ML12332A072

Southern California Edison'S Flooding Walkdown Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ic

ML12332A072
Person / Time
Site:	San Onofre
Issue date:	11/26/2012
From:	Bauder D R Southern California Edison Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
Download: ML12332A072 (23)

Text

i.i;i l fD RI50 RN'A n E DISO N I NT ER N AT IO NALCompany U.S.Nuclear Regulatory Commiss ion Attn: DocumentControlDesk Washington

,D.C.20555 Novembe r 26, 2012 Dougla s R.Bauder Sit e Vice Pre sident&Station Manager S an OnofreNuclearG e n erating Station1OCFR50.54(f)

Subject:

DocketNos.50-361and50-362 Southern California Edison's Flooding Walkdown ResponsetoNRC Request for Information Pursuantto10 CFR 50.54(f)Regarding the Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident.References

1)NRCLetter

,Requestfor Information PursuanttoTitle10oftheCodeof Federal Regulations 50.54(f)Regarding Recommendat ions 2.1 , 2.3 ,and9.3 ,oftheNear-TermTaskForceReviewofInsightsfromthe FukushimaDai-ichiAccident,datedMarch12,2012.2)NRCLetter, Endorsement of NuclearEnergyInstitute(NEI)12-07,"GuidelinesforPerforming Verification WalkdownsofPlantFloodProtectionFeatures

",datedMay31

,2012.

DearSirorMadam:

OnMarch12 ,2012 ,theNRCissued Reference1toallpowerreactor licensees andholdersof construction permits inactiveordeferredstatus.

Enclosure4of Reference 1 contains specificRequestedActions

,RequestedInformation ,and Required Responses associated with Recommendation2.3forFlooding Walkdowns.

Specifically, Enclosure 4 of Reference1statesthatwithin180daysoftheNRC's endorsementofthe walkdown process , each addressee will submititsfinalresponse

,includingalistofanyareasthatareunabletobeinspecteddueto inaccessibilityanda scheduleforwhenthe walkdownwillbe completed.

Enclosure2tothisletter containsSouthernCalifornia Edison's flooding walkdownresponseforSanOnofre Nuclear GeneratingStation(SONGS)Units2and3

, consistentwiththe NRC-endorsed guidance (Reference 2).Thisletter contains regulatory commitments.

The specific regulatory commitments and the scheduledduedatefor completionareidentifiedinEnclosure1ofthisletter.Shouldyouhaveany questions concerning the contentofthisletter

, please contact Licensing Manager ,LindaConklin

,at(949)368-9443.

P.O.Bo x 128 S a n C lemen te , CA 92672 (9 49)368-9275 PAX 89275 Fax: (949)368-9881 D o u g.Baude r@sce.com Document Control Desk-2-November 26, 2012 I declare under penalty of perjurythatthe foregoingistrueandcorrect.

Executed on II/CD (;J-()(:L.Douglas R.Bauder Site Vice President and Station Manager cc wI encl: Director, Office of Nuclear Reactor RegulationE.E.Collins, Regional Administrator,NRCRegionIVG.G.Warnick , NRC Senior Resident Inspector, San OnofreUnits2and3R.Hall,NRC Project Manager, San OnofreUnits2and3B.Benney,NRC Project Manager, San OnofreUnits2and3 Enclosure 1

List of Commitments and Schedule for Implementation of Flooding Walkdown Results

This table identifies actions discussed in this letter for which Southern California Edison commits to perform. Any other actions discussed in this submittal are described for the NRC's information and are not commitments.

Commitment Action Type Scheduled Due Date One-Time Sustainable Complete inspection of all restricted access features as identified in the SONGS Flood Walkdown Report X 07/01/2013 Resolve deficiencies as identified in the SONGS Flood Walkdown Report X 07/01/2013

Enclosure 2:

San Onofre Nuclear Generating Station Flood Walkdown Report

San Onofre Nuclear Generating Station Flood Walkdown Report Fukushima Near-TermTaskForce-Section2.3, Flooding Walkdowns NN 201899774 November 2012PeparedBy:

Southern CaliforniaEdisonandCH2MHILL Contents I SONGSFloodWalkdownReport..........................................................................................................................1Introduction...............................................................................................................................

.......................1Purpose...............................................................................................................................

..............................1RequestedContent...............................................................................................................................

............1SectionA:DesignBasisFloodHazardLevel(s).....................................................................................1SectionB:ProtectionMitigationFeaturesConsideredintheLicensingBasis....................................5SectionC:WarningSystemstoDetectthePresenceofWater...........................................................7SectionD:EffectivenessofFlood ProtectionFeatures.......................................................................8SectionE:ImplementationoftheWalkdownProcess........................................................................9SectionF:ResultsoftheFloodFeatureWalkdown...........................................................................10SectionG:Cliff EdgeEffects..............................................................................................................16SectionH:OtherPlannedand/orNewlyInstalledFloodProtectionFeaturesorMeasures............16Conclusion...............................................................................................................................

........................16Deficiencies...............................................................................................................................

.........16Restricted AccessFloodFeatures......................................................................................................17InaccessibleFloodFeatures...............................................................................................................17References...............................................................................................................................

.......................17ExhibitsE 1SONGSFloodFeatureWalkdownTeamComposition....................................................................................10 1 SONGS Flood Walkdown Report Introduction InresponsetothenuclearfueldamageatFukushimaDai Ichipowerfacilityresultingfromanearthquakeandsubsequenttsunami,theUnitedStatesNuclearRegulatoryCommission(NRC)requestedinformationpursuanttoTitle10oftheCodeofFederalRegulations(10CFR),Section50.54(f).Aspartofthisrequest,SouthernCaliforniaEdison'sSanOnofreNuclearGeneratingStation(SONGS)wasrequiredtoperformfloodfeaturewalkdownstofield verifythatplantfeaturescreditedinthecurrentlicensingbasis(CLB)forprotectionandmitigationfromexternalfloodeventsareavailable,functional,andproperlymaintained[1]. Purpose Thisdocumentprovidesasummaryofthefieldassessmentofexternalflood protectionandmitigationcapabilitiesinaccordancewithNRCRecommendation2.3ofSECY11 0137[2]andEnclosure4oftheMarch12,2012,RequestforInformationPursuanttoTitle10CFR50.54(f)RegardingRecommendations2.1,2.3,and9.3,oftheNearTermTaskForceReviewofInsightsfromtheFukushimaDai IchiAccident(50.54(f)letter[3]).TheSONGSfloodprotectionwalkdownwasdesignedtoverifythatpermanentand/ortemporarystructures,systems,components(SSCs),andproceduresneededduringafloodeventareacceptableandcapableofperformingtheirdesignfunctionascreditedintheCLB.Thewalkdownalsoservedasameanstoverifyvisuallythatplantmodificationsimplementedsinceoriginalconstruction,suchassecuritybarrierinstallations,donotadverselyaffectplantfloodingprotection[1]. Requested Content AsspecifiedintheNRC endorsedNuclearEnergyInstitute(NEI)12 07[Rev.0]GuidelinesforPerformingVerificationWalkdownsofPlantFloodProtectionFeatures(NEI12 07[1]),AppendixDprovidesadditionalinformationonthespecificinformationrequestsinEnclosure4oftheNRC'sMarch12,2012,50.54(f)letter.Eightsectionswereidentifiedasrequiringresponse;thesecanbefoundbelowinSectionsAthroughH. Section A: Design Basis Flood Hazard Level(s)

Requested Information Describethedesignbasisfloodhazardlevel(s)forallflood causingmechanisms,includinggroundwateringress. SONGS Response TheSONGSsiteislocatedonthesouthernCaliforniacoastoftheUnitedStatesonthePacificOceanandissituatedonacoastalplainatthebaseofthewesternfoothillsoftheSantaMargaritaMountainRange.Therearenoperennialstreamsinthegeneralvicinityoftheplantsite.Thepowerblockfinishgradeelevationis+30.0feetmeanlowerlowwater(mllw),whichisbasedontheplant'sbenchmark1977referenceelevation[4].Themeanannualtemperatureinthecoastalplainregionis61 F,withameanminimumtemperatureof42 FinJanuary.Annualrainfallrangesfrom10to16inches,with90percentoftheannualtotaloccurringduringthemonthsofNovemberthroughApril[4].

