RA-19-0223, Annual Report of Changes to or Errors in Emergency Core Cooling System Evaluation Models Pursuant to 10CFR 50.46

Annual Report of Changes to or Errors in Emergency Core Cooling System Evaluation Models Pursuant to 10CFR 50.46

ML19150A112
Person / Time
Site:	Oconee, Mcguire, Catawba, Harris, Brunswick, Robinson, McGuire
Issue date:	05/30/2019
From:	Snider S Duke Energy Corp
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RA-19-0223
Download: ML19150A112 (25)

Text

Steve Snider Vice President Nuclear Engineering 526 South Church Street, EC-07H Charlotte, NC 28202 980-373-6195 Steve.Snider@duke-energy.com 10 CFR 50.46 May 30, 2019 Serial: RA-19-0223 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Brunswick Steam Electric Plant, Unit Nos. 1 and 2 Renewed Facility Operating License Nos. DPR-71 and DPR-62 Docket Nos. 50-325 and 50-324 Catawba Nuclear Station, Unit Nos. 1 and 2 Renewed Facility Operating License Nos. NPF-35 and NPF-52 Docket Nos. 50-413 and 50-414 H. B. Robinson Steam Electric Plant, Unit 2 Renewed Facility Operating License No. DPR-23 Docket No. 50-261 McGuire Nuclear Station, Unit Nos. 1 and 2 Renewed Facility Operating License Nos. NPF-9 and NPF-17 Docket Nos. 50-369 and 50-370 Shearon Harris Nuclear Power Plant, Unit 1 Renewed Facility Operating License No. NPF-63 Docket No. 50-400 Oconee Nuclear Station, Unit Nos. 1, 2 and 3 Renewed Facility Operating License Nos. DPR-38, DPR-47 and DPR-55 Docket Nos. 50-269, 50-270 and 50-287

Subject:

Annual Report of Changes Pursuant to 10 CFR 50.46 Ladies and Gentlemen:

Pursuant to 10 CFR 50.46(a)(3)(ii), Duke Energy hereby submits the enclosed annual reports of changes to or errors in Emergency Core Cooling System (ECCS) evaluation models. These reports cover the period from January 1, 2018 to December 31, 2018 for the Brunswick Steam Electric Plant, Catawba Nuclear Station, H. B. Robinson Steam Electric Plant, McGuire Nuclear Station, Shearon Harris Nuclear Power Plant and the Oconee Nuclear Station.

There are no regulatory commitments contained in this letter.

U.S. Nuclear Regulatory Commission Page 2 Serial: RA-19-0223 Should you have any questio ns concerning this letter and its enclosu res, please contact Art Zaremba, Manager - Nuclea r Fleet Licensing at (980) 373-2062.

Sincerely, Steve Snider Vice President - Nuclear Engineering JLV

Enclosures:

1. Brunswick 10 CFR 50.46 Annual Report

2. Catawba 10 CFR 50.46 Annual Report

3. Robinson 10 CFR 50.46 Annual Report

4. McGuire 10 CFR 50.46 Annual Report

5. Shearon Harris 10 CFR 50.46 Annual Report

6. Oconee 10 CFR 50.46 Annual Report cc: Ms. C. Haney, NRC Regional Administrator, Region II Mr. D. J. Galvin, NRC Project Manager, BNP Mr. G. Smith, NRC Sr. Resident Inspector, BNP Mr. M. Mahoney, NRC Project Manager, CNS and MNS Mr. J. D. Austin, NRC Sr. Resident Inspector, CNS Mr. A. Hutto, NRC Sr. Resident Inspector, MNS Mr. N. Jordan, NRC Project Manager, HBRSEP2 Mr. M. Fannon, NRC Sr. Resident Inspector, HBRSE P2 Ms. M. Barillas, NRC Project Manager, HNP Mr. J. Zeiler, NRC Sr. Resident Inspector, HNP Ms. A. Klett, NRC Senior Project Manager, ONS Mr. E. L. Crowe, NRC Sr. Resident Inspector, ONS Chair - North Carolina Utilities Commission (Electronic Copy Only)

Ms. L. Garner, Manager, SC DHEC Ms. A. Nair-Gimmi, SC DHEC Mr. A. Wilson, Attorney General (SC)

U.S. Nuclear Regulatory Commission Page 3 Serial: RA-19-0223 bcc (with Enclosure):

