nuclear analysis of the hcll blanket for the european demo

1.HCLL DEMO equatorial outboard blanket module.verticalstiffeningplates,iskeptthesecondcalledadvanced ver-ticalstiffeningplatesareremovedandthelastcalledadvanced+ withhorizontalstiffenin

Fusion Engineering and Design

j ou rn a l h o m epa g e : w w w e l s e v i e r c o m / l o c a t e / f u s e n g d e s

Jean-Charles Jaboulaya,∗, Giacomo Aielloa, Julien Auberta, Alexandro Morina,

Marc Troisneb

a CEA-Saclay, DEN, DM2S, F-91191 Gif-sur-Yvette, France

b INSTN, Internship at CEA, France

h i g h l i g h t s

•AcompletenuclearanalysisoftheDEMOHCLLhasbeencarriedoutatCEAwiththeTRIPOLI-4®MonteCarlocode

•TheTRIPOLI-4®DEMOtokamakmodelwasgeneratedbytheCADimporttoolMcCad

•SeveralHCLLblanketsdesignswereinvestigatedtoimprovethetritiumproduction

•Thereferencedesignwhichisacompromisebetweentritiumproductionandmechanicalrobustnessmetallcriteria(TBR,nuclearheating,DPA,He production)

a r t i c l e i n f o

Article history:

Received 12 September 2016

Received in revised form 24 January 2017

Accepted 27 January 2017

Available online xxx

Keywords:

DEMO

Neutronics

Blanket

HCLL

Tritium breeding

Nuclear heating

TRIPOLI-4 ®

a b s t r a c t

ThispaperpresentsthenuclearanalysisoftheEuropeanDEMObaseline2015withHCLLblanketcarried outwiththeTRIPOLI-4®MonteCarlocodeandtheJEFF-3.2nucleardatalibrary.TheTRIPOLI-4®model wasimportedfromCADusingtheMcCadtool.Aprocedurethatgeneratesthedetailed3Dmodel describ-ingalltheHCLLblanketinternalstructureswasdeveloped.Thisprocedureallowsparametrizationofthe blanketinternalstructuressuchasthenumberofcoolingplates,manifolds,etc.andthethicknessofthe stiffeninggridforinstance.Differentdesignvariantswerestudiedtoimprovethetritiumproduction Fromthispreviousstudyacompletenuclearanalysiswascarriedoutonapromisingdesignwhichisa compromisebetweentritiumproductionandmechanicalrobustness.Allcriteria(TBR,nuclearheating

incoilsanddisplacementdamageinvacuumvessel)aremetusingthisnewreferencedesign

©2017TheAuthors.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBY-NC-ND

license(http://creativecommons.org/licenses/by-nc-nd/4.0/)

1 Introduction

TheEUROfusionConsortium[1]developsaconceptualdesign

ofafusionpowerdemonstrator(DEMO)intheframeworkofthe

European“Horizon2020”innovationandresearchprogramme[2]

KeyissuesforDEMOaretritiumself-sufficiencyandheatremoval

forconversionintoelectricity.Thesefunctionsarefulfilledbythe

breedingblanketssurroundingtheplasmachamber

Within theBreeder Blanket project(WPBB) of EUROfusion’s

PowerPlantPhysicsandTechnology(PPPT)programme[3],CEA

isinchargeofthedesignoftheHeliumCooledLithiumLead(HCLL)

blanket[4]forDEMOincludingthenuclearanalyses.In WPBB’s

frameworkthreeotherblanketconceptsarerespectivelystudiedby

∗ Corresponding author.

E-mail address: jean-charles.jaboulay@cea.fr (J.-C Jaboulay).

KIT,ENEAandCIEMAT:theHeliumCooledPebbleBed(HCPB),the WaterCooledLithiumLead(WCLL)andtheDualCoolantLithium Lead(DCLL)

CEA’s nuclearanalysis approach is based on theTRIPOLI-4® MonteCarlocode[5]andtheJEFF-3.2[6]nucleardatalibrary.This wasvalidatedinpreviousHCLLnuclearanalysis[7].TheTritium BreedingRatio(TBR)evaluatedinthisanalysis,basedontheDEMO

2014baseline,isequalto1.07,whichisbelowthetargetvalueof1.1 [8].Toimprovethetritiumproduction,designmodificationshave beeninvestigated.Thereductionofthesteelamountandthe opti-misationofthemanifoldsscheme,toincreasetheBreedingZone (BZ),werethemainoptions

Tomodelthedifferentbreedingblanketdesignvariantsan auto-matedprocedurewasdevelopedtogeneratetheinternalstructures

in an empty segmentation Threedesigns with TBR≥1.1 (with DEMO2014baseline)havebeenidentified:onecalled optimised-conservative (beer box concept, with internal horizontal and http://dx.doi.org/10.1016/j.fusengdes.2017.01.050

0920-3796/© 2017 The Authors Published by Elsevier B.V This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4 0/ ).

