RS-12-164, Company, Llc’S 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

Company, Llc’S 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

ML12332A303
Person / Time
Site:	LaSalle
Issue date:	11/27/2012
From:	Kaegi G Exelon Generation Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
RS-12-164
Download: ML12332A303 (51)

Text

10 CFR 50.54(f)

RS-12-164 November 27, 2012 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, MD 20852 LaSalle County Station, Units 1 and 2 Facility Operating License Nos. NPF-11 and NPF-18 NRC Docket Nos. 50-373 and 50-374

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 LaSalle County 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 LaSalle 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 LaSalle County 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 - LaSalle Units 1 and 2 NRC Project Manager, NRR - LaSalle 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 (walkdownsh 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 LaSalle County 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 LaSalle 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,

~9i7./¥ 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 LaSalle County 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 - LaSalle Units 1 and 2 NRC Project Manager, NRR - LaSalle 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 LaSalle County Station, Units 1 and 2 (47 pages)

FLOODINGWALKDOWNREPORT

INRESPONSETOTHE50.54(f)INFORMATIONREQUESTREGARDING NEARTERMTASKFORCERECOMMENDATION2.3:FLOODING

forthe

LASALLECOUNTYNUCLEARPOWERSTATION 2601North21stRoad,Marseilles,IL61341 FacilityOperatingLicenseNos.NPF11(Unit1)andNPF18(Unit2)

NRCDocketNos.STN50373(Unit1)and50374(Unit2)

ExelonGenerationCompany,LLC 300ExelonWay,KennettSquare,PA19348

Preparedby:

AMECEnvironmentandInfrastructure 502WestGermantownPike,Suite850,PlymouthMeeting,PA19462

November6,2012

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Contents Contents............................................................................................................................................................................. 2

1.

EXECUTIVE

SUMMARY

............................................................................................................................................... 3

2.

PURPOSE.................................................................................................................................................................... 4

a.

Background........................................................................................................................................................... 4

b.

SiteDescription.................................................................................................................................................... 5

c.

RequestedActions................................................................................................................................................ 7

d.

RequestedInformation........................................................................................................................................ 7

3.

METHODOLOGY......................................................................................................................................................... 8

a.

OverviewofNEI1207(WalkdownGuidance)..................................................................................................... 8

b.

ApplicationofNEI1207....................................................................................................................................... 9

c.

ReasonableSimulations..................................................................................................................................... 11

d.

WalkdownInspectionGuidance......................................................................................................................... 11

4.

RESULTS................................................................................................................................................................... 11

a.

RequestedInformationItem2(a)-DesignBasisFloodHazards....................................................................... 12 PMFontheIllinoisRiver.......................................................................................................................................... 12 PMPEventontheCoolingLakewithWaveRunUp................................................................................................ 12 LocalIntensePrecipitation(LIP)Analysis................................................................................................................. 13 OtherFloodingMechanisms.................................................................................................................................... 13 PMFConclusion....................................................................................................................................................... 14

b.

RequestedInformationItem2(b)-CLBProtectionandMitigationFeatures................................................... 14

c.

RequestedInformationItem2(c)-FloodWarningSystems............................................................................. 15

d.

RequestedInformationItem2(d)-FloodProtectionSystem/BarrierEffectiveness......................................... 15 AdditionalProtectionMeasures.............................................................................................................................. 20

e.

RequestedInformationItem2(e)-ImplementationofWalkdownProcess..................................................... 20

f.

RequestedInformationItem2(f)-FindingsandCorrectiveActionsTaken/Planned........................................ 22 ObservationsDesignatedthroughCAPasDeficientandCorrectiveActionsPlanned............................................. 22 OtherItemsAwaitingFinalDispositioninCAP........................................................................................................ 24 RestrictedAccessAreas........................................................................................................................................... 24 InaccessibleAreas.................................................................................................................................................... 24 UnanalyzedConditions............................................................................................................................................ 26

g.

RequestedInformationItem2(g)-Cliff-EdgeEffectsandAvailablePhysicalMargin..................................... 26

h.

RequestedInformationItem2(h)-Planned/NewlyInstalledFloodProtectionEnhancements....................... 26

5.

CONCLUSIONS.......................................................................................................................................................... 27

6.

REFERENCES............................................................................................................................................................. 46

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1. EXECUTIVE

SUMMARY

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, Section 50.54 (f) (10 CFR 50.54(f) or 50.54(f)) (Reference 3) which included Enclosure 4 of Reference 3. The NRC requested that licensees perform flood protection walkdowns to identify and addressplantspecificdegraded,nonconforming,orunanalyzedconditionsandcliffedgeeffects(through thecorrectiveactionprogram)andverifytheadequacyofmonitoringandmaintenanceprocedures.

ThisreportprovidestheinformationrequestedintheMarch12,50.54(f)letterforLaSalleCountyStation (LSCS); specifically, the information listed under the Requested Information section of Enclosure 4, paragraph2(athroughh).

LSCSsiteislocatedinthesoutheasternpartofLaSalleCountyinnorthcentralIllinois,6milessoutheastof Marseilles,Illinois,3mileswestofStateHighway170,and0.5milenorthoftheGrandRidgeMazonRoad (LaSalle County Highway 6). The Illinois River is located approximately 5 miles north of the site. The probable maximum flood (PMF) at LaSalle is based on a 24hour local intense precipitation (LIP) event directlyonthesite.ThemaximumfloodelevationsduetoanLIPeventatthesiteare710.41feetand 710.48meansealevel(MSL),basedonlocationattheplantsite.

LSCScurrentlicensingbasisreports,calculationsanddrawingswereobtainedthroughLSCSpersonneland Exelons Electronic Document Management System (EDMS). Those documents were compiled and reviewed to understand the flooding related current licensing basis (CLB), general plant layout and functionality,andtodevelopalistoffloodprotectionfeaturestobeevaluatedduringthewalkdown.

Flooding walkdowns were performed between August 10 and September 14, 2012, based on guidance provided in Nuclear Energy Institute (NEI) document NEI 1207 [Rev. 0A] (Reference 2). Observations capturedduringthewalkdownsweredocumentedonpapercopiesoftheWalkdownRecordFormprovided inAppendixBofNEI1207(Rev0A).Picturesweretakenofeachfloodprotectionfeatureandassociated deficiency,ifapplicable.SelectfeaturesweresurveyedtoassessAvailablePhysicalMargin(APM).

Onehundredeightyfive(185)featureswereincludedonthewalkdownlist.Allofthesefeatureswere considered incorporated passive. Thirty (30) features could not be immediately judged as acceptable duringthefloodingwalkdown.Thirtythree(33)featureswereinareasconsideredtoberestrictedaccess andweredeferredtooutageorwhentheareaswouldbeopened.Eight (8)features wereconsidered inaccessible.

Five(5)deficiencieswereidentifiedduringthewalkdown.Notethatthree(3)ofthesedeficiencieswerefor features not on the walkdown list, because they were originally surveyed for Available Physical Margin (APM)only.Two(2)penetrationsealswereobservedtobeinaconditionthatcouldnotbeimmediately judgedasacceptableandtheCorrectiveActionProgram(CAP)processdeterminedtheyweredeficiencies.

Three (3) exterior doors had thresholds that were identified as being lower than the calculated flood elevation.ThesethreedoorthresholdswereconsidereddeficientintheCAPprocess.Noconditionswere foundthatchallengedplantsafetyoroperability.

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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

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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. SiteDescription LSCS is located in the southeastern part of LaSalle County in north central Illinois, 6 miles southeast of Marseilles,Illinois,3mileswestofStateHighway170,and0.5milenorthoftheGrandRidgeMazonRoad (LaSalleCountyHighway6).TheIllinoisRiverislocatedapproximately5milesnorthofthesite.

TheLSCSsiteislocatedintheIllinoisRiverbasin,whichisdrainedbythemainstemoftheIllinoisRiverand itstributaries,includingthecanalsystemintheChicagoarea.TheIllinoisRiveristhelargesttributaryofthe MississippiRiverabovethemouthoftheMissouriRiver.Itflowsinawesterly,southwesterly,andsoutherly directionadistanceof273milestoitsconfluencewiththeMississippiRiver.

The natural drainage area of the Illinois River is 28,200 square miles, including 1,000 square miles in Wisconsinand3,200squaremilesinIndiana.DiversionsfromtheLakeMichiganwatershedbyreversalof theflowoftheChicagoandCalumetRiversincreasethenaturaldrainageareaoftheIllinoisRiverfrom 28,200squaremilesto29,010squaremiles.ThedrainageareaoftheIllinoisRiverneartheLSCSsiteis 7,640squaremiles.

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TheLSCSsitegeologyisdividedintoalargesoutherngentlyrollinguplandportioncontainingtheplant buildingsandcoolinglakeandasmallportiontothenorth,intheIllinoisRivervalley,containingtheintake works.Themaximumtopographicreliefbetweenthetwopartsisabout250feet.

TheLSCSsiteoccupiesapproximately3,060acres,ofwhich2,058acrescomprisethecoolinglake.The terrainaroundtheplantsiteisgentlyrolling,withgroundsurfaceelevationsvaryingfrom700feetto724 feetMSL.Naturaldrainageatthestationsiteisgenerallytowardthecoolinglake.

TheLSCSsiteisatwounitsite.Constructionbeganin1973forUnit1andin1972forUnit2.Units1and2 were licensed for commercial operation in 1982 and 1984, respectively. The plant grade and floor elevationsare710.00feetand710.50feetMSLrespectively.

PertheCLBdocumentation,threemainfloodingmechanismswereconsideredatLSCS:APMFwithwave runupontheIllinoisRiver,aprobablemaximumprecipitation(PMP)eventonthecoolinglakewithwave runup,andLIPdirectlyonthesite.

ThePMFelevationoftheIllinoisRiverplus40mphoverlandwindgeneratedwaverunupis522.5feetMSL, 188feetbelowtheplantgradeelevation.

ThePMFelevationonthecoolingpondincluding40mphoverlandwindgeneratedwindwaverunupis 705.6feetMSL,4.9feetbelowplantgradeelevation.

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ThePMFmaximumfloodelevationduetoLIPlistedintheUpdatedFinalSafetyAnalysisReport(UFSAR)is 710.41feetMSL.APMFfloodelevationduetoLIPof710.48feetMSLwascomputedinthenortheast portionofZoneIinDesignCalculationS66,butthatelevationhasnotbeenincorporatedintotheUFSAR.

ThisissuewascapturedinanissuereportintheCorrectiveActionProgramasdescribedlaterinthisreport intheResultssection,subsectionf.Therefore,themaximumfloodelevationof710.48feetMSLcomputed inCalculationS66wasusedforthreefeaturesinthenortheastportionoftheplant.Thefloodingelevation of710.41feetMSLdocumentedintheUFSARwasusedtoevaluatetheremainderofthefeatures.

TheCLBdocumentationstatesthatsincetherearenolargebodiesofwaterintheimmediatevicinityofthe site,stormsurges,seiches,andtsunamifloodsarenotrelevant.FailureofupstreamdamsontheIllinois River or its tributaries is also not relevant, since these are low dams for navigation and hydropower generation,andtheirfailurewouldnotexceedtheseverityofthePMFontheIllinoisRiver.Failureofthe coolinglakedikeswouldnotcausefloodingoftheplantduetothenaturaltopographyaroundthesite.

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.

