L-17-259, Mitigating Strategies Assessment (MSA) for Flooding
| ML17263A122 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley (DPR-066, NPF-073) |
| Issue date: | 09/20/2017 |
| From: | Bologna R FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CAC MF3286, CAC MF3287, L-17-259 | |
| Download: ML17263A122 (21) | |
Text
September 20, 2017 FENOC' FirstEnergy Nuclear Operating Company Richard D. Bologna Site Vice President L-17-259 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852
SUBJECT:
Beaver Valley Power Station, Unit Nos. 1 and 2 Docket No. 50-334, License No. DPR-66 Docket No. 50-412, License No. NPF-73 Beaver Valley Power Station P.O. Box 4 Shippingport, PA 15077 724-682-5234 Fax: 724-643-8069 10 CFR 50.54(f)
Mitigating Strategies Assessment (MSA) for Flooding (CAC Nos. MF3286 and MF3287)
On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued a letter titled, "Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," to all power reactor licensees and holders of construction permits in active or deferred status. Enclosure 2 of the 10 CFR 50.54(f) letter addresses Near-Term Task Force (NTTF) Recommendation 2.1 for flooding. One of the required responses is for licensees to submit a hazard reevaluation report (HRR) in accordance with the NRC's prioritization plan. By letter dated March 2, 2016, FirstEnergy Nuclear Operating Company (FENOC) submitted the flood HRR for Beaver Valley Power Station (BVPS), Unit Nos. 1 and 2. As indicated in NRC letter dated March 1, 2013, the NRC staff considers the reevaluated flood hazard to be "beyond the current design/licensing basis of operating plants."
Concurrent to the flood hazard reevaluation, FENOC developed and implemented mitigating strategies in accordance with NRC Order EA-12-049, "Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events." By letter dated September 1, 2015, the NRC staff confirmed that licensees need to address the reevaluated flooding hazards within their mitigating strategies for beyond-design-basis (BOB) external events. Guidance for performing mitigating strategies assessments (MSAs) for reevaluated flooding hazards is contained in Appendix G of Nuclear Energy Institute 12-06, Revision 2, which was endorsed by
Beaver Valley Power Station, Unit Nos. 1 and 2 L-17-259 Page 2 the NRC in JLD-ISG-2012-01, Revision 1. In the NRC interim staff assessment for BVPS, dated February 22, 2017, the NRC concluded that the "reevaluated flood hazard information, as summarized in Table 2 of the enclosure [Summary of Results of Flooding Hazard Re-evaluation Report], is suitable for the assessment of mitigating strategies developed in response to Order EA-12-049" for BVPS.
The enclosure to this letter provides the MSA for flooding for BVPS. This assessment indicated that the FLEX strategies, with implementation of a minor change, are adequate and can be implemented without impact from the local intense precipitation (LIP) flood and combined effects flooding (CEF), including wind-generated waves.
There are no new regulatory commitments contained in this letter. If there are any questions or if additional information is required, please contact Mr. Thomas A. Lentz, Manager - Fleet Licensing, at 330-315-6810.
I declare under penalty of perjury that the foregoing is true and correct. Executed on September a, 0, 2017.
Sincerely,
/p;
Enclosure:
Mitigating Strategies Assessment for Flooding cc:
Director, Office of Nuclear Reactor Regulation (NRR)
NRC Region I Administrator NRC Resident Inspector NRR Project Manager Director BRP/DEP Site BRP/DEP Representative
Enclosure L-17-259 Mitigating Strategies Assessment for Flooding (18 pages follow)
Page1of18
BeaverValleyPowerStation MitigatingStrategiesAssessmentforFlooding
DBDesignBasis ELAP-ExtendedLossofACPower FHRRFloodHazardReevaluationReport FIPFinalIntegratedPlan FLEXDiverseandFlexibleCopingStrategies LIPLocalIntensePrecipitationLUHSLossofNormalAccesstotheUltimateHeatSink MSAMitigatingStrategiesAssessment MSFHIMitigatingStrategiesFloodHazardInformation(fromtheFHRRandMSFHIletter)
MSLMeanSeaLevel NORMNuclearOperatingReferenceMaterial NSRCNationalSAFERResponseCenter PMFProbableMaximumFlood UFSARUpdatedFinalSafetyAnalysisReport Definitions:
FLEXDesignBasisFloodHazardThecontrollingfloodparametersusedtodeveloptheFLEX flood strategies.
FLEXDiverse&FlexibleCopingStrategies Phase1Initiallycopebyrelyingoninstalledplantequipment.
Phase2TransitionfrominstalledplantequipmenttotheonsiteFLEXequipment.
Phase3Obtainadditionalcapabilityandredundancyfromoffsiteequipmentuntilpower, water,andcoolantinjectionsystemsarerestoredorcommissioned.
FLEXNEquipmentEquipmentusedisprotectedfromallbeyonddesignbasishazardsandisthe primaryFLEXresponseequipment.
FLEXN+1EquipmentEquipmentusedisNOTprotectedfromallbeyonddesignbasishazards andisusedasanalternatetoFLEXNequipment.
FLEXNSRCEquipmentEquipmentprovidedbytheNSRCtosupportFLEXPhase3strategy.
Unitabbreviations:
ft-feet ft/sec-feetpersecond
Page2of18
- 1.
Summary TheMitigatingStrategiesFloodHazardInformation(MSFHI)providedintheBeaverValley(BVPS)Flood HazardReevaluationReport(FHRR)concludedthatthelocalintenseprecipitation(LIP)andcombined effectsflooding,includingwindgeneratedwaves(CEF),canpotentiallychallengeimplementationofthe FLEXstrategies.BasedonthecompletedMitigatingStrategiesAssessment(MSA),NORMLP7121,after implementationofaminorchangetheFLEXstrategiesareshowntobeadequateandcanbe implementedwithoutimpactfromtheidentifiedMSFHI.Otherreevaluatedfloodhazardmechanisms (i.e.tsunami,channelmigrations/diversions,etc.),areboundedbytheplantdesignbasisandhaveno impactonthesite.
TheMSFHILIPfloodlevelsdevelopadepthaboveseveralcriticaldoorsillsforalimitedperiod.The resultsoftheMSAshowthattheLIPeventwillcausesomedifficultieswithFLEXequipmentdeployment andremovesomeflexibilityduetodeploymentrouteandstagingareaflooding.Impactstothe availabilityofoffsitepersonnelcouldalsochallengeFLEXimplementation.DuetomarginintheFLEX timelineandtheavailabilityofdesignedalternateroutes,FLEXcanbeimplementedasdesignedwith onlyoneexception.BasedupontheFLEXdeploymentstrategyonefloodeddoorisrequiredtobe open.Thisrequiresthatanadditionalfloodprotectionbarrierbeinstalledonanadjacentdoorto preventinternalflooding.
TheMSFHICEFeventisaslowdevelopingevent,withseveraldaysofwarningandpreparationtime.