Fig 1.HCLL DEMO equatorial outboard blanket module.

verticalstiffeningplates,iskept)thesecondcalledadvanced

(ver-ticalstiffeningplatesareremoved)andthelastcalledadvanced+

(withhorizontalstiffeningplatesonlyandnocoolingplates)

Finally,thesethreedesignvariantshavebeenimplementedin

thenewDEMObaselinecalled“EUDEMO12015”[9].Thispaper

presentsthenuclearanalysisperformedtoevaluatethedifferent

HCLLdesignoption

2 HCLL blanket design

TheHCLLbreedingblanketlayoutisamulti-modulesegment

design.Modulesareweldedinastiffpoloidalbackplateinorder

toformabanana-shapedsegmentationthatcanberemovedfrom

theupperportoftheDEMOreactor.TheBackSupportingStructure

(BSS)alsoworksasamanifold,collectinganddistributing

lithium-leadandheliumindifferentblanketmodules

Thedesign ofoutboard equatorialHCLL moduleisshown in

Fig.1[10].EachHCLLblanketmoduleconsistsofaEurofer [11]

steelboxformedbyaU-shapedplatecomposingthefirstandside

walls(coatedwitha2mmtungstenlayer)closedbytwocapson

thetopandbottomandonthebackbyasetofBackPlates(BP)and

tierodsTR(forBSSattachments)

Theblanketmodulestructureisreinforcedbyaninnergridof

verticalandhorizontalStiffeningPlates(vSP,hSP).Thestiffening

platesdefineanarrayofinternal cellswhere theBreederUnits

(BU)arelocated.TheeutecticPb-Li(enrichedto90%in6Li)flows

aroundparallelhorizontalCoolingPlates(CP).Aninletandanoutlet

chamberonthebreederunitbackplateensurethehelium

distribu-tionandcollectionfortheCoolingPlates(bottompartofFig.1).All

theplates,exceptthebackplatesconstitutingthemanifolds,have

internalcoolingchannelswitharectangularsection

Thereferencedesignusedinthepreviousanalysis[7](calledref

2014)hasthreecoolingplatesperbreederunitandthreehelium

manifolds:onefortheFirstWall(FW),oneforthestiffeningplates

andoneforthecoolingplates;theobtainedTBRis1.08(thishigher

valuecomparedtoresultsof[7],1.07,isduetogeometricalerror

corrections).ThreedesignvariantstoimprovetheTBRhavebeen

defined.Firstly,theoptimised-conservativethatkeepsthebeerbox

Table 1

Main parameters of the DEMO reactor baselines.

(lossofstiffness incapsarea)andpressure dropsincrease Fur-therdesigndevelopmentsareneededtosolvetheseproblems.The optimised-conservativedesignoffersarobustsolutiontomeetall thecriteriaanditisconsideredasthereferencedesign2016(ref 2016)

3 HCLL DEMO model

TheTRIPOLI-4® EUDEMO12015 HCLL model is basedon a genericCADmodelwithemptyblanketdevelopedatKIT[12].The parametersofthestudiedtokamakarepresentedinTable1 Com-paredtothepreviousbaselinebreedingblanketcoverageisnow biggerbecausethedivertorissmallerinthe2015DEMObaseline ThesegmentationCADmodeldeveloped bytheHCLL design team has been implemented in the generic model using the SALOME platform [13] The TRIPOLI-4® model was generated usingtheCADimporttoolMcCad[14].ToeaseCADimportonly emptymodulesareconsidered.Anautomatedprocedure,written

inpython,fillstheemptyblanketcellswiththeinternalstructures (FW,Caps,BPs,CPs,hSP,vSP,manifolds).Thisautomatedprocedure allowsparametrizationoftheBUtostudydifferentdesigns.Fig.2 showsaradial-poloidalcutofthetokamakwithHCLLblanket.Fig.3 showstheinternalstructure:stiffeninggrids,coolingplates,back platesandmanifoldsofthe2014referenceHCLLdesign

4 Results

In this section the obtained neutron wall loading, tritium breedingratio,nuclearheatingandneutronfluxdistributionare presented

