ML24225A169

10 CFR 50.46 Annual Report

ML24225A169
Person / Time
Site:	Peach Bottom
Issue date:	08/12/2024
From:	Para W Constellation Energy Generation
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
Download: ML24225A169 (1)

Text

,.,..,, 200 Energy Way

r Constellation . Kennett Square, PA 19348 www.Constellation.com

10 CFR 50.46

August 12, 2024

U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 NRC Docket Nos. 50-277 and 50-278

Subject:

10 CFR 50.46 Annual Report

In accordance with 10 CFR 50.46, "Acceptance criteria for e mergency core cooling systems for light-water nuclear power reactors," Paragraph (a)(3)(ii), Constellation Energy Generation, LLC (CEG) is submitting this letter and its attachments to meet the annual reporting requirements of the Emergency Core Cooli ng System (ECCS) Evaluation Model changes and errors for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

There are no regulatory commitments in this letter. If you have any questions concerning this letter, please contact Mr. Steven Bowers at 267-533-5101.

Respectfully,

Wendi Para Sr. Manager - Licensing Constellation Energy Generation, LLC

Attachments: 1. GNF2 Peak Cladding Temperature Rack- Up Sheet for PBAPS Unit 2

2. GNF3 Peak Cladding Temperature Rack -Up Sheet for PBAPS Unit 2

3. GNF2 Peak Cladding Temperature Rack -Up Sheet for PBAPS Unit 3

4. GNF3 Peak Cladding Temperature Rack -Up Sheet for PBAPS Unit 3

5. Assessment Notes for PBAPS

cc: USNRC Administrator, Region I USNRC Senior Resident Inspector, PBAPS USNRC Project Manager, PBAPS W. DeHaas, Pennsylvania Bureau of Radiation Protection S. Seaman, State of Maryland ATTACHMENT 1

GNF2 Peak Cladding Temperature Rack- Up Sheet for PBAPS Unit 2 AnnualReportoftheEmergencyCoreCoolingSystem EvaluationModelChangesand Errors AssessmentsasofAugust 12,2024 Attachment1 GNF2PeakCladdingTemperatu re RackUp SheetforPBAPS Unit2 Page1of1

PLANTNAME: PeachBottomAtomicPowerStation,Unit2 ECCSEVALUATIONMODEL: SAFER/PRIME REPORTREVISIONDATE: 08/12/2024 EVALUATION MODELVENDOR: GNF/GEH CURRENTOPERATINGCYCLE: 25

ANALYSIS OFRECORDCALCULATIONS

1. ProjectTa s kRe po r t,ExelonGenerationCompanyLLC,Pe a c hBottomAto m i cPo we r Station,Units2&3MELLLA+Ta s kT0407:ECCSLO C APe r fo r m a n c e ,000001622354R0, Revi si o n0,(PLM000N0296Revi si o n0), December2013.

FuelsAnalyzedinCalculationsandinOperation: GNF2 LimitingFuelTy p e  : GNF2 LimitingSingleFailure: BatteryFailure LimitingBreakLocation: RecirculationDischargeLine LimitingBreakSize 0.05 ft2(SmallBreak)

ReferencePe a kCladdingTe m p e r a t u r e(PCT)fo rGNF2Fuel:1920°F

MARGINALLOCATION A. PRIORLO CAASSESSMENTS(Note1) 10 CFR50.46Repo rtdated August15,2014(Note1.1) GNF2:PCT =5°F 10 CFR50.46Repo rtdated August10,2016(Note1.2) GNF2:PCT =0°F 10 CFR50.46Repo rtdated August10,2017(Note1.3) GNF2:PCT =0°F 10 CFR50.46Repo rtdated August10,2018(Note1.4) GNF2:PCT =0°F 10 CFR50.46Repo rtdated August12,2019(Note1.5) GNF2:PCT =0°F 10 CFR50.46Repo rtdated August12,2020(Note1.6) GNF2:PCT =0°F 10 CFR50.46Repo rt(30Day Repo rt)datedNovember05, 2020 PCT =37°F (Note1.7) GNF2:

10 CFR50.46Repo rtdated August12,2021(Note1.8) GNF2:PCT =0°F 10 CFR50.46Repo rtdated August12,2022(Note1.9) GNF2:PCT =0°F 10 CFR50.46Repo rtdated August14,2023(Note1.10) GNF2:PCT =0°F NetPCT GNF2: 1962°F

