ML081420793

North Anna, Units 1 and 2, and Surry, Units 1 & 2, NRC Generic Letter (GL) 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors Request..

ML081420793
Person / Time
Site:	Millstone, Kewaunee, Surry, North Anna
Issue date:	05/21/2008
From:	Bischof G T Dominion, Dominion Energy Kewaunee, Dominion Nuclear Connecticut, Dominion Resources Services, Virginia Electric & Power Co (VEPCO)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
08-0275, GL-04-002
Download: ML081420793 (57)

Text

Dominion Resources Services, Inc.

Dominion Boulevard, GlenAllen,VA.')1 if,(!\V,*hAddress:

www.dom.com May 21, 2008U.S.NuclearRegulatoryCommissionAttention:DocumentControlDeskOneWhiteFlintNorth11555RockvillePikeRockville,MD20852-2738SerialNo.NL&OS/GDMDocketNos.LicenseNos.

08-0275 R4 50-305 50-336/423 50-338/339 50-280/281 DPR-43 DPR-65/NPF-49 NPF-4/7 DPR-32/37 DOMINION ENERGY KEWAUNEE, INC.DOMINION NUCLEAR CONNECTICUT, INC.VIRGINIA ELECTRICANDPOWER COMPANY KEWAUNEE POWER STATION MILLSTONE POWER STATIONUNITS2AND3 NORTHANNAANDSURRYPOWERSTATIONUNITS1AND2 NRC GENERIC LETTER(GL)2004-02,POTENTIALIMPACTOFDEBRIS BLOCKAGE ON EMERGENCY RECIRCULATIONDURINGDESIGNBASIS ACCIDENTS AT PRESSURIZED-WATER REACTORS REQUESTFOREXTENSIONOF COMPLETIONDATESFOR CORRECTIVE ACTIONSInaletterdatedSeptember1,2005(SerialNo.05-212),DominionEnergyKewaunee,Inc.(DEK),DominionNuclearConnecticut,Inc.(DNC)andVirginiaElectricandPowerCompany(Dominion)submittedaresponsetoNRCGenericLetter2004-02,"PotentialImpactofDebrisBlockageonEmergencyRecirculationduringDesignBasisAccidents at Pressurized-WaterReactors."Inthatletter,DominioncommittedtocompletingcorrectiveactionsrequiredbyGL2004-02toresolveNRCGenericSafetyIssue(GSI)191,"AssessmentofDebrisAccumulationonPWRSumpPerformance,"byDecember31,2007forKewauneePowerStation(Kewaunee),MillstonePowerStationUnits2and3(MillstoneUnits2and3),NorthAnnaPowerStationUnits1and2(NorthAnnaUnits1and2),andSurryPowerStationUnits1and2(SurryUnits1and2).Ina subsequentletterdatedJanuary11,2007(SerialNo.06-481),DominionsubmittedanextensionrequestforSurryUnit2topermitthecompletionoftheinstallationoftherecirculationspraypumpstrainersystemduringthespring2008refuelingoutage(RFO).TheNRCapprovedtheSurryUnit2extensionrequestintheirletterdatedMarch8,2007.

Serial Number 08-0275DocketNos.

50-305/336/423/338/339/280/281GL2004-02;Requestfor ExtensionsPage2of6InasubsequentletterdatedNovember15,2007(SerialNo.07-0660),DEK,DNCandDominionsubmittedextensionrequestsforKewaunee,MillstoneUnits2and3,NorthAnnaUnits1and2andSurryUnits1and2primarilyforthecompletionofdownstreameffectsevaluationsandchemicaleffectstestingandevaluation.Justificationwasprovidedfortheindividualplantextensionsinaccordancewiththe"CriteriaforEvaluatingDelayofHardwareChanges,"asdescribedinSECY-06-0078datedMarch31,2006.TherequestedextensiondateswereJune30,2008forKewauneeandNovember30,2008forMillstone,NorthAnnaandSurry.DuetotheimportanceofpromptclosureofGL2004-02,theNRCgrantedDominionanextensiontoMay31,2008foreachplanttocompletetheoutstandingcorrectiveactionsidentifiedintheextensionrequests.However,thestaffalsostatedthatshouldDominionbeunabletocompletetheGL2004-02correctiveactionsbyMay31,2008,additionaljustificationmustbeprovidedtotheNRCforanyrequestedextensionbeyondMay 31,2008.Considerableeffortandresourceshavebeenexpendedtocompletetheoutstandingcorrectiveactionsforeachstationbytheapprovedextensiondate,andsignificantprogresshasbeenmadetowards thoresolutionoftheremaining GSI-191issues.DNCandDominionhavehadextensiveinteractionwiththeNRCoverthepastseveralmonthsregardingthetestingprotocolsusedforthechemicaleffectstestingfortheMillstone,NorthAnnaandSurryunits,includingNRCobservationofreducedscaletestingactivitiesatthevendor testing,facility.However,ithasbecomeevidentthatalloftheremainingcorrectiveactionscannotbecompletedbyMay31,2008.Theremainingcorrectiveactionsareidentifiedinthefollowingtable:

Plant Kewaunee Remaining Corrective Actions thatRequirean Extension*Completepost-LOCAcontainmentsumppoolcomputationalfluiddynamics(CFD)analysis*CompletestrainerperformancetestinganddocumentationupdatethatconfirmsKewaunee'slowfiberquantityandcontainmentsumppooltransportcharacteristicsdonotresultinathinorthickbedofdebrisonthesumpstrainer*FollowingcompletionoftheCFDanalysisandstrainerperformancetestinganddocumentation,updatetheKewauneeUpdatedSafetyAnalysisReport(USAR)

PlantMillstoneUnits2and3NorthAnnaUnits1and2SurryUnits1and2 Serial Number 08-0275DocketNos.

50-305/336/423/338/339/280/281GL2004-02; Request for Extensions Page 3 of6 Remaining CorrectiveActionsthatRequireanExtension

• Issuance and internal review of chemical evaluation and benchtop testing reports*CompletionofEmergencyCoreCoolingSystem(ECCS)downstreamcomponentwear,systemperformance,andpumpsealevaluations*Completionofchemicaleffectsreducedscaletesting,evaluation,andtestreportpreparationandreview*Determinewhetheranyadditionalactionsarerequired basedontheresultsofthechemicaleffectstestingandevaluations*Updatedesignandlicensingbasisdocuments(e.g.,UFSAR)toreflecttheplantchangesimplementedtoresolveGSI-191issues*Completeinternalreviewandissueoffinalanalysesandevaluationreportsofbench-toptesting,downstreamcomponentwearandsystemperformance,anddebrisgenerationand transport*Completechemicaleffectsreducedscaletesting,evaluation,andtestreportpreparationandreview*Determinewhetheranyadditionalactionsarerequired basedontheresultsofthechemicaleffectstestingandevaluations*Updatedesignandlicensingbasisdocuments(e.q.,UFSAR)toreflectplantchangesimplementedtoresolveGSI-191issues Attachments1through4providethebasesfortheproposedextensionsoftheGL2004-02correctiveactioncompletiondatesforKewaunee,MillstoneUnits2and3,NorthAnnaUnits1and2,andSurryUnits1and2,respectively.Theextensionbasisforeachplantprovidesadequateassurancethatsafe,continuedoperationwillbemaintainedduringtherequestedextensionperiod.Kewaunee,MillstoneUnits2and3, Serial Number 08-0275 Docket Nos.50-305/336/423/338/339/280/281GL2004-02; Request for ExtensionsPage4 of6NorthAnnaUnits1and2,andSurryUnits1and2currentlymeet,andwill continue to meet theircurrentplantlicensingbasesregardingthefunctionand operabilityofthe containmentsumpduringtheperiod oftherequestedextensions.Asaresultoftheremainingrequiredactivitiesnotedaboveanddiscussedinthe attachments,anextensionto September30,2008isrequestedforKewaunee,MillstoneUnits2and3,NorthAnnaUnits1and2,andSurryUnits1and2tocompletetheGL2004-02correctiveactions.Ifyouhaveanyquestionsorrequireadditionalinformation,pleasecontactMr.GaryD.Millerat(804)273-2771.

Sincerely, Gerald T.BischofVicePresident-Nuclear Enqineerinq COMMONWEALTH OF VIRGINIA))COUNTYOFHENRICO)Theforegoing documentwasaclknowledgedbeforeme,inandfortheCountyand Commonwealthaforesaid,today by Gerald T.Bischof,whoisVice President-NuclearEngineeringofDominionEnergyKewaunee,Inc.,DominionNuclear Connecticut,Inc.andVirginiaElectricandPowerCompany.Hehasaffirmedbeforemethatheisdulyauthorizedtoexecuteandfiletheforegoing document in behalfofthosecompanies,andthatthestatementsinthe documentaretruetothebest ofhisknowledgeandbelief.

Acknowledgedbeforemethis di day of'2008.My Commission EX Pires:..4 4p 51,..1010.VICKIL.HULL Notary PublIc Comrnonweclth Of YIfVlnIG.t.....2 conwnlllion 11.11110NotaryPublic Serial Number 08-0275DocketNos.

50-305/336/423/338/339/280/281GL2004-02;RequestforExtensions Page 5of6 Attachments:1.RequestforanExtensionoftheCompletionDateforCorrectiveActions,KewauneePowerStation2.RequestforanExtensionoftheCompletionDateforCorrectiveActions,MillstonePowerStationUnits2and33.RequestforanExtensionoftheCompletionDateforCorrectiveActions,NorthAnnaPowerStationUnits1and24.RequestforanExtensionoftheCompletionDateforCorrectiveActions,SurryPowerStationUnits1and2 Commitmentsmadeinthiscorrespondence:Thislettercontainsnonewcommitments.Completiondatesarechangedforregulatory commitments previouslyassociatedwithGL2004-02.cc:U.S.NuclearRegulatoryCommissionRegionI475AllendaleRoadKingofPrussia,Pennsylvania19406-1415U.S.NuclearRegulatoryCommissionRegionIISamNunnAtlantaFederalCenter 61ForsythStreet,SWSuite23T85Atlanta,Georgia30303U.S.NuclearRegulatoryCommissionRegionIII 2443 Warrenville RoadSuite210Lisle,Illinois60532-4352 NRC SeniorResidentInspectorKewauneePowerStation NRC SeniorResidentInspectorMillstonePowerStation NRC SeniorResidentInspectorNorthAnnaPowerStation NRC SeniorResidentInspectorSurryPowerStation Serial Number 08-0275DocketNos.

50-305/336/423/338/339/280/281GL2004-02;RequestforExtensions Page 6 of 6 cc: (continued)Ms.M.H.ChernoffNRCProject Manager-KewauneeU.S.Nuclear Regulatory CommissionOneWhiteFlintNorthMaiIStop 0-8 H4A 11555RockvillePike Rockville, Maryland 20852-2738 Mr.J.D.HugheyNRCProject Manager-MillstoneUnits2and3U.S.Nuclear Regulatory CommissionOneWhiteFlintNorthMaiIStop 0-8 83 11555RockvillePike Rockville, MD 20852-2738Mr.S.P.LingamNRCProject Manager-SurryandNorthAnnaU.S.Nuclear Regulatory CommissionOneWhiteFlintNorthMaiIStop 0-8 G9A 11555RockvillePike Rockville,Maryland20852 Seria.lNo.08-0275DocketNo.50-305 ATTACHMENT 1 NRC GENERIC LETTER 2004-02 POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATIONDURINGDESIGN BASIS ACCIDENTS AT PRESSURIZED-WATER REACTORS REQUESTFORANEXTENSIONOFTHE COMPLETION DATE FOR CORRECTIVE ACTIONSDOMINIONENERGY KEWAUNEE, INC.(DEK)KEWAUNEE POWER STATION Seria.lNo.08-0275DocketNos.50-305 Attachment 1Page1 of 10RequestforanExtensionoftheCompletionDateforCorrectiveActionsKewauneePowerStation1.0BackgroundDuringtheensuingworktocompletetheGenericLetter(GL)2004-02correctiveactions,itbecameapparentthatcertainactivitiesrequiredtoaddressthecontainmentsumprecirculationissuescouldnotbecompletedbyDecember31,2007.ForKewaunee,theseactivitiesincludeddownstreameffectsevaluationsforcomponentwearandsystemperformanceandfornuclearfuelandthereactorvessel,aswellascompletingstrainerperformancedocumentationinsupportofchemicaleffectsresolution.Consequently,inaletterdatedNovember15,2007(SerialNo.07-0660),DominionEnergyKewaunee,Inc.(DEK)requestedanextensiontoJune30,2008tocompletetheoutstandingcorrectiveactions.InaletterdatedDecember13,2007,theNRCtookexceptiontoDEK'sextensionrequest.WhiletheNRCconfirmedthatadequatemitigationmeasureshadbeenputinplacetoreduceplantriskfortherequestedsix-monthextension,thestaffnotedthatgiventheimportanceofreachingpromptclosureofGL2004-02,theNRCexpectedKewauneetocompletecorrectiveactionsbyMay 31,2008.ThestaffalsostatedthatshouldDEKbeunabletocompletetheKewauneeGL2004-02correctiveactionsbyMay31,2008,additionaljustificationmustbeprovidedtotheNRCforanyrequestedextensionbeyondthatdate.1.1CurrentStatusofActivitiesDEKhasmadesignificantprogress regardingthecompletionofdownstreameffectsevaluationsandchemicaleffectsresolutionforKewaunee.DownstreamEffectsAsstatedinDEK'sGL2004-02supplementalresponsetothestaffdatedFebruary29,2008(SerialNo.08-0017),Kewauneeperformedaseriesofdownstreameffectsevaluationstoidentifyclearances,potentialforsystemblockageandcomponentwearintheSafetyInjection(SI),ResidualHeatRemoval(RHR)andInternalContainmentSpray(ICS)systems.InSeptember2007,WCAP-16406-P,"EvaluationofDownstreamSumpDebrisEffectsinSupportofResolutionof GSI-191,"wasrevisedtoprovideimprovedguidanceforperformingdownstreameffectsevaluationsforcomponentwear.Consequently,DEKhascompletedarevisiontoKewaunee'sdownstreameffectsevaluationsfortheSI,RHRandICSsystems.Therevisedevaluationsdidnotidentifytheneed

