Small Modular Reactors – “The Real Nuclear …Small Modular Reactors – “The Real Nuclear Renaissance? ... availability of cheap shale gas. ... • High temperature gas cooled

Small Modular Reactors –“The Real Nuclear Renaissance?”Institute of Physics, Nuclear Industry GroupBirchwood, 25 May 2016

Juan Matthews FInstPDalton Nuclear Institute and School of MaterialsThe University of Manchester

PresentationtoIOP25May2016 1

Inthebeginning therewerejustsmallreactors


Large reactors

GEN I

Rea

ctor

pow

er (M

We)

GEN II GEN III

Medium reactors

Small reactors

Compact reactors

SmallreactormarketsThereareareessentiallytwomarketsforsmallreactors:1. SmallModularReactors(SMRs)

– Sizesfrom~20to300MWe– Designedforgridconnection– Needtocompetewithothergridgeneration

2. Verysmallreactors(compactreactors)– Sizesfrom~1to20MWe– Designedmainlyforoff-gridandisolatedgenerationbutcouldbe

integratedintoagrid– Needtobeeasilytransportableandinstalled– Needtocompetewithdieselandotheroff-gridgeneration

TheU-Batteryisanexampleof2,inthispresentationwelookat1.


USAinterestinSMRs• TheAmericaninterestinthe1980sforSMRswasdrivenbyEPRIandtheUSDepartmentofEnergyonastrategicbasis,lookingatrequirementsfornuclearpowerbothdomesticallyandforexport.

• Around2000thefocushadchangedtotheneedtoreplacecoalfiredpowerstationsinafragmentedderegulatedgenerationindustry.Thismomentumhas,atleasttemporarily,beenbrokenbytheavailabilityofcheapshalegas.

• TheUSDoEiscurrentlyrunninganSMRTechnicalLicensingSupportProgram


USDOEviewofSMRbenefits• Modularity:intwosenses– factoryfabricationofmodulesfora

simplerassemblyonsiteandreactorunitsasmodulesthatcanbeaddedtomatchdemand;

• LowerCapitalInvestment:lowerunitofinvestmentandlowerinvestmentperunitpowerfromfactoryfabricationandshorterconstructiontimes;

• SitingFlexibility:smallerfootprint,lessdemandinginfrastructureandpossibilityofsitingonexistingfossilsitesnearerhabitation;

• GainEfficiency:useofheatforindustryandotherapplicationsandcouplingwithothergenerationsourcesformoreefficiency;

• Non-proliferation:DependingontypeofSMRcouldleadtoreducedtransportandhandlingofnuclearmaterialsandlongerrefuellingtimes,possibilityofsealedfuelunits;

• InternationalMarketplace:Opensanewnuclearmarket.PresentationtoIOP25May2016 5

OtherpotentialadvantagesofSMRs

• Multiplebuildenablesreducedcoststhroughlearning;

• Enablesexistinglicensedsitestobeusedwherespaceislimited;

• Smallreactorscanfitintolimitedelectricalgridinremoteregions,islandsandindevelopingcountries;

• Smallreactorsaresimplerandmoreabletousenaturalconvectionandpassivesafetyfeaturesandtobelocatedunderground.


UKINTERESTINSMRS


UKfirstinterestinSMRs

• UKInterestinSMRsdatesbacktothelate1980swhenitwasrealisedthattheprivatisationoftheelectricitysupplyindustrywouldmaketheinvestmentinlargereactorsdifficult.

• Studiesatthattimelookedattheeffectofscaleoncostandtheindustrywasstillfirmlylookingatlargereactors.

• TheUK(RollsRoyceandAEATechnology)joinedtheSIRproject(SafeIntegralReactor)withABBandStone&Webster,butintheendthedashforgaswon.


UKcurrentinterestinSMRs

• UKNuclearIndustrialStrategy,March2013:“TobeakeypartnerofchoiceincommercialisingGenerationIII+,IVandSmallModularReactor(SMR)technologiesworldwide”.

• NIRAB(NuclearInnovationandResearchAdvisoryBoard)initiatedafeasibilitystudywithBISsupportin2014.

• ThefeasibilitystudywaspublishedinDecember2014bytheNationalNuclearLaboratoryandfocussedontheintegralPWRdesign.