W.R. Gideon K.K. Moser J. Ratliff J.L. Pierce T. Simril C.E. Curry A.B. Linker M.B. Hare E. Kapopoulos J.A. Krakuszeski B.J. Foster K.M. Ellis T. Ray E.R. Pigott N.E. Kunkel J. Thomas T.M. Hamilton J. Dills C. Kidd B.C. McCabe E. Burchfield P.V. Fisk T. Grant S.A. Dalton S. Snider M.C. Nolan A.H. Zaremba S.B. Thomas M.C. Handrick D.A. Cummings ELL File: (Corporate)

U.S. Nuclear Regulatory Commission Page 1 of 3 Serial: RA-19-0223 Serial: RA-19-0223 Brunswick Steam Electric Plant, Units 1 and 2 Docket Nos. 50-325 and 50-324 / Renewed License Nos. DPR-71 and DPR-62 Enclosure 1 Brunswick 10 CFR 50.46 Annual Report

U.S. Nuclear Regulatory Commission Page 2 of 3 Serial: RA-19-0223 A10XM Summary 10 CFR 50.46 Report for Brunswick Steam Electric Plant Units 1, and 2 Plant: Brunswick Steam Electric Plant, Units 1 and 2 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if applicable):

Evaluation Model: EMF-2361(P)(A), Revision 0 EXEM BWR-2000 ECCS Evaluation Model, May 2001 Fuel: ATRIUM 10XM (A10XM)

A. Analysis of Record PCT 1923 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported 0 °F 0 °F C. Baseline PCT for assessing new changes for significance (A + B) 1923 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. Error in the Thermal Conductivity 0 °F Degradation analysis for top lattices with a top peaked axial power shape. BNPs limiting lattice is a bottom lattice with a mid- peaked axial power shape -

no impact. (Framatome Report FS1-0040060 Rev. 1.0).

E. Sum of 10 CFR 50.46 Changes and Net PCT Effect Absolute PCT Effect Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 1923 °F

U.S. Nuclear Regulatory Commission Page 3 of 3 Serial: RA-19-0223 ATRIUM 11 Summary 10 CFR 50.46 Report for Brunswick Steam Electric Plant Units 1, and 2 Plant: Brunswick Steam Electric Plant, Unit 2 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if applicable):

Evaluation Model: EMF-2361(P)(A), Revision 0 EXEM BWR-2000 ECCS Evaluation Model, May 2001 Fuel: ATRIUM 11 (A11)

A. Analysis of Record PCT 1762 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported 0 °F 0 °F C. Baseline PCT for assessing new changes for significance (A + B) 1762 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. Error in the Thermal Conductivity 0 °F Degradation analysis for top lattices with a top peaked axial power shape. BNPs limiting lattice is a bottom lattice with a mid- peaked axial power shape -

no impact. (Framatome Report FS1-0041575 Rev. 1.0).

E. Sum of 10 CFR 50.46 Changes and Net PCT Effect Absolute PCT Effect Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 1762 °F

U.S. Nuclear Regulatory Commission Page 1 of 6 Serial: RA-19-0223 Serial: RA-19-0223 Catawba Nuclear Station, Units 1 and 2 Docket Nos. 50-413 and 50-414 / Renewed License Nos. NPF-35 and NPF-52 Enclosure 2 Catawba 10 CFR 50.46 Annual Report

U.S. Nuclear Regulatory Commission Page 2 of 6 Serial: RA-19-0223 Westinghouse identified and communicated in a letter that there were modeling changes and errors in the LOCA evaluation models that were assessed for impact to PCT in 2018. None of the assessments resulted in changes to PCT. The following items are included for information.

VAPOR TEMPERATURE RESETTING Affected Evaluation Model(s):

1996 Westinghouse Best Estimate Large Break LOCA In the WCOBRA/TRAC and WCOBRA/TRAC-TF2 codes, when the vapor temperature is greater than the wall temperature, and several other conditions are met, the vapor temperature is reset to the saturation temperature for heat transfer calculations. It was discovered that this vapor temperature resetting logic results in an inconsistency between the conduction solution and the hydraulic solution, such that energy is not conserved between the two solutions. The correction of this error represents a Non-Discretionary Change in the Evaluation Model as described in Section 4.1.2 of WCAP-13451.

Engineering judgement supported by sensitivity calculations showed that correcting this error had minimal impact on LOCA transient calculations, leading to an estimated peak cladding temperature impact of 0 °F.

