ML23115A395

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Kairos Power, LLC - Enclosure 1, Changes to Hermes PSAR Chapters 2, 3, 4, 7, 8, 9, 13, and 14
ML23115A395
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Issue date: 04/25/2023
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KP-NRC-2304-005
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KP-NRC-2304- 005

Enclosure 1 Changes to Hermes PSAR Chapters 2, 3, 4, 7, 8, 9, 13, and 14

(Non-Proprietary)

Preliminary Safety Analysis Report Site Characteristics Figure 2.1-2: Prominent Features in Site Area

Kairos Power Hermes Reactor 2-9 Revision 2 Preliminary Safety Analysis Report Site Characteristics

Source: Reference 1

Kairos Power Hermes Reactor 2-10 Revision 2 Preliminary Safety Analysis Report Site Characteristics Figure 2.1-3: Project Site Area and Zones Associated with the Facility

Kairos Power Hermes Reactor 2-12 Revision 2 Preliminary Safety Analysis Report Site Characteristics

Source: Reference 1

Kairos Power Hermes Reactor 2-13 Revision 2 PreliminarySafetyAnalysisReport DesignofStructures,Systems,andComponents

Table3.51:LoadCombinationsfortheSafetyRelatedPortionoftheReactorBuilding ServiceLevelLoad LoadCombination*

Category ANormal D+FL+To+Ro D+F+To+Ro+L+H+Ccr+Lr BSevereEnvironmental D+L+ToF+Ro+Eo+H D+L+TiF+Roi+EoH+W CExtremeEnvironmental D+L+H+F+Ccr+To+Ro+Ess D+F+H+L+Tos+Ros+WEtss DAbnormal D+F+L+H+Ta+Ra+CWcrt D+F+H+L+Ta+Ra+Ess

  • Loadcombinationreferstothetypesofloadsconsideredactingsimultaneously.Applicationof loadfactorsandspecificdetailsofloadcombinationeffectsarepertheapplicabledesign standard.

LoadNomenclature:

D Deadloads L Liveloads Lr Roofloads,includingsnoworrainasapplicable F Fluidloads S Soilloads Ccr Craneloadratedcapacity W Normalwindloads Wt Highwindloads(tornadoandhurricane),includingcorrespondingmissiles To Thermalloadsduringstartup,normaloperatingand,orshutdownconditions Ti ThermalloadsduringServiceLevelBloadings Ta ThermalloadsasaresultofaccidentconditionsandincludingToduringServiceLevelD loadings Ts ThermalloadsduringServiceLevelCloadings Ro Pipeandequipmentreactionsduringstartup,normaloperatingand,orshutdown conditions Ri PipereactionsduringServiceLevelBloadings Ra PipeandequipmentreactionsasaresultofaccidentconditionsandincludingRoduring ServiceLevelDloadings Rs PipereactionsduringServiceLevelCloadings Eo Loadsgeneratedby1/3ofdesignbasisearthquake(DBE)(thedesignbasisearthquakeis alsothesafeshutdownearthquake[SSE])

Ess LoadsgeneratedbySSEDBE Wt Accidentalloadsduetomissileimpacteffects

KairosPowerHermesReactor 329 Revision2 PreliminarySafetyAnalysisReport DesignofStructures,Systems,andComponents

3.6.2 ClassificationofStructures,Systems,andComponents SSCsareassignedsafety,seismic,andqualityclassificationsconsistentwiththeirsafetyfunctions.These classificationsaredescribedbelow.Table3.61providesasummaryoftheseclassificationsforallSSCs.

3.6.2.1 SafetyClassification SSCshavetwopossiblesafetyclassifications:safetyrelatedornonsafetyrelated.AnSSCisclassifiedas safetyrelatedifitmeetsthedefinitionofsafetyrelatedfrom10CFR50.2(withexceptionsasdescribed inSection1.2.3).FortheKPFHRtechnology,thedefinitionofsafetyrelatedismodifiedfrom10CFR 50.2,tobe:

Safetyrelatedstructures,systems,andcomponentsmeansthosestructures,systems,and componentsthatarereliedupontoremainfunctionalduringandfollowingdesignbasisevents toassure:

(1)Theintegrityoftheportionsofthereactorcoolantboundaryreliedupontomaintaincoolant levelabovetheactivecore; (2)Thecapabilitytoshutdownthereactorandmaintainitinasafeshutdowncondition;or (3)Thecapabilitytopreventormitigatetheconsequencesofaccidentswhichcouldresultin potentialoffsiteexposurescomparabletotheapplicableguidelineexposuressetforthin10CFR 50.34(a)(1)or10CFR100.11 NotethatfortheKPFHRtechnology,thedefinitionabovereflectsadeparturefromthedefinitionsin10 CFR50.2forlightwaterreactorsthatincludetheterminologyintegrityofthereactorcoolantpressure boundary.AsdescribedinSection1.2.3andtheRegulatoryAnalysisfortheKairosPowerSaltCooled, HighTemperatureReactorTopicalReport(Reference1),thisdepartureisnecessarybecausethe technologyassociatedwiththeKPFHRisbasedonanearatmosphericpressuredesignandthereactor coolantboundarydoesnotprovideasimilarpressurerelatedorfissionproductretentionfunctionas lightwaterreactorsforwhichthesedefinitionswerebased.