SONGS FLOOD WALKDOWN REPORT 2 Descriptionsofthedesignbasisfloodhazardlevel(s)forallflood causingmechanisms,includinggroundwateringress,aredetailedintheSanOnofre2&3UpdatedFinalSafetyAnalysisReport(UFSAR)[4],Section2.4.AdditionalinformationfromotherCLBdocumentsisreferencedasneeded.ThefollowingsubsectionsprovidetheinformationrequestedbytheNRCforeachflood causingmechanismasdetailedinthecurrentlicensingbasisdocuments.Inaseparateactivity,SONGSisperforminganexternalfloodhazardreevaluationaspartofaresponsetoSECY11 0137Item2.1ofthe50.54(f)letterrequestforinformation,whichwillevaluatethecurrentlicensingbasis.LocalIntensePrecipitation(DesignBasisFloodHazard).The6hour,1 square mileprobablemaximumprecipitation(PMP)eventcausesthehighestfloodlevelontheSONGSsiteandisthereforeusedasthedesignbasisfloodevent[4].ThevolumeofthePMPwas7inchesin1hourand12.25inchesin6hours.MaximumPostulatedPMPFloodElevation.ThemaximumpostulatedPMPfloodelevationis+31.0feetmllwintheSONGSUnit2andUnit3PowerBlock[4].KeyAssumptions.Allcatchbasinsforthesubsurfacedrainagesystem,roofdrains,andexposedfloordrainsareassumedpluggedforthepurposeofdeterminingwatersurfaceelevationsarisingduringthethunderstormPMPevent[4].MethodologyUsedtoDeveloptheDesignBasisFloodingHazard.U.S.WeatherBureauHydrometeorologicalReport(HMR)36[5]wasusedtocalculatetheorographicandconveyancecomponentsofthefrontalPMP.EvaluationofthePMPwasalsodeterminedfortheSONGSsitebasedonthemethodsoftheU.S.WeatherBureau.Thedistributionofprecipitationinthe6 hourthunderstormwascalculated;arrangementoftheincrementalvaluesintothecriticalPMPstormwasbasedonproceduresusedbytheU.S.ArmyCorpsofEngineers.ThedrainageareatributarytotheSONGSUnit2andUnit3powerblockwasdividedintosubbasins.TheU.S.SoilConservationServicesoilcomplexmethodwasusedtoconstructthehydrographresultingfromthePMP.RunoffcurvesforthegivensoiltypeswereselectedonthebasisofAntecedentMoistureConditionIII.Duetotherelativelyshorttimesofconcentrationandcorrespondingveryshortlagtimesofthesubbasins,theassumptionwasmadethatallprecipitationexcesswithinanyperiodbecamerunoffduringthatperiod.Precipitationintensitiesfordurationslessthan15minuteswereinterpolatedfromthethunderstormPMPdata[4].DifferencesorContradictionsinFloodHazardLevels.Nodifferencesorcontradictionsinthefloodhazardlevelswereidentifiedindesignorlicensingdocumentation.ProbableMaximumFlood(PMF)onStreamsandRivers.Ananalysisofthe43 square mileSanOnofreCreekBasin(northofthesite)andthe0.86 square mileFoothillDrainageBasin(eastofthesite)wasconductedtodeterminethePMFandsubsequentcontributiontofloodingattheSONGSsite.RecommendationsofNRCRegulatoryGuide1.59wereusedinconductingthePMFanalysis[4].MaximumPostulatedPMFFloodElevation.SanOnofreCreekBasin-ThePMFpeakdischargeof71,000cubicfeetpersecond(ft 3/s)wasusedindeterminingthemaximumfloodstageinSanOnofreCreek.TheresultsoftheanalysisdemonstratedthattheflowwouldbecontainedwithinthelimitsofthefloodplainofSanOnofreCreekandwouldnotpresentanyriskoffloodingatthesite[4].FoothillDrainageBasin-PMPinducedrunoffisdivertedtotheSanOnofreCreekbyadiversionstructure.Thediversionstructureconsistsofanearth filledbermwithanexcavatedchanneldesignedtointerceptandconveythepeakdischargeassociatedwiththePMF.Theresultsoftheanalysisshowedthattheflowwouldbecontainedwithinthelimitsofthediversionstructureandwouldnotpresentanyriskoffloodingatthesite.[4].KeyAssumptions.DuringthePMFanalysis,thesoilwasconsideredsaturated.ASnyderpeakingcoefficientof0.7wasusedforunithydrographcomputations.TheMuskingumstoragecoefficientKforeachreachwastakenas50percentofthebasin'slagtime.TheroutingcoefficientXwasassumedas0.3[4].