B. CURRENTLO C AASSESSMENTS(Note2)

To t a lPCTChangefromCurrentAssessments(Note2) GNF2: PCT=0°F Cumulative PCTChangefromCurrentAssessments GNF2:lPCTl =0°F NetPCT GNF2: 1962°F ATTACHMENT 2

GNF3 Peak Cladding Temperature Rack- Up Sheet for PBAPS Unit 2 AnnualReportoftheEmergencyCoreCoolingSystem EvaluationModelChangesand Errors AssessmentsasofAugust 12,2024 Attachment2 GNF3PeakCladdingTemperatu re RackUp SheetforPBAPS Unit2 Page1of1

PLANTNAME: PeachBottomAtomicPowerStation,Unit2 ECCSEVALUATIONMODEL: SAFER/PRIME REPORTREVISIONDATE: 08/12/2024 EVALUATION MODELVENDOR: GNF/GEH CURRENTOPERATINGCYCLE: 25

ANALYSIS OFRECORDCALCULATIONS

1. Pea chBottomAto m i cPo werStationUnits2&3GNF3ECCSLO C A Eva l u a t i o n ,005N9630R0, Rev is io n0, April2021.

FuelsAnalyzedinCalculationsandinOperation: GNF3 LimitingFuelTy p e  : GNF3 LimitingSingleFailure: BatteryFailure LimitingBreakLocation: RecirculationDischargeLine LimitingBreakSize 0.05 ft2(SmallBreak)

ReferencePe a kCladdingTe m p e r a t u r e(PCT)fo rGNF3Fuel:2040°F

MARGINALLOCATION

A. PRIORLO CAASSESSMENTS(Note1)

10 CFR50.46Repo rtdated August14,2023(Note1.10) GNF3: PCT =0°F

NetPCT GNF3: 2040°F

B. CURRENTLO C AASSESSMENTS(Note2)

To t a lPCTChangefromCurrentAssessments(Note2) GNF3: PCT=0°F Cumulative PCTChangefromCurrentAssessments GNF3: lPCTl =0°F

NetPCT GNF3: 2040°F ATTACHMENT 3

GNF2 Peak Cladding Temperature Rack- Up Sheet for PBAPS Unit 3 AnnualReportoftheEmergencyCoreCoolingSystem EvaluationModelChangesand Errors Attachment3 AssessmentsasofAugust 12,2024 GNF2PeakCladdingTemperatu re RackUp SheetforPBAPS Unit3 Pa ge1of1

PLANTNAME: PeachBottomAtomicPowerStation,Unit3 ECCSEVALUATIONMODEL: SAFER/PRIME REPORTREVISIONDATE: 08/12/2024 EVALUATION MODELVENDOR: GNF/GEH CURRENTOPERATINGCYCLE: 25

ANALYSIS OFRECORDCALCULATIONS

1. ProjectTa s kRe po r t,ExelonGenerationCompanyLLC,Pe a c hBottomAto m i cPo we r Station,Units2&3MELLLA+Ta s kT0407:ECCSLO C APe r fo r m a n c e ,000001622354R0, Revi si o n0,(PLM000N0296Revi si o n0), December2013.

FuelsAnalyzedinCalculationsandinOperation: GNF2 LimitingFuelTy p e  : GNF2 LimitingSingleFailure: BatteryFailure LimitingBreakLocation: RecirculationDischargeLine LimitingBreakSize 0.05 ft2(SmallBreak)

ReferencePe a kCladdingTe m p e r a t u r e(PCT)fo rGNF2Fuel:1920°F MARGINALLOCATION A. PRIORLO CAASSESSMENTS(Note1) 10 CFR50.46Repo rtdated August15,2014(Note1.1) GNF2: PCT =5°F 10 CFR50.46Repo rtdated August10,2016(Note1.2) GNF2: PCT =0°F 10 CFR50.46Repo rtdated August10,2017(Note1.3) GNF2: PCT =0°F 10 CFR50.46Repo rtdated August10,2018(Note1.4) GNF2: PCT =0°F 10 CFR50.46Repo rtdated August12,2019(Note1.5) GNF2: PCT =0°F 10 CFR50.46Repo rtdated August12,2020(Note1.6) GNF2:PCT =0°F 10 CFR50.46Repo rt(30Day Repo rt)datedNovember05, 2020 GNF2: PCT =37°F (Note1.7) 10 CFR50.46Repo rtdated August12,2021(Note1.8) GNF2:PCT =0°F 10 CFR50.46Repo rtdated August12,2022(Note1.9) GNF2:PCT =0°F 10 CFR50.46Repo rtdated August14,2023(Note1.10) GNF2:PCT =0°F NetPCT GNF2: 1962°F

