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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Site: Hermes File:Kairos Power icon.png
Issue date: 04/25/2023
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Kairos Power
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Office of Nuclear Reactor Regulation
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KP-NRC-2304-005
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KP-NRC-2304-005 Changes to Hermes PSAR Chapters 2, 3, 4, 7, 8, 9, 13, and 14 (Non-Proprietary)

Preliminary Safety Analysis Report Site Characteristics Kairos Power Hermes Reactor 2-9 Revision 2 Figure 2.1-2: Prominent Features in Site Area

Preliminary Safety Analysis Report Site Characteristics Kairos Power Hermes Reactor 2-10 Revision 2 Source: Reference 1

Preliminary Safety Analysis Report Site Characteristics Kairos Power Hermes Reactor 2-12 Revision 2 Figure 2.1-3: Project Site Area and Zones Associated with the Facility

Preliminary Safety Analysis Report Site Characteristics Kairos Power Hermes Reactor 2-13 Revision 2 Source: Reference 1

PreliminarySafetyAnalysisReport

DesignofStructures,Systems,andComponents

KairosPowerHermesReactor 329 Revision2 Table3.51:LoadCombinationsfortheSafetyRelatedPortionoftheReactorBuilding ServiceLevelLoad Category LoadCombination*

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

PreliminarySafetyAnalysisReport

DesignofStructures,Systems,andComponents

KairosPowerHermesReactor 333 Revision2 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.

PreliminarySafetyAnalysisReport

ReactorDescription

KairosPowerHermesReactor

Revision2 432 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.

PreliminarySafetyAnalysisReport

ReactorDescription

KairosPowerHermesReactor

Revision2 433 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.

PreliminarySafetyAnalysisReport

ReactorDescription

KairosPowerHermesReactor

Revision2 438 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

PreliminarySafetyAnalysisReport ReactorDescription KairosPowerHermesReactor

Revision2 466 Table4.71:LoadCombinationsfortheReactorVesselSupportSystem ServiceLevel LoadCombination*

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

  • Loadcombinationreferstothetypesofloadsconsideredactingsimultaneously.Applicationof loadfactorsandspecificdetailsofloadcombinationeffectsarepertheapplicabledesign standard.

LoadNomenclature:

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 Loadsgeneratedby1/3SSEofdesignbasisearthquake(DBE)

Ess LoadsgeneratedbySSEDBE Wt Accidentalloadsduetomissileimpacteffects

PreliminarySafetyAnalysisReport

InstrumentationandControls

KairosPowerHermesReactor 77 Revision2 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.

PreliminarySafetyAnalysisReport

InstrumentationandControls

KairosPowerHermesReactor 712 Revision2 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

PreliminarySafetyAnalysisReport

InstrumentationandControls

KairosPowerHermesReactor 720 Revision2 Figure7.31:ReactorProtectionSystemTripLogicSchematic

PreliminarySafetyAnalysisReport

InstrumentationandControls

KairosPowerHermesReactor 721 Revision2

PreliminarySafetyAnalysisReport

ElectricalPowerSystems

KairosPowerHermesReactor 82 Revision2 Figure8.11:ElectricalConfigurationDiagram

PreliminarySafetyAnalysisReport

ElectricalPowerSystems

KairosPowerHermesReactor 83 Revision2

PreliminarySafetyAnalysisReport

AuxiliarySystems

KairosPowerHermesReactor 929 Revision2 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

PreliminarySafetyAnalysisReport

AuxiliarySystems

KairosPowerHermesReactor 943 Revision2 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

PreliminarySafetyAnalysisReport

AccidentAnalysis

KairosPowerHermesReactor 1311 Revision2 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:

PreliminarySafetyAnalysisReport

TechnicalSpecifications

KairosPowerHermesReactor 143 Revision2 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 SL Thefueltemperaturesshallnot exceedanupperbound operatingrangeunderany operatingconditions.

Themaximumfueltemperatures SafetyLimitisestablishedtoensure fuelintegritybasedontemperatures assumedinthesafetyanalysis.

2.1 SL Thereactorvesselsurface temperaturesshallnotexceed anupperboundtemperature underanyconditionof operation.

Themaximumreactorvesselsurface temperatureSafetyLimitisthe maximumtemperaturethatcanbe permittedwithconfidencethatvessel integritywillbemaintained.

2.2 LSSS Thecoreexitreactorcoolant temperature(s)shallnot exceedanupperbound temperatureunderany conditionofoperation.

Limitingthemaximumcoreexit coolanttemperaturewillensurethat theSafetyLimitsarenotexceededand thatthereactorwilltrippriorto reachingaSafetyLimit.

2.2 LSSS Thecoolantlevelshallnotfall belowalowerboundlimit underanyconditionof operation.

Limitingthecoolantlowlevelwill ensurethatadequatecorecoolingis availablesothattheSafetyLimitsare notexceeded.

2.2 LSSS Therateoffluxtripfunction shallnotexceedanupper boundlimitasspecifiedinthe safetyanalysis.

Limitingtherateofpower/flux increasewillensurethatthereactor willtrippriortochallengingthe integrityoffuel(oralimitationsetin fuelperformancemethodology).

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