'foranyphysicalchangestoplantequipment.AnadditionaldownstreameffectsevaluationhasbeenpreparedusingWCAP-16793-NP,"EvaluationofLong-TermCoolingConsideringParticulate,FibrousandChemicalDebrisinthe RecirculationFluid,Revision0."Thenewevaluationconfirmsthequantityofchemicalprecipitantspostulatedtoplate-outonthefuelcladdingafteraLossofCoolantAccident(LOCA)willnotposeanadverseimpacton SerialNo.08-0275DocketNos.50-305 Attachment 1Page2of10theabilityofthecoolanttoremovedecayheatfromthecore.TheevaluationwascompletedonMay15,2008.AsstatedinDEK'sletterstothestaffdatedNovember15,2007,andFebruary29,2008,KewauneealsocontractedwithWestinghousetoperformadownstreameffectsevaluationforthereactorinternalsandnuclearfuel.TheevaluationconfirmedtheclearancesinKewaunee'sreactorinternalsfarexceedthesizeofdebristhatcouldbypassthestrainer;therefore,flowblockageinthereactorinternalsduetobypasseddebriswillnotoccur.Theevaluationalsoconfirmedthatthequantityoffiberthatcouldbypassthestrainerwouldnotformathinbedoffiberonthetopsupportgridofthecore.Kewaunee'sdownstreameffectsevaluationsarenowcomplete.ChemicalEffectsKewauneeisintheprocessofcompletingacomputationalfluiddynamics(CFD)analysisofthepost-LOCAsumppoolduringrecirculation.Thisactivityisinsupportofpreparationoftheupdatedstrainerperformance documentationforresolutionofchemicaleffects.PreliminaryresultsfromtheCFDanalysisrecentlyidentifiedthatflowratesoveroneofKewaunee'sthreedebrisinterceptorsisinexcessoftheflowratesusedduringdebrisinterceptortesting.Therefore,anadditionalflumetestwillbeperformedusingthenewanalyzed sumppoolflowtoreconfirmthat transportofdebristothestrainerremainssufficientlylowandresultsincleanstrainersurfaces.Cleanstrainersurfaceswillprevent increasedstrainerheadlossduetochemical precipitantsintherecirculationfluidandwillresolvetheissueofchemical effects,.DEKisrequestingascheduleextensiontocompleteanadditionalstrainer/debris interceptorflumetestandtoupdatethestrainerperformanceandlicensingbasis documentation tocompleteresolutionofthechemicaleffectsissue.TheCFDanalysisisinprogressandwillbecompletebyJune15,2008.Preliminaryplanningforthenextstrainer/debrisinterceptortestisinprogressatthistime.FollowingcompletionoftheCFDanalysis,thestrainer/debrisinterceptorTestPlanwillbefinalizedandtestingwillbeperformed.AnextensionisrequestedtoSeptember30,2008tocompleteanadditional strainer/debris interceptorflumetestandtoupdateKewaunee'sstrainerperformance documentationandlicensingbasis.Thesefinalcorrectiveactionswillcompleteresolutionofchemicaleffectsand GL.2004-02activities.RequiredphysicalchangestotheplanthavebeencompletedandareaddressedinDEK'slettertothestaffdated February 29,2008.Inthefollowingdiscussion,DEKhasaddressedthe"CriteriaforEvaluatingDelayofHardwareChanges,"asdescribedinSECY-06-0078datedMarch31,2006,asthefoundationforthisextensionrequest.AnextensionisrequestedtoSeptember30,2008 SerialNo.08-0275DocketNos.50-305 Attachment 1Page3of10tocompletethefinalstrainerperformancetestinganddocumentationforresolutionofchemicaleffects.TheproposedextensionforKewauneedoesnotaltertheoriginalconclusionssummarizedinGL2004-02inwhichthestaffdeterminedthatitisacceptableforPWRlicenseestooperateuntilthecorrectiveactionsarecompletedbecauseofsufficientlylowplantrisk.2.0Justificationforthe ExtensionTheNRCprovidedajustificationforcontinuedoperation(JCO)inthe"SummaryofJuly26-27,2001MeetingwithNuclearEnergyInstituteandIndustryonECCSStrainerBlockageinPWRs,"datedAugust14,2001,thatsupportscontinuedoperationthroughDecember31,2007.Elementsof theJCOthatcontinuetobeapplicabletoKewauneeincludethefollowingitems:*TheKewauneecontainmentiscompartmentalizedmakingtransportofdebristothesumpdifficult.*Theprobabilityoftheinitiatingeventisextremelylow(largeandintermediatebreakLOCAandsmallbreakLOCArequiringrecirculation).

• Leak-Before-Break(LBB)qualifiedpipingisofsufficienttoughnessthatitwillmostlikelyleak(evenundersafeshutdownconditions)ratherthanrupture.*KewauneeisnotsusceptibletoprimarywaterstresscorrosioncrackingassociatedwithpressurizerAlloy600/82/182dissimilarmetalweldssincetheKewauneepressurizerdoesnotcontainthesetypesofwelds.*Thetimetoswitchovertorsclrculatlonfromthesumpafteraccidentinitiationallowsfordebrissettling.*Nocreditistakenforcontainmentoverpressureinthenetpositivesuctionhead(NPSH)analysesfortheRHRsystemintherecirculationmode.*ThereplacementEmergencyCoreCoolingSystem(ECCS) strainerinstalledin October2006wasdesignedtoincludemarginforparticulate,fibrousandchemicaldebris.*5.8feetofnetpositivesuctionhead(NPSH)marginisavailablefortheRHRpumpswhenoperatinginthecontainmentsumprecirculationmodewiththenewECCSrecirculationstrainerarrangementandthemaximumallowedstrainerheadloss(10feet).Strainerperformancetestingandcalculationsusing NUREG/CR-6224 show greatHrmarginisavailable.

SerialNo.08-0275DocketNos.50-305 Attachment 1Page4of10 3.0 Reasonforthe Proposed Extenalon 3.1 Chemical Effects ResolutionDEK'slettertothestaffdatedFebruary29,2008,summarizesKewaunee"schemicaleffectsresolutionactivities.Significantefforthasbeenexpendedinresolvingthisissue.Chemicalprecipitationanalyses arecomplete,asindicatedintheFebruary29,2008 letter.Strainerflumetestinghasbeenperformed,includingdebris transportflumetestswiththestrainerdebrisinterceptorsmodeledintheflume.Additional strainer/debrisinterceptortestplanningisinprogressusingtheresultsofarecentCFDanalysis.Theadditionaltestisexpectedtoverifythequantityofdebristhatcan transporttothestrainerisinsufficienttoformathin orthickbedofdebrisonthestrainer.Kewauneehasalowfibrous debrisloadduetothelargemajorityofreflectivemetalinsulationonpipingandequipmentintheReactorCoolantSystem(RCS)andECCS,andcloseproximitysystems.ACFDanalysisisbeingperformedtosupportarefinedGSI-191debristransportevaluation.FollowingcompletionoftheCFDanalysis,anadditionalstrainer/debrisinterceptortestwillbeperformedandthestrainerperformance documentationandlicensing basiswillbeupdated.Thefinalflumetestingand documentationupdateswillcompleteresolutionoftheoutstandingchemicaleffects issue.DelaysincompletingthisactivitycanbeattributedtoadelayinobtainingasuppliedCFDanalysis.TherecentCFDpreliminaryresultsrevealedhigherflowratesoveroneofthreedebrisinterceptors.Theflowrateoverthesouthdebris interceptorexceedstheflowratesusedindebristransportflumetestsconductedin2007.Consequently,thedebristransportflumetestsperformedin2007arenotboundedbytheresultsofthenewCFDanalysis.Therefore,anadditionalflumetestwillbeperformedattheflowratesidentitledbytheCFDtoconfirmthequantityofdebrisexpectedto transporttothestrainerandtheresultantimpactonthestrainerheadloss.KewauneehasbeenanactiveparticipantinthePerformanceContracting,Incorporated(PCI)SureFlowStrainerUsersGroup(SFSUG)andtheSFSUGlargescaleflumetestingeffort.Therefore,KewauneeispreparedtobegintestingassoonastheSFSUGtestflumeisavailable.ThecurrentSFSUGtestscheduleforthelargescaletestflumeindicatesKewaunee'stestingcancommenceapproximatelyJuly 7,2008.ThevendorssupportingKewaunee'sGSI-191resolutionaresupportingmultiplepressurizedwaterreactor(PWR)unitswithGSI-191resolutionconcurrently.Kewauneestaffhasmadesignificantefforttoprovidetimelyinputsandtimelyreviewsforsupplieddocumentstoexpedite thisworkasmuchaspossible.TheimportanceofcompletingtheseactivitiesinatimelyfashioniswellunderstoodbyDEKandthevendor staffinvolvedincompletingKewaunee'sGSI-191resolution.Themajorityofthe191resolutionactivitiesforKewauneehavebeencompleted.ThefinalresolutionisnearingcompletionandwillbecompletedbySeptember30,2008.

SerialNo.08-0275 DocketNos.50-305 Attachment 1Page5of10 3.2 Extension RequestDEKisrequestinganextensionuntilSeptember 30,2008forcompletionofthefollowing activities:1.Completethepost-LOCAcontainmentsumppoolCFDanalysis.2.CompletestrainerperformancetestinganddocumentationthatconfirmsKewaunee'slowfiberquantityandcontainmentsumppool transportcharacteristicsdonot resultinathinorthickbedofdebrisonthesumpstrainer.Consequently,cleanstrainersurfacesareexpectedtoremainandtherewillbenoincreasedstrainerheadlossduetochemical precipitants inthesumppool.3.FollowingcompletionoftheCFDanalysisandstrainerperformancetestinganddocumentation,theKewauneeUpdatedSafetyAnalysisReport(USAR)willbeupdated.

4.0 Compliance

withSECY-06-0078 Criteria SECY-06-0078specifiestwocriteriaforshortdurationGL2004-02extensions,limitedtoseveralmonths,andathirdcriterionforextensionsbeyondseveralmonths.ThesethreecriteriaandtheassociatedresponsesforKewauneeareprovidedindetailbelow.4.1SECY-06-0078 Criterion No.1:Thelicenseehas aplant-specifictechnical/experimentalplanwithmilestonesandscheduletoaddressoutstandingtechnicalissueswithenoughmargintoaccountfor uncertainties.DEKResponseKEWAUNEEPLANT-SPECIFIC TECHNICAL/EXPERIMENTAL PLANInaccordancewithKewaunee'sPlant-SpecificPlan,outlinedinDEK'sextensionrequestletterdatedNovember15,2007,DEK'sGL2004-02supplementalresponsedatedFebruary29,2008,andinformationpresentedinthisletter,thefollowingtaskshavebeencompleted:*Debrisanalyses oDebrisgenerationanalyses oChemicalprecipitantanalyses Seria.lNo.

08-0275DocketNos.50-305 Attachment 1Page6of10*Downstreameffectsanalyses oNuclearfuelandreactorvesseldownstreameffectsevaluations.

oDebrisblockage,componentwearandsystemperformancedownstreameffectsanalysesforcomponentsintheSI, RHRandICSsystems.*Strainerheadloss,vortexevaluations,initialstrainer/debris interceptor debris transportandstrainerheadlossflumetesting,andapreliminaryCFDanalysis.*Replacementstrainerdesign and installation.Tocompletethiseffortandadopt thHlicensingbasisrequiredforlong-termcorecoolingrequiredforresolutionof GSI-191atKewaunee,thefollowingmilestonesaretobemet:

June 15,2008 September 30,2008 Complete,thepost-LOCAcontainmentsumppoolCFD analysis.Completestrainerperformancetestingand documentation,andprepareandapproveanupdatetotheKewaunee USAR.Basedontheabovediscussion,KewauneemeetstherequirementsofSECY-06-0078Criterion1.4.2SECY-06-0078 Criterion No.2:Thelicenseeidentifiesmitigativemeasurestobe putinplacepriortoDecember 31, 2007, and adequatelydescribeshowthesemitigativemeasures willminimizetherisk ofdegradedEGGS[emergencycorecoolingsystem]functionsduringtheextension period.DEKResponseTodate,thefollowingmitigativemeasureshavebeenimplementedtominimizetheriskofdegradedECCSfunctionsduringtherequestedextensionperiod.Although SECY-06-0078 Criterion No.2specificallymentionsacompletiondateofDecember31,2007,DEKwas previouslygrantedanextensionuntilMay31,2008tocompleteGL2004-02correctiveactions(referenceNRCletterdatedDecember13,2007).ThefollowingmitigativemeasurespertaintothecurrentrequestforextensiontoSeptember 30,2008: 4.2.1 Mitigative MeasuresDEKisfullycommittedtoresolvingtheissuesassociatedwithGSI-191andiscontinuingeffortstocompletethecorrectiveactionsasdiscussedinourFebruary29,2008supplementalresponsetoGL2004-02.Requiredphysicalmodificationshavebeencompleted.

SerialNo.08-0275DocketNos.50-305 Attachment 1Page7of101.Physical Modifications As discussed in greaterdetailinDEK's February29,2008lettertothestaff,physical modifications included installationofanew, passive, safety-related Sure-Flow strainer designed by Performance Contracting, Incorporated(PCI).The modification included installing debris interceptorsaroundthe strainer to prevent debris travelingalongthesump floorfromreachingthestrainer'sperforatedmaterial.The modification also includedachangetothenarrowrangesumplevel instrument float columns to prevententryofdebnsexceedingthe strainer perforationsizeintothe recirculation sump.Downstream effects evaluationsforthereactorvesseland nuclearfuelandSI,RHRandICS systemsarecomplete.Noadditional modificationsarerequired.

2.Containment CleanlinessDEKhas proceduresinplacetoensure containment cleanlinessandto quantify potential debrissources.The procedures are describedinDEK'sletterstothestaff dated November15,2007andFebruary 29,2008.3.Procedural Guidance.Training,andActions OperatorsaretrainedandhaveguidanceformonitoringECCSpump parameters includinglossofNPSHas indicatl3dbyerraticpump current or discharge flow.4.Information Notice 2005-2El On September16,2005,theNRCissuedInformationNotice(IN) 2005-26,"Results of ChemicalEffectsHeadLossTestsina SimulatedPWRSumpPool Environment." IN 2005-26 appliestoplantswithcalciumsilicate insulation and trisodium phosphateasabuffer.

Kewauneedoesnotusetrisodium phosphateasitsbuffer.

Therefore, no responsetoIN 2005-26wasrequiredforKewaunee.5.Risk EvaluationWiththe installationofthenew containment recirculation sump strainer, revised programmatic controls, and evaluations performedtodate, Kewaunee has significantlyreducedthe vulnerabilitytodebris blockageinthe recirculation system when mitigatingaLOCA.DEK's extensionrequestforKewauneedated November15,2007 providedarisk evaluationfora six-month extension,Therisk evaluationisrepeatedinthe following paragraphsandadjustedfor tho additional extension to September30,2008to completetheremaining G81-191resolutionactivities.

SerialNo.08-0275 DocketNos.50-305 Attachment 1Page8of10Withtheinstallationoftheadvancedsumpstrainerdesign,debrisinterceptors,andotherassociatedchangesandevaluations,therehasbeenasignificantreductioninthevulnerabilitytodebrisblockageandcomponentwearintherecirculationsystemwhenmitigatingaLOCA.Forthe remainingoutstandingissuerelatedtochemicaleffects,thevulnerabilityis limitedtolargebreakLOCAsonly.ForsmallandintermediatebreakLOCAs,itisexpectedthattherewillbeasignificantreductionindebrisgeneration,asmuchas onetotwoordersofmagnitude.Withthistypeofreductioninthefibrousandparticulatesources,corecoolingwillbeassuredforsmallandintermediatebreakLOCAs.Sincetheadvancedstrainerdesignissizedforaconservativeestimateof thefibrousdebrisloadingfromalargebreakLOCA,itisexpectedthatforfibrous debrisloadingsthatareanorderofmagnitudeormorelower,therewillalsobeopenscreenareasuchthatanychemicalprecipitantsthataregeneratedwillnotpreventflowthroughthestrainerandadequateNPSHwillbemaintained.Thequantitative riskevaluationaddressespotentialvulnerabilityforlargebreakLOCAsonly.Theprobabilityofthisinitiatingeventislow(5.0E-6/yr).TheincreaseinCoreDarnaqeFrequency(CDF)andLargeEarlyReleaseFrequency(LERF)isdeterminedfromtheinitiatingeventfrequencyforalargebreakLOCA.Integratingtheinitiatingeventfrequencyovertheperiodoftheproposedninemonthextension(i.e.,fromDecember31,2007toSeptember30,2008)calculatestheCoreDamageProbability(COP)andtheLarge,EarlyReleaseProbability(LERP).Asnotedabove,theinitiatingeventfrequencyforaLBLOCAisequalto5.0E-6/yr.Therefore,foraninemonthextensiontocompleteGL2004-02correctiveactions,theCOPiscalculatedasfollows:

COP=(5.0E-6/yr)*(0.75 years)COP=3.75E-6TheLERPisthenequalto3.

