RS-12-160, Co, Llc’S 180-day Response to NRC Request for Information Pursuant to 10CFR50.54(f) the Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident

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

ML12332A378
Person / Time
Site:	Braidwood
Issue date:	11/27/2012
From:	Kaegi G Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-12-160
Download: ML12332A378 (27)

Text

10 CFR 50.54(f)

RS-12-160 November 27, 2012 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, MD 20852 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457

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 Braidwood Station, Units 1 and 2 180-day response to Reference 1 for Flooding Recommendation 2.3.

Conditions identified during the walkdowns were documented and entered into the corrective action program. to this letter provides the requested information for Braidwood Station Units 1 and 2.

This letter contains new regulatory commitments, which are identified in Enclosure 2.

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, 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 Braidwood Station, Units 1 and 2

2. Summary of Regulatory Commitments cc:

Director, Office of Nuclear Reactor Regulation Regional Administrator - NRC Region III NRC Senior Resident Inspector - Braidwood Units 1 and 2 NRC Project Manager, NRR - Braidwood Units 1 and 2 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 Braidwood Station, Units 1 and 2 180-day response to Reference 1 for Flooding Recommendation 2.3.

Conditions identified during the walkdowns were documented and entered into the corrective action program. to this letter provides the requested information for Braidwood Station Units 1 and

2.

This letter contains new regulatory commitments, which are identified in Enclosure 2.

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, Ar&p° 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 Braidwood Station, Units 1 and 2

2. Summary of Regulatory Commitments cc:

Director, Office of Nuclear Reactor Regulation Regional Administrator - NRC Region III NRC Senior Resident Inspector - Braidwood Units 1 and 2 NRC Project Manager, NRR - Braidwood Units 1 and 2 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 Braidwood Station, Units 1 and 2 (23 pages)

FLOODING WALKDOWN REPORT IN RESPONSE TO THE 50.54(f) INFORMATION REQUEST REGARDING NEAR-TERM TASK FORCE RECOMMENDATION 2.3: FLOODING Preparer:

Reviewer:

Approver:

Lead Responsible Engineer Branch Manager:

Senior Manager:

Corporate Acceptance:

for the BRAIDWOOD NUCLEAR POWER STATION 35100 South Route 53 Braceville, IL 60407 Facility Operating License No. NPF-72/NPF-77 NRC Docket No. 50-456/50-457

,,~ Exeton~J Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Prepared by:

Sargent & Lundy LLC 55 East Monroe Chicago, IL 60603 100% Report, Rev. 1 November 9, 2012 Printed NameOitle Dean W. Robinson Program Manager, Sargent & Lundy Jeffrey Kerruish Manager, Sargent & Lundy Dinesh C. Patel Project Manager, Sargent & Lundy Signature 11/13/12 Joseph V. Bellini/Corporate SME

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Contents

1.

EXECUTIVE

SUMMARY

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

2.

PURPOSE.................................................................................................................................................... 3

a.

Background........................................................................................................................................... 3

b.

SiteDescription..................................................................................................................................... 4

c.

RequestedActions................................................................................................................................ 5

d.

RequestedInformation......................................................................................................................... 5

3.

METHODOLOGY......................................................................................................................................... 6

a.

OverviewofNEI1207(WalkdownGuidance)..................................................................................... 6

b.

ApplicationofNEI1207....................................................................................................................... 7

c.

ReasonableSimulations........................................................................................................................ 8

d.

WalkdownInspectionGuidance........................................................................................................... 9

4.

RESULTS................................................................................................................................................... 10

a.

RequestedInformationItem2(a)-DesignBasisFloodHazards........................................................ 10

b.

RequestedInformationItem2(b)-CLBProtectionandMitigationFeatures.................................... 12

c.

RequestedInformationItem2(c)-FloodWarningSystems.............................................................. 13

d.

RequestedInformationItem2(d)-FloodProtectionSystem/BarrierEffectiveness......................... 13

e.

RequestedInformationItem2(e)-ImplementationofWalkdownProcess...................................... 14

f.

RequestedInformationItem2(f)-FindingsandCorrectiveActionsTaken/Planned........................ 15

g.

RequestedInformationItem2(g)-Cliff-EdgeEffectsandAvailablePhysicalMargin..................... 16

h.

RequestedInformationItem2(h)-Planned/NewlyInstalledFloodProtectionEnhancements....... 17

5.

CONCLUSIONS.......................................................................................................................................... 17

6.

REFERENCES............................................................................................................................................. 21

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1. EXECUTIVE

SUMMARY

In response to the Nuclear Regulatory Commission (NRC) Request for Information regarding NearTerm TaskForce(NTTF)Recommendation2.3,afloodingwalkdownwasconductedatBraidwoodPowerStation (BWD) to verify that plant features credited in the current licensing bases (CLB) for protection and mitigation from external flood events are available, functional, and properly maintained. The flooding walkdownwasconductedbetweenAugust13andAugust17,2012andonOctober16,2012.

Thescopeofthefloodingwalkdownwasdevelopedfollowingadetailedreviewofallrelevantlicensing documents. Since BWD is situated above the probable maximum flood (PMF) level, the station relies entirely on passive features incorporated in the design to keep water out of the plant, specifically site runoff from a local intense precipitation (LIP) event and groundwater. The flooding walkdown scope consistedoftwomainparts.

Anoutdoorwalkdownwasconductedtoverifythatplantmodificationsimplementedsinceoriginal construction, such as security barrier installation and changes to topography, do not adversely affectplantfloodingprotection.

The belowgrade structures (i.e., basement walls and basement slabs and penetrations through thesewallsandfloors)inthemainpowerblockthatarecreditedintheCLBtokeepgroundwater andrunofffromLIPoutofthesafetyrelatedbuildingswereinspected.

Themethodologyandacceptancecriteriafortheevaluationoffloodprotectionfeatureswasdeveloped basedonNEIreport1207[Rev0A](Reference2),GuidelinesforPerformingVerificationWalkdownsof PlantProtectionFeatures.Thewalkdownscopedevelopedincluded31floodprotectionfeatures.Visual inspectionsofwalls,floorsandpenetrationsthroughthewallsandfloorswereconductedtoverifythere arenoobservablestructuraldeficienciesthatmayimpactthestructuresabilitytoperformitsintended flood protection function. Inspections of walls, floors and penetrations confirmed that credited flood barriersareinplaceandappeartobecapableofperformingtheirintendedfunction.Whetherconduits frommanholesorcablevaultsthatcouldprovideapathforgroundwaterorrainwatertoentersafety relatedbuildingswereconsideredrelevanttothewalkdownscope.Conduitsfrommanholes/cablevaults generallyarenotroutedtosafetyrelatedbuildingsatBWD.Inafewcases,thereareenteringconduitsthat turn up and terminate above grade level such that no path for water is provided. Evidence of groundwater/rainwaterleakagethroughconduitsintosafetyrelatedbuildingsatBWDwasnotidentified.