B. CURRENTLO C AASSESSMENTS(Note2)

To t a lPCTChangefromCurrentAssessments(Note2) GNF2: PCT=0°F Cumulative PCTChangefromCurrentAssessments GNF2: lPCTl =0°F NetPCT GNF2: 1962°F ATTACHMENT 4

GNF3 Peak Cladding Temperature Rack- Up Sheet for PBAPS Unit 3 AnnualReportoftheEmergencyCoreCoolingSystem EvaluationModelChangesand Errors AssessmentsasofAugust 12,2024 Atta c h m e nt4 GNF3PeakCladdingTemperatu re RackUp SheetforPBAPS Unit3 Pa ge1of1

PLANTNAME: PeachBottomAtomicPowerStation,Unit3 ECCSEVALUATIONMODEL: SAFER/PRIME REPORTREVISIONDATE: 08/12/2024 EVALUATION MODELVENDOR: GNF/GEH CURRENTOPERATINGCYCLE: 25

ANALYSIS OFRECORDCALCULATIONS

1. Pea chBottomAto m i cPo werStationUnits2&3GNF3ECCSLO C A Eva l u a t i o n ,005N9630R0, Rev is io n 0, April2021.

FuelsAnalyzedinCalculationsandinOperation: GNF3 LimitingFuelTy p e  : GNF3 LimitingSingleFailure: BatteryFailure LimitingBreakLocation: RecirculationDischargeLine LimitingBreakSize 0.05 ft2(SmallBreak)

ReferencePe a kCladdingTe m p e r a t u r e(PCT)fo rGNF3Fuel:2040°F

MARGINALLOCATION A. PRIORLO CAASSESSMENTS(Note1)

10 CFR50.46Repo rtdated August12,2022(Note1.9) GNF3: PCT =0°F 10 CFR50.46Repo rtdated August14,2023(Note1.10) GNF3: PCT =0°F

NetPCT GNF3: 2040°F

B. CURRENTLO C AASSESSMENTS(Note2)

To t a lPCTChangefromCurrentAssessments(Note2) GNF3: PCT=0°F Cumulative PCTChangefromCurrentAssessments GNF3: lPCTl =0°F

NetPCT GNF3: 2040°F ATTACHMENT 5

Assessment Notes for PBAPS AnnualReportoftheEmergencyCoreCoolingSystem EvaluationModelChangesand Errors AssessmentsasofAugust 12,2024 Atta c h m e nt5 AssessmentNotesforPBAPS Pa ge1of5

1. PriorLO C AAssessments The last 10 CFR 50.46 annual report was submitted to the U.S . NRC on August 14, 2023 (Reference 1). This reportdocumentsaGNF2fuelNetPCTof1962°F; aLicensing BasisPCTof1920°Ffromtheanalysisofrecord report, and a total PCT adder of +42°F at Pea ch Bottom Ato m i c Power Station (PBAPS), Units 2 and 3. The reportalsodocumentsaGNF3fuelNetPCTof2040°F; aLicensing BasisPCTof2040°F, andatotalPCTadder of0°FatPeachBottomAto m i cPo werStation(PBAPS)Unit 3.All thelistedpriorLO C Aassessments beloware documentedin thereferencedletter.

[Reference1:LetterfromDavidP.Helker (ConstellationEnergyGeneration,LLC)toU.S .NuclearReg ulato r y Commission,10CFR50.46 AnnualRe p o rt,dated August 14, 2023.]

1.1. PriorLO C AAssessment-2014 Thereferencedletterreportedfo u rvendornotificationsthatwerereceived.Theerrornotifications reportedinthereferencedletter areapplicabletothePea chBo ttom2and3MELLLA+ LOCAanalysisand arebeingreportedas thenotificationswerereportedpriortoimplementationoftheMELLLA+ LO C A analysis. ThenotificationswereissuedsubsequenttotheperformanceoftheMELLLA+ LOCAanalysis, but priortoitsimplementation.

1. The first notification addressed several accumulated updates to the SAFER04A model. The code maintenance changes had an individually and collectively insignificant effect on calculated peak claddingtemperature.

2. The second notification was fo r a co rrection to a logic error that was isolated, occurring with an indication that the exp ec ted systems mass diverged from the calculated actual system mass. This error affected the Emergency Core Cooling System (ECCS) flow credited as reaching the core.

