultsfromtheonce-throughcoolantpathinthereactorvesselandthelower-coolantdensity.Thisopensthepossibilityofsmallercontainmentbuildings.nNoboilingcrisis(departurefromnucleateboilingordryout)existsduetothelackofasecondphaseinthereactor,therebyavoidingdiscontinuousheattransferregimeswithinthecoreduringnormaloperation.nSteam dryers,steam separators,recirculation pumps,and steamgeneratorsareeliminated.Therefore,theSCWRcanbeasimplerplantwithfewermajorcomponents.Supercritical Water-Cooled Reactor(SCWR)Unique characteristicsSupercritical Water-Cooled Reactor(SCWR)Safety System ConceptnThereactorcanbeshutdownusingcontrolrodsandaboratedwaterinjectionsystemthatmaintainsthereactorinasubcriticalstateduringthepost-accidentphase.nThe containment can be isolated by closing various valves;Pressure relief valves limit the water pressure in the reactorvessel.nAdecayheatremovalsystem(suppressionpool)limitspressureinthecontainment.nAnemergencyinjectionsystemisabletoinjectwaterintothereactorvessel.SCWR Achievement of Generation IV Goals nSustainability The fast-spectrum version of the SCWR would effectively address thesustainabilitygoalsbecauseitwouldallowforeffectiveutilizationoffuelinaclosedfuelcycle.nEconomics Forsimpledesignandpotentialabilitytoproduceelectricpoweratlowcosts,theSCWRwouldberankedhighinaddressingtheeconomicgoals.nSafety and Reliability and Proliferation Resistance and Physical Protection Both The general design characteristics of the SCWR also make it an attractivecandidate for addressingthe safety goals and the proliferationand physicalprotectiongoal.Summary of SCWR projectsSupercritical Water-Cooled Reactor(SCWR)VHTR（Thermal）SFR（Fast）MSR（Thermal/Fast）SCWR（Thermal/fast）GFR（Fast）LFR（Fast）OverviewnLiquidsodiumisusedasacoolantbecauseofitsgoodneutronproperties(lowmoderationeffectandlowneutronabsorbingcapability).Reactor ParametersReference ValueFuelOxideormetalalloyAveragepowerdensity350MWth/m3CoolantSodiumPressureAbout1AtmospheresCoreoutlettemperature530-550CladdingFerriticorODSferriticNetplantefficiencyAbout42%Sodium-Cooled Fast Reactors(SFR)Unique characteristicsnSFR can manage high-level wastes and,in particular,plutonium andotheractinides.nThereisarelativelylargethermalinertiaoftheprimarycoolant.Alargemargin to coolant boiling is achieved by design,and is an importantsafetyfeatureofthesesystems.nThe primary system operates at essentially atmospheric pressure,pressurizedonlytotheextentneededtomovefluid.Sodium-Cooled Fast Reactors(SFR)General Safety OptionsnLossofprimarycoolantismadehighlyunlikelybytheimplementationofadualwallthatsurroundstheprimarycircuitandisequippedwithaleakdetectionsystem.nThe volumeslocatedabove thefreelevelsofthesodiumcircuitsarerendered permanently inert and are protected from any ingress of air(positivepressureandinertgassweeping).nTheassemblycladdingtemperaturesaremonitoredduringoperationbyasystemthatreadstheassemblyoutlettemperaturesandwhichquicklydetectslocalblockages.Sodium-Cooled Fast Reactors(SFR)General Safety OptionsnThecoreisequippedwithacladdingfailuredetectionsystemconnectedtotheprotectionsystemandwithaleaklocalisationsystem.nTherisksassociatedwithpotentialsodiumleaksandfiresareaddressedbyadefence-in-depthstrategythatmakesuseofthedetection,isolationandrapiddrainagesystems(drainage-dedicatedcircuits).nThereactorbuildingprovidesdynamicconfinement(ventilation/filtrationsystem)andisgenerallydesignedtomanagesmallprimarysodiumfires.Sodium-Cooled Fast Reactors(SFR)nSustainability Rankinghighinaddressingthetwosustainabilitygoalsbecauseofitspotentialforeffectivelymanagingactinidesinaclosedfuelcycle.nEconomics Forpotentialdesigninnovationstoreduceinitialcapitalcosts.nSafety and Reliability