ConduitsatBWDdonotprovideapathforgroundwaterorrainwatertoentersafetyrelatedbuildings.

TheUnit1auxiliaryfeedwatertunnelwasconsideredarestrictedaccessareaandinspectionwasdeferred untilanoutage.ThenextUnit1refuelingoutageiscurrentlyscheduledforSeptember2013.

Performanceofthewalkdownsprovidedconfirmationthatfloodprotectionfeaturesareinplace,arein goodconditionandwillperformascreditedinthecurrentlicensingbasis.Observationsnotimmediately judgedasacceptablewereaddressedanddispositionedundertheCAPprogram.

Atotalof35IncidentReports(IRs)wereenteredintheCAPasaresultofthiseffort.TheseIRsaredescribed in Table 2 in the Conclusion section of this report. The outcome of the CAP dispositions identified no reportabledeficiencyfindings.TherearenoobservationsawaitingfinaldispositioninCAP.

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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.(Seenotebelowregardingcliffedgeeffects.)

Structures,systems,andcomponents(SSCs)importanttosafetyaredesignedeitherinaccordancewith,or meettheintentof,AppendixAto10CFRPart50,GeneralDesignCriteria(GDC)2.GDC2statesthatSSCs important to safety at nuclear power plants must be designed to withstand the effects of natural phenomena, including floods, without loss of capability to perform their intended safety functions. For flooding walkdowns, identifying/addressing plantspecific degraded, nonconforming, or unanalyzed conditions (through the corrective action program) and verifying the adequacy of monitoring and maintenanceproceduresisassociatedwithfloodprotectionandmitigationfeaturescreditedinthecurrent design/licensing basis. New flood hazard information will be considered in response to Enclosure 2 of Reference3.

OnbehalfofExelonGenerationCompany,LLC(Exelon),thisreportprovidestheinformationrequestedin theMarch12,50.54(f)letter;specifically,theinformationlistedundertheRequestedInformationsection ofEnclosure4,paragraph2(athroughh).TheRequestedInformationsectionofEnclosure4,paragraph 1 (a through j), regarding flooding walkdown procedures, was addressed via Exelons June 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

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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. SiteDescription PerUpdatedFinalSafetyAnalysisReport(UFSAR)Section2.4,BraidwoodStationislocatedabout4miles southwestoftheKankakeeRivernearthetownofCusterParkinastripminedregionpresently characterizedbymanywaterfilledtrenchesandponds.Theplantissitedonalowridgesouthwestofthe KankakeeRiverandeastoftheMazonRiver.TheKankakeeRiverjoinstheDesPlainesRiverabout10miles directlynorthofthesitetoformtheIllinoisRiveratrivermile273.TheMazonRiverflowsintotheIllinois Riveratmile264.OtherstreamsintheareaareCrane,Granary,andHorseCreeks.Exceptforponded waterinthestripminedareasaroundBraidwoodandGodley,therearenopondsintheregion.(Reference 13)

PerUFSARSection2.4,theplantgradeelevationisat600.0feet(allelevationsrefertoUSGS1929datum) whilethegradefloorsofthesafetyrelatedbuildingareatelevation601.0feet.(Reference13)Floodson theKankakeeRiverwouldaffecttheriverscreenhouse,anonsafetyrelatedstructurenotprotectedfrom PMF.Shouldmakeupwaterfromtheriverscreenhousetothecoolingpondbeeliminated,thecooling pondcanoperateunderaclosedcyclesystem.Theprobablemaximumflood(PMF)levelsalongthe KankakeeRiver,MazonRiver,andGranaryCreekdonotaffectthesite,sincethemaximumwatersurface elevationsare561.3,582,and576feet,respectively;aminimumof18feetbelowtheplantgrade.

Coolingwaterfortheplantissuppliedbyacoolingpondwhichcoversoneofthestripminedareas.The pondhasanaveragedepthofapproximately8.21feetwithasurfaceareaof2475acresandastorage volumeof22,300acrefeetatitsnormalpoolelevationof595feet.Thecoolingpondiscontainedbydikes.

(Reference13)

PerUFSARSection2.4,thecontrollingeventforfloodingatBraidwoodstationisthePMFforthecooling pond.Thiseventhasbeenanalyzedbyapplyingaprobablemaximumprecipitation(PMP)totheponds watershedfollowinganantecedentstandardprojectflood(SPF)equivalenttoonehalfofthePMP.The maximumwatersurfaceelevationinthecoolingpondresultingfromthePMFwithantecedentSPFis 598.17feet.Thecoolingponddikeelevationis600.0feet,exceptforthatareasouthoftheplantwhere thedikeelevationis602.5feet.Thedikeismaintainedatahigherelevationinthisareatopreventsplash overresultingfrompossiblerunupduetowindwaveactiontoelevation602.34feet.(Reference13)

Thesitedrainagesystemisdesignedtofollowthenaturaldrainagepatternandtodrainthestormwater awayfromtheplantarea.Theareassurroundingtheplantbuildingsaregradedtodirectthesurfacerunoff towardsnorth,west,andeastoftheplantarea.Alocalintenseprecipitation(LIP)eventispostulatedto occurforashortperiodoftimeuntiltherunoffdrainsfromtheplantsiteovertheroadsandrailroadsand thedrainagesystem.(Reference13)

Thenearesthighwaystothesite,IllinoisStateRoutes53and129,areadjacenttothenorthwestboundary ofthesite.Interstate55islessthan2mileswestnorthwestofthesite(centerlineofthereactors),and

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StateRoute113isapproximately2milesnorthofthesite.AccesstotheplantisviaStateRoute53.Onsite roadsintheimmediateplantareavaryinelevationfrom598.0feetto601.0feet.Noneoftheseroads would be affected by the PMF from the rivers or cooling pond. The Illinois Central Gulf Railroad runs paralleltoandbetweenStateRoutes53and129providesspurtrackaccesstothesite.(Reference13)

c. RequestedActions 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.