SSCsthatdonotmeetthedefinition,asmodifiedabove,areclassifiedasnonsafetyrelated.

3.6.2.2 SeismicClassification SSCsaredesignedaccordingtotheirsafetyclassification.SafetyrelatedSSCsareclassifiedasSDC3 consistentwithASCE4319(Reference2).Section3.4discussestheSDC3classificationandSection3.5 discussesrequirementsforSSCsthatarerequiredtomaintaintheirfunctionintheeventofadesign basisearthquake.Thedesignbasisearthquakeisalsothesafeshutdownearthquake(SSE).Allsafety relatedSSCsarelocatedinthesafetyrelatedportionoftheReactorBuilding,whichisdiscussedin Section3.5.1.

ThecreditedsafetysystemsdesignedtofunctioninapostulatedeventaredescribedinChapter13.For adesignbasisearthquake,theSDC3SSCsthatarereliedupontoperformaspecificcreditedsafety functionarelistedinTable3.61.

Safetyrelatedsystemsandcomponentsarequalifiedtomaintaintheirsafetyfunctionduringadesign basisearthquake,afteradesignbasisearthquake,orboth,dependingonthefunctionperformed.For example,thereactorvesselisrequiredtoperformitssafetyfunction(i.e.,maintainstructuralintegrity) bothduringandafteradesignbasisearthquake,whereasthedecayheatremovalsystemisrequiredto performitssafetyfunctiononlyaftertheevent,andnotduring.Thespecificsafetyfunction,therefore, isusedtodefinetheASCE4319LimitStatethatisusedtoqualifytheSDC3SSCs.

KairosPowerHermesReactor 333 Revision2 PreliminarySafetyAnalysisReport ReactorDescription

ConsistentwithPDC2,thereactorvesselandreactorvesselinternalsperformtheirsafetyfunctionsin theeventofasafeshutdowndesignbasisearthquakeandothernaturalphenomenahazards.

ConsistentwithPDC4,thereactorvesselandreactorvesselinternalsaccommodatetheenvironmental conditionsassociatedwithnormaloperation,maintenance,testing,andpostulatedevents.

ConsistentwithPDC10,thereactorvesselandinternalsmaintainageometryandcoolantflowpathto ensurethatthespecifiedacceptablesystemradionuclidereleasedesignlimits(SARRDLs)willnotbe exceededduringnormaloperationincludingpostulatedevents.

ConsistentwithPDC14,thereactorvesselisfabricatedandtestedtohaveanextremelylowprobability ofabnormalleakageorsuddenfailureofthereactorcoolantboundarybygrossrupture.

ConsistentwithPDC30,reactorvesselisfabricated,andtestedtoqualitystandards,andpreandin serviceinspections,aswellastestingwherepracticable,willbeusedtodetectandidentifythelocation ofcoolantleakage.

ConsistentwithPDC31,thereactorvesselhassufficientmargintowithstandstressesunderoperating, maintenance,testing,andpostulatedeventssuchthatthereactorcoolantboundarydoesnotdegrade duetotheeffectsofneutronembrittlement,corrosion,materialwear,fatigue,stressrupture,thermal loads,orfailureduetostressruptureandfracture.Thedesignshallaccountforresidual,steadystate, andtransientstressesandconsiderflawsize.

ConsistentwithPDC32,thereactorvesselpermitsinspection,monitoring,orfunctionaltestingof importantareasandfeaturestoassessstructuralintegrityandleaktightnessofthesafetyrelated portionsofthereactorcoolantboundary.

ConsistentwithPDC33,thecorebarreldesignincludesantisiphonfeaturestolimitreactorcoolant inventorylossintheeventofbreaksinthePHTScoldleg.

ConsistentwithPDC34,theflowpathestablishedbythereactorvesselinternalsisdesignedtosupport theremovalofdecayheatduringnormaloperationandpostulatedevents,suchthatSARRDLsandthe designconditionsofthesafetyrelatedelementsofthereactorcoolantboundaryarenotexceeded.

ConsistentwithPDC35,thereactorvesselinternalsaredesignedtomaintainstructuralintegrityto assuresufficientcorecoolingduringpostulatedeventsandtosupportremovalofdecayheat.Thesafety functionofthefluidicdiode,reflectorblocks,anddowncomeristomaintainaflowpaththatsupports naturalcirculationandtotransferheatfromthereactorcoreduringandfollowingpostulatedeventsto preventfuelandreactorinternalstructuredamagethatcouldinterferewithcontinuedeffectivecore cooling.