SONGS FLOOD WALKDOWN REPORT 3 MethodologyUsedtoDeveloptheDesignBasisFloodingHazard.TheSanOnofreareaissusceptibletofrontalstorms,usuallyoccurringduringthemonthsofOctoberthroughApril,andlocalthunderstorms,whicharepredominantduringsummerandearlyfall.ThePMPvaluesassociatedwithbothtypesofstormswerecomparedtodeterminethecriticalevent.HMR36wasusedtocalculatethefrontalstormPMPandtheNationalWeatherServiceReportwasusedindeterminingthethunderstormPMP.Itwasconcludedthe6 hour,1 square milethunderstormPMP(12.25inches)wasthemorecriticalandconsequentlywasusedasthedesignbasisevent[4].SanOnofreCreekBasin:TheSanOnofreCreekBasinwassubdividedandhydrologicparametersforeachsubbasinwerecalculated.ThesubbasinlagtimeswerecalculatedonthebasisofafigurepublishedbytheU.S.ArmyCorpsofEngineers.ThisbasinlagcurvewasderivedasaresultofastudyofvariousdrainagebasinsinsouthernCaliforniaconductedbytheU.S.ArmyCorpsofEngineers.Forpurposesofconservatism,a10percentreductionofallcalculatedlagtimeswasperformedpriortotheiruseincalculations.UsingtheU.S.ArmyCorpsofEngineersHEC 1computerprogram,thePMFhydrographforeachsubbasinwasderived.ASnyderpeakingcoefficientof0.7wasusedforunithydrographcomputationsintheprogramforeachsubbasin.ThisvaluewasdeterminedasaresultoftheanalysisofthemajorstormsofJanuaryandFebruary1969,asreferencedinSanOnofre2&3UFSARSection2.4.3.2[4].Asnoted,theanalysiswasperformedfortheSantaMargaritaRiverBasin,whererecordspermittedavalidreconstructionofthebasinrunoffhydrograph.AfterdeterminingthePMFhydrographforeachindividualsubbasin,thehydrographswereroutedandcombinedtoobtainaPMFhydrographatthemouthofSanOnofreCreek.FloodroutingwasconductedusingtheMuskingumMethod.TheMuskingumstoragecoefficientKforeachreachwastakenas50percentofthebasin'slagtime.Thecoefficientvaluewasdeterminedbyassuminglow flowandhigh flowconditionsinsubbasinA5andcalculatingthecorrespondingvelocitiesandaverageflowvelocity.Theaveragevelocitywascombinedwiththereachlengthtoyieldthetraveltimethroughthereach.Fromthisrelationship,aproportionalityconstantwascalculated(i.e.,0.5)andthenusedincalculatingKfortheremainingsubbasins.TheroutingcoefficientXwasassumedas0.3,whichisusedformountainousregions[4].FoothillDrainageBasin:TheanalysisoftheFoothillDrainageBasinwasconductedinamannersimilartothatofSanOnofreCreekBasindescribedabove.Thedrainageareawassubdividedandsubbasinhydrologicparametersweredefined.TheHEC 1computerprogramwasusedtodeveloptheunithydrographandresultantPMFhydrographforeachsubbasin.AsexplainedinSanOnofre2&3UFSARSection2.4.3.3.1[4],aSnyderpeakingcoefficientvalueof0.7wasusedtoderivetheunithydrographs.ThePMFhydrographsobtainedfromeachsubbasinwereroutedtoSanOnofreCreek.DuetotherelativelyshortdistancebetweentheoutletsofsubbasinsB1andB2,approximately0.75mile,andnarrowrangeoflagtimesforthesubbasins,itwasdecidedtoignorelagandtraveltimesandcombinetheindividualsubbasinPMFhydrographsdirectly,yieldingaconservativePMFhydrographattheoutletofsubbasinB2[4].DifferencesorContradictionsinFloodHazardLevels.Nodifferencesorcontradictionsinthefloodhazardlevelswereidentifiedindesignorlicensingdocumentation.PotentialDamFailures.Therearenoexistingdamslocatedwithinthevicinityoftheplantsitewhoseseismicallyinducedfailurecouldresultinadversefloodingatthesite[4].ProbableMaximumSurgeandSeicheFlooding.MaximumPostulatedSurgeandSeicheFloodElevation.Theworststormgeneratedwaveof54feetwouldbegintobeaffectedbytheoceanflooratadistanceoffshoreofapproximately11,000feetandwouldbecompletelydissipatedbythetimeitreachedthebeachinfrontoftheSanOnofreseawall.Themaximumstormsurgeheighthasbeendeterminedtobe+1.98feetabovetheantecedentwaterlevel.It SONGS FLOOD WALKDOWN REPORT 4 wasconcludedintheSanOnofre2&3UFSARthatlargesurgeswillnotdevelopinthevicinityofSanOnofre.Seichehasbeenfoundtoaffectseasurfaceelevationbyonly0.7centimeter,whichisconsiderednegligible.[4].KeyAssumptions.ThemostconservativevalueswereselectedfortheprobablemaximumsurgeandseichefloodingcalculationandaredetailedintheSanOnofre2&3UFSAR,Section2.4.5[4].MethodologyUsedtoDeveloptheDesignBasisFloodingHazard.1. ProbableMaximumWindsandAssociatedMeteorologicalParameters-UsingtheclimatologyofthenortheastPacifictropicalcyclonesandthestructureoftypicalhurricanes,thetrackandthesurfacewindstructureofthehypotheticalmaximumprobablestormfortheSONGSsitewereconstructed.2. SurgeandSeicheWaterLevels-Waterlevelsantecedenttoprobablesurgeandseichelevelswereestablished.AcceptedconservativehightidelevelsandsealevelanomaliesfortheSanOnofreareawereconsideredinestablishingtheantecedentwaterlevels.Themaximumsurgewaterlevelhypotheticallypossibleandapplicabletothesitewouldresultfromthehypotheticalmaximumprobablestorm.Indevelopingthehypotheticalmaximumtropicalstorm,particularattentionwasgiventotheconfigurationofitsradiusofmaximumwinds,thestorm'sforwardspeed,andthestorm'strack.Detailedmeasurementsandanalysesoflong periodwaves(normalshelfseichingbackgroundlevels)overthecontinentalborderlandwereconductednearOceanside,California,about17milessoutheastofSanOnofre,andusedfordeterminationofseichewaterlevels.3. WaveAction-Severedeep waterstormwavesdeterminethelowestandhighestinstantaneouswaterelevationsinconjunctionwithlongperiodphenomena(e.g.,tideandstormsurge).Asseverewavesareinfrequent,itwasnecessarytodeterminetheircharacteristicsbyhindcasting.Acarefulselectionofpaststormsbasedonreportedwavedamageandstrongwindswasconducted.Then,thedeep watersignificantwavecharacteristicsforeachstormweredeterminedfromweathermaps.Awaveheightdistributionfunctionwasusedtodeterminethehighestindividualshallow waterwaveheight,H max ,inthestormfromthehindcastedsignificantwaveheightandperiodtimehistories.MarineAdvisorsandInterseaResearchexaminedatotalofapproximately60stormsthatoccurredbetween1900and1967andthatoccurrednearenoughtoSanOnofretobeappliedtothisstudy.Twenty fiveofthemostseverestormswereselectedforhindcasting.Thedeep waterwavedatawerecorrectedforrefractionandshoalingattheSONGSsite,andalsoforislandsheltering[4].DifferencesorContradictionsinFloodHazardLevels.Nodifferencesorcontradictionsinthefloodhazardlevelswereidentifiedindesignorlicensingdocumentation.ProbableMaximumTsunami(PMT)Flooding.ThepotentialfloodingeffectsfrombothlocallygeneratedanddistantlygeneratedtsunamiswereanalyzedfortheSONGSsite.Thelocallygeneratedtsunamiwasfoundtoproduceagreaterwaverunupthanthedistantlygeneratedtsunami.Therefore,thelocallygeneratedtsunamiresultsinthedesignbasisfortheSONGSsite.MaximumPostulatedPMTFloodElevation.Thecontrollingtsunamioccurringduringsimultaneoushightideandstormsurgeproducesamaximumrunuptoelevation+15.6feetmllwattheSONGSUnit2andUnit3seawall.Whenstormwavesaresuperimposed,thepredictedmaximumrunupistoelevation+27feetmllw[4].KeyAssumptions.Mathematicalmodelingofthehypotheticaltsunamiwasconductedassuminganearthquakewitha7 footverticaldisplacementcomponentoftheseafloor5milesoffshorefromSanOnofreasthegeneratingmechanism.NormalfaultingwaspostulatedforthehypothesizedoffshoreZoneofDeformationbecausetheconversionoflargestrike slipmovementsontheseafloortoatsunamiwavenearSanOnofrewouldbeinefficient[4].MethodologyUsedtoDeveloptheDesignBasisFloodingHazard.BecauseofthemoderatingeffectofsouthernCalifornia'soffshoreborderlandondistanttsunamiwaves,localoffshorefaultzonesareconsideredtobethemostprobablegeneratorsforlargewavesatSanOnofre.Theclosestsuchzonetothe SONGS FLOOD WALKDOWN REPORT 5 SONGSsiteisthehypothesizedoffshoreZoneofDeformation,asdiscussedinSanOnofre2&3UFSARSection2.5.2.4.5[4].Theclosestportionofthiszoneisapproximately5milessouthwestoftheSONGSsite.TostudytheeffectatSanOnofrecausedbyseafloordisplacementsontheoffshoreZoneofDeformation,detailedspecificanalyseswerecompletedbyDr.BasilW.Wilson[6].Mathematicalmodelingofthehypotheticaltsunamiwasconductedassuminganearthquakewitha7 footverticaldisplacementcomponentoftheseafloor5milesoffshorefromSanOnofreasthegeneratingmechanism.ThisverticaldisplacementismuchlargerthanwouldbeexpectedtooccuronthehypothesizedoffshoreZoneofDeformation,which,becauseofitsnorthwesttrend,ischaracterizedbypredominantlystrike slipdisplacement.NormalfaultingwaspostulatedforthehypothesizedoffshoreZoneofDeformationbecausetheconversionoflargestrikeslipmovementsontheseafloortoatsunamiwavenearSanOnofrewouldbeinefficient.Further,therearenolargetopographicfeaturesorientednormaltothedirectionofstrike slipmovementontheoffshoreZoneofDeformation[4].DifferencesorContradictionsinFloodHazardLevels.Nodifferencesorcontradictionsinthefloodhazardlevelswereidentifiedindesignorlicensingdocumentation.GroundwaterIngress.MaximumGroundwaterElevation.Theaveragegroundwaterelevationbeneaththesiteis+5feetmllw.FluctuationswithinthepumpedregionsoftheSanOnofreCreekBasinhavehadlittleimpactonthelevelofgroundwaterattheSONGSsitebecauseofitsproximitytotheshoreline.MonitoringofgroundwaterlevelsattheSONGSsitefora10 yearperiodbetween1963and1974showedthewatertabletovaryfrom+2.7feetto+5.7feetmllwinthevicinityofthecontainmentspheres[4].KeyAssumptions.AsdiscussedintheSanOnofre2&3UFSARSection3.4.1.1.1[4],thefoundationbasematsandexteriorwallsofthestructuresthatofferfloodprotectionaredesignedtoresisttheupwardandlateralpressurescausedbythehydrostaticgroundwaterleveldesignbasiselevationof+5feetmllw.DifferencesorContradictionsinFloodHazardLevels.Nodifferencesorcontradictionsinthefloodhazardlevelswereidentifiedindesignorlicensingdocumentation.FloodingHazardsthatScreenedOut.Thefollowingfloodmechanismswerenotconsideredcredibleeventsandwerescreenedout: Ice InducedFlooding.Themildclimateandgenerallackoffreezingtemperaturesinthisregionmakeiceformationhighlyunlikelyanditis,therefore,notconsideredcredible. ChannelMigrationandDiversion.Upstreamdiversionsassociatedwithrivers,wherelowflowhasanimpactondependablecoolingwatersources,isnotafactorattheSanOnofresite. DamBreachandFailures.TherearenoupstreamdamsthatcouldimpacttheSanOnofresite. Section B: Protection Mitigation Features Considered in the Licensing Basis Requested Information DescribeprotectionandmitigationfeaturesthatareconsideredinthelicensingbasisevaluationtoprotectagainstexternalingressofwaterintoSSCsimportanttosafety. SONGS Response Thesafety relatedsystemsandcomponentsforwhichfloodprotectionisprovidedarethesameasthoseidentifiedinparagraphC.IofRegulatoryGuide1.29.Externalfloodprotectionofsafety relatedsystemsand SONGS FLOOD WALKDOWN REPORT 6 componentsisprovidedforallpostulatedfloodlevelsandconditionsdescribedinSanOnofre2&3UFSARSection2.4[4].DescriptionsoftheprotectionandmitigationfeaturesthatareconsideredinthelicensingbasisevaluationtoprotectagainstexternalingressofwaterintoSSCsimportanttosafetyaredetailedintheSanOnofre2&3UFSARSections2.4and3.4[4].FloodingLicensingBasis.ThePMFeventisapplicabletoallmodesofoperation(e.g.,full poweroperations,reducedpoweroperations,startup,hotshutdown,coldshutdown,andrefueling).The6 hour,1 squaremilePMPeventwouldcausethehighestfloodlevelontheSONGSsiteandisthereforeusedasthedesignbasisfloodevent.ThemaximumpostulatedfloodlevelintheSONGSUnit2andUnit3powerblockisbelowelevation+31.0feetmllw[4].FloodDurationAssumedintheCLB.Thedurationofthedesignbasisfloodeventisdefinedas6hours.Themaximumpostulatedfloodlevelisbasedona12.25 inch,6 hourPMPevent[4].FloodProtectionFeaturesthatareCreditedintheCLB.IncorporatedorExteriorPassiveFloodProtectionFeatures.1. Watercontrolstructuresconsistofthe42 inchand72 inch diameterconcreteculvertsunderInterstate5.TheculvertsaremaintainedbytheCaliforniaStateDepartmentofTransportation.Thecapacityoftheseculvertsis180and520ft 3/s,respectively.2. TheSanOnofreCreekdiversionstructurelocatedalongtheeastsideofInterstate5divertsrunofffromtheFoothillDrainageBasintoSanOnofreCreekBasin.Thecapacityofthechannelis1,850ft 3/s.3. Two4 footby4 footboxculvertsatHighway101remainoperational.Theboxculvertsaresufficientlylargeandinanareathatwouldnotsupplymaterialscapableofrestrictingflow.Evenifflowwererestricted,thetopographyalongHighway101issuchthattheresultingdrainageflowswouldnotimpacttheplantsite.4. Theswitchyardhasanupperandlowerbench.Withthenormalcatchbasinsplugged,thepondedwaterontheupperbenchwoulddraintothesouthaccessroad(nearSONGSUnit3).5. Withthenormalcatchbasinsplugged,theuppersiteareawoulddrainintothebarrancaassociatedwiththesouthaccessroad.6. AdiversionchannelatthesouthentrancetotheUnit3powerblockonthesouthsideoftheServiceBuildingdivertsrunofffromtheswitchyardanduppersiteareaovertheseawalloutsideofthepowerblock.7. Swalesareprovidedintheasphaltareasaroundthepowerblocktoconveythedrainagetotheseawall,whereitwilldischargetotheocean.8. Penetrationsintheauxiliarybuildingcontrolareaatelevations30and72feetmllwareprotectedagainstpondingresultingfromroofdrainagebyopeningsintheseismicgap,whichallowthewatertofalltoelevation7feetintheturbinebuildingarea.Theroofdrainagecontributingtotheturbinebuildingareaisfromthesafetyequipmentbuilding,theauxiliarybuilding,andtheturbineareas.9. Tunnelsandopeningsbetweenbuildingsaresealedbywaterstops.10. Surfacewaterwillnotentertheauxiliarybuildingfromthewestbecausethebridgewalkwayovertheintakestructurehasnumerousparapetopeningsthatallowdrainagetoflowintothecoolingwaterintakestructure.11. Aconcretebermonthewestsideofthebridgewalkwaypreventsthecontrolroomcomplexfromfloodingduetoapossiblesurgeinthecirculatingwatersystem.