OtherNRCsrequestedactionsinclude:

(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.

Per Enclosure 4 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. RequestedInformation PerEnclosure4ofReference3,

1. TheNRCrequeststhateachlicenseeconfirmthatitwillusetheindustrydeveloped,NRCendorsed, floodingwalkdownproceduresorprovideadescriptionofplantspecificwalkdownprocedures.As indicatedpreviously,ExelonsletterdatedJune11,2012(Reference1),confirmedthattheflooding walkdownprocedure(Reference2),endorsedbytheNRConMay31,2012,willbeusedasthe basisforthefloodingwalkdowns.

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.

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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.

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. OverviewofNEI1207(WalkdownGuidance)

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

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o VarietyOfSiteConditions o FloodDuration 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. ApplicationofNEI1207 AtBraidwood,theapproachtothefloodingwalkdownsincludedthreephases:

Phase1-Preparation,Training,DataGathering,andScoping Exelon developed a fleetwide program and training course for walkdown team members to providecompleteandconsistentimplementationofNEI1207guidelines.Inaddition,allwalkdown teammemberscompletedtheapplicableNANTeLtrainingandtesting.Datagatheringbeganwith identificationofstationspecificlicensingcommitmentsandstationdesignbasisrelativetoexternal floodingevents.ThisincludedreviewoftheBraidwoodUFSARSections2.4and3.4(Reference13),

identificationofdrawingsshowingfloodprotectionfeaturesandreviewofstationproceduresand calculations relative to external flooding events. A walkdown scope was developed to capture stationfeaturescreditedasperformingafloodprotectionfunctioninthecurrentlicensingbasis.A walkdownlistwaspreparedidentifyingthespecificfeaturestobeinspected.Foreachfeatureon

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thewalkdownlist,awalkdownpackagewaspreparedforusebythewalkdownteaminperforming anddocumentingthewalkdown.

ThescopedevelopedforthewalkdownsatBWDincludedthefollowing:

Thefloorsandexteriorwatertightwalls(uptomaximumgroundwaterwaterlevel)ofthe Auxiliary Building. The Containment Building was not included in the inspection scope because the exterior walls and the floor are credited with leak tightness based on the periodicILRTtesting.

Whetherconduitsfrommanholesorcablevaultscouldprovideapathforgroundwateror rain water to enter safety related buildings was considered relevant to the walkdown scope. Conduits from manholes/cable vaults generally are not routed to safety related buildingsatBWD.Inafewcasesthereareenteringconduitsthatturnupandterminate above grade level such that no path for water is provided. Evidence of groundwater/rainwaterleakagethroughconduitsintosafetyrelatedbuildingsatBWDhas notbeenidentifiedinthepastandwasnotidentifiedduringthewalkdowns.Conduitsat BWDdonotprovideapathforgroundwaterorrainwatertoentersafetyrelatedbuildings.

Anoutdoorwalkdownwasconductedtoverifythatplantmodificationsimplementedsince originalconstruction,suchassecuritybarrierinstallationandchangestotopography,do notadverselyaffectplantfloodingprotection.

Phase2-InspectionsandReasonableSimulations

Visual inspection of each feature was performed on the walkdowns and the results were documentedontheWalkdownRecordForms.Theconditionofeachfeatureasobservedonthe walkdowns was compared to the acceptance criteria defined in the Supplemental Walkdown/Inspection Guidance (Reference 19). No reasonable simulations were conducted at BWDsinceallfeaturesareincorporatedpassive.

Phase3-FinalReporting

The Walkdown Record Forms were completed and assembled into a package that included a summaryandacoverpagetodocumentamanagementreviewoftheentirepackage.Completion of the Walkdown Record Forms was performed in accordance with the guidance provided in Section7ofNEI1207.AFloodingWalkdownReport(thisreport)waspreparedtoaddressthe items outlined in the Requested Information section of the Recommendation 2.3: Flooding enclosurefromthe10CFR50.54(f)letter.

c. ReasonableSimulations PerNEI1207(Reference2),reasonablesimulationincludesthefollowing:

Verifythatanycreditedtimedependentactivitiescanbecompletedinthetimerequired.Time dependentactivitiesincludedetection(somesignalthattheeventwilloccur,hasoccurred,oris

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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).

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 have been previously performed and documented or it is periodically demonstrated and documentedthattheactivitiescanbecompletedinthecreditedtime.

Thepurposeofreasonablesimulationsistoverifyrequiredfloodprotectionproceduresoractivitiescanbe executedasspecified/written.Braidwoodfloodprotectionfeaturesdonotincludeanytemporaryoractive featuresthatrequireimplementationofaprocedureforperformanceofmanual/operatoractionsinorder forthefeaturetoperformitsintendedfloodprotectionfunction.Therefore,noprocedurewalkthrough,or ReasonableSimulation,wasconductedatBraidwoodStation.

d. WalkdownInspectionGuidance AWalkdownInspectionGuidancewasdevelopedbyExelontosupplementNEI1207(Reference2),based largelyonAppendixAofNEI1207(Examples).Theguidancewasintendedtosupplement,notsupersede, NEI1207andprovideinspectionguidanceforspecificfeatures,listedbelow.

IncorporatedorExteriorPassiveFeatures:

o SiteElevationsandTopography o EarthenFeatures(i.e.,FloodProtectionBerm,Dike,Levee) o ConcreteandSteelStructures

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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. RequestedInformationItem2(a)-DesignBasisFloodHazards Describe the design basis flood hazard level(s) for all floodcausing mechanisms, including groundwater ingress.

TheBraidwoodStationdesignbasisforexternalfloodingisdescribedinBWDUFSARSections2.4and 3.4(Reference13).Braidwoodisdesignedtobeprotectedfromtheeffectsofriverflooding,cooling pond flooding and a LIP event. In addition, the safety related structures at Braidwood Station are designedtobeprotectedagainstgroundwateringress.AsummaryoftheBraidwoodfloodinghazards areprovidedinthetablebelow:

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No.