75E**7.Thisvalueisdeterminedbyusingthe0.1factorforcontainmentperformancethatistypicallyassumedforqualitativelarge,earlyreleaseestimates.Nocreditistakenforrecoveryactions,whichKewauneewouldnormallyutilize,toensureconservativeresults.

ThebaseCDFandbaseLERFvaluesforKewauneeareshownbelowalongwiththeCOPandLERPvaluesthatwerecalculatedfortheproposedninemonthextension.BaseCOFCOPfor9monthBaseLERFLERPfor9month extension extension 7.60E-5/yr 3.75E**6 9.80E-6/vr 3.75E-7RegulatoryGuide(RG)1.174statesthat,whencalculatedchangesinriskareintherangeof1 E-6/yrto1E-5/yr,apermanentchangeis"small"ifthetotalCDFislessthan1E-4/yr.ForLERF,a"small"changeisacalculatedriskincreaseintherangeof1E-7/yrto1 E-6/yrifthetotalLERFislessthan1E-5/yr.ThisRGsetscriteriafor Serial No.08-0275DocketNos.50-305 Attachment 1Page9of10permanentplantchangeswith a.ssociatedriskincreases.Inthiscase,itmaybeconservativelyusedtoevaluatetheriskimpactoftheninemonthextensiontocompletetheGL2004-02correctiveactions.Theassumptionthatthesumpis100%unavailableisadditionally conservative.Therefore,basedonRG1.174,theproposedadditionalextensiontoSeptember30,2008tocompletetheGL2004-02correctiveactionsforKewauneeisacceptable.6.SafetyFeaturesandMarginsinCurrentConfiguration/DesignBasisTherearedesignfeaturesthatfacilitatemitigationofthisissue.KewauneehaspreviouslyreceivedNRCapprovaltoinvoketheleak-before-breakmethodologytoeliminatethedynamiceffects(pipewhipandjetimpingement)ofapostulatedruptureoftheRCSpiping(hotleg,coldleg,crossoverpiping,pressurizersurgepipingandpipingconnectedtotheRCS)fromthedesignbasisoftheplant.Theapprovalwasbasedontheconclusionthattheprobabilityislowthatapipefailureoccursbeforenoticeableleakagecouldbedetectedandtheplantcanbebroughttoasafeshutdowncondition.Whileleak-before-breakisnotbeingusedtoestablishthedesignbasisdebrisloadontheECCSrecirculationstrainer,itdoesprovidefurtherbasisforsafecontinuedoperationuntilthecompletionoftheGL2004-02correctiveactions.Basedontheabovediscussion,KewauneemeetstherequirementsofSECY-06-0078Criterion2.4.3SECY-06-0078Criterion3:

For proposedextensionsbeyondseveralmonths, alicensee'srequest willmorelikelybeacceptediftheproposedmitigativemeasuresincludetemporaryphysicalimprovementstothe EGGSsumpormaterialsinsidecontainmentto better ensure ahighlevel ofEGGSperformance.DEKResponseAsnotedinSection 4.2.1above,DEKhascompletedtherequiredphysicalmodificationstotheplantforresolutionof GSI-191atKewaunee.Themodificationsincludedinstallationofanew,passive,safety-relatedSure-FlowstrainerdesignedbyPCI.Themodificationalsoincludedinstallanonofdebrisinterceptorsaroundthestrainertopreventdebristravelingalongthesumpfloorfromreachingthestrainer'sperforatedmaterial.Amodificationwasalsomadetothenarrowrangesumplevelinstrumentfloatcolumnstoprevententryof debrisintothesumpthatwouldexceedthestrainerperforationsize.Basedontheabovediscussion,KewauneemeetstherequirementsofSECY-06-0078Criterion3.

SeriallNo.08-0275DocketNos.50-305 Attachment 1Page10of10 5.0 ConclusionAnextensionoftheKewauneecompletiondatefromMay31,2008to September 30,2008tocompletetheremainingcorrectiveactionrequiredbyGL2004-02is acceptable because:*Theinitiatingeventandlarge,earlyreleaseprobabilitiesforKewaunee associatedwiththeninemonthextension(fromDecember 31,2007)are3.75E-6andnegligible,respectively.Thisriskimpactischaracterizedas"small"perNRGRegulatoryGuide 1.174.*DEKhascompletedconsiderablephysicalandanalyticalactivitiestoprovideahighlevelofEGGSperformanceincludingreplacingtheEGGSrecirculationstrainer.*DEKhas implementedmitigativemeasurestominimizetheriskof degraded EGGS functionsduringtheextensionperiod.*DEKhasa plant-specificplanwithmilestonesandschedulestoaddressthe outstandingtechnicalissueswithsufficientconservatismtoaddress uncertainties.

Therefore,perthecriteriaincludedinSEGY-06-0078,DEKhas establishedthattherisk of degradedEGGSfunctionsforKewauneeisnotconsideredtobesignificant.

SerialNo.08-0275 Docket Nos.50-336/423 ATTACHMENT 2 NRC GENERIC LETTER 2004-02 POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATIONDURINGDESIGN BASIS ACCIDENTS AT PRESSURI:ZED-WATER REACTORS REQUESTFORANEXTENSIONOFTHE COMPLETION DATE FOR CORRECTIVE ACTIONS DOMINION NUCLEAR CONNECTICUT, INC.(ONC)MILLSTONE PO'IVER STATIONUNITS2AND3 SerialNo.08-0275DocketNos.

50-336/423 Attachment 2Page1of11RequestforanExtensionof ltheCompletionDatefor Corrective ActionsMillstonePowerStationUnits2and31.0BackgroundCorrectiveactionsthataddresscontainmentsumpperformanceandcompliancewiththeregulatoryconsiderationsofNRGGenericLetter(GL)2004-02forMillstonePowerStationUnits2and3wereinitiallyscheduledtobecompletebyDecember31,2007.Duringtheeffortstocompletethecorrectiveactions,itbecameapparentthatsomeactionscouldnotbecompleted byDecember31,2007.Theseactionsinclude downstream effects evaluations for componentwearandsystem performanceandfornuclearfuelandthereactor vessel,aswellas chemical effects testing and evaluation.Consequently,inaletterdatedNovember15,2007(SerialNo.07-0660),DominionNuclearConnecticut,Inc.(DNC)requestedanextensiontoNovember30,2008tocompletetheoutstandingcorrectiveactions.However,inaletterdatedDecember13,2007,theNRCtookexceptiontoDNC'sextensionrequest.WhiletheNRCconfirmedthatadequatemitigation measureshadbeenputinplacetoreduceriskfortherequestedelevenmonthextension,thestaffalsonotedthatDNC'srequestedextensiondatewasnotreasonablebasedon thecaseprovided.DuetotheimportanceofpromptclosureofGL2004-02,theNRCgrantedDNCanextensiontoMay31,2008tocompletetheoutstandingcorrectiveactionsforMillstoneUnits2and3.However,thestaffalsostatedthatshouldDNCbeunabletocompletetheMillstoneGL2004-02correctiveactionsbyMay31,2008,additional justificationmustbeprovidedtotheNRCforanyrequestedextensionbeyond tlhat date.Asdiscussedingreaterdetailbelow,DNChasmadesignificantprogressregardingthecompletionofdownstreameffectsevaluationsandchemicaleffectstestingand evaluation.*DownstreamEffects-Downstreameffectsevaluationsarerequiredtodetermine:1)theeffectofdebris ladenwateronthe reactor vesselandfuel assemblies, and2)componentwearduetotheeffectsofdebrisandtheresultanteffect,ifany,onsystemperformanceduetopotentlallydegradedcomponents.ComponentwearevaluationsandanevaluationoftheabilityoftheEmergencyCoreCoolingSystem(ECCS)pumpsealstowithstandpumpingdebrisladenwaterwithoutexcessiveleakageandhydraulicimpactonthepumpsareinprogress.

• Chemical Effects-Benchtop testinghasbeen completedtodeterminethe solubility/precipitatebehaviorof HIe chemicals expectedtoexistinthecontainmentsumpasaresultofalossofcoolantaccident(LOCA).Inaddition,aconservativereducedscaletestisin progress(seeitem3.3below).DNCandtheNRChaveconductedstatusupdateconferencecallsassociatedwithchemicaleffectstestingprogress,andthestaffhas reViE!Wedandcommentedonthetestingprotocolsforbenchtop,singleloopandmulti-looptestingpreparedbyAtomicEnergyofCanada,Limited(AECL,thechemicaleffectstestingvendor).Furthermore,thestaffhas SerialNo.08-0275 Docket Nos.50-336/423 Attachment2Page2of11witnessedcertainmulti-looptestingactivitiesatAECL'sChalkRiverTestFacility.EventhoughconsiderableproqresshasbeenmadetoaddresstheremainingGL2004-02correctiveactions forMillstoneUnits2and3,certainchemicaleffectstestingactivitiescannotbecompletedbyMay31,2008.Specifically,completionofongoingreducedscalemulti-looptestingusingMillstone plant-specific chemicalconditionsisrequiredtodeterminecontainmentsumpstrainerheadloss.Reviewoftestresultsand finalizationoftest documentationwillbecompletedfollowingtesting.Therefore,DNCisrequestingascheduleextensionforMillstoneUnits2and3tocompletetheremainingchemicaleffectstesting,testreports,andlicensingbasisupdates,aswellastodeterminewhetheranyadditionalactionsmayberequiredbasedontheresultsofthe testinq,TheinformationinthebalanceofthisattachmentprovidesarequestandbasisforextendingthiscorrectiveactionsscheduletoSeptember30,2008.Specifically,DNChasaddressedthe"CriteriaforEvaluatingDelayofHardwareChanges,"asdescribedin SECY-06-0078datedMarch31,2006.ThisdiscussionsupportsDNC'srequestforanextensionofthecorrectiveactionscompletiondatetoensurethatthenecessarytestingandtestreportshavebeencompletedandthesupportingcalculationshavebeenreviewedandvalidatedtofacilitateresolutionoftheGenericSafetyIssue(GSI)-191.Anextensionto September30,2008isrequestedtoallowcompletionoftheremainingrequiredactionsdiscussedbelowandtoupdatethelicensingbasisdocuments.TheproposedextensionforMillstoneUnits2and3doesnotaltertheoriginalconclusionssummarizedinGL2004-02inwhichthestaffdeterminedthatitisacceptableforPWRlicenseestooperateuntilthe correctiveactionsarecompletedbecauseofsufficientlylowplantrisk.

2.0 Justificationforthe

Proposed ExtensionTheNRCprovidedajustificationforcontinuedoperation(JCO)inthe"SummaryofJuly26-27,2001MeetingwithNuclearEnergyInstituteandIndustryonECCS StrainerBlockageinPWRs"datedAugust14,2001,thatsupportscontinuedoperationthroughDecember31,2007.ElementsoftheJCOthatcontinuetobeapplicabletoMillstoneUnits2and3includethefollowing:*BothMillstoneUnits2and3 containments are compartmentalized,thusslowing transportofdebristothesump.*Theprobabilityoftheinitiatingevent(Le.,largebreakLOCA)isextremelylow.

• Leak-Before-Break(LBB)qualifiedpipingisofsufficienttoughnessthatitwillmostlikelyleak(evenunder safeshutdownconditions)ratherthanrupture.*Thetimeforswitchoverto recirculationfromthesumpafteraccidentinitiationallowsfordebrissettling.

SerialNo.08-0275 Docket Nos.50-336/423 Attachment 2Page3of11 3.0 Current Status and Reason for the Proposed Extension 3.1 Downstream Effects-Fueland Reactor Vessel WCAP-16793-NPRev.0,"EvaluationofLong-TermCoolingConsideringParticulate,FibrousandChemicalDebrisintheRecirculationFluid,"providesthecriteriafor performing downstreameffectsevaluationsregardingcoreeffects.Thisevaluationhasbeencompletedandconcluded that*AdequateflowtoremovedecayheatwillcontinuetoreachthecoreevenwithdebrisfromthesumpreachingtheReactorCoolantSystem(RCS)andcore,*Decayheatwillcontinuetoberemovedevenwithdebriscollectionatthefuel assembly spacer grids,*Fibrousdebris,shoulditenterthecoreregion,willnottightlyadheretothesurfaceoffuelcladding,*Simulatinglargedebris loadinqsoffiberglassandcalciumsilicate,decayheatwillberemoved,andacceptablefuelclad temperatureswillbemaintained,and*Asblockageofthecorewillnotoccur,thecalculationsthat demonstrate appropriateboricaciddilutiontoprecludeboricacidprecipitationremainvalid.

Unit-specificcalculationswereperformedtodeterminetheexpected deposition ofchemicalsonthefuelanddemonstratedthattheWCAP evaluations and conclusions are directlyapplicabletoMillstoneUnits2and3.Consequently,thereisreasonableassurancethatlong-termcore coolingforMillstoneUnits2and3willbe established and maintained post-LOCAevenwhenconsideringthepresenceofdebrisintheRCSand core.Referto Millstone'sSupplementalResponsetotheNRC,datedFebruary29,2008(SerialNo.07-0797,ADAMSML080650561), Attachments1and2(Sections3N),foramoredetailedtechnicaldiscussionoftheevaluation.Thiseffortiscomplete.No extensionisrequiredforthiseffort.

3.2 Downstream

Effects-Component Wear and System PerformanceWCAP-16406-PRev.1,"Evaluation ofDownstreamSumpDebrisEffectsinSupportofResolutionofGSI-191,"provides revisedguidancefortheperformanceof downstream effects evaluations for component wear and resulting system performance with potentially degraded components.

The resultantreviseddownstreamcomponentweareffectsevaluationsareinprogress forMillstoneUnits2and3.Theseevaluationsareexpectedtobecompleteand reviewedbyJuly 31,2008.SystemperformanceevaluationsusingtheinformationfromthewearevaluationsareexpectedtobecompletedbyAugust15,2008.