UO2 Fuel Pellet Heat Capacity Affected Evaluation Model: 1985 Westinghouse Small Break LOCA Evaluation Model with NOTRUMP A typographical error was discovered in the implementation of the UO2 fuel pellet heat capacity as described by Equation C-4 of WCAP-8301 [1] for fuel rod heat-up calculations within the Appendix K Large Break and Small Break LOCA evaluation models. The erroneous formulation results in an overprediction of heat capacity that increases with fuel temperature. The corrected formulation results in a maximum decrease in heat capacity on the order of approximately 1.2%

for existing analyses of record. This represents a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451.

The small over-prediction in UO2 fuel pellet heat capacity has been evaluated to have a negligible effect on existing large and small break LOCA analysis results due to the small magnitude of the change, leading to an estimated PCT impact of 0 °F.

Reference

1) WCAP-8301, LOCTA-IV Program: Loss-of-Coolant Transient Analysis, June 1974.

U.S. Nuclear Regulatory Commission Page 3 of 6 Serial: RA-19-0223 10 CFR 50.46 Report for Catawba Unit 1 - Large Break LOCA Plant: Catawba Nuclear Station, Unit 1 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if applicable): Large Break Evaluation Model: WCAP-12945-P-A, Revision 0 Code Qualification Document for Best Estimate LOCA Analysis Fuel: 17x17 RFA A. Analysis of Record PCT 2028 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +58 °F 378 °F C. Baseline PCT for assessing new changes for significance (A + B) 2086 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. Vapor Temperature Resetting 0 °F E. Sum of 10 CFR 50.46 Changes and Net PCT Effect Absolute PCT Effect Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 2086 °F

U.S. Nuclear Regulatory Commission Page 4 of 6 Serial: RA-19-0223 10 CFR 50.46 Report for Catawba Unit 1 - Small Break LOCA Plant: Catawba Nuclear Station, Unit 1 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if applicable): Small Break Evaluation Model: WCAP-10054-P-A, Revision 0 NOTRUMP Fuel: 17x17 RFA A. Analysis of Record PCT 1323 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +0 °F 0 °F C. Baseline PCT for assessing new changes for significance (A + B) 1323 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. UO2 Fuel Pellet Heat Capacity 0 °F E. Sum of 10 CFR 50.46 Changes and Net PCT Effect Absolute PCT Effect Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 1323 °F

U.S. Nuclear Regulatory Commission Page 5 of 6 Serial: RA-19-0223 10 CFR 50.46 Report for Catawba Unit 2 - Large Break LOCA Plant: Catawba Nuclear Station, Unit 2 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if applicable): Large Break Evaluation Model: WCAP-12945-P-A, Revision 0 Code Qualification Document for Best Estimate LOCA Analysis Fuel: 17x17 RFA A. Analysis of Record PCT 2028 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +42 °F 362 °F C. Baseline PCT for assessing new changes for significance (A + B) 2070 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. Vapor Temperature Resetting 0 °F E. Sum of 10 CFR 50.46 Changes and Net PCT Effect Absolute PCT Effect Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 2070 °F

U.S. Nuclear Regulatory Commission Page 6 of 6 Serial: RA-19-0223 10 CFR 50.46 Report for Catawba Unit 2 - Small Break LOCA Plant: Catawba Nuclear Station, Unit 2 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if applicable): Small Break Evaluation Model: WCAP-10054-P-A, Revision 0 NOTRUMP Fuel: 17x17 RFA A. Analysis of Record PCT 1243 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +0 °F 0 °F C. Baseline PCT for assessing new changes for significance (A + B) 1243 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. UO2 Fuel Pellet Heat Capacity 0 °F E. Sum of 10 CFR 50.46 Changes and Net PCT Effect Absolute PCT Effect Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 1243 °F

U.S. Nuclear Regulatory Commission Page 1 of 3 Serial: RA-19-0223 Serial: RA-19-0223 H. B. Robinson Steam Electric Plant, Unit 2 Docket No. 50-261 / Renewed License No. DPR-23 Enclosure 3 Robinson 10 CFR 50.46 Annual Report

U.S. Nuclear Regulatory Commission Page 2 of 3 Serial: RA-19-0223 10 CFR 50.46 Report for H. B. Robinson Unit 2 - Large Break LOCA Plant: H. B. Robinson , Unit 2 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if Large Break applicable):

Evaluation Model: EMF-2103(P)(A), Revision 0 Realistic Large Break LOCA for PWRs Fuel: 15x15 HTP A. Analysis of Record PCT 2084 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +4 °F 24 °F C. Baseline PCT for assessing new changes for significance (A + B) 2088 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. Estimated effect of including a +31 °F fuel clad swelling and rupture model, inclusive of (1) M5 LOCA swelling and rupture model update and (2) error corrections to cladding oxidation calculation due to use of cold cladding dimensions.