HazardType MaximumElevation (feet)

Source 1

KankakeeRiverFlooding 561.3 UFSARSection2.4.3 2

MazonRiverFlooding 582 UFSARSection2.4.10 3

GranaryCreekFlooding 576 UFSARSection2.4.10 4

CoolingPondFlooding 602.34 UFSARSection2.4.10 5

LocalIntensePrecipitation 601.91 CalculationWRBRPF10,Rev14 6

GroundwaterIngress 600 UFSARSection2.4.13.3andDTST03 BY/BR,Rev.23,Section12.2.3.

AllsafetyrelatedequipmentisprotectedfromfloodbyvirtueofitslocationabovethehighestPMF elevationandbybeinghousedwithinfloodprotectedstructures.TheRiverScreenHouseistheonly structurethatcouldbeaffectedbyfloodingfromtheKankakeeRiver.However,perUFSARSection 2.4.2.2,theRiverScreenHouseisanonsafetyrelatedstructurenotprotectedfromPMF.PerUFSAR Section2.4.11.6,shouldmakeupwaterfromtheriverscreenhousetothecoolingpondbeeliminated, thecoolingpondcanoperateunderaclosedcyclesystem.(Reference13).

PerUFSARSection2.4.2.3(Reference13),theplantgradeelevationisat600.0feetwhilethegrade floorsofthesafetyrelatedbuildingareatelevation601.0feet.ThePMFalongtheKankakee River, MazonRiver,andGranaryCreekdonotaffectthesite,sincethemaximumwatersurfaceelevationsare 561.3,582,and576feet,respectively;aminimumof18feetbelowtheplantgrade.

ThecontrollingeventforfloodingatBraidwoodstationisthePMFforthecoolingpond.Thiseventhas beenanalyzedbyapplyingthePMPtothepondwatershedfollowinganantecedentSPF,equivalentto onehalfofthePMP.ThemaximumwatersurfaceelevationinthecoolingpondresultingfromthePMF with antecedent SPF is 598.17 feet (UFSAR Section 2.4.4, Reference 13). The cooling pond dike elevationis600.0feet,exceptforthatareasouthoftheplantwherethedikeelevationis602.5feet (UFSAR Section 2.4.8.2, Reference 13). The dike is maintained at a higher elevation in this area to preventsplashoverresultingfrompossiblerunupduetowindwaveactiontoelevation602.34feet (UFSARSection2.4.8.2,Reference13).

Braidwoodsmainpowerblockbuildingissituatedatgradeelevation600feet,abovethemaximum PMFlevel.Theportionofthebuildingsubstructureslocatedbelowthemaximumgroundwaterlevel aredesignedtopreventgroundwateringress.ThedesigngroundwaterelevationatBraidwoodis600 feet(StructuralProjectDesignCriteriaSection12.2.3,Reference13,14).

The latest design basis calculation for effect of local probable maximum precipitation at plant site (CalculationWRBRPF10,Rev.14)liststhemaximumfloodingelevationinPMPZoneBas601.91feet.

TheresultingdesignbasisLIPpeakwaterelevationattheexteriorpowerblockwallsis601.91feet.in theimmediatestationareawherethesafetyrelatedfacilitiesarelocated(easthalfofthemainpower block structure). It is noted that the Braidwood walkdowns were conducted on the basis that the maximum LIP elevation for Zone B is602 feet. A conservative assumption made in the design basis evaluationwasthatstormwaterdrainagesystem,includingsiteditches,doesnotfunctionduringthe LIP(UFSARSection2.4.2.3,Reference13).Theareassurroundingtheplantaregradedtodirectsurface runoff away from the plant. Also, the equation for peak LIP flow conservatively assumed a runoff

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coefficientof1.0(zerolossesor100%runoff).Thestationssafetyrelatedbuildingfloorisatelevation 601feet.

Braidwood UFSAR Sections 2.4.4 through 2.4.7 addresses additional flooding mechanisms that are eithernotcriticalornotboundingforBraidwood.Probablemaximumsurgeandseichefloodingisnot boundingforBraidwoodbecausethereisnolargebodyofwaternearthesitewheresignificantstorm surgesandseicheformationscanoccur.Thestationwillnotbesubjectedtotheeffectsoftsunami floodingbecausethephysicallocationofBraidwoodStationisnotadjacenttoacoastalarea.Similarly, adamfailureortheeffectsoficejamfloodingaredeterminedtonotaffectthesafetyrelatedfacilities.

b. RequestedInformationItem2(b)-CLBProtectionandMitigationFeatures Describeprotectionandmitigationfeaturesthatareconsideredinthelicensingbasisevaluationtoprotect againstexternalingressofwaterintoSSCsimportanttosafety.

Withinthemainpowerblockstructures,thereissafetyrelatedequipmentlocatedbelowgradeinthe Auxiliary,ContainmentandLakeScreenHousebuildings.Nobelowgradesafetyrelatedequipmentis locatedintheFuelHandling,TurbineorRadwastebuildings.Potentialsourcesofexternalfloodingof themainpowerblockbuildingsareLIPandgroundwateringress.Thedesigngroundwaterelevationat Braidwoodis600feet,whichisthesitegradeelevation(UFSARSection2.4.2.3,Reference13).Insafety relatedbuildings,waterstopsareprovidedinallconstructionjointsandwatersealsareprovidedforall penetrations(UFSARSection2.4.14.2,Reference13).ThedesigngroundwaterelevationatBraidwoodis 600feet(StructuralProjectDesignCriteriaSection12.2.3,Reference14).ThemaximumdesignbasisLIP watersurfaceelevationis601.91feetintheimmediatestationareawheresafetyrelatedfacilitiesare located(Auxiliary,ContainmentandFuelHandlingbuilding).PerCalculationWRBRPF10(Reference 22),localsurfacedrainagesystemsareconservativelyassumednottofunctionduringtheLIPevent.

Theareassurroundingtheplantaregradedtodirectsurfacerunoffawayfromtheplant.

AllfloodprotectionfeaturesatBraidwoodthataredesignedtoprotectsafetyrelatedequipmentare passiveincorporatedfeatures,andassuchdoesnotinvolveinvokinganyprocedures.Suchfeatures includethewalls,floorsandceilingsofbuildingswhichhousethesafetyrelatedequipment.Reinforced concretecurbsorsteelbarriersareprovidedattheentrancetotheMainSteamIsolationValve(MSIV)

Rooms(Reference16).Inaddition,twopassivefloodprotectionstructuresareprovided,includinga concrete slab in Radwaste Tunnel (Reference 23) and a concrete slab in the Fuel Handling Building inside the spent fuel pit pump rooms (Reference 17). No temporary flood protection features or proceduresareincludedintheBraidwooddesignforprotectionofsafetyrelatedequipment Thelicensingbasisdoesnotexplicitlyaddressflooddurationoradverseweatherconditionsconcurrent withflooding,presumablybecausetheprotectionfeaturesareallincorporatedpassive.Inaddition, Braidwoodfloodprotectionfeaturesaredesignedtofunctionduringanyplantmodeofoperation.