SerialNo.08-0275 Docket Nos.50-336/423 Attachment 2Page4of11 3.3 Strainer Debris and Chemical TestingCompletionofchemicaleffects testiingandevaluationisrequiredtoconfirmthatthereplacementstrainersinstalledatMillstoneUnits2and3areadequatetomaintainNPSHmarginfortheECCSpumpsduringlong-termcorecoolingandtoconfirmthatnofurtherphysicalmodificationsarerequired.AchemicaleffectsevaluationiscurrentlybeingperformedforMillstoneUnits2and3byAECLtodeterminethepotentialforchemicalprecipitateformation.Publishedindustrydatawerecollected, consolidated,anddepictedasaseriesoftemperature dependentcurvesplottedona pH/precipitateconcentrationgraph.Benchtoptestingwasperformedtoconfirmthevalidityofthecurves,thusprovidinganaccurateindicationofwhenprecipitateformationwouldbeexpectedtooccur.Benchtoptestingiscomplete,anduponreceiptofthetestreportfromAECL,DNCwillbeginitsinternalreview.Multi-looptestingwillprovideameansofperformingnumerous(i.e.,six)reducedscaletestssimultaneouslyfortheDominionunits.MillstoneUnits2and3strainerswillbetestedwithMillstoneplantspecificfibrousandparticulatedebrisloadsandchemicalconditionsthatwouldbeexpectedtobeinthecontainmentsumpfollowingaLOCA.Eachtestwillbeperformedfor30-daysfollowingtheformationofathin-bedofdebrisataspecifiedtemperatureandflowratetorep roducethepossibilityofprecipitateformationanditsresultingimpactonheadloss.TestingiscurrentlyscheduledtobecompletedbyJuly31,2008,withtheStrainerTestReportissuedbyAugust 31,2008.3.4 Extension RequestDNCisrequestinganextensionuntil September30,2008forcompletionofthefollowingactivities:

• Issuance and internalreviewof chemical evaluation and benchtop testing reports,*CompletionofECCSdownstreamcomponentwear,systemperformance,andpumpsealevaluations,*Completionofchemicaleffects reducedscaletesting,evaluation,andtestreportpreparationandreview,*Determination of whetheranyadditionalactionsarerequiredbasedontheresultsofthechemicaleffectstestingandevaluations,and*UpdateofdesignandlicensinqbasisdocumentstoreflecttheplantchangesimplementedtoresolveGSI-191issues.

SerialNo.08-0275DocketNos.

50-336/423 Attachment 2Page5of11 4.0 Compliance with SECY-06-0078 Criteria SECY-06-0078specifiestwocriteriaforshortdurationGL2004-02 extensionslimitedtoseveralmonthsandathirdcriterionforextensionsbeyondseveralmonths.ThesethreecriteriaandtheassociatedresponsesforMillstoneUnits2and3areprovidedindetail below.4.1 SECY-06-0078 Criterion No.1:Thelicenseehas aplant-specifictechnical/experimentalplanwithmilestonesandscheduletoaddressoutstandingtechnicalissueswithenoughmargintoaccountfor uncertainties.DNCResponseMILLSTONEPLANTSPECIFIC TECHNICAL/EXPERIMENTAL PLANInaccordancewithMillstone'sPlantSpecificPlan,outlinedinDNC'sextensionrequestletterdatedNovember15,2007(ADAMSML073190553),DNC'sGL2004-02 supplementalresponsedatedFebruary29,2008,andtheinformationcontainedinthisletter,thefollowingtaskshavebeencompleted:*Debrisanalyses oDebrisgenerationanalysesinaccordancewith WCAP-16568-P,Rev0(ZoneofInfluencedetermination)oDebris transport analyses*Downstreameffectsanalyses oFuelandvesseldownstreameffectsanalysesinaccordancewithNP,Rev.0*Strainerheadlossandvortextestingforexpecteddebrisload(excludingchemical precipitants).*Benchtoptesting(includingconsiderationof WCAP-16530-NPresults)todeterminelikelyprecipitateformationandboundingquantitiesofprecipitantstouseinreducedscaletesting.*Replacementstrainerdesignand installationforbothMillstoneUnits2and3.DownstreameffectsevaluationsandreducedscalechemicaltestingandresultsevaluationoftheimpactofpotentialchemicalprecipitantsonstrainerheadlossarecurrentlyunderwayandarescheduledtobecompletedbyAugust31,2008.Tocompletethiseffortandtoadoptthelicensingbasisrequiredforlong-termcorecoolingrequiredforresolutionofGSI-191atMillstoneUnits2and3,thefollowingmilestoneshavebeenestablished:

SeriallNo.

08-0275 Docket Nos.50-336/423 Attach ment 2 Page 6 of 11GL2004-02 CORRECTIVE ACTION MILESTONES Activity Milestone DateDownstreamwearcalculations

• DNCreviewandcommentJune18,2008

• IssuefinalcalculationJuly18,2008PumpsealwearevaluationsJuly31,2008Systemperformanceevaluations August 15,2008Strainerchemicaleffectsreducedscaletestingandevaluation

• CompletestrainertestingJuly31,2008

• AECLissueTestReport August 31,2008*DNCreviewandcommentSeptember15,2008

• AECLissueFinalStrainerTest September 30,2008 Report RevisiontoDesignChangeRecordSeptember15,2008 (OCR)Determinationofwhetheranyhardwareand/orproceduralmodifications are September 30,2008neededasaresultofthecompletionofthechemicalprecipitateheadlosstestinqBasedontheabove discussion,MillstoneUnits2and3meettherequirementsofSECY-06-0078Criterion1.

4.2 SECY-06-0078 Criterion No.2:Thelicensee identifiesmitigativemeesurestobe putinplace prior to December 31, 2007, and adequately describes howthesemitigative measures will minimizetherisk of degraded EGGS[emergencycorecooling system]functions during the extension period.

SerialNo.08-0275DocketNos.

50-336/423 Attachment 2Page7of11DNCResponseTodate,thefollowingmitigativemeasureshavebeenimplementedtominimizetheriskofdegradedECCSsystemfunctionsduringtherequestedextensionperiod.Although the SECY-06-0078CriterionNo.2specificallymentionsacompletiondateofDecember31,2007,DNChasbeengrantedanextensionuntilMay31,2008(NRCletterdatedDecember13,2007,ADAMSML073450594),andallofthefollowingmitigativemeasurespertaintothecurrentrequestforextensionto September30,2008:4.2.1MitigativeMeasuresDNCisfullycommittedtoresolvingtheissuesassociatedwithGSI-191andiscontinuingeffortstocompletethecorrectiveactionsasdetailedintheFebruary29, 2008 supplementalresponseto GIL2004-02.DNChasimplementedthephysicalmodificationsidentifiedbelowatMillstoneUnits2and3.RefertotheMillstoneUnits2and3GL2004-02supplementalresponsedatedFebruary29,2008for greaterdetailontheinformationprovidedbelow.1.PhysicalModificationsAsdiscussedingreaterdetailinSection4.3below,DNCcompletedtheinstallationofthereplacementstrainersystemsinUnits2and3.DNChasremovedcalciumsilicateinsulationfromUnit2looproomsasrequiredtoeliminatethepresenceofcalciumsilicatefromanypotentiallylimitingbreakzoneofinfluence.Unit3doesnothaveanycalciumsilicateinsulation.DNChasdelayedthestartoftheUnit3RecirculationSpray(RSS)pumpstoensuresufficientwaterisavailabletocompletelysubmergetheECCSstrainerpriortoRSSpumpstart.

2.Containment CleanlinessDNChasproceduresinplacetoensurecontainmentcleanlinessasdocumentedintheresponsetoNRCBulletin2003-01,"PotentialImpactofDebrisBlockageon EmergencySumpRecirculationatPressurized-WaterReactors."3.ProceduralGuidance,Training,andActionsOperatorsaretrainedandhaveforcontinuouslymonitoringECCSpumpparametersincludinglossofNPSHasindicatedbyerraticpumpcurrentordischarge flow.

SerialNo.08-0275 Docket Nos.50-336/423 Attachment 2Page8of11 4.InformationNotice2005-26 On September16,2005,theNRCissuedInformationNotice(IN)2005-26,"ResultsofChemicalEffectsHeadLossTestsinaSimulatedPWRSumpPoolEnvironment."IN2005-26appliestoplantswithcalciumsilicateinsulationandtrisodiumphosphateasabuffer.MillstoneUnit2 hasthiscombinationinitscontainment.RemovalofcalciumsilicatefromthelooproomsatMillstoneUnit2wasdoneaspartoftheresponsetothisNRCconcern.SinceMillstone3doesnothaveanycalciumsilicateinsulationinitscontainment,this INdoesnotapply.5.RiskEvaluationWiththe installationofthenew containment sump strainersandother associatedchangesandevaluations,therehasbeenasignificantreductioninthe vulnerabilitytodebrisblockageandcomponentwearintherecirculationsystemwhenmitigatingaLOCA.Fortheremainingoutstandingissueofchemicaleffects,the vulnerability islimitedtolargebreakLOCAsonly.ForsmallandintermediatebreakLOCAs,itisexpectedthattherewillbeasignificantreductionindebrisgeneration,asmuchasonetotwoordersofmagnitude.Withthistypeofreductioninthefibrousandparticulatesources,corecoolingwillbeassuredforsmallandintermediatebreakLOCAs.Sincethenewstrainerwasdesignedtohandlea conservatively estimatedquantityofthefibrousandparticulatedebrisloadingfromalargebreakLOCA,itisexpectedthatforparticulatedebrisloadingsthatareanorderofmagnitudeormorelower,therewillbeinsufficientparticulatetoformathin-bedonthereplacementstrainers,andtherewill potentiaillybeopenstrainerarea.Thus,itislikelythatanychemicalprecipitatesthataregeneratedwillnotcreateaheadlosslargerthanthetestedthin-bedhead 1055,forwhichthestrainerwasdesigned,andadequateNPSHwillbemaintained.Furthermore,withanorderofmagnitudeormorereductionintheparticulatedebris,theparticulatedebrisconcentrationshouldbelowenoughsuchthatwearofdownstreamcomponentswouldbelimitedtothepointthatthereisreasonableassurancethatthe ECCSpumpsanddownstreamcomponentswouldcontinuetoprovideadequate corecooling.Thus,thequantitativeriskevaluationaddressespotentialvulnerability forlargebreakLOCAsonly.Theprobabilityofthisinitiatingeventislow(5.0E-6 foroneyearor3.75E-6forninemonths)andtheprobabilityofalarge,early releasleisnegligible.DNC'spreviousextensionrequestdatedNovember15,2007providedariskevaluationforanelevenmonthextension.TheNRCrepliedintheirresponseletterdatedDecember13,2007, withasummaryparagraphassociatedwiththerisk evaluation:"DominionprovidedariskevaluationforMillstone2andMillstone3,whichcomparedtheincreaseinCoreDamageFrequency(CDF)andLargeEarlyReleaseFrequency(LERF)fromalarge-breakLOCAtototalplantCDFandLERFriskvaluesandshowedthatthesevaluescouldbecategorizedas SerialNo.08-0275DocketNos.

50-336/423 Attachment 2Page9of11"small"inaccordancewiththecriteriastatedinRegulatoryGuide1.174,'AnApproachforUsingProbabilisticRiskAssessmentinRisk-InformedDecisionsonPlant-SpecificChangestotheLicensingBasis.'"DNC'scurrentrequestfor extensionisforninemonths,whichisenvelopedbytheelevenmonthriskassessmentreferencedabove.6.SafetyFeaturesandMarginsinCurrentConfiguration/DesignBasisDNChasNRCapprovaltoinvoketheleak-before-break(LBB)methodologytoeliminatethedynamiceffects(pipewhipandjetimpingement)ofpostulatedprimarycoolantpipingrupturesfromthedesignbasisoftheplant.ForMillstoneUnit2,thelicensinpbasisincludesapprovedLBBanalysisforthehotlegs,coldlegs,andcrossoverlegsoftheReactorCoolantSystem(RCS),thepressurizersurgeline,andportionsoftheSafetyInjection(SI)andShutdownCoolinglines,whicharenotisolablefromtheRCSpiping.ForMillstoneUnit3,theplant licensingbasisincludesapprovedpartialLBBanalysisforthehotlegs,coldlegs,andcrossoverlegsoftheRCS.Theapprovalwasbasedon thE:!conclusionthattheprobabilityofapipefailurebeforenoticeableleakagecouldbedetectedandtheplantbroughttoasafeshutdownconditionissmall.Whileleak-before-breakisnotbeingusedtoestablishthedesignbasisdebrisloadonthesumpstrainers,itdoesprovideadditionalbasisforsafecontinuedoperationuntilthecompletionoftheGL2004-02corrective actions.7.ChemicalEvaluationsand Benchltop testingDNC'schemical evaluations have concluded that Millstone'schemicalsareexpectedtoremaininsolutionwiththe exceptionofthe potential formationofcalcium phosphate.Benchtoptestinghasbeen completed, providingempiricalchemistrydatawhicharespecifictotheMillstonepower station.Thisdata establisheswhatconditionsare requiredfortheexpected containment sump chemicalmixtoeitherremaininsolutionor precipitate out.Potentialcalciumsourcesincludefiberglass insulationandbareconcrete.Calciumhasbeen observedtoleachfromthesesourcesduringbenchtop testing.Basedontheabovediscussion,MillstoneUnits2and3meettherequirementsofSECY-06-0078Criterion2.

4.3 SECY-06-0078 Criterion 3:Forproposedextensionsbeyondseveralmonths, alicensee'srequest willmorelikelybeaccepted iftheproposedmitigativemeasuresincludetemporaryphysical SerialNo.08-0275 Docket Nos.50-336/423 Attachment 2Page10of11 improvementstothe ECCS sump or materials inside containment to better ensure a high level of EGGS performance.DNCResponseAsnotedabove,DNChasimplementedthefollowingpermanentphysical improvementstothe containmentsumpstobetterensureahighlevelofECCSandRecirculationSystem(RS)sumpperformance.

• Strainer InstallationDNCcompletedtheinstallationofreplacementstrainersystemsforbothunits.Thetotalsurfaceareaofthenew MiliistoneUnit2straineris approximately 6000 fe andthetotalsurfaceareaofthenewMillstoneUnit3straineris approximately 5000 ft2.*RSSPumpStartTimeChangeDNChasdelayedthestartof the!Unit3recirculationspray(RSS)pumpstoensuresufficientwaterisavailabletocompletelysubmergetheECCSstrainerpriortoRSSpumpstart.*InsulationReplacement/RemovalatMillstoneUnit2DNChasremovedcalciumsilicateinsulationfromMillstoneUnit2looproomsasrequiredtoeliminatethepresenceofcalciumsilicatefromanypotentiallylimitingbreakzoneofinfluence.Basedontheabovediscussion,MillstoneUnits2and3meettherequirementsof SECY-06-0078Criterion3.

5.0 ConclusionAnextensionoftheMillstoneUnits2and3completiondatesfromMay31,2008to September30,2008tocompletethecorrectiveactionsrequiredbyGL2004-02isacceptablebecause:*Theinitiatingeventandlarge,earlyreleaseprobabilitiesforMillstoneUnits2and3associatedwithaninemonthextension(fromDecember31,2007)are3

..75E-6andnegligible,respectively.Thisriskimpactischaracterizedas"small"perNRCRegulatoryGuide1.174.*ONehascompletedconsiderableworktofurtherpromoteahighlevelofECCSpumpperformanceincluding replacementstrainerinstallationatbothMillstoneUnits2and3.

Serial No.08-0275DocketNos.50-336/423 Attachment 2Page11of11*ONGhasimplementedmitigativemeasurestominimizetheriskofdegraded EGGSfunctionsduringtheextensionperiod.*ONGhascompletedchemicalevaluationsandbenchtoptests,andperformed downstream evaluationsforthecoreandfuelinaccordancewiththeapplicableWCAPrequirementsthatprovidereasonableassurancethatsufficientcorecooling wi IIbemaintained:*ONGhasa plant-specificplanwithmilestonesandschedulestoaddresstheoutstandingtechnicalissueswithsufficientconservatismtoaddressuncertainties.Therefore,perthecriteriaincludedin SEGY-06-0078, ONChasestablishedthattheriskofdegraded EGGSfunctionsforMillstoneUnits2and3isnotconsideredtobe significant.

