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#REDIRECT [[GNRO-2016/00053, Mitigating Strategies Assessment (MSA) for Flooding Submittal]]
| number = ML16365A194
| issue date = 12/30/2016
| title = Grand Gulf, Unit 1 - Mitigating Strategies Assessment (MSA) for Flooding Submittal
| author name = Fallacara V
| author affiliation = Entergy Operations, Inc
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000416
| license number = NPF-029
| contact person =
| case reference number = CAC MF1102, EA-12-049, GNRO-2016/00053
| document type = Letter, Report, Miscellaneous
| page count = 16
| project = CAC:MF1102
| stage = Other
}}
 
=Text=
{{#Wiki_filter:*GNRO-2016/00053December30,2016U.S.NuclearRegulatoryCommissionAttn:DocumentControlDeskWashington,DC20555-0001EntergyOperations,Inc.P.o.Box756PortGibson,MS39150VincentFallacaraVicePresident,OperationsGrandGulfNuclearStationTel.(601)437-7500
 
==SUBJECT:==
MitigatingStrategiesAssessment(MSA)forFloodingSubmittalGrandGulfNuclearStation,Unit1DocketNo.50-416LicenseNo.NPF-29
 
==REFERENCES:==
1.NRClettertoEntergy,RFIPursuanttoTitle10oftheCodeofFederalRegulations50.54(f)RegardingRecommendations2.1,2.3,and9.3oftheNTTFReviewofInsightsfromtheFukushimaDai-ichiAccident,datedMarch12,2012(GNRI-2012/00059)(ML12053A340)2.EntergylettertoNRC,ResponsetoMarch12,2012,RequestforInformation,Enclosure2,Recommendation2.1,Flooding,RequiredResponse1,IntegratedAssessmentApproach,datedJanuary29,2013(GNRO-2013/00002)(ML13029A627).3.EntergylettertoNRC,RequiredResponse2forNear-TermTaskForceRecommendation2.1:Flooding-HazardReevaluationReport,datedMarch11,2013(GNRO-2013/00020)(ML13071A457)4.EntergylettertoNRC,GrandGulfNuclearStationRequestforAdditionalInformationRegardingFloodingHazard,datedDecember11,2013,datedJanuary9,2014(GNRO-2014/00005)(ML14014A277)5.NRCStaffRequirementsMemorandatoCOMSECY-14-0037,"IntegrationofMitigatingStrategiesforBeyond-Design-BasisExternalEventsandtheReevaluationofFloodingHazards",datedMarch30,2015(ML15089A236)6.NRCLetter,CoordinationofRequestsforInformationRegardingFloodingHazardReevaluationsandMitigatingStrategiesforBeyond-Design-BasisExternalEvents,datedSeptember1,2015(ML15174A257)7.NuclearEnergyInstitute(NEI),ReportNE112-06[Rev2J,DiverseandFlexibleCopingStrategies(FLEX)ImplementationGuide,datedDecember2015(ML15348A015)8.NRCLettertoEntergy,GrandGulfNuclearStation,Unit1,SupplementtoStaffAssessmentofResponseto10CFR50.54(f)InformationRequest-Flood-CausingMechanismReevaluation,datedDecember4,2015(CACNO.MF1102)
GNRO-2016/00053Page2of39.U.S.NuclearRegulatoryCommission,JLD-ISG-2012-01,Revision1,CompliancewithOrderEA-12-049,OrderModifyingLicenseswithRegardtoRequirementsforMitigatingStrategiesforBasisExternalEvents,datedJanuary22,2016(ML1537A163)
 
==DearSirorMadam:==
