ML22069B099

Enclosure 1: Kairos Power Response to NRC Question 3.2-1, 3.2-3, 3.2-4, and 3.5-1

ML22069B099
Person / Time
Site:	Hermes File:Kairos Power icon.png
Issue date:	03/10/2022
From:	Kairos Power
To:	Office of Nuclear Reactor Regulation
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ML22069B097	List: ML22069B099
References
KP-NRC-2203-004
Download: ML22069B099 (9)

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Enclosure1 KairosPowerResponsetoNRCQuestion3.21,3.23,3.24,and3.51 (NonProprietary)

QuestionNumber:3.21 Page1of2

Section3.2.3.2ofthePSARstatesthatthemaximumhurricanewindspeed(V)istakenfromRG 1.221.InthePSARthisvalueisidentifiedas130mph.ReadingFigure2inRG1.221itappearsV shouldbe140mph.Pleaseexplainhowitwasdeterminedthat130mphwasthepropervaluein accordancewithRG1.221.

KairosPowerResponse:

Figure1(attached)showsthelocationoftheHermessitesuperimposedonFigure2fromRG1.221, DesignBasisHurricaneWindspeedsfortheEasternGulfofMexicoandSoutheasternAtlanticU.S.

CoastlineRepresentingExceedanceProbabilitiesof107perYear.Valuesarenominal3secondgust windspeedsinmilesperhour(meterspersecond)at33ft(10m)abovegroundoveropenterrain (reproducedfromNUREG/CR7005).The130mphlinefromRG1.221,Figure2,isalmostdirectly abovetheHermessite.ParagraphC.1ofRG1.221statesthat[l]inearinterpolationforsiteslocated betweentwowindcontourlinesispermitted.Linearinterpolationwouldchangethehurricane windspeedbyabout1mph,whichwouldnotaffecttheresultsofthestructuralanalysisordesign.

Forthisreason,KairosPoweraffirmsthatitisreasonabletouse130mphasthemaximumhurricane windspeed.

ImpactonLicensingDocument:

ThisresponsehasnoimpactonthecontentoftheHermesNonPowerReactorPreliminarySafety AnalysisReport.

References:

1.RegulatoryGuide1.221,DesignBasisHurricaneandHurricaneMissilesforNuclearPower Plants,Revision0,October2011

Page2of2

Figure1.LocationoftheHermesSiteSuperimposedonRG1.221,Figure2

QuestionNumber:3.23 Page1of1

PSARSection3.2.4.2liststhegroundsnowload,pg,inEq.3.22as10poundspersquarefoot(psf) andnotesthatistakenfromFig.71ofAmericanSocietyofCivilEngineers(ASCE)710.Section7.2 ofASCE710notesthatpgisbasedona50yearrecurrenceinterval.PreliminarySafetyAnalysis Report(PSAR)Section2.3.1.11notesthatthevalueof10psfmustbeadjustedbyafactorof1.22to determinethe100yearreturnvalueof12.2psf.PSAR2.3.1.11furthernotesthatthenormalwinter precipitationeventatthesiteisdeterminedtobe21.9psf.Explainwhy10psfwastakenasthe groundsnowloadinsteadof12.2psfor21.9psf.

KairosPowerResponse:

KairosPowerwillchangethegroundsnowloadinSection3.2.4.2from10psfto21.9psffor consistencywithSection2.3.1.11.

ImpactonLicensingDocument:

ThisresponseimpactsSections3.2.4.2oftheHermesNonPowerReactorPreliminarySafetyAnalysis Report.Amarkupoftheaffectedsectionsisprovidedwiththisresponse.

References:

None

QuestionNumber:3.24 Page1of1

PSARSection3.2.4ThereisnodiscussionofrainonsnowsurchargeloadsasdiscussedinASCE7 10Section7.10.Explainhowtherainonsnowsurchargeisaddressedorwhyitdoesnotapply.