• InMay2015,DECCcommissionedanin-depthTechno-EconomicAssessment,whichhasjustreported.Thiscovers:theeconomiccase;gridintegration,marketassessmentandfuturetrends;safetyandmanufacturing.


UKcurrentinterestinSMRs

• AreportbytheEnergyTechnologiesInstitutepublishedinOctober2015looksatSMRsitingandidentifiesSMRsasasolutiontotheshortageofnewnuclearsitesandthelackofalowcarbonsolutiontoenergyforheating.

• TheGovernmentSpendingReviewinNovember2015,specificallymentionedsmallmodularreactorsinthecontextof£250millionincreasedfundingfornuclear.

• The2016Budgetalsomentionedsmallmodularreactors.• TheGovernmentisnowmovingtoassessdesignsandlead

companiestodecideifiswillsupportanSMRproject.• A£30million“PhaseOne”ofacompetitionwasannounced

on17March2016andbidshadtobeinplaceby6May.AroadmapwillbepublishedinSeptember2016.


WhatistheUKlookingfor• SMRspresentanopportunityfortheUKtohaveastakeinthe

developmentofasystemthatmayleadeventuallytoinvolvementinGENIVreactorconstructionandtobeglobalnuclearplayeragain.

• ThehopeistofindaprojectpartnerthatwillmakespaceforUKparticipationandIPgeneration– perhapsonthemodelofhowaircraftarebuilt.

• TherearecurrentlytoomanySMRsdesigns.Inevitablymostwillfailbutthewinnerscouldeventuallypickup100soforders.Thetrickistopickthewinner.

• ThenumberofsitessuitableforlargereactorsislimitedandSMRsareanopportunitytousesmallersites,oftennearercentresofpopulation,toexpandnuclearcapacity.


PotentialmarketforSMRs


Source: NNL SMR feasibility study 2014

The more recent ETI study suggests this may be an underestimate as the estimate up to 21 GWe for the UK by 2050 worth £60 billion.

EnergyTechnologiesInstituteStudy

SmallModularReactors– UKEnergySystemRequirementsForCogeneration(October2015)• Needfornuclearpowertocontributetoheatsupplyas

wellaselectricitygeneration• Needformoreflexiblegeneration- loadfollowing• NeedtousesitestoosmallforGWestations• Needtoremovedependenceoncoolingwater• Needtositesmallerstationsclosertoconurbationsto

allowtheuseofheatforindustryandhomes• Potentialtouseover20GWeofSMRcapacityby2040!


14PresentationtoIOP25May2016

CurrentandhistoricthermalpowerstationlocationsinEnglandandWalesFrom“Powerplantsitingstudy”August2015,preparedfortheETIbyAtkins.

WHATSMRDESIGNSAREWECONSIDERING?


RangeofSMRconcepts• Inadditiontosmallversionsofcurrentreactors,thereareover 60 SMR

conceptsthathavebeenstudiedinthelast10yearsbutfewarelikelytobebuilt.

• ThemainthrustofrecentSMRdevelopmentiswithIntegralPWRs – PWRswherethesteamgeneratorisintegratedintothereactorpressurevessel(RPV).Wewillfocusonthisdirectionasseveraldesignsareclosetomarket

• Hightemperaturegascooledreactorsareinherentlysmallreactorstoenableheatremovalinlossofcoolantaccidents.WehavetheUKU-BatteryverysmallreactorprojectandChinaisbuildingatwin105MWepebblebedreactorstation.

• Anumberofsmallsodiumandleadalloycooledfastreactordesigns–atonetimelookedliketheymightbebuiltbutcurrentlyareseenasasteptoofarforSMRdevelopment.

• Thereisarecentinterestinmoltensaltreactors,whichwouldbeintheSMRrange.


