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
KPNRC 2209 011
Enclosure2 ResponsetoNRCQuestiononFluidicDiodeTestingandPSARChapter4Changes (NonProprietary)
AspartoftheNRCgeneralauditofthePSAR,theNRCstaff askedquestionsregardingthedevelopment programofthefluidicdiode.
Asdescribed in PSARSection4.3, thefluidicdiodesupportsasafetyrelatedheatremovalfunctionby supportinganadequateamountofnaturalcirculationflow inthereactor vessel.Toprovide this function,thefluidicdevicesdesignisundergoinganongoingtesting anddevelopmentprogramas stated inPSARSection1.3.9.PSARSection4.6hasbeenupdatedto statethatthedevelopmentprogram willincludequalificationorfunctional testingas requiredbydesignverification.
ThePSARincludescommitmentstotest safetyrelatedstructures, systems,andcomponentstoensure thesuccessfulperformanceofsafetyfunctions.AsdescribedinPSARChapter 4,thefluidicdiode will meetPDC 4andPDC 35.PDC4requiresthatthediodecanperformitssafetyfunctionunderthe environmentalconditionsassociated withnormalplant operationas well as duringpostulatedevents.
PDC 35 requiresthatthediodeperformsitssafetyfunctionbysupportingsufficientremovalofresidual coredecayheatfollowingpostulatedaccidentscenarios.AsdescribedinPSARChapter12,Appendix B, Section2.3.3,theadequacyofthedesign willbe verified using methodsincludingtheperformanceof qualificationtests.Qualificationtestingforthefluidicdiode willbedefined inatestplanthat includes appropriate acceptance criteriaanddemonstratesthecomponentreliabilityandadequacyof performanceunderconditionsthatsimulatethemostadversedesignbasisconditions.
Asdiscussedabove,qualificationtestingmaybeusedas partofthedesignverificationprocess.The design verificationwillcharacterizethebaselineflowandevaluatepotential phenomenathat mayaffect theabilitytoremoveresidualcoredecayheatthrough naturalcirculationflow,including:
((
))Thetestingplansarebasedonthepreliminarydesign,and final testingneedswillbe determinedthrough preliminarytests,detaileddesigndevelopment, andanalysis.
The testinganddevelopmentprogramwillprovide justificationthatthediodeswillbeabletomaintain anadequateflow rate requiredtoremovedecayheatfromthecoreduringapostulatedevent.The programneededtovalidatethediodeperformanceinnormalandpostulatedeventconditionswillbe availablewiththeapplicationforanoperatinglicense.Theresultsofthisprogramneededtoqualifythe componentthroughstartupqualificationtestingwillbeavailableduringtheoperationphase.
In addition,thePSARincludescommitmentstoensurethecontinuedoperability ofthefluidic diode throughinspectionandmonitoring,whichensuresthatdegradationmechanismswillnotpreventthe fluidicdiodefromperforming itssafetyfunction.Section 4.3.3commitsthediodetoPDC 36 andPDC 37,
Page1of2 whichrequirethat thefunctionalityofthediodecanbe confirmedthrough monitoringandinspection.
Asdescribed in RAI339,themonitoringandinspectionstrategy for thediodewillensurethat thediode performsitssafetyfunction inapostulatedevent.
Page2of2 PreliminarySafetyAnalysisReport TheFacility
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.
KairosPowerHermesReactor 18 Revision0 Preliminary Safety AnalysisReport ReactorDescription
4.6 THERMALHYDRAULIC DESIGN 4.6.1 Description Thethermal hydraulicdesignofthereactorisacombination ofdesignfeaturesthatenableeffective heattransportfromthefuelpebbletothereactorcoolantandeventuallytotheheatrejectionsystem ofthereactor,consideringtheeffectsofbypass flowandflownonuniformity.Thedesignfeaturesthat playakeyrolein thethermalhydraulic designofthereactor systeminclude thefuelpebble(seeSection 4.2.1),reactorcoolant(seeSection 5.1),reactor vesselandreactorvesselinternalstructures(see Section4.3),theprimary heattransportsystem(PHTS)(see Section5.1),andtheprimary heatrejection system(PHRS)(see Section5.2).
4.6.1.1 CoreGeometry Thecoregeometryismaintainedin partbythereactorvesselinternalsincludingthereflectorblocks whichkeepthepebblesinageneral cylindrical coreshape.Coolantinlet channelsin thegraphite reflectorblocksareemployedtolimit thecorepressuredrop.Theuseofpebblesin apackedbed configurationalsocreateslocalvelocityfieldsthatenhancepebbletocoolant heattransfer.Thereactor thermalhydraulic designusesthefollowingheattransfermechanismstoextractthefissionheat.
Pebbleto coolantconvectiveheattransfer Pebble radiativeheattransfer Pebbleto pebble heattransferbypebblecontactconduction Pebbleto pebble heattransferbyconductionthroughthereactorcoolant Heattransfertothegraphitereflector bymodesofconduction,convection,andradiation.
4.6.1.2 CoolantFlow Path During normaloperation,reactorcoolantatapproximately550°Centers thereactorvesselfromtwo PHTScold legnozzlesandflowsthroughadowncomerformed betweenthemetalliccorebarrelandthe reactorvesselshellasshown inFigure4.61.Thecoolantisdistributed alongthevesselbottomhead throughthereflectorsupportstructure,upthroughcoolantinletchannelsinthereflectorblocksandthe fuelingchuteand intothecorewithaportionofthecoolantbypassingthecoreviagapsbetweenthe reflector blocks.Thecoolanttransfersheatfromfuelpebbleswhicharebuoyantinthecoolantand providescooling tothereflectorblocksand thecontrolelementsviaengineeredbypassflow. Coolant travelsoutoftheactivecorethroughtheupperplenum viathecoolantoutletchannelsandexitsthe reactorvesselviathePHTSoutlet.Themaximum vesselexittemperatureis620°Cand dependentonthe amount ofcorrespondingbypassflowthroughthereflectorblocks.
During postulatedeventswherethenormal heatremovalpaththroughthePHTSisnolongeravailable, includingwhen thePHTSisdrained,afluidicdiode(seeSection4.3),isused tocreateanalternateflow path.Duringsuchevents, forcedflowfromtheprimary saltpump(PSP)isalsonotavailable.The fluidic diode thendirectsflowfromthehotwelltothedowncomerasshowninFigure4.61.Thisopensthe pathforcontinuousflowvianaturalcirculation.Duringnormaloperation,whilethe PSPisinoperation, the fluidic diodeminimizesreverseflow. Qualificationorfunctionaltestingplansforthe fluidicdiode as wellasanytestresultsneededtovalidateperformanceassumedinthesafetyanalysiswill beavailable withtheapplication foranoperatinglicense.
Kairos PowerHermesReactor Revision0454