TheexistingabnormaloperatingprocedureswouldrequiretheshutdownofbothUnitswellin advanceoftheCEFevent.AsdescribedintheMSFHIletter,thedesignbasisstillwaterelevation (730.0ft)isutilizedinthisassessmentinsteadofthevaluesubmittedintheFHRR(727.53ft).The floodingresultingfromtheCEFexceedthedesignbasisbutdoesnotadverselyaffectsafetyrelated structures.FLEXimplementationisachievableinnonfloodedareas.ItisrecognizedthattheCEF eventmayrequireutilizingalternatedeploymentpathsandstaginglocationsbuttheyarealready describedintheexistingFLEXstrategy.FLEXequipmentstoragebuildings,theNSRCstagingareaand theequipmentdeploymentroutestothesiteareathigherelevationsandunaffectedbytheCEFevent.
TheFLEXresponsetimelinehasbeenreviewedandverifiedtoensureFLEXstrategiescanbe implementedtoaddresstheLIPandCEFimpacts.
- 2.
Documentation 2.1NEI1206,Rev.2,SectionG.2-CharacterizationoftheMSFHI TheMSFHItobeevaluatedintheMSAwasdeterminedintheBeaverValleyFHRR,Rev0,and subsequentlyasTable2inNRCcorrespondenceLetterML17040A011,withEnclosure ML17039A550.ThisletteridentifiesthestaffreviewandresultsoftheauditoftheFHRR,aswellas anyRequestforAdditionalInformationorsupplementaldata.
TheLIPandCEF,includingwindgeneratedwaves,exceedthecurrentdesignbasis.
LocalIntensePrecipitation(LIP)
FloodHeight Themaximumwatersurfaceevaluation(WSE)slightlyexceedsthecurrentdesignbasis.ForUnit1, thelargestinundationdepthabovedoorelevationsis0.4ft,whichresultsin8doorsbeingflooded.
ForUnit2,thelargestinundationdepthabovedoorelevationsis0.5ft,whichresultsin4doors
Page3of18 beingflooded.Anevaluationconcludedthat,basedonthefloodingdepthandduration,thereisno impacttosafetyrelatedequipmentat10ofthe12doors.Duetotheprolongeddurationofthe floodwater,thefinaltwodoorsweremodifiedforfloodmitigation(discussedunderfloodevent duration).
Also,onefloodeddoorisrequiredtobeopenforFLEXactivities.Thisrequiresthatanadditional floodprotectionbarrierbeinstalledonanadjacentdoortopreventinternalflooding.
FloodEventDuration Theflooddurationabovethedoorelevationis15minutesformostofthedoors.However,several doorsareinundatedabovethedoorelevationforupto1.5hours,andmorethan6hoursattwo doorlocations.BasedontheresultsoftheFHRR,thetwodoorsfloodedfor6hoursweremodified withfloodprotectionbarriers.
RelevantAssociatedEffects TherearenoassociatedeffectsrelatedtoaLIPevent.
Thecalculatedhydrostaticandhydrodynamicloadsforallsafetyrelatedstructuresaresignificantly lessthanthedesignbasiswindloadsandloadsproducedfromthedesignbasistornado.
Verylittledebrisorsedimentwillbedepositedbasedontheimpermeablematerialsurrounding thepowerblockarea,preventingdebrisandsedimentbeingentrainedinfloodwaters.
TherearenospecificconcurrentsiteconditionsidentifiedduringaLIPevent.
TheLIPeventisashortdurationevent,andanycombinationofhighwindsandfloodingwouldbe shortlived.Iceformationisnotcredible.
Therewillbenoadversegroundwatersurchargeeffectsduetotheshortdurationofinundation andimpermeablematerialssurroundingthepowerblockarea.
WarningTime ALIPeventprovideslimitedwarningtime;therefore,theevaluationoftheFLEXstrategieswas performedassumingtheLIPeventcouldoccuratanypointontheFLEXtimeline.Itwasconcluded thatsufficienttimemarginexiststodelayFLEXactivitiesuntilLIPfloodwatershavereceded.
(Basedoninstallationofafloodbarrierondoor1F353,discussedlaterinsection2.3.2).
CombinedEffectsFlooding,includingwindwaveeffects(CEF)
FloodHeight AsdescribedintheMSFHIletter,thedesignbasisstillwaterelevation(730.0ft)isutilizedinthis assessmentinsteadofthevaluesubmittedintheFHRR(727.53ft).TheoverallCEF(withwind generatedwaves)valuesdidnotincrease,asindicatedintheMSFHIletter,dueprimarilytothe extremeconservativeassumptionsandinputsusedinthewindwaverunupanalysisfortheFHRR.
ThereevaluatedCEFmaximumdesignbasisvaluesareexceededinthreelocations:732.8ftatthe Unit1TurbineBuildingNorthwall,734.0ftatthegroundslopeapproachingtheUnit2Reactor Building,and734.5ftatthegroundslopeapproachingtheEmergencyOutfallStructure(EOS).The waverunupattheUnit2PowerBlock(ReactorBuilding)andtheEOSlocationismaintainedonthe groundslopeapproachingthestructuresandthereforedoesnotimpactthesafetyrelated structures.
Basedontheoverallbuildingarrangement,thewaverunupatUnit1TurbineBuildingwillresultin nowaveactionorwaveenergyaffectingtheinternalServiceBuildingfloodbarrierwalls.Multiple
Page4of18 obstructionswouldpreventthewaveenergytransferincludingtheTurbineBuildingnorthwall whichismetalsiding,numerouslargediameterpipingruns,heavyequipmentlocatedwithinthe TurbineBuilding,andthereinforcedconcreteTurbineBuildingsouthwall.TheTurbineBuilding southwallisadjacenttotheServiceBuildingnorthwall(floodbarrier)witha4inchseismicshake spaceinbetween.
FloodEventDuration TheCEFeventisslowdevelopingandallowsforappropriatepreparations.Forthisdiscussion,the periodofinundationbeginsoncetheOhioRiverreaches690ft,andthenrecedesbacktothis value.Thisisanarbitrarilychosenvalue,whichis15feetbelowtheoperatingdeckoftheIntake Structureandlowestelevationsofthepowerblockarea,andwaschosenbasedonavailabledesign basisinformation.Thisresultsinapproximately100hoursoffloodingonsite.TheFHRRUSACE hydrographsforthebasinwidePMFprovidesthattheinundationlastsforabout74hoursforthe 690ftelevation.Itshouldbenotedthatthesitefloodprotectionfeaturesarenotspecifically sensitivetoanysmalldifferenceofinundationtimeframes.
RelevantAssociatedEffects Nosignificantdebrisisexpectedtobetransportedtothepowerblockareabasedonthelow velocitiesoftheCEFevent,andthemultitudeofobstacles,i.e.fencelines,nonsafetyrelated structures,andtopographicalfeatures,aroundthepowerblockareapreventingdebristransport.
Thepowerblockandsurroundingareaaremostlymacadamandconcrete.Basedonthesehard materialsandlowvelocities(<10ft/sec)ofthefloodwaters,scourisnotconsideredanissue.Itis assumedthattheCEFwillresultinsomesoildepositionatthesite,however,itwillnotinhibitthe safeoperationofthestation.
