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1、Nuclear Reactor EngineeringIntroduction of Generation IVAdvanced ReactorOverview1BackgroundofGenerationIVAdvancedReactorDescriptionsofGenerationIVAdvancedReactor3SummaryofGenerationIVAdvancedReactor2BackgroundNuclearpowerplantdevelopmentnGenI(1950-1970):TheearlyprototypereactorsnGenII(1970-1990):Com
2、mercialpowerplantsthatarestilloperatingtodaynGenIII/III+(1990-2030):OffersignificantadvancesinsafetyandeconomicsnGenIV(2030):SignificantlydifferentfromGenIII/III+,belongstothenuclearpowerrevolutionnIn2001,theUnitedStatesledtheestablishmentofGIF,whichaimstoresearchanddevelopthefourthgenerationnuclear
3、energysystem,andisexpectedtobeputintouseby2030.nMembers:US,China,UK,France,Canada,Japan,SouthKorea,Brazil,Argentina,etc.Generation IV International Forum,GIFBackgroundnSustainability1:Providesustainableenergygenerationthatmeetscleanairobjectivesandpromoteslong-termavailabilityofsystemsandeffectivefu
4、elutilizationforworldwideenergyproduction.nSustainability2:Minimizeandmanagetheirnuclearwasteandnotablyreducethelong-termstewardshipburden,therebyimprovingprotectionforthepublichealthandtheenvironment.nEconomics1:Haveaclearlife-cyclecostadvantageoverotherenergysources.nEconomics2:Havealeveloffinanci
5、alriskcomparabletootherenergyprojects.BackgroundGoalsforGenerationIVNuclearEnergySystemsnSafety and Reliability1:GenerationIVnuclearenergysystemsoperationswillexcelinsafetyandreliability.nSafety and Reliability2:Haveaverylowlikelihoodanddegreeofreactorcoredamage.nSafety and Reliability3:GenerationIV
6、nuclearenergysystemswilleliminatetheneedforoffsiteemergencyresponse.nProliferationResistanceandPhysicalProtection1:Increasetheassurancethattheyareaveryunattractiveandtheleastdesirableroutefordiversionortheftofweapons-usablematerials,andprovideincreasedphysicalprotectionagainstactsofterrorism.Backgro
7、undGoalsforGenerationIVNuclearEnergySystemsOverview1BackgroundofGenerationIVAdvancedReactorDescriptionsofGenerationIVAdvancedReactor3SummaryofGenerationIVAdvancedReactor2VHTR（Thermal）SFR（Fast）MSR（Thermal/Fast）SCWR（Thermal/fast）GFR（Fast）LFR（Fast）OverviewVery-High-Temperature Reactor(VHTR)ParametersVa
8、lueAveragepowerdensity610MWt/m3Coreoutlettemperature900ElectricpowerconversionDirect/indirectBraytoncycleNetplantefficiency45%nTheVHTRisagraphite-moderated,heliumcooledreactorwiththermalneutronspectrum.nGraphitealsoservesasastructuralmaterialforthecore.General DesignnTheVHTRisthenextgenerationinthed
9、evelopmentofhigh-temperaturereactors and is primarily dedicated to the cogeneration of electricity,hydrogen,andprocessheatforindustry.nThereactorcoretypeoftheVHTRcanbeaprismatic block coresuchastheoperatingHTTR,orapebble-bedcoresuchastheChineseHTR-10.nThecoreofaVHTRhasapowerdensityintherangeof4to10M
10、W/m3.Theheatoutputgenerallytargetedbydesignersisbetween250and600MWforathermodynamicefficiencyofaround45%.LiketheHTR,theVHTRisamodulardesign.Very-High-Temperature Reactor(VHTR)General Safety OptionsnThemainobjectiveinthedesignofaVHTRistopreventanyaccidentsthat may occur at the facility from leading t
11、o significant releases ofradioactivity.Mainsafetyoptionsas:nDesigningthecore(size,powerdensity,built-inreactivity)sothatthefuelcladdingandthestabilityofthecorestructuresareprotectedduringallaccidenttransientsusedforthesafetydemonstration;nDeterminingneutronfeedbackcoefficientsthatreducethereactorpow