ThebasiccomponentsofaPWR

Core

To coastal, river or cooling towerheat sink

Primary circuit

Secondary circuit

SourceUSNRC

Primary pump


IntegralPWR(originmarinereactors- OttoHahn,submarines)

SteamoutletSteam

generatorControl rods

Primary pump

Core

Secondary circuit

Primary circuit

Secondary pump

Water inlet

ApologiestoUSNRCformergingtheirPWRandBWRanimatedGIFsPresentationtoIOP25May2016 18

Pressurizer

IntegralPWRconceptsPowerMWthMWe

RPVsize(m)DiameterHeight

Coresize(m)DiameterHeight

Primarycircuit

SIR(UK,USA) 1000 320 5.8 19.2 2.8 3.6 Forced

IRIS(international) 1000 335 6.2 21.3 2.3 4.26 Forced

CAREM(Argentina) 100 25 3.2 11 1.1 1.4 Natural

ACP-100*(China) 310 100 3.19 10 1.85 2.15 Forced

SMART(SKorea) 330 100 6.5 18.5 1.85 2.0 Forced

mPower(USA) 530 180 4 27 2.0 2.4 Forced

NuScale (USA) 160 50 2.9 17.4 1.5 2.0 Natural

Westinghouse SMR 800 225 3.7 28 2.3 2.4 Forced

SMR160**(USA) 525 160 2.7 15 1.64 3.7 Natural

IMR(MHI)(Japan 1000 350 6.0 16.8 2.95 2.4 Natural

RITM200*(Russia) 175 50 3.3 8.5 2.2 1.65 Forced


*External pressuriser **Steam generators and pressurizer section of RPV offset with a dog-leg

AdvantagesoftheintegralPWRconcept

CarefuldesignwillgiveaconsiderablereductionintheNSSScostbutthemainadvantagesarerelatedtothesafetyofthesystem• TheprimarycircuitiskeptentirelywithintheRPV,sono

primarypipeworkandnoactivecircuitoutsideRPV• NopenetrationsoftheRPVlargerthan50mmdiametersono

largebreaklossofcoolantaccidents• IncreasedshieldingofRPVfromfastneutrons• LowercorepowerdensityandlargervolumeofwaterinRPV• Largersurfaceareatopowerratio,makingpassivedecayheat

removaleasier• UsesstandardPWRfuel,butwithshorterfuelrods.


SafeIntegralReactor(SIR)

Power– 300MWePowerdensity– 55MW/m3(similartoBWR)Specialdesignfeatures– 12modularsteamgenerators,integralwithRPVThereisanextremelylowfastneutrondosetothereactorpressurevesselbecauseofthelargewatergapbetweenthereactorcoreandthevesselwall.Vesseldiameter– 5.8mVesselheight– 19.2m

PresentationtoIOP25May2016 21Source: Matzie et al, Nucl. Eng. and Design 136 (1992) 73

PresentationtoIOP25May2016 22Source: IAEA

Primary pumps

Steam generators8 helical once through modules

• IRIS(InternationalSecureandInnovative)wasacollaborationledbyWestinghouse thatincludedBNFLintheUKandorganisations inItaly,Spain,Russia,BrazilandJapan.

• Themaindesignworkwasdone intheearly2000s,buttheinfluenceoftheprojectcanbeseeninallcurrentintegralPWRdesigns.

• Thedesign isjustoutside thenormaldefinition ofanSMRat335MWe.

• IRIShasthefeaturesthatcanbeseenindesignsliketheWestinghouseSMR,mPower,SMART,CAREMandsomeRussiandesigns

• IRISisclearlyinfluenced bytheSIRdesign(Westinghouse acquiredABBCombustionEngineering) but themaininnovation isthesealedCRDMinside theRPV.

Core

Pressurizer

CRDM

PresentationtoIOP25May2016 23Source: Westinghouse

• Westinghouse hasmovedonfromitsroleinIRIStocreateitsown225MWeSMRdesignClaimedtobederivedfromtheAP1000designbutclearlybuiltontheIRISexperience

• Thedesign ismuch longerandthinner thanIRISandasecondflangeisaddedbelowthesteamgeneratorstoalloweasieraccesstothecoreforfuelreloading.Thecoolantpumpsarealsolocatedlower.

• TheWestinghouse design iswelldevelopedandhasadvancedalongtheUSNRCapprovalbuttherearenospecificplanstobuildafirstplant.Westinghousehavebeenlobbying theUKGovernmentsincethe2015Spending Review.