SerialNo.08-0275 Docket Nos.50-338/339A,TTACHMENT3 NRC GENERIC LETTER 2004-02 POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATIONDURINGDESIGN BASIS ACCIDENTS AT PRESSURI:ZED-WATER REACTORS REQUESTFORANEXTENSIONOFTHE COMPLETION DATE FOR CORRECTIVE ACTIONS VIRGINIA ELECTRICANDPOWER COMPANY (DOMINION)

NORTH ANNA POWER STATIONUNITS1AND2 Serial No.08-0275DocketNos.

50-338/339 Attachment 3Page1of13RequestforanExtensionoftheCompletionDatefor Corrective ActionsNorthAnnaPowerStationUnits1and2 1.0 BackgroundDuringtheensuingworktocompletetheGL 2004-02correctiveactions,itbecameapparentthatcertainactivitiesrequiredtoaddressthecontainmentsumpissuescouldnotbecompletedbyDecember 31,:W07.Theseactivitiesincludeddownstreameffectsevaluationsforcomponentwearandsystemperformanceandfornuclearfuelandthereactorvessel,aswellaschemicaleffectstestingandevaluation.Consequently,inaletterdatedNovember15,2007(SerialNo.

07-0660),DominionrequestedanextensiontoNovember30,2008tocompletetheoutstandingcorrectiveactions.However,inaletterdatedDecember13,2007,theNRCtookexceptiontoDominion'sextensionrequest.WhiletheNRCconfirmedthatadequatemitigationmeasureshadbeenputinplacetoreduceplantriskfortherequestedelevenmonthextension,thestaffalsonotedthatDominion'srequestedextensiondatewasnotreasonablebasedonthecaseprovided.DuetotheimportancepromptclosureofGL 2004-02,theNRCgrantedDominionanextensiontoMay 31, 2:008tocompletetheoutstandingcorrectiveactionsforNorthAnnaUnits1and2.

However,thestaffalsostatedthatshouldDominionbeunabletocompletetheNorthAnnaGL 2004-02correctiveactionsbyMay31,2008,additionaljustificationmustbeprovidedtotheNRCforanyrequestedextensionbeyondthatdate.Asdiscussedingreaterdetailbelow,Dominionhasmadesignificantprogressregardingthecompletionofdownstreameffectsevaluationsandchemicaleffectstestingand evaluation.*DownstreamEffects-Downstreameffectsevaluationshavebeenperformedtodetermine:1)theeffectofdebrisladenwateronthereactorvesselandfuelassemblies,and2)componentwearduetotheeffectsofdebrisandtheresultanteffect,ifany,onsystemperformanceduetopotentiallydegradedcomponents.DetailsoftheevaluationresultsareprovidedinSections 3.1 and 3.2below.AnextensionisrequiredtocompleteDominionstaffreviewofthedownstreamcomponentwearandsystemsperformanceevaluationsandtofinalizetheassociateddocumentation.*ChemicalEffects-Bench-toptestinghasbeencompletedtodeterminethe solubility/precipitatebehaviorofthechemicalsexpectedtoexistinthecontainmentsumpasaresultofalossofcoolantaccident(LOCA).Theresultsofthebench-toptestsarecurrentlyinDominionstaffreview.Inaddition,aconservativereducedscalesinglelooptesthasbeenperformedtodemonstratethattheNorthAnnaUnits1and2RecirculationSpray (RS)andLowHeadSafetyInjection(LHSI)pumpswillhaveanacceptablestrainerfaceheadlossduringlongtermcoolingfollowingaLOCA.Moreover,DominionandtheNRChaveconductedstatusupdateconferencecallsassociatedwithchemical effectstestingprogress,andthestaffhasreviewed SerialNo.08-0275 Docket Nos.50-338/339 Attachment 3Page2of13andcommentedonthetestingprotocolsforbench-top,singleloopandmulti-looptestingpreparedbyAtomicEnergyofCanada,Limited(AECL,thechemicaleffectstestingvendor).Furthermore,thestaffhaswitnessedcertainmulti-looptestingactivitiesatAECL'sChalkRiverTestFacility.Eventhoughconsiderableprogresshasbeenmadetoaddressthe rernammqGL2004-02correctiveactionsforNorthAnnaUnits1and2,certainchemicaleffectstestingactivitiescannotbecompletedbyMay31,2008.Specifically,completionofongoingreducedscalemulti-looptestingandevaluation,usingNorthAnnaspecificchemicalconditions,is requiredtoprovideconfidenceintheirapplicationto containmentsumpstrainerperformance.Subsequentreviewoftestresultsandfinalizationoftestdocumentationarealsorequiredtobecompletedoncetestinghasbeencompleted.Therefore,DominionisrequestingascheduleextensionforNorthAnnaUnits1and2tocompletetheremainingchemicaleffectstesting,technical evaluationsandreviews,andlicensingbasisupdates,aswellastodetermine whetheranyadditionalactionsmayberequiredbasedontheresultsofthetestingandtechnicalevaluations.Theinformationprovidedbelowincludesthebasisfortheextensionrequest.Specifically,Dominionhasaddressedthe"CriteriaforEvaluatingDelayofHardwareChanges,"asdescribedinSECY-()6-0078datedMarch31,2006.ThisdiscussionsupportsDominion'srequestforan extensionofthecorrectiveactionscompletiondatetoensurethatthenecessarytestinqandtechnicalevaluationshavebeencompletedandthesupportingcalculationsandtechnicalreportshavebeenreviewedandvalidatedtofacilitateresolutionofGSI-191issues.Anextensionisrequesteduntil September 30,2008tocompletetheremainingrequiredactionsandtoupdatetheassociatedlicensingbasisdocuments.TheproposedextensionforNorthAnnaUnits1and2doesnotaltertheoriginalconclusionssummarizedinGL2004-02inwhichthestaffdeterminedthatitisacceptableforPWRlicenseestooperateuntilthecorrectiveactionsarecompletedbecauseofsufficientlylowplantrisk.

2.0 Justification

for the Proposed ExtensionTheNRCprovidedajustificationforcontinuedoperation (JCD)inthe"SummaryofJuly26-27,2001MeetingwithNuclearEnergyInstituteandIndustryonECCS StrainerBlockageinPWRs,"datedAugust14,2001,thatsupportscontinuedoperationthrough December 31,2007.Elementsof thl3 JCDthatcontinuetobeapplicabletoNorthAnnaUnits1and2include:*BothNorthAnnaUnits1and2containmentsarecompartmentalized,thusslowing transportofdebristothesump.*Theprobabilityoftheinitiating event(i.e.,largebreakLDCA)isextremelylow.

Serial No.08-0275 Docket Nos.50-338/339 Attachment 3Page3of13*Leak-Before-Break(LBB)qualifiedpipingisof sufficient toughnessthatitwillmostlikelyleak(evenundersafe shutclownconditions)ratherthanrupture.*Thetimefor switchovertorecirculationfromthesumpafteraccidentinitiationallowsfordebrissettling.3.0CurrentStatusandReasonfortheProposedExtension3.1DownstreamEffects-FuelandReactorVessel WCAP-16793-NPRev.0,"EvaluationofLong-TermCoolingConsideringParticulate,FibrousandChemicalDebrisintheRecirculationFluid,"providesthe criteria forperformingdownstreameffectsevaluationsregardingcoreeffects.Thisevaluationhasbeencompletedandconcludedthat:

• Adequateflowtoremovedecay heatwillcontinuetoreachthecoreevenwithdebrisfromthesumpreachingtheReactorCoolantSystem(RCS)andcore,*Decayheatwillcontinuetoberemovedevenwithdebriscollectionatthefuel assembly spacer grids,*Fibrousdebris,shoulditenter the!coreregion,willnottightlyadheretothesurfaceoffuelcladding,*Simulatinglargedebrisloadingsoffiberglassandcalciumsilicate,decayheatwillberemoved,andacceptablefuelcladtemperatureswillbemaintained,and*Asblockageofthecorewillnotoccur,thecurrentacceptedlicensing calculations that demonstrateappropriateboricaciddilutiontoprecludeboricacidprecipitationremainvalid.

The plant-specificevaluationalsodemonstratedthatthe WCAP-16793-NPRev.0 conclusions are directlyapplicabletoNorthAnnaUnits1and2.

Consequently,thereisreasonableassurancethatforNorthAnnaUnits1and2,long-termcorecoolingwillbe establishedandmaintained post-LOCAevenwhenconsideringthepresenceofdebrisintheRCSandcore.RefertoNorthAnna'sSupplementalResponsetotheNRC,datedFebruary29,2008(SerialNumber OB-0019)paragraph3n,foramoredetailedtechnicaldiscussionoftheevaluation.Thiseffortiscomplete.Noextensionisrequiredforthis effort.3.2DownstreamEffects-ComponentWearandSystemPerformance WCAP-16406-PRev.1,"EvaluationofDownstreamSumpDebrisEffectsinSupportofResolutionofGSI-191,"providesrevisedguidancefortheperformanceof downstream effects evaluationsforcomponentwearandresultingsystem performance with potentiallydegradedcomponents.

Bevlssc downstream componentweareffectsand system performance evaluationshavebeencompletedforNorthAnnaUnits1and2by SerialNo.08-0275DocketNos.

50-338/339 Attachment 3Page4of13SargentandLundyandwereperformedinaccordancewiththe WCAP-16406-PRev.1guidelines.DominioniscurrentlyreviewingtheevaluationsandisscheduledtocompletethereviewbyJune18,2008.Theevaluationfindingsarepreliminaryatthistimeandaresummarizedasfollows:

3.2.1ComponentWearWearanalysisandweareffectsoncomponentperformancehavebeenperformedforthefollowingcomponents:*HighHeadSafetyInjection(HHSI)pumps(ChargingPumps),*LowHeadSafetyInjection(LHSI)pumps,*InsideRecirculationSpray(IRS)pumps,*OutsideRecirculationSpray(ORS)pumps,

• manuallythrottledvalves,*motoroperatedvalves,*orifices,*heatexchangers,and*piping.Theresultsofthecomponentwearevaluationdemonstratethatnon-pumpcomponentsareacceptableforwearandblockageinaccordancewith WCAP-16406-Pmethodologies,andORS,IRS,andSIpumpsmeettheacceptancecriteriaforperformanceandvibrationstartingfromtheirdesignclearances,whicharemonitoredandmaintainedbyDominion'sinservicetestingandcorrectivemaintenanceprograms.3.2.2SystemPerformanceThedownstreameffectsevaluationperformedforsystemperformance concluded theEmergencyCoreCoolingSystem(ECCS)andRSpumpsforNorthAnnaUnits1and2arecapableofsupplyingflowin exc:essoftheminimumsystemrequirements.Ithasbeendeterminedthatbothsystemsarecapableofmeetingtheminimumflowrequirementsunderdebrisladenconditionsforaperiodof30daysfollowingaLOCA.Inaddition,asystemvibrationevaluationhasdeterminedthattheRS,LHSIandHHSIpipingdoesnotexceedvibrationacceptancecriteria.MechanicalsealsintheECCSandRSsystemwillperformasdesiqned,anddebrisintherecirculatedsumpfluidwillnotadverselyaffecttheseals.TheRS,LHSI,andtwoofthesixHHSIpumpsareacceptableforvibration,astheirmaximumflowratesarewithinanalyzedrunoutlimits.FourofthesixHHSIpumpsarestillunderevaluation.

Serial No.08-0275 Docket Nos.50-338/339 Attachment 3Page5of13 3.3StrainerDebrisand cnemtcetEffectsTestingCompletionofchemicaleffectstestingandevaluationisrequiredtoconfirmthatthereplacementstrainersinstalledatNorthAnnaUnits1and2areadequatetomaintainNPSHmarginfortheECCSpumpsduringlong-termcorecoolingandtoconfirmthatnofurtherphysicalmodificationsarerequired.AchemicaleffectsevaluationiscurrentlybeingperformedforNorthAnnaUnits1and2byAECLtodeterminethepotentialforchemicalprecipitateformation.Publishedindustrydatawerecollected,consolidated,anddepictedasaseriesoftemperaturedependentcurvesplottedonapH/precipitateconcentrationgraph.Bench-toptestingwasperformedtoconfirmthe vallidityofthecurves,thusprovidinganaccurateindicationofwhenprecipitateformationwouldbeexpectedtooccur.Bench-toptestingiscomplete,andtheresultsarecurrentlyundergoinginternalDominionreview.Toverifytheresultsofthebench-toptestinpandevaluations,reducedscaletestingusingplant-specificchemicalconcentrationswasperformed.Single-loopreducedscaletestingwasperformedwithasimulationofexpectedSurrychemistryconditionsanddebrisload,astheSurryconditionsweredeterminedtobeboundingforNorthAnnaUnits1and2.ThetestresultsindicatethatNorthAnnaUnits1and2willsustainanacceptablestrainerfaceheadlossduetoathinbedformationfromlatentdebrisandchemicaleffects.Multi-looptestingisalsobeing emplloyedtoprovideameansofperformingnumerous(i.e.,six)reducedscaletestssimultaneously.NorthAnnaUnits1and2RSandLHSIstrainerswillbesimulatedwiththeNorthAnnaplantspecificfibrousandparticulatedebrisloadsandchemicalconditionsthatwouldbeexpectedtobeinthecontainmentsumpfollowingaLOCA.Eachtestwillbeperformedfor30daysfollowingtheformationofathindebrisbedataspecifiedtemperatureandflowratetoreproducethepossibilityofprecipitateformationanditsresultingimpactonheadloss.TestingiscurrentlyscheduledtobecompletedbyJuly 7,2008,andthefinalStrainerTestReportandthefinalChemicalStrainerHydraulicCalculationarescheduledtobeissuedbyAugust29,2008andSeptember12,2008.3.4ExtensionRequestDominionisrequestinganextensionuntilSeptember30,2008forcompletionofthefollowingactivities:*Internalreviewandissueoftinalanalysesandevaluationreportsofbench-toptesting,downstreamcomponentwearandsystemsperformance,anddebrisgenerationandtransport,*Chemicaleffectsreducedscaletesting,evaluation,andtestreportpreparationand

review, Serial No.08-0275 Docket Nos.50-338/339 Attachment 3Page6of13*Determinationofanyadditionalactionsthatmayberequiredbasedontheresultsofthechemicaleffectstestingandevaluations,and*Updateofdesignandlicensingbasisdocuments(e.g.,UFSAR,plantprocedures,etc.)toreflectplantchangesimplementedtoresolveGSI-191issues.

4.0 Compliance

withSECY-06-0078 Criteria SECY-06-0078specifiestwocriteriaforshortdurationGL2004-02 extensionslimitedtoseveralmonthsandathirdcriterionforextensionsbeyondseveralmonths.ThesethreecriteriaandtheassociatedresponsesforNorthAnnaUnits1and2areprovidedindetailbelow.