12、erintheeventoflossofcooling(lossofheatsinkordepressurization)withouthavingtotriggeranemergencyshutdown;Very-High-Temperature Reactor(VHTR)General Safety OptionsnCooling of the reactor pit and the vessel(second barrier)by anexternalcircuitabletooperateinnaturalconvectionmode(especiallyincaseoflossofe
13、lectricalpowersupply);nContinuous high-efficiency purification and monitoring of primaryheliumactivitylevels;nInthecaseofasecondarywater/steamcircuit:limiting,bydesign,theamountofwaterthatcouldbeinjectedintothecoreintheeventofanaccident and mitigating the induced reactivity insertion(coreoptimizatio
14、n).Very-High-Temperature Reactor(VHTR)VHTR Achievement of Generation IV Goals nSustainability Notintendedtoaddresssustainabilitygoalsforutilizingaoncethroughopenfuelcycle.nEconomics Highratingfortheeconomicgoalsforitscapabilitytoproduceelectricityathigh power conversion efficiencies and provide high
15、-temperature thermalenergyforheatapplicationssuchastheproductionofhydrogen.nSafety and Reliability Highratingforsafetygoalsbecauseofinherentlysafedesignfeatures.nProliferation Resistance and Physical Protection Thegeneraldesignofthereactoranditsflexiblefuelcycleaddressesthegoal.Very-High-Temperature
16、 Reactor(VHTR)Summary of VHTR projectsVHTR（Thermal）SFR（Fast）MSR（Thermal/Fast）SCWR（Thermal/fast）GFR（Fast）LFR（Fast）OverviewParametersValueAveragepowerdensityAbout22MWth/m3CoolantMoltenfluoridesaltsModeratorGraphiteVaporpressure0.1psiCoreoutlettemperature700-850PowerCycleMulti-reheatrecuperativeheliumB
17、raytoncycleNetthermalefficiency44to50%Molten Salt Reactor System(MSR)nTheMSRproducesfissionpowerinacirculatingmoltensaltfuelmixture.nReactorsthatuseasolidfuelandamoltensaltcoolantUnique characteristicsnMSRs have good neutron economy,opening alternatives for actinideburningand/orhighconversionnMolten
18、fluoridesaltshaveaverylowvaporpressure,reducingstressesonthevesselandpipingnRefueling,processing,and fission product removal can be performedonline,potentiallyyieldinghighavailabilitynConceptualdesignactivitiesarecurrentlyunderwaysoastoascertainwhetherMoltenSaltFastReactor(MSFR)systemscansatisfytheg
19、oalsofGenerationIVreactorsMolten Salt Reactor System(MSR)General Safety OptionsnDevelopmaterialsresistanttohightemperatures,irradiation,erosionandcorrosioncausedbysalts;nDefinethegeometriccharacteristicsofthefuelsystemwithaviewtocontrolling salt reactivity,taking into consideration the intendedopera
20、tingtemperaturesandthechangesinfuelsaltcompositionoverthecourse of the operating cycle(which requires the strong relationshipbetweenthenuclear,thermal-hydraulicandthermochemicalaspectstobetakenintoaccount);Molten Salt Reactor System(MSR)General Safety OptionsnDesignafuelsaltemergencydrainingsystemto
21、enabledecayheatremovalfromthefuelduringoutagesandinaccidentconditions,andtokeepthesaltsubcritical;nAdopt measures to maintain the salt temperature above itssolidificationpointinallforeseeableconditions;nDefineaconfinementstrategywithappropriateconsiderationforthechemicaltoxicityofthesaltsusedandthep
22、roductsgeneratedduringreactoroperationandinthetreatmentunit.Molten Salt Reactor System(MSR)MSR Achievement of Generation IV Goals nSustainability Becausetheconceptofclosedfuelcycleandactinidesandothernuclearfuelbyproductscanbeburnedbyaddingtheseconstituentstothecirculatingliquidfuelinacontrolledfash
23、ion,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 Prot
24、ection 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 Rea