ThespecificadditionaleffectsidentifiedduringaCEFevent,isthewindspeedrequiredtogenerate thewaveeffectsduringthesitespecificPMF.Although,thedesignbasiswindspeedvalue(40 mph)forcreationofwindgeneratedwavesisexceededbythenewhazardwindspeed(50mph)it isboundedbytheexistingdesignbasiswindspeedsforthepowerblockstructuresandtheIntake structure(80mph).Thewaverunupeffectswerediscussedpreviously.
WarningTime Thereisnospecificwarningtime;however,theCEFeventisslowdevelopingandbothunitswillbe shutdownwellinadvanceofthepeakoftheCEF.Basedonexistingabnormaloperatingprocedures (AOP),initialactionsoccurwhentheriverwaterlevelreaches670ft.TheAOPdirectsamultitude ofpreparationactivities,includingmobilizingadditionalpersonneltobeonsite,andincreasesthe monitoringtimeastheriversrises.Theduelunitplantshutdownwillcommenceat695ftifflood predictionsabove700ftareindicated.Additionally,theexistingsevereweatherAOPwillbe enteredoncesustainedwindsreach>40mph.
2.2NEI1206,Rev.2,SectionG.3-ComparisonoftheMSFHIandFLEXDBFlood Thefollowingtablesprovidethecomparisonoftheplantdesignbasis,FLEXdesignbasisandthe MSFHIforthevariousfloodparameters,asapplicable.Thenotesfollowingthetablesprovidemore explanationofeachofthespecificparameterslistedinthetables.
Table1:LocalIntensePrecipitation Table2:CombinedEffectsFlooding-whichincludestheeffectsofthePMFproducingthe maximumWSEoftheOhioriver+windgeneratedwaveaction.
Page5of18 Table1-FloodCausingMechanism:LocalIntensePrecipitation
FloodScenarioParameter (Theattachednotesprovide furtherdiscussionforeach correspondingnumbered parameterlisted)
PlantDesign BasisFlood FLEXDesign BasisFlood Hazard MSFHI MSFHI Bounded(B) or NotBounded (NB)
FloodLevelandAssociatedEffects 1.MaxStillwaterElevation BVUnit1 Notidentified
BVUnit2 732.5ftto 735.4ft BVUnit1 Notidentified
BVUnit2 732.5ftto 735.4ft MaximumBV Unit1 735.9ft
MaximumBV Unit2 735.7ft NB 2.MaxWaveRunup Elevation Notdiscussedin UFSAR Notdiscussedin UFSAR Minimal B
3.Max Hydrodynamic/Debris Loading Notdiscussedin UFSAR Notdiscussedin UFSAR Minimal B
4.EffectsofSediment Deposition/Erosion Notdiscussedin UFSAR Notdiscussedin UFSAR None B
5.Otherassociatedeffects (identifyeacheffect)
None None None B
6.ConcurrentSite Conditions Notdiscussedin UFSAR Notdiscussedin UFSAR None B
7.EffectsonGroundwater Levelchanges withOhioRiver levelchanges Levelchanges withOhioRiver levelchanges Minimal B
FloodEventDuration 8.WarningTime(hours)
Notdiscussedis UFSAR Notdiscussedis UFSAR Notrequired NB 9.PeriodofSite Preparation(hours)
Notdiscussedin UFSAR Notdiscussedin UFSAR Notrequired NB 10.PeriodofInundation (hours)
OneDoorfor>1 OneDoorfor>1 Maximum>6 NB 11.PeriodofRecession (hours)
Notdiscussedin UFSAR Notdiscussedin UFSAR Notrequired NB Other 12.PlantModeof Operations Notdiscussedin UFSAR Notdiscussedin UFSAR Mode16 NB 13.OtherFactors None None None B
- AllelevationsareinNGVD29/MSLunlessotherwisenoted.
Page6of18 Thenotesbelowalignwiththedatainthetablenumberingandprovideanyotherrelevantinformationfor thetableinformation.
1.
SincetheLIPisnotspecificallydiscussedintheBVPS1UFSAR,andtherearespecificMSFHIvaluesthatare abovetheDBvaluesatUnit2,itisconsiderednotboundedatbothUnits.
Ref.CalculationDSC6794,FHRRSection2.1.1&3.8,BVPS1UFSARSection2.3,BVPS2UFSARSection 2.4.2.3.2 2.
TherewasnowaverunupvaluesassociatedwiththeMHFLILIP.Theeventisshortdurationandthe relativelyshallowstandingwaterrecedesquickly.TheUFSARsdonotaddresswaverunupassociatedwith floodingfromtheLIP.NeitherthedesignbasisnortheMSFHIidentifiedthisasanissue.Thisitemis bounded.
Ref.BVPS1UFSARSection2.3,BVPS2UFSARSection2.4.2.3.2,FHRRSection3.8,NRCMSFHILetter 3.
NospecificdebrisloadingwasdiscussedintheFHRRorprovidedintheLIPcalculationsrelatedtoload effectsonpowerblockstructures.Hydrostaticandhydrodynamicloadsonpowerblockstructureswere calculatedintheMSAreport.Thecalculatedloadsforallsafetyrelatedstructuresaresignificantlylessthan thedesignbasiswindloadsandthedesignbasistornado(360mph,330psf).Nodebrisloadsareanticipated.
Duetothelayoutofthesite,anyentraineddebrisfromtheupperslopeswillbecapturedbythevarious barriers,vehiclebarriersystemandfences,priortoimpactinganystructures.Thebuildupofdebriswould reducetheamountoffloodwaterwhichcouldpassthroughtheseupstreambarriersandenterthepower blockarea.Waterbornedebrisimpactloadswouldbesignificantlylessthanthedesignbasistornadowind drivenmissileloads,sothereisnoconcernwiththeseloadsonsafetyrelatedstructures.
Numerousnonsafetyrelatedstructureshavecalculatedloadingwhichexceedsdesignbasiswindspeed loadingincludingtheUnit1AuxBay,WarehouseExtension,Unit2TurbineBuilding,CondensatePolishing BuildingandtheSouthOfficeShopBuilding.However,collapseorfailureofthestructuresisnotcredibledue totheloadingproducedbytheLIPbeingbasedontherelativelyshallowdepthsaroundthebuildings.
Additionally,thenonsafetyrelatedstructuresarenotfloodproof,andtherewouldbeequalbuildupof pressureoneachsidetheexteriorwallseffectivelyremovingthehydrostaticloads.Floodinginthese buildingswouldnotaffectanysafetyrelatedequipmentastheelevationsbelowthefloodwaterheightsdo notcommunicatetosafetyrelatedareasoftheplant.
TheLIPcalculationisconservativeitassumesthesitedrainagesystemisnotfunctional,allroofdrains contributetotheLIPandthatthePeggsRunPMFcontributestotheLIPevent.Inactualpractice,itis expectedthesesystemswillfunctionminimizingthedepthofthefloodwatersassociatedwithaLIPevent.
Therefore,thehydraulicloadspresentedarehighlyconservative.Eachofthebuildingswithloadsgreater thantheirdesignwindloadingwerereviewedintheassociatednotesoftheMSAreport.Ineachcasethe impactofthehydrodynamic/hydrostaticloadsweredeterminedtobeinconsequential.Neitherthedesign basisnortheMSFHIidentifiedthisasanissue,andtheloadingsarefoundtobeinconsequential.Thisitemis bounded.