TheBraidwoodLakeScreenHouseforebayhousessafetyrelatedEssentialServiceWater(SX)System piping including manual valves 0SX115A/B/C/D/E/F (Reference 18) but contains no safety related electrical components. The piping provides suction to the safety related SX System pumps 1/2SX01PA/PB, which are located in the Auxiliary Building (Reference 18). The manual valves 0SX115A/B/C/D/E/F are normally open and are utilized for periodic inspection and maintenance purposesonly.Thesevalvesarenotrequiredtobemanipulatedtorespondtoanyplantdesignbasis

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accident(includingallUFSARchapter15accidentsandinternalAuxiliaryBuildingflooding).Basedon thisinformation,thefloodprotectionfeaturesoftheLakeScreenHousewerenotinspected.

Duct run drawings 20E03680 and 20E03681 (Reference 20) show there is no direct path from undergroundelectricalmanholesintothesafetyrelatedAuxiliaryandContainmentBuildings.

c. RequestedInformationItem2(c)-FloodWarningSystems Describeanywarningsystemstodetectthepresenceofwaterinroomsimportanttosafety.

PerUFSARSection9.2.1.2.4(Reference13),leakdetectionisprovidedbymeansofsystemflowand pressuredropinstrumentationandleakdetectionsumpsintheAuxiliaryBuildingbasementwherethe essentialservicewaterpumpsareinstalled.The1Aand2Aessentialservicewaterpumpsarelocatedin onecompartmentandthe1Band2Bpumpsarelocatedinaseparateadjacentcompartment.Each compartmentcontainsanessentialservicewatersump(Reference21).Althoughdesignedtodetect internalflooding,theleakdetectionsumpswillalsodetectsignificantgroundwateringressintothese rooms.

d. RequestedInformationItem2(d)-FloodProtectionSystem/BarrierEffectiveness 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,toprovide morespecificcriteriaforjudgingacceptance.Allobservationsthatcannotbeimmediatelyjudgedas acceptablewereenteredintothesitesCorrectiveActionProgram(CAP)whereanevaluationofthe observationcanbemade.

Walkdownswereconductedtoverifytheexteriorwalls,floors,seals,andceiling,creditedforkeeping wateroutofsafetyrelatedareas,arecapableofperformingtheirintendedfunctionbasedonvisual observations.FloodprotectionfeaturesinspectedatBraidwoodalsoincludedtheexternalhatchesthat provide access to the refueling water storage tank piping tunnels and the interface between the Radwaste Building and the Auxiliary Building Radwaste tunnel. The purpose of the walkdowns is to verifyconformancewiththeBraidwoodcurrentlicensingbasis.Theadequacyofthecurrentlicensing basis will be addressed in response to NTTF Recommendation 2.1. An outdoor walkdown was conductedtoverifythatplantmodificationsimplementedsinceoriginalconstruction,suchassecurity barrierinstallationandchangestotopography,donotadverselyaffectplantfloodingprotection.

Acceptancecriteriaforvisualinspectionsperformedduringthewalkdownsweredevelopedtoidentify conditionsadversetoqualityandincludedthefollowingconsiderations:

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Floodprotectionconfigurationisinaccordancewithdesigndrawingsandthestationcurrent licensingbasis.

Visualinspectiondidnotidentifyanymaterialdegradation.Adetailedlistingofacceptance criteriaforvisualinspectionswasutilizedbythewalkdownteamduringperformanceofthe walkdowns.

Notopographychanges,includingsecuritybarrierinstallations,werefoundtoadverselyaffect thesitedrainage.

Whetherconduitsfrommanholesorcablevaultscouldprovideapathforgroundwaterorrainwaterto entersafetyrelatedbuildingswereconsideredrelevanttothewalkdownscope.Conduitsfrom manholes/cablevaultsgenerallyarenotroutedtosafetyrelatedbuildingsatBWD.Inonelocation, thereareconduitsenteringtheAuxiliaryBuildingfromaductrunthatturnupandriseembeddedinthe towalltowellabovegradelevelsuchthatnopathforwaterisprovided.Evidenceof groundwater/rainwaterleakagethroughconduitsintosafetyrelatedbuildingsatBWDwasnot identified.ConduitsatBWDdonotprovideapathforgroundwaterorrainwatertoentersafetyrelated buildings.(Reference20)

ThefloodprotectionfeaturesincorporatedintotheBraidwooddesignprovideeffectivebarriersfor keepingexternalfloodingfromreachingsafetyrelatedsystemsandequipment.However,the walkdownsanddocumentreviewsresultedinobservationsthatcouldnotimmediatelybejudgedas acceptable.Thesewereenteredintothecorrectiveactionprogram(CAP)fordisposition.AllIRs enteredinCAPhavebeendispositionedwithnoresultingreportabledeficienciesidentified.

Inadditiontothesewalkdowns,thestationstructuralmonitoringprogram(Reference15)andvarious preventativemaintenanceactivitiesprovideforongoingverificationoffloodbarriereffectiveness.

e. RequestedInformationItem2(e)-ImplementationofWalkdownProcess 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.

Station walkdowns were implemented in accordance with the guidelines provided in NEI 1207 (Reference2).TheBraidwoodwalkdownteamincludedfourSargent&Lundyemployeesaswellasthe BraidwoodLeadResponsibleEngineerforfloodingissues.Allteammemberswerefamiliarwiththe station licensing basis relative to external flooding, are badged at Braidwood and completed both NANTeLbasedtrainingandExelonspecifictrainingonimplementationoftheNEI1207guidelines.The Sargent&LundyteamconsistedofthreemechanicalengineersfamiliarwithBraidwoodStationand one civil engineer. At least two Sargent & Lundy team members performed all visual inspections.

