RS-12-168, Co., LLCs 180-day Response to NRC Request for Information Pursuant to 10CFR50.54(f) Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident

Co., LLCs 180-day Response to NRC Request for Information Pursuant to 10CFR50.54(f) Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident

ML12332A305
Person / Time
Site:	Dresden
Issue date:	11/27/2012
From:	Kaegi G Exelon Generation Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
RS-12-168
Download: ML12332A305 (53)

Text

10 CFR 50.54(f)

RS-12-168 November 27, 2012 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, MD 20852 Dresden Nuclear Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket Nos. 50-237 and 50-249

Subject:

Exelon Generation Company, LLCs 180-day Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident

References:

1. NRC Letter, Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated March 12, 2012

2. NRC Letter, Endorsement of Nuclear Energy Institute (NEI) 12-07, Guidelines For Performing Verification Walkdowns of Plant Flood Protection Features, dated May 31, 2012

3. Exelon Generation Company, LLCs 90-day Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendations 2.1 and 2.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident (Flooding), dated June 11, 2012 On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued Reference 1 to all power reactor licensees. Enclosure 4 of Reference 1 contains specific Requested Actions, Requested Information, and Required Responses associated with Recommendation 2.3 for Flooding. On June 11, 2012, Exelon Generation Company, LLC (EGC) submitted the 90-day response requested in Enclosure 4 of Reference 1, confirming that EGC would use the NRC-endorsed flooding walkdown procedure (Reference 3).

U.S. Nuclear Regulatory Commission 180-Day Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding November 27, 2012 Page 2 For flooding Recommendation 2.3 (walkdowns), Enclosure 4 of Reference 1 states that within 180 days of the NRC's endorsement of the walkdown process (Reference 2), each addressee will submit a final response, including a list of any areas that are unable to be inspected due to inaccessibility and a schedule for when the walkdown will be completed. This letter provides the Dresden Station, Units 2 and 3 180-day response to Reference 1 for Flooding Recommendation 2.3.

Conditions identified during the walkdowns were documented and entered into the corrective action program. Performance of the walkdowns provided confirmation, with two exceptions, that flood protection features are in place, are in good condition and will perform as credited in the current licensing basis. The two deficiencies will be restored to their original design for resolution of the issues. to this letter provides the requested information for Dresden Station Units 2 and 3.

This letter contains no new regulatory commitments.

Should you have any questions concerning the content of this letter, please contact Ron Gaston at (630) 657-3359.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 27th day of November 2012.

Respectfully, 0

Glen T. Kaegi Director - Licensing & Regulatory Affairs Exelon Generation Company, LLC

Enclosures:

1.

Flooding Walkdown Report In Response To The 50.54(f) Information Request Regarding Near-Term Task Force Recommendation 2.3: Flooding for the Dresden Nuclear Power Station, Units 2 and 3 cc:

Director, Office of Nuclear Reactor Regulation Regional Administrator - NRC Region III NRC Senior Resident Inspector - Dresden Units 2 and 3 NRC Project Manager, NRR - Dresden Units 2 and 3 Illinois Emergency Management Agency - Division of Nuclear Safety U.S. Nuclear Regulatory Commission 180-Day Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding November 27,2012 Page 2 For flooding Recommendation 2.3 (walkdowns), Enclosure 4 of Reference 1 states that within 180 days of the NRC's endorsement of the walkdown process (Reference 2), each addressee will submit a final response, including a list of any areas that are unable to be inspected due to inaccessibility and a schedule for when the walkdown will be completed. This letter provides the Dresden Station, Units 2 and 3 180-day response to Reference 1 for Flooding Recommendation 2.3.

Conditions identified during the walkdowns were documented and entered into the corrective action program. Performance of the walkdowns provided confirmation, with two exceptions, that flood protection features are in place, are in good condition and will perform as credited in the current licensing basis. The two deficiencies will be restored to their original design for resolution of the issues. to this letter provides the requested information for Dresden Station Units 2 and 3.

This letter contains no new regulatory commitments.

Should you have any questions concerning the content of this letter, please contact Ron Gaston at (630) 657-3359.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 27th day of November 2012.

Respectfully,

.hL7J~O Glen T. Kaegi Director - Licensing & Regulatory Affairs Exelon Generation Company, LLC

Enclosures:

1. Flooding Walkdown Report In Response To The 50.54(f) Information Request Regarding Near-Term Task Force Recommendation 2.3: Flooding for the Dresden Nuclear Power Station, Units 2 and 3 cc:

Director, Office of Nuclear Reactor Regulation Regional Administrator - NRC Region III NRC Senior Resident Inspector - Dresden Units 2 and 3 NRC Project Manager, NRR - Dresden Units 2 and 3 Illinois Emergency Management Agency - Division of Nuclear Safety

U.S. Nuclear Regulatory Commission 180-Day Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding November 27, 2012 Page 3 Flooding Walkdown Report In Response To The 50.54(f) Information Request Regarding Near-Term Task Force Recommendation 2.3: Flooding for the Dresden Station, Units 2 and 3 (50 pages)

Joseph V. Bellini AMEC/Exelon 11/20/12 FLOODING WALKDOWN REPORT IN RESPONSE TO THE 50.54(f) INFORMATION REQUEST REGARDING NEAR-TERM TASK FORCE RECOMMENDATION 2.3: FLOODING for the DRESDEN NUCLEAR POWER STATION (UNIT 2 & UNIT 3) 6500 North Dresden Road, Morris, IL 60450 Renewed Facility Operating License Nos. DPR-19 & DPR-25 NRC Docket Nos. 50-237 & 50-249 Exelon Generation Company, LLC 300 Exelon Way, Kennett Square, PA 19348 Prepared by:

AMEC Environment & Infrastructure, Inc.

502 West Germantown Pike, Suite 850, Plymouth Meeting, PA 19462 November 20, 2012 Printed Name Affiliation Signature Preparer:

PETR MASOPUST AMEC Reviewer:

MATIHEW LEHRER AMEC Approver:

JEFFREY WRIGHT AMEC Lead Responsible Engineer:

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Branch Manager:

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Corporate Acceptance:

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NTTFRecommendation2.3(Walkdowns):Flooding ExelonCorporation November20,2012 Revision0

Contents 1.

EXECUTIVE

SUMMARY

...............................................................................................................................2 2.

PURPOSE....................................................................................................................................................3 a.

Background............................................................................................................................................3 b.

SiteDescription......................................................................................................................................4 c.

RequestedActions.................................................................................................................................6 d.

RequestedInformation..........................................................................................................................6 3.

METHODOLOGY.........................................................................................................................................7 a.

OverviewofNEI1207(WalkdownGuidance)......................................................................................7 b.

ApplicationofNEI1207........................................................................................................................8 c.

ReasonableSimulations.........................................................................................................................9 d.

WalkdownInspectionGuidance..........................................................................................................12 4.

RESULTS...................................................................................................................................................12 a.

RequestedInformationItem2(a)-DesignBasisFloodHazards.........................................................12 b.

RequestedInformationItem2(b)-CLBProtectionandMitigationFeatures.....................................17 c.

RequestedInformationItem2(c)-FloodWarningSystems...............................................................18 d.

RequestedInformationItem2(d)-FloodProtectionSystem/BarrierEffectiveness..........................19 e.

RequestedInformationItem2(e)-ImplementationofWalkdownProcess.......................................36 f.

RequestedInformationItem2(f)-FindingsandCorrectiveActionsTaken/Planned.........................38 g.

RequestedInformationItem2(g)-Cliff-EdgeEffectsandAvailablePhysicalMargin.......................41 h.

RequestedInformationItem2(h)-Planned/NewlyInstalledFloodProtectionEnhancements........41 5.

CONCLUSIONS..........................................................................................................................................42 6.

REFERENCES.............................................................................................................................................48

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1. EXECUTIVE

SUMMARY

Per NRCs request, a flooding protection walkdown was conducted at Dresden Nuclear Power Station (DresdenStation)toidentifyandaddressplantspecificdegraded,nonconforming,orunanalyzedconditions of plants flood protection features, including flood mitigation procedures. The flooding walkdown was conducted between August 8 and August 16, 2012 and included visual inspections and reasonable simulations.

Thescopeofthefloodingwalkdownwasdevelopedfollowingadetailedreviewofallrelevantlicensing documents.SincethesiteisinundatedduringthedesignbasisPMFevent,DresdenStationislicensedto mitigateagainsttheaffectsofafloodbyimplementingprocedurestopreventdamagetothereactorcore.

The main flood emergency procedure (DOA 001004) invokes several standard operating procedures to provideforsafeshutdownandcooldownofbothreactors.Therefore,thefloodemergencyprocedures along with associated standard operating procedures were the main focus of the walkdown. Dresden Stationdoesnothaveincorporated/exteriorortemporaryfeaturesthatarecreditedinthecurrentlicensing basis(CLB)documentswithprovidingfloodprotection.However,belowgradestructures(i.e.,basement walls and basement slabs) of Unit 2 and 3 Reactor and Turbine Buildings were designed to withstand hydrostaticloadsassociatedwithextremegroundwaterconditionsandwerevisuallyinspectedaspartof thefloodingwalkdown.

Themethodologyandacceptancecriteriafortheevaluationoffloodprotectionfeatureswasdeveloped basedonNEIreport1207(Rev0A),GuidelinesforPerformingVerificationWalkdownsofPlantProtection Features.Theverificationprocessforallimplementingproceduresincludedareasonablesimulation(i.e.,a detailed procedure walkthrough with the staff responsible for implementation of the procedure). For proceduresorproceduralstepsthathavenotbeenperformedinthepast,adrillorexercisewasperformed as part of the reasonable simulation to verify that the procedure can be performed as specified. Since standard operating shutdown procedures are an integral part of the of the flood mitigation strategy at DresdenStation,theseprocedureswerealsoreviewedtoverifythattheycanbeimplementedduringa floodemergencyandwillnotbechallengedbyfloodingconditions.

VisualinspectionsofbelowgradewallsofUnit2and3ReactorandTurbineBuildingswereconductedto verifytherearenopotentialobservablestructuraldeficienciesthatmayimpactthestructuresabilityto withstandhydrostaticloads.Inaddition,penetrationsealswerealsovisuallyinspectedanddocumentedas acomponentofthewallfeatures.Therewerefifteen(15)areaswithbelowgradewallsandslabs,which werevisuallyinspectedduringthewalkdown.Allofthewallsandslabswereaccessible;however,three penetrationswereconsideredinaccessible,duetoapipeconfigurationorapullboxpreventingaccessto thepenetration.SincethepenetrationsarenotcreditedasindividualfloodprotectionfeaturesintheCLB, reviewofavailabledrawingsandengineeringjudgmentwereusedtoassesswhethertheycouldpotentially impacttheabilityofbelowgradewallstofunctionasafloodbarrier.Therewasnoevidenceofleakage belowtheseinaccessiblepenetrations.

Electricalconduitsenteringthereactorbuildingwereevaluatedtodeterminewhethertheycanprovidea pathway for groundwater into safetyrelated buildings. In general, electrical conduits routed to safety relatedbuildingsareequippedwithcouplingsandplugsonbothendstopreventgroundwaterintrusion.At oneinstance,twoelectricalconduitswereroutedthroughapenetrationsleevewithaninternalseal,which was inaccessible for visual inspection during the walkdown; however, a reasonable assurance that the conditionoftheconduitisacceptablewasprovided.Noneoftheelectricalconduitsenteringthesafety relatedareasoftheplantareroutedthroughelectricalmanholes.

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Thefloodemergencyprocedureandtheassociatedprocedures(includingstandardshutdownprocedures) werereasonablysimulatedtoensurethattheycanbeperformedasspecifiedandprotectthereactorfrom core damage during flooding conditions. Overall, nineteen (19) reasonable simulations related to the implementationofthefloodemergencyprocedurewereperformed.Basedontheresultsoftheevaluation and the review of operator logs, the critical path items of the flood emergency procedure can be implementedaswrittenifsufficientfloodwarningavailable.Duringtheevaluationitwasdeterminedthat resourcesarenotavailabletoaccuratelypredictriverlevelsattheDresdenintakeinadvance.However,itis reasonabletoassumethatalimitedfloodwarningwouldbeobtainedfromDresdenLockMasterorusing riverforecastingtoolsfortheIllinoisRiverwatershed.Inaddition,thefloodemergencyprocedureisalso enteredfollowinganotificationfromTransmissionSystemOperatorpredictingrainfallof2inchesin6 hours.Thisallowsthesitetoinitiatefloodprotectionmeasuresbasedonarainfallforecastand/orlimited flood warning. Assuming that only a short flood warning is available, the construction of the Isolation CondenserMakeupPumphousesandbagmaynotbeimplementedintimeusingtheavailableresources.

However,initiationofsandbaggingpreparationsatanearlierpointinthefloodemergencyproceduredue toweatherforecastwillaidtheStationintimelyconstructionofthesandbagbermandprovideadditional marginofsafety.

2. PURPOSE

a. Background InresponsetothenuclearfueldamageattheFukushimaDaiichipowerplantduetotheMarch11,2011 earthquakeandsubsequenttsunami,theUnitedStatesNuclearRegulatoryCommission(NRC)established theNearTermTaskForce(NTTF)toconductasystematicreviewofNRCprocessesandregulations,andto make recommendations to the Commission for its policy direction. The NTTF reported a set of recommendationsthatwereintendedtoclarifyandstrengthentheregulatoryframeworkforprotection againstnaturalphenomena.

OnMarch12,2012,theNRCissuedaninformationrequestpursuanttoTitle10oftheCodeofFederal Regulations,Section50.54(f)(10CFR50.54(f)or50.54(f))(Reference3)whichincludedsix(6)enclosures:

[NTTF]Recommendation2.1:Seismic

[NTTF]Recommendation2.1:Flooding

[NTTF]Recommendation2.3:Seismic

[NTTF]Recommendation2.3:Flooding

[NTTF]Recommendation9.3:EP LicenseesandHoldersofConstructionPermits InEnclosure4ofReference3,theNRCrequestedthatlicenseesperformfloodprotectionwalkdownsto identify and address plantspecific degraded, nonconforming, or unanalyzed conditions and cliffedge effects(throughthecorrectiveactionprogram)andverifytheadequacyofmonitoringandmaintenance procedures(seenoteregardingcliffedgeeffects).

Structures,systems,andcomponents(SSCs)importanttosafetyatnuclearpowerplantsmustbedesigned towithstandtheeffectsofnaturalphenomena,includingfloods,withoutlossofcapabilitytoperformtheir Page3

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intended safety functions. For flooding walkdowns, identifying/addressing plantspecific degraded, nonconforming, or unanalyzed conditions (through the corrective action program) and verifying the adequacyofmonitoringandmaintenanceproceduresisassociatedwithfloodprotectionandmitigation featurescreditedinthecurrentdesign/licensingbasis.Newfloodhazardinformationwillbeconsideredin responsetoEnclosure2ofReference3.

OnbehalfofExelonGenerationCompany,LLC(Exelon),thisreportprovidestheinformationrequestedin theMarch12,201250.54(f)letter;specifically,theinformationlistedundertheRequestedInformation sectionofEnclosure4,paragraph2(athroughh).TheRequestedInformationsectionofEnclosure4, paragraph1(athroughj),regardingfloodingwalkdownprocedures,wasaddressedviaExelonsJune 11,2012,acceptance(Reference1)oftheindustrywalkdownguidance(Reference2).

NoteRegardingCliffEdgeEffects Cliffedge effects were defined by the NTTF Report (Reference 5), which noted that the safety consequencesofafloodingeventmayincreasesharplywithasmallincreaseinthefloodinglevel.While theNRCusedthesametermastheNTTFReportintheMarch1250.54(f)informationrequest(Reference 3), the information the NRC expects utilities to obtain during the Recommendation 2.3: Flooding Walkdowns is different. To clarify, the NRC is now differentiating between cliffedge effects (which are dealt with under Enclosure 2 of Reference 3) and a new term, Available Physical Margin (APM). APM informationwillbecollectedduringthewalkdowns,butwillnotbereportedintheresponsetoEnclosure4 of Reference 3. The collected APM information will be available for use in developing the response to ofReference3.

b. Site Description DresdenStationislocatedapproximately8mileseastofMorris,Illinois.Theplantislocatedattheconfluence oftheKankakee,DesPlaines,andIllinoisrivers,whicharethemajorfloodingsourcesconsideredintheCLB.