Ref.CalculationDSC6794,BVPS1UFSARSection2.7.1.2&2.7.2.3,BVPS2UFSARTable3.55,Enercon ReportFNOCBV060REPT001
Page7of18 4.
BeaverValleyislocatedonterracedterrain.TheaveragevelocityofthefloodwatersduringtheLIPvaries withtheterrain.Somesignificantvelocitiesexistinareaswheretheterraindropssignificantly.Theseare localizedareas,andnonearedirectlyadjacenttopowerblockstructures.Velocitiesinthepowerblockareas arelessthan5ft/sec.Verylittledebrisorsedimentwillbedepositedbasedontheimpermeablematerial surroundingthepowerblockarea,preventingdebrisandsedimentbeingentrainedinfloodwaters.Thisarea isconcreteand/ormacadam.Thishardmaterialwillalsopreventscour,soitisnotconsideredtobecredible.
NeitherthedesignbasisnortheMSFHIidentifiedthisasanissue,anditisnotconsideredtobecredible.This itemisbounded.
Ref.BVPS1andBVPS2UFSARChapter2,FHRR,CalculationDSC6794,EnerconReportFNOCBV060REPT 001 5.
Noadditionalassociatedeffectswereidentified.Neitherthedesignbasis,northeMSFHIidentifiedanyother detrimentaleffects.Thisitemisbounded.
Ref.BVPS1andBVPS2UFSARChapter2,FHRR 6.
NospecificconcurrentsiteconditionshavebeenidentifiedduringaLIPevent.Itisreasonabletoassume therewillbewindsassociatedwiththestorm.However,thetimeframeoftheLIPeventisashortduration event,andanycombinationofhighwindsandfloodingwouldbeshortlived.Iceformationisnotcredible.
Neitherthedesignbasis,northeMSFHIidentifiedanyotherconcurrentsiteconditions.Thesevaluesare markedbounded.
Ref.BVPS1andBVPS2UFSARChapter2,FHRR,CalculationDSC6794 7.
Therewillbenoadversegroundwatersurchargeeffects.Theshortdurationofinundationandimpermeable materialssurroundingthepowerblockareawouldpreventanychangeinthegroundwaterelevation.Perthe UFSAR,groundwaterelevationsequalizewithOhioRiverelevations.WiththeLIPbeingasmallgeographical eventitisnotexpectedtocauseasignificantincreaseintheOhioRiverwaterlevel.Thisitemisconsidered bounded.
Ref.BVPS1UFSARSection2.3.2.3,BVPS2UFSARSection2.5.4.10.2,FHRR 8.
NospecificwarningtimeisidentifiedineitherthedesignbasisortheMSFHI.AOP75.1ActsofNature SevereWeathercontainsguidanceandreferencetoavailableweatherinformation.IntheeventofaSevere ThunderstormWarningforBeaverCountytheAOPisenteredandactionsaretakenperAttachment3ofthe AOP.TheAOPrecognizesthattimemaybelimitedtoperformtheactions.Thereisnoproceduredirecting actionspecificallyrelatedtofloodingfromaLIPevent,andnoactionsarespecificallyneededtorespondtoa designbasisLIPevent.However,floodingimpactsfromtheFHRRLIPeventhavebeenevaluatedin CalculationDSC0368,andpermanentcorrectiveactionstakentopreventsignificantimpactsfromtheMSFHI LIPevent.ThereisnospecificneedforwarningtimedeterminedfromreviewoftheMSFHILIP,asrequired actionswouldhavealreadybeenperformedprocedurallypriortoanyforecastingofanLIPevent.
SincethedesignbasisdoesnotdiscussthisissueandtheMSFHIdoes,itisconsiderednotbounded; however,therearenoconcernsassociatedwiththewarningtimeattributeoftheLIP.
Page8of18
Ref.FHRR,CalculationDSC6794,CalculationDSC0368,1/2OM53C.4A.75.1ActsofNatureSevereWeather (AOP75.1) 9.
AsdiscussedinNote8,sitepreparationsforaseverethunderstorm,apotentialprecursortoaLIPeventis containedinAttachment3ofAOP75.1.TheresultantfloodfromaLIPeventdevelopsrapidly.Areviewof thefloodinghydrographsinCalculationDSC6794indicatesminimalpreparationtimewillbeavailable.The SitehasalreadyevaluatedtheLIPeventeffectsasdiscussedinNote8.Inadditiontothespecificactions alreadytakenasidentifiedinAttachment3,itisassumed,ingeneral,thatsitepersonnelwillclosedoors, hatchesandotherwateringresspathsintheeventofsevererainfall.Standardpracticehaspersonnelclose exteriordoorstosafetyrelatedareasoftheplant.NopreparationsarerequiredforthedesignbasisorNRC InterimStaffResponse(ISR)MSFHILIP.
SincethedesignbasisdoesnotdiscussthisissueandtheMSFHIdoes,itisconsiderednotbounded; however,therearenoconcernsassociatedwiththesitepreparationattributeoftheLIP.
Ref.BVPS1andBVPS2UFSARChapter2,FHRR,CalculationDSC6794,CalculationDSC0368,1/2OM 53C.4A.75.1ActsofNatureSevereWeather(AOP75.1) 10.
Thetotalsiteinundationperiodinthepowerblockareaislongerthan6hours(lengthofstorm)atvarious locations,howeverthereisonlyashortdurationoftimeabovemostcriticalplantdoorthresholds.
CalculationDSC0368hasdeterminedalldoorssusceptibletowateringressduringaLIPeventresultinno effectonsafetyrelatedSSCs,exceptfortwodoors.ECP150357installedpermanentbarriersatthetwo doorswhichremovedthepotentialimpacts.Formostofthe6hourtimeframedepthsandvelocitiesaround thesiteareinconsequential.
InundationoftheFLEXhaulpathsandstagingareaswillpersistforgreaterthan6hoursduetolowspotsand ponding.Althoughthereisstillwaterabovegrade,thedepthsandvelocitywillallowOperatorstoaccessthe equipmentandconnectionpointstosupportFLEXactions.
TheUFSARdescribesonedoorexceededduringthe1hourLIPevent.Sincethedesignbasisvalueislessthan theMSFHIvalue,andotherdoorsareexceeded,itisconsiderednotbounded;however,thereareno concernsassociatedwiththeperiodofinundationattributeoftheLIP.
Ref.BVPS1andBVPS2UFSARChapter2,FHRR,CalculationDSC6794,EnerconReportFNOCBV060REPT 001,ECP150357 11.
TheperiodofrecessionisnotsignificantfortheLIPeventatthesite.Duetothetopographyandvarious depthsaroundthesitearecessiontimeisnotclearlydefinablefortheMSFHILIP.However,after6hoursthe raineventends,andthewaterwouldquicklydraintothenorthduetotheslopingtopographyofthesite towardstheOhioRiver.