4.1 Neutronwallloading Firstofall,theNeutronWallLoading(NWL)wascalculated.It

isdefinedbytheneutroncurrent(normalisedtothefusionpower) crossingthefirstwallsurfacedividedbythefirstwallarea;NWL

isexpressedinMW/m2.Toavoidbackscatteringofneutronsin thecurrenttallying(duetoreflectivesurface),neutronsmustbe discardedafterpassingthroughthefirstwall.Leakageconditions

atfirstwallsurfacesareusedinTRIPOLI-4® Fig.4showstheobtainedpoloidalNWL.Itwasestimatedoneach BreedingBlanketModule(BBM)firstwallsurfacesnumbered1–15 (seeFig.2).Themaximumvalueof1.4MW/m2isobtainedinthe outboardequatorialmodule,whileNWLintheinboardequatorial moduleisaround1.2MW/m2.AveragedBBMNWLis1.01MW/m2

Table 2

TBR for different design options (TBR contribution of manifolds and BSS is taken into account).

* In these cases BZ thickness was reduced by 31 mm to increase BSS thickness, MF thickness is divided by 2 and stiffening plates thickness are increased from 11 mm to

14 mm.

Fig 2. TRIPOLI-4 ®

plot of the EU DEMO1 2015 HCLL model.

Fig 3.Poloidal-radial cut of a breeding unit design ref 2014 with 3 CP and 3 helium

manifolds.

4.2 Tritiumbreedingratio

TheTBRwasevaluatedforthedifferentHCLLdesignvariants

anddifferentDEMObaselines;resultsarepresentedinTable2.The

newbaselinehasastrongimpactonTBR,usingthesameBUdesign

with3CPsand3manifolds(MF)theTBRincreaseby+0.07thanks

toahigherbreedingblanketcoverageduetoasmallerdivertor

NeverthelessthisTBRmarginwillbeconsumedconsideringfuture

probablemodifications(highheatfluxpanel,seconddivertor,etc.)

HCLLref.design2014and2016arenotdirectlycomparable(see*

belowTable2).AdvanceddesignshavegoodTBRperformancebut

thickercapsmustbetakenintoaccountinneutronicmodeltodraw

aconclusion

CFDanalysisoftheBSSshowedtoohighpressuredropinthe

inboardpart.AstudywascarriedouttoincreaseinboardBSS

thick-nesswiththeobjectivetokeepthesameTBRvalue.Thestrategy

employedistoreducetheinboardBZandcounterbalancetheTBR

Fig 4.NWL poloidal distribution.

lossbyoutboardBZthicknessincrease(outboardBSSdecrease).It hasbeenshownthatTBRcanbekeptreducinginboardBZ thick-nessbyXmmandincreasingoutboardBZthicknessbyXmmwith

X<60mm

4.3 Nuclearheating CalculatedvaluesofNuclearHeating(NH)inEUDEMO12015 HCLLcomponentsarereportedinTable3.Theenergy multiplica-tionfactor(ME)is1.2.Onlyresultsobtainedwiththeref.2016HCLL designarereported;thereareonlyveryslightdifferenceswiththe otherdesigns

ThepoloidalNHdistributionwithineachBBMisintherange from0.8MWto3.5MW(themaximumvalueisobtainedinthe outboardequatorialmodule)

4.4 Inboardshieldinganalysis

InthispartonlytheHCLLref.2016designwasstudied(no sig-nificantimpactintherearpartofthemachineoftheHCLLblanket designisexpectedsincetheneutronfluxintheBSSisquite simi-lar).Theneutronflux(Fig.6 nuclearheating(Fig.5 displacement damagerate(Fig.7)andheliumproduction(Fig.8)havebeen cal-culatedalongtheinboardmid-plane.Forapropercalculationmesh tallyfunctionwasnotused(toavoidquantityaveragingover dif-ferentmaterialsinamesh),thegeometricalcellswerediscretised (5cmthickness).Thenuclearquantityisaveragedonapoloidal heightof50cm(fromz=10toz=60mm).Variancereduction tech-niqueswereusedinTRIPOLI-4®simulationtoobtainresultswith reasonablylowstatisticalerrorsuptothetoroidalfieldcoilregion (lowerthan5%).Functionalitypresentedin[15],addressedto cou-pledneutronphotontransportbiasing,wasveryusefultosetthe

Table 3

Nuclear heating breakdown.

Fig 5. Nuclear power density radial profile across inboard mid-plane (NH in BZ

is given for the W armour, FW and then the LiPb in MF NH in the back plates is

around 0.3 W/cm 3 and 1 W/cm3 for the LiPb manifold, MF includes BSS region; the

horizontal black line represent the NH limit in TF coils: 5 × 10 −5 W/cm 3 ).