SONGS FLOOD WALKDOWN REPORT 7 12. StormdrainageintheNorthIndustrialAreawillnotflowtoSONGSUnit2andUnit3becauseofanelevationdifferential;theNorthIndustrialAreaisatanelevationof20feetandSONGSUnit2andUnit3areatanelevationof30feet.AlthoughtheNorthIndustrialAreaaccessroadconnectstotheaccessroadfortheUnit2andUnit3switchyard,theNorthIndustrialAreaaccessroadisgradedtoprecludedrainageflowsfromenteringtheSONGSsite.13. Specialstructuresdesignedtoprotectthesiteagainstwaveactionincludetheseawallandthescreenwellperimeterwall.Theonshoreintakestructureisarrangedsothatallpenetrations,exceptinthescreenwell,aresealedagainstleakageofrisingorsurgingseawater.14. Thefloodprotectionofallpenetrationsofsafety relatedstructuresthatarebelowthemaximumpostulatedfloodlevel(+31.0feetmllw)aretabulatedinSanOnofre2&3UFSARTable3.4 1[4].IncorporatedorExteriorActiveFloodProtectionFeatures.1. WatertightandNonwatertightDoors-Thefloodprotectionofallexterioropeningsofsafety relatedstructuresbywatertightandnonwatertightdoorsthatarebelowthemaximumpostulatedfloodlevel(+31.0feetmllw)aretabulatedinSanOnofre2&3UFSARTable3.4 1[4].2. FloodSensors-Safetyrelatedareashavefloodlevelalarmsthatindicateinthecontrolroom.WeatherConditionsorFloodLevelsthatTriggerProceduresandAssociatedActionsforProvidingFloodProtectionandMitigation.TheSanOnofreAbnormalOperatingInstructionforSevereWeatherprovidesactionstominimizetheeffectofhurricanes,tornados,flooding,ortsunamisonthesafeoperationofSONGSUnit2andUnit3.Weatherconditionsconcerningexternalfloodingthattriggerthisprocedureincludethefollowing:flashfloodwatchorwarningoraheavyrainfallinprogress(rainfallisexpectedtoexceed3inchesina1 hourperiodor6inchesina3 hourperiod),andtsunamiwarning.Notificationsourcesareprovidedintheoperatingprocedure.TheassociatedactionsforprovidingfloodprotectionandmitigationaredetailedintheattachmentstotheAbnormalOperatingInstructionforSevereWeatherforflashfloodwatchorwarningandtsunamiwarning.ASanOnofreAlarmResponseInstructionprovidesoperatingpersonnelwithavailableoptionsorpossibilitiesfordealingwithsingleormultiplealarminitiatingeventsincludingexternalfloodingofsafetyrelatedstructures.Theassociatedactionsforprovidingfloodprotectionandmitigationaredetailedintheprocedure.AdverseWeatherConditionsthatwereAssumedConcurrentwithFloodProtectionFeaturesandAssociatedActions.Adverseweatherconditionsassumedconcurrentwiththeassociatedactionsforprovidingfloodprotectionandmitigationinclude,butarenotlimitedto,highwindsandheavyrainwithstandingwater.NoneoftheseadverseweatherconditionswillimpedetheexecutionoftheSanOnofreAbnormalOperatingInstruction,SevereWeatherortheSanOnofreAlarmResponseInstruction. Section C: Warning Systems to Detect the Presence of Water Requested Information Describeanywarningsystemstodetectthepresenceofwaterinroomsimportanttosafety. SONGS Response WaterLevelWarningSystemsCredited.TheSONGSUnit2andUnit3areequippedwith92mechanicallyactuatedfloodsensorslocatedthroughoutsafety relatedareas,whichprovidethefirstindicationofwaterintrusionfrominternalandexternalsources.Floodsensoralarmsareindicatedoncontrolroomstatuspanels2(3)ZL9480 1and9481 2.ASONGSAlarmResponseInstructionprovidesoperatingpersonnelwithavailableoptionsorpossibilitiesfordealingwithsingleormultiplealarminitiatingevents,includingexternalfloodingofsafety relatedstructures.ScopeofWaterLevelWarningSystemsEvaluation.AsaresultofaTitle10CFR50.56MaintenanceRuleevaluationandresultingcorrectiveactionforfloodsensors(externaltothefloodfeaturewalkdownprogram),aprogramwasinitiatedtoreplaceall92floodsensorswithina2 yearperiodthatstartedinMarch2011.Asaresult SONGS FLOOD WALKDOWN REPORT 8 ofthisreplacementprogram,credithasbeentakenforfloodsensorsthathavebeenreplacedorarescheduledforreplacementinlieuofavisualinspectionaspartofthefloodfeaturewalkdown.Seventyninefloodsensorswerereplacedpriortotheinitiationofthewalkdownsandtheremaining13floodsensorsarescheduledforreplacementpriortotheendofthe2012calendaryear.Eachfloodsensormaintenanceplanwasreviewedtoensurethefloodsensors(1)havebeenorarescheduledtobereplaced,(2)werelastmonitoredortestedwithinperiodicity,and(3)werescheduledforcontinuedmonitoringandtestingwithinperiodicityafterreplacement,andtoensurethat(4)thescopeofthesurveillancewasadequatetoverifytheabilityofthefeaturetomeetitsCLBflood protectionrequirement. Section D: Effectiveness of Flood-Protection Features Requested Information Discusstheeffectivenessofflood protectionsystemsandexterior,incorporated,andtemporaryfloodbarriers.DiscusshowthesesystemsandbarrierswereevaluatedusingtheacceptancecriteriadevelopedaspartofRequestedInformationItem1.h. SONGS Response PurposeoftheWalkdowns.ThepurposeofthefloodfeaturewalkdownwastoverifytheconformanceofexternalfloodfeatureswiththeCLB.Inadditiontothevisualcomponentofthefloodfeaturewalkdown,areviewofthepreventativemaintenanceandsurveillanceprogramswasperformed.ThepurposeofthereviewwastovalidatethatthecreditedfeatureswerecontainedinaprogramthatwouldensuretheircontinuedconformancewiththeCLB.DevelopmentoftheWalkdownFeatureList.TheCLBwasusedtodeterminewhatfloodfeatureswereincludedinthefloodfeaturewalkdownprogram.Sections2and3oftheSanOnofre2&3UFSARprovidedthebasisforfeaturestobeincluded.Basedonthe16typesofflood protectionfeaturesdiscussedinSectionBofthisreport,thelistwaspopulatedwithatotalof729features(727physicalfeaturesand2procedures).AcceptanceCriteriaDevelopment.SONGSadoptedageneralacceptancecriterionfromtheguidanceprovidedbyNEI12 07Section6andAppendixA[1]foreachtypeoffloodfeaturelistedinSectionB.ThisapproachisconsistentwiththeRequestedInformationItem1.hfromEnclosure4ofthe50.54(f)letter[3].TheacceptancecriteriaforeachfloodfeaturewereannotatedinPartB1ofthewalkdownrecordform,includinganyacceptancecriteriafromtheCLBspecifictoagivenflood protectionfeature.EvaluationoftheOverallEffectivenessofthePlant'sFloodProtectionFeatures.Procedures.Asiteprocedure,FukushimaEventResponse-FloodProtectionWalkdownScopingandEvaluation,wascreatedtoprovideguidanceforthescopingandevaluationprocess.Itincludesthefloodfeaturewalkdownprocesstoensureauniformevaluationoftheflood protectionfeaturesagainsttheCLB.ThisprocedurewasdevelopedbasedontheguidanceprovidedinNEI12 07[1].Accessibility.Thefloodfeaturesthatcouldbeaccessedwereevaluatedagainstthedefinedacceptancecriteriadocumentedonthefloodfeaturewalkdownrecordform.Thosefeaturesthatwererestrictedorinaccessiblewereenteredintothecorrectiveactionprogram(CAP).FloodfeaturesclassifiedasinaccessiblearediscussedinSectionFofthisreport.Floodfeatureswithpartialaccessibilitywereevaluatedagainsttheacceptancecriteria,asapplicable,todetermineifimmediateresponsewaswarrantedpriortotheCAPrescheduleddate.Effectiveness.Atotalof729flood protectionfeatures(727physicalfeaturesand2procedures)wereidentifiedandevaluatedattheSONGSsiteanddocumentedonthefloodfeaturewalkdownrecordforms.Theresultsofthefloodfeaturewalkdownprogramshowthattheflood protectionfeaturesare,withtheexceptionoftwoidentifieddeficiencies,effectiveinmeetingtheirintendedcreditedfunctionsbasedupon SONGS FLOOD WALKDOWN REPORT 9 thedefinedacceptancecriteria.Inthosecaseswhereobservationssuggestedthatacceptancecriteriawerenotmetorwerequestionable,thepotentialissuewascapturedintheSONGSCAPtodetermineifitisadeficiencyandwhatactionsaretobetaken.SectionFofthisreportprovidesadetaileddiscussionoftheresultsfromthefloodfeaturewalkdownprogram.OtherExistingPlantEquipment,Structures,andProceduresthatMightMitigatetheEffectsofanExternalFloodunderaVarietyofPlantConfigurations.Catchbasinsforthesubsurfacedrainagesystem,roofdrains,andexposedfloordrainsareassumedpluggedforthepurposeofdeterminingwatersurfaceelevationsarisingduringthethunderstormPMPevent.Sumppumpsandfloordrainsinternaltosafety relatedbuildingsarenotcreditedtoremovewaterduringafloodingevent.Thesefeatureswerenotincludedinthescopeofthefloodwalkdowneffort,butmightbeavailabletomitigatetheeffectsofanexternalfloodevent.AssessmentofMaintenanceandMonitoringProgramsforFloodProtectionFeatures.Areviewofperiodicmaintenance(PM),surveillance,periodicmonitoring,andfunctionaltestingrequirementsforeachoftheflood protectionfeatureswasperformed.ResultsweredocumentedontheNEI12 07walkdownrecordforms(PartB.2).ThePM,surveillance,periodicmonitoring,and/orfunctionaltestingwasconsideredacceptableifitwas(1)withinthescopeofaprogramorprocedure,(2)waslastmaintained,monitored,ortestedwithinperiodicity,and(3)wasscheduledforfuturemaintenance,monitoring,and/ortestingwithinperiodicity;and(4)ifthescopeofthePM,surveillance,ortestwasadequatetoverifytheabilityofthefeaturetomeetitsCLBflood protectionrequirement.AssessmentofMaintenanceActivitiesthatExposeSSCstoFloodHazards.Plantprogramsevaluatetheimpactofplantactivities,includingmaintenanceactivities,ontheabilityofidentifiedflood protectionfeaturestoperformtheircreditedfunction.Compensatorymeasuresrequiredbysiteprogramsareimplemented,whenrequired,toensurethattheflood protectionfunctionismaintained. Section E: Implementation of the Walkdown Process Requested Information Presentinformationrelatedtotheimplementationofthewalkdownprocess(e.g.,detailsofselectionofthewalkdownteamandprocedures)usingthedocumentationtemplatediscussedinRequestedInformationItem1.j,includingactionstakeninresponsetothepeerreview. SONGS Response WalkdownGuidanceandExceptions.Procedures.ToensureNEI12 07guidancewasfollowed,asite specificprocedure,FukushimaEventResponse-FloodProtectionWalkdownInspectionProcess,forguidingtheinspectionprocesswascreatedtoensurecompliancewiththefloodfeaturewalkdownexecutionanddocumentationbasedonthecriteriaoutlinedinNEI12 07Sections5.3,7,andAppendixB[1].WalkdownPackages,Pre JobBrief,andPost JobBrief.ThefloodfeaturewalkdownpackagesweredevelopedbaseduponthespecificguidanceprovidedinNEI12 07Section5.2,PrepareWalkdownPackages[1],whichincludedthefollowingcomponents:Pre JobBrief,WalkdownGuidanceandAcceptanceCriteria,WalkdownRecordForm,DesignDrawings,GeneralArrangementDrawings,andFloodProtectionStrategyImplementationProcedures.Eachpre jobbriefcontainedthefollowing:IndustrialSafety,RadiologicalSafety,DoseRequirements,AcceptanceCriteria,PlantStatus,IndustryOperatingExperience,ProcedureCompliance,ReportingDegradedConditions,PositiveComponentVerification,InspectionMethodology,andFieldDocumentationRequirements.