© Westinghouse Electric Co

PresentationtoIOP25May2016 24Source: Generation mPower LLC

Discussion on construction on the TVA Clinch River Site. Plan to submit Design Certification application to the NRC by late-2014 for approval by 2018

180530

• ThemPowerdesigncomesfromB&WintheUSAandwasbeingdevelopedasaJVwithBechtel.Itissaidtobebasedon itsexperiencewithUSnavalreactors,buttheinfluenceof IRISisobvious

• Thedesignhasbeen ratedatvariouspowersbutcurrentlyaimstodeliver180MWe.Inmanyrespectsthedesign isverysimilartothatofWestinghouse butthecoolantpumpsarestilllocatedatthetopoftheRPV.

• Thecontainmentconceptislessambitious thanWestinghouse, NuScaleorACP-1000,withalargerdrycontainment.

• Afteraverybullish start,severalUSDoEgrantsandsubstantialinvestmentbyB&W,theprojectsisnowessentiallymothballed.B&Warelookingforapartnertotakeamajority stake,butstillhopes tobethemainmanufacturer.

© Generation mPower LLC

PresentationtoIOP25May2016 25Source: NuScale

2016

• NuScalestartedasaconceptatofOregonStateUniversityandIdahoNationalLaboratorybutisnowbeingdevelopedbyFluor.Fromthepointofviewofcontainmentandheatremovalitisthemostinnovativeofthenewdesigns.

• AstheonlydesigntheUKislooking at,thatusesnaturalconvectionduring normaloperation, thereactorpowerisjust50MWe.Itisintendedtobeusedinblocksofupto12modules (atotalofonly600MWe).Despitethisanovernightcostofonly$5000/kWeisclaimed

• TheCRDMsystemisexternalusingconventionaltechnology, whichmeansthelinkagesareverylong.

• RollsRoycehasgivensupport toNuScaleinitsUSDoEfunding applications.CurrentlytheplansaretobuildthefirstplantatIdahoanditisexpectedthattheconstructionandoperationlicenceapplicationtoUSNRCwillbemadein2017,NuScalearelobbyingtheUKGovernmentsincethe2015Spending Review.© NuScale Power LLC

• TheIntegralPWRprojectclosesttoimplementationisthetheChineseACP-100designwhichiscurrentlybeingassessedforsafetybytheIAEAandconstructioniswaitingCentralCommitteeapproval.

• Thedesignfora100MWereactorisbeingreplacedwitha120MWedevelopmentwithseveralimportantdesignimprovements,notablyplacingtheCRDMandpressurizerinsidetheRPV.

• ThenewreactorisdesignatedforthetimebeingasACP100+andthisdesignistheonethattheUKislookingatapossibledevelopmentpartnership.

PresentationtoIOP25May2016 26Source: CNNC

ACP-100 and ACP-100+ (CNNC, China)

Primary pumps

Steam generators

Core

Pressurizer

CRDM

ACP-100+

SIZEMATTERS


Effectofeconomiesofscaleonreactorsize


Source: Locatelli et al, Prog. in Nucl. Energy, 73 (2014) 75.

Isreactorconstructiontimerelatedtoreactorpower?

29

Japanese construction times

BWR

PWR

PresentationtoIOP25May2016

0

2

4

6

8

10

12

0 200 400 600 800 1000 1200 1400

Timeformstarto

fconstructiontocc

ommercia

loperatio

n(years)

Reactornetpower (MWe)

Claimedconstructiontimes(fromfirstconcretetogridconnection)


ABWR

ATMEA

DMR (Hitachi)

EPR

AP 1000APR1400

VVER 1200

RITM 200

NuScale

mPowerSmart

IMR (MHI)

SMR 160

WestinghouseSMR

Current SMRsconcepts

Main vendor offerings

Variationofreactorvesseldiameterwithpower

PresentationtoIOP20April2016 31

P µr2P µr3

SMRs

NuScaleSMR160

SMART

WestinghousemPower

ACP100

CAREM

ABV 6MRITM 200

IRISIMRSIR

1

10

10 100 1000 10000

Reactorv

esselin

nerd

iameter(m

)

ThermalPower (MW)

PWR IntegralPWR

∝ ∝

Variationofreactorvesseldiameterwithpower


P � r2P � r3

SMRs

1

10

10 100 1000 10000

Reactorv

esselin

nerd

iameter(m

)