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. ofReference3alsostates,Ifanyconditionidentifiedduringthewalkdownactivitiesrepresents adegraded,nonconforming,orunanalyzedcondition(i.e.noncompliancewiththecurrentlicensingbasis) foranSSC,describeactionsthatweretakenorareplannedtoaddresstheconditionusingtheguidancein Reference 6, including entering the condition in the corrective action program. Reporting requirements pursuantto10CFR50.72shouldalsobeconsidered.

d. RequestedInformation PerEnclosure4ofReference3,

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

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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.

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.SeenoteinSection12regardingtheNRCschangein 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)

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o DesignBases o Inaccessible o RestrictedAccess o Deficiency o FloodProtectionFeatures o ReasonableSimulation o VisualInspection o CliffEdgeEffects o AvailablePhysicalMargin 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 Exelonsapproachtothefloodingwalkdownsincludedthreephases:

Phase1-Preparation,Training,DataGathering,andScoping

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Phase2-Inspections Phase3-FinalReporting ThepurposeofPhase1wastoobtainaclearunderstandingofthesitesfloodmitigationstrategy;develop scope, methodology, and acceptance criteria for the walkdowns; and logistical planning. The following activitieswereperformedduringPhase1:

Datagathering(CLBdocumentsandplantdrawings);

Sitevisittopreviewfeaturesandplantconditions; DesktopreviewofCLBdocumentstoidentifyanddescribetheCLBfloodhazard; DesktopreviewofCLBdocumentstoidentifyanddescribefloodprotection/mitigationstrategy; DevelopmentofWalkdownList; DevelopmentofWalkdownmethodologyandacceptancecriteria; Logisticsandstrategyplanning;and PreparationofWalkdownPackages.

ThepurposeofPhase2wastoexecutetheFloodingWalkdownforLSCS,whichincluded:

Visualinspection; CollectAPMsurveydata;and Documentationofobservations.

TheFloodingWalkdownactivitiesforLSCSinvolvedvisualinspectionsofthefollowingfeaturetypes:

1. Sitedrainageplan/flowpaths

2. Exteriorwallsbelowgrade

3. Exteriorwallpenetrationsealsbelowgrade

4. Roofs

5. BasementFloorSlabs

6. Groundfloorexterioraccessdoors,openings,andremovablewallpanelthresholds-APMsurvey only Allvisualinspectionsoffeatureswererecordedinthefieldtodocumentconditionassessments.Foreach observation,thefeaturelocation,photographswithdescriptions,andgeneralobservationswererecorded.

Thefielddatawasuploadedtoadatabase.ThedatabasewasusedtogeneratetheWalkdownRecordForm foreachfeature/procedure.TheWalkdownRecordFormprovidedinNEI1207(Rev.0A),AppendixBwas usedtodocumentthecollectedfielddataandresultsoftheFloodingWalkdownforboththefielddata collectionandthefinalforminsupportofthisreport.

Inaddition,groundflooraccessdoorthresholds,removablewallpanels,andtheradioactivewasteloading dockweresurveyedtodeterminetheirfinishfloorelevations.ThisinformationwasalsousedfortheAPM analysis.

This Walkdown Report was developed to document the methodology and findings of the Flooding Walkdowns.TheWalkdownReportwaspreparedinaccordancewiththetemplateprovidedinNEI1207 (Rev.0A),AppendixD.

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c. ReasonableSimulations Flood mitigation procedures are not relied upon for flood protection at LSCS; therefore, reasonable simulationsarenotpartofthisfloodingwalkdown.

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

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

ThreemainfloodingmechanismswereconsideredintheLSCSUFSARRevision19:Aprobablemaximum flood(PMF)plus40mphoverlandwindgeneratedwaverunupontheIllinoisRiver,aprobablemaximum precipitation(PMP)eventonthecoolinglakewithwaverunup,andanLIPrainfalleventdirectlyonthe site.

PMFontheIllinoisRiver Thestationis"floodproof"or"dry"withregardtoapostulatedPMFintheIllinoisRiver,sincetheplant floor(elevation710.50feetMSL)is188feethigherthanthePMFpluswaverunup(elevationof522.5feet MSL),whichincludesthemaximum(1%)wavecharacteristicsofsustained40mphoverlandwindsonthe probablemaximumwaterlevel.

TheU.S.ArmyCorpsofEngineers(USACE)extrapolatedaPMFdischargeof316,000cubicfeetpersecond (cfs)atLSCScorrespondingtoadrainageareaof7,640squaremilesfromPMFdischargescomputedat gaging stations at Meredosia, Beardstown, and Peoria, Illinois along the Illinois River. Allowing for the effectofurbanization,aconservativemaximumdischargeof350,000cfswasusedforthePMFanalysis.

The PMF discharge was routed through crosssection geometry developed from topographic data and soundings of the lllinois River channel obtained by the USACE. Using the slopearea method, a PMF StillwaterelevationintheIllinoisRiverinthevicinityofLSCSwasestimatedtobe521.8feetMSL.Wind wavecharacteristicscorrespondingto40milesperhouroverlandwindswereinvestigatedyieldingaheight ofmaximumwaverunupof0.7feet.AddingthisvaluetothePMFStillwaterlevelof521.8feetMSLyielded aprobablemaximumwaverunupelevationof522.5feetMSL,whichis188feetbelowtheplantfloor elevationof710.50feetMSL.ApostulatedPMFontheIllinoisRiver,therefore,doesnotaffectanysafety relatedfacility.

PMPEventontheCoolingLakewithWaveRunUp A PMF with antecedent standard project flood (SPF) was routed through the lake using the U.S. Army HydrologicEngineeringCenter'scomputerprogram22J2L210,"SpillwayRatingandFloodRouting",1966.

Inputstotheprogramconsistoftheelevationcapacitydataderivedfromtopographicmapsofthearea.

Theinitialwaterlevelusedforroutingisthenormallakelevelof700.0feetMSL.Theprogramcalculated theoutflowfromthelakefortheauxiliaryspillway,whichhasacrestelevationof702.5feetMSLandfor theservicespillway,whichhasacrestelevationof697.75feetMSL.Theservicespillwaydirectslakewater intotheblowdownlinetotheIllinoisRiver.ThemaximumlakelevelcorrespondingtotheSPFis701.6feet MSL,whichislowerthantheauxiliaryspillwaycrestelevation.

WhentheSPFisfollowedbythePMF,withthreerainlessdaysbetweenthestandardprojectstorm(SPS) andthePMP,thelakelevelvariesfromamaximumof701.6feetMSLduringSPFto701.0feetMSLbefore theriseduetoPMF,andtoamaximumstillwaterelevationof704.3feetMSLduringPMF.

Maximumwaverunupassociatedwith40mphoverlandwindscoincidentwiththePMFattheplantsiteis computedtobe1.3feet.Thewaverunupelevationobtainedbyaddingthewaverunuptotheprobable maximumwaterlevelis705.6feetMSL.Sincetheplantgradeandfloorelevationsare710.00feetand

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710.50feetMSLrespectively,thereisnofloodingattheplantdueto40mphoverlandwindscoincident withtheprobablemaximumwaterlevelinthelake.

LocalIntensePrecipitation(LIP)Analysis The24hourPMPatthesiteis32.1inches.Toroutetherunofffromtherainfallovertheplantarea,the24 hourPMPisdividedintosmallertimeintervals.Forexample,14.8inchesofprecipitationispostulatedto fallinthefirsthourofthestorm.Conservatively,infiltrationlosseswereconsiderednegligible,thesite drainagesystemwasassumednotfunctioning,andtheprecipitationfallingondifferentportionsofthesite areawasassumedtoreachtheperipheralroadssimultaneously.Therationalformulawasusedtoestimate peakrunoff.

Theplantareawasdividedintotwozones,ZoneIandZoneII.Themaximumrunofffromeachofthezones was routed over the peripheral roads and railroads to obtain the maximum water surface elevation upstreamoftheperipheralroadsandrailroads.Culvertsrunningundertheseroadsandrailroadswere assumedtobefullyblocked.

ThepeakrunoffforZoneIwascalculatedtobe1,065cfs.Thebackwatercalculationsbeginningfromthe peripheralroadsandrailroadsyieldedawatersurfaceelevationof710.18feetMSLupstreamofthenorth southaccessroadandamaximumwatersurfaceelevationof710.37feetMSLneartheeastsideofthe plantbuildinginZoneI.

For Zone II, a stepbackwater analysis was performed using the U.S. Corps of Engineers Hydrologic EngineeringCentersRiverAnalysisSystem(HECRAS)computerprogram.ThepeakdischargeatTrackNo.1 is692.5cfs.BasedontheUFSAR,thebackwatermodelresultsinawatersurfaceelevationof710.16feet MSLatTrackNo.1andlessthan710.41feetMSLadjacenttotheeastsideoftheplant.

TheUFSARreportsthePMPmaximumfloodelevationof710.41feetMSL.Thatfloodelevationwasused forallbutthreefeatures.APMFfloodelevationof710.48feetMSLwascomputedinthenortheastportion ofZoneIinDesignCalculationS66,butthatelevationhasnotbeenincorporatedintotheUFSAR.Thisissue isdiscussedlaterinthisreportintheResultssection,subsectionf.Threefeatures(exterioraccessdoorsD 164,D20andD508)areinthevicinityofwhere710.48feetMSLwascomputed,andaretheonlyfeatures thataremateriallyaffectedbythediscrepancy.Therefore,elevation710.48feetMSLwasusedastheflood elevationtoevaluatethosedoors.

OtherFloodingMechanisms TheCLBdocumentationstatesthatsincetherearenolargebodiesofwaterintheimmediatevicinityofthe site,stormsurges,seiches,andtsunamifloodsarenotrelevant.FailureofupstreamdamsontheIllinois River or its tributaries is also not relevant, since these are low dams for navigation and hydropower generation,andtheirfailurewouldnotexceedtheseverityofthePMFontheIllinoisRiver.Failureofthe coolinglakedikeswouldnotcausefloodingoftheplantduetothenaturaltopographyaroundthesite.

Section2.4.13.5oftheLSCSUFSARstatesthatthegroundwaterlevelassumedforcalculationofhydrostatic loadingonthepowerplantfoundationsiselevation700.00feetMSL,whichisequivalenttothedesign coolinglakelevel.Thedesigngroundwaterlevelisbasedontheassumptionthatgranularfillaroundthe plantfoundationswillbehydraulicallyconnectedwiththecoolinglakethroughthegranularfillaroundthe intakepipelines.Thegroundwaterlevelinthegranularfillaroundtheplantfoundationswouldreflectthe coolinglakelevel.

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TheUFSARstatesthatthegranularfillaroundtheplantfoundationsiscoveredwith20feetofessentially impermeable,compactedclay.Inaddition,thesurroundingclayeytillisalsoessentiallyimpermeable.Due tothecompactedclaycoverandclayeytill,itisexpectedthatinfiltrationofprecipitationandgroundwater seepagewouldlikelybeminimal.

PMFConclusion Forthefloodingwalkdowns,thecriticalCLBhazardconsideredwastheLIP.Themaximumfloodelevation of710.48feetMSLcomputedinCalculationS66wasusedforthreefeaturesinthenortheastportionofthe plant. The flooding elevation of 710.41 feet MSL documented in the UFSAR was used to evaluate the remainderofthefeatures.

b. RequestedInformationItem2(b)-CLBProtectionandMitigationFeatures Describeprotectionandmitigationfeaturesthatareconsideredinthelicensingbasisevaluationtoprotect againstexternalingressofwaterintoSSCsimportanttosafety.