SONGS FLOOD WALKDOWN REPORT 10 Atthecompletionofeachdayduringthepost jobbrief,thewalkdownteamwoulddiscusslessonslearnedforthatdayandtheinspectionplanforthenextday'sfloodfeatures.Exceptions.NoexceptionsweretakentotheendorsedguidanceofNEI12 07[1].TeamOrganization.TheSONGSfloodprotectionwalkdownteamwascomposedofqualifiedindividualsofvarioustechnicaldisciplines,asshowninExhibitE 1:SONGSFloodFeatureWalkdownTeamComposition.AssuggestedbyNEI12 07Section5.3[1],multipleskillsetswereavailabletoparticipateintheevaluationofagivenfloodmitigationfeaturedependingontheintendedcreditedfunction.Eachfloodmitigationfeaturewasevaluatedbyaminimumoftwoindividualsfromtheteam.EXHIBITE 1SONGSFloodFeatureWalkdownTeamCompositionWalkdownExecutionTeamYearsofExperienceSONGSOversightYearsofExperienceSeniorNuclearConsultant40ProjectManager(SeniorElectricalEngineer)30NuclearConsultant13TaskTechnicalLead(SeniorCivilEngineer)15LicensingandHydrogeologistConsultant15CivilEngineer25NuclearConsultant6ConsultingSeniorMechanicalEngineer36CivilEngineer10CompliancewithSection5.3ofNEI12 07.Thefloodfeaturewalkdownteammembersrepresentedfivedisciplineareas,asshowninExhibitE 1.Theexecutionteamswerepairedtoensurethatcomplementaryskillsetswereactivelyengagedineachfeatureevaluation(e.g.,pairinglicensingexpertisewithfield/inspectionexperience).ThefloodfeaturewalkdownteamwasmadefamiliarwiththeinformationrequiredtorespondtoSECY11 0137Items2.1(FloodHazardEvaluation)and2.3(FloodWalkdown)[2],aswellas50.54(f)letterEnclosures2and4[3].Thefloodfeaturewalkdownteammembers(excludingcraftsupport,healthphysicspersonnel,etc.)werealsocurrentinNEI developedtrainingprovidedthroughtheNANTeLwebsite(https://nantel.org).InadditiontotheNANTeLtraining,site specifictrainingwasdevelopedanddeliveredtofurtherenhancetheteam'sunderstandingoftheimportanceofthefloodfeaturewalkdownprogram.AlltrainingrecordsforfloodfeaturewalkdownteamparticipantsaredocumentedintheSONGStrainingrecordsdatabase.Thesiteproceduredevelopedtogoverntheinspectionprocessincludedaqualificationsmatrix,whichcomplieswithSection5.3andAppendixCofNEI12 07[1]. Section F: Results of the Flood Feature Walkdown Requested Information Resultsofthewalkdownincludingkeyfindingsandidentifieddegraded,non conforming,orunanalyzedconditions.IncludeadetaileddescriptionoftheactionstakenorplannedtoaddresstheseconditionsusingtheguidanceinRegulatoryIssuesSummary2005 20,Rev1,RevisiontoNRCInspectionManualPart9900TechnicalGuidance,"OperabilityConditionsAdversetoQualityorSafety,"includingenteringtheconditioninthecorrectiveactionprogram.