ConsistentwithPDC36andPDC37thefluidicdiodesaredesignedtopermitperiodicmonitoringand inspectiontoprovideassurancethattheintegrityofthenaturalcirculationflowpathfordecayheat removalismaintained.Thedesignofthedecayheatremovalnaturalcirculationflowpathprovidedby thedowncomer,graphitereflector,hotwell,diodepathwayandfluidicdiode,isalsocapableofbeing periodicallyconfirmedtoprovideassurancethattheintegrityofthenaturalcirculationflowpathfor decayheatremovalismaintained.

ConsistentwithPDC74,thedesignofthereactorvesselandreflectorblocksshallbesuchthattheir integrityandgeometryaremaintainedduringpostulatedeventstopermitsufficientinsertionofthe controlandshutdownelementsprovidingforreactorshutdown.

KairosPowerHermesReactor Revision2432 PreliminarySafetyAnalysisReport ReactorDescription

4.3.3 SystemEvaluation The316HSSstructuresofthereactorvesselsystemarefabricatedandtestedtomeettheintentof Reference1standardsasshowninTable3.62.The316HSSvesselinternalsalsosatisfythechemistry restrictionsoftheASMESectionIIIcodeinDivision5,ArticleHGB2000.PertheASMEstandard,ER168 2weldmetalwillbeusedinfabricationofthe316Hstructures.Commensuratewiththesafetyrelated functionofthereflectorblockinensuringacceptabledesignlimitsandmaintainingthereactorcoolant flowpath,qualityrelatedcontrolswillbeplacedontheET10graphite.Thegraphitereflectorwillbe designedtomeettheintentofReference1standardsshowninTable3.62.KPFHRspecificationsand procurementdocumentsincorporateandreferencetheapplicableguidanceandASMEstandards.The qualityassuranceprogramisdescribedinSection12.9.Thesecontrolsdemonstrateconformancewith PDC1.

Thereactorvesselsystemmakesupaportionofthereactorcoolantboundary.Thereactorvesseland graphitereflectorblocksarethereforedesignedtomaintaingeometryduringasafeshutdowndesign basisearthquaketoensurethevesselintegrity,insertionofnegativereactivityviatheRCSS,andto maintaintheflowpath.Thereactorvesselandvesselinternalswillhavedynamicbehaviorsduringa designbasisearthquake.Theseincludefluidstructureinteractionwithinthevessel,oscillatoryresponse ofcomponentsmountedtothereactortophead,i.e.,headmountedoscillators,andrelativemovement ofgraphitereflectorblockswithrespecttooneanotherwithinthecoolant.Thesedynamicbehaviorsare accountedforinthedesignofthereactoranditsinternals,toensurecontinuedfunctionalityduringand afteradesignbasisearthquake.Modelsareusedtounderstandfluidmigrationtendenciesconsidering thepebblebed,reflectorblocks,corebarrel,andotherreactorvesselinternalfeatures.Theinsights gainedfromtheanalysisofthesemodelsareusedtodesignthereactortopreventdamagetothevessel duringadesignbasisearthquake.Thereactorvessel,vesselinternals,andvesselattachmentssuchas theRCSSareclassifiedasSDC3perASCE4319SeismicDesignCriteriaforStructures,Systems,and ComponentsinNuclearFacilities(Reference2).Thereactorvesselwillalsobeprotectedfromthe failureofnearbynonsafetyrelatedSSCsduringadesignbasisearthquakebyseismicallymounting, physicallyseparating,orusingabarriertoprecludeadverseinteraction,andfromfailureofattached nonsafetyrelatedSSCs,suchasattachedpiping(e.g.,bydesignforpreferentialfailureofthenonsafety componentisawaythatdoesnotimpactthevessel).Thesefeaturesdemonstratecompliancewith PDC2.

Thereactorvesselcanaccommodateinternalandexternalstaticanddynamicloads.Thethermal expansionofthereactorvesselshellandbottomheadissupportedbythereactorvesselsupportsystem (RVSS)(seeSection4.7)duringreactorstartup,normaloperation,andpostulatedevents.Mechanical loadingsfromstaticweight,seismicload,andforcesfromthepebblebed,coolant,andcore componentsaretransferredtothevesselshell,tothebottomhead,andthentotheRVSS.Thelateral loadpathofthevesselsupportisdesignedtoprecludedamagetothedecayheatremovalsystemand ensurethevesselmaintainsitsintegrityandremainsinanuprightposition.Thedesignofthevessel shellresistshoopstressesfromthepressureinthedowncomerandsupportsthetransferofstaticand dynamicloadsbetweenthevesseltopheadandthevesselbottomheadtotheRVSS.Therearealsono pressurizedpipingsystemsinoraroundthereactorvessel,thusprecludingpipewhiphazards.Heavy loadconsiderationsareaddressedinSection9.8.4,CranesandRigging.Thesefeaturesdemonstrate compliancewithPDC4.