CalculationDSC6794providesthatduetotheassumptionthatalargedrainageculvertisblocked,thereisa floodpotentialatthealternatesiteaccess.AsshownintheMSAreport,thenormalsiteaccesspointwillbe impactedduringaLIPduethehazardousconditionsatpoint2and9.AreviewofEnerconReportFNOCBV 060REPT001,showsvelocitiesintheaccessareacanbeashighas10ft/secwithdepthsof2ftforbrief periodsoftime.Duetotheextremeslopedareatothenorth,oncetherainhasstoppedortaperedthe resultantflooddepthsandvelocitieswilldecreaseallowingaccessforsitepersonnel.Itmayalsobepossible
Page9of18 tousethenormalsiteaccessduringtheLIPusinglargevehicleswithsufficientgroundclearanceandweight totraversethefloodedareas.Ifthisisassumed,thereisnoLIPimpact.Sincethedesignbasisdoesnot discussthisandtheMSFHIdoes,itisconsiderednotbounded;however,therearenoconcernsassociated withtheperiodofrecessionattributeoftheLIP.
Ref.BVPS1andBVPS2UFSARChapter2,FHRR,CalculationDC6794,EnerconReportFNOCBV060REPT 001 12.
PlantmodesarenotdiscussedintheUFSARsrelatedtoLIPfloodingevent.However,thedesignbasisLIP doesnotimpacttheplantsabilitytoshutdownorsafelymaintainedshutdown.TheFLEXstrategydoes identifydifferentresponsesbasedonPlantmodeandtheavailabilityofsteamgeneratorsforheattransfer.
SincethedesignbasisdoesnotspecificallydiscussthisandtheMSFHIdoes,itisconsiderednotbounded; however,therearenoconcernsassociatedwiththeplantmodesofoperationsattributeoftheLIP.
Ref.BVPS1andBVPS2UFSARChapter2,FHRR 13.
NoadditionalfactorswereidentifiedassociatedwiththedesignbasisorMSFHILIP.Duetotheabsenceof loosedebristobemovedbytheLIPfloodwatersinsidetheprotectedarea,andthegenerallowwater depthsaroundstructures,waterborneprojectilesarenotconsideredcredible.Sinceneitherthedesignbasis northeMSFHIidentifiedthisasanissue,theotherfactorsattributeismarkedbounded.
Ref.BVPS1andBVPS2UFSARChapter2,FHRR,EnerconReportFNOCBV060REPT001
Page10of18 Table2-FloodCausingMechanism:CEF,IncludingWindGeneratedWaves
FloodScenarioParameter (Theattachednotesprovide furtherdiscussionforeach correspondingnumbered parameterlisted)
PlantDesign BasisFlood FLEXDesign BasisFlood Hazard MSFHI MSFHI Bounded(B) or NotBounded (NB)
FloodLevelandAssociatedEffects 1.MaxStillwater Elevation 730ft 730ft 730ft B
2.MaxWaveRunup Elevation
IntakeStructure 736.7ft
Unit1Turbine BuildingNorth WallNot Protected
Unit1Interior Wall(SBNorth Wall) 730ft
Unit2Structures 730ft
EOS 730ft
IntakeStructure 736.7ft
Unit1Turbine BuildingNorth WallNot Protected
Unit1Interior Wall(SBNorth Wall) 730ft
Unit2Structures 730ft
EOS 730ft
IntakeStructure 734.0ft
Unit1Turbine BuildingNorth Wall 732.8ft
Unit1Interior Wall(SBNorth Wall) 730.0ft
Unit2Structures 734.0ft
EOS 734.5ft
B
NB
B
NB
NB
3.Max Hydrodynamic/Debris Loading IntakeStructure 736.7ft
Category1 Structures IntakeStructure 736.7ft
Category1 Structures IntakeStructure 734.0ft
Category1 Structures 730.0ft B
B
4.EffectsofSediment Deposition/Erosion Notdiscussedin UFSAR Notdiscussedin UFSAR Minimal B
5.Otherassociated effects (identifyeacheffect)
N/A N/A None B
6.ConcurrentSite Conditions WindSpeed40 mph WindSpeed40 mph WindSpeed50 mph NB 7.Effectson Groundwater 730ft 730ft 730ft B
Page11of18 FloodScenarioParameter (Theattachednotesprovide furtherdiscussionforeach correspondingnumbered parameterlisted)
PlantDesign BasisFlood FLEXDesign BasisFlood Hazard MSFHI MSFHI Bounded(B) or NotBounded (NB)
FloodEventDuration 8.WarningTime(hours)
>24
>24
>24 B
9.PeriodofSite Preparation(hours)
Approx.
78 Approx.
78 Approx.
78 B
10.PeriodofInundation (hours)
Approx.100 Approx.100 Approx.
74 B
11.PeriodofRecession (hours) 70 70 30 B
Other 12.PlantModeof Operations Mode16 Mode16 Mode16 B
13.OtherFactors N/A N/A None B
- AllelevationsareinNGVD29/MSLunlessotherwisenoted.
Page12of18
Thenotesbelowalignwiththedatainthetablenumberingandprovideanyotherrelevant informationforthetableinformation.
1.
TheNRCMSHFIletterprovidesthestillwaterelevationtouseintheMSAas730ft.
AstheMSFHIstillwaterelevationisthesameastheDB,itisconsideredbounded.
References:
NRCMSFHILetter,BVPS1andBVPS2UFSARChapter2 2.
BVPS1UFSARSection2.3.8.4states,TheIntakeStructureistheonlysafetyrelatedstructurewhich willbesubjectedtotheeffectsofcoincidentwavesandassociatedrunup.FromtheNRCMSFHI lettertheCEFonsitegradeis:732.8ftattheUnit1TurbineBuildingnorthwall,734.0ftattheground slopeapproachingUnit2ReactorBuilding,and734.5ftatthegroundslopeapproachingthe EmergencyOutfallStructure(EOS).
TheCEFapproachingtheUnit2PowerBlock(ReactorBuilding)andtheEOSlocationismaintainedon thegroundslopeapproachingthestructuresandthereforedoesnotimpactthesafetyrelated structures.However,itisabovethedesignbasisvalueandthereforeisnotbounded.TheIntake StructureMSFHICEFvalueislessthantheDBvalueandisconsideredbounded.AstheMSFHICEF valueisabovetheDBvaluefortheUnit1TurbineBuildingnorthwallitisconsiderednotbounded.
IntheMSFHIletter,BeaverValleyagreedtousetheDBstillwaterelevation(SWE)fortheMSAreport insteadofthevaluessubmittedintheFHRR.TheoverallCEFvaluesdidnotincreaseasindicatedinthe MSFHIletter.Thisisduetotheextremeconservativeassumptionsandinputsusedinthewindwave runupanalysisfortheFHRR.
However,usingthedesignbasisstillwaterelevationraisestheSWEfromthatsubmittedintheBVPS FHRR.DuetothehigherSWE,theconservatismsinthewindwaveanalysishavebeenreviewedwith respecttotheUnit1internalServiceBuildingnorthwall(southoftheTurbineBuilding).Theinternal waveswellestimatedwithintheUnit1TurbineBuildingwasdeterminedtobeanoverconservative assumptionintheFHRRandunrealisticbasedonsiteconfiguration.Thefollowingrefinementismade tothewindwaveanalysis.
