ML22250A680
| ML22250A680 | |
| Person / Time | |
|---|---|
| Site: | Hermes File:Kairos Power icon.png |
| Issue date: | 09/07/2022 |
| From: | Kairos Power |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML22250A678 | List: |
| References | |
| KP-NRC-2209-004 | |
| Download: ML22250A680 (3) | |
Text
KPNRC2209004
ChangestoPSARChapters4and5 (NonProprietary)
PreliminarySafetyAnalysisReport ReactorDescription KairosPowerHermesReactor
Revision0 432 HeavyloadconsiderationsareaddressedinSection9.8.4,CranesandRigging.Thesefeatures demonstratecompliancewithPDC4.
Corecoolingismaintainedthroughthedesignofthereactorvesselandthereactorvesselinternals.As describedinSection4.3.1.2,thevesselandvesselinternalsdefinethecoolantflowpath.Topreclude degradationtothevesselduetocorrosionofthestainlesssteel,thereflectorblocksandthevesselare baked(i.e.,heateduniformly)toremoveresidualmoisturepriortocomingintocontactwithcoolant.
Thereflectors,whichactasaheatsinkinthecore,arespacedtopreventtheformationoftensileand bendingstressesandaccommodatethermalexpansionandhydraulicforcesduringnormaloperation andpostulatedevents.Thegapsbetweenthegraphiteblockssupportcoolantflowtothereflectorthus maintainingacoolablecoregeometryandprecludingreflectordegradationbyoverheating.Maintaining acoolablecoregeometryandadequatecoolantflowthroughthecoreensuresthevesselwall temperatureisbelowdesignlimitswhichpreventvesselfailure.Dynamicbehaviorofthereactor,its support,anditsinternalsareanalyzedanddesignedtoensurevesselintegrityandcoregeometryare maintainedinadesignbasisearthquaketoadegreesufficienttoensurepassiveheatremoval.The vessel,aspartofthereactorcoolantboundary,ensuresthecontainmentofradionuclidesbyensuring thecoolantisconfinedandtheTRISOparticlesinthefuelpebblesareprotectedfromdamage.These featuresdemonstrateconformancetoPDC10.
TodemonstratecompliancewithPDC14,thereactorvesselisfabricated,erected,andtestedsoasto haveanextremelylowprobabilityofleakage,rapidlypropagatingfailure,andgrossrupture.Thereactor vesselmaterialsandweldmetalwillbequalifiedforuseasdescribedinKairosPowertopicalreport MetallicMaterialsQualificationfortheKairosPowerFluorideSaltCooledHighTemperatureReactor, KPTR013P(Reference3).The316HSSofthereactorvesselasfabricatedandtestedinaccordance withReference1standardshasahighfracturetoughnessatreactoroperatingconditions,thusreducing thelikelihoodofcrackpropagation.Thedesignofthereactorvesselandvesselinternalssupporta10 yearoperatinglifetime.Thisisaccomplishedbyoperatingthereactorvesselwithintheasdesigned operationalandtransientconditionstressesandbymonitoringforchanges(e.g.,irradiationand thermallyinduceddegradation,corrosion,creep)tothereactorvesselduringinserviceinspectionand testing.TheRVSSreactorvesselbottomheadinterfaceisdesignedtoallowaccessforweldinspections.
Thereactorvesseltopheadsupportsinserviceinspectionofattachmentsandpenetrations.
Thereactorvesselshellandbottomheadmaintainacoolantpathwayforcoolingthereactorcoreand ensuresubmergenceoffuelpebblesinthecore.Thereactorvesselisfabricated,erected,andtestedin accordancewithReference1asaClassAcomponenttoaccountforthermalandphysicalstressesduring normaloperationandpostulatedevents.Thevesselisfabricatedfrom316HSSbasemetalandER1682 weldmetalusingagastungstenarcweldingprocess.Reference1providesforweldmentstressrupture factorsuptoatemperatureof650°CforER1682weldmetalwith316Hbasemetal.Testingprovides stressrupturefactorsupto816°Cforweldmaterialwith316Hbasemetal(Reference3).Theplant controlsystemwilldetectleakagefromthereactorvesselandwithcatchbasins,asdescribedinSection 4.7,thatareusedtodetectleaksinnearbycoolantcarryingsystems.Thesefeaturesdemonstrate compliancewithPDC30.
Reactorvesselstressrupturefactorsaredeterminedupto816°Ctoencompasstransientconditions.