Corecoolingismaintainedthroughthedesignofthereactorvesselandthereactorvesselinternals.As describedinSection4.3.1.2,thevesselandvesselinternalsdefinethecoolantflowpath.Topreclude degradationtothevesselduetocorrosionofthestainlesssteel,thereflectorblocksandthevesselare baked(i.e.,heateduniformly)toremoveresidualmoisturepriortocomingintocontactwithcoolant.

KairosPowerHermesReactor Revision2433 PreliminarySafetyAnalysisReport ReactorDescription

Table4.32:LoadCombinationsfortheReactorVesselSystem ServiceLevel LoadCombination*

A D+L+To+Po+Ro B D+L+To+Po+Ro+Eo D+L+Ti+Pi+Ri+Eo C D+L+To+Po+Ro+Ess D+L+Ts+Ps+Rs+Ess D D+L+Ta+Pa+Ra+Wt D+L+Ta+Pa+Ra+Ess

  • Loadcombinationreferstothetypesofloadsconsideredactingsimultaneously.Applicationof loadfactorsandspecificdetailsofloadcombinationeffectsarepertheapplicabledesign standards.

LoadNomenclature:

D Deadloads L Liveloads To Thermalloadsduringstartup,normaloperating,orshutdownconditions Ti ThermalloadsduringServiceLevelBloadings Ta ThermalloadsduringServiceLevelDloadings Ts ThermalloadsduringServiceLevelCloadings Po Pressureloadsduringstartup,normaloperating,orshutdownconditions Pi PressureloadsduringServiceLevelBloadings Ps PressureloadsduringServiceLevelCloadings Pa PressureloadsduringServiceLevelDloadings Ro Pipereactionsduringstartup,normaloperating,orshutdownconditions Ri PipereactionsduringServiceLevelBloadings Ra PipereactionsduringServiceLevelDloadings Rs PipereactionsduringServiceLevelCloadings Eo Loadsgeneratedby1/3ofdesignbasisearthquake(DBEthedesignbasisearthquakeis alsothesafeshutdownearthquake[SSE])

Ess LoadsgeneratedbyDBESSE Wt Accidentalloadsduetomissileimpacteffects

KairosPowerHermesReactor Revision2438 Preliminary Safety AnalysisReport ReactorDescription

Table4.71: Load CombinationsfortheReactorVessel SupportSystem ServiceLevel Load Combination*

A D+L+To+Ro B D+L+To+Ro+Eo D+L+Ti+Ri+Eo C D+L+To+Ro+Ess D+L+Ts+Rs+Ess D D+L+Ta+Ra+Wt D+L+Ta+Ra+Ess

  • Loadcombinationrefers tothetypesofloadsconsidered actingsimultaneously.Applicationof loadfactorsandspecificdetailsofloadcombinationeffectsarepertheapplicabledesign standard.

Load Nomenclature:

D Deadloads L Liveloads To Thermalloadsduringstartup,normaloperating,orshutdownconditions Ti ThermalloadsduringServiceLevelBloadings Ta ThermalloadsduringServiceLevelDloadings

Ts ThermalloadsduringServiceLevelCloadings Ro Pipereactionsduringstartup,normaloperating,orshutdownconditions Ri PipereactionsduringServiceLevelBloadings Ra PipereactionsduringServiceLevelDloadings Rs PipereactionsduringServiceLevelCloadings Eo Loadsgeneratedby1/3 SSEofdesignbasisearthquake(DBE)

Ess LoadsgeneratedbySSEDBE Wt Accidentalloadsduetomissileimpacteffects

Kairos PowerHermesReactor Revision2466 PreliminarySafetyAnalysisReport InstrumentationandControls

PHTSthermalmanagement Controloftheheatrejectionsubsystem Primaryloopdraining,filling,andpipingmonitoring,includingPHTSexternalpiping ThepurposeofthePHTCSistocontrolthetransportofprimarycoolantthroughthePHTS,tomaintain theprimarycoolantinaliquidstate,tocontroltherejectionofheatfromthePHTS,andtomonitorthe inventoryofprimarycoolantinthePHTS.ThePHTCSmaintainstheparametersinthePHTSwithinthe normaloperatingenvelope.ThePHTCScontrolstheprimarysaltpump(PSP),theprimaryloopthermal managementsubsystem(PLTMS),andtheheatrejectionsubsystem.ThesensorsusedbythePHTCSare discussedinSection7.5.

ThePHTCSprovidescontrolsignalforthePSP(seeChapter5).Thecontrolsystemmanipulatesthe primarycoolantflowratebyvariablefrequencytomaintainPHTSparameterswithinthenormal operatingrange.ThePHTCSdoesnotprovideasafetyfunction;however,asdiscussedinSection7.3,the RPStripsthePSPonareactortrip,asaprotectionfeatureforthereactorsystemrelatedtothepump.