OnMarch12,2012,theUSNuclearRegulatoryCommission(NRC)issuedarequestforinformationpursuanttoTitle10oftheCodeofFederalRegulations,Section50.54(f)(Reference1).TherequestwasissuedaspartofimplementinglessonslearnedfromtheaccidentattheFukushimaDai-ichinuclearpowerplant.Enclosure2tothe50.54(f)letterrequestedlicenseestoreevaluateflood-causingmechanismsusingpresent-daymethodologiesandguidance.GrandGulfNuclearStation(GGNS)respondedtothe50.54(f)letterbyReferences2and3.SupplementalinformationwasprovidedinReference4.Concurrenttothefloodhazardreevaluation,GGNSdevelopedandimplementedmitigatingstrategiesinaccordancewithNRCOrderEA-12-049,"OrderModifyingLicenseswithRegardtoRequirementsforMitigationStrategiesforBeyondDesign-BasisExternalEvents".InReference5,theNRCaffirmedthatlicenseesneedtoaddressthereevaluatedfloodinghazardswithintheirmitigatingstrategiesassessment(MSA)forbeyond-designbasis(BDB)externalevents,includingthereevaluatedfloodhazards.ThisrequirementwasconfirmedbytheNRCinReference6.GuidanceforperformingMSAforFloodingiscontainedinAppendixGofReference6,endorsedbytheNRCinReference9.ForthepurposeoftheMSAforFloodingandinReference6,theNRCtermedthereevaluatedfloodhazard,summarizedinReference8,asthe"MitigatingStrategiesFloodHazardInformation"(MSFHI).Reference6,AppendixG,describestheMSAforFlooding.InReference8,theNRCconcludedthatthe"reevaluatedfloodhazardsinformation,assummarizedintheAttachmenttothisletter,issuitablefortheassessmentofmitigatingstrategiesdevelopedinresponsetoOrderEA-12-049"forPlantandUnit.TheuseofthesandbagsasdiscussonpagefiveandtenoftheattachmenthasbeenidentifiedasanonconformingconditionfortheuseofmanualoperatoractionsinplaceofapermanentplantmodificationandisbeingaddressedthroughtheGrandGulfCorrectiveActionProgram.TheAttachmenttothisletterprovidestheMitigatingStrategiesAssessmentforFloodingReportforGrandGulfNuclearStation,Unit1.TheassessmentconcludedthattheexistingFLEXstrategycanbesuccessfullyimplementedanddeployedasdesignedforallapplicable-floodcausingmechanisms.ThislettercontainsnonewRegulatoryCommitments.Ifyouhaveanyquestionsorrequireadditionalinformation,pleasecontactJamesNadeauat601-437-2103.Ideclareunderpenaltyofperjurythattheforegoingistrueandcorrect.ExecutedonDecember30,2016.VF/sas
 
==Attachment:==
2016MitigatingStrategiesAssessmentforFloodingDocumentationRequirementsatGrandGulfNuclearStation GNRO-2016/00053Page3of3cc:U.S.NuclearRegulatoryCommissionATTN:Mr.JimKim,NRR/DORL(w/2)MailStopOWFN8B1Rockville,MD20852-2738U.S.NuclearRegulatoryCommissionATTN:Mr.KrissM.Kennedy(w/2)RegionalAdministrator,RegionIV1600EastLamarBoulevardArlington,TX76011-4511Mr.B.J.Smith(w/2)Director,DivisionofRadiologicalHealthMississippiStateDepartmentofHealthDivisionofRadiologicalHealth3150LawsonStreetJackson,MS39213NRCSeniorResidentInspectorGrandGulfNuclearStationPortGibson,MS39150 AttachmenttoGNRO-2016/000532016MitigatingStrategiesAssessmentforFloodingDocumentationRequirementsatGrandGulfNuclearStation r------------------------------.-------.--------,EngineeringReportNo.GGNS-SA-16-0000tRev0PageofUENTERGYNUCLEAREngineeringReportCoverSheetEngineeringReportTitle:2016lVUTIGATINGSTRATEGIESASSESSlVlENTFORFLOODINGDOCUMENl'ATIONREQUIRE1\'1ENTSATGRANDGULFNUCLEARSTATIONNewk8JEngineeringReportType:Revision0Cancelled0Superseded0Supersededby:ApplicableSite(s)IPIDANOlDIP20AN02DIP30ECH0.IAF0GGNSPNPSDRBSDvvDWF30WPODI'Ll'DECNo.64741ReportOrigin:0EntergyVendorVendorDocumentNo.:ENTCORP038-REPT-002Quality-Related:DYesNoDatc:Date:Date:8/1//6.'Date::;1ItfaDesignVerified:
ENERCONPROJECTREPORTCOVERSHEETPAGE1OF116::'1Title:REPORTNO.:ENTCORP038-REPT-0022016MITIGATINGSTRATEGIESASSESSMENTFORFLOODINGDOCUMENTATIONREVISION:0REQUIREMENTSATGRANDGULFNUCLEARClient:EntergySTATIONProjectIdentifier:ENTCORP038ItemCoverSheetItemsYesNo1DoesthisProjectReportcontainanyopenassumptions,includingpreliminaryinformationthatrequireconfirmation?(IfYES,identifytheassumptions.)0[gJ2DoesthisProjectReportsupersedeanexistingProjectReport?(IfYES,identifythesupersededProjectReport.)SupersededProjectReportNo.0IZIScopeofRevision:InitialIssueRevisionImpactonResults:N/ASafety-Related0Non-Safety-RelatedIZIOriginator:JessicaMaddocks..;.,Ay;...."',Reviewer:JeffreyHeadApprover:JaredMonroeIDate:7/xJZOIG,/'\I(,
itENERCONREVISIONSTATUSSHEETPAGE2OF11£:xcc;;'(:ncp*****F.\*frydoy2016MITIGATINGSTRATEGIESASSESSMENTFORREPORTNO.:ENTCORP038-REPT-002FLOODINGDOCUMENTATIONREQUIREMENTSATGRANDGULFNUCLEARSTATIONREVISION:0PROJECTREPORTREVISIONSTATUSREVISIONDATEDESCRIPTION07/8/2016InitialIssueATTACHMENTREVISIONSTATUSATTACHMENTNO.OFREVISIONATTACHMENTNO.OFREVISIONNO.PAGESNO.PAGESN/A ENERCONTABLEOFCONTENTSPAGE3OF11t);(e![;?o(p***..F.v(-.".i.'p:Oji.)Cl.do,2016MITIGATINGSTRATEGIESASSESSMENTFORREPORTNO.ENTCORP038-REPT-002FLOODINGDOCUMENTATIONREQUIREMENTSATGRANDGULFNUCLEARSTATIONREVISION0Section1.Summary2.Documentation2.1NEI12-06,Rev.2,SectionG.2-CharacterizationoftheMSFHI2.2NEI12-06,Rev.2,SectionG.3-ComparisonoftheMSFHIandFLEXDBFlood2.3NEI12-06,Rev.2,SectionG.4-EvaluationofMitigatingStrategiesfortheMSFHI2.4ReferencesPageNo.45571011 ENTCORP038-REPT-002Rev.02016MitigatingStrategiesAssessmentFloodingDocumentationRequirementsGrandGulfNuclearStationAcronyms:*COB-CurrentDesignBasis*ELAP-ExtendedLossofACPower*FHRR-FloodHazardReevaluationReport*FLEXDB-FLEXDesignBasis(floodhazard)*FSG-FLEXSupportGuideline*GGNS-GrandGulfNuclearStation*LIP-LocalIntensePrecipitation*MSFHI-MitigatingStrategiesFloodHazardInformation(fromtheFHRRandMSFHlietter)*MSL-MeanSeaLevel*PA-ProtectedArea*PMF-ProbableMaximumFlood
*PMP-ProbableMaximumPrecipitation*PMWE-ProbableMaximumWaterElevation*SSC-Structures,SystemsandComponentsDefinitions:FLEXDesignBasis:ThefloodhazardforwhichFLEXwasdesigned.FLEXDesignBasisFloodHazard:ThecontrollingfloodparametersusedtodeveloptheFLEXfloodstrategies.1.SummaryTheGGNSFHRR(Ref.7)hasconcludedthatthePMFontheMississippiRiverandStreamAarenotboundedbytheCOBPMFbutareboundedbytheFLEXDBforstoragebuildingdesignandequipmentstaging.PMFonStreamAleadstothelossofthedeploymentpathfromthenorthFLEXstoragebuilding(Site1).Thedeploymentpathfromthesouthstoragebuilding(Site4)remainsavailable,sotheoverallstrategyforthestorageanddeploymentofFLEXequipmentcanstillbeimplementedasdesigned.TheGGNSFHRR(Ref.7)hasconcludedthatthePMFonStreamBisboundedbytheCOBandtheFLEXDB.TheFHRR,asupdatedbyReference9,determinedLIPexceedstheCOBforfloodingattheplantsitebutisboundedbytheFLEXdesignbasis.LIPistheonlyfloodmechanismthatresultsininundationoftheoutdoorareasinthevicinityofSSCsimportanttosafety,andduetotheexistingmitigatingstrategyofsandbagdeployment,doorsealsoninactivedoors,andtherelativelyfastrecessiontimes,theoverallstrategyforthestorageanddeploymentofFLEXequipmentfromthesouthstoragebuilding(Site4)canbeimplementedasdesigned.Otherreevaluatedfloodhazardmechanisms(e.g.,tsunami,channelmigrations/diversions,etc.)areboundedbytheFLEXdesignbasisandCOB,andthereforehavenoimpactonthesite.DetailsoftheFLEXstrategiesalongwiththeboundingfloodwillbediscussedlaterinthisdocument.Page4of11 ENTCORP038-REPT-002Rev.02.Documentation2.1.NEI12-06,Rev.2,SectionG.2-CharacterizationoftheMSFHI.TheFHRR(Ref.7)identifiedthatLIPandPMFoftheMississippiRiverandStreamAarenotboundedbytheCOBfloodelevation.StreamBPMFisboundedbytheCOBfloodelevation.TheFHRRalsoanalyzedthewatershedassociatedwiththeBayouPierreanddeterminedthatthereisnoimpactontheGGNSplantsite.Otherreevaluatedfloodhazardmechanisms(e.g.,tsunami,channelmigrations/diversions,etc.)areboundedbytheCOBandhavenoimpactonthesite.MississippiRiverPMFTheMississippiRiverPMFmaximumfloodheightof106.2ft.MSLis3.2ft.higherthantheCOBfloodheightof103ft.MSL.ThePMWEontheMississippiRiveratGGNSis122.5ft.Thisisthecombinationofstillwaterelevationandwavesetupandwaverunupinducedbythe2-yearwindspeed.Plantgradeisat132.5ft.andanysafety-relatedequipmentorFLEXequipmentisprotectedfromthisevent.Therefore,thiseventdoesnotchallengetheFLEXstrategies.StreamAPMFStreamAPMFmaximumfloodheightof132.1ft.MSLis3.2ft.higherthantheCOBfloodheightof128.9ft.MSL.ThePMWEonLocalStreamAis132.5ft.Thisisthecombinationofstillwaterelevationandwavesetupandwaverunupinducedbythe2-yearwindspeed.Thisfloodlevelleadstolossofcertainpartsofoneofthetwodeploymentpaths(i.e.lossofthepathfromthenorthFLEXstoragebuilding[Site1D.StreamBPMFStreamBPMFmaximumfloodheightdeterminedbytheMSFHIof131.7ft.MSLis1.1ft.lowerthantheCOBfloodheightof132.8ft.MSL.WindwaveheightwasnotcalculatedbecauseStreamBisboundedbyStreamA.Plantgradeisat132.5ft.Therefore,thiseventdoesnotchallengetheFLEXstrategies.BayouPierreTheBayouPierrewasnotevaluatedaspartoftheCOBbutwasevaluatedbytheFHRR.TheFHRRconcludedthatthemaximumfloodleveloftheBayouPierreis130.7ft.,whichiswellbelowtheelevationoftheBayouPierrewatersheddivideelevationofabout175ft.Therefore,thiseventdoesnotchallengetheFLEXstrategies.FloodHeightThemaximumwatersurfaceelevationduetotheLIPatGGNSresultsfromatotalrainfalldepthof19.3incheswithinanhourand31.4incheswithin6hours.IntheimmediatevicinityofGGNSUnit1,predictedmaximumwaterdepthsatsafetyrelatedbuildingentrancesresultingfromtheLIPrangefromapproximately0.3ftto1.0ft(Ref.9)atdoorsprotectingsafetyrelatedequipment.Theseflowdepthscorrespondtowatersurfaceelevationsrangingfrom133.3ft.to133.7ft.