ThecontributingdrainageareatotheKankakeeRiverupstreamoftheintakeisapproximately5,165square miles, and the contributing drainage area to the Des Plaines River upstream of the confluence is approximately2,111squaremiles.

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DresdenNuclearPower Station

Figure1:SiteLocation

Theplantissituateddirectlyadjacenttotheriver,withadesignplantgradeelevationof517.0feetMean SeaLevel(MSL).AlloftheelevationsreferencedintheDresdenLicensingdocumentsarebasedonaMSL Datum. The lowest subgrade floor containing equipment important to safety are service water pumps motorsintheintakestructure,whicharesetonafloorelevation509.0ftMSLandareunprotectedfrom floodingabovethiselevation(Reference10).Nonwatertightopeningsinwallsofsafetyrelatedstructures arelocatedatelevation517.5ftMSL.Therearenoexteriorfloodprotectionbarriers(i.e.,levees,dikes, gates)thatwillpreventfloodingatthesite.TheDresdenStationsexternalfloodmitigationstrategyisto preventlossofsafeplantcontrolthatcouldbecausedbytheProbableMaximumFlood(PMF)oftheIllinois andKankakeeriversthroughtheimplementationofafloodemergencyprocedure.Thefloodemergency procedureentailsthesafeshutdownoftheplant.ThePMFisestimatedtoreachapeakStillwaterElevation of524.5ftMSL.WindgeneratedwavesontheKankakeeRiverwouldbe2.6feethighandwaverunup would reach 3 feet above stillwater level, increasing the maximum water surface elevation to approximately 528 ft MSL (Reference 10). As a result, predicted maximum water surface elevations are significantly above both the plant grade elevation and the lowest opening leading to safetyrelated equipment.Itisalsoestimatedthattheplantwouldexperienceflooding(waterelevationsgreaterthanthe designplantgradeof517.0ftMSL)for57hours,andwillrequiretheemergencydieselmakeuppumpto providemakeupwatertotheisolationcondensersforatleast78hoursbeforethefloodwaterrecededto elevation509ftMSLandadditional12hourstoallowforservicewaterpumpmotorstobereinstalled.The CLBalsoconsideredtheaffectsofalocalintenseprecipitation(LIP)onsitedrainage.

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c. Requested Actions PerEnclosure4ofReference3,theNRCrequeststhateachlicenseeconfirmuseoftheindustrydeveloped, NRCendorsed,floodwalkdownprocedures

orprovideadescriptionofplantspecificwalkdownprocedures.

In a letter dated June 11, 2012 (Reference 1), Exelon confirmed that the flooding walkdown procedure (Reference2),endorsedbytheNRConMay31,2012,willbeusedasthebasisforthefloodingwalkdowns.

OtherNRCrequestedactionsinclude:

(1) PerformfloodprotectionwalkdownsusinganNRCendorsedwalkdownmethodology; (2) Identifyandaddressplantspecificdegraded,nonconforming,orunanalyzedconditions,aswellas cliffedge effects, through the corrective action program, and consider these findings in the Recommendation2.1hazardevaluations,asappropriate; (3) Identifyanyotheractionstakenorplannedtofurtherenhancethesitefloodprotection; (4) Verifytheadequacyofprograms,monitoringandmaintenanceforprotectionfeatures;and (5) ReporttotheNRCtheresultsofthewalkdownsandcorrectiveactionstakenorplanned. of Reference 3 also states, if any condition identified during the walkdown activities represents a degraded, nonconforming, or unanalyzed condition (i.e., noncompliance with the current licensingbasis)foranSSC,describeactionsthatweretakenorareplannedtoaddresstheconditionusing theguidanceinReference6,includingenteringtheconditioninthecorrectiveactionprogram.Reporting requirementspursuantto10CFR50.72shouldalsobeconsidered.

d. Requested Information PerEnclosure4ofReference3,

1. TheNRCrequeststhateachlicenseeconfirmthatitwillusetheindustrydeveloped,NRCendorsed, flooding walkdown procedures or provide a description of plantspecific walkdown procedures.

ExelonsletterdatedJune11,2012(Reference1),confirmedthatthefloodingwalkdownprocedure (Reference2),endorsedbytheNRConMay31,2012,willbeusedasthebasisfortheflooding walkdowns.

2. The NRC requests that each licensee conduct the walkdown and submit a final report which includesthefollowing:

a. Describe the design basis flood hazard level(s) for all floodcausing mechanisms, including groundwateringress.

b. Describe protection and mitigation features that are considered in the licensing basis evaluationtoprotectagainstexternalingressofwaterintoSSCsimportanttosafety.

c. Describeanywarningsystemstodetectthepresenceofwaterinroomsimportanttosafety.

d. Discuss the effectiveness of flood protection systems and exterior, incorporated, and temporary flood barriers. Discuss how these systems and barriers were evaluated using the acceptancecriteriadevelopedaspartofRequestedInformationitem1.h.

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e. Presentinformationrelatedtotheimplementationofthewalkdownprocess(e.g.,detailsof selectionofthewalkdownteamandprocedures,)usingthedocumentationtemplatediscussed inRequestedInformationitem1.j,includingactionstakeninresponsetothepeerreview.

f.

Results of the walkdown including key findings and identified degraded, nonconforming, or unanalyzed conditions. Include a detailed description of the actions taken or planned to addresstheseconditionsusingtheguidanceinRegulatoryIssuesSummary200520,Revision1, Revision to NRC Inspection Manual Part 9900 Technical Guidance, "Operability Conditions AdversetoQualityorSafety,"includingenteringtheconditioninthecorrectiveactionprogram.

g. Documentanycliffedgeeffectsidentifiedandtheassociatedbasis.Indicatethosethatwere enteredintothecorrectiveactionprogram.Alsoincludeadetaileddescriptionoftheactions takenorplannedtoaddresstheseeffects.SeenoteinSection1aregardingtheNRCschangein positiononcliffedgeeffects.

h. Describe any other planned or newly installed flood protection systems or flood mitigation measures including flood barriers that further enhance the flood protection. Identify results andanysubsequentactionstakeninresponsetothepeerreview.

3. METHODOLOGY

a. Overview of NEI 1207 (Walkdown Guidance)

InacollaborativeeffortwithNRCstaff,NEIdevelopedandissuedreport1207(Rev0A),Guidelinesfor PerformingVerificationWalkdownsofPlantProtectionFeatures,datedMay2012(Reference2).TheNRC endorsed NEI 1207 on May 31, 2012 with amendments. NEI 1207 was updated to incorporate the amendments and reissued on June 18, 2012. On June 11, 2012, Exelon issued a letter to the NRC (Reference1)statingthattheendorsedfloodingwalkdownprocedure(Reference2)willbeusedasthe basisforthefloodingwalkdowns.NEI1207providesguidanceonthefollowingitems:

Definitions o IncorporatedBarrier/Feature o TemporaryBarrier/Feature o ExteriorBarrier/Feature o CurrentLicensingBasis(CLB) o DesignBases o Inaccessible o RestrictedAccess o Deficiency o FloodProtectionFeatures o ReasonableSimulation o VisualInspection o CliffEdgeEffects o AvailablePhysicalMargin o VarietyofSiteConditions o FloodDuration

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Scope o BasisforEstablishingWalkdownScope o IdentifyFloodProtectionFeatures(WalkdownList)

Methodology o DevelopWalkdownScope o PrepareWalkdownPackages o WalkdownTeamSelectionandTraining o PerformPreJobBriefs o InspectionofFloodProtectionAndMitigationFeatures General IncorporatedorExteriorPassiveFloodProtectionFeatures IncorporatedorExteriorActiveFloodProtectionFeatures TemporaryPassiveFloodProtectionFeatures TemporaryActiveFloodProtectionFeatures ProcedureWalkthroughandReasonableSimulation o ReviewoftheMaintenanceandMonitoringofFloodProtectionFeatures o ReviewofOperatingProcedures o DocumentationofAvailablePhysicalMargins o DocumentingPossibleDeficiencies o RestrictedAccess,orInaccessible AcceptanceCriteria EvaluationandReportingResultsofTheWalkdown RelatedInformationSources Examples WalkdownRecordForm SampleTrainingContent WalkdownReport

b. Application of NEI 1207 Exelonsapproachtothefloodingwalkdownsincludedthreephases:

Phase1-Preparation,Training,DataGathering,andScoping Phase2-InspectionsandReasonableSimulations Phase3-FinalReporting ThepurposeofPhase1wastoobtainaclearunderstandingofthesitesfloodmitigationstrategy;develop scope, methodology, and acceptance criteria for the walkdowns; and logistical planning. The following activitieswereperformedduringPhase1:

Datagathering(CLBdocuments,procedures,andO&Mproceduresanddocumentation);

Sitevisittopreviewfeaturesandplantconditions; DesktopreviewofCLBdocumentstoidentifyanddescribetheCLBfloodhazard; DesktopreviewofCLBdocumentstoidentifyanddescribefloodprotection/mitigationstrategy; DevelopmentofWalkdownList; Page8

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DevelopmentofWalkdownmethodologyandacceptancecriteria; Logisticsandstrategyplanning;and PreparationofWalkdownPackages.

ThepurposeofPhase2wastoexecutetheFloodingWalkdownforDresden,whichincluded:

VisualInspection; ReasonableSimulation; Evaluationofmaintenance/monitoringprocedures;and Documentationofobservationsandpossibledeficiencies.

ThepurposeofPhase3istodeveloptheWalkdownReporttodocumentthemethodologyandfindingsof the Flooding Walkdowns and provide a response to Requested Information section of the Recommendation 2.3: Flooding enclosure from the 10CFR50.54 (f) letter. The Walkdown Report was developedperthetemplateprovidedinNEI1207[Rev.0A],AppendixD.

c. Reasonable Simulations A procedure walkthrough, or Reasonable Simulation, was conducted for temporary and/or active features that require manual/operator actions to perform their intended flood protection function. The purpose of the reasonable simulations was to verify the procedure or activity can be executed as specified/written.PerNEI1207(Reference2),reasonablesimulationincludedthefollowing:

Verifythatanycreditedtimedependentactivitiescanbecompletedinthetimerequired.Time dependentactivitiesincludedetection(somesignalthattheeventwilloccur,hasoccurred,oris occurring), recognition (by someone who will notify the plant), communication (to the control room),andaction(byplantstaff).

Verifythatspecifiedequipment/toolsareproperlystagedandingoodworkingcondition.

Verifythatconnection/installationpointsareaccessible.

Verifythattheexecutionoftheactivitywillnotbeimpededbytheeventitisintendedtomitigate or prevent. For example, movement of equipment across unpaved areas on the site could be impededbysoftsoilconditionscreatedbyexcessivewater.

Reviewtherelianceonthestationstafftoexecuterequiredfloodprotectionfeatures.Ifduringthe review several activities are identified to rely on station staff, then perform and document an evaluationoftheaggregateeffectonthestationstafftodemonstrateallactionscanbecompleted asrequired.

Verify that all resources needed to complete the actions will be available. (Note that staffing assumptionsmustbeconsistentwithsiteaccessassumptionsinemergencyplanningprocedures.)

Showthattheexecutionoftheactivitywillnotbeimpededbyotheradverseconditionsthatcould reasonably be expected to simultaneously occur (for example, winds, lightning, and extreme air temperatures).

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Personnel/departments that have responsibility for supporting or implementing the procedure shouldparticipateinthesimulationeffort.

The simulation should demonstrate that the personnel assigned to the procedure do not have otherdutiesthatcouldkeepthemfromcompletingtheirfloodprotectionactivitiesduringanactual event.Actionsthatwouldbeperformedinparallelduringaneventshouldbesimulatedinparallel; notcheckedindividuallyandtheresultscombined.

Reasonablesimulationneednotrequiretheactualperformanceofthenecessaryactivitiesifthey havebeenpreviouslyperformedanddocumentedorithasbeenperiodicallydemonstratedand documentedthattheactivitiescanbecompletedinthecreditedtime.

The Flooding Walkdown activities for Dresden predominantly involved reasonable simulations since the floodmitigationstrategyistoexecutethefloodemergencyprocedure,whichpreparestheplantforsafe shutdownpriortotheadventoftheCLBfloodevent.Thefollowingcategoriesofreasonablesimulations wereperformed:

Simple Simulations - simulations/walkthroughs with short performance times that have been previously performed, and for which records are available to document the successful implementationoftheprocedureinthecreditedtime.

Complex Simulations simulations/walkthroughs with long performance times that have been previously performed, and for which records are available to document the successful implementationoftheprocedureinthecreditedtime.

DrillsorExercises-activitiesthathavenotbeenperformedbeforerequiretheactualperformance oftheactivitytodemonstratethattheycanbecompletedinthecreditedtime.

Records/DesktopEvaluationforproceduresthatareconsideredstandardoperatingprocedures, suchasplantshutdownprocedures.Onlytheportionsoftheseproceduresthatareapplicableto the flood response should be validated. The validation/evaluation should include review of past performance records to verify that the procedure can be executed in the credited time. The evaluation should also include the possible effect flooding conditions on execution of the procedureandwhethertheavailablewarningtimeissufficienttoexecutetheprocedure.

Aspartofthereasonablesimulations,visualinspectionswereperformedtoverifythattools,materials,and components required to execute the procedures were in working order, stored, and accessible per the requirementsoftheprocedures.

TheReasonableSimulationWorksheetsandWalkdownRecordFormswereusedtodocumenttheresultsof thereasonablesimulations.

Overall,nineteen(19)reasonablesimulationsofproceduralstepsorstandardshutdownprocedureswere performed to demonstrate compliance with the CLB requirements. Table 1 provides a summary of reasonable simulations performed during the walkdown. A detailed description of each reasonable simulationisprovidedinSection4.dofthisreport.

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Table1:ListofReasonableSimulations Simulation#

SimulationName 1

FloodWarning&FloodWatch 2

DieseldrivenEmergencyMakeupPump(movingandstaging) 3 ConstructionofSandbagBermaroundtheIsolationCondenserMakeupPumpsBuilding 4

DeenergizeMotorControlCenters(MCCs) 5 ManualOperationoftheIsolationCondensers 6

PreparefortheRemovalofSWPMotorsandSecure23SWPs 7

RaiseWaterStorageTankLevel&Check/FillBelowgroundWaterStorageTanks 8

RestoreReactorVesseltoNormalWaterLevel 9

SealDieselOilStorageTankVents 10 SecureIsolationCondenserPumps 11 Unit1-DFPControlSwitchOffSecureEquipment,SecurePowertoPC5 12 Unit1PostIncidentPump 13 Close/OpenFireProtectionSystemValves 14 OpenPlantDoors 15 PlaceLocalIsolationCondenserSightglassintoService 16 LossofSpentFuelPoolCooling 17 ReactorScram 18 ReactorVesselSlowFill 19 UnitShutdown

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d. Walkdown Inspection Guidance A Walkdown Inspection Guidance was developed by Exelon to supplement NEI 1207 (Reference 2),

based largely on Appendix A of NEI 1207 (Examples). The guidance was intended to supplement, not supersede,NEI1207andprovideinspectionguidanceforspecificfeatures,listedbelow.