4.1 SECY-06-0078 Criterion No.1:Thelicenseehas a plant-specific technical/experimentalplanwith milestones andscheduletoaddress outstandingtechnicalissueswithenoughmarginto account for uncertainties.DominionResponse NORTH ANNAPLANTSPECIFIC TECHNICAL/EXPERIMENTAL PLANInaccordancewithNorthAnna'sPlantSpecificPlan,outlinedinDominion'sextensionrequestdatedNovember15, 2007',theGL2004-02supplementalresponsedatedFebruary29,2008andtheinformationdiscussedabove,thefollowingtaskshavebeencompleted(withoutstandingreviewsnotedwhereapplicable):*Debrisanalyses(currentlyinDominionreview) oDebrisgenerationanalysesinaccordancewith WCAP-16568-PRev0(ZoneofInfluencedetermination) oDebristransportanalysis*Downstreameffectsanalyses oFuelandvesseldownstreameffectsanalysesinaccordancewithNPRev.0 oDebrisblockage,componentwearandsystemperformancedownstreameffectsanalysesinaccordance withWCAP-16406-PRev.1(currentlyinDominion review)*Strainerheadlossandvortex testingforexpecteddebrisload(excludingchemical precipitants)*Bench-toptesting(includingconsiderationof WCAP-16530-NPresults)todeterminelikelyprecipitateformationandboundingquantitiesofprecipitantstouseinreducedscaletesting(currentlyinDominionreview)*ReplacementstrainerdesignandinstallationforbothNorthAnnaUnits1and2 Serial No.08-0275 Docket Nos.50-338/339 Attachment 3 Page7of13ReducedscalechemicaltestingandresultsevaluationoftheimpactofpotentialchemicalprecipitantsonstrainerheadlossarecurrentlyunderwayandarescheduledtobecompletedbySeptember12,2008.Tocompletethiseffortandadoptthelicensingbasisrequiredforlong-termcorecoolingrequiredforresolutionofGSI-191atNorthAnnaUnits1and2,thefollowingmilestoneshavebeenestablished:GL2004-02 CORRECTIVE ACTION MILESTONES Activity Milestone DateDownstreamwearcalculations,bench-toptesting,downstreamweareffectsoncomponents,andsystemperformance,anddebrisgenerationandtransport

• DominionreviewandcommentJune18,2008

• Issuefinalcalculations/evaluationsJuly18,2008PumpSeal Wear EvaluationsJuly31,2008SystemPerformanceEvaluationsJuly31,2008 Strainerchemicaleffectsreduced scaletestingandevaluation

• Completestrainerchemicaleffects July 7,2008 testing*AECLissueTestReportJuly31,2008

• DominionreviewandcommentAugust15,2008

• AECLissueFinalStrainerTestAugust29,2008 ReportDeterminationofwhetheranyhardware and/or proceduralmodificationsareSept.15,2008neededasaresultofthecompletionofthechemicalprecipitateheadlosstestinq SerialNo.08-0275 Docket Nos.50-338/339 Attachment 3Page8of13FieldChangetodesignchangepackage(DCP)to implementchemicaldesign documents*IssueFieldChangetostrainerinstallationDCPforacceptanceofSept.19,2008chemicalstrainertesting

• FacilitySafetyReviewCommitteeapprovalofdesignand licensingSept.30,2008basischangesBasedontheabovediscussion,NorthAnnaUnits1and2meettherequirementsofSECY-06-0078Criterion1.

4.2 SECY-06-0078 Criterion No.2: The licensee identifies mitigative measurestobe putinplace prior to December 31, 2007, and adequately describes how these mitigative measures will minimizetherisk of degraded EGGS[emergency core cooling system]functionsduringthe extension period.DominionResponseTodate,thefollowingmitigativemeasureshavebeenimplementedtominimizetheriskofdegradedECCSandRSsystemfunctionsduringtherequestedextensionperiod.AlthoughSECY-06-0078Criterion No.2specificallymentionsacompletiondateof December 31,2007,DominionwaspreviouslygrantedanextensionuntilMay31,2008tocompleteGL2004-02corrective actions(referenceNRCletterdatedDecember13,2007).Thefollowingmitigativemeasurespertaintothecurrentrequestforextensionto September30,2008: 4.2.1 Mitigative MeasuresDominionisfullycommittedtoresolvingtheissuesassociatedwithGSI-191andiscontinuingeffortstocompletethecorrectiveactionsasdetailedintheFebruary29,2008supplementalresponsetoGL2004-02.DominionhasimplementedthephysicalmodificationsidentifiedbelowatNorthAnnaUnits1and2.RefertotheNorthAnnaUnits1and2supplementalresponseforgreaterdetailontheinformationprovided below.

Serial No.08-0275DocketNos.

50-338/339 Attachment 3Page9of13 1.Physical Modifications As discussed in greaterdetailin Dominion's February 29, 2008 supplemental responsetoGL 2004-02, physical modifications include the installation of replacement strainersinUnits1and2.

Calcium-Silicate(Cal-Sit)and Microtherm insulation was either removed or replacedinUnits1and2 containments as requiredtoreducethe calculated quantities of particulatesandfiberthatcouldreachthe containment sumps and achieve the specified strainerheadlossandtohelpreduce component wear.Dominion has modifiedtheNorth AnnaUnits1and2 Refueling Water Storage Tanks (RWSTs)level instrumentationandtheSI automatic Recirculation Mode Transfer (RMT)setpoint toensuresufficient water is availabletomeetRSandLHSI strainer submergence requirements.

A 12-inchholewascoreboredinthe primary shieldwallplugforbothNorth AnnaUnits1and2to allow reactor cavity watertodrainfromthe in-coresump(ICS)roomintothe containmentsump.This facilitates transfer of additional watertothe containmentsumpto ensure full submergenceofthenew containment sump strainers.

2.Containment Cleanliness Dominion has proceduresinplaceto ensure containment cleanliness as documentedinthe responsetoNRCBulletin 2003-01,"Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized-Water Reactors." 3.Procedural Guidance.Training, and Actions Operators are trainedandhave guidance for monitoring ECCS pump parameters includinglossofNPSHas indicated by erratic pump current or discharge flow.4.I nformation Notice 2005-26 On September 16, 2005,theNRC issued Information Notice (IN)2005-26,"Results of ChemicalEffectsHeadLoss Testsina Simulated PWR Sump Pool Environment." IN 2005-26 appliestoplantswith calcium silicate insulation and trisodium phosphateasa buffer.Neither North AnnaUnitwaslistedinthis document as units having the above-described combinationinits containment; therefore, no responsetoIN 2005-26 was requiredforNorth AnnaUnit1or2.

SerialNo.08-0275 Docket Nos.50-338/339 Attachment 3Page10of135.RiskEvaluationWiththeinstallationofthenewcontainmentsumpstrainersandotherassociatedchangesandevaluations,there IhasbeenasignificantreductioninthevulnerabilitytodebrisblockageandcomponentwearintherecirculationsystemwhenmitigatingaLOCA.Fortheremainingoutstandingissueofchemicaleffects,thevulnerabilityislimitedtolargebreakLOCAsonly.ForsmallandintermediatebreakLOCAs,itisexpectedthattherewillbeasignificantreductionindebrisgeneration,asmuchasonetotwoordersofmaqnitude.Withthistypeofreductioninthefibrousandparticulatesources,corecoolinpwillbeassuredforsmallandintermediatebreakLOCAs.SincethenewstrainerwasdesignedtohandleaconservativelyestimatedquantityofthefibrousandparticulatedebrisloadingfromalargebreakLOCA,itisexpectedthatforparticulatedebrisloadingsthatareanorderofmagnitudeormorelower,therewillbeinsufficientparticulatetoformathin-bedonthereplacementstrainers,andtherewillpotentiallybeopenstrainerarea.Thus,itislikelythatanychemicalprecipitatesthataregeneratedwillnotcreateaheadlosslargerthanthetestedthin-bedheadloss,forwhichthestrainerwasdesigned,andadequateNPSHwillbemaintained.Furthermore,withanorderofmagnitudeormorereductionintheparticulatedebris,theparticulatedebrisconcentrationshouldbelowenoughsuchthatwearofdownstreamcomponentswouldbelimitedtothepointthatthereisreasonableassurancethattheECCSpumpsanddownstreamcomponentswouldcontinuetoprovideadequatecorecooling.Thus,thequantitativeriskevaluationaddressespotentialvulnerability'forlargebreakLOCAsonly.Theprobabilityofthisinitiatingeventislow(5.0E-6foroneyearor3.75E-6forninemonths)andtheprobabilityofalarge,earlyreleaseisnegligible.Dominion'spreviousextensionrequestdatedNovember15,2007,providedariskevaluationforanelevenmonthextension.TheNRCrepliedintheirresponseletterdatedDecember13,2007,withasummaryparagraphassociatedwiththerisk evaluation: "DominionprovidedariskevaluationforNorthAnna1andNorthAnna2,whichcomparedtheincreaseinCoreDamageFrequency(CDF)andLargeEarlyReleaseFrequencyfromalarge-breakLOCAtototalplantCDFandLERFriskvaluesandshowedthatthesevaluescouldbecategorizedas"small"inaccordancewith thocriteriastatedinRegulatoryGuide1.174,'AnApproachforUsingProbabilisticRiskAssessmentinRisk-InformedDecisionsonPlant-SpecificChangestotheLicensing Basis."Dominion'scurrentrequestforextensionisforninemonths,whichisenvelopedbytheelevenmonthriskassessmentreferencedabove.

SerialNo.08-0275DocketNos.

50-338/339 Attachment 3Page11of136.SafetyFeaturesandMarginsinCurrentConfiguration/DesignBasisDominionhasNRCapprovaltoinvoketheleak-before-break(LBB)methodologytoeliminatethedynamiceffects(pipewhipandjetimpingement)ofpostulatedprimarycoolantpipingrupturesfromthedesignbasisoftheplant.ForNorthAnnaUnits1and2,thelicensingbasisincludesapprovedLBBanalysisfortheRCSprimarylooppiping.Theapprovalwasbasedon theconclusionthattheprobabilityofapipefailurebeforenoticeableleakagecouldbedetectedandtheplantbroughttoasafeshutdownconditionissmall.Whileleak-before-breakisnotbeingusedtoestablishthedesignbasisdebrisloadonthesumpstrainers,itdoesprovideadditionalbasisforsafecontinuedoperationuntilthecompletionoftheGL2004-02corrective actions.7.Bench-topTesting

&ChemicalEvaluationsBench-toptestinghasbeencompleted,whichprovidesempiricalchemistrydatathatarespecifictoNorthAnna.

Thiisdata(currentlyinDominionreview)establisheswhatconditionsarerequiredfor NorthAnna'sexpectedcontainmentsumpchemicalmixtoeitherremaininsolutionorformprecipitates.Dominion'ssubsequentchemicalevaluations,basedonthesebench-topresults,haveconcludedthatNorthAnna'schemicalsareexpectedtoremaininsolution,supportingthepositionthatchemicaleffectsarenot expected!toincreasethesumpstrainerfaceheadloss.Basedontheabovediscussion,NorthAnnaUnits 1and2meettherequirementsofSECY-06-0078Criterion2.4.3SECY-06-0078 Criterion 3: For proposed extensions beyond several months, a licensee's request will more likely be accepted if the proposed mitigative measures include temporary physical improvementstotheEGGS sump or materials inside containment to better ensure a high level of EGGS performance.DominionResponseAsnotedabove,DominionhasimplementedthefollowingpermanentphysicalimprovementstothecontainmentsumptobetterensureahighlevelofECCSandRSsumpperformance.*StrainerInstallationDominioncompletedthe installatiionofreplacementstrainersystemsforbothunits.ThetotalsurfaceareaofthenewRSstrainersystemsareapproximately4400 fe(eachunit),andthetotalsurfaceareaoftheLHSIstrainerisapproximately2000 fe SerialNo.08-0275DocketNos.

50-338/339 Attachment 3Page12of13forUnit1,and1900 feforUnitThisreplacesthepreviousscreenswhichhadasurfaceareaofapproximately168 ft2foreachstrainer.*RSPumpStartTimeChangeTheRWSTinstrumentationwasmodifiedatbothNorthAnnaunitstochangethestartsignalsfortheRSpumps.Thischangewillensuresufficientwaterisavailabletomeetstrainersubmergencerequirements.A120-secondtimedelaywasaddedforthestartoftheIRSpumps,reducingtheloadimpactontheEmergencyDieselGeneratorsandallowingsufficienttimefortheORSpumpstofilltheirpipingandattainstableoperationpriorto thElstartoftheIRSpumps.*LHSIPumpRecirculationModeTransferChangeTheRWSTinstrumentationhasbeenmodifiedforbothunitstochangetheSafetyInjectionRMTsetpointtoallowmoreenergytoberemovedfromthe containment tolowerthesumpwatertemperaturepriortoswappingtheLHSIpumpsuctionfromtheRWSTtothecontainmentsump.ThischangealsoprovidesahigherwaterlevelinthecontainmentpriortoLHSIsuctionswaptothecontainmentsump.ThecombinationoflowertemperatureandhigherwaterlevelprovidesmoreNPSHtotheLHSIpumpsandprovidestherequiredvolumeofwatertomaintainstrainer submergence.*InsulationReplacement/RemovalatNAPSEvaluationswereperformedfor NorthAnnaUnits1and2toidentifylineswithinthecontainmentsthatrequiredinsulationremoval/replacementtominimizetheZoneofInfluence(ZOI)generatedparticulateduringacriticalpipebreak.Cal-SilandMicrotherminsulationwithintheZOIofpostulatedLOCApipebreakswasremoved/replacedduringtheNorthAnnaUnits1and22007RefuelingOutages(RFOs).RemovalofCal-SilandMicrotherminsulationwasrequiredtoachievethespecifiedstrainerheadlossandtohelpreducecomponentwear.*IncoreSumpRoomDrainAnICSroomdrainwasinstalledintheprimaryshieldwallplugforbothunitsduringthe2007RFOs.Thismodificationallowswaterheldupinthereactorcavitytodraintothecontainmentsumpfrom thoICSroomfacilitatingfullsubmergenceofthenewcontainmentsumpstrainers.Basedontheabovediscussion,NorthAnnaUnits1and2meettherequirementsof SECY-06-0078Criterion3.

Seria.lNo.

08-0275 Docket Nos.50-338/339 Attachment 3Page13of13 5.0 ConclusionAnextensionoftheNorthAnnaUnits1and2completiondatesfromMay31,2008toSeptember30,2008tocompletethecorrectiveactionsrequiredbyGL2004-02isacceptablebecause:*TheinitiatingeventandlargeearlyreleaseprobabilitiesforNorthAnnaUnits1and2associatedwithaninemonthextension(fromDecember 31,2007)are3.75E-6andnegligible,respectively.Thisriskimpactischaracterizedas"small"perNRCRegulatoryGuide1.174.*DominionhascompletedconsiderableworktofurtherpromoteahighlevelofEGGSandRSpumpperformanceincludingreplacementstrainerinstallationatbothNorthAnnaUnits1and2.*DominionhasimplementedmeasurestominimizetheriskofdegradedECCSandRSsystemfunctions (juringtheextensionperiod.*Dominionhascompletednumerouschemicalbench-toptests,performedaconservativereducedscaletest,andperformeddownstreamandchemicaleffects evaluationsinaccordancewiththeapplicableWGAPrequirementsthatprovidereasonableassurancethat:

oNPSHmarginwillbemaintainedintheeventofaLOCA, oDownstreamweareffectsareacceptable,and o Sufficientcorecoolingwillbemaintained.*Dominionhasaplant-specificplanwithmilestonesandschedulestoaddresstheoutstandingtechnicalissueswithsufficientconservatismtoaddressuncertainties.Therefore,perthecriteriaincludedinSEGY-06-0078,DominionhasestablishedthattheriskofdegradedECGSandRSfunctionsforNorthAnnaUnits1and2isnotconsidered significant.