Correctionofthiserrorresultedina+10°FPea kCladdingTe m p e r a t u r e(PCT) changeforGNF2fuel.

3. The third notification addressed an error with the imposed minimum Pressure Differential (p) for droplet flow above a twophase level in the core. This error could have offered an inappropriate steam cooling benefit above the core two phase level. To correct this error an expli cit core pressure dropcalculation wasapplied withoutregardtodroplet condition resultinginaPCTof10°FforGNF2 fuel.

4. The fo u r th notification addressed an incorrect pressure head representation when defining the Counter Current Flow Limitation (CCFL). Correction of this error resulted in a +5°F PCT change fo r GNF2fuel.

Note that the 10 CFR 50.46 notifications discussed in the referenced report are applicable to the Unit 2 andUnit3MELLLA+LO C Aanalysisandtheneteffectofthesenotificationsis+5°F

[

Reference:

LetterfromJamesBarstow(Exelon GenerationCompany,LLC)toU. S.NuclearRegulatory Commission,10CFR50.46 AnnualRe po rt,dated August 15, 2014.]

AnnualReportoftheEmergencyCoreCoolingSystem EvaluationModelChangesand Errors AssessmentsasofAugust 12,2024 Atta c h m e nt5 AssessmentNotesforPBAPS Pa ge2of5

1.2. PriorLO C AAssessment-2016 ThereferencedletterreportedthatPea chBottomUnit2andUnit3implemented MaximumExtended LoadLineLimitAnalysisPlus(MELLLA+)forwhichanewLO C Aanalysiswasperformed.Unit2andUnit 3 transitionedtoMELLLA+ operationmid cycleinApril2016andMay2016,respectively.Theerror notificationsreportedinAssessmentNote1.1areapplicabletothePea chBo ttom2and3MELLLA+

LO C Aanalysis. ThenotificationswereissuedsubsequenttotheperformanceoftheMELLLA+LO C A analysis,but priortoitsimplementation. Notethatthe10 CFR50.46 reportfrom2015wasissuedprior totheimplementationofthecurrentGNF2AORanddidnotincludeanyNotificationLettersapplicable tothecurrentAOR.

[

Reference:

LetterfromJamesBarstow(Exelon GenerationCompany,LLC)toU. S.NuclearRegulatory Commission,"10CFR50.46 AnnualRe p o rt, "datedAugust 10, 2016.]

1.3. PriorLO C AAssessment-2017 ThereferencedletterreportedtwovendornotificationsregardingEmergency CoreCooling System (ECCS)modeling changes/errorsapplicabletoPea c hBottom(Notifications201701 and201702). These notificationsdescribed issuesrelatedtotheimpropermodellingoflowertie plateleakagefortheGNF2 fueldesignandchanges tomodeling ofthefuelrodplenum fo r10x10fuel.Correctionofthese errors eachresultedin a0°FPCTchangefo rGNF2fuel.

Thereferencedletterreportedachangein theLevel3setpoint.TheimpactofthischangeontheLossof CoolantAccident(LOCA)analysiswasassessedin GNFRe po rt003N4534R0, "Peach BottomLevel3 AnalyticalLimitReduction,"datedMay25, 2016,whichconcludedthatthere isnoimpactonthe licensingbasisPCTfo rPea chBottom.

[

Reference:

LetterfromDavidT.Gudger(Exelon GenerationCompany,LLC)toU. S.NuclearRegulatory Commission,10CFR50.46 AnnualRe p o rt,dated August 10, 2017.]

1.4. PriorLOC AAssessment-2018 Thereferencedletterreportednochanges/errorsagainstthePBAPSLO C AAnalysisofRe cordduring this reportingperiod.

[

Reference:

LetterfromDavidT.Gudger(Exelon GenerationCompany,LLC)toU. S.NuclearRegulatory Commission,10CFR50.46 AnnualRe p o rt,dated August 10, 2018.]

1.5. PriorLO C AAssessment-2019 Thereferencedletterreportednochanges/errorsagainstthePBAPSLO C AAnalysisofRe cordduring this reportingperiod.

[

Reference:

LetterfromDavidT.Gudger(Exelon GenerationCompany,LLC)toU. S.NuclearRegulatory Commission,10CFR50.46 AnnualRe p o rt,dated August 12, 2019.]