Fig 6.Inboard radial neutron flux profile (MF includes the BSS region; horizontal

black line represent the NH limit in TF coils: 10 9 n/cm 2 s).

Table4showsthemainquantityobtainedthroughtheinboard

mid-plane.TheHCLLref.2016designmetallthecriteria[8]:fast

Fig 7. Inboard radial displacement damage rate profile are given in steel, FW includes first wall (facing the plasma) and side wall.

Fig 8.Inboard radial helium production profile in steel, FW includes first wall (facing the plasma) and side wall.

neutronfluxinTFCisbelow109n/(cm2s),nuclearheatinginTFC

isbelow50W/m3,displacementsperatom(dpa)inVacuum Ves-sel(VV)for6fullpoweryear(fpy)isbelow2.75(1.6)andhelium productionfor1.57fpyintherearpartofthemanifoldisbelow1 atomicpartspermillion(appm),0.8appm

AsimulationwasdonewithathickerBSS(+35mmofhelium

toreducepressuredropintheinboardBSScf.4.2)toevaluatethe impactonNHincoils.ThisthickerBSScausesanincreaseoftheNH

incoilsby+0.6×10−5W/cm3,i.e.2.2×10−5W/cm3intotal,which

isstillbelowthelimit.Theothercriteriaarealsometwiththis geometry

Table 4

Main quantities in the first 5 cm of the main components along the inboard mid-plane.

a In the tungsten armour.

InthisstudyBSScellsarehomogeneous.Futureworkswillfocus

onabettermodellingoftheBSStoverifytheshieldingrequirement

intheinboardmid-plane

5 Conclusions

ThispaperpresentsthenuclearanalysisoftheHCLLblanketwith

thenewDEMObaseline.Severalbreedingblanketdesignvariants

werestudiedtoimprovethetritiumproduction.Areferencedesign

whichisacompromisebetweenTBRperformanceand

mechan-icalrobustnesswascompletelyanalysed.Thisdesignmetallthe

neutronicrequirements.Futureworkwillfocusontheadvanced

designs,inparticularontheimpactofthickercaps(thatwithstand

LOCAloading)onTBR.AbettermodellingoftheBSSisunderway

toverifyitsimpactoninboardshielding

Acknowledgments

This work has been carried out within the framework of

theEUROfusionConsortium and hasreceivedfundingfromthe

Euratomresearchandtrainingprogramme2014–2018undergrant

agreementno.633053.Theviewsandopinionsexpressedherein

donotnecessarilyreflectthoseoftheEuropeanCommission.The

authorswarmlythankYuefengQiuand LeiLufortheirhelp on

McCad

References

[1] https://www.euro-fusion.org/ [2] http://ec.europa.eu/programmes/horizon2020/ [3] L.V Boccaccini, et al., Objectives and status of EUROfusion DEMO blanket studies, ISFNT-12, 2015.

[4] G Aiello, J Aubert, et al., Development of the helium cooled lithium lead blanket for DEMO, Fus Eng Des 89 (October (7–8)) (2014) 1444–1450 [5] TRIPOLI-4 Project Team, TRIPOLI-4 version 8 User Guide, CEA-R-6316, 2013, February http://www.oecd-nea.org/tools/abstract/detail/nea-1716/ [6] JEFF-3.2 evaluated data library https://www.oecd-nea.org/dbforms/data/eva/ evatapes/jeff 32/

[7] J.-C Jaboulay, et al., Comparison over the nuclear analysis of the HCLL blanket for the European DEMO, Fus Eng Des (2016) 365–370.

[8] U Fischer, et al., Neutronics requirements for DEMO fusion power plant, Fus Eng Des (2015) 2134–2137.

[9] W Ronald, DEMO1 Reference Design – 2015 April (“EU DEMO1 2015”) – PROCESS One Page Output, Internal EUROfusion data.

[10] P Arena, et al., Thermal optimization of the helium-cooled lithium lead breeding zone layout design regarding TBR enhancement, 2017 (in this conference).

[11] B Van der Schaaf, et al., The development of Eurofer reduced activation steel, Fus Eng Des 69 (2003) 197–203.

[12] P Pereslavtsev, L Lu, 2015 generic DEMO CAD model for neutronic simulations, Internal EUROfusion data.

[13] SALOME platform www.salome-platform.org [14] McCad https://github.com/inr-kit/McCad-Salome-Docs [15] O Petit, et al., Variance reduction adjustment in Monte Carlo TRIPOLI-4 ®

neutron gamma coupled calculations, Prog Sci Technol 4 (2014) 408–412.