KairosPowerResponse:

KairosPowerintendstoapplyASCE710concerningrainonsnowsurchargeloadsifsuchloads applytothefinalroofdesign.KairosPowerwilladdcontentinSection3.2.4.2statingthattheroof designwillbeconsistentwithASCE710,includingSection7.10ifapplicable.

ImpactonLicensingDocument:

ThisresponseimpactsSection3.2.4.2oftheHermesNonPowerReactorPreliminarySafetyAnalysis Report.Amarkupoftheaffectedsectionsisprovidedwiththisresponse.

References:

None

Page1of1 QuestionNumber:3.5-1 PSARSection3.5.3.2.2explainshowsafetyrelatedSSCswillbeprotectedfrominternalfloodingdue tofireprotection;however,thereisnodiscussionofhowSSCswillbeprotectedfromtheactuation ofthefireprotectionsystem.ExplainhowsafetyrelatedSSCswillbeprotectedfromfireprotection water.

KairosPowerResponse:

KairosPowersintentwasthatsafetyrelatedstructures,systems,andcomponentswouldbe protectedbothfromactuationofthefireprotectionsystem(i.e.,spray)andfromfireprotection wateronthefloor(i.e.,pooling).ToclarifythisinthePSAR,KairosPowerwilltoaddcontentto Section3.5.3.2.2statingthatintent.

ImpactonLicensingDocument:

ThisresponseimpactsSection3.5.3.2.2oftheHermesNonPowerReactorPreliminarySafety AnalysisReport.Amarkupoftheaffectedsectionsisprovidedwiththisresponse.

References:

None

PreliminarySafetyAnalysisReport DesignofStructures,Systems,andComponents KairosPowerHermesReactor 314 Revision0 3.2.4.1 ApplicableDesignParameters BasedonRiskCategoryIVcharacterization(SeeSection3.2.1.1)andsitelocation,Chapters1and7of ASCE/SEI710providesnowloaddesignparameterstobeappliedtothesafetyrelatedportionsofthe ReactorBuilding.

3.2.4.2 DeterminationofAppliedForces Theslopedroof(balanced)snowloadiscalculatedbyEquation3.23asderivedfromASCE/SEI710, Section7.3andSection7.4usingthegroundsnowloadspecifiedinSection2.3.1.11.

ps=0.7CsCeCtIspg (Equation3.22)

Where, Cs=roofslopefactorasdeterminedbySections7.4.1throughSection7.4.4ofASCE/SEI7 10correspondingtothegeometryoftheroof Ce=exposurefactorasdeterminedbyTable72ofASCE/SEI710equalto1.0 Ct=thermalfactorasdeterminedbyTable73ofASCE/SEI710equalto1.0 Is=importancefactorasdeterminedbyTable1.51ofASCE/SEI710and1.52of ASCE/SEI710equalto1.2 pg=groundsnowloadassetforthinFigure71ofASCE/SEI710consistentwithSection 2.3.1.11equalto1021.9psf UnbalancedsnowloadsontheceilingofthesafetyrelatedportionoftheReactorBuildingare determinedinaccordancewithSection7.6ofASCE/SEI710.Thedesignsnowdriftloadsaredetermined inaccordancewithSection7.7ofASCE/SEI710.Ifapplicabletotheroofdesign,rainonsnow surchargeloadsaredeterminedinaccordancewithSection7.10ofASCE/SEI710.

3.5-1 References

1. AmericanSocietyofCivilEngineers,SeismicEngineeringInstitute,ASCE/SEI710,MinimumDesign LoadsforBuildingsandOtherStructures. 2010.

PreliminarySafetyAnalysisReport DesignofStructures,Systems,andComponents KairosPowerHermesReactor 324 Revision0

Thefacilityisapassivelydrysitewithrespecttoexternalfloodinghazards.Section3.3describesthatin thePMFevent,therearenoloadsonthesafetyrelatedportionoftheReactorBuildingthatisabove grade.Thebasementcontainingtheseismicisolatorunitsisabout20feetbelowgrade.Thesafety relatedportionoftheReactorBuildingisdesignedtowithstandbuoyantforcesandgroundwater associatedwiththePMF.