25、ctor(SCWR)ParametersValueAveragepowerdensityAbout100MWth/m3CoolantLight/heavywaterModeratorNo/heavywaterCoolantpressureAbout25MPaCoreoutletpressureAbout510ElectricpowerconversionBraytoncycleNetplantefficiencyAbout45%nTheSCWRuseswaterasbothcoolantandmoderator;theneutronspectrummaybeeitherthermalorfas
26、t,dependingonthequantityofwaterinthecore.Additionalmoderatorsmayalsobeused.nAlower-coolantmassinventoryresultsfromtheonce-throughcoolantpathinthereactorvesselandthelower-coolantdensity.Thisopensthepossibilityofsmallercontainmentbuildings.nNoboilingcrisis(departurefromnucleateboilingordryout)existsdu
27、etothelackofasecondphaseinthereactor,therebyavoidingdiscontinuousheattransferregimeswithinthecoreduringnormaloperation.nSteam dryers,steam separators,recirculation pumps,and steamgeneratorsareeliminated.Therefore,theSCWRcanbeasimplerplantwithfewermajorcomponents.Supercritical Water-Cooled Reactor(SC
28、WR)Unique characteristicsSupercritical Water-Cooled Reactor(SCWR)Safety System ConceptnThereactorcanbeshutdownusingcontrolrodsandaboratedwaterinjectionsystemthatmaintainsthereactorinasubcriticalstateduringthepost-accidentphase.nThe containment can be isolated by closing various valves;Pressure relie
29、f 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 effect
30、ively address thesustainabilitygoalsbecauseitwouldallowforeffectiveutilizationoffuelinaclosedfuelcycle.nEconomics Forsimpledesignandpotentialabilitytoproduceelectricpoweratlowcosts,theSCWRwouldberankedhighinaddressingtheeconomicgoals.nSafety and Reliability and Proliferation Resistance and Physical
31、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）G
32、FR（Fast）LFR（Fast）OverviewnLiquidsodiumisusedasacoolantbecauseofitsgoodneutronproperties(lowmoderationeffectandlowneutronabsorbingcapability).Reactor ParametersReference ValueFuelOxideormetalalloyAveragepowerdensity350MWth/m3CoolantSodiumPressureAbout1AtmospheresCoreoutlettemperature530-550CladdingFe
33、rriticorODSferriticNetplantefficiencyAbout42%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
34、 importantsafetyfeatureofthesesystems.nThe primary system operates at essentially atmospheric pressure,pressurizedonlytotheextentneededtomovefluid.Sodium-Cooled Fast Reactors(SFR)General Safety OptionsnLossofprimarycoolantismadehighlyunlikelybytheimplementationofadualwallthatsurroundstheprimarycircu
35、itandisequippedwithaleakdetectionsystem.nThe volumeslocatedabove thefreelevelsofthesodiumcircuitsarerendered permanently inert and are protected from any ingress of air(positivepressureandinertgassweeping).nTheassemblycladdingtemperaturesaremonitoredduringoperationbyasystemthatreadstheassemblyoutlet
36、temperaturesandwhichquicklydetectslocalblockages.Sodium-Cooled Fast Reactors(SFR)General Safety OptionsnThecoreisequippedwithacladdingfailuredetectionsystemconnectedtotheprotectionsystemandwithaleaklocalisationsystem.nTherisksassociatedwithpotentialsodiumleaksandfiresareaddressedbyadefence-in-depths
37、trategythatmakesuseofthedetection,isolationandrapiddrainagesystems(drainage-dedicatedcircuits).nThereactorbuildingprovidesdynamicconfinement(ventilation/filtrationsystem)andisgenerallydesignedtomanagesmallprimarysodiumfires.Sodium-Cooled Fast Reactors(SFR)nSustainability Rankinghighinaddressingthetw
38、osustainabilitygoalsbecauseofitspotentialforeffectivelymanagingactinidesinaclosedfuelcycle.nEconomics Forpotentialdesigninnovationstoreduceinitialcapitalcosts.nSafety and Reliability Theenhancedsafetyfeaturessuchaslongthermalresponsetimeofthecore,largemargintocoolantboiling,andprimarysystemoperation