ThenorthwalloftheUnit1TurbineBuildingexperiencesanoverallPMFSWEof730.0ftandwave runupof2.8ftpertheMSFHIletter.SincetheTurbineBuildingnorthwallisnotafloodbarrierthe SWEoneachsideofthewallwouldbethesame(730.0ft);however,thewaveenergywouldnotbe abletotraveltotheDBfloodbarrierwallattheTurbineBuilding/ServiceBuildingInterface.Multiple obstructionswouldpreventthewaveenergytransferincludingtheTurbineBuildingnorthwall,which ismetalsiding,numerouslargediameterpipingruns,heavyequipmentlocatedwithintheTurbine Building,andthereinforcedconcreteTurbineBuildingsouthwall.TheTurbineBuildingsouthwallis adjacenttotheServiceBuildingnorthwall(floodbarrier)witha4inchseismicshakespacein between.Basedontheoverallarrangement,nowaveactionorwaveenergycanreasonablybe consideredtoreachtheinternalServiceBuildingfloodbarrierwalls.TheCEFSWEattheinternal ServiceBuildingfloorbarrierwallsistakentobetheSWEof730.0ft.The730.0ftisequaltoand boundedbytheexistingUFSARdesignbasis.
BasedonthisdiscussionallCEFwatersurfaceelevationshavenoadverseimpacttoanysafetyrelated SSCrequiredforsafeshutdown.
Page13of18
Reference:
CalculationDSC6799,FHRRSection2.1.4,2.1.8,BVPS2UFSARSection2.4.3.6,BVPS1 UFSARSection2.3.8.4 3.
NospecificdebrisloadingwasprovidedintheCEFcalculationsrelatedtotheeffectsonpowerblock structures.TheCEFlevelimpactstheIntakestructureandtheUnit1TurbineBuilding.TheCEFatUnit 2donotreachthepowerblockstructures.TheintakestructureCEFlevelsareboundedbytheexisting DB.TheUnit1TurbineBuildingisnotbounded;however,itisnotdesignedtobefloodproofduringa PMF.Asdescribedinthedesignbasis,theUnit1TurbineBuildingfloodingabove725.5ftwillallow floodingofthePipeTunnel,whichinturnallowsfloodingoftheAuxiliaryBuildingandaportionofthe northSafeguardsarea.ThisfloodingoffsetsthebuoyancyeffectsonthebuildingsduringaPMF.This floodingisdescribedandboundedbytheexistingDB.
Thesiteisrollinghillterrainwiththepowerblockstructureslocatedonaterrace.Nosignificantdebris isexpectedtobetransportedtothepowerblockareabasedonthelowvelocitiesoftheCEFevent, andthemultitudeofobstacles,i.e.fencelines,nonsafetyrelatedstructures,andtopographical features,aroundthepowerblockareapreventingdebristransport.TheIntakeStructureislocated nexttotheOhioRiverandismoreexposedtothefloodwatersthanthepowerblockstructures.The safetyrelatedareasoftheintakestructurearedesignedtowithstandthedesignbasistornado loading,330psf,onexteriorwallsandthefullspectrumoftornadomissiles.Additionally,theintake structureisdesignfortheloadingproducedbytheequaldesignbasisfloodof730.0ft.
ThevaluesareatorbelowtheDBbycomparisonandqualitativeevaluationandisthereforebounded.
Reference:
CalculationDSC6799,FHRR3.7.4,BVPS1UFSARSection2.3.3,2.7.3.2.5,2.7.11,2.3.8.4, 2.3.3,2.3.8.4,9.7.1,9.7.3,9.7.4,9.7,14.1.14.2 4.
Thesiteisrollinghillterrainwiththepowerblockstructureslocatedonaterrace.Thepowerblock andsurroundingareaaremostlymacadamandconcrete.Basedonthesehardmaterialsandlow velocities(<10ft/sec)ofthefloodwatersscourisnotconsideredanissue.Theactualestimated velocityofthefloodwaterontheriverbanksduringaPMFis3mphor4.4ft/sec.
ItisassumedthattheCEFwillresultinsomesoildepositionatthesite,andpotentiallyinternaltothe TurbineBuilding.Astheadditionalareasfloodedduringthisevent,discussedinNote3,arewithinthe existingDB,soildeposition,shoulditoccurwillnotinhibitthesafeoperationofthestation,asthese areasarenotdesignedtobeprotectedfromfloodinginaPMF.TheCEFwatersdonotreachtheUnit2 PowerBlockstructures,andthereforescourisnotaconcern.
TheIntakeStructureissurroundedbyfloodwatersduringtheDBandMSFHICEF.TheIntakeStructure issupportedonbedrock.Therefore,scouringisnotaconcern.Thesandsandgravelsofthelower terraceoverwhichtheriverintakelinespasshavebeenrecompactedtomedianrelativedensities exceeding75percentalongtherouteofthesepipelines.Therefore,thisisnotahazard.
IntheCEFscenario,theplantisrequiredtoshutdownandcooldowninadvanceoftherisingflood waters.BasedonfloodlevelsandwindspeedsintheCEFscenarioitisexpectedmostmakeuptanks willremainviableandprecludetheneedforlongtermriverwaterusage.
SincetheUFSARandDBdonotdiscussthisissueandtheMSFHIisminimal,itisconsideredbounded.
Page14of18
References:
CalculationDSC6799,FHRR3.7.4,BVPS1UFSARChapter2,Appendix2H,Attachment 2.3A,Figure16,AOP75.2ActsofNatureFlood 5.
Noadditionalassociatedeffectswereidentified.
SincetheUFSARandDBdonotdiscussthisissueandtheMSFHIdidnotidentifyanyadditionaleffects, itisconsideredbounded.
Reference:
CalculationDSC6799,FHRR3.7.4,BVPS1UFSARChapter2,BVPS2UFSARChapter2 6.
ThespecificadditionaleffectsidentifiedduringaCEFevent,isthewindspeedrequiredtogenerate thewaveeffectsduringthesitespecificPMF.Thepowerblockareaandstructuresbelowelevation 730.0ftareaffectedbytheCEF.ThewindgeneratedwavesassociatedwiththeCEFincreasetheflood heightaroundthepowerblockandtheintakestructure.Theonlyaffectedpowerblockstructureisthe Unit1TurbineBuilding.Thisbuildingisdesignedtofloodandfloodingcommenceswellbelow730.0ft bydesign.Otherpowerblockstructuresfloodedduringthisevent,discussedinNote3,areunaffected bywindgeneratedwaves.Nootherpowerblockstructuresforeitherunitareaffectedbywind generatedwaves,asthewavesbreakontheslopesapproachingthesebuildings.Thisincludesallother Unit1buildings,Unit2,theFLEXEquipmentStorageBuilding(FESB)andtheemergencyoutfallsystem (EOS).TheCEFwaveheightattheintakestructureisboundedbytheDB.