ThePHTCSmaintainstheprimarycoolantinliquidphasethroughoutthePHTStopreventlocalizedover orunderheating.ThecontrolsystemusestemperatureasinputtoprovidecontrolsignaltothePHTS auxiliaryheaters.

ThePHTCSprovidescontrolsandmonitoringofthecomponentsthatsupporttheoperationoftheheat rejectionsubsystem.

7.2.2 DesignBases ConsistentwithPrincipalDesignCriteria(PDC)13,thePCSisdesignedtomonitorvariablesandsystems overtheiranticipatedrangesfornormaloperation,andovertherangedefinedinpostulatedevents.

7.2.3 SystemEvaluation ThePCSisdesignedtomonitorplantparametersandmaintainsystemswithinnormaloperatingrange.

ThePCSisalsodesignedtocontrolplannedtransientsassociatedwithanticipatedoperational occurrencesandmaintainthereactorinashutdownstate.ThesefunctionsareconsistentwithPDC13.

ThePCSdoesnotperformasafetyrelatedfunction.Finally,thePCSisdesignedsothatitcannot interferewithRPSsabilitytoperformitssafetyfunctions;seeSection7.3formoreinformationabout theisolationoftheRPSfromthePCS.

ThePCSisadigitalsystemthatcontrolsthereactorpoweraboutapointsetbytheoperator.Thecontrol systemuseslinearaveragetemperatureandflowrateintheprimarysystemasvariableinputsto controlpowerlevelsothatitremainswithinthenormaloperatingenvelope.Thesystemdesignmeets theapplicableportionsInternationalElectrotechnicalCommission(IEC)standard61131forindustrial controllers(Reference1),andtheapplicableportionsofthecybersecuritystandardIEC62443 (Reference2).Table7.22listsotherstandardsappliedtothePCS.ApplicableportionsofIEEE1012 2017(Reference3)areusedforverificationandvalidationofPCScomponents,whichisconsistentwith thenonsafetyrelatedclassificationofthePCS.

ActioninthePCSisdesignedtoaccuratelyandreliablyprovidecontrolsignalforallmodesofnormal operation.ThePCSisalsodesignedtoprovidetimelycontrolsignals,withfurtheranalysisoftimeliness tobeprovidedinanapplicationfortheOperatingLicense.

KairosPowerHermesReactor 77 Revision2 PreliminarySafetyAnalysisReport InstrumentationandControls

7.3 REACTORPROTECTIONSYSTEM 7.3.1 Description TheRPSprovidesprotectionforreactoroperationsbyinitiatingsignalstomitigatetheconsequencesof postulatedeventsandtoensuresafeshutdown.TheRPSistheonlyportionoftheI&Csystemthatis safetyrelatedandthatiscreditedfortrippingthereactorandactuatingengineeredsafetyfeatures.The purposeoftheRPSistoactuateuponreceiptofatripsignalinresponsetooutofnormalconditionsand provideautomaticinitiatingsignalstoprotectionfunctions.Therearethreepossibletripsourcesthat cancausetheRPStoactuateandthreeprotectionfunctionsthatresultfromRPSactuation,shown belowinFigure7.31.Thethreepossibletripsourcesare:

Processvariablesreachorexceedspecifiedsetpoints,asmeasuredbyRPSsensors Manualinitiationfromthemaincontrolroomorremoteonsiteshutdownpanel Plantelectricpowerislost(withatimedelay)

ThethreeKPFHRprotectionfunctionsthatresultfromRPSactuationare:

ActuatetheRCSSthatinsertscontrolandshutdownelementsintothereactorcore InhibitactionsfromthePCSsothatitdoesnotinterferewiththefunctioningoftheRPS Ensureanactuationofthedecayheatremovalsystem(DHRS)thatpassivelyremovesheatfromthe PHTStotheatmosphere ActuationoftheRPStotripthereactorincludesseveralactuationsthatstopspecificnonsafetyrelated SSCs,normallycontrolledbyPCS,toensurethatthosenonsafetyrelatedSSCstodonotpreventa safetyrelatedSSCfromperformingitssafetyfunction.Thenonsafetyrelatedfunctionsthatare stoppedareshowninFigure7.117.31.RCSSelementwithdrawalisinhibitedafteralossofpower,to preventinadvertentpositivereactivityinsertionwhenpowerreturns(seealsoTable7.32).ThePSPis stoppedtomaintainFlibeinventoryinthecore.Theheatrejectionsubsystemblowerisstoppedto preventpotentialforcedairingressintothePHTSandinadvertentovercooling.Pebbleextractionand insertioninthePHSSisstoppedtopreventremovingpebblesfromthecoreintheeventofaPHSS extractionlinebreak.Finally,RTMSandPLTMSactuationsisareprohibitedtopreventachallengetothe heatremovalcapabilityoftheDHRS.Theseinhibitionsareaccomplishedthroughsafetyrelatedtrip devicesasshowninFigure7.11.