(Ref.7and9).ThisisabovetheCOBfloodheightof133.25ft.,andisboundedbytheFLEXDBheightof133.7ftforthesouthFLEXstoragebuilding(Site4).Sandbagsuptoaheightof1.5ft.anddoorsealsatinactivedoors10301andOCT05areusedtoprotecttheseexteriordoorsfromflooding.Therefore,floodingthroughdoorwaysisnotaconcern(Ref.7).Page5of11 ENTCORP038-REPT-002Rev.0Flowvelocitiesarounddoorsrangesfrom0.4fpsto2.1fps(Ref.9).Significantdebrisloading/transportationisnotasafetyhazardduetotherelativelylowvelocityanddepthofLIPfloodwatersinthevicinityofsafety-relatedSSCsatGGNS,inadditiontothelackofnaturaldebrissourcesonsite(Ref.7).FloodEventDurationFlooddurationswereevaluatedatvariouslocationsaroundthepowerblocknearexternaldoorsprotectivesafetyrelatedequipment.Flooddurationsvaryateachlocation,buttheanalyzedlocationstypicallyreachthepeakfloodelevationabout30minutesafterthebeginningoftheLIPevent,droppingrapidlytobelowhalfofthepeakflooddepthapproximately2hoursaftertheonsetoftheLIPevent,whichisbeforePhase2equipmentisdeployed(Ref.7).Flooddepthsalmostcompletelyrecedeby8hourswhichis2hoursbeforeanyPhase2portableequipmentiscredited.ThisgeneraltrendoffloodrecessionisdeemedappropriatefortheSouthStorageBuildingatSite4andtheprimarydeploymentpath(s)fromSite4duetotheproximitytothepowerblockandbecausetheterrainisverysimilar.However,theserecessiontimesmaynotapplytoareasfloodedbyStreamA(specificallytheareaoftheNorthAccessRoadthatisunderapproximately6ftofwater,preventingdeploymentofequipmentfromtheNorthStorageBuildingatSite1)becausewaterisintentionallydivertedtoStreamAfordrainage,thusincreasingtherecessiontime.ItshouldbenotedReference9reanalyzestheLIPflooddepthsbyconsideringroofrunoff,butthisdoesnotchangetheflooddurationsbyasignificantamountsuchthattheFLEXstrategywouldbeaffected.RelevantAssociatedEffectsOnlythesouthstoragebuildingatSite4iswithinthescopeoftheLIPreanalysisduetoitslocationrelativelyclosetothepowerblock.Duetoitsremotelocationandgradeelevation,Site1isnotincludedintheLIPreanalysis.TheLIPreanalysissupportsamaximumexpecteddepthof0.1ft.to0.2ft.atSite1basedupontheadjacentmodeledareas.ThenorthFLEXstoragebuildingatSite1islocatedsuchthatthetop-of-slabelevationisat163ft.,andSite4hasaof-slabelevationof133.2ft.Thefoundation(slab)designsofbothstoragebuildingsincludeaninternalspillcontainmentcurbextending0.5ft.abovethetop-of-slab.Thisresultsinan"effective"top-of-slabelevationof163.5ft.forSite1and133.7ft.forSite4.Thefloodheightsattheselocationsare163.2ft.and133.5ft.respectively.Therefore,giventheconcreteslab,curbheight,grading,anddrainage,thebuildingelevationsaresufficienttoprecludechallenges/impacttothestoredequipment.TheprimarydeploymentpathbetweenthenorthstoragebuildingatSite1andthePArunsalongtheNorthAccessRoadformostofitslength.Inonelocationtheroaddipsapproximately6feetbelowtheLIPfloodelevation(Ref.10).Therefore,itwouldrequiredeploymentoftheFLEX*equipmentfromthesouthstoragebuildingatSite4.Site4islocatedapproximately500ftwestofthePA.TheprimarydeploymentrouteforSite4isnorthalongthePlantAccessRoadgainingaccesstothePAthroughtheSallyPortlocatedjustsouthoftheAdministrationBuilding.ThealternatepathsforSite1andSite4bothrunalongthenorthaccessroad,behindtheUnit2warehouse,andenterthesiteneartheISFSIpadatthenortheasternedgeoftheprotectedarea.Portionsofthispathareunanalyzedforallfloodingscenariossoitisassumedthatthealternatepathsareunavailable.