Thewindspeedassumedtogeneratethewavesisthe2yearmaxsustainedwindspeedof50mphper ANS2.81992.TheexistingDBwindgeneratedwavewindvelocityisasustainedwindof40mphfor approximately2hours.ThenewhazardwindspeedisslightlylargerthantheDBvaluebuttheoverall windspeedisnotexcessivelylargebeingthe2yearoccurrenceinterval.Thevalueisboundedbythe existingdesignbasiswindspeedsforthepowerblockstructuresandtheIntakestructure.An80mph fastestmilewindspeed,atanassumedelevationof30feet,isusedasthedesignwindvelocityto determinewindloadingsonSeismicCategoryIstructures.SincetheDBwindspeedvalue(40mph)for creationofwindgeneratedwavesislessthanthenewhazardwindspeed(50mph)itisconsidered notbounded.However,nonegativeimpacttoCategory1andnonCategory1structuresisanticipated basedonthiswindspeed.Also,AOP1/2.75.1ActsofNatureSevereWeatherwillbeenteredoncethe sustainedwindsreach>40mph.Nospecificactionsrelatedtothiseventaregivenorarewarranted.
PostHighWindeventactionsarecontainedintheprocedure.
References:
CalculationDSC6799,BVPS1UFSARsection2.3.8,2.3.8.1,2.3.8.3,2.3.8.4,ANS2.81992 7.
Thegroundwateratthesiteistypicallybelowallstructurebasematsexceptforstructureslocatedat theriversedge.GroundwateratthesitetypicallyisequivalenttotheOhioRiversurfaceelevation.
DuringaCEFeventtheOhioRiverwillrisetoaheightof730.0ft.Therefore,thegroundwaterwillrise accordinglycausingagroundwatersurcharge.Thesitefloodprotectedstructuresaredesignedfora PMFof730ftincludingtheresultantgroundwaterhydrostaticpressures.Thewaveactionwillcausea smallincreaseinthispressure;however,exceptfortheUnit1TurbineBuildingandtheIntake structure,nootherbuildingsaresubjecttothisincrease,astheyarenotsubjecttowaveaction.
Groundwaterwouldnotbesubjectedtothewindwaveenergyandwouldnotraiseabovethe730.0ft stillwaterelevation.TheremainingCategory1powerblockstructuresaredesignedforfloodlevelsup to730ftincludingtheresultantgroundwaterhydrostaticpressures.Therefore,itisbounded.
Page15of18
References:
References:
CalculationDSC6799,BVPS1UFSARSection2.3.2.3,2.3.2.1.2,5.2.2.5.1, BVPS2UFSARSection3.4,2.5.4.6,2.4.13.5 8.
TheUFSARdiscussesthePMFaswellasthepotentialforwindgeneratedwaves.TheUFSARstates thatthestationwillactasthewaterlevelrisestoandincludingnormalshutdownandcooldown.The LicenseRequirementsManualrequiresthisactionat700ftelevationintheOhioRiver.
ThesitewillenterAOP1/2.75.2ActsofNatureFloodat670ft.ThisAOPdirectsamultitudeof preparationactivities,includingmobilizingadditionalpersonneltobeonsite,andincreasesthe monitoringtimeastheriversrises.Theduelunitplantshutdownwillcommenceat695ftifflood predictionsabove700ftareindicated.TheCEFeventisslowdevelopingeventandtheunitswillbe shutdownwellinadvanceofthepeakoftheCEF.
DuetothemagnitudeofthestormrequiredtoproducethePMFsitepersonnelwouldbeawareofthe impedingfloodbeforetheriverlevelbeginstorise.BoththeUFSARdesignbasisAttachment2.3A, Plate4andtheFHRRUSACEhydrographsforthebasinwidePMFprovideapproximately3.25daysof warningandpreparationtimefrominceptionoftherainfallontothewatershedtothepeakflood elevation.SimilartimeframeswouldbeexpectedtoexistfortheNRCMSFHIletterfloodvalues.AOP 1/2.75.1ActsofNatureSevereWeatherwillbeenteredoncethesustainedwindsreach>40mph.No specificactionsrelatedtothiseventaregivenorarewarranted.PostHighWindeventactionsare containedintheprocedure.
Basedontheaboveandtheslowdevelopmentoftheevent,thisitemisconsideredbounded.
References:
CalculationDSC6799,FHRRSection4Table3,AOP75.1and75.2,BVPS1UFSARSection 2.3.3,Attachment2.3A,Plate4,Plate5,BVPS2UFSARSection10.4.5.3,2.4.15,2.4.10,2.4.3.6, 2.4.13.5,2.4.14,Figure2.47,Appendix2.4A,USACEHydrographs,LicenseRequirementsManualBasis B3.7.2 9.
SitePreparationisdiscussedinNote8.TheFloodAOPcontainsasignificantnumberofactionsbased onvariouswaterlevelelevationsintheOhioRiver.Asexamplestheseincludeclosingandsealingthe flooddoorsattheintakestructure,closingdoors,hatches,stagingpumpsetc.,aswellascallingin additionalstaff.Asdiscussedinnote10,theperiodofsiteinundationbeginsoncetheOhioRiver reaches690ft.Thisresultsinapproximately78hoursofsitepreparationtimepriortotheRiver reaching690ft.NoadditionalactionsareidentifiedfortheNRCMSFHIlettervalues.
ThisitemisconsideredboundedbasedonthediscussionsinNote8.
References:
CalculationDSC6799,FHRRSection4Table3,AOP1/275.1and75.2,BVPS1UFSAR.3A,Plate4,Plate5,BVPS2UFSARSection10.4.5.3,2.4.15,2.4.10,2.4.3.6,2.4.13.5, 2.4.14,Figure2.47,Appendix2.4A,USACEHydrographs 10.
Asdiscussedinthepreviousnotesthiseventisslowdevelopingandallowsforappropriate preparations.Forthisdiscussion,theperiodofinundationbeginsoncetheOhioRiverreaches690ft, andthenrecedesbacktothisvalue.Thisisanarbitrarilychosenvalue,whichis15feetbelowthe operatingdeckoftheIntakeStructureandlowestelevationsofthepowerblockarea,andwaschosen basedonavailabledesignbasisinformation.Thisresultsinapproximately100hoursoffloodingonsite perBVPS1UFSARAttachment2.3APlate5.TheFHRRUSACEhydrographsforthebasinwidePMF
Page16of18 providesthattheinundationlastsforabout74hoursabovethe690ftelevation.Thesiteflood protectionfeaturesarenotspecificallysensitivetoanysmalldifferenceofinundationtimes.Similar timeframeswouldbeexpectedtoexistfortheNRCMSFHIletterfloodvalues.Basedonthis,the inundationperiodisconsideredbounded.
References:
CalculationDSC6799,FHRRSection4Table3,AOP75.1and75.2,BVPS1UFSAR.3APlate4,Plate5,BVPS2UFSARFigure2.47,USACEHydrographs 11.
TheBVPS1UFSAR,Attachment2.3APlate2and4,showsapproximately70hoursforrecessionfrom thepeakPMFelevationof730fttoapproximately690ft.Thebulkofthesite,andthepowerblock areaisonlyfloodedforapproximately60hoursandthewaveactiononlycontrolstheoverallpeak nearthepeakofthestillwaterflood.TheFHRRUSACEhydrographsforthebasinwidePMFshows thatthepeakPMFelevationat690ftlastsforapproximately30hours.Thisisconsiderablyshorter, andthereforethisisconsideredbounded.
References:
CalculationDSC6799,BVPS1UFSARSection2.3.3,Attachment2.3APlate2,4,BVPS2 UFSARFigure2.47 12.