TheRPSisbuiltonalogicbasedplatformthatdoesnotutilizesoftwareormicroprocessorsfor operation.Itiscomposedoflogicimplementationusingdiscretecomponentsandfieldprogrammable gatearray(FPGA)technology.TheRPSisisolatedfromotherI&Csystems,includingthemaincontrol roomandtheremoteonsiteshutdownpanel,usingsafetyrelatedisolationhardware.Isolationis achievedatthepointofsignalgenerationeitherthroughfeaturesbuiltintothehardwareplatformor throughseparateisolationdevices.TheRPSincludesthefollowingsafetyrelated(exceptasnoted otherwise)elements:

Separatechannelsofsensorelectronicsandinputdevices Redundantandseparategroupsofsignalconditioning Redundantandseparategroupsoftripdetermination Manualreactortripswitchesinthemaincontrolroom(switchesarenonsafetyrelated)

Safetyrelatedcomponentstoprovideelectricalisolationfromthenonsafetyrelatedhighlyreliable DCpowersystempowersupply Multiplereactortripdevicesandassociatedcabling(cablingisnonsafetyrelated)

RPSisolationhardware Twodivisionsofreactortripsystem(RTS)votingandactuationequipment

KairosPowerHermesReactor 712 Revision2

PreliminarySafetyAnalysisReport AuxiliarySystems

removethedecayheatproducedbyindividualpebblesduringtheirtransitthroughthePHSS.Also, oxidationassociatedwithairormoistureingressintothePHSSisnegligibleforpebblesat temperaturesexperiencedinthesystem.Thesystemalsominimizespebblewear.ThelimitingPHSS malfunctionevent,whichisdiscussedinSection13.1.5,doesnotcausetemperatureexcursions, oxidation,ormechanicalstressesontheTRISOparticles.Therefore,containmentandconfinement ofradioactivityismaintainedbytheTRISOparticles.

FuelandmoderatorpebblesaremanufacturedtospecificationsasdescribedinSection4.2.1and arebakedpriortointroductiontothereactortoremoveresidualmoisture.Afterthepebblesexit thecore,theinspectionsystem,asdescribedinSection9.3.1.5,isusedtoinspectthephysical conditionofthepebbleandmeasurethefuelburnup.Theinspectionisperformedtoidentify abnormalwear,cracking,andmissingsurfacesduetopebblechipping.Gammaspectrometryisalso usedtodeterminetheburnupbymeasuringgammarayactivityfromfissionproducts.Pebblesator approachingtheburnuplimitaresenttostorageinlieuofbeingreturnedtothecore.Pebblesthat showindicationsofwear,cracking,ormissingsurfacesarealsoremovedfromserviceandplaced intostorage.

ThePHSSisadequatelyshieldedtolimitworkerdose,inaccordancewith10CFR20andthe radiationprotectionprogram,asdescribedinChapter11.

ThestoragepartofPHSSisdesignedtotransferexvesseldecayheattotheCCWSandtheSFCSfrom afullcoreoffloadandpebbleoffloadduetonormaloperation.ThePHSSisdesignedtoensure decayheatloadsfrompebblesinthespentfuelstoragepoolarepassivelycooledbythewaterof thepoolandspacingofthestoragecanistersintheeventofalossofpower.Thecanistersinthe storagebayarecooledduringpostulatedeventsbynaturalconvectionduetothespacingwhich allowssufficientairflow.

PDC62requirescriticalityinafuelstorageandhandlingsystembepreventedbyphysicalsystemsor processes,preferablybyuseofgeometricallysafeconfigurations.Thedesignfeatureswhichaddress PDC62forthePHSSaredescribedbelow:

ThePHSSisdesignedtoprecludecriticalitybymaintainingasubcriticalgeometryduringhandling.

ThePHSSremovespebblesfromthecoreataratethatprohibitstheformationofacritical configurationoffuelpebblesoutsidethereactor.IntheeventofaPHSSlinebreach,thenumberof spilledpebblesislimitedandacriticalgeometryisprecludedbydesign.Theoffheadconveyance, processing,inspection,pebbleinsertion,storageareas,andinertgasboundarymaintainaninertgas environmentprecludingmoistureintrusionintothosehandlingareas,furtherreducingtheriskof criticality.Fuelhandlingequipmentmaintainsasubcriticalgeometryviaphysicalconstraintsand/or systeminterlocks.

Thespentfuelstorageareaconsistsofawatercooledpool,anaircooledstoragebay,seismic restraintsmaintainingthecanistersphysicallocation(i.e.,spacing),andthesurroundingconcrete structure.Thepreliminarycriticalityanalysisdeterminingthespacingrequirementsforeachcanister inthespentfuelstorageareaconservativelyassumesthestoragecontainersarenotfloodedand completelysubmergedunderwater.