The flood protection features credited in the CLB for LSCS are considered incorporated passive. The featuresarelocatedintheAuxiliary,DieselGenerator,Reactor,Turbine,Offgas,LakeScreenHouseand RadioactiveWasteBuildings.Thefeaturesinclude:

1. Sitedrainageplan/flowpaths

2. ExteriorwallsbelowgradeExteriorwallstogradelevelaresealedwithawaterproofmembrane.

Exteriorconstructionjointsaresealedwithwaterstopstogradelevel

3. Exteriorwallpenetrationsealsbelowgrade

4. Roofs

5. BasementFloorSlabs

6. Groundfloorexterioraccessdoors,openings,andremovablewallpanelthresholds-Performed surveyforAPManalysisonly The PMF flood elevation is based on a 24hour rain event; however the CLB does not identify flood duration.Therefore,thedurationofthefloodingwasnotconsideredforthisevaluation.

Exteriorwallsandpenetrationsealsaredesignedtoprotectagainstgroundwateringress.DBDLSM11Rev Bstatesthatexternalwallsbelowgradeelevationarerequiredtobecoveredwithawaterproofmembrane.

Inaddition,allexteriorconstructionjointsaresealedwithwaterstopstogradelevelandpipepenetrations inexteriorwallsarerequiredtohavewatertightpenetrationsleeves.TheCLBdoesnotspecificallycredit floor slabs for providing protection from groundwater ingress, although they are designed to resist full hydrostaticupliftpressures.

TheLakeScreenHouseisaffectedbystaticanddynamicconsequencesofwaveactivity.Thewallsofthe Lake Screen House are designed to withstand hydrodynamic forces caused by wind wave runup superimposedonhydrostaticforces.TheLakeScreenHousewallswereincludedinthewalkdownlist.

ThefloodingCLBdoesnotspecifyplantconfigurationsduringcertainmodesofoperation.Therefore,all modesofoperationwereconsideredduringthewalkdown.

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FloodmitigationproceduresarenotrelieduponforfloodprotectionatLSCS,andtherearenowarning systemsforweatherconditionsorfloodlevelspresentattheplant.

DuringanLIP,shallowfloodingduetosheetflowcouldoccurnorthandwestoftheplantbuildings.Surface conditionscouldbecomesoft(i.e.muddy)wheregroundcoverisgrassandsoil.Bothoftheseconditions couldmakemovingequipmentandfoottrafficchallenging.However,becauseproceduresarenotpartof the LSCS CLB, and the flood protection strategy consists of incorporated passive features only, these adverseconditionshavenoimpactontheperformanceoffloodprotectionfeatures.

c. RequestedInformationItem2(c)-FloodWarningSystems Describeanywarningsystemstodetectthepresenceofwaterinroomsimportanttosafety.

Therearenosystemsinplacecreditedwithdetectingtheoccurrenceoforprovidingwarningintheevent ofanexternalfloodevent.Thisisinagreementwiththerequirementsofthecurrentfloodinglicensing basis.

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,toprovidemore specificcriteriaforjudgingacceptance.Allobservationsthatcouldnotbeimmediatelyjudgedasacceptable were entered into the sites Corrective Action Program (CAP) where a subsequent evaluation of the observationcouldbemade.

ThepurposeoftheFloodingWalkdownswastodetermineiftheplantscreditedexternalfloodprotection featuresconformtotheLSCSCLBandmeettheacceptancecriteriaoutlinedinSection6ofNEI1207and the Supplemental Walkdown Inspection Guidance. The CLB credits plant exterior walls and wall penetrationsealsbelowgradeforprovidingprotectionagainstexternalfloodingingressintotheplant.Site topographyandabovegrounddrainagepathwaysarecreditedforprovidingdrainageforthesite.TheCLB alsocreditsroofsofSeismicCategoryIstructuresforsupportingloadsthatequatetoamaximumdepthof 16inchesofwaterstoredontheroofsurface.Finally,theCLBcreditstheLakeScreenHouseexteriorwalls exposedtothelakeforwithstandingstaticanddynamicloadscausedbywaverunupfromthecooling pond.InadditiontothefloodprotectionfeaturesdiscussedintheCLB,basementfloorslabswerealso walkeddown.Theacceptancecriteriaforeachofthefloodprotectionfeaturetypesareasfollows:

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SiteElevationsandTopography o Verify the current site topography (i.e. contours, slopes, and grades) appears to be consistent with the topography assumed in the CLB flood evaluation, based on field observations.

o Verify that the plant configuration with regard to impervious areas assumed in the CLB evaluationhasnotchanged.

o Verify that the site drainage system configuration appears to be consistent with CLB evaluation.

o Verifythattherearenoaddedstructures,securitybarriers,fences,etc.,notshownonthe designdrawingsusedintheCLBfloodingevaluationthatcouldaffectsitedrainage.

DrainagePathways(SwalesandChannels) o Verifythefeatureisinplaceandconfiguredasdesigned.

o Visually inspect the material condition to determine if there is any damage that might preventthefeaturefromperformingitsfloodprotectionfunction.

o Verifythattheplantdrainageswalesarefreeofobstructionsthatcouldpreventthefeature from performing the flood protection function and controls are in place to assure they remainfreefromobstruction.

ConcreteExteriorWalls o Verifythatthestructure isinplaceandinaccordancewithitsdesign configuration,per plantdocuments.Thelevelofverificationherewouldbetodeterminethatthereareno openingsthatarenotshownonthedrawingsandtheopeningsareofthesameshapeand location as shown on the design drawings. If a wall structure, perform physical measurementtoconfirmtherequiredheight.Theminimumrequiredheightmustbemet withnoallowancefordimensionaltolerance.

o Visuallyinspectallexteriorexposedsurfacesbelowtheanalyzedmaximumfloodheightfor significantindicationsofstructuraldegradationoranyopeningsthatmightpermitflooding oftheinteriorspaces.

o Visiblepenetrationsaresealed.

o Requiredreliefpathsareinplaceandunobstructed.

o Nosignsofwateringressoninteriorsurfaces(e.g.calcification,staining,etc.).

o Ifconditionswillnotallowcloseexamination,useofbinocularsispermittedif100%ofthe surfaceareabelowthemaximumfloodheightcanbeinspectedinamannersufficientto meettheintentofthisreview;alternatively,acameraonastickcanbeemployedfor evaluation.

o Noapparentdegradationinstructuralmembersthatchallengestheirabilitytowithstand forces from flooding, i.e. reinforced concrete, concrete block or steel barriers, such as surfacecracksgreaterthan0.04inchinwidth.

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o Concrete structures should not show water stains/stalactites emanating from their surfaces.

o Surfaces of the structure/building that are buried are considered inaccessible and not subjecttoinspection.Avisualinspectionofinteriorsurfaceisacceptable,iftheexterior surfaceisinaccessible.Inaddition,thebaseofstructuresshouldbeinspectedforevidence ofscouringorunderminingthatmayhaveoccurredduringprevioushighwaterevents.

o IfaPM/surveillanceexiststhatinspectsthestructure,thenitisnotnecessarytospecifically inspect individual barriers for this review (although the surface (e.g., wall), in accessible areas, must still be visually inspected for any unexpected conditions). If credit is being takenforaPM,thenidentifythePMnumberinthewalkdownrecords.ThePMshouldbe reviewedforadequacyperNEI1207.

WallPenetrationSeals o Perform a visual inspection of credited wall, ceiling, and floor penetration seals for indicationsofdegradationthatwouldallowexternalwateringressintothefloodprotected area. Conditions that should be recorded include (but are not limited to) damage, undocumentedopeningsorholes(suchasthoseduetoabandonedequipment),etc.

o Thecreditedside(s)(surface)ofasealmustbeinspected.Forexample,ifthesideofawall penetration seal that is credited for flood protection is examined and found to be acceptable,theothersideofthesealdoesnotrequireexamination.

o Visiblepenetrationsaresealedandtherearenovisiblegapsthroughwallholes.

o Penetrationsleeves,linkseals,piping,andconduitshouldhaveanabsenceofcorrosionon theexposedsteelsurface.

o Conduitsealmaterialshouldhaveanabsenceofwaterstainsbelowthepenetrations.

o Material should appear to be as indicated in plant documents and in generally good condition.

PipingandCableVaultsandTunnels,ElectricalCableConduit o Wateringressintotunnels,vaults,andcableconduitisnota concernin the shortterm unlesstherearecomponentsinthesestructureswithanactivefloodprotectionfunction thatmightbedamagedbysubmergence.

o Provide reasonable assurance that these features will not become pathways for water (surfaceorgroundwater)intoSSCsprotectedfromflooding.SeeNEI1207regardingthe evaluation of features designated as inaccessible. Reasonable assurance that these featuresarenotreceivingandconveyingwatertoprotectedSSCscanbedemonstratedby reviewing plant/construction drawings and specifications. If visible, internal seals should also be inspected; see previous discussion on seal inspection guidance. The following factorscanbeconsideredinmakingareasonableassurancedetermination:

Conduit/pipematerialtype; Constructionmethods; Typeofjoints;

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Elapsedtimesinceinstallation; Conditionssurroundingconduit/pipe(saturatedsoil,acidity,etc.);

Information regarding durability of conduit/pipe material and associated joints;and Signsofleakageinsidetheplantbuilding,particularlyattheterminuspoint.

o Signs of leakage and inspection results for internal seals should be captured on the Walkdown Record Form for the associated penetration or wall feature. The Walkdown RecordFormshouldalsoincludeanattachmentthatcontainsthebasisforthereasonable assurancedetermination,discussedabove.

o Visuallyinspectallsealsorotherdevicesthatarecreditedtopreventwaterintrusionintoa spacethatcontainssafetyrelatedequipmentorequipmentcreditedforfloodprotection duringafloodingevent.

o Determine if there is any damage that would prevent the seals or other devices from performingtheirfloodprotectionfunction.Seepreviouslylistedsupplementalguidancefor Wall,Ceiling,andFloorSealsforadditionalguidanceonsealinspection.

Roofs o Confirm that parapet heights do not exceed 1 foot, 4 inches on Seismic Category I structures.

o Confirm that roof feature openings have lip heights higher than the parapets or the opening can accommodate water without water entering the plant, or roof drains are capableofkeepingtherainfromenteringtheopening.

o Visually inspect all exterior exposed surfaces of the roof for significant indications of structuraldegradationoranyopeningsthatmightpermitfloodingoftheinteriorspaces.

o Confirmthatvisiblepenetrationsaresealed.

o Builtupsurfacesoftheroofthatarecoveredwithaggregateballast,suchasslagorgravel, areconsideredinaccessibleandnotsubjecttoinspection.

BasementFloorSlabs o Nosignsofdegradation.

o Nospalling,scaling,orcrackingofconcretesurfaces.

LakeScreenHouseWalls o Verifythatthestructure isinplaceandinaccordancewithitsdesign configuration,per plantdocuments.

o Thewallsshouldbeinspectedforevidenceofstructuraldamagethatwouldpreventthe wallsfromperformingtheirdesignfunctionofresistingthelakePMFwithwaverunup.

GroundFloorDoorThresholds,RemovableWallPanelsandRadioactiveWasteLoadingDockWalls o ThesefeaturesareevaluatedforAPM.