E. Sum of 10 CFR 50.46 Changes Net PCT Effect Absolute PCT Effect and Error Corrections against Baseline PCT +31 °F 31 °F F. Licensing Basis PCT (C + E) 2119 °F

U.S. Nuclear Regulatory Commission Page 3 of 3 Serial: RA-19-0223 10 CFR 50.46 Report for H. B. Robinson Unit 2 - Small Break LOCA Plant: H. B. Robinson , Unit 2 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if Small Break applicable):

Evaluation Model: EMF-2328(P)(A), Revision 0 PWR Small Break LOCA Evaluation Model Fuel: 15x15 HTP A. Analysis of Record PCT 1492 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +60 °F 98 °F C. Baseline PCT for assessing new changes for significance (A + B) 1552 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. None E. Sum of 10 CFR 50.46 Changes Net PCT Effect Absolute PCT Effect and Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 1552 °F

U.S. Nuclear Regulatory Commission Page 1 of 4 Serial: RA-19-0223 Serial: RA-19-0223 McGuire Nuclear Station, Units 1 and 2 Docket Nos. 50-369 and 50-370 / Renewed License Nos. NPF-9 and NPF-17 Enclosure 4 McGuire 10 CFR 50.46 Annual Report

U.S. Nuclear Regulatory Commission Page 2 of 4 Serial: RA-19-0223 Westinghouse identified and communicated in a letter that there were modeling changes and errors in the LOCA evaluation models that were assessed for impact to PCT in 2018. None of the assessments resulted in changes to PCT. The following items are included for information.

VAPOR TEMPERATURE RESETTING Affected Evaluation Model(s):

1996 Westinghouse Best Estimate Large Break LOCA In the WCOBRA/TRAC and WCOBRA/TRAC-TF2 codes, when the vapor temperature is greater than the wall temperature, and several other conditions are met, the vapor temperature is reset to the saturation temperature for heat transfer calculations. It was discovered that this vapor temperature resetting logic results in an inconsistency between the conduction solution and the hydraulic solution, such that energy is not conserved between the two solutions. The correction of this error represents a Non-Discretionary Change in the Evaluation Model as described in Section 4.1.2 of WCAP-13451.

Engineering judgement supported by sensitivity calculations showed that correcting this error had minimal impact on LOCA transient calculations, leading to an estimated peak cladding temperature impact of 0 °F.

UO2 Fuel Pellet Heat Capacity Affected Evaluation Model: 1985 Westinghouse Small Break LOCA Evaluation Model with NOTRUMP A typographical error was discovered in the implementation of the UO2 fuel pellet heat capacity as described by Equation C-4 of WCAP-8301 [1] for fuel rod heat-up calculations within the Appendix K Large Break and Small Break LOCA evaluation models. The erroneous formulation results in an overprediction of heat capacity that increases with fuel temperature. The corrected formulation results in a maximum decrease in heat capacity on the order of approximately 1.2%

for existing analyses of record. This represents a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451.

The small over-prediction in UO2 fuel pellet heat capacity has been evaluated to have a negligible effect on existing large and small break LOCA analysis results due to the small magnitude of the change, leading to an estimated PCT impact of 0 °F.

Reference

1) WCAP-8301, LOCTA-IV Program: Loss-of-Coolant Transient Analysis, June 1974.

U.S. Nuclear Regulatory Commission Page 3 of 4 Serial: RA-19-0223 10 CFR 50.46 Report for McGuire Units 1 & 2 - Large Break LOCA Plant: McGuire Nuclear Station, Units 1 & 2 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if applicable): Large Break Evaluation Model: WCAP-12945-P-A, Revision 0 Code Qualification Document for Best Estimate LOCA Analysis Fuel: 17x17 RFA A. Analysis of Record PCT 2028 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +58 °F 378 °F C. Baseline PCT for assessing new changes for significance (A + B) 2086 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. Vapor Temperature Resetting 0 °F E. Sum of 10 CFR 50.46 Changes and Net PCT Effect Absolute PCT Effect Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 2086 °F