IncorporatedorExteriorPassiveFeatures:

o SiteElevationsandTopography o EarthenFeatures(i.e.,FloodProtectionBerm,Dike,Levee) o ConcreteandSteelStructures o Wall,Ceiling,andFloorSeals(e.g.PenetrationSeals,CorkSeals) o PassiveFloodBarriersorWaterDiversionStructures o DrainsandCatchBasins o PlugsandManholeCovers o DrainagePathways(Swales,SubsurfaceDrainageSystem,etc.)

o PipingandCableVaultsandTunnels,ElectricalCableConduit o FloorHatches o FlapGate/BackwaterValve/DuckbillValve o FloodWall IncorporatedorExteriorActiveFeatures:

o CreditedWatertightDoors o CreditedNonWatertightDoors o Pumps o WaterLevelIndication o GateValves TemporaryPassiveFeatures:

o PortableFloodBarriersandInflatableRubberSeals o FloodGate TemporaryActiveFeature o Pumps

4. RESULTS TheinformationrequestedinReference3,Enclosure4,underparagraph2oftheRequestedInformation section,isprovidedbelow.ThecontentsofeachitemweredevelopedinaccordancewithReference2, AppendixD.

a. Requested Information Item 2(a) - Design Basis Flood Hazards Describe the design basis flood hazard level(s) for all floodcausing mechanisms, including groundwater ingress.

The design basis flood hazard level for the Dresden site has been evaluated by the NRC as part of the SystematicEvaluationProgram(SEP)TopicsII3.A,II3.B,II3.B.1andII3.C,whichwascompletedin1982.

TheresultsoftheSEPstudywerepresentedintheSafetyEvaluationReport(Enclosure1)andTechnical Page12

NTTFRecommendation2.3(Walkdowns):Flooding ExelonCorporation November20,2012 Revision0

EvaluationReport(Enclosure2).BasedontheinformationprovidedintheSEPreport,thedesignbasisflood hazard level is associated with the PMF, which results in a peak stillwater elevation of 524.5 ft MSL.

Coincidental2yearwindgeneratedwavesandwaverunupwouldincreasethemaximumwatersurface elevationtoapproximately528ftMSL.Bothfloodelevationsaresignificantlyabovethegradeelevation (517.0ftMSL),theelevationofnonwatertightopeningsinwallsofsafetyrelatedstructures(517.5ftMSL),

andthelowestsubgradefloorcontainingequipmentimportanttosafety(CribHouse)(509.0ftMSL).

ThepeakflowrateforthePMFwasdeterminedbyestimatingthewatershedsresponsetotheProbable MaximumPrecipitation(PMP),followingtheproceduredescribedinEM1110021411.ThePMPusedin theanalysiswasbasedona23.25inch,24hourindexstormdistributedover72hours.UsingtheUSACE HEC1software,thepeakdischargeintheIllinoisRiverwasestimatedtobe490,000cfs.ThePMFpeak discharge for the Illinois River was used in the USACE HEC2 computer program to compute the correspondingfloodstageatthesite.TheHEC2modelwascalibratedtorecordedhighwatermarksfrom the1947and1957floods.ThePMFhydrograph,presentedinEnclosure2oftheSEPreport,indicatesthat theplantwouldexperiencefloodingconditions(elevationsgreaterthan517.0ftMSL)forapproximately57 hours.FloodingofSSCswouldbeginatriverflowsbetween240,000cfsand290,000cfs(Reference10).The PMF hydrograph is provided in Figure 2 and is annotated with the corresponding flood elevations and timing.

InadditiontoestimatingfloodhazardlevelsassociatedwiththePMF,theSEPreportevaluatedtheflood hazard for LIP (i.e., site drainage flooding) and determined that the 29acre study area can produce an estimatedpeakdischargeof1,230cfsfromtheLIP.Twositedrainagescenarioswereevaluatedtoestimate thedepthoffloodingadjacenttothebuildings.ThefirstassumedthatfloodingfromaLIPwithinthethree drainageareasoccurredsimultaneouslyandwascombinedandroutedthroughasingledrainagechannel.

An evaluation of the drainage channel determined that the channel could convey the peak flow rate associatedwiththeLIPevent.Thesecondanalysesevaluatedthedrainagecharacteristicsofthesiteand between the buildings. The results of the analysis showed a peak flood depth of 0.45 ft. Since the difference in elevation between the land surface and the finished floor of the buildings 0.5 ft, there is approximately0.05ftoffreeboardduringtheLIPeventbeforesafetyrelatedequipmentisaffected.The affectsoftheLIPeventonroofstructureswasalsoevaluated.Noneoftheroofsofsafetyrelatedstructures were designed to sustain LIP loading with the drains clogged. As such, the NRC recommended that structuralmodificationsbecompleted(Reference10).Scuppersintheroofparapetsoftheturbinebuilding, reactorbuilding,andthecribhousewereinstalledtocomplywiththerecommendation.

TheSEPreportindicatesthatnormalgroundwaterlevelsatthesitearebetweenelevations505and508ft MSLandthedesignbasisgroundwaterelevationis514ftMSL.However,supportingdocumentationforthe determinationofthedesignbasisgroundwaterelevationwasnotprovided.TheNRCacknowledgedthat thegroundwaterlevelsintheplantareaarecontrolledbythewaterlevelsintheadjacentwaterbodiesand that the groundwater elevation of 514 ft MSL may be a reasonable estimate. Regardless, the NRC recommendedthatadesignbasisof517ftMSLbeusedincombinationwithseismiceventstoevaluate structuralstabilityandintegrityofthebuildings.

According to the UFSAR (Section 3.4.1.1), the structures for Units 2 and 3 were designed to withstand hydrostaticloads,includingthoseassociatedwithextremegroundwaterelevations,uptotheplantgrade elevation.Oncefloodingreachesabovetheplantelevation,thenfloodingoftheinteriorofthestructures, whichwilloccurpertheCLB,ispostulated.ThishasbeenpreviouslyreviewedandassessedbytheNRC(SEP report,TopicIII3.A),whichstatesthatfloodsorhighwaterlevelwillnotjeopardizethestructuralintegrity oftheplantsseismicCategoryIstructuresandthatthesestructuresareadequatelyprotected.Forthe Page13

NTTFRecommendation2.3(Walkdowns):Flooding ExelonCorporation November20,2012 Revision0

purposeofthefloodingwalkdowns,groundwateringresswasnotidentifiedasaplausiblefloodcausing event since there are no penetrations or flood protection features credited with providing a barrier to preventagainstgroundwateringresswereidentifiedintheCLBdocuments.However,sincetheCLBdid identify the plant basement walls as being designed to withstand hydrostatic loading, the flooding walkdownincludedvisualinspectionofthebelowgradestructures(i.e.basementwallsandfloorslabs)to verifytherearenopotentialobservablephysicaldeficiencies(i.e.cracking,spalling,ordegradedconcrete) thatmayimpactthestructuresabilitytowithstandhydrostaticloads.Thepurposeofthevisualinspection issolelytoverifythestructuralintegrityofthewallsandfloorslabs,includinganyassociatedpenetrations andseals.TheCLBdoesnotidentifythewallasabarriercreditedtopreventgroundwateringressand, therefore,potentialpenetrationsthroughthewallbelowgradewerenotincludedasindividualfeatureson theWalkdownList.Penetrationsandassociatedsealswereinspectedasacomponentofthewalltoidentify if there are any observed degraded conditions. Any degraded conditions related to penetrations were recordedontheFieldObservationReportandattachedtotheWalkdownRecordFormfortheassociated wallfeature.

Iceinducedfloodingwasnotidentifiedasaconcernforsafetyrelatedequipment.Alogboomislocatedat theentranceoftheintakecanalstopreventfloatingicechunksfromreachingtheintakestructures.The reachoftheKankakeeRiverupstreamfromtheconfluenceoftheDesPlainesRiveriskeptfreefromiceto maintainclearshippinglanes.Inaddition,nofloodingproblemshavebeenrecordedinthepast.

Noadditionalfloodcausingevents,whichcouldresultinafloodhazardforthesafetyrelatedequipment, wereidentifiedintheCLBdocuments.

SinceDresdenStationisnotconsideredaflooddrysite(i.e.,thesitewillbeinundatedduringthedesign basisPMFevent),thefloodingstrategyprimarilyinvolvesimplementationoffloodemergencyprocedures tomitigatetheeffectsofthefloodandpreventdamagetothereactorcore.Sufficientfloodwarningis criticalforasuccessfulexecutionofthefloodemergencyprocedure,includingthesafeshutdownofboth reactors,removalofdecayheat,andstagingofemergencyequipmentforalternatereactorcooling.Two typesoffloodhydrographsarepresentedintheSEPreport,whichcanbeusedtoestimatetheminimum requiredfloodwarning:thePMFhydrograph(Figure2)andthecriticaltimehydrograph(Figure3).ThePMF hydrographandstagedischargecurveindicatesthatthetimebetweentheonsetofrainfallandthetime when the flood levels reach plant grade elevation is 51 hours5.902778e-4 days <br />0.0142 hours <br />8.43254e-5 weeks <br />1.94055e-5 months <br />. The plant would then continue to be inundatedfor57hoursanditwouldtakeanother23hoursforfloodelevationtorecedebelowelevation 509ftMSL.Thecriticaltimefloodhydrographdepictstherelationshipoffloodelevationtotimesincethe beginningofthelimitingrainfallevent.Thecriticaltimefloodisdefinedasthefloodduringwhichwater levelrisestoelevation509ftMSLandsubsequentlyto517.5ftMSL.Inaddition,thereportstatesthatthe timeframeinwhichsafeshutdown mustbeachievedisdetermined bythecriticalflood.Basedonthe criticaltimehydrograph,33hourswillbeavailablefromtheonsetofthelimitingrainfalleventuntilthe IllinoisRiverreacheselevation517.5ftMSLandbeginsfloodingthesafetyrelatedequipmentinthemain reactorbuilding.Forthepurposeofthewalkdown,theshortesttimeperiod,asrepresentedonthecritical timehydrograph,shouldbeusedtoevaluatewhethertheprocedurecanbeexecutedasspecified.The duration of the flood was evaluated based on the time period as determined by the PMF hydrograph.

However, additional considerations were given to procedural steps completed between water surface elevations509ftMSLand517ftMSL.ThePMFhydrographshowsthatonly7hourswillbeavailableto completetherequiredactivitiesbeforefloodwatersrisefrom509ftMSLto517ftMSL.Thistimeframeis shorterthaninthecriticaltimehydrograph,whichshows11hoursforfloodwaterstorisefrom509ftMSL to 517.5 ft MSL. Because the criticaltime and PMF hydrographs appear to control procedures and Page14

NTTFRecommendation2.3(Walkdowns):Flooding ExelonCorporation November20,2012 Revision0

resourcesatdifferentfloodelevations,thetimeperiodtoimplementthesetaskswereevaluatedagainst bothhydrographstoestablishtheshortesttimeavailabletoachievesafeshutdownofthereactor.

TheCLBdoesnotaddressspecificplantconfigurationsduringvariousmodesofoperation.However,afull power operation mode was considered during the evaluation, as this represents the most critical plant failuremode.

Figure2:PMFHydrographfromtheSEPreport(annotatedwiththecorrespondingfloodelevationsandtiming).

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NTTFRecommendation2.3(Walkdowns):Flooding ExelonCorporation November20,2012 Revision0

Figure3:CriticalTimeHydrographfromtheSEPreport.

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NTTFRecommendation2.3(Walkdowns):Flooding ExelonCorporation November20,2012 Revision0

b. Requested Information Item 2(b) - CLB Protection and Mitigation Features Describeprotectionandmitigationfeaturesthatareconsideredinthelicensingbasisevaluationtoprotect againstexternalingressofwaterintoSSCsimportanttosafety.

TheDresdenStationisinundatedduringthePMFeventandexternalfloodmitigationeffortsaredirected towardthepreventionofdamagetothereactorcoreduringfloodingconditions.Inaddition,thestructures forUnits2and3aredesignedtowithstandhydrostaticloads,combinedwithotherapplicableloads,upto gradeelevationof517ftMSL.TheexternalfloodprotectionprocedureforDresdenmakesuseofonsite equipmenttoachieveasafeshutdownofthereactorandrequirestheopeningofalldoorstopermitfree flow of water through the plant. Along with this, the procedure utilizes the reactor cooling systems to dischargedecayheatthroughoutthetermofthePMF.

Thefloodemergencyprocedure(DOA001004)iscreditedintheCLBdocumentsastheprotectionmeasure availabletominimizetheimpactofanexternalfloodevent.Theprocedurerequiresthatactionsorother proceduresareinitiatedwhenthefloodwatersreachcertainelevationstosuccessfullymaintainthereactor coreinasafeandstablecondition.Thefollowingparagraphsprovideasummaryofthefloodemergency procedureandthemainactionsthatareinitiatedwhenfloodwatersreachacertainelevation.

TheprocedureisinitiatedbyafloodforecastbytheU.S.WeatherService,notificationofpredictedrainfall exceeding2inchesin6hoursorforactualwaterlevelsexceedingelevation506ftMSLintheUnit2/3Crib House.Consequently,floodmonitoringisconductedatleastonceevery2hours.Sincethelowestopening toequipmentimportanttosafetyisatelevation509ftMSL,proceduresforUnitShutdown(DGP0201)and VesselSlowFill(DGP0202)areinvokedwhenriverlevelsarepredictedtoexceedelevation509ftMSL within three days.ReactorScram (DGP0203)andVesselSlowFill(DGP0202)areinitiatedshould the floodlevelsreachelevation509ftMSLandasufficientfloodwarningwasnotissuedtoallownormalunit shutdown. In, addition, a flood protection sandbag berm is constructed around the isolation condenser makeup pumps building. When flood levels reach elevation 509 ft MSL additional steps are initiated, including:

RemovaloftwoUnit2servicewaterpumpmotorstorelocateabove530ftMSLtoallowthemto beavailableforserviceoncethefloodrecedes.

StagingofthedieseldrivenemergencymakeuppumpinthecenterofUnit2ReactorBuilding equipmenthatchonelevation517.5ftMSLandsettingupthepumpforoperation,includinglifting ofthepumpusingacraneandbuildingofscaffolding.

Configuringofvalvesinthefireprotectionsystemtoallowforconnectionofpumptothesystem.

Once flood water levels reach an elevation of 513 ft MSL, additional procedures are initiated to secure servicewaterpumps(DOP390001),transferreactorcoolingtoisolationcondenser(DOP130003),andto initiateplanstoaddresslossoffuelpoolcooling(DOA190001)andAttachmentCofthefloodprotection procedure(DOA001004).

Oncefloodwaterlevelsreachanelevationof517ftMSL,alltransformersandelectricalequipmentwillbe deenergizedandreactordoorswillbeopenedtopermituninhibitedwaterflowthroughtheplant.Several otheractionsareperformedpriortothiswhentheriverlevelsarepredictedtoexceed517ftMSL,including Page17

NTTFRecommendation2.3(Walkdowns):Flooding ExelonCorporation November20,2012 Revision0

sealingofventsonbelowgrounddieseloilstoragetanks,fillingofbelowgroundwaterstoragetankswith demineralizedwater,andsecuringofmotorboatsfortransportation.

Thedieseldrivenemergencymakeuppumpwouldbestartedprovidingmakeupwatertotheisolation condenserusedforcoolingofthereactorswhenthefloodlevelreacheselevation518ftMSL.Thepump willcontinuetooperateuntilwaterrecedesbelowanelevation509ftMSLandtwoservicewaterpumps areinstalledandmadeoperational.Thepumpwillbeattachedtoacraneandraisedandloweredasthe floodlevelrisesandrecedes.

Basedonthecriticaltimehydrograph,approximately33hoursaftertheonsetofthelimitingrainfallevent waterlevelswillreachanelevationof517.5ftMSLandbeginfloodingsafetyrelatedequipmentlocatedin the main reactor building. As such, it is critical that available instrumentation and forecasting data pertainingtoregionalprecipitationandwaterlevelrisearemonitoredtoensureadvancedwarninginthe eventofthePMForthecriticalflood.