Walkdown results were documented using the NEI 1207 recommended form. Walkdown packages, oneforeachfeature,werepreparedinadvanceandincludedtheNEI1207walkdownformwithParts AandBalreadycompletedaswellasreferencedrawingsanddocumentation.Theremainingpartsof thewalkdownformswerefinalizedafterthefeaturewalkdownwascompleted,andtheidentification ofobservationsenteredintoCAP.WalkdownswereconductedfollowingtheguidanceofNEI1207and noexceptionsweretakentotheguidance.

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f. RequestedInformationItem2(f)-FindingsandCorrectiveActionsTaken/Planned Resultsofthewalkdownincludingkeyfindingsandidentifieddegraded,nonconforming,orunanalyzed conditions.Includeadetaileddescriptionoftheactionstakenorplannedtoaddresstheseconditionsusing theguidanceinRegulatoryIssuesSummary200520,Rev1,RevisiontoNRCInspectionManualPart9900 TechnicalGuidance,OperabilityConditionsAdversetoQualityorSafety,includingenteringthecondition inthecorrectiveactionprogram.

Thewalkdownscopewasdevelopedtoconfirmthatfloodprotectionfeaturescreditedinthecurrent licensingbasisareacceptableandcapableofperformingtheircreditedfloodprotectionfunctions.For Braidwood Power Station the scope primarily consisted of visual inspections of floors and exterior watertight walls in the main power block. The scope included visual inspection of all applicable penetrations and associated seals. In addition, an outdoor walkdown was conducted to confirm credited surface drainage provisions have not been impacted by changes to topography, such as installationofnewsecuritybarriers.Inspectionsofcreditedwalkdownfeatureswereperformedbythe walkdown team following the guidance provided in NEI 1207 and were documented in walkdown packagesusingtheNEI1207walkdownforms.WalkdownrecordformsarenotsubmittedtotheNRC, butasdiscussedinSection7ofReference2areretainedonsiteforNRCinspection.Observationsof degraded, nonconforming or unanalyzed conditions were documented and entered into the station correctiveactionprogram(CAP).

Theinspectionsofwalls,floorsandpenetrations/sealsverifiedthatcreditedfloodbarriersareinplace and appear capable of performing their intended flood protection function. A total of 35 IRs were generatedintheprocessofperformingthewalkdowns.Thesearesummarizedbelowandarelisted, alongwiththeresolutionstatus,inatableintheConclusionssectionofthisreport.AlloftheIRswere resolvedinCAPandresultedinzeroreportabledeficiencies.

ObservationsNotImmediatelyJudgedasAcceptable IRs 1400281, 1400274, 1400269, 1400261, 1400245, 1400732, 1400730, 1400728, 1400727, 1402930,1403499,1404165,1404065,1404765and1428041documenttheevidenceofpast groundwaterintrusion.

IRs1400267,1402279and1402752documentcurrentminorgroundwaterleakage.

IR1401170documentsamoundofsoilonthenorthsideoftheturbinebuildingthatpartially blocksraindrainagepath.

IRs 1402065 and 1402113 document small pipes inserted into expansion joint that requires repair.Noevidenceofwaterintrusion.

IR1402151documentsapipedrainprotrudingfromaRWSTtunnelmanholecurb.Thepipewas determinednottobeapotentialfloodpath.

IR 1402163 and 1402706 documented housekeeping issues identified during the flooding walkdownbutunrelatedtofloodprotection.

IR1402170documentswatercondensationonRWSThatch.

IR 1402633 documents degraded expansion joint. No evidence of leakage. The sealant is scheduledtoberepairedtoanacceptablecondition.

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IR 1402965 documents a concrete spall in the CS pump room. No active leakage and no structuralimpact.

IR1403453documentslowavailablephysicalmarginof0.1feetfromfloodelevationtotopof concretebarrierinradwaste/servicebuildingtunnel.IR1427443identifiesthatthecurrentPMP calculationcanberevisedsoastorecoveradditionalmargin.

IR1404810documentsthatitisuncleariftheservicebuildingadditionprojectwasaccounted forinthePMPcalc.

IR1390831documentswaternotedonfloorunderRWSThatch.Hatchrepairisscheduled.

IR 1427471 documents a puddle found in the aux. feedwater tunnel presumably from groundwaterinleakage.Leakrateisslowandnotimpactingplantequipment.Theissuewillbe investigatedtodeveloprepairrecommendationsifnecessary.

IR 1427832 documented a deficiency tag identifying groundwater inleakage. No work order documentingthatthisdeficiencyhadbeenaddressedwasfound.Theissuewillbeinvestigated todeveloprepairrecommendationsifnecessary.

ObservationsDesignatedthroughCAPasDeficient None.

ObservationsAwaitingFinalDispositioninCAP None.

RestrictedAccessAreas IR1410811documentsdeferralofinspectionoftheUnit1aux.feedwatertunneluntilthenextUnit1 refueling outage, currently scheduled for September 2013. IR 1410845 documented deferral of the corresponding Unit 2 walkdown, however, this walkdown was subsequently performed during the October2012Unit2refuelingoutage.

InaccessibleAreas None.

g. RequestedInformationItem2(g)-Cliff-EdgeEffectsandAvailablePhysicalMargin Documentanycliffedgeeffectsidentifiedandtheassociatedbasis.Indicatethosethatwereenteredinto the corrective action program. Also include a detailed description of the actions taken or planned to addresstheseeffects.

Cliffedge effects were defined in the NTTF Report (Reference 5) as the safety consequences of a floodingeventmayincreasesharplywithasmallincreaseinthefloodinglevel.AsindicatedinSections 3.12 of NEI 1207 (Reference 2), the NRC is no longer expecting the Recommendation 2.3: Flooding Walkdownstoincludeanevaluationofcliffedgeeffects.TheNRCisnowdifferentiatingbetweencliff edgeeffects,whichareaddressedinEnclosure2ofReference3,andAvailablePhysicalMargin(APM).

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AsindicatedinSections3.13ofNEI1207(Reference2),APMdescribesthefloodmarginavailablefor applicablefloodprotectionfeaturesatasite(notallfloodprotectionfeatureshaveAPMs).TheAPMfor eachapplicablefloodprotectionfeatureisthedifferencebetweenlicensingbasisfloodheightandthe floodheightatwhichwatercouldaffectanSSCimportanttosafety.