NoSSCslocatedinthebasementarecreditedtomitigatetheeffectsofapostulatedexternalflood event.ThebasematofthesafetyrelatedportionoftheReactorBuilding,whichissupportedbythebase isolators,asdiscussedinSection3.5.1,isatgradelevelandnosafetyrelatedSSCsinthesafetyrelated portionofthereactorbuildingarebelowthatbasematelevation.Therefore,PDC2ismetforPMF eventsbasedonthelocationabovegradelevelofallsafetyrelatedSSCsthatarecreditedtomitigate theeffectsofapostulatedexternalflood.

Althoughtheydonotperformasafetyfunctiontomitigatetheadverseeffectsofapostulatedexternal floodevent,theseismicisolatorunitsareonelevatedpedestalsabovethefoundationslab.Thebase isolationbasementisareinforcedconcretesafetyrelatedstructurewiththefollowingfeatures:

Waterstopsareprovidedinconstructionjointsbelowfloodlevel.

Externalsurfacesexposedtofloodlevelhavewaterproofcoating.

Furthermore,thesafetyrelatedportionoftheReactorBuildingisareinforcedconcretestructure designedtomeetACI3492013.ACI3492013isspecifictothedesignofsafetyrelatednuclear structuresandhasbuiltinmargin.ACI349isusedtodesignastructurethatcanwithstandthe postulatedexternalfloodingwaterloadsfromSection3.3.Withrespecttobuoyantforcesfroma postulatedexternalfloodeventonthebasementareaofthesafetyrelatedportionoftheReactor Building,basedonafloodlevelnohigherthangrade,theweightofthebuildingoffsetsthepotential buoyantforcesonthebasement.BydesigninginaccordancewithACI3492013,thesafetyrelated portionoftheReactorBuildingsatisfiesPDC2fordesignbasisloadsfromexternalfloodingasdiscussed inSection3.3.

Finally,consistentwithPDC2,gradinganddrainageonthesiteprecludeloadsfromprecipitation affectingthesafetyrelatedportionoftheReactorBuilding.Specificgradinganddrainagefeatureswill bedescribedintheapplicationforanOperatingLicense.

3.5.3.2.2 InternalFloodandSprayDesignFeatures ThissectiondescribesthedesignfeaturesthatsatisfyPDC2withrespecttoprotectionfrominternal floodingforsafetyrelatedSSCs.SafetyrelatedSSCsthatarevulnerabletowaterdamagefrominternal sprayorfloodsareelevatedabovethefloorandshielded,orotherwiseprotected,frompotentialspray.

Waterisdirectedawayfromenclosuresforsafetyrelatedequipmentandslopedfloorsandcurbs precludewaterentryintotheseareas.Wherethereisapotentialforpebblestobeonaslopedor curbedfloor,featurespreventpebblesfromrollingsothatpebblesonthefloorofthesafetyrelated portionoftheReactorBuildingmaintainageometricallysafeconfigurationforcriticality.

InternalfloodingorsprayinginthesafetyrelatedportionoftheReactorBuildinghasthreepotential sources:watersystemwithSSCslocatedinthesafetyrelatedportionofthereactorbuilding,water systemSSCslocatedinthenonsafetyrelatedportionoftheReactorBuilding,andfireprotectionwater.

ForwatersystemswithSSCslocatedinthesafetyrelatedportionoftheReactorBuilding,theamountof waterislimitedbydesign.Themaximumflowrateandthevolumeofwateravailableforreleasefroma breakinthesafetyrelatedportionoftheReactorBuilding,isusedtodeterminetheeffectofinternal floodingorsprayingonsafetyrelatedequipment.Thequantityandflowrateofwaterislimitedtothe

PreliminarySafetyAnalysisReport DesignofStructures,Systems,andComponents KairosPowerHermesReactor 325 Revision0

gravitydrivenpressureheadabovethebreaklocation.Apumptripinawatersystemisassumedto terminatetheflowandaconstrainedamountoffluidisassumedtospillintothefacility.