SONGS FLOOD WALKDOWN REPORT 11 SONGS Response SummaryofFindings.Theplantflood protectionfeatureswerefoundtobeasdescribedintheCLB(available,functional,andmaintained),withjustafewexceptionsthatareconsidereddeficiencies.Thesedeficienciesaredescribedinthe"Deficiencies"sectionbelow.Thedeficienciesnotwithstanding,theflood protectionfeaturesinaggregatewouldperformtheirdesignfunctionascreditedintheCLB.Detailedobservations,photographs,andqualitativedispositionswereenteredintotheSONGSRecommendation2.3FloodFeaturesDatabaseforeachfeatureandhavebeentransmittedtocentraldocumentmanagement(CDM).Twenty fivefloodfeatureswereaddedtotheCAPformaterialordesignevaluationandwereannotatedinthewalkdownrecordforms.Ofthe25itemsaddedtotheCAP,7wereevaluatedfordeficiencydeterminationand2deficienciesweredeterminedpertheCAP(see"Deficiencies"sectionbelowforfurtherdiscussiononthefeaturesidentifiedasdeficiencies).GenericissuesidentifiedduringthewalkdownsandenteredintotheCAP,butnotconsidereddeficiencies,includethefollowing: Penetrationsealsandfloodfeatureswithincorrectormissingidentificationtags MaterialconditionissuesthatdonotchallengetheabilityofthefeaturetomeettheCLBflood protectionrequirement FeaturesnotlistedintheSanOnofre2&3UFSAR Errorsindrawingsordocuments Operationsprocedurecorrectionsandenhancements(asdiscussedbelow) Floodfeatureproceduralmonitoringenhancements(asdiscussedbelow)Ofthe727physicalfloodfeatures,21weredeterminedtohaverestrictedaccessandwereenteredintotheCAPforfutureschedulinganddisposition.Additionally,10floodfeaturesweredeterminedtobeinaccessibleduetoeitherametallicbelloworsteelplatestructureobstructingthefeature.SONGSengineeringpersonnelperformedanevaluationofeachinaccessiblefeatureanddeterminedthefeaturesarecapableofperformingtheircreditedCLBfunction(see"FeaturesthatareInaccessible"sectionbelowforfurtherdiscussion).Ofthe727physicalfloodfeatures,allwereincludedinapreventativemaintenanceorsurveillanceprogramwiththeexceptionof39features.These39featureswereenteredintotheCAPfordeterminationoftheneedtobeincludedinapreventativemaintenanceorsurveillanceprogram.ThelackofinclusionwasdeterminedbytheCAPnottobeadeficiencyofthepreventativemaintenanceorsurveillanceprograms.Floodsensorscreditedfordetectingexternalandinternalfloodingwerereviewedthoughtherespectivemaintenanceplansandthereplacementprogram.Thereviewconsistedof(1)evaluatingtoensurethefloodsensorhasbeenreplacedorisscheduledforreplacementperplantschedule,and(2)thefloodsensorisscheduledformaintenanceandtestingontherequiredperiodicityafterthereplacementdate.Noadversefindingsweredetermined.AdditionalinformationconcerningfloodsensorsisprovidedaboveinSectionC:WarningSystemstoDetectthePresenceofWater.TwositeproceduresarecreditedforresponsetoexternalfloodresponseandwereevaluatedusingareasonablesimulationasdescribedintheNEI12 07guidance[1].Thereasonablesimulationconsistedofasimulatedseverestormreachingthecriteriaofentryrequiringoperatoractiontovalidatetheplantconfiguration.Subsequently,asimulatedsignificantrainfallwasinitiatedresultinginfloodsensoralarmresponsefromsimulatedwateringressperthealarmresponseprocedure.Thisresultedinoperatorresponseinthreelocations,twoinSONGSUnit3andoneinSONGSUnit2.Asaresultoftheproceduresimulation,twonon safety relateditemswithintheprocedureswereidentifiedasneedingtobeaddressedandseveralenhancementsweresuggestedtolessenoperatorburdeninidentifyingthereferencedfeatures.TheseitemswereenteredintotheCAP.NoneoftheidentifieditemsorsuggestionswasdeterminedbytheCAPtobeadeficiencytotheprocedures.Theresultsofthereasonable SONGS FLOOD WALKDOWN REPORT 12 simulationgoverningsitepreparationandresponseforthelicensingbasisfloodeventwereadequateandcouldbecompletedwithinthewarningtime,asspecifiedintheprocedures.Additionally,trainingfortheprocedureswasdeterminedtobeadequate.Thecriteriafortrainingadequacyweredeterminedby(1)thesuccessfulperformanceoftheseverestormsimulationinwhichtheprocedureswereimplemented,and(2)reviewandvalidationoftrainingrecordsandperiodicity.AlltrainingrecordsareavailableintheSONGStrainingrecordssystem.DescriptionofAnyObservationsReportedintheCAPthatWereNotDispositioned.AllfloodfeaturewalkdownobservationsenteredintotheCAPhavebeenscreenedandassociatedactionshavebeenassigned.Deficiencies.AsdeterminedbytheCAP,twofeaturesweredeterminedtobedeficienciesmeetingthecriteriaofdegraded,nonconforming,orunanalyzed.Thetwodeficienciesarediscussedbelowinthenextsubsection,providingcondition,descriptionoffeature,functionallocation,discussionofthedegradedornonconformingcondition,actionstaken,andanticipatedcompletiondateforrepairs.Althoughthesefeaturesaredefinedasdeficiencies,theyposelimitedrisktoplantoperationsastheyarepassiveexternalpenetrationsthatprotectagainstexternalwateringressanddonotprovidecriticalsafetyfunctionstoensureplantsafetyrelatedequipmentcanperformtheintendedfunctions.DescribeActionsthatWereTakenorArePlannedtoAddresstheDeficiencies.Thefollowingactionsweretakeorareplannedtoaddressthedeficiencies: DegradedUnit3RoofDrainPipe(FunctionalLocationS3.PENS.EGT011.502720303).Severecorrosionandwidecrackswereidentifiedonthecast irondrainpipeservicingtheroofoftheUnit3UndergroundElectricalandPipingGalleriesStructure.ThisconditionrepresentsaleakagepathintotheUnit3UndergroundElectricalGalleriesTunnelduringapostulatedPMPevent.Thedrainattheroofhasbeenpluggedtopreventwaterfromleakingintotheundergroundtunnelthroughthefaileddrainpipe.Anorderhasbeengeneratedtoreplacethedegradeddrainpipe.TheanticipatedcompletiondatefortherepairJuly2013. Non ConformingUnit3UndergroundElectricalCableTunnelDuctBankSeal,Conduit1of4(FunctionalLocationS3.PENS.UCT009.502520143).Waterstaining,corrosion,andmissingfire protectionsealmaterialwereidentifiedforanelectricalconduitthatispartofaductbankpenetratingtheUnit3UndergroundCableTunnel.ThisconditionrepresentsaleakagepathfromanoutsideelectricalmanholeintotheUndergroundCableTunnelthroughtheunsealedconduitduringapostulatedexternalfloodingevent.Thesurfacecoverattheoutsidemanholecoverissealed,significantlyrestrictingtheamountofwaterthatcouldtravelintotheundergroundtunnelthroughtheconduit.Asaresultofthewalkdowneffort,aworkorderwasgeneratedtoinstallthesealintheconduit.Thesealwasinstalled10/24/2012andtheconditionisnolongeradeficiency.FeaturesAffectedbyRestrictedAccess.DuringthecourseoftheSONGSFloodFeatureWalkdownProgram,21featureswereaffectedbyrestrictedaccess.JustificationforDelay.Thebulletedlistbelowprovidesthevariousjustificationsfordelayandrequiredactiontogainaccess. Fireretardantormetallicinsulationobstructingvisualinspection Mitigation:scheduleinspectioninfuturewithmaintenancesupporttoremoveinsulation Featureatanelevationrequiringscaffolderectiontoallowforvisualinspection Mitigation:scheduleinspectioninfuturewithmaintenancesupporttoerectscaffolding Featureobstructedbyinstalledplantsystems,structures,and/orcomponents Mitigation:scheduleinspectioninfuturewithmaintenancesupportfornextscheduledpreventativemaintenanceorsurveillance SONGS FLOOD WALKDOWN REPORT 13 ScheduleforCompletionofInspection.AllrestrictedaccessinspectionswillbecompletedbyJuly2013.SpecialProceduresRequiredforInspection.Nospecialproceduresarerequiredforinspectionoftherestricted accessfeatures.Thefeaturesrequireadditionalplantsupportthatwasnotavailableduetonormalplantoperations.FeaturesthatareInaccessible.Tenfeaturesweredeterminedtobeinaccessibleandaredescribedbelow.1. RubberWaterstopsbetweentheContainmentStructure(RecirculatingRooms)andtheSafetyEquipmentBuilding.EachSONGSUnitContainsOneWaterstopatthisLocation.ReasonInaccessibleThewaterstopsarecoveredbymetalbellowsweldedtothepermanentstructure.Inspectionwouldrequiremajordisassembly.FunctionalRequirementRubberwaterstopspreventorlimitwaterintrusionattheseismicgapsothatsafetyrelatedequipmentisnotimpactedbythefloodlevel.LocationWaterstopsarelocatedintherecirculationrooms(bottomelevation 12'9"mllw)intheseismicgapbetweenstructures.TheroomisaccessedfromtheContainmentTendonGallery.BasisforReasonableAssurancethatFeatureisAvailableandFunctionalPotentialwaterinleakageatwaterstopshasbeenevaluatedinanexistingdesigncalculation.TheSONGScalculationforPlantFloodAnalysisReviewpostulatedtheworst casescenariobypositioningacrackintherubberwaterstopatthelowestelevation, 12'9"mllw.Thepredictedleakagerateduetoanexternalsourceismuchlessthanfloodingduetoaninternalcomponentfailureoractuationofthefire protectionsprinklers.AsafetyrelatedfloodsensorislocatedineachrecirculationroomandalarmsintheControlRoom,withoperatorresponsespecifiedintheAlarmResponseInstruction.Theseflooddetectorshaverecentlybeenreplacedandhaveperiodicfunctionaltesting.Therefore,thefloodeffectsareboundedandthereisnoadverseimpacttosafetyrelatedequipment.AggregateEffectsThereisnocommonfailuremechanismfortherubberwaterstopsduringthecurrentlicensingbasisfloodevent(PMP).Floodsensorsarelocatedineachrecirculationroom,sooperatorresponsewouldlimitfloodeffectsandpreventimpactstosafetyrelatedequipmentfromgroundwateringress.2. WaterstopsbetweentheAuxiliaryControlBuilding(ChilledWaterTunnel)andtheSafetyEquipmentBuilding.SharedWaterstopatNorthandSouthEndoftheTunnel.ReasonInaccessibleThewaterstopsarecoveredbymetalbellowsweldedtothepermanentstructure.Inspectionwouldrequiremajordisassembly.FunctionalRequirementRubberwaterstopspreventorlimitwaterintrusionattheseismicgapsothatsafetyrelatedequipmentisnotimpactedbythefloodlevel.LocationWaterstopsarelocatedintheChilledWaterPipingtunnel(bottomelevation5'11"mllw)intheseismicgapbetweentheSafetyEquipmentBuildingandtheAuxiliary ControlBuilding.BasisforReasonableAssurancethatFeatureisAvailableandFunctional SONGS FLOOD WALKDOWN REPORT 14 Potentialwaterinleakageatwaterstopshasbeenevaluatedinanexistingdesigncalculation.TheSONGScalculationforPlantFloodAnalysisReviewpostulatedtheworst casescenariobypositioningacrackintherubberwaterstopatthelowestlevelelevation, 12'9"mllw.Thepredictedleakagerateduetoanexternalsourceismuchlessthanfloodingduetoaninternalcomponentfailureoractuationofthefire protectionsprinklers.AsafetyrelatedfloodsensorislocatedineachchilledwaterpipingtunnelandalarmsintheControlRoom,withoperatorresponsespecifiedintheAlarmResponseInstruction.Theseflooddetectorshaverecentlybeenreplacedandhaveperiodicfunctionaltesting.Therefore,thefloodeffectsareboundedandthereisnoadverseimpacttosafetyrelatedequipment.AggregateEffectsThereisnocommonfailuremechanismfortherubberwaterstopsduringthecurrentlicensingbasisfloodevent(PMP).Floodsensorsarelocatedineachchilledwatertunnel,sooperatorresponsewouldlimitfloodeffectsandpreventimpactstosafetyrelatedequipmentfromgroundwateringress.3. WaterstopsbetweentheAuxiliaryPenetrationAreaandtheSafetyEquipmentBuilding(ShutdownHeatExchangerPipingTunnel).EachSONGSUnitContainsOneWaterstopatthisLocation.ReasonInaccessibleThewaterstopsarecoveredbymetalbellowsweldedtothepermanentstructure.Inspectionwouldrequiremajordisassembly.FunctionalRequirementRubberwaterstopspreventorlimitwaterintrusionattheseismicgapsothatsafetyrelatedequipmentisnotimpactedbythefloodlevel.LocationWaterstopsarelocatedintheShutdownHeatExchangerPipingTunnel(elevation8'6"mllw)intheseismicgapbetweentheAuxiliary PenetrationstructureandSafetyEquipmentBuilding.BasisforReasonableAssurancethatFeatureisAvailableandFunctionalPotentialwaterinleakageatwaterstopshasbeenevaluatedinanexistingdesigncalculation.TheSONGScalculationforPlantFloodAnalysisReviewpostulatedtheworst casescenariobypositioningacrackintherubberwaterstopatthelowestlevelelevation, 12'9"mllw.Thepredictedleakagerateduetoanexternalsourceismuchlessthanfloodingduetoaninternalcomponentfailureoractuationofthefire protectionsprinklers.AsafetyrelatedfloodsensorislocatedineachtunnelandalarmsintheControlRoom,withoperatorresponsespecifiedintheAlarmResponseInstruction.Theseflooddetectorshaverecentlybeenreplacedandhaveperiodicfunctionaltesting.Therefore,thefloodeffectsareboundedandthereisnoadverseimpacttosafetyrelatedequipment.AggregateEffectsThereisnocommonfailuremechanismfortherubberwaterstopsduringthecurrentlicensingbasisfloodevent(PMP).Floodsensorsarelocatedineachshutdownheatexchangerpipingtunnel,sooperatorresponsewouldlimitfloodeffectsandpreventimpactstosafetyrelatedequipment.4. WaterstopsbetweentheAuxiliaryPenetrationAreaandtheSafetyEquipmentBuilding(Corridor027).EachSONGSUnitContainsOneWaterstopatthisLocation.ReasonInaccessibleThewaterstopsarecoveredbysteelplatesfastenedtothepermanentstructure.Inspectionwouldrequiremajordisassembly.FunctionalRequirement SONGS FLOOD WALKDOWN REPORT 15 Rubberwaterstopspreventorlimitwaterintrusionattheseismicgapsothatsafetyrelatedequipmentisnotimpactedbythefloodlevel.LocationWaterstopsarelocatedintheseismicgapbetweentheAuxiliaryPenetrationAreaandtheSafetyEquipmentBuilding(bottomoftheopeningiselevation8'0"mllw).BasisforReasonableAssurancethatFeatureisAvailableandFunctionalThebottomofthewaterstopislocatedabovethesitegroundwaterlevel.Potentialwaterin leakageatwaterstopshasbeenevaluatedinanexistingdesigncalculation.TheSONGScalculationforPlantFloodAnalysisReviewpostulatedtheworst casescenariobypositioningacrackintherubberwaterstopatthelowestlevelelevation,12'9"mllw.Thepredictedleakagerateduetoanexternalsourceismuchlessthanfloodingduetoaninternalcomponentfailureoractuationofthefire protectionsprinklers.In leakageatthewaterstopatthislocationwouldbecontainedinthecorridorduetoasteelfloodbarrieratthewestendofthecorridorandwatertightdoorsattheotheropenings.Thereisnoadverseimpacttosafety relatedequipment.AggregateEffectsWaterin leakageiscontainedinthecorridorandthereisnoimpacttosafety relatedequipment.5. WaterstopsforthePipingOpeningbetweentheAuxiliaryPenetrationAreaandtheSafetyEquipmentBuilding(FLOCsS2.PENS.SE00802620012andS3.PENS.00802620033).EachSONGSUnitContainsOneWaterstopatthisLocation.ReasonInaccessibleThewaterstopsarecoveredbysteelplatesfastenedtothepermanentstructure.Inspectionwouldrequiremajordisassembly.FunctionalRequirementRubberwaterstopspreventorlimitwaterintrusionattheseismicgapsothatsafetyrelatedequipmentisnotimpactedbythefloodlevel.LocationWaterstopsarelocatedintheseismicgapbetweentheAuxiliaryPenetrationAreaandtheSafetyEquipmentBuilding(bottomofopeningiselevation19'6"mllw).BasisforReasonableAssurancethatFeatureisAvailableandFunctionalThebottomofthewaterstopislocatedabovethesitegroundwaterlevel.Potentialwaterin leakageatwaterstopshasbeenevaluatedinanexistingdesigncalculation.TheSONGScalculationforPlantFloodAnalysisReviewpostulatedtheworst casescenariobypositioningacrackintherubberwaterstopatthelowestlevelelevation,12'9"mllw.Thepredictedleakagerateduetoanexternalsourceismuchlessthanfloodingduetoaninternalcomponentfailureoractuationofthefire protectionsprinklers.In leakageatthewaterstopwouldflowthroughflooraccessopeningstoelevation5'6"mllwandbecontainedintheComponentCoolingWaterPipingArea.ThereisasafetyrelatedfloodsensorinthisareathatalarmsintheControlRoom,withoperatorresponsespecifiedintheAlarmResponseInstruction.Theseflooddetectorshaverecentlybeenreplacedandhaveperiodicfunctionaltesting.Therefore,thefloodeffectsareboundedandthereisnoadverseimpacttosafetyrelatedequipment.AggregateEffectsThereisnocommonfailuremechanismfortherubberwaterstopsduringthecurrentlicensingbasisfloodevent(PMP).Waterin leakagewouldcollectinanareawithfloodsensors;operatorresponsewouldlimitfloodeffectsandpreventimpacttosafety relatedequipment.