BasedonFigure12ofReference9,themaximumLIPdepthalongtheprimarydeploymentpathfromSite4tothestaginglocationsis1.5feet.BecauseofSite4'sproximitytothepowerblock,itisexpectedthattherecessiontimesforthedeploymentpathfromSite4wouldbesimilartotherecessiontimesforthesafetyrelateddoorsstatedinthe"FloodEventDuration"sectionabove.Therefore,the1.5ft.depthwouldbedecreasedtoapproximately0.75ft.orlessafter2hoursandwouldbealmostcompletelyrecededby8hours.Thelimitingpieceofphase2equipmentwithPage6of11 ENTCORP038-REPT-002Rev.0respecttoheightoffthegroundistheChevy3500truckwhichhasaclearanceofapproximately16"fromthegroundtothecenteroftheexhaustpipepertheRBSFLEXEquipmentWalkdownReport,Attachment10.002toEC64548(Ref.11).GGNSandRBSbothutilizetheChevy3500truckforFLEXequipmentdeployment.Sincenoequipmentisrequiredtobedeployedpriorto2hours,atwhichtimethemaximumflooddepthwouldbeapproximately0.75ft(9inches),thereisnoimpactondeploymentofFLEXequipmentfromthesouthstoragebuildingatSite4duetotheLIP.ItshouldalsobenotedthattheFLEXelectricalequipmentisprotectedfromtherainbydesignandwillnotbesubmersedinfloodwaterssincethetrailerheightsaresufficientlyabovethefloodlevelsatthetimeequipmentisdeployed(atleast7inchesofclearance).Thiswouldalsoprecludeanysignificantrunupduetotraversingthefloodwaterssincethetrailerfloorsareabovethefloodlevelatthetimeofdeployment.ForPhase3,theNSRC'sabilitytotransportequipmenttoStagingAreaB(sitelocationwhereequipmentwillbepre-staged,parked,orplacedpriortomovementintothefinallocation)isdiscussedintheGGNSSAFERResponsePlan(Ref.2)whichincludesmultiplemeansandpathwaysoftransportingNSRCequipmenttothesite.Therefore,transportationofNSRCequipmenttothesiteisdeemedfeasibleandisnotdiscussedfurtherinthisdocument.SincedeploymentofNSRCequipmentoccurslaterintheevent(after24hours),nofurtheranalysisisnecessary.NotethatdeploymentofPhase3equipmentisnotimpactedbyanyfloodmechanismsidentifiedintheFHRR.WarningTimeAfloodwarningtimeof24hoursisusedforpredictionofover12inches(30.5cm)ofrainfromtheNationalWeatherService(Ref.3),andsitepreparationisgovernedbytheOff-NormalEventProcedure05 02-VI-2,"Off-NormalEventProcedure-Hurricanes,Tornadoes,andSevereWeather-SafetyRelated"(Ref.5).2.2.NEI12-06,Rev.2,SectionG.3-ComparisonoftheMSFHIandFLEXDBFloodTable1reflectsdatafromtheFHRRfortheLIPcomparedtothesite'sCOBandFLEXdesignbasisflood.AtableisnotincludedforthePMFfromtheMississippiRiver,StreamA,StreamB,andBayouPierrebecause,asstatedinSection2.1,plantgrade,safety-relatedequipment,thesouthstoragebuildingatSite4,andtheSite4deploymentpathrequiredfortheFLEXstrategyarewellaboveanywind-wavewaterlevelsuchthatthisdoesnotneedtobeevaluated.AnyparameterswheretheFLEXDBflooddoesnotboundtheMSFHIareevaluatedinSection2.3.Page7of11 