ForwatersourcesexternaltothesafetyrelatedportionoftheReactorBuilding(e.g.,firewater),

automaticoramanualterminationofflowwillbespecifiedintheapplicationfortheOperatingLicense.

ThefireprotectionsystemimplementsNFPA801,StandardforFireProtectionforFacilitiesHandling RadioactiveMaterials(Reference3).Thewatercollectionduetothepotentialfailureofthefire protectionpipingisboundedbythetotaldischargefromtheoperationofthefireprotectionsystem.

Thewatercollectionsystemcanaccommodatethetotalfirefightingwatervolume.Slopedfloorsand curbspreventfireprotectionwaterfromdrainingintotheradioactivewastehandlingsystemdrains.

Sprayshields,orsimilar,preventfireprotectionwaterfromsprayingsafetyrelatedSSCsthatwouldbe sensitivetowaterspray.

SafetyrelatedSSCsareprotectedfromspilledFlibeandFlibebearingcomponentsarealsoprotected fromwatertopreventinteractionbetweenwaterandFlibe.Featuresincludesteelliners,catchpansor troughs,orsimilardesignsolutions.

Thosepipes,vessels,andtankswiththepotentialtofloodorspraysafetyrelatedportionsofthe ReactorBuildingareseismicallyqualifiedinaccordancewithlocalbuildingcodeandconsistentwiththe seismicdesigncategorybasedontheSSCssafetyclassification.Thereisnohighenergypipinginthe safetyrelatedportionoftheReactorBuilding,thereforeahighenergybreakisnotconsidered.

Furtherinformationontheanalysisoftheimpactsofinternalfloodingandsprayingwillbeprovided withtheapplicationforanOperatingLicense.

3.5.3.3 ConformancewithPDC2forEarthquakes Section3.4discussedthedesignbasisearthquakecharacteristicsthataretheinputforthedesignofthe safetyrelatedportionoftheReactorBuilding.Thesafetyrelatedportionofthereactorbuildingis designedconsistentwiththegradedapproachinASCE4319(Reference4).SeeSection3.4formore informationaboutthegradedapproach.BymeetingASCE4319,thesafetyrelatedportionofthe ReactorBuildingprovidesprotectionforsafetyrelatedSSCsfromdesignbasisearthquakes,consistent withPDC2.

ThesafetyrelatedportionoftheReactorBuildingusesbaseisolationasdescribedinSection3.5.1.The seismicisolationsystemisdesignedtolimittheloadsfromdesignbasisearthquakesonsafetyrelated SSC,consistentwithPDC2.

3.5.3.3.1 SeismicDesignoftheSafetyRelatedPortionoftheReactorBuilding SeismicqualificationofSDC3structuresfollowstherequirementsofSection5ofASCE4319.Structural demandsaredeterminedbasedontheresultsoftheresponseanalysisoutlinedinSection3.4.1.In additiontotheseismiceffects,theeffectsfromgravity,operatingloads,andotherconcurrentloading (e.g.snow)areconsideredonthestructuraldemands.

Seismicacceptanceischeckedforbothstrengthanddisplacementbasedcriteriasummarizedin Section5.2.2and5.2.3ofASCE4319,respectively,fortheapplicablelimitstates.Strengthbased qualificationofstructuralelementsutilize,whenappropriate,theinelasticenergyabsorptionfactors discussedinSection5.1.3ofASCE4319andsummarizedinTable51ofASCE4319.Allowabledriftand rotationlimitsarebasedonthediscussioninSection5.2.3ofASCE4319andsummarizedinTables52 and53ofASCE4319.