Thetransportconfiguration,inwhichastoragecanisterisbeingmovedusingacanistertransporter toeitherthestoragebayorthefullcoreoffloadsystem(i.e.,fuelpool),willbeanalyzedtoensurea subcriticalgeometryismaintained.Asummaryofthecriticalityanalysesconfirmingthesystem designmaintainsageometricallysafeconfigurationwillbeprovidedwiththeapplicationforan OperatingLicense.

PDC63requiresdetectionofconditionsthatcouldresultinexcessiveradiationlevelsinhandlingareas andameansbywhichtoinitiateappropriatesafetyactions.ThePHSSisdesignedtoassurethat

KairosPowerHermesReactor 929 Revision2 PreliminarySafetyAnalysisReport AuxiliarySystems

9.8 OTHERAUXILIARYSYSTEMS Thefollowingsubsectionsprovidedescriptionsandfunctionalrequirementsofotherauxiliarysystems.

Theseotherauxiliarysystemsinclude:

Remotemaintenanceandinspectionsystem Spentfuelcoolingsystem Compressedairsystem Cranesandrigging Auxiliarysiteservices Theseauxiliarysystemsarenotsafetyrelatednoraretheycreditedwithperformingasafetyfunction.

9.8.1 RemoteMaintenanceandInspectionSystem Theremotemaintenanceandinspectionsystem(RMIS)providesthecapabilitytoremotelyhandle componentsinthereactorsystem,PHTS,andPHSS.Thesystemalsoprovidesthecapabilitytoconduct inspectionsofhazardousequipment.ComponentsoftheRMISincluderemotemanipulators,tooling, cameras,monitors,cranesandrigging.Thesystemislocatedinthereactorbuildingandcontainstooling tosupportthefollowingmaintenanceactivities:

Disassembleflangesandsubassemblies Removesubassemblies ClearfuelandresidualcoolantbeforeremovalofSSCsformaintenance Transportofequipmenttohotmaintenancecells(viauseofshieldedcasks)

Activitiesperformedinstandalonehotcells Useofthroughwallelectromechanicalmanipulatorsforhotcells Useofcranesforhotcellandpostirradiationexaminationfacilities.

Thesystemisdesignedinaccordancewithlocalbuildingcodes.Thesystemdoesnotperformsafety relatedfunctionsandisdesignedsothatitcannotinterferewithasafetysystemsabilitytoperforma safetyfunction.Theremotemanipulationcapabilitiesprovidedbythesystemfacilitatelimiting personneloccupationalexposurestobelow10CFRPart20limitsduringmaintenanceofthereactor system,PHTS,andPHSS.

Consistentwith10CFR20.1406,theremotemaintenanceandinspectionsystemisdesigned,tothe extentpracticable,tominimizecontaminationofthefacilityandtheenvironment,andtofacilitate eventualdecommissioning.

PortionsoftheRMISthatmaycrosstheisolationmoatincludeflexibledesignfeaturestoaccommodate maximumdesigndisplacementsfrompostulatedseismicevents.Thedesignfeaturesfunctionwouldbe topreventthedamagefromtheSSCsintheRMISfromaffectingasafetyrelatedSSC'sabilitytoperform asafetyfunction.SpecificdesignfeaturesandtheSSCstowhichtheyareapplied,willbeprovidedinthe operatinglicenseapplication.

9.8.2 SpentFuelCoolingSystem TheSFCSprovidesforcedaircoolingforspentfuelstoragecanistersinthestoragebayofthePHSS(see Section9.3)andrecirculateswaterinthespentfuelpool.Thesystemissizedtocoolstoredspentfuel andmoderatorpebblesgeneratedduringthe104yearlifetimeofthereactor.TheSFCSconsistsoffans andpipingthatremoveheatduringnormaloperation,tomaintaindesiredoperationaltemperaturesin thestoragebay.TemperaturesinandaroundtheSSCsservedbytheSFCS,includingthestorage

KairosPowerHermesReactor 943 Revision2 PreliminarySafetyAnalysisReport AccidentAnalysis

evaluatethesurrogatefiguresofmeritthatensuretheeventconsequencesareboundedbytheMHA areprovidedinReference2.

13.1.5.1 InitialConditionsAssumptions ConservativeinitialvaluesareassumedfortheamountsofFlibe,tritium,andgraphitedustavailableto bemobilizedwithinthePHSS.

Theeventinitiatorisassumedtobeabreakinafueltransferlineduringextraction,allowingpebblesto spilloutofthesystemandontothefloor.

13.1.5.2 StructuresSystemsandComponentsMitigationAssumptions ThissectiondescribestheSSCsperformingafunctiontomitigatetheconsequencesoftheevent.