SONGS FLOOD WALKDOWN REPORT 16 WalkdownRecordForms.Thewalkdownrecordformshavebeencompletedanddetailedobservations,photographs,andqualitativedispositionswereenteredintotheSONGSRecommendation2.3FloodFeaturesDatabaseforeachfeatureandhavebeentransmittedtoCDM. Section G: Cliff-Edge Effects Requested Information Documentanycliffedgeeffectsidentifiedandtheassociatedbasis.Indicatethosethatwereenteredintothecorrectiveactionprogram.Alsoincludeadetaileddescriptionoftheactionstakenorplannedtoaddresstheseeffects. SONGS Response CliffEdgeEffectsandPhysicalMargins.AsindicatedinSection3.12ofNEI12 07[1],theNRCisnolongerexpectingtheRecommendation2.3:FloodingWalkdownsofthe50.54(f)letter[3]toincludeanevaluationofcliff edgeeffects.Theavailablephysicalmargin(APM)hasbeenestimatedanddocumented,asapplicable,inthewalkdownrecordforms.TheguidanceprovidedinNEIFAQ 006wasalsofollowed.ThisinformationwillbeusedinthefloodhazardreevaluationsperformedinresponsetoItem2.1:Floodinginthe50.54(f)letter[3]. Section H: Other Planned and/or Newly Installed Flood-Prote ction Features or Measures Requested Information Describeanyotherplannedornewlyinstalledflood protectionsystemsorfloodmitigationmeasuresincludingfloodbarriersthatfurtherenhancethefloodprotection.Identifyresultsandanysubsequentactionstakeninresponsetothepeerreview. SONGS Response ChangesDeterminedtobeNecessary.Flood protectionfeatureswithlowAPMhavebeenenteredintotheCAPforfurtherevaluationandconsiderationtoincreasemargin. Conclusion The727identifiedplantflood protectionphysicalfeatures,themajorityofwhichwereincorporatedpassiveprotectionfeatures,werefoundtobeasdescribedintheCLB(available,functional,andmaintained)withafewexceptionsasdescribedinSectionF:Deficiencies.Thedeficienciesnotwithstanding,theflood protectionfeaturesinaggregatewouldperformtheirdesignfunctionascreditedintheCLB.Asummaryofthefindingsisbelow.Additionalflood protectionfeatureswereidentifiedduringthefloodwalkdownthatprotectagainstexternalingressofwaterintoSSCsimportanttosafetybutnotincludedintheSanOnofre2&3UFSAR[4].Thesefeatureswereevaluatedaccordingtoacceptancecriteriadevelopedforsimilarflood protectionfeaturesandwerefoundtomeettheacceptancecriteria.TheseitemswereaddedtotheCAPandwillbeevaluatedfortheirneedtobeincludedintheSanOnofre2&3UFSAR.Deficiencies Twoobservationsweredeterminedtobedeficiencies(seeSectionF:Deficiencies).ThetwodeficiencieswereenteredintotheCAP.Oneofthedeficiencieswassubsequentlycorrected,andthecorrectiveactionfortheotherdeficiencyisanticipatedtobecompletebyJuly2013.Thesedeficienciesarepassiveexternalpenetrationsthatprotectagainstexternalwateringressandarenotrequiredforplantsafetyrelatedequipmenttofunction.