While not specifically mentioned in the CLB, belowgrade walls and slabs of the reactor and turbine buildings were considered to be flood protection features at Dresden Station. These structures and the associatedpenetrationsareintendedtopreventgroundwateringressintothespacecreditedasdrybefore floodwatersreachelevation517.5andbeforeexteriordoorsareopenedtoallowfreeflowofwaterinto thebuilding.Itiscritical,however,thatthebelowgradestructuresprovideprotectionagainstgroundwater ingresssincesafetyrelatedSSCsarelocatedinbasementareasofreactorandturbinebuildings.TheseSSCs arecreditedwithmaintainingreactorcoolinguntiltheemergencypumpisusedtoprovidemakeupwater for the isolation condensers and groundwater ingress prior to the shutdown of both units could affect plantsimplementationofthefloodemergencyprocedure.TheCLBdocumentsdonotindicatethatStation sump pumps were installed to control groundwater ingress. Furthermore, the sump pumps do not penetratethroughbasementfloorslabsand,therefore,theywerenotincludedinthescopeoftheflooding walkdown.

c. Requested Information Item 2(c) - Flood Warning Systems Describeanywarningsystemstodetectthepresenceofwaterinroomsimportanttosafety.

Sincethesiteisallowedtobeflooded,warningsystemsinroomsimportanttosafetyarenotcreditedin theplantsexternalfloodinglicensingbasisandwerenotidentifiedaspartofthewalkdown.Accordingto thefloodemergencyprocedure,risingfloodlevelswouldbemonitoredatleastonceeverytwohoursonce theintakecanallevelexceeds506ftMSL.Frequentmonitoringoffloodlevelsiscriticalforinitiationof certainfloodemergencyactionsandthesuccessfulimplementationofthefloodemergencyprocedure.In additiontofrequentmonitoringoffloodlevelsattheintakebay,plantstaffwouldcommunicatewiththe DresdenLockMasteronaregularbasistodetermineactualfloodlevelsonsite.Itisexpectedthatoncethe Unit2/3CribHouseisflooded,thesitewouldhavetorelyontheDresdenLockMastertoreportactual floodlevelsonsite.

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d. Requested Information Item 2(d) - Flood Protection System/Barrier Effectiveness Discuss the effectiveness of flood protection systems and exterior, incorporated, and temporary flood barriers.Discusshowthesesystemsandbarrierswereevaluatedusingtheacceptancecriteriadevelopedas partofRequestedInformationItem1.h[inEnclosure4oftheMarch12,2012,50.54(f)letter]

Section6ofNEI1207definesacceptanceas:

Flood protection features are considered acceptable if no conditions adverse to quality were identified during walkdowns, verification activities, or program reviews as determined by the licenseesCorrectiveActionProgram.Conditionsadversetoqualityarethosethatpreventtheflood protection feature from performing its credited function during a design basis external flooding eventandaredeficiencies.DeficienciesmustbereportedtotheNRCintheresponsetothe50.54(f) letter.

AsindicatedinSection3d,inspectionguidancewasdeveloped,supplementingNEI1207,toprovidemore specificcriteriaforjudgingacceptance.Allobservationsthatwerenotimmediatelyjudgedasacceptable wereenteredintothesitesCorrectiveActionProgram(CAP)whereanevaluationoftheobservationcanbe made.

As described in Section 4 b, Dresden Stations flood protection strategy against external flooding is governedbyafloodemergencyprocedure.Thefloodemergencyprocedureinvokesotherproceduresand actionsintendedtosafelyshutdownthereactor,protectthereactorcoreandprovidemakeupcooling duringthedesignbasisfloodwhenothercoolingsystemsarenotoperational.Theevaluationoftheflood emergencyprocedurewasperformedinaccordancewithNEI1207guidelinesusingtheacceptancecriteria developed prior to the execution of the walkdown. Due to the complexity of the flood emergency procedure,theevaluationofitseffectivenesswasperformedbyfirstevaluatingindividualproceduralsteps and actions during the walkdown, followed by a desktop evaluation of the procedure as a whole. The individualproceduralstepsandactionsweredrilledorsimulatedduringthewalkdowntoverifythatthe actions can be completed in the credited time and to estimate the manpower resources required to complete the task. The desktop evaluation of the flood emergency procedure included evaluation of availableresourcesbasedonpaststaffinglogsandestimatesofstaffavailabletorespondtoemergency.

Thissectionisdividedintothefollowingsubsections:

1. FieldevaluationofFloodEmergencyProcedure-evaluationofeffectivenessofproceduralsteps and actions based on reasonable simulations. Times stated for performing each procedure or procedural step were based on the actual performance of the drill/exercise or, in case of simulationsthatwereperformedinthepast,onanestimateprovidedbythestaffresponsiblefor executionoftheprocedure.

2. Desktop evaluation of Flood Emergency Procedure - evaluation of overall effectiveness of the entirefloodemergencyprocedure.

3. Evaluation of Incorporated Passive Barriers - evaluation of belowgrade walls and slabs against groundwateringress.

4. Site Topography - evaluation of site topography (i.e. contours, slopes, grades, imperviousness, structures,fences,etc.)againstthatassumedintheCLBsitedrainageevaluation.

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FIELDEVALUATIONOFFLOODEMERGENCYPROCEDURE FloodWarningandFloodWatch Floodwarningandfloodwatcharetwocriticalcomponentsofthefloodemergencyprocedure.The flood emergency procedure requires that Operations Supervisor monitors weather and flood forecast using available sources such as the National Weather Service (NWS) Chicago Office, USACE,andExelonsownweathermonitoringsystem.Inaddition,ExelonsTransmissionSystem OperatorwouldalertDresdenStationofanysevereweatherconditionstooccurinthearea.The floodemergencyprocedurespecifieswhatactionsneedtobetakenifadverseweatherconditions orfloodconditionsareforecastwithinacertaintimeperiod.

PlantOperatorsalsomonitorriverlevelsattheUnit2/3CribHouseevery24hours.Themonitoring frequency increases when river levels exceed certain elevation to ensure that there is sufficient floodwarningandtimeforimplementationoffloodemergencyactions.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantity ofResources DurationofResourcesRequiredto PerformTask 1)

EquipmentOperator 1

Continuousmonitoringoffloodlevels 2)

OperationsSupervisor 1

Continuousmonitoringofflood&

weatherforecast

ThewalkdownteaminterviewedtheOperationsSupportManagertoevaluatewhetherplantstaff isknowledgeableofproceduralstepsrelatedtofloodwarningandfloodwatchandwhetherthe plant can receive sufficient flood warning to allow for successful implementation of the flood emergencyprocedure.BasedonAMECsevaluation,thesitehasresourcesandabilitytomonitor weatherconditionsandfloodinginrealtime;however,theabilitytopredictfloodlevelsatthesite appearstobelimited.Thisisdueinparttovariablesthataffecttheabilitytopredictriverlevelsat theDresdenIntake,suchasoperationofthelockanddamsbothupstreamanddownstreamofthe site.ThefloodemergencyprocedurestatesthatUnit2andUnit3reactorsshouldbeshutdown using the Unit Shutdown (DGP 0201) standard operating procedure and subsequent tasks are initiated when the river levels are predicted to exceed elevation 509 ft MSL within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

However,currentriverforecastingtoolsarenotabletoreliablypredictexactlywhen509ftMSLwill be exceeded at the Dresden intake. When reviewing available information, if Station personnel anticipatewaterlevelsexceeding509ftMSLanytimewithinthenext72hoursaplantshutdownis initiated.

The Flood Warning and Flood Watch procedural step can be implemented successfully by plant staff.TheOperationsSupportManagerinterviewedduringthewalkdownwasknowledgeableof theprocedureandwasabletoperformtherequiredactionsasspecified.Whileresourcesarenot availabletoaccuratelypredictriverlevelsattheDresdenintake,itisreasonabletoassumethata limitedfloodwarningcanbeobtainedfromDresdenLockMasterorusingriverforecastingtoolsfor the Illinois River watershed. In addition, the Flood Emergency Procedure is entered following a notificationfromTransmissionSystemOperatorpredictingrainfallof2inchesin6hours.This allows the site to initiate flood protection measures based on a rainfall forecast and/or limited floodwarning.

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DieseldrivenEmergencyMakeupPump(movingandstaging)

The dieseldriven emergency makeup pump (Godwin Model HL80) is used to provide makeup coolingfortheisolationcondensersoncefloodwatersexceedelevation518ftMSLperstep14.c.

Themakeuppumpisconnectedtoplantsfiresuppressionsystemandusesriverwaterassource ofmakeupwater.ThepumpislocatedintheEmergencyResponseOrganizationbarnandhoses andfittings,whicharerequiredtoconnectthepumptothefiresuppressionsystem,arelocatedin theSeaVansstoragecontainer.Oncethefloodwatersarepredictedtoreachorexceedelevation 509ftMSL,thepump,hoses,andfittingaremovedtothecenteroftheUnit2ReactorBuilding equipmenthatch.Thehosesarethenconnectedtothepumpandthefiresuppressionsystemis disengagedtoallowforconnectionofthehosestothefiresuppressionsystem.Finally,thepumpis rigged to the reactor building crane (or the jib crane) with a chain fall to ensure that it can be manuallymovedupanddownasthefloodwatersriseandrecede.Scaffoldingisbuiltuptoa15ft heighttoallowforoperationofpumpcontrolsandthechainfall.Sincethepumpisexpectedto operateforextendedperiodoftime,additionaldieselfuelsupplyisstagedontheflooratelevation 545ftMSL.Thedieselfuelwouldbethentransferredtotheemergencymakeuppumptankusinga handpump,hose,andafunnel.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources Required Quantityof Resources DurationofResources RequiredtoPerformTask 1)

MechanicalMaintenanceStaff 4

3.6hours 2)

MechanicalMaintenanceSupervisor 1

3)

EquipmentOperators 4

4)

OperationsSupervisor 1

Thewalkdownteamobservedadrillofthisproceduralstep,whichincludedmovingthemakeup pumpandhosesinsidetheprotectedarea,connectingthehoses,andhoistingthepumponacrane andraising/loweringthepumpusingthechainfall.AnalternativelocationintheMaintenanceShop wasselectedtoperformthedrillforhoistingthepumpsoplantoperationswerenotimpacted.

Connection of the pump and valve manipulation was reasonably simulated since the fire suppression system cannot be disengaged under full reactor operation. During the reasonable simulation,theMaintenancestaffwalkedAMECevaluatorsthroughtheprocedure,gatheredthe necessarytools,andwalkedtothelocationwherethemakeuppumpwouldbeconnectedtothe fire suppression system. The time for completion of the task was estimated based on previous performancecompletedaspartofstationsmaintenanceprogram.TheOperationsstaffidentified thevalvesthatneedtobeclosedpriortoconnectingtothefiresuppressionsystemandopened oncethemakeupisconnected.TheOperationsstaffalsodemonstratedhowthevalveswouldbe openedandclosedmanually.Theplanthassufficientsupplyofdieselfuelforthemakeuppump.

Diesel fuel is stored in a 4,000gallon aboveground storage tank from which it would be transferredintoempty55gallonbarrels.Thefloodemergencyprocedureassumesthat,basedon thefullloadfuelassumption,four55gallonbarrelswouldconservativelyprovideatwodaysupply of diesel fuel. However, the PMF hydrograph indicates that the makeup pump would have to operateatminimumofapproximately78hours(durationoffloodfromelevation519.5ftMSLuntil Page21

NTTFRecommendation2.3(Walkdowns):Flooding ExelonCorporation November20,2012 Revision0

theriverrecedestoelevation509ftMSL)andadditional12hoursuntilservicewaterpumpsare installed.Therefore,thesupplyofdieselfuelstagedinthereactorbuildingatelevation545ftMSL maynotbesufficienttoprovidecontinuousoperationofthemakeuppumpforatleast90hours beforethefloodwatersrecedebelowelevation509ftMSLandservicewaterpumpmotorsarere installed.

Theobserveddrills/exercisesandreasonablesimulationsindicatethattheDieseldrivenEmergency MakeupPumpproceduralstepcanbeperformedwithinthespecifiedtimeframe.TheOperations andMaintenanceStaffperformeddrills/exercisesorprocedurewalkthroughsanddemonstrated thattheyhaveagoodunderstandingoftheprocedureandcanperformthetasksasspecified.The minimumresourcesavailabletoperformtheprocedureareadequate;however,itwasnotedthat the flanged elbow fitting used as an alternate connection to the fire suppression system was missinganidentificationtag.ThefittingwasavailableintheSeaVanstorageandthemissingtag didnotimpactthestagingofthemakeupuppump.Basedonthesimulationitisanticipatedthatif needed,thisproceduralstepcouldbeperformedinashorterperiodoftimebyutilizingadditional staffthatwouldrespondtoanemergencywithin4hours.

ConstructionofSandbagBermaroundtheIsolationCondenserMakeupPumpsBuilding The sandbag berm is constructed around the isolation condenser makeup pumps building to preventfloodinguptoelevation519.5ftMSLwhenfloodwatersarehighenoughtobeusedasa sourceofmakeupwaterfortheisolationcondensers.Thefloodemergencyprocedurestatesthat suppliesforconstructionoftheberm(i.e.,sandandsandbags)wouldbeobtainedfromtheGrundy CountyEmergencyOperationsCenter;however,approximately3,000bagswereobtainedpriorto conductingthedrillandwillbestoredonsiteforfutureuse.Supplyofsandisstoredadjacentto thecontractorparkinglotanditismixedwithsaltforuseduringthewintermonths.Whilenot specifiedinthefloodemergencyprocedure,therequiredlengthofthesandbagbermtoprotect thenonwatertightdoorstobuildingis50linearfeet.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources Required Quantityof Resources DurationofResources RequiredtoPerformTask 1)

MechanicalMaintenanceStaff 5

8.5hours 2)

MechanicalMaintenanceSupervisor 1

TheMechanicalMaintenancestaffconstructedarepresentativesampleofthesandbagberminthe contractorparkinglot.Thewalkdownteamusedtherepresentativesampletoestimatethetimeto constructthe50ftlongbermduringthefloodemergency.TheMechanicalMaintenancestaffwere able to follow the instructions in the flood emergency procedure and construct the berm as specified.

Basedontheobserveddrill/exercise,thesandbagbermcanbeconstructedasspecified.However, conditionsduringamajorfloodareexpectedtobesignificantlymorechallengingandstaffmay experience fatigue and exhaustion, which might result in utilization of a greater number of resources.Highwindsanticipatedduringamajorfloodcouldpotentiallydispersesandbagmaterials Page22

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throughoutthesiteandrainwilllikelymakesandheavierandmoredifficulttohandle.Inaddition, a chainlink gate in front of the makeup pump building would have to be removed prior to constructingthesandbagberm.Theseadditionalconstraintsandadverseconditionsmayincrease resourcerequirements;however,thedurationofthetaskshouldnotbeaffectedsignificantly.In addition,constructionofthesandbagbermdoesnotrequireanyspecificskillsorknowledgeand anyavailablestaffcouldbedeployedtoperformthistasksuccessfully.

DeenergizeMotorControlCenters(MCCs)

SectionD.14.arequiresthatalltransformersandMCCsonelevation517ftMSLbedeenergized whentheriverlevelreacheselevation517ftMSL.Thispartoftheprocedureiscompletedinthe ControlRoom.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

ReactorOperators 2

20minutes

The Operations staff demonstrated the knowledge of the procedural step and the ability to successfullyperformtheproceduralstepaswritten;however,thisproceduralstepdoesnotclearly statewhichBusshouldbedeenergizednordoesitexplicitlystatewhichtransformersandMCCson elevation517ftMSLareimpacted.

Basedonthereasonablesimulation,theevaluatedproceduralstepcanbeperformedsuccessfully perSectionD.14.aandtheOperationstaffshowedsufficientknowledgeoftheactionneededtobe performed.