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Thevisualinspectionsrevealedthatthefloodprotectionfeaturesmettheacceptancecriteriaandwere consideredacceptablewiththeexceptionoftheitemsenteredintotheCAPandarelistedinTables3and4 of Section 5 of this report. Table 2 of Section 5 lists the flood protection features determined to be acceptableduringthevisualinspections.

Asummaryofthefloodprotectionfeaturesthatweredeterminedtobeacceptableareasfollows:

Basementfloorslabsdidnothavesignificantsurfacecracking,materialdegradationorshowsigns of water intrusion. Basement floor slabs were considered to be acceptable and capable of performingtheirdesignfloodprotectionfunction.

Exteriorwallscreditedforprovidingfloodprotectiondidnotshowsignsofmaterialdegradation, spallingorsignificantcracking.Exteriorwallsdidnotshowsignsofwaterintrusionsuchasstaining, calcification or stalactites. Exterior walls were considered to be acceptable and capable of performingtheirdesignfloodprotectionfunction.

Penetration seals did not show signs of material degradation that would allow external water ingress.Penetrationsleeves,pipingandconduitmaterialdidnotshowcorrosion.Conduitsealsdid nothavewaterstainsbelowthepenetrations.Materialandpenetrationlocationswereconsistent withplantdesigndrawings.Basedonthoseobservations,thepenetrationsealswereconsideredto beacceptableandcapableofperformingtheirdesignfloodprotectionfunction.

Safetyrelatedroofparapetwallswereobservedtobelessthan16inchesabovetheroofsurface.It was determined water had no ingress paths to the plant through penetrations or deteriorated roofing.Roofsweredeterminedtobecapableofperformingtheirdesignfloodprotectionfunction.

LakeScreenHousewallsexposedtothelakewereplacedinaccordancewithdesignconfiguration anddidnotshowsignsofstructuraldamage.Basedonobservations,theLakeScreenHousewalls weredeterminedtobecapableofperformingtheirdesignfloodprotectionfunction.

Siteelevations,topography,anddrainagepathwayswerefoundtobeinaccordancetositeanalyses andassumptions.Nomajormodificationswerefoundthatwouldaffecttheanalyses.

The LSCS flood protection strategy consists of incorporated passive features only and no operator procedures.Therefore,additionaladversesiteandweatherconditionsdonotimpacttheperformanceof thefloodprotectionfeaturesandthesitesfloodprotectionplan.

SincepenetrationsinbasementfloorslabsarenotspecificallycreditedintheCLB,theywerenotwalked downindividually.Observationsonpenetrationsinbasementfloorslabsweremadeduringthefloorslab walkdowns.Onlytwolocationsofthefloorslabwerenotimmediatelyjudgedasacceptableduringthe walkdownduetoobservedcrackingintheslabandminorapparentgroundwaterinleakage.Neitherofthe inleakagelocationswasduetodegradedconditionsoforaroundpenetrations.

LaSallehasfourelectricalconduitruns(Conduit1,Conduit2,Conduit3andConduit4)thatentertheplant belowthePMFfloodelevationof710.41feetMSL.Noneofthefourconduitrunstieintomanholes.The conduitsareatthefollowinglocations:

Conduit1-Unit2HeaterBayonYlinebetween18and19fromelevations682.25feetMSLto 680.75feetMSL Conduit2-Unit1HeaterBayonYlinebetween12and13fromelevations682.25feetMSLto 680.75feetMSL

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Conduit3-OffGasFilterBuildingon14linebetweenAbandAcfromelevations705.40feetMSL to703.90feetMSL Conduit4-OffGasFilterBuildingon11linebetweenAandAbfromelevations705.50feetMSLto 707.50feetMSL.

Conduits1,2and4arecontinuousandnotopentogroundwaterfromtheplantexteriorwallstotheirend point which is above the flood elevation based on review of electrical design drawings. Conduit 3 (penetratingbelowthefloodelevationat14lineoftheOffGasBuilding)connectstoadrainpointforduct runsoutsideoftheoffgasbuildingbeforeextendingbackintothereactorbuilding.Insidethedrainpoint, theconduitshavedrainageslotscutintothemcreatingapotentialflowpathforwaterintotheoffgas building.AwalkdownoftheConduit3penetrationattheOffGas14lineexteriorwallconfirmedthatthe conduitshadrecentlybeenresealed,preventingfloodwaterfromenteringtheplant.

Allotherelectricalconduitrunsenterinsidetheplantabove710.50feetMSL,soifamanholeflooded, waterwouldnotgetintotheplantfromthoseconduitruns.Theseconduitsarealsodesignedtohaveseals attheopeningsoftheconduitseitherattheendontheexteriorsideoftheplantorattheendontheinside oftheplant.

AdditionalProtectionMeasures Thebasementfloorslabsofthemainpowerblockbuildingsincludeanetworkoffloordrainsandsump pumps(primaryandbackup),whichcouldroutefloodwaterawayfromsafetyrelatedequipmentinthe event of a beyonddesign basis flood. The primary function of these drains and pumps is to provide protectionfrominternalflooding,butwouldalsobeavailabletoroutewaterfromanexternalsource.As thesefeaturesarenotcreditedforprovidingfloodprotection,ageneralobservationwasmadeandthey appearedtobeingoodworkingorder.

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.

Flooding walkdowns were performed using guidance provided in NEI 1207 (Rev. 0A) Guidelines for PerformingVerificationWalkdownsofPlantFloodProtectionFeatures.

ThemembersoftheWalkdownteamwereselectedtoensurethattheteamincludedindividualswhoare experienced in conducting visual inspections of plant structures, systems and components and flood protectionfeatures.TheAMECteamfortheLSCSFloodingWalkdownincludedaSeniorWaterResources Engineer,AJuniorWaterResourcesEngineer,aSeniorElectricalEngineer,andaJuniorStructuralEngineer.

Bothwaterresourcesengineersarefloodingspecialistsandhavesignificantexperiencewithinspections andevaluationsoffloodprotectionfeatures.Theremainingtwoengineersareexperiencedinconducting visual inspection of plant SSCs. The Exelon personnel involved with the walkdowns were two Civil/Structural Engineers and Project Management professionals with plant knowledge and plant MaintenancePersonnelthatprovidedlogisticalsupporttotheWalkdownteams.

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EachAMECteammembercompletedExelonsWalkdownTraining,NuclearGenerationEmployeeTraining (NGET),andNANTeLsgenericverificationwalkdownsofplantfloodprotectionfeaturescourse,including the NANTeL exam. The two Exelon Civil/Structural engineers also completed the NANTeL generic verificationwalkdownofplantfloodprotectionfeaturescourseandtheNANTeLexam.Inpreparationfor thewalkdown,theteammembersreviewedandbecamefamiliarwiththematerialsandcontentofNEI12 07 (Rev. 0A); and they also became knowledgeable of the sites current flooding licensing basis and operatingproceduresbythoroughlyreviewingthemduringthewalkdownplanningphaseoftheproject.

Generally,twoteamsofthreepersonswereutilizedtoperformthewalkdowns.Twopersonsineachgroup were familiar with the plants flooding design basis; were specialists in either water, civil, structural or electrical engineering; were prepared for flooding walkdowns through training developed by the NEI FukushimaFloodingTaskForce;andpassedtheNANTeLtrainingandexamination.Thethirdmemberof thewalkdownteamwasaplantspecialistfamiliarwithoperations,configurationsandthelocationofsafety relatedplantstructures,systemsandcomponents.Maintenancepersonnelaccompaniedthewalkdown teamswhennecessarytoprovideadditionallogisticalsupport.Wherespecificknowledgewasnecessaryto inspectafloodprotectionfeature,atleastonememberofthewalkdownteamhadtheabilitytoevaluate theacceptabilityofthefeaturecreditedwithprovidingfloodprotecton.

Theexceptiontohavingagroupofthreepersonnelperformthewalkdownwaswhenafeaturewasina locked high radiation area. To limit dose and potential contamination, generally one NANTeL trained specialist, with one other individual with plant knowledge, entered the locked high radiation area and performedthewalkdown.

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 radiation protection personnel when entering highradiation areas. Subjects discussed in highradiation prejob briefs included, but were not limited to, tasks required to complete the job, time required to completethetasks,doseratesurveys,maximumdoseratesandtotalallowabledose.

Acombinationofladder,cameraonastick,andscaffoldingwereusedtoperformvisualinspectionon floodprotectionfeaturesthatwerenotaccessiblefromtheplantfloor.Whenacameraonastickwas used,theplantspecialistextendedthecameraonasticktoapositionwheretheconditionofthefeature could be fully inspected by the NANTeL trained personnel through a view finder screen. Pictures were capturedfromthecameraonastick.

Concretewallswereinspectedusingbinocularswhereappropriate.Wallcrackwidthsweremeasuredusing crackwidthgaugecards.

ObservationscapturedduringthewalkdownsweredocumentedonpapercopiesoftheWalkdownRecord Form provided in Appendix B of NEI 1207 (Rev 0A). Pictures were taken of each penetration and of deficienciesonfloorslabsandwalls.

Adailyprojectreportwasgeneratedattheendofeachworkdaydocumentingthefollowing:

IndustrialSafety/FirstAid RadiologicalInformation ALARAInformation

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ProductionPerformance DeficienciesIdentified OperabilityIssuesIdentified GeneralProblems IssueReports(inCAP)

ItemsRequiringFurtherReview LessonsLearned ObservationsnotimmediatelyjudgedasacceptablewerereportedtoExelonpersonnelimmediatelyand IssueReportswereenteredintheCAP,asnecessary.

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

One hundred eightyfive (185)floodprotectionfeatureswereonthewalkdownlist.Accessiblefeatures wereinspectedtodeterminetheircompliancewithacceptancecriteriaprovidedinNEI1207(Rev.0A).

One hundred twelve (112) flood protection features were immediately determined as acceptable and capable of performing the designed flood protection function. Those features are listed in Table 2 of Section5.

Thirty(30)featureswereobservedtobeinaconditionthatcouldnotbeimmediatelyjudgedasacceptable butthroughtheCAPweredeterminednottobedeficiencies.Asummaryofthosefeaturesbyfeaturetype areasfollows:

Five(5)exteriorwalls Twentyone(21)penetrationseals Two(2)floorslabs Two(2)roofs Acompletelistofthosefeatures,observations,issuereportnumbersandresolutionsareprovidedinTable 3ofSection5.

ObservationsDesignatedthroughCAPasDeficientandCorrectiveActionsPlanned Two(2)penetrationsealsandfour(4)exteriordoorswereobservedtobeinaconditionthatcouldnotbe immediatelyjudgedasacceptableandduringtheCAPprocessweredeterminedtobedeficiencies.Note thatfortheexteriordoors,thedeficienciesarereportedasthree,becausetwodoorsareconsideredtobe thesamedeficiencyandwerewritteninthesameIssueReportinCAP.Additionally,notethatthesethree (3) deficiencies (four (4) door thresholds) were not on the walkdown list, because they were originally

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surveyed for Available Physical Margin (APM) only. The doors are D20 (Reactor Building secondary containmentmissiledoor-rail#2)andD164(U2TBtrackwaydoor,rail#3)inZoneI,D479(Unit1Diesel GeneratorCorridordoor)inZoneII,andD508(Unit2DieselGeneratorCorridordoor)inZoneI.The penetrations were 1TB1144 in the Unit 1 Turbine Building Makeup Demineralizer (MUDS) room and GenericCastIron2intheUnit1TurbineBuildingTubePullArea.