ThermalPower (MW)

PWR BWR IntegralPWR HTGR LMFBR

ComparisonofsizeofNSSSofanSMRtoaregularPWR


SMART NSSSNet power 100 MWe

mPower NSSSNet power 180 MWe

AP 1000 NSSS net power 1117 MWe

4.4m OD4m OD6.5m OD

12m

27m

18.5m

Source: IAEA ARIS data and images


NuScale unit45 MWe

mPower unit180 MWe

AP10001117 MWe

Source: IAEA ARIS data

ComparisonofsizeofprimarycontainmentforintegralandregularPWRs.

Westinghouse unit225 MWe

PrimarycontainmentofWestinghouseSMR

PresentationtoIOP25May2016 35Source: Westinghouse© Westinghouse Electric Co

SMRContainment


Modules with own containment in water pond in concrete cells

Containment

Reactor vessel

• Oneoftheopportunities forSMRsafetydesign istochooseasmall-volumepressuresuppression containmentmoreusuallyfoundwithBWRsystems.

• TheNuScale,Westinghouse andACP-100+designshavebelowground tightsteelhighpressurecontainments.

• Westinghouse andNuScalecanoperatewiththecontainmentundervacuum,sothatthereactorhasnoinsulationandiseasiertocoolbyflooding thecontainment inalossofcoolingaccident.

• TheWestinghouse andACP-100+containmentshaveinternalwaterreservoirsforpressuresuppression.

• TheNuScaledesignhasupto12reactorssittinginalargefuelhandling pool.

NuScale

Source: NuScale

© NuScale Power LLC

FootprintofSMRs– aretheysmaller?


Reactor Nuclearislandarea Nuclearandnon-nuclearIslandarea

Totalarea

m2 m2/MWe m2 m2/MWe Hectares m2/MWe

CurrentdesignsrelevanttoUKEPR ~10000 6 ~25000 15 Twin170 ~500

AP1000 ~5000 4.5 ~10000 9 Twin125 ~560

ABWR ~3250 2.5 ~7500 5.5 Twin 50 ~185SMRdesigns

mPower ~1225 7 ~3675 20 Twin16 ~450

Westinghouse SMR ~1124 5 ~4500 20 Single6.5 ~290

NuScale ~1458 32 ~6561 146 x1218 ~333

SMART ~3600 36 ~7200 72 Single~9 ~900

HTR-PM ~1300 12.5 ~3000 29 Twin~2 ~100

SMRs occupy less land in absolute terms but are comparable relatively

WHATARETHESMRCHALLENGESFORTHEUK?


OvernightcostsofUSnuclearplant


AP 1000US EIS data

Range of US SMR claims

SMRovernightcapitalcostestimates


Data from “SMR feasibility study”, National Nuclear Laboratory, December 2014The study had access to 4 of the best developed SMR design, the “adjusted” data is where the original vendor data was reassessed by the study team.

£/kW

e

SMRlevelisedelectricitycostestimates


Levelised cost estimates are shown for discount rates of 5%, 8% and 10% for FY 2012 £sData from “SMR feasibility study”, National Nuclear Laboratory, December 2014

Importanceofreducing manufacturingcosts• AnEnergyTechnologies

InstitutestudyhasshowthatoverturningtheeconomiesofscaleforSMRisvitaltotheirviability.

• Theuseoffactoryproduction toreducecostsmightbeawayofgettingsubstantialcostreductionwithproduction ofmanyunits.

• TheuseofresidualheatfordistrictheatmakestheviabilityofSMRmuchmoreattainable.


CostmodelprojectionsandbreakevencapexlevelsforelectricityonlygenericSMRsFrom“Theroleofnuclearinalowcarbonenergysystem”andEnergyTechnologiesInstituteInsightReportOctober2015.

ETIstudyoncostreduction


From: “System requirements for alternative nuclear technologies” Mott MacDonald Report the Energy Technologies Institute, August 2015.