APMinformationwascollectedduringthewalkdownsinaccordancewithguidanceprovidedinNEI12 07 and the final resolution to FAQ006. APM was collected to primarily support the response to ofReference3and,assuch,isnotincludedinthisreport.APMdeterminationsdidnot involvecalculatingcliffedgeeffects(i.e.thesafetyconsequences).DuringtheIntegratedAssessment (seeEnclosure2ofReference3),thecliffedgeeffectsandtheassociatedsafetyriskswillbeevaluated usingtheAPMsandotherinformation,suchasthespecificSSCsthataresubjectedtofloodingandthe potentialavailabilityofothersystemstomitigatetherisk.

Since the walkdowns potentially impacting cliff edge effects were completed prior to the final resolutionofFAQ006(September13,2012),APMinformationwascollectedanddocumentedonthe Walkdown Record Form using the old approach; that is, a simple measurement of the difference between the licensing basis flood height and the flood height at which water could affect an SSC importanttosafety.

h. RequestedInformationItem2(h)-Planned/NewlyInstalledFloodProtection 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.

Noplannedornewlyinstalledfloodprotectionenhancementsweredeterminedtobenecessaryasa resultofthefloodwalkdownsatBraidwood.

5. CONCLUSIONS Inspections of walls, floors and penetrations confirmed that credited flood barriers appear to be capableofperformingtheirintendedfunction.AllIRsenteredintotheCAPhavebeenaddressedand arenotreportabledeficiencies.InspectionoftheUnit1auxiliaryfeedwatertunnelwasdeferreduntilan outagewhenaccesswillbeprovided.

Table1providesasummaryofthenumberandtypeoffeaturesincludedinthewalkdownscope.

Table2providesthelistoftheIRsgeneratedandenteredintothestationcorrectiveactionprogram (CAP)asaresultofthewalkdown.ThestatusofeachIRatthetimeofthisreportisindicated.Noneof theseIRsresultedinanoperabilityconcernandnonearereportabledeficiencies.

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Table1:FeaturesIncludedintheWalkdownScope Type

1. ofVisual Inspections

1. ofSimple Simulations

1. ofComplex Simulations

1. ofDrillsor Exercises Incorporated/ExteriorPassive 31 0

0 0

Incorporated/ExteriorActive 0

0 0

0 TemporaryPassive 0

0 0

0 TemporaryActive 0

0 0

0 Totals 31 0

0 0

Table2:IRsGeneratedinCAP IRNumber Description ProposedResolution Status/Resolution 1400281 Unit2,BSXpumproom,evidence ofpastgroundwaterintrusion.No activeleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

1400274 Unit1,ASXpumproom,evidence ofpastgroundwaterintrusion.No activeleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

1400269 Unit2,dieseloiltankroom2A, evidenceofpastgroundwater intrusion.Noactiveleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

1400267 Unit1,mainsteamtunnelandMSIV rooms1Band1C,minor groundwaterleakage.Currently monitoredbystation.

Closetoactionstakenandtrend.

Closetoactionstaken.

1400261 Unit1,mainsteamtunnelandMSIV rooms,evidenceofpastgroundwater intrusion.Noactiveleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

1400245 Unit2,dieseloiltankroom2B, evidenceofpastgroundwater intrusion.Noactiveleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

1400732 Unit2,364elevationinArea7, evidenceofpastgroundwater intrusion.Noactiveleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

1400730 Unit1,343and346elevationin Area5,evidenceofpastgroundwater intrusion.Noactiveleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

1400728 Unit2,343elevationinArea7, evidenceofpastgroundwater intrusion.Noactiveleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

1400727 Unit1,364elevationinArea5, evidenceofpastgroundwater intrusion.Noactiveleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

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Table2:IRsGeneratedinCAP IRNumber Description ProposedResolution Status/Resolution 1401170 Unit1,Amoundofsoilonnorthside ofturbinebuildingpartiallyblocks raindrainagepath.

RPtopresenttoPHCfor dispositionofthesoil.

ClosetopreexistingATI 138302105.

1402065 Unit2,A1/2diameterpipefound insertedintoexpansionjoint betweenoutsidecontainmentwall and2A/2DMSIVroom.Pipeneedsto beremovedandsealantrepaired.No evidenceofwaterintrusioninMSIV roominthisarea.

Sponsoredworkauthorization requiredtoinitiaterepair.

ClosetoWR409627.

CompletedWO156682101 10/23/12byLuse.

1402113 Unit2,A1/2diameterpipefound insertedintoexpansionjoint betweenoutsidecontainmentwall and2B/2CMSIVroom.Pipeneedsto beremovedandsealantrepaired.No evidenceofwaterintrusioninMSIV roominthisarea.

Sponsoredworkauthorization requiredtoacceleraterepair schedule.

ClosetoWR409617.Close toWO1566822being performedbyLuseduring A2R16.

1402151 Units1&2,Apipedrainwasfound protrudingfromcurbofRWSTtunnel manhole.Determinednottobea PMPfloodpath.

Needfordrainmayhavebeen eliminated.Engineeringto evaluate.

ER406310initiatedto evaluatethis.Drainlineis installedasrequiredbymod E20194245.

1402163 Unit2,seismichousekeepingissues identifiedinmechanicalmaintenance hotshopinauxiliarybuilding.

Issueshavebeenaddressed.

Closetoactionstaken.

1402170 Unit2,Watercondensationnotedon RWSThatch.

Sponsoredworkauthorization requiredtoinitiaterepair.

Worktobeperformed duringA2R16underWO 149772531.

1402279 Unit1,Veryminorgroundwater intrusionnotedinmainsteam tunnel.Areashouldbemonitoredto determineneedtoschedulerepairs.

MonitorthroughStructures MonitoringProgram.Closeto actionstakenandtrend.

Closetoactionstaken.

1402633 Unit2,Verticalinteriorexpansion jointbetweencontainmentandMSIV 2A/2Disdegraded.Noevidenceof waterintrusioninMSIVroominthis area.

InitiatedWR409752torepair.

ClosetoWR409752.This WO1572429iscancelledto aduplicateWO01068681 04/IR666968being performedduringA2R16.

1402706 Unit1,carpentershammerfoundin ahorizontalsupportmemberabove VLVleakoffdraintankpump.

Hammerhasbeenremoved.

Closetoactionstaken.

1402752 Unit2,Veryminorgroundwater intrusionnotedinmainsteamtunnel andMSIVrooms.Areaiscurrently monitoredtodetermineneedto schedulerepairs.

Monitorthroughstructural monitoringprogram.Closeto actionstakenandtrending.

Closetoactionstaken.