Penetration1TB1144islocatedintheUnit1TurbineBuildingMUDSroomatelevation705.83feetMSLon column 1 between rows V and W. The pipe through penetration 1TB1144 appeared to have shifted, separatingthesealcoverfromthesleevecreatingagapapproximately2to3incheswide.Waterstains wereobservedonthewallbelowthepenetrationandasmallamountofpuddlingwaterwasobservedon thefloor.Thesleevecouldprovideapathwayforwatertoentertheplant.Thevolumeofwaterthatcould enterthesitewouldbelimitedbythesoiloutsideofthepenetration.Inaddition,anywaterenteringthe buildingwouldberemovedbythesumppumpsintheMUDSroom.TheMUDSroomdoesnotcontainany safety related equipment. This condition was entered into the sites CAP through Issue Report (IR) 1401068,andthecorrectiveactionistorepairtheseal.

GenericCastIron2islocatedintheUnit1TurbineBuildingTubePullPit.Thecastironpipetransports waterforaneyewash.Thepenetrationdidnothaveapenetrationsealandthereforecouldpotentially provideapathwayforwaterinflow.Thevolumeofwaterthatcouldenterthesitewouldbelimitedbythe soiloutsideofthepenetration.Inaddition,anywaterenteringthebuildingwouldberoutedtosumpsby floordrainsuponenteringtheplant.ThisconditionwasenteredintothesitesCAPthroughIR1401463, andthecorrectiveactionistorepair/provideaseal.

ThedoorD479thresholdelevationwassurveyedtobe710.35feetMSL.ThethresholdelevationofdoorD 479is0.06feetbelowtheCLBfloodelevationof710.41feetMSLand0.02feetbelowthecalculatedflood elevationforZoneIIof710.37feetMSL.APMPfloodeventcouldbepostulatedtoenterthebuildings throughD479.However,thereisan18inchtallfloodbarrierjustinsidethedoormadeofsheetmetaland steel angles that is anchored to the floor and caulked. This condition was entered into the sites CAP throughIR1416084.Thecalculationwasreviewed,anditisapparentthereisadditionalmargin.Therefore, thecorrectiveactionistorevisetheZoneIIcalculationtoshowtheadditionalmarginoffloodingtothe plantfloor.

ThedoorD20thresholdelevationwassurveyedtobe710.39feet(MSL),andthedoorD164threshold elevationwassurveyedtobe710.40feet(MSL).ThethresholdelevationofdoorD20is0.09feetbelowthe currentcalculatedfloodelevationforZoneIatD20of710.48feetMSL,andthethresholdelevationof doorD164is0.08feetbelowthecurrentcalculatedfloodelevationforZoneIatD164of710.48feetMSL.

DuringaPMPfloodevent,watercouldbepostulatedtoenterthebuildingsthroughdoorD20ordoorD 164.ThisconditionwasenteredintothesitesCAPthroughIR1413252.Theexistinganalysisusesahand calculation.ApreliminaryanalysiswasperformedbySiteEngineeringusingHECRAS(thesamehydraulic modelingprogramusedtoanalyzeZoneII),whichshowsthereissufficientmargintoplantfloodingdueto PMP.ThecorrectiveactionistoformalizethepreliminaryhydraulicanalysisonZoneIusingHECRASby issuingarevisiontothecalculation.

ThedoorD508thresholdelevationwassurveyedtobe710.29feetMSL.ThethresholdelevationofdoorD 508is0.19feetbelowtheZoneIcalculatedfloodelevationof710.48feetMSL.APMPfloodeventcouldbe postulatedtoenterthebuildingsthroughD508.ThisconditionwasenteredintothesitesCAPthroughIR 1415966. The existing analysis uses a hand calculation. A preliminary analysis was performed by Site EngineeringusingHECRAS(thesamehydraulicmodelingprogramusedtoanalyzeZoneII),whichshows

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thereissufficientmargintoplantfloodingduetoPMP.Thecorrectiveactionistoformalizethepreliminary hydraulicanalysisonZoneIusingHECRASbyissuingarevisiontothecalculation.

OtherItemsAwaitingFinalDispositioninCAP During the review of CLB documents, a discrepancy was identified between the PMF flood elevation reported in the UFSAR and the hydraulic calculations (Calculations S66 and L002536). The highest calculatedfloodelevationforZoneI(northareaoftheplant)is710.48feetMSLbasedonCalculationS66.

ThehighestcalculatedfloodelevationforZoneII(southareaoftheplant)is710.37feetMSLbasedon CalculationL002536.However,theUFSARstatesthatthemaximumwatersurfaceelevationduetolocal intensePMPwouldnotexceed710.41feetMSL.ItappearsthattheUFSARwasnotupdatedthelasttime S66wasrevised.ThisdiscrepancywasdocumentedinIR1413252,andisbeingtrackedintheCAP.

RestrictedAccessAreas Four(4)penetrationsintheUnit1TurbineBuilding,three(3)penetrationsintheUnit2TurbineBuilding, eight(8)penetrationsintheOffGasFilterBuilding,andportionsofbasementfloorslabsandexteriorwalls intheTurbine,HeaterBay,AuxiliaryandOffGasFilterbuildingsthatarewithinscopewerenotwalked downduetohighradiationdoserates,andthereforewereconsideredrestrictedaccess.Theseareaswill bewalkeddownduringthenextrefuelingoutage.ThenextUnit2refuelingoutage(L2R14)iscurrently scheduledforFebruary11,2013toMarch6,2013,andthenextUnit1refuelingoutage(L1R15)iscurrently scheduledforFebruary10,2014toMarch1,2014.Inaddition,Units1and2ReactorBuildingtendon tunnelswereconsideredrestrictedareasbecausefloorplugshavetobepulledandradiationprotection supportforconfinedspaceisrequired.Accesstothetendontunnelsrequiresdisassemblyoffloorplugsto gain access, so it will be performed during the planned access currently scheduled to be completed by August26,2013.ThefeaturesconsideredtobeinrestrictedaccessareasareprovidedinTable5inSection 5.

InaccessibleAreas PortionsofbasementfloorslabsandexteriorwallsintheUnits1and2TurbineBuildingwereconsidered inaccessible because these areas cannot reasonably be inspected due to a significant personnel safety hazard.AcompletelistofslabandwalllocationsisprovidedinTable6ofSection5.Thesefeaturesarein high radiation rooms that remain high radiation rooms during outages, and therefore are considered inaccessible. The inaccessible rooms contain tanks that hold highlyradioactive fluids and sludge. An additionalareathatisconsideredinaccessibleistheFC(FuelPoolCooling)filterrooms,duetoveryhigh radiationlevels.Assuminga10minuteinspectionperroom,itwasestimatedbyRadiationProtectionthat thetotaldosereceivedbytheinspectionteam(onlyusingtwopeople)wouldbe2.494REM.Thisdoesnot includetheextradosethatwouldbereceivedwhileinspectingtheFCfilterrooms,orextradosereceived from support activities for entering the tank rooms and FC filter rooms, including floor cleaning/decontamination.Thereisnoplannedorforeseentimewhentheseroomswouldbecomenon highradiationrooms.Therefore,becausetheroomsarehighradiationareas,theestimateddosetothe team is very high, and the rooms are not planned to become nonhigh radiation areas, the rooms are consideredinaccessible.ThisalsoappliestotheFCfilterrooms.Sincetheseareaswerenotabletobe walkeddown,alternatemethodswereusedtoevaluatethem,whicharedescribedbelow.

Basementfloorslabsandexteriorwallsimmediatelyadjacenttotheinaccessibleareaswerewalkeddown anddeterminedacceptable.Theslabsintheseroomsandthesurroundingslabsthatwereinspectedare part of the common basemat for the building complex, which is a minimum of 68 thick concrete,

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includingthemudmatbelowandthefinishfloorabove.Additionally,thereisundisturbedlowpermeability claybeneaththemudmat,sothereisreasonableassurancethatthefloorsintheseroomsarecapableof performingtheirdesignfunctionduringadesignbasisfloodingevent.TheexteriorwallsoftheFCfilter rooms(therearenoexteriorwallsforthetankrooms),whichincludesthewallsfromelevation677.00feet MSLtoelevation710.50MSLfeet,are4feetthick.Nootherwallsintheentirecomplexweredeclared Deficiencies.GiventhethicknessofthewallandbecausenootherwallsweredeclaredDeficient,itwas judgedthatthissectionofwallisacceptableandwouldbeabletoperformitsdesignfunctionintheevent ofadesignbasisflood.Thefeaturesconsideredtobeininaccessibleareasduetohighradiationdoserates thatwillnotdecreaseduringoutagearelistedinTable6inSection5.

Observationsonpenetrationsinbasementfloorslabsinaccessibleareasweremadeduringthefloorslab walkdowns.Onlytwolocationsofthefloorslabwerenotimmediatelyjudgedasacceptableduringthe walkdownduetoobservedcrackingintheslabandminorapparentgroundwaterinleakage.Neitherofthe inleakage locations was due to degraded conditions of or around penetrations. Based on those observations,thereisreasonableassurancethatfloorslabpenetrationsininaccessibleareasarecapableof performingtheirfloodprotectionfunction.

Sump pits were considered inaccessible due to significant disassembly of equipment to gain access.

However, no signs of potential groundwater inleakage were observed around sump pits during the basement floor slab walkdowns. In addition, the following items provide reasonable assurance that groundwaterorfloodwaterwillnotchallengesafetyrelatedplantequipment:

IntheReactorBuilding,concreteslabsaregenerallyaminimumof5feetthickaroundthesumps.

IntheDieselBasementandTurbineBuilding,concreteslabsaregenerallyaminimumof3feetthick aroundthesumps.Thisiscomparabletoslabsthatwereinspectedandfoundtonotbedeficient.

LaSalle has a nearly impervious clay layer (undisturbed) surrounding the sumps, which would minimizeflowintheeventacrackintheslabispresent.

Sumppumpsarelocatedthroughoutthebuildings,whichcouldpotentiallyaccommodateanysmall amount of leakage if it were to penetrate through any potential cracks in the sump pits. Sump pumpsgenerallyhavebackupsandhilevelalarms.

PreventativeMaintenanceisperformedonmultiplesumppumpsinallbuildings.

TheTurbineBuilding(whereamajorityofsumpsarelocated)isdesignedtoretainasubstantial amountofwaterbeforeallowingwatertoentertheAuxiliary,Diesel,orReactorBuildings.

Failureofthesefeaturestoperformtheirfloodprotectionfunctionwouldmeanthatwaterwouldenterthe plantthroughacrackintheslab,sumppitorwall.Iffailureofthesefeaturesweretooccur,thefailures wouldbeindependentofeachotherduetothefeaturelocationsandthenatureofthefailure.Depending on the location of multiple failures occurring, the inleakage could potentially cause greater water accumulationthanifonlyonefailureoccurred.However,itisreasonabletoconcludethattheamountof waterseepingthroughthecrackwouldberelativelysmallconsideringthenearlyimpermeableclaybelow theslabandmudmat,andsurroundingtheopengradedstoneoutsideofthewalls.Also,therearemultiple sump pumps in all buildings that could remove any of this seepage, many of which have preventive maintenanceperformedonthem.Watertightdoorsseparateroomsthatcontainredundantsafetyrelated equipmentintheDieselGeneratorBuildingandReactorBuilding.Additionally,thesafetyrelatedbuildings areprotectedtoanelevationof6734fromtheTurbineBuilding,sowaterwouldfirsthavetofillthe entireTurbineBuildingBasement(whichisatelevation663)morethan10feetdeepbeforesafetyrelated

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equipmentwouldbeaffected,ifthesumppumpsintheTurbineBuildingweretofail.Thisisasignificant volumethatisnotpostulatedtobereachedduringashorttermPMPeventwithwaterenteringtheplant viapostulatedcracks.