ENTCORP038-REPT-002Rev.0Table1*FloodCausingMechanism(LIP)orBoundingSetofParametersFloodScenarioParameterPlantFLEXDesignMSFHIBounded(B)CurrentBasisFloodorNotDesignHazardLIPBoundedBasisFlood(NB)byFLEXHazardDB1.MaxStillwaterElevation(ft.MSL)133.25133.7(See133.7BCf)Note1)t52.MaxWaveRun-upElevation(ft.NotIdentifiedNotIdentifiedSeeNote2BMSL)inCOBinFLEXw"0(1)3.MaxHydrodynamic/DebrisNotidentifiedSeeNote3SeeNote3N/A10'(3Loading(psf)intheCOB0Cf)Cf)-cEffectsofSedimentNotidentifiedSeeNote4SeeNote4N/A"0Deposition/ErosionintheCOBccoQ5>5.OtherAssociatedeffects(identifyN/AN/AN/AN/A(1)-leacheffect)"0006.ConcurrentSiteConditionsu:::NotidentifiedSeeNote6SeeNote6BintheCOB7.EffectsonGroundwaterNotidentifiedSeeNote7SeeNote7BintheCOB8.WarningTime(hours)Notidentified2424BintheCOB.e9.PeriodofSitePreparation(hours)Notidentified624NB(1)>cintheCOBw0"0:;::;10.PeriodofInundation(hours)66>15NBocoo'-_:::Ju.O11.PeriodofRecession(hours)78>14NB12.PlantModeofOperationsNormalNormalNormalBOtherOperationsOperationsOperations13.OtherFactorsN/AN/AN/AN/AN/A=NotApplicableAdditionalnotes,'N/A'justifications(whyaparticularparameterisjudgednottoaffectthesite),andexplanationsregardingthebounded/non-boundeddetermination.Thenotenumbersbelowcorrespondtotheparameternumberinthetable.1.TheGGNSFIP(Ref.1)addressedthemaximumfloodheightelevationof133.7ft.MSLfromtheGGNSFHRR.2.Considerationofwind-waveactionfortheLIPeventisnotexplicitlyrequiredbyNUREG/CR-7046andisjudgedtobenegligiblebecauseoflimitedfetchlengthsandflowdepths.3.DebrisloadingisnotconsideredahazardduetotherelativelylowvelocityanddepthofLIPfloodwatersinthevicinityofsafety-relatedSSCs,inadditiontothelackofnaturaldebrissourcesonthesite.4.Erosionandsedimentationarenotapplicabletothissite,andtherefore,donotneedtobeevaluated.(Ref.6)Page8of11 ENTCORP038-REPT-002Rev.05.None6.TheGumbelDistributionwasappliedtothe2-minutewindspeeddatafromNCDCstationatTallulahVicksburgRegionalAirport,todeterminethe2-yearreturnperiodwindspeed,whichwascalculatedtobe45.2mph.7.ThePMPeventimpactonthegroundwaterlevelwasdiscountedasamajorityoftheprecipitationresultingfromaPMPeventdoesnotinfiltratetothelocalgroundwatertablebutinsteadresultsinsurfacewaterrunofftostreamsandrivers.8.None9.None10.LocalIntensePrecipitationandAssociatedDrainagefor6hourprecipitationevent.Thisisbasedonthehydrographatthedoor"OCT5"presentedbyFigure3.1-16intheFHRR.11.LocalIntensePrecipitationandAssociatedDrainagefor6hourprecipitationevent.Thisisbasedonthehydrographatthedoor"OCT5"presentedbyFigure3.1-16intheFHRR.12.None13.NonePage9of11 ENTCORP038-REPT-002Rev.02.3.NEI12-06,Rev.2,SectionG.4-EvaluationofMitigatingStrategiesfortheMSFHI2.3.1.NEI12-06,Rev.2,SectionG.4.1-AssessmentofCurrentFLEXStrategies2.3.1.1.StreamAPMFPMFonStreamAwithcoincidentwindgeneratedwavesresultsininundationoftheprimaryaccessroad,butdoesnotresultininundationofSSCsimportanttosafety.InundationoftheprimaryaccessroadwouldpotentiallyrestrictdeploymentofFLEXequipmentfromthenorthFLEXstoragebuilding(Site1)locatednorthofStreamA.However,asFigure2oftheFinalIntegrationPlanshows(Ref.1),thereisasecondredundantFLEXstoragefacilitylocatedsouthofStreamA,suchthatinundationoftheaccessroadwillnotrestrictdeployment.Therefore,theFLEXstrategiesarenotimpactedbythisevent.