(Weighted averagecapital cost)

250

200

150

100

50

0

WhatcanweconcludeaboutSMRcosts?• SMRsshouldbebuiltinsubstantiallyshortertimesthan

largerreactors• SMRswilloccupymuchlesslandthanlargerreactorsbut

theareaoccupied/kWeisnotverydifferent.• Overnightcosts/kWeofSMRsaresimilartothoseof

largerreactors.• LevelisedcostsofelectricityfromSMRsmaybesmaller

thanfromlargerstations,butthereisalargeuncertaintywhichcanonlyberesolvedwhenanSMRbuildingprogramisstarted.

• TheunitcostofcapitalforatwinSMRstationisstilllargeforaderegulatedelectricityindustryataround£2billion.


Manufacturingissues

• TheonlywaytheovernightcostsforSMRscancompetewithlargerreactorsistohavesimplecompletelymodulardesignsthatcanbemadeefficientlyinfactoryconditionsandquicklyassembledonsite.

• IfSMRsaresuccessfulthenthenumberofsystemsbuiltcouldbehundredsandexperiencefromtheaircraftandautomotiveindustrymightbeuseful.

• Itwouldthenbeworthmakingtheinvestmentintoolingforautomatedfabrication


Modularconstruction• Modularconstructionshouldextendtothewholeplant.• Experiencefromtheaircraftindustryshowsthatcomplex

modules,weighing>100tonnescontainingmultipleservicescanbemadebydifferentfactoriesandassembledonsite,butitneedsprecision.

PresentationtoIOP25May2016 46A380 Module Source: Airbus

Modularconstructionforwholeplant

• Replacementofshutteringandrebarsettingwithstructuralmodulesforshieldwallsandmainplantstructures.Modulesarefilledwithconcreteonceinplace.

• Structuralmoduleswithbuilt-inpiping,cabletrays,ductwork,HI-VACandotherservices.

• Functionalmodulesthatcontainaplantsystems,egwatertreatment.

• Modulesneedtobesmallenoughtobetransportableandwherepossibletheyshouldbeinterchangeable.


SMRR&Dneeds• IntegralPWRsmostlyusethesametechnologyasotherLWRsandthesamefuel,reducedinlength.Sothematerials,fuelandstructuralintegrityissuesarethesameonesasbeingfacedinBWRsandPWRs,egZralloyoxidationandradiationdamageoftheRPV.

• ThereallydistinctissuesforSMRsarerelatedto:– specificdesignfeatures;– safety;– andmanufacture.

• ForlowerpowerSMRsthereisthepossibilityofcassettefuelreplacement.


NNUMANandNuclearAMRC• TherearetwomajoractivitiesintheUKattheheartof

advancednuclearmanufacturing:– TheEPSRCNewNuclearManufacturingprogram(NNUMAN)whichis

doesresearchatTRL2-4with£8millioninvestment.– An8000m2 researchfactory,with£30millioninvestment,atthe

NuclearAdvancedManufacturingResearchCentre(AMRC)


Manufacturing Technology Research Laboratory The University of Manchester

Nuclear AMRCResearch FactoryUniversity of Sheffield

Useofadvancedmanufacturingtechnology• Ithasprovedverydifficulttointroducethelatesttechnologies

intocurrentnewbuild,becauseofbarriersoflicensingofestablisheddesigns.

• SMRsofferanopportunitytoavoidthebarrier,decreasingcostsandmanufacturingtimes,whileimprovingreliability.

• TechnologybeingdevelopedbyNNUMANandtheNuclearAMRC– Electronandlaserwelding– narrowgap,thicksection– Automaticweldingofcomplexcomponents– steamgenerators– Assistedmachining– cryogenicmachining– Roboticmachiningandprocesstopartmanufacture– Diodelasercladdingofprimarycircuitfacingstructures– Nearnetshapeandadditivemanufacture– egHIP– State-ofthe-artmetrologywithvirtualandaugmentedreality


ModularstructureoftheRPVinthemPowerandWestinghousedesigns.


Westinghouse SMR mPower

PressurizerSteam generator

Mid-flangePumps

CRDM

Core

Upper flange

Steam outletand feedwater inlet


MaincomponentsforthemPowerNSSS

• Pressure14MPaMaxT320°C• Mainstructuralcomponents low

alloySA-508Gr.3steelwithprimaryfacingsurfacescladin308stainlesssteeloralloy57.