UnanalyzedConditions Therewerenotanyunanalyzedconditionsidentifiedduringthefloodingwalkdowns.

g. RequestedInformationItem2(g)-Cliff-EdgeEffectsandAvailablePhysicalMargin 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.

APMinformationwascollectedduringthewalkdownsinaccordancewithguidanceprovidedinNEI1207 andthefinalresolutiontoFAQ006.APMwascollectedtoprimarilysupporttheresponsetoEnclosure2of 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 systemstomitigatetherisk.

SincethewalkdownswerecompletedpriortothefinalresolutionofFAQ006(September13,2012),APM informationwascollectedanddocumentedontheWalkdownRecordFormusingtheoldapproach;that is,whereapplicable,asimplemeasurementofthedifferencebetweenthelicensingbasisfloodheightand thefloodheightatwhichwatercouldaffectanSSCimportanttosafety.

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.

Thesitehasrequestedapreventativemaintenanceplantoperiodicallyinspectandmaintainroofdrainsto assuretheyremainopenandfunctionalduringrainevents.ServiceRequest00079453wascreated.

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5. CONCLUSIONS TheFloodingWalkdownatLaSalleCountyStationwasconductedbetweenAugust10andSeptember14, 2012andincludedavisualinspectionofbelowgradewalls,penetrations,basementfloorslabs,roofsand thesitedrainageplan;also,availablephysicalmarginsurveysofabovegradeexteriordoors,removable wallpanelsandtheradioactivewasteloadingdockswereperformed.Alistoffloodprotectionfeatures consideredtobeacceptableandcapableofperformingtheirfloodprotectionfunctionisprovidedinTable 2.

Thirty(30)floodprotectionfeatureswereobservedtobeinaconditionthatcouldnotbeimmediately judgedasacceptableduringthewalkdownbutwerenotconsidereddeficienciesaftertheobservationwas reviewedintheCAP.AsummaryofthosefeaturesisprovidedinTable3.

Five(5)floodprotectionfeatureswereobservedtobeinaconditionthatcouldnotbeimmediatelyjudged asacceptableduringthewalkdownandwereconsidereddeficienciesaftertheobservationwasreviewedin theCAP.Notethatthree(3)ofthesedeficiencieswereforfeaturesnotonthewalkdownlist,becausethey wereoriginallysurveyedforAvailablePhysicalMargin(APM)only.Asummaryofthosefeaturesisprovided inTable4.

Thirtythree(33)featureswereinareasconsideredtoberestrictedaccessandaredeferredtooutagedue tohighradiationdoseratesorsignificantequipmentdisassembly.Theseareaswillbewalkeddownduring outage.ThefeaturesconsideredtobeinrestrictedareasarelistedinTable5.

Seven (7) features were considered inaccessible because they are in rooms that cannot reasonably be inspectedduetosignificantpersonnelsafetyhazard.Theseinaccessibleroomshavehighdoseratesthat donotdecreaseduringoutages.One(1)feature,sumppits,wasconsideredinaccessiblebecauseitwould takesignificantequipmentdisassemblytoinspect.Thefeaturesconsideredtobeininaccessibleareasare listedinTable6.

Thesitehasrequestedapreventativemaintenanceplantoperiodicallyinspectandmaintainroofdrainsto assuretheyremainopenandfunctionalduringrainevents.ServiceRequest00079453wascreated.

Table#1:Summary-FeaturesIncludedintheWalkdownScope

FeatureType Total Number Passive-Incorporated 185 Passive-Temporary 0

Active-Incorporated 0

Active-Temporary 0

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Table#2:InspectedFloodingFeaturesMeetingAcceptanceCriteria FeaturesImmediatelyJudgedasAcceptable FeatureID#

Description Passive/ActiveIncorporated/Temporary 1

1AB70 Penetration Passive-Incorporated 2

1DR19 Penetration Passive-Incorporated 3

1DR22 Penetration Passive-Incorporated 4

1DR29 Penetration Passive-Incorporated 5

1DR30 Penetration Passive-Incorporated 6

1DR35 Penetration Passive-Incorporated 7

1DR36 Penetration Passive-Incorporated 8

1DR37 Penetration Passive-Incorporated 9

1DR38 Penetration Passive-Incorporated 10 1DR39 Penetration Passive-Incorporated 11 1DR40 Penetration Passive-Incorporated 12 1DR6 Penetration Passive-Incorporated 13 1RB256 Penetration Passive-Incorporated 14 1RB258 Penetration Passive-Incorporated 15 1RB33 Penetration Passive-Incorporated 16 1RB50 Penetration Passive-Incorporated 17 1RB503 Penetration Passive-Incorporated 18 1RB504 Penetration Passive-Incorporated 19 1RB51 Penetration Passive-Incorporated 20 1RB61 Penetration Passive-Incorporated 21 1RB64 Penetration Passive-Incorporated 22 1RB67 Penetration Passive-Incorporated 23 1RB7 Penetration Passive-Incorporated 24 1RB83 Penetration Passive-Incorporated 25 1RB84 Penetration Passive-Incorporated 26 1TB525 Penetration Passive-Incorporated 27 1TB1108 Penetration Passive-Incorporated 28 1TB1272 Penetration Passive-Incorporated 29 1TB1273 Penetration Passive-Incorporated 30 1TB1310 Penetration Passive-Incorporated

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Table#2:InspectedFloodingFeaturesMeetingAcceptanceCriteria FeaturesImmediatelyJudgedasAcceptable FeatureID#

Description Passive/ActiveIncorporated/Temporary 31 1TB264 Penetration Passive-Incorporated 32 1TB266 Penetration Passive-Incorporated 33 1TB267 Penetration Passive-Incorporated 34 1TB270 Penetration Passive-Incorporated 35 1TB274 Penetration Passive-Incorporated 36 1TB275 Penetration Passive-Incorporated 37 1TB517 Penetration Passive-Incorporated 38 1TB58 Penetration Passive-Incorporated 39 1TB591 Penetration Passive-Incorporated 40 1TB592 Penetration Passive-Incorporated 41 1TB593 Penetration Passive-Incorporated 42 1TB595 Penetration Passive-Incorporated 43 1TB673 Penetration Passive-Incorporated 44 1TB721 Penetration Passive-Incorporated 45 1TB75 Penetration Passive-Incorporated 46 1TB94 Penetration Passive-Incorporated 47 1WS03D20inPipe Penetration Passive-Incorporated 48 2DR1 Penetration Passive-Incorporated 49 2DR10 Penetration Passive-Incorporated 50 2DR13 Penetration Passive-Incorporated 51 2DR2 Penetration Passive-Incorporated 52 2DR3 Penetration Passive-Incorporated 53 2DR4 Penetration Passive-Incorporated 54 2DR6 Penetration Passive-Incorporated 55 2DR7 Penetration Passive-Incorporated 56 2DR8 Penetration Passive-Incorporated 57 2RB1 Penetration Passive-Incorporated 58 2RB120 Penetration Passive-Incorporated 59 2RB147 Penetration Passive-Incorporated 60 2RB163 Penetration Passive-Incorporated

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Table#2:InspectedFloodingFeaturesMeetingAcceptanceCriteria FeaturesImmediatelyJudgedasAcceptable FeatureID#

Description Passive/ActiveIncorporated/Temporary 61 2RB2 Penetration Passive-Incorporated 62 2RB26 Penetration Passive-Incorporated 63 2RB27 Penetration Passive-Incorporated 64 2RB3 Penetration Passive-Incorporated 65 2RB6 Penetration Passive-Incorporated 66 2RB70 Penetration Passive-Incorporated 67 2RB74 Penetration Passive-Incorporated 68 2RB75 Penetration Passive-Incorporated 69 2RB76 Penetration Passive-Incorporated 70 2WS03D20inPipe Penetration Passive-Incorporated 71 4"pipe Penetration Passive-Incorporated 72 ElectricalConduitGroup 4

Penetration Passive-Incorporated 73 Four(4)PipesEncasedin Concrete Penetration Passive-Incorporated 74 GENERICCASTIRON Penetration Passive-Incorporated 75 LakeScreenHouseWalls ConcreteWall Passive-Incorporated 76 OB170 Penetration Passive-Incorporated 77 OB171 Penetration Passive-Incorporated 78 OB173 Penetration Passive-Incorporated 79 OB66 Penetration Passive-Incorporated 80 OB67 Penetration Passive-Incorporated 81 OB69 Penetration Passive-Incorporated 82 OB70 Penetration Passive-Incorporated 83 OB75 Penetration Passive-Incorporated 84 OB76 Penetration Passive-Incorporated 85 OB77 Penetration Passive-Incorporated 86 OB78 Penetration Passive-Incorporated 87 OB79 Penetration Passive-Incorporated 88 OB80 Penetration Passive-Incorporated

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Table#2:InspectedFloodingFeaturesMeetingAcceptanceCriteria FeaturesImmediatelyJudgedasAcceptable FeatureID#

Description Passive/ActiveIncorporated/Temporary 89 OffGas Filter Building BasementFloorSlab Slab Passive-Incorporated 90 OffGas Filter Building ExteriorWall(Basement)

ConcreteWall Passive-Incorporated 91 OffGas Filter Building Exterior Wall (Upper Basement)

ConcreteWall Passive-Incorporated 92 Pipeencasedinconcrete Penetration Passive-Incorporated 93 ReactorBuildingRoof Roof Passive-Incorporated 94 Sch.40 Penetration Passive-Incorporated 95 U2DGBuildingRoof Roof Passive-Incorporated 96 Unit 1 Diesel Generator BuildingBasementFloor Slab Slab Passive-Incorporated 97 Unit 1 Diesel Generator Building Exterior Wall (UpperBasement)

ConcreteWall Passive-Incorporated 98 Unit 1 Reactor Building BasementFloorSlab Slab Passive-Incorporated 99 Unit 1 Reactor Building ExteriorWall(Basement)

ConcreteWall Passive-Incorporated 100 Unit 1 Reactor Building Exterior Wall (Upper Basement)

ConcreteWall Passive-Incorporated 101 Unit 1 Turbine Building ExteriorWall(Basement)

ConcreteWall Passive-Incorporated 102 Unit 1 Turbine Building Exterior Wall (Upper Basement)

ConcreteWall Passive-Incorporated 103 Unit 2 Diesel Generator Building Exterior Wall (UpperBasement)

ConcreteWall Passive-Incorporated 104 Unit 2 Reactor Building BasementFloorSlab Slab Passive-Incorporated 105 Unit 2 Reactor Building ExteriorWall(Basement)

ConcreteWall Passive-Incorporated

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Table#2:InspectedFloodingFeaturesMeetingAcceptanceCriteria FeaturesImmediatelyJudgedasAcceptable FeatureID#

Description Passive/ActiveIncorporated/Temporary 106 Unit 2 Reactor Building Exterior Wall (Upper Basement)

ConcreteWall Passive-Incorporated 107 Unit 2 Turbine Building BasementFloorSlab Slab Passive-Incorporated 108 Unit 2 Turbine Building Exterior Wall (Upper Basement)

ConcreteWall Passive-Incorporated 109 10inchSleeve Penetration Passive-Incorporated 110 1AB69 Penetration Passive-Incorporated 111 GenericCastIron3 Penetration Passive-Incorporated 112 SiteDrainagePlan-PlantConfiguration SiteDrainage Passive-Incorporated

Table#3:InspectedFeaturesNotImmediatelyJudgedasAcceptable FloodFeaturesNotMeetingAcceptanceCriteria,NotDesignatedasDeficientThroughCAP FeatureID#

Description Observation Component Operability Resolution 1

1DR20 Penetration Corrosionon bottomof penetrationsleeve.