Serial No.08-0275 Docket Nos.50-280/281 ACHMENT 4 NRC GENERIC LETTER 2004-02 POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATIONDURINGDESIGN BASIS ACCIDENTS AT PRESSURI:ZED-WATER REACTORS REQUESTFORANEXTENSIONOFTHE COMPLETION DATE FOR CORRECTIVE ACTIONS VIRGINIA ELEClrRICANDPOWER COMPANY (DOMINION)

SURRY POWE:R STATIONUNITS1AND2 SerialNo.08-0275 Docket Nos.50-280/281 Attachment 4Page1of13RequestforanExtensionoftheCompletionDatefor Corrective ActionsSurryPowerStationUnits1and21.0BackgroundDuringtheensuingworktocompletetheGL2004-02correctiveactions,itbecame apparentthatcertainactivitiesrequiredtoaddressthe containment sump issues couldnotbe completedbyDecember 31,:2007.Theseactivitiesincluded downstream effects evaluations for componentwearandsystem performanceandfor nuclearfuelandthereactorvessel,aswellaschemicaleffectstestingandevaluation.

Consequently,inaletterdated November15,2007(SerialNo.07-0660),Dominionrequestedan extension to November30,2008tocompletetheoutstandingcorrectiveactions.However,inaletterdatedDecember13,2007,theNRCtook exception to Dominion's extensionrequest.WhiletheNRCconfirmed 1thatadequatemitigation measureshadbeenputinplacetoreduceriskfortherequestedelevenmonth extension,thestaffalsonotedthat Dominion'srequestedextensiondatewasnotreasonablebasedonthecaseprovided.Duetothe importanceofpromptclosureofGL2004-02,theNRCgrantedDominionan extensiontoMay31,2008tocompletethe outstanding correctiveactionsforSurry Units 1and2.However,thestaffalsostatedthatshouldDominionbeunableto completetheSurryGL2004-02correctiveactionsbyMay31,2008, additional justificationmustbe providedtothe NRCforanyrequestedextensionbeyondthatdate.

As discussed in greaterdetailbelow,Dominionhasmade significantprogressregarding the completion of downstream effects evaluationsandchemicaleffectstestingand evaluation.

• DownstreamEffects-Downstreameffects evaluationshavebeen performed to determine:

1)theeffectofdebrisladenwateronthereactorvesselandfuel assemblies,and2)componentwearduetotheeffectsofdebrisandthe resultanteffect,ifany,onsystem performancedueto potentially degraded components.DetailsoftheevaluationresultsareprovidedinSections 3.1 and 3.2below.An extensionisrequiredtocompleteDominionstaffreviewofthe downstream componentwearandsystems performance evaluationsandtofinalizethe associated documentation.*ChemicalEffects-Bench-toptestinghasbeen completed to determine the solubility/precipitate behaviorofthechemicalsexpectedtoexistinthe containmentsumpasaresultofalossofcoolant accident(LOCA).Theresultsofthe bench-toptestsare currentlyinDominion staffreview.Inaddition,aSurry specific reducedscalesinglelooptestwasperformed(Seeitem 3.3below)to demonstratethattheSurryUnits 1and2RecirculationSpray(RS)andLowHeadSafetyInjection(LHSI)pumpswillhavean acceptablestrainerfaceheadlossduringlongtermcoolingfollowingaLOCA.Moreover,DominionandtheNRChave conductedstatusupdate conference calls associatedwithchemicaleffectstestingprogress,andthestaffhasreviewedand commented ontestingprotocolsfor bench-top,singleloopand SerialNo.08-0275 Docket Nos.50-280/281 Attachment 4Page2of13 multi-loop testingpreparedby AtomicEnergyof Canada,Limited(AECL,the chemical effectstestingvendor).Furthermore,the staff has witnessedcertain loop testing activities at AECL'sChalkRiverTestFacility.

Even though considerableprogresshasbeenmadeto address the remaining GL 2004-02 correctiveactionsforSurryUnits1and2,certain chemical effects testing activities cannotbecompleted by May 31,2008.Specifically, completion of ongoingreducedscale multi-looptestingand evaluation,usingSurry plant-specific chemical conditions,isrequiredtoprovide confidence in their application to containment sump strainer performance.

Subsequentreviewoftestresultsand finalizationoftest documentationarealsorequiredtobecompletedoncetestinghasbeen completed.

Therefore, Dominionisrequestinga schedule extensionforSurryUnits1and2to completetheremaining chemicaleffectstesting, technical evaluationsandreviews, and licensingbasisupdates,aswellasto determine whether any additional actionsmayberequiredbasedontheresultsofthetestingand technical evaluations.

The informationprovidedbelowincludesthebasisforthe extension request.Specifically, Dominion has addressedthe"Criteriafor EvaluatingDelayof Hardware Changes," as describedinSECY-()6-0078datedMarch31,2006.This discussion supports Dominion'srequestforanextensionofthe correctiveactionscompletion date to ensurethatthe necessarytestinqand technical evaluationshavebeen completedandthe supporting calculations and technicalreportshavebeenreviewedand validated to facilitate resolutionofGSI-191issues.An extensionisrequesteduntil September 30,2008to completetheremainingrequiredactions discussed belowandto update the licensing basis documents.TheproposedextensionforSurryUnits1and2doesnotalterthe original conclusions summarizedinGL 2004-02inwhichthe staff determinedthatitis acceptable for pressurized water reactor (PWR)licensees to operateuntilthe corrective actions are completed because of sufficientlylowplantrisk.

2.0 Justificationforthe

Proposed ExtensionTheNRC provided a justificationforcontinued operation(JCO)inthe"SummaryofJuly26-27,2001Meetingwith NuclearEnergyInstituteand IndustryonECCS Strainer BlockageinPWRs,"dated August14,2001,that supports continued operation through December 31,2007.ElementsoftheJCOthatcontinuetobe applicable to Surry Units1and2include:*BothSurryUnits1and2 containments are compartmentalized, thus slowing transportofdebristothesump.*The probabilityoftheinitiatingevent(i.e.,largebreakLOCA)is extremely low.*Leak-Before-Break(LBB)qualifiedpipingisof sufficient toughness thatitwillmostlikelyleak(even undersafeshutdown conditions)ratherthanrupture.

SerialNo.08-0275 Docket Nos.50-280/281 Attachment 4Page3of13*Surryisnotsusceptibletoprimarywaterstresscorrosioncrackingassociatedwith pressurizerAlloy600/82/182dissimilarmetalweldssincetheSurry pressurizer doesnotcontainthesetypesofwelds.*Thetimeforswitchovertorecirculationfromthesumpafteraccidentinitiationallowsfordebrissettling.

3.0 CurrentStatusandReasonfortheProposedExtension 3.1 DownstreamEffects-NuclearFueland Reactor Vessel WCAP-16793-NPRev.0,"EvaluationofLong-TermCoolingConsideringParticulate,FibrousandChemicalDebrisintheRecirculationFluid,"providesthecriteriaforperformingdownstreameffectsevaluationsregardingcoreeffects.Thisevaluationhasbeencompletedandconcludedthat:*AdequateflowtoremovedecayheatwillcontinuetoreachthecoreevenwithdebrisfromthesumpreachinqtheReactorCoolantSystem(RCS)andcore,*Decayheatwillcontinuetoberemovedevenwithdebriscollectionatthefuelassemblyspacergrids,*Fibrousdebris,shoulditenterthecoreregion,willnottightlyadheretothesurfaceoffuelcladding,*Simulatinglargedebrisloadingsoffiberglassandcalciumsilicate,decayheatwillberemoved,andacceptablefuelcladtemperatureswillbemaintained"and*Asblockageofthecorewillnotoccur,thecurrentacceptedlicensingcalculationsthatdemonstrateappropriateboricaciddilutiontoprecludeboricacidprecipitationremainvalid.

The plant-specificevaluationalsodemonstratesthatthe WCAP-16793-NPRev.0conclusionsaredirectlyapplicabletoSurryUnits1and2.Consequently,thereisreasonableassurancethatforSurryUnits1and2,long-termcorecoolingwillbe establishedandmaintainedpost-LOCAevenwhenconsideringthepresenceofdebrisintheRCSandcore.PleaserefertoSurry'sGL2004-02SupplementalResponsetotheNRC,datedFebruary29,2008(SerialNumber08-0018),paragraph3n,foramoredetailedtechnicaldiscussionoftheevaluation.Thiseffortiscomplete.Noextensionisrequiredforthiseffort.

3.2 DownstreamEffects-ComponentWearandSystem Performance WCAP-16406-PRev.1,"EvaluationofDownstreamSumpDebrisEffectsinSupportofResolutionofGSI-191,"providesrevisedguidancefortheperformanceofdownstream SerialNo.08-0275DocketNos.

50-280/281 Attachment 4Page4of13effectsevaluationsforcomponentwearandresultingsystemperformancewithpotentiallydegradedcomponents.ReviseddownstreamcomponentweareftectsandsystemperformanceevaluationshavebeencompletedforSurryUnits1and2bySargentandLundyandwereperformedinaccordancewiththe WCAP-16406-PRev.1guidelines.DominioniscurrentlyreviewingtheevaluationsandisscheduledtocompletethereviewbyJune18,2008.Althoughtheevaluationfindingsarepreliminaryatthistime,theyappeartobegenerallyfavorableandaresummarizedasfollows:3.2.1ComponentWearWearanalysisandweareffectsoncomponentperformancehavebeenperformedforthefollowingcomponents:*HighHeadSafetyInjection (HHSII)pumps(ChargingPumps),*OutsideRecirculationSpray(ORS)pumps,*InsideRecirculationSpray(IRS)pumps,*LowHeadSafetyInjection(LHSI)pumps,*manuallythrottledvalves,*motoroperatedvalves,*orifices,*cavitatingventuris,*recirculationspraynozzles,*heatexchangers,and*piping.Theresultsofthecomponentwearevaluationdemonstratethatnon-pumpcomponentsareacceptableforwearandblockageinaccordancewith WCAP-16406-Pmethodologies.Inaddition,theaiRS,IRS,andLHSIpumpsmeettheacceptancecriteriaforperformanceandvibrationstartingfromtheirdesignclearances,whicharemonitoredandmaintainedbyDominion'sinservicetestingandcorrectivemaintenanceprograms.However,theHHSIpumpsdonotmeetthecurrentgeneralacceptancecriteriaforvibration.Arotordynamicanalysisisbeingperformedtoascertainacceptancecriteriaspecifictothispumptype,andthe acceptabilityoftheHHSIpumps is currentlybeingre-evaluated.3.2.2SystemPerformanceThedownstreameffectsevaluationperformedforsystemperformance concluded theEmergencyCoreCoolingSystem(ECCS)andRSpumpsforSurryUnits1and2arecapableofsupplyingflowinexcessoftheminimumsystemrequirements.Under SerialNo.08-0275 Docket Nos.50-280/281 Attachment 4Page5of13maximumflow,theRSandLHSIpumpswillnotreachrunoutconditionunderdebrisladenconditionsfor 30daysfollowingaLOCA.TheLHSIpumpsmayexperienceflowratesthatcouldslightlyexceedthemaximumsafetyanalysisflowrate;however,theseflowrateswereanalyzedanddeterminedtobeacceptable,asadequatemarginremainedfornetpositivesuctionhead(NPSH).Also,asystemvibrationevaluationhasdeterminedthattheLHSIandRSpipingdonotexceedvibrationacceptancecriteria.MechanicalsealsintheECCSandRSsystemwillperformasdesigned,anddebrisintherecirculatedsumpfluidwillnotadverselyaffecttheseals.TheRS,LHSI,andoneofthesixHHSIpumpsareacceptableforvibration,astheirmaximumflowratesarewithinanalyzedrunoutlimits.ThefiveremainingHHSIpumpsarestillunderevaluation.

3.3 StrainerDebrisand

ChemicalEffectsTestingCompletionofchemicaleffectstestingandevaluationisrequiredtoconfirmthatthereplacementstrainersinstalledatSurryUnits1and2areadequatetomaintainNPSHmarginfortheECCSpumpsduringlong-termcorecoolingandtoconfirmthatnofurtherphysicalmodificationsarerequired.AchemicaleffectsevaluationiscurrentlybeingperformedforSurryUnits

'1and2byAECLtodeterminethepotentialforchemicalprecipitateformation.Publishedindustrydatawerecollected,consolidated,anddepictedasaseriesoftemperaturedependentcurvesplottedona pH/precipitatl3concentrationgraph.Bench-toptestingwasperformedtoconfirmthevalidityofthecurves,thusprovidinganaccurateindicationofwhenprecipitateformationwouldbeexpectedtooccur.Bench-toptesting is complete,andtheresultsarecurrentlyundergoinginternalDominionreview.Toverifytheresultsofthebench-toptestingandevaluations,reducedscaletestingusingplant-specificchemicalconcentrationswasperformed.Single-loopreducedscaletestingwasperformedwithasimulationofexpectedSurrychemistryconditionsanddebrisload.ThetestingresultsindicatethatSurryUnits1and2willsustainanacceptablestrainerfaceheadlossduetoathinbedformationfromlatentdebrisandchemicaleffects.Multi-looptestingisalsobeing empl'oyedtoprovideameansofperformingnumerous(i.e.,six)reducedscaletestssimultaneously.SurryUnits1and2RSandLHSIstrainerswillbesimulatedwiththeSurryplantspecificfibrousandparticulatedebrisloadsandchemicalconditionsthatwouldbeexpectedtobeinthecontainmentsumpfollowingaLOCA.Eachtestwillbeperformedfor 30daysfollowingtheformationofathindebrisbedataspecifiedtemperatureandflowratetoreproducethepossibilityofprecipitateformationanditsresultingimpactonheadloss.TestingiscurrentlyscheduledtobecompletedbyJuly 7, 2008,andthefinalStrainerTestReportandthefinalChemicalStrainerHydraulicCalculationarescheduledtobeissuedbyAugust29, 2008andSeptember 12, 2008, respectively.