• Currentlylargestructuresarelikelytobeforgedandmachined.Claddingofsurfacesisdonebyoverlaywelding.Studiesarebeingdoneon theuseofpowdermetallurgicalmethods

• SteamgeneratortubesareAlloy609orasimilarnimonic.

• Thesecondarycircuitislargelybasedonlowalloysteelsotherearenotransitionwelds

Source: Sandusky and Lunceford, PNNL-22290 2013

• Corestructuresaremainlymadeof304Lor316nucleargradestainlesssteels,butthesehavepoorradiationresistance,largelythrough thehighnickelcontent.Noalternativesareavailableyetandthiscouldbealifelimitingfeatureoncomponents.

• Components likesupport gridsaremadebymachining largeforgingwithhigh fractionsofmaterialremoval,asweldedstructuresmaynotbeacceptable.Thereareopportunities fornewadvancedmanufacturingmethods


MaincomponentsforthemPowercorestructures



DifferencesfromthemPowerdesigninclude:• Norecirculatingpumpsasthe

systemusesnaturalconvection;• Controlroddrivemechanism

(CRDM)isexternalsothetopdomehasmanypenetrationsandthecontrolrodextensionsareverylong

• Thesteamgeneratorconfiguration istheopposite ofmPower– thesecondarycircuitpassesthrough theboiler tubes.

• Theprimarycontainmentisasteelvesselfittedtightlyaroundthereactorvessel.


MaincomponentsfortheNuScaleNSSSand

primarycontainment

Designissues• Primarycoolantpump

– Theprimarypumpsareusuallyfixedexternallyina“canneddesign”withapenetrationthroughtheRPVforthedrivetotheimpellors.Somedesignsdispensewithpumpsandoperatewhollyonnaturalconvection.

• Controlroddrivemechanism(CRDM)– ThelongRPVandthelocationofsteamgeneratorsandpressurizermakes

designoftheCRDMdifficult.SomedesignsuseasealedinternalCRDM.

• Steamgenerator– Thesteamgeneratorshavetobecompactandefficient.Manysystemsuse

modularsteamgeneratorsthatcanbeisolatedandseparatelyremovedifthereisatubeleak.

• Pressurizer– Thelocationandsmallvolumeavailableforthepressurizerisachallenge.


WestinghouseSMRCRDM

“TheCRDMsareahigh-temperatureandpressureversionoftherecentlydevelopedAP1000CRDM,whichhasalreadybeentestedtoeightmillionsteps,tobeusedwithinthepressureboundaryoftheSMRintegralreactor.Eliminationofcontrolrodpenetrationsthroughthereactorpressureboundaryhasresultedinreducedcostofmanufactureandtheeliminationofthenormally-postulatedrodejectionevent.”


Source: Nuclear Engineering International

Safetyissues• Smallerreactorsareeasiertocoolpassively• Somedesignsareveryconventionalintheirapproachtosafetysystems,butothers,notablyNuScale,taketheopportunitytocompletelyrethinkheattransferinaccidents.

• Theuseoftightlowvolumecontainments.• Sittingthecontainmentinalargevolumefuel-handlingwaterpool.

• Theuseofmultiplecoolingroutesandwithlowpowercoresthepossibilityofdrycoolingbyairconvectionwithoutthemeltingofthereactor.


NuScalesafetyfeatures

InoperationthereisavacuumbetweenthecontainmentvesselandtheRPV.ThereisnoneedforinsulationontheRPVmakinginspectioneasier.

Decayheatremovalfromexternalfeedwateraccumulatorsandfrommainwaterpool.Steamgeneratorsareusedtocoolprimarycircuit.

Emergencycorecoolingbypassiveconvectivecoolingbyfloodingcontainmentvessel.Anyprimarycircuitsteamisventedthroughreactorventvalves

Source:NuScalePowerLLCPresentationtoIOP25May2016 58© NuScale Power LLC

LongtermcoolinginNuScale

PresentationtoIOP25May2016 59© NuScale Power LLC

THATALLFOLKS!

[email protected]


Documents

Small Modular Reactors – “The Real Nuclear …Small Modular Reactors – “The Real Nuclear Renaissance? ... availability of cheap shale gas. ... • High temperature gas cooled