1402930 Unit2,evidenceofpastgroundwater intrusioninMSIVtunnelandMSIV rooms.Noactiveleakageatthese locations.

Closetoactionstakenandtrend.

Closetoactionstaken.

1402965 Unit1,Concretespallfoundinwallin containmentspraypumproom.No activeleakageandnostructural impact.

Monitorthroughstructural monitoringprogram.Closeto actionstakenandtrending.

Closetoactionstaken.

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Table2:IRsGeneratedinCAP IRNumber Description ProposedResolution Status/Resolution 1403453 Radwaste/servicebuildingtunnel floodbarrierslabhaslowavailable physicalmarginof0.1fromflood elevationtotopofslab.

Noactionsrequiredatthistime.

Closetoinformation providedintheIR.

1403499 Evidenceofpastgroundwater leakageinRadwastetunnel.No activeleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

1404165 Unit1,Evidenceofpastgroundwater leakageonaux.buildingLlinewall.

Noactiveleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

1404065 Unit2,Evidenceofpastgroundwater leakageonaux.buildingLlinewall.

Noactiveleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

1404765 Unit2,Evidenceofpastgroundwater leakageonaux.buildingfloorinArea 7.Noactiveleakage.

Closetoactionstakenandtrend.

Closetoactionstaken.

1404810 Uncleariftheservicebuilding additionprojectwasaccountedfor thePMPcalc.

Verifyservicebuildingaddition projectisaccountedforthePMP calc.Potentialimpactofissue determinedtonotbesignificant.

Basedonconversationswith engineering,theidentified issuewouldhaveno significantimpacton previousanalysisand conclusions;thereforeno previousanalysisis challenged.ATI140481002 todetermineifPMPevent hasbeenappropriately addressedwhenservice buildingwasinstalled.

1410811 Unit1,walkdownofaux.feedwater tunneldeferredtonextrefueling outageduetodifficultyofaccess.

WalkdownofUnit1aux.

feedwatertunneldeferredtonext refuelingoutage(A1R17).

Walkdowndeferredto outage.

1410845 Unit2,walkdownofaux.feedwater tunneldeferredtonextrefueling outageduetodifficultyofaccess.

WalkdownofUnit2aux.

feedwatertunneldeferredtonext refuelingoutage(A2R16).

Walkdowndeferredto outage.Thiswalkdownhas beencompleted10/16/12.

1390831 Unit1,waternotedonfloorunder RWSThatchinRWSTtunnel.

Scheduledhatchrepairshould eliminateanyhatchleakage.

ActionedtoWR00407567.

Identifiedduringseismic walkdown.WO1566429 working10/25/12-10/26/12A2R16.

1428041 Unit2,Evidenceofpastgroundwater leakageintheauxfeedtunnel.

Closetoactionstakenandtrend.

Closetoactionstaken.

1427471 Unit2,Puddlefoundatbottomof ladderintheauxfeedtunnel-apparentlygroundwaterinleakage.

Evaluateandprovide recommendationsforrepairif necessary SeeIRs1426707and 1430611.

1427832 Unit2,Deficiencytagfound identifyinggroundwaterinleakage.

Evaluateandprovide recommendationsforrepairif necessary EMD/CEtoperformwork duringA2R17createdfrom IR1430611.WR#415440 1427443 Unit1&2,PMPcalculationissue discovered.

Revisecalculationtorecover margin.

CalcWRBRPF10hasbeen revisedtoRev14torecover margin.

NTTFRecommendation2.3(Walkdowns):Flooding ExelonCorporation November9,2012 Revision1

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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].

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.

5. U.S.NuclearRegulatoryCommission.RecommendationsforEnhancingReactorSafetyinthe21st Century,TheNearTermTaskForceReviewofInsightsfromtheFukushimaDaiichiAccident.July12, 2011.

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

September26,2005.

7. InstituteofNuclearPowerOperations.FukushimaDaiichiNuclearStationFuelDamageCausedby EarthquakeandTsunami.INPOEventReport111.March15,2011.

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

9. U.S. Nuclear Regulatory Commission. Inspection of Structures, Passive Components, and Civil Engineering Features at Nuclear Power Plants. Inspection Manual. Inspection Procedure 62002.

Section03.01(h),Dams,EmbankmentsandCanals.

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

11. U.S.NuclearRegulatoryCommission.NRCInspectorFieldObservationBestPractices.NUREG/BR 0326,Rev.1.August2009.

12. U.S.NuclearRegulatoryCommission.FloodProtectionforNuclearPowerPlants.RegulatoryGuide 1.102.

13. BraidwoodUFSARRev.14.

14. Byron/BraidwoodStructuralProjectDesignCriteria,DCST03BBRev.23.

15. ExelonProcedureERAA450,Rev.1,StructuresMonitoring

16. DrawingsS899Rev.X,S900Rev.AA,S973Rev.W,S974Rev.AB

NTTFRecommendation2.3(Walkdowns):Flooding ExelonCorporation November9,2012 Revision1

Page22

17. DrawingS812Rev.AH

18. DrawingM42,Sheet1A,Rev.BI

19. SupplementalWalkdown/InspectionGuidance,Rev.0,8/7/12

20. Drawings20E03680Rev.AAand20E03667Rev.BE

21. DrawingM11Rev.P

22. CalculationWRBRPF10Rev.14,EffectofLocalProbableMaximumPrecipitation(PMP)atPlant Site

23. DrawingA47Rev.AS

U.S. Nuclear Regulatory Commission 180-Day Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding November 27, 2012 Page 4

SUMMARY

OF REGULATORY COMMITMENTS The following table identifies commitments made in this document. (Any other actions discussed in the submittal represent intended or planned actions. They are described to the NRC for the NRCs information and are not regulatory commitments.)

COMMITMENT TYPE COMMITMENT COMMITTED DATE OR "OUTAGE" ONE-TIME ACTION (Yes/No)

PROGRAMMATIC (Yes/No)

Exelon Generation Company, LLC (EGC) will complete the inspection of the Braidwood Unit 1 Auxiliary Feedwater tunnel classified as restricted access and deferred due to inaccessibility.

A1R17 Fall 2013 Yes No Exelon Generation Company, LLC (EGC) will complete the inspection of the Braidwood Unit 2 Auxiliary Feedwater tunnel classified as restricted access and deferred due to inaccessibility.

A2R17 Spring 2014 Yes No