ManualOperationoftheIsolationCondensers Section D.12.b.(1) requires the transfer of Unit 2(3) cooling to the Isolation Condensers and to monitorandcontroloperationoftheIsolationCondenserswhenriverlevelreacheselevation513ft MSL.Thisstepwasevaluatedforaworstcasescenarioinwhichthesitehaslossofoffsiteandback upbatterypower.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

EquipmentOperators 2

45minutes

The Operations staff was able to successfully simulate procedural steps as written and no conflicts/issueswerefound.Theprocessoftransferringcoolingwatertotheisolationcondensersis anindependentprocessforeachunit,whichcanbedoneinparallel,ifneeded.The45-minute estimate to perform the task is the time duration for completing the task in parallel using one operatorforeachUnit.

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Basedonthereasonablesimulation,theevaluatedproceduralstepcanperformedsuccessfullyper SectionD.12.b.(1)andtheOperationstaffshowedsufficientknowledgeoftheactionneededtobe performed.

PreparefortheRemovalofSWPMotorsandSecure23SWPs Section D.9.c requires the preparation and removal of two Unit 2 Service Water Pump (SWP)

Motorstoberelocatedtoanareaaboveelevation530ftMSL.Thisstepisinitiatedwhentheriver levelreachesorispredictedtoreachelevation509ftMSL.AnElectricalMaintenanceSupervisor andaSeniorElectricianwalkedAMECevaluatorsthroughtheprocessstepbystep,showinghow componentswouldbesecured,disconnected,andtransportedtoanareaaboveelevation530ft MSL. Since the motors have been previously removed, a drill was not required. However, the electricianandthesupervisorprovidedreasonableestimatesoftimedurationsforcompletionof each step. Past maintenance records were also reviewed to verify the estimated times and a considerationwasgiventothefactthatcertainactionsmaybeperformedfasterduringaflood emergencythanduringascheduledmaintenanceoutage.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

MechanicalMaintenance 1

11.17hours 2)

ElectricalMaintenance 9

The Electrical Maintenance staff was able to successfully simulate completion of the procedural stepperSectionD.9.c.Itshouldbepointedout,however,thatthefloorofUnit2/3Cribhouseisat elevation 509.5 ft MSL and the procedure can be initiated as late as when river levels reach elevation509ftMSL.Underthisscenario,itislikelythattherewouldnotbeenoughtimetomove themotorstotheupperlevelbeforethefloodwatersinundatethelowerlevelsofthecribhouse.

Forinstance,thePMFhydrographestimatesthatthefloodlevelswouldrisefromelevation509ft MSLtoelevation513ftMSLinaslittleas3hoursandtheestimatedrequiredtimetomovethe motorstotheupperlevelisapproximately8hours(9hoursand11hours,respectively,tomove bothmotorstotheTurbineBuilding).ThistaskisNOTcriticalforensuringthatthereactorissafely shutdownandcoolingofthereactorismaintained.

Basedonthereasonablesimulation,theElectricalMaintenancestaffshowedsufficientknowledge and skills to successfully execute the task. However, assuming the that flood waters are rising accordingtothePMFhydrographandtheStationcannotrelyonthefloodwarning,theElectrical Maintenancestaffmaynothavesufficienttimetomovethemotorstotheupperlevelbeforethe CribHouseisinundated.Inaddition,thistaskcouldonlybeinitiatedafterthesufficientElectrical Maintenance staff has responded to the flood emergency (between 1 and 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after the issuanceoffloodemergency).

RaiseWaterStorageTankLevel&Check/FillBelowgroundWaterStorageTanks SectionsD.13.aandD.13.bstatethelevelinabovegroundwaterstoragetankswillberaisedtoa levelatleast10feetabovethegroundandthelevelinbelowgroundwaterstoragetankswillbe checkedandthestoragetankswillbefilledwithwater,ifneeded,whenriverlevelsarepredictedto exceedelevation517ftMSL.

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Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

ReactorOperator 1

2hours

TheOperationsstaffwasabletosuccessfullysimulatetheproceduralstepaswritten;however,the proceduredoesnotspecificallystatewhichtankstheactionsshouldbeperformedon.Theabove groundwaterstoragetanksaremaintainedabove50%capacityand,therefore,theywillalreadybe filledtotherequired10feet.

Basedonthereasonablesimulation,theevaluatedproceduralstepcanbeperformedsuccessfully perSectionsD.13.a,bandtheOperationsstaffshowedsufficientknowledgeandskillandwouldbe abletosuccessfullyexecutethetask.

RestoreReactorVesseltoNormalWaterLevel SectionD.12.brequiresthesitetorestorereactorvesselstonormalwaterlevelwhenriverlevels reachelevation513ftMSLandbeforereactorcoolingistransferredtotheisolationcondensers.

TheReactorWaterCleanup(RWCU)Blowdownmethodwouldbeusedtolowerthereactorwater level from 140 inches to 30 inches. However, reactor cooling could be transferred to isolation condenserswhenreactorwaterlevelisbelowtheisolationcondensersteamline(at66inches).

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

ReactorOperator 2

74minutes 2)

SeniorReactorOperator 1

The Operations staff were able to successfully simulate the procedural step as written with no conflictsorissues.Thedurationofthistaskwasbasedonanestimatedmaximumblowdownof200 gpm(perDOP120002)andreactorvolumeof200gal/in.

Basedonthereasonablesimulation,theevaluatedproceduralstepcanperformedsuccessfullyper SectionD.12.b.TheShiftUnitSupervisorshowedsufficientknowledgeandabilitytoperformthis stepintheprocedure.

SealDieselOilStorageTankVents SectionD.13.cstateswhenriverlevelsarepredictedtoexceedelevation517ftMSL,thesitewill sealtheventsonthebelowgrounddieseloilstoragetanks.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

MechanicalMaintenance 1

30minutes

The Mechanical Maintenance staff were able to successfully simulate the procedural step as writtenwithnoconflictsorissues.

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Basedonthereasonablesimulation,theevaluatedproceduralstepcanperformedsuccessfullyper SectionD.13.c.TheMechanicalMaintenancestaffshowedsufficientknowledgeoftheactionbeing performed.

SecureIsolationCondenserPumps SectionD.14.hstatesthatifthedieseldrivenemergencymakeuppumpisprovidingmakeupto the isolation condensers, then the isolation condenser makeup pumps should be secured. This action would occur the earliest when river levels are above elevation 519 ft MSL. The isolation condenserpumpsaresecuredfromthecontrolroom.Ifthecontrolroomdoesnothavepower,the pumpscanbesecuredmanually.Thisstepwasevaluatedfortheworstcasescenariobyhavingthe sitesecurethepumpsmanually.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

EquipmentOperator 1

25minutes

The Operations staff were able to successfully simulate the procedural step as written with no conflicts or issues. The possible concern is that during flooding conditions the access to the isolation condensers makeup pump building would likely require a boat, which could delay the executionofthetask.Securingoftheisolationcondenserpumpsis,however,NOTacriticalitem forsuccessfulimplementationoftheprocedure.

Basedonthereasonablesimulation,theevaluatedproceduralstepcanperformedsuccessfullyper SectionD.14.h.TheOperationsstaffshowedsufficientknowledgeoftheactionbeingperformed.

Unit1-DFPControlSwitchOffSecureEquipment,SecurePowertoPC5 SectionD.10.acstatesthatiftheriverlevelreacheselevation508ftMSL,thenthesitewillplace theUnit1DFPcontrolswitchintheoffpositiontopreventautomaticstartonlossofpower,secure alloftheUnit1equipmentfromPC5intheUnit1Cribhousebasement,andverifytwobreakers areopentosecurepowertoPC5.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

EquipmentOperator 1

20minutes

TheOperationsstaffwasabletosuccessfullysimulatetheproceduralstepaswritten.However, therewerefouradditionalcubiclesthatneededsecuringintheUnit1Cribhousebutwerenotlisted in the procedure. Also, some breakers nomenclature varied from what was specified in the procedure.Thebreakerswerestilllabeledsufficientlyenoughtoensurethatthecorrectbreakers aresecured.

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Basedonthereasonablesimulation,theevaluatedproceduralstepcanperformedsuccessfullyper Sections D.10.a.c. The Operations staff showed sufficient knowledge of the action being performed.

Unit1PostIncidentPump SectionD.13.estatesthatmechanicalmaintenanceistobedirectedtoremoveoneUnit1post incidentpumpoutofitswelltoprovideflowpathintotheUnit1sphereandtoequalizepressures onspherewalls.Thisproceduralstepistobeinitiatedwhenriverlevelsarepredictedtoexceed elevation517ftMSL.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

MechanicalMaintenance 2

3.08hours

These actions are performed to protect Dresden Unit 1 equipment. They are not required to supportDresdenUnit2andUnit3andarenotrequiredtobeaddressedinthe10CFR50.54(f) information request. The Mechanical Maintenance staff were able to successfully simulate the removalofthepostincidentpump;however,thereisnosetprocedureforremovalofthepump.

The Mechanical Maintenance personnel showed sufficient knowledge to perform this task but theremaybeminordifficultiessettingupriggingsincethetaskhasnotbeenperformedinthepast.

The estimated time to remove the pump is based on input provided by the Mechanical Maintenance supervisor. The time allocated for this procedural step ensures a detailed and thoroughremovalofthepump.

Basedonthereasonablesimulation,theevaluatedproceduralstepcanperformedsuccessfullyper Sections D.13.e. The Mechanical Maintenance staff showed sufficient knowledge of the action beingperformed.

Close/OpenFireProtectionSystemValves

SectionD.9.fstatessix(6)fireprotectionvalveswillbeclosedandtwo(2)openedonceothertasks arecompleted.Thisstepwillbeinitiatedwhentheriverlevelisatelevation509ftMSL.Avisual inspectionofthesevalveswasdonetoevaluatephysicalappearanceofthevalvesandaccessibility ofthevalves.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

EquipmentOperator 2

40minutes

The Operations staff were able to successfully simulate the procedural step as written and no conflictsorissueswerefound.

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Basedonthereasonablesimulation,theevaluatedproceduralstepcanperformedsuccessfullyper SectionD.9.f.TheOperationsstaffshowedsufficientknowledgeoftheactionbeingperformed.

OpenPlantDoors StepD.14.bcallsfortheopeningofdoorsasnecessarytopermitthefreeflowofwaterthroughthe plant.Thisactionisintendedtoallowforthefloodwaterstoevenlyfilltheplantandequalizethe pressureonbuildingwalls.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantity ofResources DurationofResources RequiredtoPerformTask 1)

RadiationProtectionbut couldincludeanyavailable onsitepersonnel Allavailablestaff minimum2teams of2(4staff)*

1.5hours

• OncetheOperationsControlCenterisstaffedall14RadiationProtectionStaffaremobilizedtothe plant.Thereisaminimumof2RadiationProtectionstaffonsiteatalltimes.

Asimplesimulationofopeningthedoorsinvolvedavisualinspectionofthereactorandturbine buildingsledbyanOperationsSupervisorpointingoutthedoorsinUnits2and3thatwouldbe opened in a flooding event. In addition, a Radiation Protection (Rad Pro) Supervisor was interviewed.OncenotifiedbytheOperationSupervisor,theRadProdepartmentwouldleadthis effortwithassistancefromanyavailableonsitestaff.TheRadProsupervisorinterviewedduringthe reasonablesimulationestimatedthatitwouldtake1.5hourstoopenandsecurealldoorsinthe plant.Theestimatewasbasedonpreviousperformanceofthetaskduringtheannualoutage.

Alldoorsappearedingoodconditionanddidnotshowsignsthattheycouldmalfunctioninaflood event. However, the procedure does not specify how the doors would be secured to remain opened.Ifthedoorsarenotsecuredcorrectly,theincomingfloodwatercouldforcethedoorsto closeandpreventthefreeflowofwaterbetweenrooms.Therewerenopotentialobstructions observedthatwouldpreventthedoorsfrombeingopenedandsecured,RadProandOperations staffwereknowledgeabletoproperlysecurethedoors,andtherearesufficientquantitiesofrope tosecurethedoors.

Based on the existing PMF hydrograph, the river levels will rise from elevation 517 ft MSL to elevation518ftMSLinapproximately1.5hoursandtherisingfloodwaterscouldmakeopening doorsmoredifficult.

Basedonthereasonablesimulation,theplantdoorsareinaconditionthatwouldallowthemtobe openedandsecuredasspecified.Openingofthedoorscould,however,beimpededduetothe risingwatersifitisinitiatedwhenriverlevelsreachelevation517ftMSL.

PlaceLocalIsolationCondenserSightglassintoService StepD.13.gcallsforplacingtheisolationcondensersightglassintoserviceandusingittomonitor thereactortemperaturetoestimatethecooldown/heatuprate.

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Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

EquipmentOperator 1

25minforbothunits

The Operations staff walked through the steps to place the isolation condenser sightglass into service and demonstrated how the procedure would be executed. The equipment was visually inspectedandtherewerenosignsofmaterialdegradationornonconformance.

Basedonthereasonablesimulation,theevaluatedproceduralstepcanperformedsuccessfullyper SectionsD.13.g.TheOperationsstaffshowedsufficientknowledgeoftheactionbeingperformed.

LossofSpentFuelPoolCooling StepD.14.icallsforaddingofmakeupwatertothespentfuelpoolusingthefiresystemwatervia hosestationslocatedadjacenttothespentfuelpool.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

EquipmentOperator 2

20minforbothunits

TheOperationsstaffwalkedthroughthestepsrequiredtofillthespentfuelpoolandidentifiedthe hosestationthatwouldbeusedtoaddwatertothespentfuelpool.Theinitialtimetosetupthe hoseandinitiateaddingwaterwouldrequireapproximately20minutesforbothunits.However, theOperationsstaffwouldthenberequiredtocontinuetomonitorspentfuelpoollevelsandadd waterasneeded.ThistaskwouldNOTrequirecontinuousstaffingbyOperations.

Basedonthereasonablesimulation,theevaluatedproceduralstepcanbeperformedsuccessfully per Sections D.14.i. The Operations staff showed sufficient knowledge of the action being performed.

ReactorScram DGP0203,ReactorScramisaprocedurethatisinitiatedwhenthewaterlevelsreachelevation509 ftMSL1.ThisprocedureisaStandardOperatingProcedurethathasbeenperformedinthepast and, therefore, a desktop review of the procedure was performed to evaluate the timing and resourcesneededfortheexecutionoftheprocedure.DGP0203istypicallyperformedinresponse toanautomaticreactorscramorwhenamanualscramisdesiredpriortoreachinganautomatic tripsetpoint.

1Theversionoftheprocedureevaluatedduringthewalkdown(rev.32)incorrectlystatedthatUnitShutdown(DGP 0201)ratherthanReactorScram(DGP0203)wouldbeusedtoshutdownbothunits.Theissuewasidentifiedprior tothewalkdown(AR01393890)andtheprocedurehasbeenrevisedaccordingly(rev.34).

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Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

ReactorOperator 2

5minutes

TheOperationstaffpresentedoperatorlogs,outageschedulesanddatatrendgraphstosupport thedeterminationwhetherReactorScram(DGP0203)canbeperformedinthecreditedtime.The procedurewillnotbechallengedbyfloodingconditionssinceitisperformedfromthecontrolroom beforefloodwatersinundatethesite.

Basedontheprovidedoperatorlogs,outageschedules,anddatatrendgraphs,ReactorScramcan beperformedinthecreditedtime.

ReactorVesselSlowFill DGP0202,ReactorVesselSlowFillisaprocedurethatisinitiatedfollowingaReactorScramorUnit Shutdown.ThisprocedureisaStandardOperatingProcedurethathasbeenperformedinthepast and, therefore, a desktop review of the procedure was performed to evaluate the timing and resources needed for the execution of the procedure. Reactor Vessel Slow Fill is a procedure implementedtoprovidecooldowntothereactorbyfloodingthereactorvessel.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

ReactorOperator 2

45minutes 2)

MechanicalMaintenance 1

TheOperationstaffpresentedoperatorlogs,outageschedulesanddatatrendgraphstosupport the determination of whether Reactor Vessel Slow Fill (DGP 0202) can be performed in the creditedtime.Theprocedurewillnotbechallengedbyfloodingconditionssinceitisperformed fromthecontrolroombeforefloodwatersinundatethesite.