TheRPSiscreditedwithinitiatingaPHSStrip.ThePHSStripstopspebbleextractionandinsertion followingthereactortriptopreventadditionalpebblesspillingoutofthebreakandtoprecludeany damagetopebblesfromfaultsduringtheevent.ThedesignbasesoftheRPSarediscussedinSection 7.3.TheRPSdetectionandactuationcapabilitiesareautomaticanddonotrelyonmanualactionto performthesefunctions.

TheTRISOfuellayersandtheFlibearecreditedwiththeradionuclideretentionpropertiesdescribedin Reference1.Thestructuralintegrityofthefuelpebblesiscreditedwhenthespilledpebbleshitthefloor tomaintaintheTRISOconfinementfunction.Thelowfissileinventoryofthepebblesprecludescriticality concernsofthespilledpebbles.

13.1.5.3 TransientAssumptions Thissectiondescribestheassumptionsassociatedwiththetransientanditseffectsonthesurrogate figuresofmerit.

Thepostulatedeventanalysisassumesconservativetripandactuationdelaystoaccountforuncertainty inthesignaltimeassociatedwiththeRPS.

Theamountofheatinthepebblesisconservativelymodeled.

ThekeyfiguresofmeritforthiseventandtheacceptancecriteriaareprovidedinTable13.11.

Asafestateisestablishedwhen:

Themovementofpebblesoutsideofthecorehasstoppedandcriticalitysafetyisassured.

Decayheatisbeingremovedfrompebblesoutsideofthecoreandlongtermcoolingisassured, wherefigureofmerittemperaturesaresteadilydecreasing.

13.1.6 RadioactiveReleasefromaSubsystemorComponent Aradioactivereleasefromasubsystemorcomponentcouldresultfromthefailureofasystemor componentcontainingradioactivematerial.However,thelimitingeventforthiscategoryisassumedto beaseismiceventthatresultsinthefailureofallsystemscontainingradioactivematerialthatarenot qualifiedtomaintainstructuralintegrityinasafeshutdowndesignbasisearthquake.Theonlyfigureof meritforthiseventistheamountofradioactivematerialcontainedinsubsystemsandcomponents.To ensurethatthiseventgroupisboundedbytheMHA,thereisadesignrequirementontheamountof MARforreleaseinsubsystemsandcomponentstoremainbelowtheamountofMARforrelease assumedintheMHA.Thesystemsexpectedtoaccumulateradionuclidesasafunctionofoperation include:

KairosPowerHermesReactor 1311 Revision2 PreliminarySafetyAnalysisReport TechnicalSpecifications

Table14.11:ProposedVariablesandConditionsforTechnicalSpecifications

Section SectionName LCOorCondition Basis

2.0 SafetyLimits(SL)andLimitingSafetySystemSettings(LSSS)

SafetyLimitsarethoselimitsonprocessvariablesthatarenecessarytoreasonably protecttheintegrityofcertainphysicalbarriersthatarecreditedtoprecludeapotential uncontrolledreleaseofradioactivity.

LimitingSafetySystemSettingsaresettingsforautomaticprotectivedevicesrelatedto thosevariableshavingsignificantsafetyfunctions.Thesesettingsensurethatautomatic protectiveactionwillcorrecttheabnormalsituationbeforeaSafetyLimitisexceeded.

ThisTableconsistsoftheproposedsubjectsofSafetyLimitsandLimitingSafetySystem Settings.Theseareprovidedbelow.

2.1 SLThefueltemperaturesshallnotThemaximumfueltemperatures exceedanupperbound SafetyLimitisestablishedtoensure operatingrangeunderany fuelintegritybasedontemperatures operatingconditions. assumedinthesafetyanalysis.

2.1 SL ThereactorvesselsurfaceThemaximumreactorvesselsurface temperaturesshallnotexceed temperatureSafetyLimitisthe anupperboundtemperature maximumtemperaturethatcanbe underanyconditionof permittedwithconfidencethatvessel operation. integritywillbemaintained.

2.2 LSSS ThecoreexitreactorcoolantLimitingthemaximumcoreexit temperature(s)shallnot coolanttemperaturewillensurethat exceedanupperbound theSafetyLimitsarenotexceededand temperatureunderany thatthereactorwilltrippriorto conditionofoperation. reachingaSafetyLimit.

2.2 LSSS ThecoolantlevelshallnotfallLimitingthecoolantlowlevelwill belowalowerboundlimit ensurethatadequatecorecoolingis underanyconditionof availablesothattheSafetyLimitsare operation. notexceeded.

2.2 LSSS TherateoffluxtripfunctionLimitingtherateofpower/flux shallnotexceedanupper increasewillensurethatthereactor boundlimitasspecifiedinthe willtrippriortochallengingthe safetyanalysis. integrityoffuel(oralimitationsetin fuelperformancemethodology).

KairosPowerHermesReactor 143 Revision2

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