U.S. Nuclear Regulatory Commission Page 4 of 4 Serial: RA-19-0223 10 CFR 50.46 Report for McGuire Units 1 & 2 - Small Break LOCA Plant: McGuire Nuclear Station, Units 1 & 2 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if applicable): Small Break Evaluation Model: WCAP-10054-P-A, Revision 0 NOTRUMP Fuel: 17x17 RFA A. Analysis of Record PCT 1323 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +0 °F 0 °F C. Baseline PCT for assessing new changes for significance (A + B) 1323 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. UO2 Fuel Pellet Heat Capacity 0 °F E. Sum of 10 CFR 50.46 Changes and Net PCT Effect Absolute PCT Effect Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 1323 °F

U.S. Nuclear Regulatory Commission Page 1 of 3 Serial: RA-19-0223 Serial: RA-19-0223 Shearon Harris Nuclear Power Plant, Unit 1 Docket No. 50-400 / Renewed License No. NPF-63 Enclosure 5 Shearon Harris 10 CFR 50.46 Annual Report

U.S. Nuclear Regulatory Commission Page 2 of 3 Serial: RA-19-0223 10 CFR 50.46 Report for Shearon Harris Unit 1 - Large Break LOCA Plant: Shearon Harris, Unit 1 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if Large Break applicable):

Evaluation Model: EMF-2103(P)(A), Revision 0 Realistic Large Break LOCA for PWRs Fuel: 17x17 HTP A. Analysis of Record PCT 1935 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +160 °F 160 °F C. Baseline PCT for assessing new changes for significance (A + B) 2095 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. None E. Sum of 10 CFR 50.46 Changes Net PCT Effect Absolute PCT Effect and Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 2095 °F

U.S. Nuclear Regulatory Commission Page 3 of 3 Serial: RA-19-0223 10 CFR 50.46 Report for Shearon Harris Unit 1 - Small Break LOCA Plant: Shearon Harris, Unit 1 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if Small Break applicable):

Evaluation Model: EMF-2328(P)(A), Revision 0 PWR Small Break LOCA Evaluation Model Fuel: 17x17 HTP A. Analysis of Record PCT 1664 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +63 °F 63 °F C. Baseline PCT for assessing new changes for significance (A + B) 1727 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. None E. Sum of 10 CFR 50.46 Changes Net PCT Effect Absolute PCT Effect and Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 1727 °F

U.S. Nuclear Regulatory Commission Page 1 of 3 Serial: RA-19-0223 Serial: RA-19-0223 Oconee Nuclear Station, Units 1, 2 and 3 Docket Nos. 50-269, 50-270 and 50-287 Renewed License Nos. DPR-38, DPR-47 and DPR-55 Enclosure 6 Oconee 10 CFR 50.46 Annual Report

U.S. Nuclear Regulatory Commission Page 2 of 3 Serial: RA-19-0223 10 CFR 50.46 Report for Oconee Units 1, 2, & 3 - Large Break LOCA Plant: Oconee Nuclear Station, Units 1, 2, & 3 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if applicable): Large Break Evaluation Model: BAW-10192P-A, Revision 0, BWNT LOCA Evaluation Model for Once-Through Steam Generator Plants Fuel: 15x15 Mark-B-HTP A. Analysis of Record PCT 1852 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +2 °F 858 °F C. Baseline PCT for assessing new changes for significance (A + B) 1854 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. None E. Sum of 10 CFR 50.46 Changes and Net PCT Effect Absolute PCT Effect Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 1854 °F

U.S. Nuclear Regulatory Commission Page 3 of 3 Serial: RA-19-0223 10 CFR 50.46 Report for Oconee Units 1, 2, & 3 - Small Break LOCA Plant: Oconee Nuclear Station, Units 1, 2, & 3 Reporting Period: January 1, 2018 - December 31, 2018 LOCA Analysis Type (if applicable): Small Break Evaluation Model: BAW-10192P-A, Revision 0, BWNT LOCA Evaluation Model for Once-Through Steam Generator Plants Fuel: 15x15 Mark-B-HTP A. Analysis of Record PCT 1598 °F Full Power (FP) - 100% FP B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +0 °F 0°F C. Baseline PCT for assessing new changes for significance (A + B) 1598 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. None E. Sum of 10 CFR 50.46 Changes and Net PCT Effect Absolute PCT Effect Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 1598 °F A. Analysis of Record PCT 1480 °F Reduced Power - 50% FP B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +0 °F 0°F C. Baseline PCT for assessing new changes for significance (A + B) 1480 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. None E. Sum of 10 CFR 50.46 Changes and Net PCT Effect Absolute PCT Effect Error Corrections against Baseline PCT 0 °F 0 °F F. Licensing Basis PCT (C + E) 1480 °F