Basedontheprovidedoperatorlogs,outageschedules,anddatatrendgraphs,ReactorVesselSlow Fillcanbeperformedinthecreditedtime.

UnitShutdown DGP0201,UnitShutdown,isaprocedurethatisinitiatedwhenriverlevelispredictedtoreach elevation509ftMSLwithin72hours(i.e.,theprocedurewouldbeinitiatedwhenStationpersonnel anticipate water level exceeding elevation 509 ft MSL any time within the next 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />). This procedureisaStandardOperatingProcedurethathasbeenperformedinthepastand,therefore,a desktopreviewoftheprocedurewasperformedtoevaluatethetimingandresourcesneededfor theexecutionoftheprocedure.

Manpowerresourcesrequiredforimplementationofthistaskareasfollowing:

TypeofResources RequiredQuantityof Resources DurationofResources RequiredtoPerformTask 1)

ReactorOperator 2

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TheOperationstaffpresentedoperatorlogs,outageschedulesanddatatrendgraphstosupport thedeterminationwhetherUnitShutdown(DGP0201)canbeperformedinthecreditedtime.The procedurewillnotbechallengedbyfloodingconditionssinceitisperformedfromthecontrolroom beforefloodwatersinundatethesite.

Basedontheprovidedoperatorlogs,outageschedules,anddatatrendgraphs,UnitShutdowncan beperformedinthecreditedtime.

DESKTOPEVALUATIONOFFLOODEMERGENCYPROCEDURE Following the completion of reasonable simulations and evaluation of individual procedural steps and actions, AMEC performed a desktop evaluation of the flood emergency procedure. During the desktop evaluation,timingandresourcedataobtainedduringthewalkdownwereanalyzedandcompiledtogether.

Themajoremphasisofthedesktopevaluationfocusedonansweringthefollowingquestions:

1. Arerequiredresourcesavailableduringoverlappingtasks?

2. Isthereasufficientfloodwarningavailabletoallowforsafereactorshutdownandstagingofthe dieseldrivenemergencymakeuppumpandtheassociatedcomponentsandconsumables?

3. Areconsumablesavailablefortheentiredurationsofthedesignbasisflood?

4. Canthefloodemergencyprocedurebeperformedundersimultaneousadverseweatherconditions orifthereisalossofoffsitepower?

AvailabilityofResources Actualstaffinglogs,EPDialogicsDatabase,andinterviewswithOperationsstaffwereusedtodetermine whethersufficientresourcesareavailabletoimplementtheentirefloodprocedure.Basedonthestaffing logs, the staffing at the Station is at its minimum levels during the weekend shifts and typically only Operationsstaffwouldbeavailabletoimmediatelyrespondtoanemergency.Theremainingstaffwould reporttotheplantbasedontheEmergencyClassificationLevelandfollowingtheprocedureforemergency response.ThelogsprovidedbytheStationindicatethat191staff,whichincludesMechanicalMaintenance, ElectricalMaintenance,InstrumentMaintenance,andRadiationProtectionstaff,isavailabletorespondto anemergencyandanadditional59offshiftOperationspersonnelareavailableforshortnoticecallout.To quantify the number of staff available for implementation of the procedure, the following assumptions wereused(basedoninterviewswithStationstaff):

1. Responsetimelessthanonehour-10%ofallavailablepersonnel.

2. Responsetimelessthanfourhours-additional70%(80%total)ofallavailablepersonnel.

3. Unabletorespondtoanemergencyduetoadverseweatherconditionsorduetootherreasons-20%ofallavailablepersonnel.

Asummaryofavailablestaffbasedontheabovementionedassumptionsandthestaffinglogsispresented inTable2below.

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Table2:SummaryofStaffAvailability

Ingeneral,allpersonnelrespondingtoafloodemergencywouldbeavailabletoassistwithimplementation ofthefloodemergencyprocedurewithoutbeingrequiredtoperformtasksrelatedtotheirusualjobduties.

Basedontheresultsofreasonablesimulations,alloverlappingtaskscouldbestaffedasneededusingthe availableresourcesorinitiatedafteradditionalstaffreportstothesite.Theonlytaskthatappearstohave limited resource availability within the first hour of declared flood emergency is the removal of service waterpumps.ThistaskisNOTrequiredfortheStationtorespondtorisingwaterleveland,therefore,NOT consideredacriticalpathitem.Table3providesasummaryofresourcesneededforimplementationofthe procedure,whichwerecrossreferencedwithavailableresources.

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Table3:ResourceUtilizationbasedonAvailability

7 7

0 47 18 29 1

0 1

7 1

6 4

8

-4 24 9

15 1

1 0

6 1

5 5

0 5

5 1

4 4

2 2

4 4

0 9

3 6

9 4

5 Response Time

<1hr

<4 hr Available Senior Reactor Operators Reactor Operators Equipment Operators Utilized Delta Mechanical Maintenance (craft)

Mechanical Maintenance (supervisors)

Electrical Maintenance (craft)

Electrical Maintenance (supervisors)

Utilized Delta Available ThefloodemergencyprocedurewouldbeinitiatedbytheShiftManager,whowouldcoordinatewithUnit Supervisorsanddeterminetheactionsneededtobeperformedimmediately.TheShiftManagerwouldalso determinewhetherconditionsofanEmergencyActionLevelaremetanddeclareEmergencyClassification Level, as appropriate. Depending on the Emergency Classification Level, an Emergency Response Organizationwouldlikelybeactivatedtocoordinateemergencyactivitiesonsite.

FloodWarning Asdescribedpreviously,thefloodwarningandthefloodwatcharetwocriticalcomponentsoftheflood emergencyprocedure.Thefloodemergencyprocedurereliesonanassumptionthatfloodwarningofriver levels exceeding elevation 509 ft MSL would be available to provide sufficient time to shutdown both reactorsusingstandardoperatingprocedureandimplementdependentactivities.However,itcouldnotbe readilyconcludedthatcurrentfloodwarning/watchproceduresprovideadequatefloodpredictionsforthe requiredmitigatingactions.Furthermore,currentriverforecastingtoolsarenotabletoaccuratelypredict exactlywhenelevation509ftMSLwillbeexceededattheDresdenintake.

Theproceduredoestakeintoconsiderationthepossibilitythatsufficientfloodwarningwillnotbeavailable andthatthefloodlevelscouldreachelevation509ftMSLwithoutsuchwarning.Underthisscenario,both unitswouldbeshutdownusingaReactorScramstandardoperatingprocedure,whichwouldallowthe reactorsystemstobecooledtothelowestpracticaltemperatureinamuchshorterperiodoftime.Since theprocedureacknowledgesthatasufficientfloodwarningmaynotavailable,itwasassumedthatthe subsequent procedural steps would also be initiated once river levels reach elevation 509 ft MSL. The criticaltimedurationtocompletethesetasksisbasedonthePMFhydrograph,whichpredictsthatriver levelswouldrisefromelevation509ftMSLto517ftMSLin7hours.Themajorityoftheactionscouldbe accomplished during this time; however, the construction of the sandbag berm would require longer durationandcouldpotentiallyaffecttheimplementationoftheprocedure.Notethattheconstructionof the sandbag berm is not required to ensure plant safety. The intent is to extend the availability of the IsolationCondensermakeuppumps.Thebermdoesnotneedtobecompletedupto519.5ftMSL.

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AvailabilityofConsumables The plant has sufficient supply of diesel fuel for operation of the makeup pump during the flood emergency.Thedieselfuelisstoredina4,000gallonabovegroundstoragetankandthetankisrefueled when the fuel level is below approximately 1,000 gallons. The fuel from the storage tank would be transferredinto55gallonbarrelsduringtheearlystagesofthefloodemergency.Oncethebarrelsarefilled withdieselfuel,theywouldbetransportedintothereactorbuildingandstagedatanelevationabovethe designbasis flood to ensure that diesel fuel is available for the entire duration of the storm. The flood emergency procedure states that four (4) 55gallon barrels would be staged in the reactor building; however, fullload fuel consumption estimates of 3.82 gallons per hour, suggest that 344 gallons (6.25 barrels)ofdieselfuelwouldberequiredforacontinuousoperationofthepump.Fillingthebarrelswith dieselfuelbeforethesiteisinundatedand/orlosesoffsitepowerwouldalsoensurethatthefuelcanbe transferredfromtheabovegroundstoragetank.

EvaluationofOverallEffectivenessoftheFloodEmergencyProcedure Theoveralleffectivenessofthefloodemergencyprocedureisdependentonaccuratefloodwarningand floodpredictionattheintakebay.Asdemonstratedduringthereasonablesimulation,theStationflood prediction capabilities are currently limited. Therefore, it could not be readily concluded that a flood warning,onwhichthefloodprocedurerelies,wouldbeadequatetoallowforasafeshutdownofboth rectors using the Unit Shutdown standard operating procedure. The more likely scenario is that both reactors would have to be shutdown using the Reactor Scram standard operating procedure once river levelsreachelevation509ftMSL.Asaresult,thetimeneededforimplementationoftheprocedurewould be reduced. Given the available resources, the installation of the sandbag berm could likely be accomplished in a shorter period of time to ensure that the isolation condenser makeup pumps are protectedwhenfloodlevelsrisetoplantgrade.Modificationstothesandbagbermconfigurationcouldalso beconsidered.

Thesubsequentproceduralstepscanbeaccomplishedefficiently(asdescribedearlierinthissection)and would support the overall implementation of the flood emergency procedure. The sequence of the proceduralstepsallowsforproperstaffingwithavailableresources.Giventhatthesubsequentprocedural steps are initiated at certain flood stages and the Station does not have a proper river gage, the Shift manager or the ERO would have to communicate with the Dresden Lock Master on a regular basis to determinewhencertaintasksneedtobeinitiated.Alternatively,riverlevelscouldbedeterminedusing computerpointE354,DischargeCanalWaterLeveland/orbymeasuringfloodwatersintheCribHouse usingatapemeasureandreferencedrawingB320CribHouseElevations.Oncetheriverlevelsreachplant grade,risingfloodlevelscouldbedeterminedusingtheplantgradeareferencepoint.

Adverse weather conditions (e.g., high winds, localized flooding, and freezing temperatures) can be expectedduringtheexecutionofthefloodemergencyprocedure.However,themajorityoftheprocedural stepswouldlikelynotbeaffectedbytheseconditions,sincetheyareperformedfromthecontrolroomor inside. For procedural steps performed outside, site conditions were evaluated to determine whether adverseweatherconditionscoulddelaythecompletionofthetask.Thetaskmostlikelytobeaffectedby adverse weather conditions is the construction of the sandbag berm. As described above, this task is a criticalpathitemthatshouldbeinitiatedearlyenoughduringresponsetoafloodtoensurethatitcanbe completedinthespecifiedtime.Earlyinitiationofthistaskwouldalsoprovideadditionalmarginofsafety, withrespecttoadverseweatherconditions.Allproceduralstepsweresimulatedassumingalossofoffsite Page34

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power.EmergencyDieselGeneratorswouldbeusedtopowertheequipmentandsystemsrequiredforthe executionoftheprocedureuptoafloodlevelof517ftMSL.

EVALUATIONOFINCORPORATEDPASSIVEBARRIERS Theexteriorbelowgradestructuresofreactorandturbinebuildingswereincludedonthewalkdownlistas incorporated passive barriers. The structures were evaluated for their effectiveness to prevent groundwateringressandwithstandhydrostaticloadsassociatedwithextremegroundwaterconditions.The penetrationsthroughtheexteriorwallswerealsoinspectedaspartofthevisualinspectionofthewallsand basementslabs.AnydegradedandnonconformingconditionswereenteredintotheCAPfordisposition.

The penetrations and the associated seals were, however, not treated as separate features and were recordedasobservationsassociatedwiththeWalkdownRecordFormforthewallorslabfeature.

Thefollowingacceptancecriteriawereusedforvisualinspectionsofbelowgradewallsandpenetrations seals:

Below-GradeWalls/BasementFloorSlabs Nosignsofdegradationofstructuralmembers.

Nosignificantsurfacecracks.

Nosignsofsignificantdegradation.

Nosignificantspalling,scaling,orcrackingofconcretesurfaces Penetrations/Seals:

Noindicationofdegradationthatwouldallowfloodwaterstopenetrateintothefloodprotected area.Conditionsthatshouldberecordedinclude(butarenotlimitedto)damage,undocumented openingsorholes(suchasthoseduetoabandonedequipment),etc.

Visiblepenetrationsaresealedwithnovisiblegaps.

Penetration sleeves, link seals, piping, and conduit should have an absence of corrosion on the exposedsteelsurface.

Conduitsealmaterialshouldhaveanabsenceofwaterstainsbelowthepenetrations.

Materialshouldappeartobeasindicatedinplantdocumentsandingenerallygoodcondition.

Basedonthevisualinspection,theconditionofbelowgradewallsUnit2/3ReactorBuildingsandUnit2/3 Turbine Buildings were considered to be acceptable. Overall, AMEC determined that the incorporated passive barriers would be able to perform their intended flood protection function and withstand the hydrostaticloadsassociatedwithextremegroundwaterconditionspertheCLB.However,duringthevisual inspection, AMEC observed wall segments with evidence of spalling, mineral deposition, and concrete degradationpossiblycausedbygroundwaterseepage.Inaddition,severalpenetrationsealsintheUnit2/3 EmergencyDieselGenerationRoomweredegradedandcouldnotbereadilyjudgedasacceptable.These conditionswereidentifiedontheFieldObservationReportsandreportedtoExelon.AMECdoesnotbelieve thatthesenonconformingconditionswouldcompromisethewallsabilitytowithstandhydrostaticloads andkeepthebelowgradeareasdry.

As part of the evaluation of incorporated passive barriers, AMEC performed a desktop evaluation of structuralandflooddrawingstoprovideareasonableassurancethatconduitsenteringthebuildingbelow Page35

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grade would not become a pathway for groundwater. AMEC has identified two electrical conduits in a 20inchsleevelocatedinthesoutheastcornerroomofUnitReactorBuilding.Thesetwoconduitswere inaccessibleforvisualinspectionduringthewalkdownduetoapullboxontheinsideofthebasementwall.

Thefacilitydrawingsindicatethatasealringwasinstalledinthecenterofthesleevetopreventpotential groundwater ingress and the conduits were sealed as well. In addition, there was no indication of past groundwater ingress below the penetration. No other belowgrade electrical conduits were identified duringthewalkdowns.

Thefloodemergencyproceduredoesnotspecificallystatemodesofoperationforwhichtheprocedureis applicable.Forthisevaluationfullpowermodeoperationwasconsideredthemostcriticalplantfailure mode,whichwouldrequirethehighestnumberofresourcesandthelongestduration.Duringothermodes ofoperation,e.g.refuelingoutage,additionalresourceswouldbeavailabletoassistwithimplementation oftheprocedure.

SITETOPOGRAPHY DetaileddescriptionofsitetopographyusedfortheLIPanalysiswasnotprovidedintheSEPreportorother CLBdocuments.TheSEPreportonlydescribedthesizeofdrainageareas,averageManningnvalues,and an average slope between the buildings and the drainage channel. Dimensions of the channel or other detailedmeasurementswerenotprovided.Theavailablefreeboardaroundthebuildingswasbasedonthe differencebetweenthePMFdischargedepthandelevationsofnonwatertightopeningsinwallsofsafety relatedstructures(517.5ftMSL),whichhavenotchangedsincethecompletionoftheLIPanalysis.The plantgradeelevation(517ftMSL)usedintheanalysisisconsistentwithexistinggradeelevation.

e. Requested Information Item 2(e) - Implementation of Walkdown Process Presentinformationrelatedtotheimplementationofthewalkdownprocess(e.g.,detailsofselectionof the walkdown team and procedures) using the documentation template discussed in Requested Information Item 1.j [in Enclosure 4 of the March 12, 2012, 50.54(f) letter], including actions taken in responsetothepeerreview.