AnnualReportoftheEmergencyCoreCoolingSystem EvaluationModelChangesand Errors AssessmentsasofAugust 12,2024 Atta c h m e nt5 AssessmentNotesforPBAPS Pa ge3of5

1.6. PriorLO C AAssessment-2020

Thereferencedletterreportedtwovendornotifications:

Notification201905 identifiedthattheupperandlower limitsfo rtheSAFERcodefo r wa rdand backwardbypassleakagewerecodedincorrectlyfo rthecontrolrodguide tubetoco ntrolroddrive housinginterfacebackwardleakagepath. Theerrorwasestimated tohave ze rodegreeupontheGNF2 PCT.

Notification202001 identifiedthatthePRIMEcodecontainederrorsin irradiationgrowthaftera breakaway neutronfluence,thermal conductivityapplied tothezirconiumbarrier fo rcladding temperaturedrop,andga pconductance during pelletcladding ga pclosure.Theerrorswereestimated tohave ze rodegreeimpactupontheGNF2PCT.

[

Reference:

LetterfromDavidP.Helker (ExelonGenerationCompany,LLC)toU. S.NuclearRegulatory Commission,10CFR50.46 AnnualRe p o rt,dated August 12, 2020.]

1.7. PriorLO C AAssessment-2020(30Day Repo rt)

Thereferencedletterreportedtwovendornotifications:

NotificationLetter(NL)202002 documentedthatthevendorimpactevaluationperformed inNL2014 01 was incorrect,andNL202002 providesanupdated impactevaluationfor oneoftheissuesreported in NL201401. NL201401 (AssessmentNote1.1)reportsseveralchanges,oneofwhichisregardingthe SAFERcodeerrorregardingthesubcooledwaterlevelin thedowncomer.PerNL202002,theimpact evaluationperformed for 201401 was inaccurate,especiallyfor postulated LOCAscenarioswherea twophase level establishesin thedowncomer, anexpectedresponseforsmall recirculationlinebreak scenarios.ThePeachBottomLOCAanalysisissmall breaklimitedas documentedinAttachments1and 2, andhence,NL202002 impactedthePeachBottom LOCAanalysis.

NL202002 wasissuedbythevendoras anewnotificationwithaPCTimpactof35oF. Thiswasthefirst NLfor PeachBottomsincethe2020annual report(AssessmentNote1.6), andtheabsolutevalueofthe reportedimpactwas less than50oF,therefore, typicallythisNLwouldnthaverequiredathirtyday reportingper10CFR50.46(a)(3)(ii).However,as documentedinNL202002, whilethisnotification did notaltertheSAFERcodeused inthePeachBottomLOCAevaluation(Attachments1and2), itdidalter thePCTimpact fromtheSAFERcodechangeas reportedinNL201401.Therefore,NL202002 effectivelyamendedNL201401 for PBAPS.

AnnualReportoftheEmergencyCoreCoolingSystem EvaluationModelChangesand Errors AssessmentsasofAugust 12,2024 Atta c h m e nt5 AssessmentNotesforPBAPS Pa ge4of5

SinceNL202002 notification effectively amended201401, thethirtyday reportingrequirementwas evaluatedbased upontheconditionsapplicablewhennotification201401 wasinitiallyissued.

AssessmentNote1.1documentsfo u rnotificationsreportedonAugust15,2014.Those fo u rnotifications were:

201401 =0°F, 201402 =10°F, 201403 =10°F,and, 201404 =5°F.

withatotal impactof25°F(=0+10 +l10l +5).Whenthereported201401 value(0°F)iscorrected withtheupdatedvaluefromNL202002 (35°F), thetotal impactbecomes60°F(=35 +10 +l10l +5),

whichislarger thanthe50°Fsignificancethreshold definedin 10CFR50.46(a)(3)(i)for thirtyday reporting.Therefore, thisthirtyday reportwas preparedfor PBAPSfor NL202002.

Notification202003 identifiedthatthedomepressureinputusedfor AppendixKcalculations in the currentLOCAanalysisofrecord(Attachments1and2)didnot cover operation allowed byTechnical Specifications3.4.10.APCTimpact of+2°F was reportedinNL202003 for correctingthedomepressure inputusedintheanalysis.

Asdescribed in thedescription ofNL202002, thisthirtyday reportwas preparedfor NL202002 receivedon10/07/2020.However,sinceNL202003 was issuedwithinthethirtyday reporting timeframefor NL202002, thisthirtyday reportalsoaddressedNL202003 for completeandaccurate reporting.