Thestressrupturefactorsaredeterminedbyacreeprupturetestonthevesselbasematerialwithweld metalunderthegastungstenarcweldingprocess.Thevesselprecludesmaterialcreep,fatigue,thermal, mechanical,andhydraulicstresses.Theleaktightdesignofthereactorvesselheadminimizesairingress intothecovergasandprecludescorrosionoftheinternals.Thehightemperature,highcarbongrade 316HSSofthecorebarrelandreflectorsupportstructurehavehighcreepstrengthandareresistantto radiationdamage,corrosionmechanisms,thermalaging,yielding,andexcessiveneutronabsorption.
PreliminarySafetyAnalysisReport
HeatTransportSystems
KairosPowerHermesReactor 54 Revision0 5.1.3 SystemEvaluation ThedesignofthenonsafetyrelatedPHTSissuchthatafailureofcomponentsofthePHTSdoesnot affecttheperformanceofsafetyrelatedSSCsduetoadesignbasisearthquake.Inadditiontoprotective barriers,thePHTSpipeconnectionstothereactorvesselnozzleshavesufficientlysmallwallthickness, suchthatifloadedbeyondelasticlimits,inelasticresponseoccursinthePHTSpipingwhichisnonsafety related.Thesefeatures,alongwiththeseismicdesigndescribedinSection3.5,demonstrate conformancewiththerequirementsinPDC2forthePHTS.
WhilethePHTSisaclosedsystem,thereareconceivablescenariosthatmayresultinthereleaseof radioactiveeffluents.Thefueldesignlocatesthefuelparticlesneartheperipheryofthefuelpebble, enhancingtheabilityofthefueltotransferheattothecoolant.Thethermalhydraulicanalysisofthe core(seeSection4.6)ensuresthatadequatecoolantflowismaintainedtoensurethatSARRDLs,as discussedinSection6.2,arenotexceeded.Thesefeaturesdemonstrateconformancewiththe requirementsinPDC10.
Thedesignofthereactorcoolant,inpart,ensuresthatpoweroscillationscannotresultinconditions exceedingSARRDLs.ThereactoriskeptnearambientpressureandthereactorcoolantinthePHTSdoes notexperiencetwophaseflow.Thecoolanthasahighthermalinertiamakingthereactorresilientto thermalhydraulicinstabilityevents.Thesefeatures,inpart,demonstrateconformancewiththe requirementsinPDC12.
ThefunctionalcontainmentisdescribedinSection6.2.Thedesignreliesprimarilyonthemultiple barrierswithintheTRISOfuelparticlestoensurethattheradiologicaldoseattheexclusionarea boundaryasaconsequenceofpostulatedeventsmeetsregulatorylimits.However,thereactorcoolant alsoservesasadistinctphysicalbarrierforfuelsubmergedinFlibebyprovidingretentionoffission productsthatescapethefuel.Thedesignofthereactorcoolantcompositionprovides,inpart,ameans tocontroltheaccidentalreleaseofradioactivematerialsduringnormalreactoroperationand postulatedevents(PDC60),andsupports,inpart,demonstrationofthefunctionalcontainmentaspects.
ThedesignaspectsofthereactorcoolantarediscussedinReference5.1.51.TheFlibealsoaccumulates radionuclidesfromfissionproducts,andtransmutationproductsfromtheFlibeandFlibeimpurities.The retentionpropertiesoftheFlibearecreditedinthesafetyanalysisasabarriertoreleaseof radionuclidesaccumulatedinthecoolant,andradionuclideconcentrationislimitedbytechnical specifications.ThetransportofradionuclidesthroughFlibeisbasedonthermodynamicdatathatwillbe justifiedintheapplicationforanOperatingLicense.Thesefeaturesdemonstrateconformancewiththe requirementsinPDC16.
Thefoulingandpluggingofthereactorcoolantflowpaththroughthevesselasaresultofareductionin coolantpurityisnotexpected.However,thetemperatureofthereactorcoolantinthedowncomerand corecanbemonitoredtodeterminedecreaseinheatremovalcapabilitythatcouldoccurasaresultof foulingorpluggingofpassages.ThisdemonstratesconformancewithPDC70.
ThedesignofthePHTScontrolsthereleaseofradioactivematerialsingaseousandliquideffluentsin theeventthePHTSworkingfluidisinadvertentlyreleasedtotheatmospherevialeaksinthepiping system.ThePHTSSSCsthatarepartofthereactorcoolantboundaryaredesignedtotheASMEB31.3 Code(forthepiping)andSectionVIII(forthePHX)suchthatleaksareunlikely.Meansareprovidedfor detectingand,totheextentpractical,identifyingthelocationofthesourceofreactorcoolantleakagein thePHTSSSCs.ApostulatedeventinthePHTSwouldbeaPHXtubefailure.ThiseventwouldcauseFlibe toleakintotheintermediatecoolant,astheFlibeismaintainedatahigherpressurethanthe intermediatecoolantandwouldresultinaspreadofcontaminationtothePHRS.Suchaneventwould