Themembersofthewalkdownteamwerecarefullyselectedtoensurethattheteamincludesindividuals who are experienced in conducting visual inspections of plant structures, systems and components and flood protection features. The team for Dresden Station included two Water Resources Engineers, an ElectricalEngineer,andaStructuralEngineer.Bothwaterresourcesengineersarefloodingspecialistsand havesignificantexperiencewithinspectionsandevaluationsoffloodprotectionfeatures.Theremaining twoengineersareemployeesofAMECsNuclearServicesdivisionandareexperiencedinconductingvisual inspectionofplantSSCs.

EachmemberoftheteamcompletedExelonsWalkdownTraining,NuclearGenerationEmployeeTraining (NGET),andNANTeLsgenericverificationwalkdownsofplantfloodprotectionfeaturescourse,including passingtheNANTeLexam.Inpreparationforthewalkdown,theteammembersbecameknowledgeableof thesitescurrentlicensingbasisandoperatingproceduresbythoroughlyreviewingthemduringthefirst phase of the project. Where specific knowledge was necessary to inspect a flood protection feature/procedure, at least one member of the walkdown team had the ability to determine if the conditionofthefeature/procedureneededtobeenteredintotheCAP.

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Theapproachusedforimplementationofthewalkdownprocesswastobreakdowntheevaluationofthe procedures and features based on staffs individual experience and expertise. All team members had a thoroughunderstandingoftheproceduresandtheactionsrequiredtobeaccomplishedtomitigatethe design basis flood; however, AMECs staff with relevant nuclear inspection experience focused predominatelyonnuclearspecifictasks(e.g.,StandardOperatingProcedures)andonassessingmajorityof control room actions. The flooding specialists focused predominately on evaluation of flood prediction warningsandonvisualinspectionofpenetrationsandbelowgradewalls/slabs.Theremainingreasonable simulationsweredividedbyindividualswithspecificknowledgeoftheevaluatedtask/action.

Aprejobbriefwasperformedatthebeginningofeachworkday.Thesubjectsdiscussedintheprejob briefs included but were not limited to positive component verification, inspection methodology, acceptance criteria, field documentation requirements, reporting degraded conditions and previous walkdown lessons learned. A highradiation prejob brief was performed with the walkdown team and radiationprotectionpersonnel,asnecessary.Subjectsdiscussedinhighradiationprejobbriefsincluded butwerenotlimitedtotasksrequiredtocompletethejob,timerequiredtocompletethetasks,doserate surveys,maximumdoseratesandtotalallowabledose.

Aladderandacameraonastickwereusedtoperformvisualinspectionoffloodprotectionfeaturesthat werenotaccessiblefromtheplantfloor.

Observations captured during the walkdowns were documented using the Walkdown Inspection Tool SmartphoneapplicationandusingthepapercopiesoftheFieldObservationReports.Twomembersofthe walkdownteamcompletedthevisualinspectionstocomplywiththepeerreviewrequirements.Walkdown RecordFormsprovidedinAppendixBofNEI1207(Rev0A)werecompletedbasedontheobservations made during the visual inspection. Degraded or nonconforming conditions were documented using a camera.CompletedWalkdownRecordFormswerepeerreviewedandsignedasrequired.

Adailyprojectreportwasgeneratedattheendofeachworkdaydocumentingthefollowing:

IndustrialSafety/FirstAid RadiologicalInformation ALARAInformation ProductionPerformance DeficienciesIdentified OperabilityIssuesIdentified GeneralProblems IRs ItemsRequiringFurtherReview LessonsLearned ObservationsnotimmediatelyjudgedasacceptablewerereportedtoExelonpersonnelimmediatelyand enteredintheCAP,asnecessary.

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f. Requested Information Item 2(f) - Findings and Corrective Actions Taken/Planned Resultsofthewalkdownincludingkeyfindingsandidentifieddegraded,nonconforming,orunanalyzed conditions.Includeadetaileddescriptionoftheactionstakenorplannedtoaddresstheseconditionsusing theguidanceinRegulatoryIssuesSummary200520,Rev1,RevisiontoNRCInspectionManualPart9900 TechnicalGuidance,OperabilityConditionsAdversetoQualityorSafety,includingenteringthecondition inthecorrectiveactionprogram.

ObservationsnotImmediatelyJudgedasAcceptable BelowGradeWallsandBasementSlabs Duringthefloodingwalkdown,AMECdidnotidentifydegradedornonconformingconditionsofbelow gradebasementwallsthatwouldpreventthewallsfromperformingtheirfloodprotectionfunction. As such, the overall condition of the basement walls was considered acceptable; however, several wall segments with evidence of spalling and concrete degradation, possibly resulting from groundwater seepage,wereobservedduringthewalkdown(asnotedonFieldObservationReports).Theseconditions were previously identified and entered in the CAP (AR numbers 1290630, 1054344, 1068074, 1070652, 1108699,1249329,1249834,and1376704).Inaddition,twopenetrationsealsinthe2/3EmergencyDiesel Generator (EDG) Room could not be readily judged as acceptable. However, these conditions were previouslyidentifiedduringaStructuresMonitoringWalkdownperERMW450anddispositionedthrough theCAPasacceptable(AR01131053).

Noneoftheindividualfloodprotectionfeatures(belowgradewallsorbasementslabs)wereconsidered inaccessible.However,threepenetrations/sealswerenotvisuallyinspectedduringthewalkdownandare considered inaccessible. One penetration is a 20inch sleeve with two electrical conduits. Based on the review of facility drawings, a seal ring was installed in the center of the sleeve to prevent potential groundwater ingress and both conduits daylight at aboveground junction boxes at the contaminated condensatestoragetanks.Inaddition,therewasnoevidenceofleakagebelowthepenetrationsleeve.

Therefore,itisreasonabletoconcludethattheconditionofthepenetrationsealisacceptableandwould not compromise the belowgrade walls ability to function as a flood protection barrier. In addition, conduitsthemselveswouldnotbecomepathwayforgroundwatersincetheydonotleadtoanymanholes anddaylightabovetheground.

Two additional inaccessible penetrations are located in the Unit 2 CCSW Pump Area (Vault) and Unit 3 CCSWPumpArea(Vault),respectively.Thepenetrationscouldnotbevisuallyinspectedwithoutbreaking theplaneduetotheconfigurationofthepipe.Therewasnoindicationofgroundwateringressbelowthe penetration sleeve. A desktop evaluation was conducted to determine whether a penetration seal is present.However,theinformationprovidedinthedrawingsiscontradictory.Forinstance,theFloodBarrier Drawings(FL8andFL24)indicatethatbothpenetrationsleeveshaveasealandrefertoM151andM476 drawingsforsealtypebutthelatterdrawingsindicatethatthepenetrationsleeveswerenotequippedwith seals.ThisdiscrepancywasresolvedthroughAR00127680.Inaddition,theabsenceofpastandcurrent evidence of groundwater seepage below the penetration indicates that the sleeves would not become pathway for groundwater. The penetrations are also inspected on a regular basis during the Structures MonitoringWalkdown.Theoveralleffectivenessofthebasementwalltoprovidefloodprotectionagainst groundwateringressshouldnotbeaffected.

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FloodEmergencyProcedure Basedonthereasonablesimulationsanddesktopevaluationofthefloodemergencyprocedureandthe associated operating procedures, the walkdown team determined that the Station has the required resources to effectively implement the minimum critical path actions required to safely shutdown the reactorusingaReactorScramstandardoperatingprocedureandprovidealternativecoolingofthereactor core during a flood emergency. AMEC has, however, identified several procedural steps that rely on knowledgebasedactionsandlacksufficientspecificity,relyonfloodwarningthatmaynotbeavailable,or cannot be implemented as written due to the insufficient flood warning. A summary of these items is providedbelow.

1. ResourcesarenotavailabletoaccuratelypredictriverlevelsattheDresdenintake.However,the flood emergency procedure is entered following flood forecast by NWS, notification from TransmissionSystemOperatorpredictingrainfallof2inchesin6hours,orriverlevel506.5ft MSLattheCribHouse.Furthermore,itisreasonabletoassumethatarainfallofthedesignbasis magnitudewouldbepredictedinadvance,whichwouldallowthesitetoinitiatefloodprotection measures based on a rainfall forecast. But it is possible that the normal shutdown per Unit Shutdown (DGP 0201) may not be completed prior to the flood waters elevation 509 ft MSL.

ShutdownperReactorScram(DGP0203)wouldthenhavetobeinitiatedoncefloodwatersreach elevation509ftMSLtoreducedecayheattothelowestpossiblelevelandallowfortheuseof isolationcondensersmakeuppumpsandthedieseldrivenemergencymakeuppumpforreactor cooling.Inaddition,theversionoftheprocedureevaluatedduringthewalkdown(rev.32)didnot statethatReactorScramwouldbeusedtoshutdownbothunits.TheissuewasaddressedbyAR 01393890andtheprocedurehasbeenrevisedaccordingly(rev.34).

2. Thefloodemergencyprocedureaddressesremovaloftwo(2)ServiceWaterPump(SWP)Motorsto aidinrecoveryafterthefloodwatersrecede.However,motorremovalisNOTrequiredforthe Station to respond to rising water level, safely shutdown both reactors, and maintain alternate coolingduringthedurationoftheflood.Giventheindefinitefloodwarningandtheimportanceof maintainingequipmentredundancyontheServiceWaterSystem,itispossiblethattheremovalof twoSWPMotorswouldbeinitiatedonlyonceriverlevelsreachelevation509ftMSL.Underthis scenario,theElectricalMaintenancestaffwouldnothavesufficienttimetomovethemotorstothe upperlevelbeforefloodwatersinundatethelowerlevelsofthecribhouse.ThePMFhydrograph estimatesthatthefloodlevelswouldrisefromelevation509toelevation513in3hoursandthe estimatedtimetomovethemotorstotheupperlevelisapproximately8hours(9hoursand11 hours,respectively,tomovebothmotorstotheTurbineBuilding).Inaddition,thistaskappearsto havelimitedresourceavailabilitywithinthefirsthourofdeclaredfloodemergency.Removaloftwo SWPmotorsrequires9ElectricalMaintenancestaffwhileonly5staffwouldbeavailabletoreport todutywithinthefirsthour.WhilethistaskisNOTcriticalforensuringthatthereactorissafely shutdownandcoolingofthereactorismaintained,theinabilitytoperformthetaskmayaffectthe recoverystageandrequireadditionalresourcestobeemployed(e.g.,continuouscoolingusingthe makeuppump).TheissuewasaddressedbyAR01393890andprocedurerevisionisinprocess.

3. Construction of the sandbag berm is initiated when the river levels are predicted to exceed elevation509ftMSL.Asstatedabove,resourcesarenotavailabletoaccuratelypredictriverlevels attheDresdenintakeinadvance.However,thefloodemergencyprocedureisenteredfollowing floodforecastbyNWS,notificationfromBulkPowerOperationspredictingrainfallof2inchesin6 hours,orriverlevel506.5ftMSLattheCribHouse.Furthermore,itisreasonabletoassumethata Page39

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rainfallofthedesignbasismagnitudewouldbepredictedinadvance,whichwouldallowthesiteto initiate flood protection measures based on a rainfall forecast. Since the minimum time to construct the sandbag berm is 8.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, there is a possibility that the berm would be not be constructedintimebeforefloodwatersreachtheplantgradeifconstructiondoesnotbeginbefore riverlevelsreachelevation509ftMSL.Risingfloodwaterscouldthenimpacttheoperationofthe isolationcondensermakeuppumps.However,initiationofsandbaggingpreparationswhenthe flood emergency procedure is entered due to weather forecast will aid the Station in timely construction of the sandbag berm. The issue was addressed by AR 01393890 and procedure revisionisinprocess.

4. Theprocedurestatesthatfour(4)55gallonbarrelsofdieselfuelstagedinthereactorbuildingwill conservativelyprovidea2daysupplyofdieselfuelfortheemergencymakeuppump.However, based on the PMF hydrograph the emergency makeup pump would have to be used for a minimumof78hoursbeforefloodlevelsrecedetoelevation509ftMSLandadditional12hours beforeservicewaterpumpsareallowedtobereinstalled.Basedonthefullloadfuelconsumption of3.82gallonsperhour,344gallons(6.25barrels)ofdieselfuelwouldberequiredforacontinuous operationofthepump.TheStationhasadditionaldieselfuelbarrelsavailableforuseduringflood emergency.TheissuewasaddressedbyAR01422791andprocedurerevisionisinprocess.

5. The opening of plant doors is initiated when flood water reach elevation 517 ft MSL. However, based on the existing PMF hydrograph flood waters could reach elevation 518 ft MSL in approximately1.5hours.Asaresult,risingfloodwaterscouldmakeopeningdoorsmoredifficult.

TheissuewasaddressedbyAR01422791andprocedurerevisionisinprocess.

6. TheprocedurerequiresthatalltransformersandMCCsonelevation517ftMSLbedeenergized whentheriverlevelreacheselevation517ftMSL.WhiletheOperationsstaffdemonstratedthe knowledgeoftheproceduralstepandtheabilitytosuccessfullyperformtheproceduralstepas written,theproceduralstepdoesnotclearlystatewhichBusshouldbedeenergizeddownordoes notexplicitlystatewhichtransformersandMCCsonelevation517ftMSLareimpacted.Theissue wasaddressedbyAR01422791andprocedurerevisionisinprocess.

7. Theprocedurestates(D.13.a,D.13.b)thatthelevelinabovegroundwaterstoragetankswillbe raisedtoalevelatleast10feetabovethegroundandthelevelinbelowgroundwaterstorage tankswillbecheckedandthestoragetankswillbefilledwithwater,ifneeded,whenriverlevels arepredictedtoexceedelevation517ftMSL.WhiletheOperationsstaffwasabletosuccessfully simulatetheproceduralstepaswritten,theproceduredoesnotspecificallystatewhichtanksthe actionsshouldbeperformedon.TheissuewasaddressedbyAR01422791andprocedurerevision isinprocess.

ObservationsDesignatedthroughCAPasDeficient None ObservationsAwaitingFinalDispositioninCAP AllobservationsnotreadilyjudgedasacceptablearecurrentlyawaitingfinaldispositionintheCAP.

FeaturesinRestrictedAccessAreas None Page40

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FeaturesinInaccessibleAreas Three(3)penetrationswereconsideredinaccessibleforvisualinspection.Reasonableassurancethatthe componentscanprovidetheirintendedfunctionwasprovidedbyabsenceofpastandcurrentevidenceof groundwaterseepagebelowthepenetrationandbyreviewofavailabledrawings.

ActionsTakenorPlannedtoAddressDeficiencies None

g. Requested Information Item 2(g) - Cliff -Edge Effects and Available Physical Margin Documentanycliffedgeeffectsidentifiedandtheassociatedbasis.Indicatethosethatwereenteredinto the corrective action program. Also include a detailed description of the actions taken or planned to addresstheseeffects.

CliffedgeeffectsweredefinedintheNTTFReport(Reference5)asthesafetyconsequencesofaflooding eventmayincreasesharplywithasmallincreaseinthefloodinglevel.AsindicatedinSections3.12ofNEI 1207 (Reference 2), the NRC is no longer expecting the Recommendation 2.3: Flooding Walkdowns to includeanevaluationofcliffedgeeffects.TheNRCisnowdifferentiatingbetweencliffedgeeffects,which areaddressedinEnclosure2ofReference3,andAvailablePhysicalMargin(APM).

As indicated in Sections 3.13 of NEI 1207 (Reference 2), APM describes the flood margin available for applicablefloodprotectionfeaturesatasite(notallfloodprotectionfeatureshaveAPMs).TheAPMfor eachapplicablefloodprotectionfeatureisthedifferencebetweenlicensingbasisfloodheightandtheflood heightatwhichwatercouldaffectanSSCimportanttosafety.