Theenhancedsafetyfeaturessuchaslongthermalresponsetimeofthecore,largemargintocoolantboiling,andprimarysystemoperationatatmosphericpressurewilladdressthethreesafetyandreliabilitygoals.nProliferation Resistance and Physical Protection Additionaldesigninnovationscanbedevelopedtoaddressthegoal.SFR Achievement of Generation IV Goals Summary of SFR projectsSodium-Cooled Fast Reactors(SFR)VHTR（Thermal）SFR（Fast）MSR（Thermal/Fast）SCWR（Thermal/fast）GFR（Fast）LFR（Fast）OverviewParametersValue(Pb Large)Rating3600MWthCoolantPbCoolantpressureAtmospheresFuelNitridePrimaryFlowForcedOutletTemperature550Lead-Cooled Fast Reactor(LFR)nLFRsystemsarePborPb-Bialloy-cooledreactorswithafast-neutronspectrumandclosedfuelcycle.nIncludingalongrefuelingintervalbattery,amodularsystem,andalargemonolithicplant.Choices for reactors with lead as the coolantnThemoderatingandneutronabsorptioncapabilityofleadislow.nIntermediatecircuitisnotneededfortheLFR(becausethereisnoneedtoisolatetheprimarycoolantfromthesteamgenerator(SG)circuit)nThelowpressuredropcombinedwiththehighdensityandhighthermalexpansioncoefficientofleadfacilitatecorecoolingbynaturalconvection.Lead-Cooled Fast Reactor(LFR)CoolantMeltingpoint()Boilingpoint()Chemicalreactivity(w/airandwater)LeadBismuth1241670EssentiallyinertLead(Pb)3271737EssentiallyinertSodium(Na)98883HighlyreactiveSafety functionsnFor core cooling,LFR designs are generally characterized by theexistenceofstrongnaturalcirculationcharacteristics,andtheprovisionofpassive,redundant,anddiversedecayheatremoval(DHR)systems.nForconfinementofradioactivematerial,apool-typeLFRwithaguardvesselwouldnotsufferlossofprimarycoolant,evenintheeventoffailureofthereactorvessel.nFor reactor shutdown,LFR designs are equipped with redundant anddiversifiedcontrolrodsystems.PeculiartotheLFRisthehighbuoyancyoflead,whichfacilitatesrodinsertionfromthebottomofthecore.Lead-Cooled Fast Reactor(LFR)LFR Achievement of Generation IV Goals nSustainability Highratinginachievingthegoalsbecauseitcanbeusedinaclosedfuelcycle.nEconomics Economicgoalsareaddressedbythemodularnatureofthedesignsandtheoptiontoemploydifferentplantsizestomatchthedifferentmarketneeds.nSafety and Reliability ThesafetygoalsareaddressedprimarilybytheuseofarelativelybenignPborPbBiliquidalloyreactorcoolant.nProliferation Resistance and Physical Protection TheabilityofthedifferentLFRdesignstomeetthegoalisconsideredhighbecauseofthedesignofthelong-lifereactorcores.Summary of LFR projectsLead-Cooled Fast Reactor(LFR)VHTR（Thermal）SFR（Fast）MSR（Thermal/Fast）SCWR（Thermal/fast）GFR（Fast）LFR（Fast）OverviewParametersValueAveragepowerdensity100MWth/m3CoolantHelium/S-CO2PressureAt90barCoreoutlettemperatureAbout850ElectricpowerconversionBraytoncycleNetplantefficiencyAbout48%Gas-Cooled Fast Reactor(GFR)nTheGFRsystemfeaturesafast-spectrumhelium-cooledreactorandclosedfuelcycle.Design features nTheGFRdesignisidentifiedinGenerationIVInternationalForumdocumentsasthereactorconceptwithsignificantsustainability.Forminimizing its own spent fuel inventory and managing uraniumresourcesandactinidewastestreamsinfutureclosedfuelcycle.nHigh breeding ratios,shorter doubling times,and high powerdensities are characteristic design features of historical gas-cooledfastbreederreactorsnTheburnerversionofGFRsyieldshighertransmutationefficienciesinwastemanagementapplicationscenarios.Gas-Cooled Fast Reactor(GFR)Safety OptionsnDevelopacoremadeofrefractorymaterialsthatremainintactintheeventofloss-of-normal-coolingtransients.nDesigndecayheatremoval(DHR)systemscapableofoperatingbynaturalconvectionwhenthecoolantheliumpressureissufficient.Intheeventthattheprimarycircuitisdepressurized,useactivedecayheatremovalmeansforthefirst24hours,thennaturalconvection.nEnsureaminimumback-uppr