39、atatmosphericpressurewilladdressthethreesafetyandreliabilitygoals.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（Therma
40、l/Fast）SCWR（Thermal/fast）GFR（Fast）LFR（Fast）OverviewParametersValue(Pb Large)Rating3600MWthCoolantPbCoolantpressureAtmospheresFuelNitridePrimaryFlowForcedOutletTemperature550Lead-Cooled Fast Reactor(LFR)nLFRsystemsarePborPb-Bialloy-cooledreactorswithafast-neutronspectrumandclosedfuelcycle.nIncludinga
41、longrefuelingintervalbattery,amodularsystem,andalargemonolithicplant.Choices for reactors with lead as the coolantnThemoderatingandneutronabsorptioncapabilityofleadislow.nIntermediatecircuitisnotneededfortheLFR(becausethereisnoneedtoisolatetheprimarycoolantfromthesteamgenerator(SG)circuit)nThelowpre
42、ssuredropcombinedwiththehighdensityandhighthermalexpansioncoefficientofleadfacilitatecorecoolingbynaturalconvection.Lead-Cooled Fast Reactor(LFR)CoolantMeltingpoint()Boilingpoint()Chemicalreactivity(w/airandwater)LeadBismuth1241670EssentiallyinertLead(Pb)3271737EssentiallyinertSodium(Na)98883Highlyr
43、eactiveSafety functionsnFor core cooling,LFR designs are generally characterized by theexistenceofstrongnaturalcirculationcharacteristics,andtheprovisionofpassive,redundant,anddiversedecayheatremoval(DHR)systems.nForconfinementofradioactivematerial,apool-typeLFRwithaguardvesselwouldnotsufferlossofpr
44、imarycoolant,evenintheeventoffailureofthereactorvessel.nFor reactor shutdown,LFR designs are equipped with redundant anddiversifiedcontrolrodsystems.PeculiartotheLFRisthehighbuoyancyoflead,whichfacilitatesrodinsertionfromthebottomofthecore.Lead-Cooled Fast Reactor(LFR)LFR Achievement of Generation I
45、V Goals nSustainability Highratinginachievingthegoalsbecauseitcanbeusedinaclosedfuelcycle.nEconomics Economicgoalsareaddressedbythemodularnatureofthedesignsandtheoptiontoemploydifferentplantsizestomatchthedifferentmarketneeds.nSafety and Reliability Thesafetygoalsareaddressedprimarilybytheuseofarela
46、tivelybenignPborPbBiliquidalloyreactorcoolant.nProliferation Resistance and Physical Protection TheabilityofthedifferentLFRdesignstomeetthegoalisconsideredhighbecauseofthedesignofthelong-lifereactorcores.Summary of LFR projectsLead-Cooled Fast Reactor(LFR)VHTR（Thermal）SFR（Fast）MSR（Thermal/Fast）SCWR（
47、Thermal/fast）GFR（Fast）LFR（Fast）OverviewParametersValueAveragepowerdensity100MWth/m3CoolantHelium/S-CO2PressureAt90barCoreoutlettemperatureAbout850ElectricpowerconversionBraytoncycleNetplantefficiencyAbout48%Gas-Cooled Fast Reactor(GFR)nTheGFRsystemfeaturesafast-spectrumhelium-cooledreactorandclosedf
48、uelcycle.Design features nTheGFRdesignisidentifiedinGenerationIVInternationalForumdocumentsasthereactorconceptwithsignificantsustainability.Forminimizing its own spent fuel inventory and managing uraniumresourcesandactinidewastestreamsinfutureclosedfuelcycle.nHigh breeding ratios,shorter doubling ti
49、mes,and high powerdensities are characteristic design features of historical gas-cooledfastbreederreactorsnTheburnerversionofGFRsyieldshighertransmutationefficienciesinwastemanagementapplicationscenarios.Gas-Cooled Fast Reactor(GFR)Safety OptionsnDevelopacoremadeofrefractorymaterialsthatremainintact
50、intheeventofloss-of-normal-coolingtransients.nDesigndecayheatremoval(DHR)systemscapableofoperatingbynaturalconvectionwhenthecoolantheliumpressureissufficient.Intheeventthattheprimarycircuitisdepressurized,useactivedecayheatremovalmeansforthefirst24hours,thennaturalconvection.nEnsureaminimumback-uppr