Yes, documented inIR1399525 RecommendedActions:

Cleansurfacecorrosion, paintandsealthe penetration.

2 1DR27 Penetration Corrosiononthe bottomofthepipe penetrationsleeve, andflamecutting ofsealplatenot associatedwith waterdegradation.

Yes, documented inIR1399598 Immediateactionstaken:

Confirmedtheabilityof thepenetrationsleeveto performitsdesign function.Recommended Actions:

InitiateaDocument ChangeRequestorother actionsasappropriate (forexample,weld overlay torestoretooriginal designcondition).

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Table#3:InspectedFeaturesNotImmediatelyJudgedasAcceptable FloodFeaturesNotMeetingAcceptanceCriteria,NotDesignatedasDeficientThroughCAP FeatureID#

Description Observation Component Operability Resolution 3

1DR28 Penetration Corrosion observedatthe bottomofthe sleeve.Signsof pastleakage(i.e.

waterstains)found belowthe penetration.

Yes, documented inIR1399536 RecommendedActions:

Cleansurfacecorrosion, paintandsealthe penetration.

4 1RB13 Penetration Surfacerustingon bottom

Yes, documented inIR1426637 RecommendedActions:

Cleansurfacecorrosion, paint/sealthe penetration/piping.

5 1TB1270 Penetration Rust,corrosionand stainingbelowthe feature.

Yes, documented inIR1401010 RecommendedActions:

Removerust,inspectpipe andpenetration.Sealthe penetration.

6 1TB1271 Penetration Rust/corrosionof sleeveandpipe.

Stainingfrom apparentwater leaksbelowthe feature.

Yes, documented inIR1401001 RecommendedActions:

Therubberpenetration sealmustberepairedor replaced.Whenrepairing orreplacingtheseal,the conditionoftheWD pipingshouldbe evaluatedforpotential replacementduetothe amountofcorrosionon thepiping.

Themissinginsulation shouldbereplaced.

7 1TB265 Penetration Stalactiteson bottomoffeature.

Signsofcorrosion.

Yes, documented inIR1400652 RecommendedActions:

Removerustandcalcified material,paintandreseal thepenetration.

8 1TB269 Penetration Rustandflakingon therightsideof thefeature.

Yes, documented inIR1400673 RecommendedActions:

Removerust,paintand reseal.

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Table#3:InspectedFeaturesNotImmediatelyJudgedasAcceptable FloodFeaturesNotMeetingAcceptanceCriteria,NotDesignatedasDeficientThroughCAP FeatureID#

Description Observation Component Operability Resolution 9

1TB96 Penetration Rustandflakeson bottomoffeature.

Featurematerialis degrading,staining belowpenetration.

Yes, documented inIR1426636 RecommendedActions:

Cleansurfacecorrosion, paint/sealthe penetration.

10 2DR9 Penetration Rustandsurface corrosionpresent onbottomof sleevewithslight flaking.Signsof slightapparent groundwaterin leakage.

Yes, documented inIR1400278 RecommendedActions:

Cleansurfacecorrosion, paintandsealthe penetration.

11 2TB1 Penetration Rustandflaking observedonthe pipeandsleeve.

Waterstainson wallbelow penetration

Yes, documented inIR1400662 RecommendedActions:

Removerust,paintand resealthepenetration.

12 30inchpipe Penetration Rustandflaking wereobserved, alongwithsignsof leakageonthewall belowthepipe.

Yes, documented inIR1400252 RecommendedActions:

Cleansurfacecorrosion, paintandsealthe penetration.

13 ElectricalConduit Group Penetration Evidenceofwater staining,butno signsofactive leakage.Small amountof corrosionpresent atbottomofthe penetrations,but doesnotaffect structuralintegrity.

Yes, documented inIR1412024 Conduitsarecontinuous toabove710'6"anddo nothaveapointwhere watercanenter.

14 ElectricalConduit Group2 Penetration Evidenceofwater staining,butno signsofactive leakage.Small amountof corrosionpresent atbottomofthe penetrations,but doesnotaffect structuralintegrity.

Yes, documented inIR1412028 Conduitsarecontinuous toabove710'6"anddo nothaveapointwhere watercanenter.

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Table#3:InspectedFeaturesNotImmediatelyJudgedasAcceptable FloodFeaturesNotMeetingAcceptanceCriteria,NotDesignatedasDeficientThroughCAP FeatureID#

Description Observation Component Operability Resolution 15 GenericCastIron4 Penetration Corrosionon bottomofpipe.

Signsofleakage.

Yes, documented inIR1400635 RecommendedActions:

Removerust,paintand resealthepenetration.

16 Unit1Auxiliary BuildingExteriorWall (Basement)

Wall Leachingatvarious locationsfrom J:9_15.Water stainsonwalland flooratJ:11_12.

Yes, documented inIR1401610 RecommendedActions:

Engineeringtomonitor wallforemergentground waterinleakage (seepage) pertheStructural MonitoringProgramand initiateanappropriateIR asrequiredifleakageis observed.

17 Unit1Diesel GeneratorBuilding ExteriorWall (Basement)

Wall Rustcolored calciumleaching showingfrom3 footlongcrackin DIVICSCS.

Yes, documented inIR1400272 Immediateactionstaken:

Evaluatedthecondition perAmericanConcrete InstituteACI349.3R02 (Reapproved2010),

"EvaluationofExisting NuclearSafetyRelated ConcreteStructures",

Chapter5"Evaluation Criteria".Recommended Actions:

Continuemonitoringfor spallingoftheconcreteat thislocationinthe StructuresMonitoring Program.

18 Unit1IceMelt PenetrationA Penetration Entirepitareais consideredpartof thispenetration(ie wallsandslab).

Conditionnot acceptabledueto leaching;evidence ofwater leakage/accumulat ion.

Yes, documented inIR1401110 RecommendedActions:

Cleanthecalciumbuildup ontheU1DeicingPit"A" and"B"penetrations andsealthepenetrations asnecessary.

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Table#3:InspectedFeaturesNotImmediatelyJudgedasAcceptable FloodFeaturesNotMeetingAcceptanceCriteria,NotDesignatedasDeficientThroughCAP FeatureID#

Description Observation Component Operability Resolution 19 Unit1IceMelt PenetrationB Penetration Entirepitareais consideredpartof thispenetration(ie wallsandslab).

Conditionnot acceptabledueto leaching;evidence ofwater leakage/accumulat ion.

Yes, documented inIR1401110 RecommendedActions:

Cleanthecalciumbuildup ontheU1DeicingPit"A" and"B"penetrations andsealthepenetrations asnecessary.

20 Unit1TurbineBuilding BasementFloorSlab Slab Crackbetween concretefloorslab andconcrete containmentcurb inMudsRoom.

Waterstainsand debrisobserved aroundthecrack.

Yes, documented inIR1400720 andIR 1401884 Immediateactionstaken:

NotifiedtheWork ExecutionCenterofthe wateronthefloor (possiblefallhazard).The areawillberopedoffand posted.

RecommendedActions:

(MUDSRoom):Clean floorandsealtheleaksin thefloor.(DHTRDRN PMPRoom):Engineering tomonitorthefloorfor emergentgroundwater inleakage(seepage)per theStructuralMonitoring Programandinitiatean appropriateIRas requiredifleakageis observed.

21 Unit2Auxiliary BuildingExteriorWall (Basement)

Wall Leachingand calcificationon wallsinplaceson Jlinefrom15to 21.

Yes, documented inIR1401610 RecommendedActions:

Engineeringtomonitor wallforemergentground waterinleakage (seepage) pertheStructural MonitoringProgramand initiateanappropriateIR asrequiredifleakageis observed.

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Table#3:InspectedFeaturesNotImmediatelyJudgedasAcceptable FloodFeaturesNotMeetingAcceptanceCriteria,NotDesignatedasDeficientThroughCAP FeatureID#

Description Observation Component Operability Resolution 22 ElectricalConduit Group3 Penetration Slightwater stainingof thewallbelow theconduitsdue topastleakage.

Yes, documented inIR1412039 Theconduitshadrecently beensealedtostopthe inleakage.No recommendedor immediateaction.

23 U1DGBuildingRoof Roof Cloggedroof drains

Yes, documented inIR1402098 RecommendedActions:

Cleantheroofdrains.

24 1inchconduit Penetration Conduitisnot documentedin plantdrawings

Yes, documented inIR1419529 ImmediateActions:

Searcheddrawingsto findtheconduit-nothingwasfound.

Usedaborescopeto identifyaseal.

RecommendedActions:

Asanenhancementto thecurrentseal,awork requestwasinitiatedto putductsealintothe conduit.

25 Auxiliary&Turbine BuildingRoof Roof Openbathroom ventscould potentially provideflowpath forwater

Yes, documented inIR1424707 ImmediateAction:

Performedpreliminary evaluation,which showedthatwater wouldnotenterthe ventsinthecaseofa designbasisrainevent.

RecommendedAction:

Formalizethe evaluation.

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Table#3:InspectedFeaturesNotImmediatelyJudgedasAcceptable FloodFeaturesNotMeetingAcceptanceCriteria,NotDesignatedasDeficientThroughCAP FeatureID#

Description Observation Component Operability Resolution 26 Unit2Diesel GeneratorBuilding BasementFloorSlab Slab Possible groundwater infiltratingfrom crackinslabinthe Division1CSCS room.

Yes, documented inIR1400268 RecommendedActions:

Groutfloortostop groundwaterinleakage.

Replacestanchion baseplate associatedwithFullFlow Testinstrumentation 2FE038andadd1.5 inches ofgrout.Clean/paintthe stanchionbaseplate associatedwith instrument 2FIFC035.

27 Unit2Diesel GeneratorBuilding ExteriorWall (Basement)

Wall Leaking,leaching andcalcification observedonwalls inDIVIIIDGSTand DIVICSCS.

Yes, documented inIR1400223 RecommendedActions:

Cleanandgroutany visibleopenings.

28 Unit2IceMelt PenetrationA Penetration Entirepitareais consideredpartof thispenetration(ie wallsandslab).

Conditionnot acceptabledueto leaching;evidence ofwater leakage/accumulat ion.

Yes, documented inIR1401119 RecommendedActions:

Cleanthecalciumbuildup ontheU2DeicingPit"A" and"B"penetrations andsealthepenetrations asnecessary.

29 Unit2IceMelt PenetrationB Penetration Entirepitareais consideredpartof thispenetration(ie wallsandslab).

Conditionnot acceptabledueto leaching;evidence ofwater leakage/accumulat ion.

