ML22258A185
| ML22258A185 | |
| Person / Time | |
|---|---|
| Site: | Hermes File:Kairos Power icon.png |
| Issue date: | 09/15/2022 |
| From: | Kairos Power |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML22258A182 | List: |
| References | |
| KP‐NRC‐2209‐011 | |
| Download: ML22258A185 (5) | |
Text
KPNRC2209011 ResponsetoNRCQuestiononFluidicDiodeTestingandPSARChapter4Changes (NonProprietary)
Page1of2 AspartoftheNRCgeneralauditofthePSAR,theNRCstaffaskedquestionsregardingthedevelopment programofthefluidicdiode.
AsdescribedinPSARSection4.3,thefluidicdiodesupportsasafetyrelatedheatremovalfunctionby supportinganadequateamountofnaturalcirculationflowinthereactorvessel.Toprovidethis function,thefluidicdevicesdesignisundergoinganongoingtestinganddevelopmentprogramas statedinPSARSection1.3.9.PSARSection4.6hasbeenupdatedtostatethatthedevelopmentprogram willincludequalificationorfunctionaltestingasrequiredbydesignverification.
ThePSARincludescommitmentstotestsafetyrelatedstructures,systems,andcomponentstoensure thesuccessfulperformanceofsafetyfunctions.AsdescribedinPSARChapter4,thefluidicdiodewill meetPDC4andPDC35.PDC4requiresthatthediodecanperformitssafetyfunctionunderthe environmentalconditionsassociatedwithnormalplantoperationaswellasduringpostulatedevents.
PDC35requiresthatthediodeperformsitssafetyfunctionbysupportingsufficientremovalofresidual coredecayheatfollowingpostulatedaccidentscenarios.AsdescribedinPSARChapter12,AppendixB, Section2.3.3,theadequacyofthedesignwillbeverifiedusingmethodsincludingtheperformanceof qualificationtests.Qualificationtestingforthefluidicdiodewillbedefinedinatestplanthatincludes appropriateacceptancecriteriaanddemonstratesthecomponentreliabilityandadequacyof performanceunderconditionsthatsimulatethemostadversedesignbasisconditions.
Asdiscussedabove,qualificationtestingmaybeusedaspartofthedesignverificationprocess.The designverificationwillcharacterizethebaselineflowandevaluatepotentialphenomenathatmayaffect theabilitytoremoveresidualcoredecayheatthroughnaturalcirculationflow,including:
((
))Thetestingplansarebasedonthepreliminarydesign,andfinaltestingneedswillbe determinedthroughpreliminarytests,detaileddesigndevelopment,andanalysis.
Thetestinganddevelopmentprogramwillprovidejustificationthatthediodeswillbeabletomaintain anadequateflowraterequiredtoremovedecayheatfromthecoreduringapostulatedevent.The programneededtovalidatethediodeperformanceinnormalandpostulatedeventconditionswillbe availablewiththeapplicationforanoperatinglicense.Theresultsofthisprogramneededtoqualifythe componentthroughstartupqualificationtestingwillbeavailableduringtheoperationphase.
Inaddition,thePSARincludescommitmentstoensurethecontinuedoperabilityofthefluidicdiode throughinspectionandmonitoring,whichensuresthatdegradationmechanismswillnotpreventthe fluidicdiodefromperformingitssafetyfunction.Section4.3.3commitsthediodetoPDC36andPDC37,
Page2of2 whichrequirethatthefunctionalityofthediodecanbeconfirmedthroughmonitoringandinspection.
AsdescribedinRAI339,themonitoringandinspectionstrategyforthediodewillensurethatthediode performsitssafetyfunctioninapostulatedevent.