(Ref.7)2.3.1.2.LIPThreefloodingscenarioparametersfortheLIParenotboundedbytheFLEXstrategy:PeriodofSitePreparation(hours),PeriodofInundation(hours),andPeriodofRecession(hours).Toaddressthis,protectionofFLEXequipmentagainstexternalfloodingeventswasevaluatedinaccordancewithSection6.2.3.1.1.aofNEI12-06(Ref.8)whichstatesthattheFLEXequipmentisprotectedfromfloodsifitisstoredabovethefloodelevationdeterminedinthemostrecentsitefloodanalysis.FloodingduetoLIPisthecontrollingfloodeventforthenewfloodevaluation.NootherfloodmechanismgenerateswaterelevationswiththepotentialtoimpactsafetyrelatedSSCsorequipmentrelieduponforFLEX.ThemaximumwatersurfaceelevationduetotheLIPatGGNSresultsfromatotalrainfallof19.3incheswithinanhourand31.4incheswithin6hours.IntheimmediatevicinityofGGNSUnit1,predictedmaximumwaterdepthsatsafetyrelatedstructuredoorwaysresultingfromtheLIPrangefromapproximately0.3ftto1.0ft(Ref.9).Table4.3-1intheFHRR(Ref.7)asrevisedbySection6.4.7ofReference9showstheheightofmodeledLIPfloodwaterateachdoorwaytoasafetyrelatedstructurethatcanbepotentiallyimpactedbythisevent.Sandbagsareuseduptoaheightof1.5ft.toprotectentrancestothedieselgeneratorbuilding,standbyservicewaterbuildingsandcontrolbuilding;anddoorsealsatinactivedoors10301andOCT05alsoprotecttheseexteriordoorsfromflooding.Noneoftheprotectionsinplaceforidentifiedsafety-relatedSSCorPMPsealeddoorsareexceededbyLIPfloodwaterheights.Therefore,equipmentintheseareasareprotectedandtheareasremainaccessibleforuseduringaFLEXevent.2.3.2.ConclusionsTheplantresponsestrategiestoanELAPandlossofultimateheatsinkeventusingthecurrentFLEXstrategyandassociatedECshavebeendevelopedinaccordancewiththeGGNSfloodingreanalysis.InundationoftheprimaryaccessroadwouldrequiremobilizationofFLEXequipmentfromthesouthFLEXstoragefacilitylocatedsouthofStreamAsinceinundationpotentiallyrestrictsmobilizationoftheequipmentfromthenorthFLEXstoragefacilitylocatednorthofStreamA.Therefore,thefloodingassessmentwillhavenoimpactontheGGNSFLEXstrategy.EquipmentandpersonnelwillbeavailablesuchthattheGGNSFLEXStrategiescanbeimplementedasdescribedintheFinalIntegratedPlan(Ref.1).Page10of11 ENTCORP038-REPT-002Rev.02.4.References1.GNRO-2016-00006,FinalIntegratedPlanDocumentGrandGulfNuclearStation,April20162.GNRO-SA-15-00001,Rev.001,SAFERResponsePlanforGrandGulfNuclearStation,September8,20153.NEI15-05,Rev.6,WarningTimeforLocalIntensePrecipitationEvents,April20154.EC50275,Rev.2,FLEXBasisEC5.05 02-VI-2,Rev.129,Off-NormalEventProcedure-Hurricanes,Tornados,andSevereWeather,December4,20146.GrandGulfNuclearStation,Unit1-SupplementtoStaffAssessmentofResponseto10CFR50.54(f)InformationRequest-Flood-causingMechanismReevaluation(CACNo.MF1102),December4,20157.51-9195288-000,EntergyFleetFukushimaProgramFloodHazardReevaluationReportforGrandGulfNuclearStation,ML13071A457,March20138.NEI12-06,Rev.2,DiverseandFlexibleCopingStrategies(FLEX)ImplementationGuide,December20159.32-9195573-000,Rev.1,FloodHazardRe-evaluation-LocalIntensePrecipitationGeneratedFloodFlowandElevationsatGrandGulfNuclearStations,September24,201410.EC50287,Rev.0,GGNSFLEXStorageBuilding11.EC64548,Rev.0,AdminECtoIssueFLEXFloodMitigatingStrategiesAssessment(MSA)ReportPage11of11
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