[

Reference:

LetterfromDavidP.Helker (ExelonGenerationCompany,LLC)toU. S.NuclearRegulatory Commission,EmergencyCoreCooling System(ECCS) LossofCoolantAccident (LOCA)10 CFR50.46 30 DayRepo rt,datedNovember 05, 2020.]

1.8. PriorLO C AAssessment-2021 Thereferencedletterreportedthree vendornotifications:

Notification202101 identifiesanerrorinthefuelrodstressandperforation modelduetoanincorrect value usedfo rthefuelpellettoplenum springconductanceinput.Theerrorwasaresultofanincorrect conversionfromSI unitsinpreparingtheinputforSAFERanalyses.The errorwasestimated tohave a ze rodegreeimpactupontheGNF2PCT.

Notification202102 identifiesanerrorintheinnercladdingsurfaceroughnessvalue inthega p conductancemodel. Aninconsistencywasidentifiedbetween theroughnessvalue usedinthefuel performancemodel PRIMEandtheinputtotheSAFERandTRACGcalculations.Theerrorwasestimated tohave aze rodegreeimpactupon theGNF2PCT.

AnnualReportoftheEmergencyCoreCoolingSystem EvaluationModelChangesand Errors AssessmentsasofAugust 12,2024 Attachment5 AssessmentNotesforPBAPS Pa ge5of5

Notification202103 identifiesthatanincorrectLowPressure CoolantInjection(LPCI)flowrate value atahigh pressure pointwasused intheinputtotheSAFERcalculations.Theerrorwas estimated tohave azerodegreeimpactupon theGNF2PCT.

[

Reference:

LetterfromDavidP.Helker (ExelonGenerationCompany,LLC)toU. S.NuclearRegulatory Commission,10CFR50.46 AnnualRe p o rt,dated August 12, 2021.]

1.9. PriorLO C AAssessment-2022 IssueReport4508795reportsthatachangein2011was made tothedecayheat(DH)inputused in nominalcalculationsfor theSAFER evaluationmodel.TheupdatedDHmodel isabestestimate decay heatcurvebasedonthe1979ANS5.1standard andconsidersSIL636.Thischangewas discovered duringreview oftheGNF3NewFuelIntroductionandadditionalvendorassessments estimated animpactof0°FupontheGNF2PCT. Thischange was alreadyincorporated intotheinitial GNF3LOCAevaluationandthereforehasnoimpactontheGNF3LOCAanalysisofrecord.

[

Reference:

LetterfromDavidP.Helker (Constellation Energy Generation,LLC)toU.S.Nuclear RegulatoryCommission,10CFR50.46AnnualRepo r t,datedAugust12, 2022.]

1.10. PriorLO C AAssessment-2023 Thereferencedletterreportedone(1)NotificationLetter:

NotificationLetter202301 identifiesanerrorintheapplicationoftheSAFERevaluationmodel.

Potential voidsin ECCSpipingcoulddelaywaterenteringthecore, orspargers,whichcouldimpact thePeakCladding Temperature(PCT).ECCSpipingistypicallyfilledwithliquidwaterfromthe systeminjectionvalvetothevessel.Thesystempressureisoftenabovethelow pressureECCS pumpshutoffheadwhilethesysteminjectionvalveisopeningfor small breaks.When thisistrue no flowcanpass through thefinal checkvalve.A delayinECCSinjectioncausedbyapotentialvoidin theECCSpipingafterthefinalcheckvalveisconsidered reportableunderinterpretationof10CFR 50.46 becauseitmay impactthesmall breakPCTresult.Theerrorwas estimated tohaveazero degreeimpactupontheGNF2andGNF3PCT.

NoadditionalECCS relatedchanges ormodificationsoccurredatPBAPSthataffectedthe assumptionsintheGNF2orGNF3LOCAanalysisofrecord.

[

Reference:

LetterfromDavidP.Helker (Constellation Energy Generation,LLC)toU.S.Nuclear RegulatoryCommission,10CFR50.46AnnualRepo r t,datedAugust14, 2023.]

2. CurrentLOCAAssessment

NonewNotificationLetterswerereceivedfromthefuelvendor sinceissuanceofthelastannual report (ReferenceinNote1.10).NoECCSrelatedchanges ormodificationshave occurredatPBAPSthataffected theassumptionsin theGNF2orGNF3LOCAanalysisofrecord.Therefore,thetotalPCTvalueof1962oF fo rGNF2atPBAPSUnits2and3, andthetotalPCTvalue of2040oFfo rGNF3atPBAPSUnits2and3 reportedinthelastannualreportisunchangedfo rthisreport.