PreliminarySafetyAnalysisReport
TheFacility KairosPowerHermesReactor 18 Revision0 1.3.9 ResearchandDevelopment Therequirementsin10CFR50.34(a)requirethatthePSARidentifythosestructures,systemsor componentsofthefacilitythatrequireadditionalresearchanddevelopmenttoconfirmtheadequacyof theirdesign;andidentificationanddescriptionoftheresearchanddevelopmentprogramwhichwillbe conductedtoresolveanysafetyquestionsassociatedwithsuchstructures,systems,orcomponents;and ascheduleoftheresearchanddevelopmentprogramshowingthatsuchsafetyquestionswillbe resolvedatorbeforethelatestdatestatedintheapplicationforcompletionofconstructionofthe facility.Suchadditionaldevelopmentactivitiesaredescribedbelow:
Performalaboratorytestingprogramtoconfirmfuelpebblebehavior(Section4.2.1)
Developahightemperaturematerialsurveillancesamplingprogramforthereactorvesseland internals(Section4.3.4)
PerformtestingofhightemperaturematerialtoqualifyAlloy316HandER1682(Section4.3)
Performanalysisrelatedtopotentialoxidationincertainpostulatedeventsforthequalificationof thegraphiteusedinthereflectorstructure(Section4.3)
Developmentandvalidationofcomputercodesforcoredesignandanalysismethodology (Section4.5)
Developandperformqualificationtestingforafluidicdiodedevice(Section4.6)
Justificationofthermodynamicdataandassociatedvaporpressurecorrelationsofrepresentative species.(Section5.1.3)
Completeevaluationsoftheintermediateandreactorcoolantchemicalinteraction(Section5.1.3)
Developprocesssensortechnologyforkeyreactorprocessvariables(Section7.5.3)
Developthereactorcoolantchemicalmonitoringinstrumentation(Section9.1.1) 1.3.10 References
- 1. KairosPowerLLC,PrincipalDesignCriteriafortheKairosPowerFluorideSaltCooledHigh TemperatureReactor,KPTR003NPA.
PreliminarySafetyAnalysisReport ReactorDescription KairosPowerHermesReactor
Revision0 454 4.6 THERMALHYDRAULICDESIGN 4.6.1 Description Thethermalhydraulicdesignofthereactorisacombinationofdesignfeaturesthatenableeffective heattransportfromthefuelpebbletothereactorcoolantandeventuallytotheheatrejectionsystem ofthereactor,consideringtheeffectsofbypassflowandflownonuniformity.Thedesignfeaturesthat playakeyroleinthethermalhydraulicdesignofthereactorsystemincludethefuelpebble(seeSection 4.2.1),reactorcoolant(seeSection5.1),reactorvesselandreactorvesselinternalstructures(see Section4.3),theprimaryheattransportsystem(PHTS)(seeSection5.1),andtheprimaryheatrejection system(PHRS)(seeSection5.2).
4.6.1.1 CoreGeometry Thecoregeometryismaintainedinpartbythereactorvesselinternalsincludingthereflectorblocks whichkeepthepebblesinageneralcylindricalcoreshape.Coolantinletchannelsinthegraphite reflectorblocksareemployedtolimitthecorepressuredrop.Theuseofpebblesinapackedbed configurationalsocreateslocalvelocityfieldsthatenhancepebbletocoolantheattransfer.Thereactor thermalhydraulicdesignusesthefollowingheattransfermechanismstoextractthefissionheat.
Pebbletocoolantconvectiveheattransfer
Pebbleradiativeheattransfer
Pebbletopebbleheattransferbypebblecontactconduction
Pebbletopebbleheattransferbyconductionthroughthereactorcoolant
Heattransfertothegraphitereflectorbymodesofconduction,convection,andradiation.
4.6.1.2 CoolantFlowPath Duringnormaloperation,reactorcoolantatapproximately550°Centersthereactorvesselfromtwo PHTScoldlegnozzlesandflowsthroughadowncomerformedbetweenthemetalliccorebarrelandthe reactorvesselshellasshowninFigure4.61.Thecoolantisdistributedalongthevesselbottomhead throughthereflectorsupportstructure,upthroughcoolantinletchannelsinthereflectorblocksandthe fuelingchuteandintothecorewithaportionofthecoolantbypassingthecoreviagapsbetweenthe reflectorblocks.Thecoolanttransfersheatfromfuelpebbleswhicharebuoyantinthecoolantand providescoolingtothereflectorblocksandthecontrolelementsviaengineeredbypassflow.Coolant travelsoutoftheactivecorethroughtheupperplenumviathecoolantoutletchannelsandexitsthe reactorvesselviathePHTSoutlet.Themaximumvesselexittemperatureis620°Canddependentonthe amountofcorrespondingbypassflowthroughthereflectorblocks.
DuringpostulatedeventswherethenormalheatremovalpaththroughthePHTSisnolongeravailable, includingwhenthePHTSisdrained,afluidicdiode(seeSection4.3),isusedtocreateanalternateflow path.Duringsuchevents,forcedflowfromtheprimarysaltpump(PSP)isalsonotavailable.Thefluidic diodethendirectsflowfromthehotwelltothedowncomerasshowninFigure4.61.Thisopensthe pathforcontinuousflowvianaturalcirculation.Duringnormaloperation,whilethePSPisinoperation, thefluidicdiodeminimizesreverseflow.Qualificationorfunctionaltestingplansforthefluidicdiodeas wellasanytestresultsneededtovalidateperformanceassumedinthesafetyanalysiswillbeavailable withtheapplicationforanoperatinglicense.