PlantmodesarediscussedintheUFSARrelatedtofloodingevents.Asthefloodwaterelevation increasesvariousactionsaretakenuptoandincludingmodechangetocoldshutdown.TheMSFHI doesnotdirectlyaddressplantmodesnordoestheFHRR.AsthePMFassociatedwithCEFwould requireactionsasdiscussedinNote8,plantmodeisconsideredbounded.
References:
CalculationDSC6799,BVPS2UFSARSection2.4.14,LicenseRequirementsManualBasisB 3.7.2,USACEHydrographs,Figure16,FHRR 13.
NoadditionalfactorswereidentifiedassociatedwiththeCEF.Sinceneitherthedesignbasisnorthe MSFHIidentifiedanyadditionalfactors,thisisconsideredbounded.
References:
CalculationDSC6799,FHRR,BVPS-1andBVPS2UFSARChapters2and3
Page17of18
2.3NEI1206,Rev.2,SectionG.4-EvaluationofMitigatingStrategiesfortheMSFHI
2.3.1.NEI1206,Rev.2,SectionG.4.1-AssessmentofCurrentFLEXStrategies TheoverallplantFLEXresponsestrategiestoanELAPorLUHSeventcanbe implementedasdescribedintheFinalImplementationPlanusingcurrentprocedures, equipmentandpersonnel,pendingthecompletionofthefloodhazardmitigation modification(discussedbelow).
2.3.1.1Conclusion-ModifyFLEX
2.3.2NEI1206,Rev.2,SectionG.4.2-AssessmentforModifyingFLEXStrategies Theassessmentconcludedthatthefloodcausingmechanismswouldnotinitiatean ELAPorLUHSevent,withthecompletionofaminorfloodhazardsmitigation modification.FLEXactivitieswouldbeinitiatedthroughexistingplantproceduresfor abnormaloremergencyeventresponse.Theindividualfloodingmechanismswere evaluatedassumingtheycouldoccuratanypointontheFLEXstrategytimelineto ensurethatthemostseverefloodingwouldbeevaluatedatatime,whichwouldhave themostadverseimpactonFLEXimplementation.Theassessmentincluded evaluationofFLEXequipmentstorageareas,operationsandstaginglocations, deploymenttravelpaths,andtheworkingconditionsforpersonnelandequipmentin floodedareas.
TheassessmentconcludedthattheMSFHIwouldnotpreventFLEXimplementationfor theCEFevent.ThemaximumreevaluatedstillwatersurfaceelevationoftheOhio Riverwasdeterminedtobe730.0ft,whichisequaltothecurrentdesignbasis.Wind generatedwaverunupatvariouslocationsexceedsthecurrentdesignbasisvalue:
732.8ftattheUnit1TurbineBuildingNorthwall.
734.0ftatthegroundslopeapproachingUnit2ReactorBuilding.
734.5ftatthegroundslopeapproachingtheEmergencyOutfallStructure(EOS).
TheUnit1TurbineBuildingwillflood(perdesign);however,therewillbenowave effectsontheadjacentfloodbarrier(ServiceBuildingnorthwall).TheWSEwillbe withinthedesignbasisvalueof730.0ft.ThewaveactionapproachingtheUnit2 PowerBlock(ReactorBuilding)andtheEmergencyOutfallStructurelocationis maintainedonthegroundslopesapproachingthestructuresandthereforehasno impactonthesafetyrelatedstructures.TheassessmentconcludedthattheFLEX strategiesincludesufficientmarginandflexibilitysuchthatsuccessfulimplementation isachievablewiththeincreasedfloodinginthevariousareas.
FortheLIPevent,theassessmentconcludedthattheMSFHIcouldpotentiallyaffect FLEXstrategiesduetofloodingofinternalUnit1areaswhenopeningadoortosupport FLEXspentfuelpoolactivities.Installingafloodbarrierwillmitigatetheadverse effects.AllotherFLEXstrategiesincludesufficientmarginandflexibilitysuchthat successfulimplementationisachievablewiththeincreasedflooding.
Theactionsidentifiedbelowarerequiredtomitigatetheeffectsofthebeyonddesign basisfloodeventassuringtherewillbenoadverseeffectsonFLEXstrategy implementation.
Page18of18
- a.
TomitigatethepotentialLIPflooding,installaremovablefloodbarrier ondoor1F353(EngineeringChangePackage15357003).
- b.
Revise,asrequired,FLEXSupportGuidelinesandAttachmentsforUnit1 FLEXimplementationtoidentifytherequirementforbarrierinstallation ondoor1F353whendoor1F352isopenedforFLEXimplementation.
Theactionsidentifiedabovewillbetrackedinthesitecorrectiveaction program(ConditionReport201709202).
2.3.2.1Conclusion TheMSAdemonstratedthatwiththeinstallationofanewfloodprotectionfeature, theFLEXstrategies,asdescribedintheFIP,areacceptable.
TheboundaryconditionsandassumptionsoftheinitialFLEXdesignare maintained.
ThesequenceofeventsfortheFLEXstrategiesisnotaffectedbytheimpactsof theMSFHI(includingimpactsduetotheenvironmentalconditionscreatedby theMSFHI)insuchawaythattheFLEXstrategiescannotbeimplementedas currentlydeveloped.
ThevalidationperformedforthedeploymentoftheFLEXstrategiesisnot affectedbytheimpactsoftheMSFHI.
ThedeploymentlocationsofFLEXequipmentareshowntobeacceptable.
TherearenonewormodifiedactionsrequiredfortheFLEXstrategies,except foridentifyingthepotentialinstallationofadoorfloodbarrier.
Thefloodprotectionfeaturesmeetallperformancecriteriaspecified.
2.4References FHRR,Rev.0,2/4/2016-10CFR50.54(f),RegardingtheFloodingAspectsofRecommendation 2.1oftheNearTermTaskForce(NTTF)ReviewofInsightsfromtheFukushimaDaiichi Accident.
NRCcorrespondenceLetterML17040A011,withEnclosureML17039A550-Dated 2/22/2017,BeaverValleyPowerStation,Units1and2InterimStaffResponseTo ReevaluatedFloodHazardsSubmittedInResponseTo10CFR50.54(f)Information RequestFloodCausingMechanismReevaluation.
NORMLP7121,BeaverValleyPowerStationFloodingMitigatingStrategyAssessment SupportDocument.
BeaverValleyPowerStationBVPS1UFSARRev.29 BeaverValleyPowerStationBVPS2UFSARRev.22 CalculationDSC6794EffectsofLocalIntensePrecipitationAnalysis CalculationDSC6799CoincidentWindWaveAnalysis EnerconReportFNOCBV060REPT001 CalculationDSC0368BDBLIPInternalEffectsAnalysis DrawingRE37A,SleevesandOpenings 1/2OM53C.4A.75.1ActsofNatureSevereWeather(AOP75.1) 1/2OM53C.4A.75.2ActsofNatureFlood(AOP75.2)
LicenseRequirementsManualBasisB3.7.2,FloodProtection ConditionReport201709202,FloodingMitigatingStrategyIdentifiedOneAreaofConcern withtheFLEXStrategy