APMinformationwascollectedduringthewalkdownstoprimarilysupporttheresponsetoEnclosure2of Reference3and,assuch,isnotincludedinthisreport.APMdeterminationsdidnotinvolvecalculatingcliff edgeeffects(i.e.thesafetyconsequences).DuringtheIntegratedAssessment(seeEnclosure2ofReference 3), the cliffedge effects and the associated safety risks will be evaluated using the APMs and other information,suchasthespecificSSCsthataresubjectedtofloodingandthepotentialavailabilityofother systems to mitigate the risk. Furthermore, observations of small margin and significant consequences wereenteredintotheCAPforfurtherevaluation.

SincethewalkdownswerecompletedpriortothefinalresolutionofFAQ006(September13,2012),APM informationwascollectedanddocumentedontheWalkdownRecordFormusingtheoldapproach;that is,asimplemeasurementofthedifferencebetweenthelicensingbasisfloodheightandthefloodheightat whichwatercouldaffectanSSCimportanttosafety.

h. Requested Information Item 2(h) - Planned/NewlyInstalled Flood Protection Enhancements Describe any other planned or newly installed flood protection systems or flood mitigation measures including flood barriers that further enhance the flood protection. Identify results and any subsequent actionstakeninresponsetothepeerreview.

TheStationiscurrentlyconsideringchangesthatwouldstreamlinetheexistingfloodemergencyprocedure, reducetheneedformanpowerresourcestoimplementtheprocedure,andenhancefloodprotection.The followingitemsarebeingconsidered:

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1. Obtainingafloatingdockthatwouldbeusedforstagingoftheemergencydieselmakeuppump, reducingtheneedforraisingandloweringofthepumpduringaflood.Duringaflood,thefloating dockwouldbestagedandsecuredatthecenteroftheUnit2ReactorBuildingequipmenthatch.

ThisdockhasbeenprocuredbytheStationandaprocedurerevisionisinprocess.

2. Floodproofingofisolationcondensermakeuppumpsbuildingaccessdoorstoeliminatetheneed forconstructionofthesandbagberm.

3. Floodproofingofadditionalbuildingaccessdoorstomaintainequipmentavailabilityandpersonnel safetyaslongaspossibleinotherlocationssuchasthereactorbuildings.

4. InitiationofsandbagberminstallationbasedonacombinationofactualriverlevelsattheDresden intakeandfloodpredictionsfromthetwoclosestrivergaugeswithfloodforecastingcapabilities (KankakeeRiveratWilmingtonandIllinoisRiveratMorris).

5. Developmentofamethodtoprovideadditionalwaterintothebelowgradeareasbeingusedby thedieseldrivenemergencymakeuppumponcefloodwatersrecedebelowelevation518ftMSL.

BasedonaninterviewwiththeOperationsSupportManager,theStationcouldutilizeFLEXpumps todivertwaterfromcoolingcanalsintothereactorbuildingbasementorthefireheadercouldbe reconfiguredtodivertwaterfromthecanaltothefiresuppressionsystemtobeusedformakeup coolingwater.Thiswouldallowforflexibilityduringrecoveryeffortsbymaintainingthecontinued availabilityofthedieseldrivenemergencymakeuppump.

5. CONCLUSIONS The flooding walkdown at Dresden Station was conducted between August 8 and August 16, 2012 and includedavisualinspectionofbelowgradewallsandtheassociatedpenetrations,avisualinspectionof basementslabs,andreasonablesimulationsofthefloodemergencyprocedureandtheassociatedtasks andprocedures.

AsummaryofthefloodingwalkdownresultsisprovidedinTable4throughTable9.Thebelowgradewalls andslabswereinspectedandarrangedbyareasorroomsforatotaloffifteen(15)features.Associated penetrations/seals were visually inspected during the walkdown; however, they were not considered individual flood protection features and only penetrations/seals not readily judged as acceptable or inaccessiblepenetrations/sealswerelistedinTable7andTable9,respectively.

Nineteen (19) reasonable simulations of the flood emergency procedure and the associated procedures (including standard shutdown procedures) were performed to ensure that they can be performed as specifiedandprotectthereactorfromcoredamageduringfloodingconditions.Basedontheevaluationof reasonablesimulationsandreviewofoperatorlogs,thecriticalpathitemsoffloodemergencyprocedure can be implemented to ensure that both units are safely shutdown and reactor cooling is provided to removedecayheat.Duringtheevaluationitwasdeterminedthatresourcesarenotavailabletoaccurately predictriverlevelsattheDresdenintakeinadvance.Assumingonlyashortfloodwarningisavailable,the constructionofthesandbagmaynotbeimplementedintimeorusingtheavailableresources.However, initiationofsandbaggingpreparationsatanearlierpointintheFloodEmergencyProcedureduetoweather forecastwillaidtheStationintimelyconstructionofthesandbagbermandprovideanadditionalmarginof safety.

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Table4:Summary-FeaturesIncludedintheWalkdownScope FeatureType TotalNumber Passive-Incorporated 15 Passive-Temporary 0

Active-Incorporated 0

Active-Temporary 0

Table5:ReasonableSimulations Description Purpose 1

FloodWarning&FloodWatch Providesufficientfloodwarningtosafely shutdownbothreactorsandimplements dependentfloodemergencyactions.

2 DieseldrivenEmergencyMakeupPump (movingandstaging)

Providemakeupcoolingwaterforthe isolationcondenserswhenpermanently installedequipmentisinoperable.

3 ConstructionofSandbagBermaround theIsolationCondenserMakeupPumps Building Designedtoprotecttheisolationcondensers makeuppumpbuildinguntilfloodwaters reachhighenoughtoprovidesuctionforthe emergencydieseldrivenmakeuppump.

4 DeenergizeMCCs Disconnectallelectricalequipmentpriorto floodwaterreachingplantgradeelevation.

5 ManualOperationoftheIsolation Condensers Providecoolingofthereactorsystemswhen othersystemsareinoperableandisolation condensershavetomanuallyoperated(e.g.,

duringlossofoffsiteandbackupbattery power).

6 PreparefortheRemovalofSWPMotors andSecure23SWPs ProtectSWPmotorsforrecoveryphase whenSWPwillbeusedforcoolingofreactor systems.

7 RaiseWaterStorageTankLevel&

Check/FillBelowgroundWaterStorage Tanks Preventthetanksfrombecomingbuoyant.

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Description Purpose 8

RestoreReactorVesseltoNormalWater Level Restorenormalwaterlevelsbeforereactor coolingistransferredtotheisolation condensers.

9 SealDieselOilStorageTankVents Preventintroductionofriverwaterinto dieseloilstoragetanks.

10 SecureIsolationCondenserPumps Takespumpmotorsofflineoncethediesel drivenemergencypumpisusedtoprovide makeuptotheisolationcondensers.

11 Unit1-DFPControlSwitchOffSecure Equipment,SecurePowertoPC5 Preventautomaticstartonlossofpower.

12 Unit1PostIncidentPump ProvideflowpathintotheUnit1sphereto equalizepressuresonspherewalls.

13 Close/OpenFireProtectionSystem Valves

Allowtheconnectionoftheemergency dieseldrivenmakeuppumptothefire protectionsystemandtheuseofriverwater asmakeupwatersource.

14 OpenPlantDoors Allowfreeflowofwaterthroughplantto equalizehydrostaticpressureandprevent collapseofexteriorwalls.

15 PlaceLocalIsolationCondenserSightglass intoService MonitorIsolationCondenserlevelto maintainaheatsink.

16 LossofSpentFuelPoolCooling Providemakeupwaterforspentfuelpools whensafetyrelatedequipmentis inoperable.

17 ReactorScram Fastshutdownofthereactorwhensufficient floodwarningisnotavailable.

18 ReactorVesselSlowFill Coolreactorsystemstolowestpractical temperatureasquicklyaspossible.

19 UnitShutdown Normalshutdownprocedureincaseofa floodemergencywhensufficientflood warningisavailable.

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Table6:ListofFeaturesImmediatelyJudgedasAcceptable FeatureID#

Description Passive/Active Incorporated/Temporary 1

D02RB476W001FW DO2RB476W002FW Eastandsouthbelowgrade wallsofU2southeastcorner room IncorporatedPassive 2

RB2TORUS Eastandsouthbelowgrade wallsofU2torus IncorporatedPassive 3

D02RB476W005FW SouthbelowgradewallofU2 southwestcornerroom IncorporatedPassive 4

D23RB476W006FW D23RB476W007FW D23RB476W008FW East,south,andwestbelow gradewallsofU2/3HPCI Room IncorporatedPassive 5

RB3TORUS Westandsouthbelowgrade wallsofU3torus IncorporatedPassive 6

D03RB476W002FW DO3RB476W001FW Westandsouthbelowgrade wallsofU3southwestcorner room IncorporatedPassive 7

D02TB469W001FW D02TB469W002FW D02TB469W003FW D02TB469W004FW D02TB469W005FW D02TB469W006FW BelowgradewallsofU2 CondensateBoosterPump Area IncorporatedPassive 8

D02TB495W007FW D02TB495W008FW D02TB495W009FW D02TB495W010FW D02TB495W014FW D02TB495W015FW D02TB495W016FW D02TB495W017FW D02TB495W018FW BelowgradewallsofU2 CCSWPumpArea IncorporatedPassive Page45

NTTFRecommendation2.3(Walkdowns):Flooding ExelonCorporation November20,2012 Revision0

FeatureID#

Description Passive/Active Incorporated/Temporary 9

D03TB469W001FW D03TB469W002FW D03TB469W003FW D03TB469W004FW D03TB469W005FW D03TB469W006FW BelowgradewallsofU3 CondensateBoosterPump Area IncorporatedPassive 10 D03TB495W007FW D03TB495W008FW D03TB495W009FW D03TB495W010FW D03TB495W014FW D03TB495W015FW D03TB495W016FW D03TB495W017FW D03TB495W018FW BelowgradewallsofU3 CCSWPumpArea IncorporatedPassive 11 D23EDG BelowgradewallsofU2/3 EmergencyDieselGenerator Room IncorporatedPassive 12 D02RBSLAB FloorslabsofU2Reactor Building IncorporatedPassive 13 D03RBSLAB FloorslabsofU3Reactor Building IncorporatedPassive 14 D02TBSLAB FloorslabsofU2Turbine Building IncorporatedPassive 15 D03TBSLAB FloorslabsofU3Turbine Building IncorporatedPassive

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Table7:ListofFeaturesNotImmediatelyJudgedasAcceptable FeatureID#

Description Observation Component Operability Resolution 1

15PEN (Penetration

1. 2,drawingFL 34) 20insleeve w/16in cappedpipe Penetrationseal showedsignsofwater seepage,bacterial growth,andmaterial degradation.

Yes-previously documented inAR 01131053 Basedonthe walkdown associatedwith AR1131053, plantpersonnel determinedthat thefloodseals areacceptable andcapableof performingtheir intended function.

2 17PEN (Penetration

1. 4,drawingFL 34) 20insleeve w/16in cappedpipe Penetrationseal showedsignsofwater seepage,bacterial growth,andmaterial degradation.

Yes-previously documented inAR 01131053 Basedonthe walkdown associatedwith AR1131053, plantpersonnel determinedthat thefloodseals areacceptable andcapableof performingtheir intended function.

3 DOA001004, Floods(W4)

Rev.33 Flood Emergency Procedure Severalprocedural steps,asdescribedin Section4f N/A-documented inAR 01422791and AR01422880 Procedure revisionin progressto enhancestation responseto issuesidentified inthisreport

Table8:ListofFeaturesinRestrictedAccessAreas FeatureID#

Description Reason Resolution N/A N/A N/A N/A N/A

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Table9:ListofFeaturesinInaccessibleAreas FeatureID#

Description Reason Resolution 1

3PEN(Penetration#1, drawingFL8)

12insleeve Sealnotvisible duetopipe connection.

Wouldrequire intrusive methodsto inspect.

Reasonableassurancethat thecomponentcan provideitsintended functionwasprovidedby absenceofpastand currentevidenceof groundwaterseepage belowthepenetration.

2 6PEN(Penetration#1, drawingFL24) 16insleevew/

6inhypochlorite pipe.

Sealnotvisible duetopipe configuration andelbow connection.

Wouldrequire intrusive methodsto inspect.

Reasonableassurancethat thecomponentcan provideitsintended functionwasprovidedby absenceofpastand currentevidenceof groundwaterseepage belowthepenetration.

3 18PEN(Penetration

1. 1,drawingFL39) 20insleevew/2 electrical conduits Coveredwithpull box.

Reasonableassurancethat thecomponentcan provideitsintended functionwasprovidedby absenceofpastand currentevidenceof groundwaterseepage belowthepenetration andbyreviewof drawings.

6. REFERENCES

1. ExelonLettertoU.S.NuclearRegulatoryCommission.ExelonGenerationCompany,LLCs90Day ResponsetoMarch12,2012RequestforInformationPursuanttoTitle10oftheCodeofFederal Regulations50.54(f)RegardingRecommendations2.1and2.3,oftheNearTermTaskForceReview ofInsightsfromtheFukushimaDaiichiAccident(Flooding).June11,2012.

2. Nuclear Energy Institute (NEI), Report 1207 (Rev 0A). Guidelines for Performing Verification WalkdownsofPlantProtectionFeatures.May2012[NRCendorsedMay31,2012;updatedandre issuedJune18,2012].

Page48

NTTFRecommendation2.3(Walkdowns):Flooding ExelonCorporation November20,2012 Revision0

Page49

3. U.S.NuclearRegulatoryCommission.LettertoLicensees.RequestforInformationPursuanttoTitle 10oftheCodeofFederalRegulations50.54(f)RegardingRecommendations2.1,2.3,and9.3ofthe NearTermTaskForceReviewofInsightsfromtheFukushimaDaiichiAccident.March12,2012.

4. U.S. Nuclear Regulatory Commission. Demonstrating the Feasibility and Reliability of Operator ManualActionsinResponsetoFire.NUREG1852.October2007.

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6. U.S.NuclearRegulatoryCommission.OperabilityDeterminations&FunctionalityAssessmentsfor ResolutionofDegradedorNonconformingConditionsAdversetoQualityorSafety.NRCInspection Manual. Part 9900: Technical Guidance. Regulatory Issues Summary 200520, Revisions 1.

September26,2005.

7. U.S. Nuclear Regulatory Commission. Followup to the Fukushima Daiichi Nuclear Station Fuel Damage Event. Inspection Manual. Temporary Instruction 2515/183. ML113220407. November 2011.

8. U.S.NuclearRegulatoryCommission.EvaluateReadinesstoCopewithExternalFlooding.Inspection Procedures.Attachment71111.01.AdverseWeatherProtection.Section02.04.

9. UpdatedFinalSafetyAnalysisReportforDresdenGeneratingStation,Rev.7,June2007,Sections 2.3,2.4,and3.4.

10. U.S.NuclearRegulatoryCommission.Dresden2NuclearGeneratingStation,SafetyEvaluationof Hydrology SEP Topics II3.A, II3.B, II3.B.1 and II3.C, Enclosure 1 - Safety Evaluation Report, -TechnicalEvaluationReport.June21,1982.

11. AMECEnvironment&Infrastructure.IndependentFloodRiskAssessmentfollowingtheFukushima DaiichiNuclearPowerStationEvents.August23,2011.

12. DOA001004,Floods(W4),Rev.32,Rev.33,andRev.34

13. DGP0201,NormalUnitShutdown

14. DGP0202,VesselSlowFill

15. DGP0203,ReactorScram

16. DOP130003,ManualOperationofIsolationCondenser

17. DOS130004,OperationoftheIsolationCondenserExternalFloodEmergencyMakeupPump

18. DOP130005IsolationCondenserLevelMonitoringUsingtheLocalSightGlass

19. ERAA450,StructuresMonitoring,Rev.1