Yes, documented inIR1401119 RecommendedActions:

Cleanthecalciumbuildup ontheU2DeicingPit"A" and"B"penetrations andsealthepenetrations asnecessary.

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Table#3:InspectedFeaturesNotImmediatelyJudgedasAcceptable FloodFeaturesNotMeetingAcceptanceCriteria,NotDesignatedasDeficientThroughCAP FeatureID#

Description Observation Component Operability Resolution 30 Unit2TurbineBuilding ExteriorWall (Basement)

Wall Crackinwallin AmertapRoom.

Leachingand waterstainsonthe wallandfloor belowthecrack.

Also, calcificationand stainingon21line fromLtoR.

Yes, documented inIR1401906

&IR1402075 RecommendedActions (Amertap):

Engineeringtomonitor thenorthAmertapRoom Wallforemergentground waterinleakage (seepage)perthe StructuralMonitoring Programandinitiatean appropriateIRas requiredifleakageis observed.

RecommendedActions (21linefromLtoR):

Engineeringtomonitor the2WF03TA/BRoom NorthWallforemergent ground waterinleakage (seepage)perthe StructuralMonitoring Programand initiateanappropriateIR asrequiredifleakageis observed.

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Table#4:InspectedFeaturesNotImmediatelyJudgedasAcceptable FloodFeaturesNotMeetingAcceptanceCriteria,DesignatedasDeficientthroughCAP FeatureID#

Description Observation Component Deficiency Resolution 1

1TB1144 Penetration Significantrustand corrosion,plateis separatedfrom sleeve.

Yes, documented inIR1401068 ImmediateActions:It wasdeterminedsafety relatedequipmentwould notbejeopardizedinthe eventofadesignbasis floodevent.

RecommendedActions:

Thesealmustberepaired andtheassociatedpiping inspectedandrepairedas required.

2 GenericCastIron2 Penetration Nosealbetween pipeandsleeve.

Pipeandsleeve materialshows heavyrustand apparent deterioration.

Stainingbelow penetrationshows signsofpossible groundwater intrusion.

Yes, documented inIR1401463 ImmediateActions:It wasdeterminedsafety relatedequipmentwould notbejeopardizedinthe eventofadesignbasis floodevent.

RecommendedActions:

Thepenetrationseal mustbereplaced.

3 DoorD20andDoorD 164 Exterior Door Threshold Thethreshold elevationswere belowthe calculatedflood elevation

Yes, documented inIR1413252 ImmediateActions:

Performedapreliminary analysis,whichshows thereissufficientmargin toplantfloodingdueto PMP.

RecommendedActions:

Formalizetheanalysis byrevisingthe applicable calculation(s),whichis beingtrackedthrough CAP.

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Table#4:InspectedFeaturesNotImmediatelyJudgedasAcceptable FloodFeaturesNotMeetingAcceptanceCriteria,DesignatedasDeficientthroughCAP FeatureID#

Description Observation Component Deficiency Resolution 4

DoorD479 Exterior Door Threshold Thethreshold elevationwas belowtheCLB floodelevation

Yes, documented inIR1416084 ImmediateAction:

Verifiedtheexisting floodbarrierwas intact.

RecommendedAction:

Revisetheanalysisto showtheadditional marginoffloodingto theplantfloor.Thisis beingtrackedthrough CAP.

5 DoorD508 Exterior Door Threshold Thethreshold elevationwas belowtheCLB floodelevation

Yes, documented inIR1415966 ImmediateActions:

Performeda preliminaryanalysis, whichshowsthereis sufficientmarginto plantfloodingdueto PMP.

Recommended Actions:Formalizethe analysisbyrevisingthe applicable calculation(s),whichis beingtrackedthrough CAP.

Table#5:FeaturesClassifiedasRestrictedAccess FeatureID#

Description Reason Resolution 1

OffGasPipe1 Penetration Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 2

OffGasPipe2 Penetration Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 3

OffGasPipe3 Penetration Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14

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Table#5:FeaturesClassifiedasRestrictedAccess FeatureID#

Description Reason Resolution 4

OffGasPipe4 Penetration Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 5

OffGasFilterBuilding BasementFloorSlab_1 rowAA.5toAD andcolumn11 to12.5 Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 6

OffGasFilterBuilding BasementFloorSlab_2 rowAA.5toAD andcolumn12.5 to14 Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 7

OffGasFilterBuilding BasementWall2_1 rowAA.5toAD andcolumn11 to12.5 Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 8

OffGasFilterBuilding BasementWall2_2 rowAA.5toAD andcolumn12.5 to14 Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 9

OffGasFilterBuilding UpperBasementWall 2_1 11linefromAB toADandAD linefrom11to 12.5 Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 10 OffGasFilterBuilding UpperBasementWall 2_2 ADlinefrom 12.5to14and 14linefromAB toAD Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 11 Unit1AuxiliaryBuilding UpperBasementWall-SteamTunnel 8.9linefromN toS(El.687)

Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 12 Unit1HeaterBay UpperBasement ExteriorWall(HDT Room)

Ylinefrom7to 11 Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 13 Unit1TurbineBuilding BasementFloorSlab2-CondenserPit column5to11 andStoV Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 14 Unit1TurbineBuilding BasementWall2-CondenserPit column5to11 andStoV Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14

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Table#5:FeaturesClassifiedasRestrictedAccess FeatureID#

Description Reason Resolution 15 Unit1TurbineBuilding UpperBasementWall2 (UpperCondenserPit) andHPHeaterroom 5linefromS.5 toU.5andSline from5to8.9 and8linefrom RtoS(El.

704.5)

Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 16 Unit2AuxiliaryBuilding UpperBasementWall-SteamTunnel 21.1linefrom RtoS(El.687)

Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 17 Unit2HeaterBay UpperBasement ExteriorWall(HDT Room)

Ylinefrom19 to23and23 linefromX.5to Y

Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 18 Unit2TurbineBuilding BasementFloorSlab2-CondenserPit column19to 24andStoV.

Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 19 Unit2TurbineBuilding BasementWall2-CondenserPit column19to 24andStoV.

Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 20 Unit2TurbineBuilding UpperBasementWall2 (UpperCondenserPit) andHPHeaterroom Vlinefrom23to 25,25linefrom S.5toU.5,andS linefrom21to 25and22line fromRtoS(El.

704.5)

Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 21 1TB271 Penetration Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 22 1TB516 Penetration Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 23 2TB114 Penetration Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 24 OB156 Penetration Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14

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Table#5:FeaturesClassifiedasRestrictedAccess FeatureID#

Description Reason Resolution 25 OB168 Penetration Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 26 OB169 Penetration Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 27 OB71 Penetration Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 28 OB72 Penetration Highradiationdoseratesthat decreaseduringoutage Unit2refuelingoutage (L2R14)scheduledfor 2/11/133/6/13 29 OB73

Penetration Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 30 OB74 Penetration Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 31 OB81 Penetration Highradiationdoseratesthat decreaseduringoutage Unit1refuelingoutage (L1R15)scheduledfor 2/10/143/1/14 32 Unit1ReactorBuilding TendonTunnelFloor Slab EntireTendon TunnelSlab Disassemblyandradiation supportforconfinedspace Floorplugdisassembly andtendontunnel accessscheduled completeby8/26/13 33 Unit2ReactorBuilding TendonTunnelFloor Slab EntireTendon TunnelSlab Disassemblyandradiation supportforconfinedspace Floorplugdisassembly andtendontunnel accessscheduled completeby8/26/13

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Table#6:FeaturesClassifiedasInaccessible FeatureID#

Description Reason Resolution 1

Unit1Turbine Building BasementFloor Slab3 Basementtankroom floorslabswithinthis perimeter:13.4line fromXtoY,Ylinefrom 13.4to15,15linefrom W.6toY,W.6linefrom 14to15,14linefrom W.6toX,Xlinefrom 13.4to14, Featureisinhighradiation roomsthatremainhigh radiationroomsduring outages Reasonableassurance basedonsimilarfeatures analysis 2

Unit1Turbine Building BasementFloor Slab4 Basementtankroom floorslabsfrom column13to15and rowLtoV Featureisinhighradiation roomsthatremainhigh radiationroomsduring outages Reasonableassurance basedonsimilarfeatures analysis 3

Unit1Turbine Building BasementWalls3 FCfilterwallsfrom column13to15and rowYtoYa,Elevation 677to710.5 Featureisinhighradiation roomsthatremainhigh radiationroomsduring outages Reasonableassurance basedonsimilarfeatures analysis 4

Unit2Turbine Building BasementFloor Slab3 Basementtankroom floorslabswithinthis perimeter:15linefrom W.6toY,Ylinefrom 15to16,16linefromX toY,Xlinefrom16to 17.5,17.5linefrom W.6toX,W.6line from17.5to18,18line fromW.6toW,Wline from16to18,16line fromWtoW.6,W.6 linefrom15to16 Featureisinhighradiation roomsthatremainhigh radiationroomsduring outages Reasonableassurance basedonsimilarfeatures analysis 5

Unit2Turbine Building BasementFloor Slab4 Basementtankroom floorslabsfrom column15to17and rowLtoV Featureisinhighradiation roomsthatremainhigh radiationroomsduring outages Reasonableassurance basedonsimilarfeatures analysis 6

Unit2Turbine Building BasementFloor Slab5 Basementtankroom floorslabsfrom column18to19and rowLtoR Featureisinhighradiation roomsthatremainhigh radiationroomsduring outages Reasonableassurance basedonsimilarfeatures analysis

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Table#6:FeaturesClassifiedasInaccessible FeatureID#

Description Reason Resolution 7

Unit2Turbine Building BasementWalls3 FCfilterwallsfrom column15to18and rowYtoYa,Elevation 677to710.5 Featureisinhighradiation roomsthatremainhigh radiationroomsduring outages Reasonableassurance basedonsimilarfeatures analysis 8

SumpPits SumppitsintheReactor, Auxiliary,Diesel Generator,andTurbine Buildings Featureisinaccessibledueto significantdisassemblyofsump pumpassemblies Reasonableassurance basedonbasementfloor slabwalkdown observations,floorslab designandsumppumps

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.

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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. LaSalleCountyStation,UpdatedFinalSafetyAnalysisReport(UFSAR),Rev.19.

14. LaSalleCountyStation,TopicalDesignBasisDocumentFloodProtection(DBDLSM11),Rev.B.

15. NUREG/CR4832,SAND920537,VOL.7,AnalysisoftheLaSalleUnit2NuclearPowerPlant:Risk MethodsIntegrationandEvaluationProgram(RMIEP),ExternalEventScopingQuantification,M.K.

RavindraandH.Bacon.

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)

1. Exelon Generation Company, LLC (EGC) will complete the inspection of the 17 LaSalle Unit 1 features classified as restricted access and deferred due to inaccessibility. These items are listed in Table 5 of Enclosure 1.

L1R15 Spring 2014 Yes No

2. Exelon Generation Company, LLC (EGC) will complete the inspection of the 14 LaSalle Unit 2 features classified as restricted access and deferred due to inaccessibility. These items are listed in Table 5 of Enclosure 1.

L2R14 Spring 2013 Yes No

3. Exelon Generation Company, LLC (EGC) will complete the inspection of the LaSalle Unit 1 and 2 Reactor Building Tendon Tunnel Floor Slabs. These features are classified as restricted access and deferred due to inaccessibility. These items are listed in Table 5 of Enclosure 1.

August 30, 2013 Yes No