SONGS FLOOD WALKDOWN REPORT 17 Restricted-Access Flood Features Twenty onefloodfeaturesweredeemedrestricted accessandrequirefutureschedulinganddisposition.RestrictedaccessfeatureshavebeenenteredintotheCAPandaddedtotheworkweekprocesstoalignplantsupport.Allrestricted accessfeatureswillbetrackedbytheirrespectivemaintenanceordersandarecurrentlyscheduledforvisualinspectionbyJuly2013.Inaccessible Flood Features TenfloodfeaturesweredeemedinaccessibleandenteredintotheCAPforengineeringevaluation.ThesefeatureswereevaluatedbySONGSengineeringpersonnelanddeterminedtohavereasonableassurancethattheywillperformtomeettheirintendedCLBfunction.TheSONGScalculationforPlantFloodAnalysisReviewpostulatedtheworst casescenariobypositioningacrackintherubberwaterstopatthelowestlevelelevation, 12'9"mllw.Thepredictedleakagerateduetoanexternalsourceismuchlessthanfloodingduetoaninternalcomponentfailureoractuationofthefire protectionsprinklers. References 1.NuclearEnergyInstitute(NEI).2012.GuidelinesforPerformingVerificationWalkdownsofPlantFloodProtectionFeatures.NEI12 07Rev.0.May2012.2.U.S.NuclearRegulatoryCommission(NRC).2011.PrioritizationofRecommendedActionsToBeTakenInResponsetoFukushimaLessonsLearned.SECY 110137,October3,2011.3.U.S.NuclearRegulatoryCommission(NRC).2012.RequestforInformationPursuanttoTitle10oftheCodeofFederalRegulations50.54(f)RegardingRecommendations2.1,2.3,and9.3oftheNearTermTaskForceReviewofInsightsfromtheFukushimaDaiichiAccident(50.54(f)letter).March12,2012.4.SanOnofreNuclearGeneratingStation.2009.SanOnofreUnit2&3UpdatedFinalSafetyAnalysisReport(UFSAR).April2009.5.U.S.WeatherBureau.1961.HydrometeorologicalReportNumber36(HMR36).6.Wilson,Dr.B.W.1972.EstimateofTsunamiEffectatSanOnofreNuclearGeneratingStation,Units2and3.December1972.7.NuclearEnergyInstitute(NEI).1996.GuidelineforMonitoringtheEffectivenessofMaintenanceatNuclearPowerPlants.NUMARC93 01Rev.2.April1996.