SerialNo.08-0275 DocketNos.50-280/281 Attachment 4Page6of 13 3.4 Extension RequestDominionisrequestinganextensionuntilSeptember30,2008forcompletionofthefollowingactivities:*Internalreviewandissueoffinalanalysesandevaluationreportsofbench-toptesting,downstreamcomponentwearandsystemsperformance,anddebrisgenerationandtransport,*Chemicaleffectsreducedscaletesting,evaluation,andtestreportpreparationand review,*Determinationofanyadditionalactionsthatmayberequiredbasedontheresultsofthechemicaleffectstestingandevaluations,and*Updateofdesignandlicensingbasisdocuments(e.g.,UFSAR,TechSpecs,plantprocedures,etc.)toreflecttheplantchangesimplementedtoresolveGSI-191 issues.4.0 Compliance with SECY-06-0078 Criteria SECY-06-0078specifiestwocriteriaforshortdurationGL2004-02extensions,limitedtoseveralmonthsandathirdcriterionforextensionsbeyondseveralmonths.ThesethreecriteriaandtheassociatedresponsesforSurryUnits1and2areprovidedindetail below.4.1 SECY-06-0078 Criterion No.1:Thelicenseehas aplant-specifictechnical/experimentalplanwithmilestonesandscheduletoaddressoutstandingtechnicalissueswithenoughmarginto account for uncertainties.DominionResponseSURRYPLANTSPECIFIC TECHNICAL/EXPERIMENTAL PLAN In accordancewithSurry'sPlantSpecificPlan,outlinedinDominion'sExtensionRequestletterdatedNovember15,(SerialNo.07-0660),thefollowingtaskshavebeencompleted(withoutstandingreviewsnotedwhereapplicable):*Debrisanalyses(currentlyinDominionreview) oDebrisgenerationanalysesinaccordancewith WCAP-16568-PRev.0(ZoneofInfluencedetermination) o Debris transport analysis Serial No.08-0275 Docket Nos.50-280/281 Attachment 4Page7of13*Downstreameffectsanalyses oFuelandvesseldownstreameffectsanalysesinaccordancewithNPRev.O.oDebrisblockage,componentwearandsystem performance downstream effectsanalysesinaccordancewith WCAP-16406-PRev.1 (currentlyinDominion review)*Strainerheadlossandvortextestingforexpecteddebrisload(excludingchemical precipitants)*Bench-toptesting(includingconsiderationof WCAP-16530-NPresults)to determine likely precipitateformationandboundingquantitiesof precipitantstouseinreducedscaletesting (currentlyinDominionreview)

• Replacement strainerdesignforbothSurryUnits1and2,withcompletedinstallationforUnit1,andUnit2installationbeingcompletedduringtheongoingspring2008refuelingoutageReducedscalechemicaltestingandresultsevaluationoftheimpactofpotential chemical precipitantsonstrainerheadlossarecurrentlyunderwayandarescheduledtobecompletedby September12,2008.Tocompletethiseffortandadoptthelicensingbasisrequiredforlong-termcorecoolingrequiredforresolutionofGSI-191atSurryUnits1and2,thefollowingmilestoneshavebeenestablished:GL2004-02 ACTION MILESTONES Activity Milestone DateDownstreamwearcalculations,bench-top testing, downstreamweareffectson components,andsystemperformance,anddebrisgenerationandtransport

• DominionreviewandcommentJune18,2008

• Issuefinal calculations/evaluationsJuly18,2008PumpSeal Wear Evaluations July 31,2008 System Performance Evaluations July 31,2008 Strainerchemicaleffectsreducedscaletestingandevaluation

• Complete strainerchemicaleffects July 7,2008 testing SeriallNo.

08-0275 Docket Nos.50-280/281Attachment4Page8of13*AECLissueTestReportJuly31,2008

• DominionreviewandcommentAugust15,2008

• AECLissueFinalStrainerTestAugust29,2008 ReportDeterminationofwhetheranyhardware and/orproceduralmodificationsareSept.15,2008neededasaresultofthecompletionofthechemicalprecipitateheadlosstestingFieldChangetodesignchangepackage (DCP)to implementchemicaldesign documents*IssueFieldChangetostrainerinstallationDCPforacceptanceofSept.19,2008chemicalstrainertesting

• FacilitySafetyReviewCommitteeapprovalofdesignandlicensinqSept.30,2008basischanges License amendment request(LAH)to deleteRSsubsystems minimumrecirculationflowvaluefromtheSurryTechnicalSpecificationsSection 5.2.C*NRCapproveLAR submittedApril2,2008(SerialNo.

08**0168)Sept.30,2008todeleteRSflowdesignvaluethatisbeing revisedtoprovideadditionalpumpmarginBasedontheabovediscussion,SurryUnits1and2meettherequirementsof06-0078Criterion1.

4.2 SECY-06-0078 Criterion No.2: The licensee identifies mitigative meesurestobe putinplace prior to December 31, 2007, and adequately describes how these mitigative measures will minimizetherisk of degraded EGGS[emergency core cooling system]functions during the extension period.

Serial No.08-0275 Docket Nos.50-280/281 Attachment 4 Page9of13DominionResponseTodate,thefollowingmitigativemeasureshavebeenimplementedtominimizetheriskofdegradedECCSandRSsystemfunctionsduringtherequestedextensionperiod.AlthoughSECY-06-0078CriterionNo.2specificallymentionsacompletiondateofDecember31,2007,DominionwaspreviouslygrantedanextensionuntilMay31,2008tocompleteGL2004-02correctiveactions(referenceNRCletterdatedDecember13,2007).Thefollowingmitigativemeasurespertaintothecurrentrequestforextensionto September 30,2008:4.2.1MitigativeMeasuresDominionisfullycommittedtoresolvingtheissuesassociatedwithGSI-191andiscontinuingeffortstocompletethecorrectiveactionsasdetailedintheFebruary29,2008supplementalresponsetoGL2004-02.DominionhasimplementedthephysicalmodificationsidentifiedbelowatSurryUnits1and2.RefertotheSurryUnits1and2supplementalresponseforgreaterdetailontheinformationprovidedbelow.1.PhysicalModificationsAsdiscussedintheFebruary2008supplementalresponsetoGL2004-02,DominioncompletedtheinstallationofreplacementstrainersystemsinUnit1andiscurrentlycompletingtheUnit2strainerinstallationduringtheongoingspring2008refuelingoutage.Dominionhasrepaired,jacketed,orremoveddamagedorunqualifiedinsulationandinsulationjacketinginSurry Uniit1containment,andiscurrentlyperformingthesamemodificationsintheSurryUnit2containmentduringtheongoingrefuelingoutage,asrequiredtoreducecalculatedquantitiesoffiberthatcouldreachthe containmentsumpsandachievethespecifiedstrainerheadlossandhelpreducecomponentwear.DominionhasmodifiedtheSurryUnits1and2RefuelingWaterStorageTanks(RWSTs)levelinstrumentationtoensuresufficientwaterisavailabletomeetRSandLHSIstrainersubmergencerequirements.A12-inchholewascoreboredintheprimaryshieldwallplugforbothSurryUnits1and2toallowreactorcavitywatertodrainfromthein-coresump(ICS)roomintothecontainmentsump.Thisfacilitatestransferofadditionalwatertothecontainmentsumptoensurefullsubmergenceofthenewcontainmentsumpstrainers.

Seria.l No.08-0275DocketNos.

50-280/281 Attachment 4Page10of132.ContainmentCleanlinessDominionhasproceduresinplacetoensurecontainmentcleanlinessasdocumentedintheresponsetoNRCBulletin2003-01,"PotentialImpactofDebrisBlockageonEmergencySumpRecirculationatPressurized-WaterReactors."3.ProceduralGuidance.Training,andActionsOperatorsaretrainedandhaveguidanceformonitoringECCSpumpparametersincludinglossofNPSHasindicatedbyerraticpumpcurrentordischargeflow.4.InformationNotice2005-26OnSeptember16,2005,theNRCissuedInformationNotice(IN)2005-26,"ResultsofChemicalEffectsHeadLossTestsinaSimulatedPWRSumpPoolEnvironment."IN2005-26appliestoplantswithcalciumsilicateinsulationandtrisodiumphosphateasabuffer.NeitherSurryunitwaslistedinthisdocumentasunitshavingtheabove-describedcombination initscontainment;therefore,noresponsetoIN2005-26wasrequiredforSurryUnit1or2.5.RiskEvaluationWiththeinstallationofthenewcontainmentsumpstrainersandotherassociatedchangesandevaluations,therehasbeenasignificantreductioninthevulnerabilitytodebrisblockageandcomponentwearintherecirculationsystemwhenmitigatingaLOCA.Fortheremainingoutstandingissueofchemicaleffects,thevulnerabilityislimitedtolargebreakLOCAsonly.ForsmallandintermediatebreakLOCAs,itisexpectedthattherewillbeasignificantreductionindebrisgeneration,asmuchasonetotwoordersof rnaqnitude.Withthistypeofreductioninthefibrousandparticulatesources,corecoolingwillbeassuredforsmallandintermediatebreakLOCAs.SincethenewstrainersweredesignedtohandleaconservativelyestimatedquantityofthefibrousandparticulatedebrisloadingfromalargebreakLOCA,itisexpectedthatforparticulatedebrisloadingsthatareanorderofmagnitudeormorelower,therewillbeinsufficientparticulatetoformathin-bedonthereplacementstrainers,andtherewillpotentiallybeopenstrainerarea.Thus,itislikelythatanychemicalprecipitatesthataregeneratedwillnotcreateaheadlosslargerthanthetestedthin-bedheadloss,forwhichthestrainerwasdesigned,andadequateNPSHwillbe maintained.Furthermore,withanorderofmagnitudeormorereductionintheparticulatedebris,theparticulatedebrisconcentrationshouldbelowenoughsuchthatwear o'fdownstreamcomponentswouldbelimitedtothepointthatthereisreasonableassurancethattheECCSpumpsanddownstreamcomponentswouldcontinuetoprovideadequatecorecooling.Thus,thequantitativeriskevaluationaddressespotentialvulnerabilityforlargebreakLOCAsonly.Theprobabilityofthisinitiatingeventislow(5.0E-6foroneyearor3.75E-6forninemonths)andtheprobability ofalarge,earlyreleaseisnegligible.

SerialNo.08-0275 Docket Nos.50-280/281 Attachment4Paqe11of13 Dominion'spreviousextensionrequestdated November15,2007,providedariskevaluationforanelevenmonthextension.TheNRCrepliedintheir response letter dated December13,2007,withasummaryparagraph associatedwiththerisk evaluation: "DominionprovidedariskevaluationforSurry1andSurry2,whichcomparedtheincreaseinCoreDamageFrequency(CDF)andLargeEarlyReleaseFrequency(LERF)fromalarge-breakLOCAtototalplantCDFandLERFriskvaluesandshowedthatthesevaluescouldbecategorizedas"small"in accordancewiththecriteriastatedinRegulatoryGuide1.174,'An ApproachforUsingProbabilisticRisk AssessmentinRisk-InformedDecisions on Plant-SpecificChangestotheLicensingBasis.

'" Dominion'scurrentrequestforextensionisforninemonths,whichisenvelopedbytheelevenmonthrisk assessmentreferencedabove.6.SafetyFeaturesand Marginsin Current Configuration/Design BasisDominionhasNRCapprovaltoinvokethe leak-before-break (LBB)methodology to eliminate the dynamiceffects(pipewhipandjet impingement)ofpostulatedprimarycoolantpipingrupturesfromthedesignbasisoftheplant.ForSurryUnits1and2,thelicensingbasisincludesapprovedLBBanalysisfortheRCSprimaryloop,the pressurizersurgeline,andportionsofthe Feedwater andMainSteamlines.Theapprovalwasbasedon thHconclusionthatthe probabilityofapipefailurebeforenoticeableleakagecouldbedetectedandtheplantbroughttoasafeshutdownconditionissmall.While leak-before-breakisnotbeingusedtoestablishthedesignbasisdebrisloadonthesumpstrainers,itdoesprovide additional basisforsafecontinuedoperation untilthecompletionoftheGL2004-02corrective actions.7.Bench-TopTesting

&ChemicalEvaluationsBench-toptestinghasbeencompleted,whichprovidesempirical chemistrydatathat are specifictoSurry.This data(currentlyinDominionreview) establishes whatconditionsarerequiredforSurry'sexpected containmentsumpchemicalmixto eitherremaininsolutionorformprecipitates.Dominion's subsequent chemicalevaluations,basedonthesebench-topresults,haveconcludedthatSurry'schemicalsareexpectedtoremaininsolution,thussupportingthepositionthatchemicaleffectsarenotexpectedtoincreasethesumpstrainerfaceheadloss.Basedontheabovediscussion,SurryUnits1and2meetthe requirements of SECY-06-0078Criterion2.

SerialNo.08-0275DocketNos.50-280/281 Attachment 4 Page 12 of 13 4.3 SECY-06-0078Criterion3:

For proposedextensionsbeyondseveralmonths, alicensee'srequest willmorelikelybeacceptediftheproposedmitigativemeasuresincludetemporaryphysicalimprovementstothe EGGSsumpormaterialsinsidecontainmenttobetterensure ahighlevelof EGGS performance.

Dominion ResponseAsnotedabove,Dominionhas implementedoris currently implementing, the following permanent physical improvementstothe containmentsumpto better ensureahighlevelofECCSandRSsump performance.

• Strainer Installation Dominion completed the installation of replacement strainer systemsforUnit1,and will completeUnit2duringthe currentspring2008refuelingoutage.Thetotal surfaceareaofthenewRS strainersystemsis approximately 6220 ft2forUnit1and6258ft 2forUnit2,andthetotalsurfaceareaoftheLHSI strainer is approximately2180ft 2forUnit1and2230ft 2torUnit2.This replaces the previous screens, whichhadatotalsurfaceareaof approximately 158 ft2foreachstrainer.*RSPump StartTimeChangeTheRWST instrumentationwasmodifiedonbothSurryunitstochangethestart signalsfortheRSpumps.Thischangewillensure sufficient water is available to meet strainer submergencerequirements.A 120-second time delaywasaddedforthestartoftheORSpumps, minimizing the impactonthe Emergency Diesel Generators,andallowing sufficienttimefortheIRSpumpstofillitspipingandattain stable operationpriortothestartoftheORSpumps.

• InsulationRemovalor.Jacketlnq/ltepalratSurry Containment insulationthatwas damagedorhad unqualified jacketingwasrepaired,removed,or jacketedwithaqualified jacketingsystemin SurryUnit1,andthesame modifications are currently implementedinSurryUnit2.Thiswill further minimize the amountofsprayand submergence generateddebrisatSurry.*IncoreSump(ICS)RoomDrainAnICSroomdrainwas installedintheprimaryshieldwallplugon SurryUnit2duringthefall2006RFOandonUnit1duringthefall2007RFO.This modification allows waterheldupinthereactorcavitytodraintothe containmentsumpfromtheICSroom, facilitating full submergenceofthenew containment sump strainers.

Serial No.08-0275 Docket Nos.50-280/281 Attachment 4 Page13of13Basedontheabovediscussion,SurryUnits1and2meettherequirementsof06-0078Criterion3.5.0ConclusionAnextensionoftheSurryUnits1and2completiondatesfromMay31,2008toSeptember30,2008tocompletethecorrectiveactionsrequiredbyGL2004-02isacceptablebecause:*Theinitiatingeventandlarge,earlyreleaseprobabilitiesforSurryUnits1and2associatedwiththeninemonthextension(fromDecember31,2007)are3.75E-6andnegligible,respectively.Thisriskimpactischaracterizedas"smaill"perNRCRegulatoryGuide1.174.*DominionhascompletedconsiderableworktofurtherpromoteahighlevelofEGGSandRSpumpperformanceincludingreplacementstrainerinstallationonSurryUnit1.Unit2strainerinstallationisbeingcompletedduringtheongoingspring2008refuelingoutage.*DominionhasimplementedmeasurestominimizetheriskotdegradedEGCSandRSfunctionsduringtheextensionperiod.*Dominionhascompletednumerouschemicalbench-toptests,performedaSurryplantspecificreducedscaletest,andperformeddownstreamandchemicaleffects evaluationsinaccordancewiththeapplicableWGAPrequirements that providereasonableassurancethat:

oNPSHmarginwillbe maintainedintheeventofaLOGA, oDownstreamweareffectsareacceptable,and o Sufficientcorecoolingwillbemaintained.*Dominionhasaplant-specificplanwithmilestonesandschedulestoaddresstheoutstandingtechnicalissueswithsufficientconservatismtoaddressuncertainties.Therefore,perthecriteriaincludedinSEGY-06-0078,DominionhasestablishedthattheriskofdegradedEGCSandRS functionsforbothSurryUnits1and2isnotconsidered significant.

o