ML24178A242
| ML24178A242 | |
| Person / Time | |
|---|---|
| Site: | Millstone, Summer, Surry, North Anna  |
| Issue date: | 06/25/2024 |
| From: | James Holloway Dominion Energy Nuclear Connecticut, Dominion Energy South Carolina, Virginia Electric & Power Co (VEPCO) |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 24-223 | |
| Download: ML24178A242 (1) | |
Text
Dominion Energy Services, Inc.
5000 Dominion Boulevard. Glen Allen, VA 23060 DominionEnergy com June 25, 2024 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.
DOMINION ENERGY SOUTH CAROLINA. INC.
VIRGINIA ELECTRIC AND POWER COMPANY MILLSTONE POWER STATION UNITS 2 AND 3 NORTH ANNA POWER STATION UNITS 1 AND 2 SURRY POWER STATION UNITS 1 AND 2 VIRGIL C. SUMMER NUCLEAR STATION UNIT 1
~
Dominion
§:9 Energy~
Serial No.: 24-223 NRA/AF: R1 Docket Nos.: 50-336/423 50-338/339 50-280/281 50-395 License Nos.: DPR-65/NPF-49 NPF-4ll DPR-32/37 NPF-12 2023 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 In accordance with 10 CFR 50.46(a)(3)(ii), Dominion Energy Nuclear Connecticut, Inc.
(DENG), Virginia Electric and Power Company (Dominion Energy) and Dominion Energy South Carolina, Inc. (DESC) hereby submit the annual summary of permanent changes to the emergency core cooling system (ECCS) evaluation models (EMs) for Millstone Power Station Units 2 (MPS2) and Unit 3 (MPS3), North Anna Power Station Units 1 (NAPS1) and Unit 2 (NAPS2), Surry Power Station Units 1 (SPS1) and Unit 2 (SPS2), and Virgil C.
Summer Nuclear Station Unit 1 (VCSNS), respectively. of this letter provides a report describing plant-specific evaluation model changes associated with the Westinghouse and Framatome Small Break Loss of Coolant Accident (SBLOCA) and Large Break Loss of Coolant Accident (LBLOCA) ECCS EMs for MPS2, MPS3, NAPS1, NAPS2, SPS1, SPS2, and VCSNS as applicable.
For 2023, the ASTRUM peak cladding temperature (PCT) Margin Utilization Tables have been removed from the LBLOCA information for MPS3, NAPS1, NAPS2, SPS1, and SPS2 because these units transitioned from ASTRUM to the Full Spectrum (FS) LOCA Region II methodology to evaluate the LBLOCA response in 2022.
Information regarding the effect of the ECCS EM changes upon the reported SBLOCA and LBLOCA analyses of record results is provided for MPS2, MPS3, NAPS1, NAPS2, SPS1, SPS2, and VCSNS in Attachments 2, 3, 4 and 5 respectively. The calculated PCT
Serial No.24-223 Docket Nos. 50-336/423/338/339/280/281/395 Page 2 of 4 for the SBLOCA and LBLOCA analyses for MPS2, MPS3, NAPS1, NAPS2, SPS1, SPS2, and VCSNS are summarized below:
Millstone Unit 2 Small break - Framatome EM:
1714°F Millstone Unit 2 Large break - Framatome EM (Zr4 fuel):
1845°F Millstone Unit 2 Large break - Framatome EM (MS fuel):
1615°F Millstone Unit 3 Small break-Westinghouse EM:
1193°F Millstone Unit 3 Westinghouse FSLOCA EM Region II Large break:
1712°F North Anna Units 1 and 2 Fuel-Vendor Independent (FVI)
Small break - Framatome EM:
1801 °F North Anna Units 1 and 2 Westinghouse FSLOCA EM Region II Large break:
1893°F Surry Units 1 and 2 FVI Small break - Framatome EM:
1694°F Surry Units 1 and 2 Westinghouse FSLOCA EM Region II Large break:
1921°F Virgil C. Summer Unit 1 Westinghouse FSLOCA EM Region I Small break:
1108°F Virgil C. Summer Unit 1 Westinghouse FSLOCA EM Region II Large break:
1879°F The LOCA results for MPS2, MPS3, NAPS1, NAPS2, SPS1, SPS2, and VCSNS are confirmed to have sufficient margin to the 2200°F limit for PCT as specified in 10 CFR 50.46. Based on the evaluation of this information and the resulting changes in the applicable licensing basis PCT results, no further action is required to demonstrate compliance with the 10 CFR 50.46 requirements.
The information contained herein satisfies the 2023 annual reporting requirements of 10 CFR 50.46(a)(3)(ii).
If you have any questions regarding this submittal, please contact Mr. Allen Fulmer at (803) 543-2501.
Respectfully, James Holloway Vice President - Nuclear Engineering and Fleet Support Dominion Energy Nuclear Connecticut, Inc.
Dominion Energy South Carolina, Inc Virginia Electric and Power Company Commitments made in this letter: None
Serial No.24-223 Docket Nos. 50-336/423/338/339/280/281 /395 Page 3 of 4 Attachments:
- 1. Report of Changes in Framatome and Westinghouse ECCS Evaluation Models
- 2. 2023 Annual Reporting of 10 CFR 50.46 Margin Utilization - Millstone Power Station Units 2 and 3
- 3. 2023 Annual Reporting of 10 CFR 50.46 Margin Utilization - North Anna Power Station Units 1 and 2
- 4. 2023 Annual Reporting of 10 CFR 50.46 Margin Utilization - Surry Power Station Units 1 and 2
- 5. 2023 Annual Reporting of 10 CFR 50.46 Margin Utilization - Virgil C. Summer Nuclear Station cc:
U. S. Nuclear Regulatory Commission, Region I Regional Administrator 475 Allendale Road, Suite 102 King of Prussia, PA 19406-1415 U. S. Nuclear Regulatory Commission, Region II Regional Administrator Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257 NRC Senior Resident Inspector Millstone Power Station NRC Senior Resident Inspector North Anna Power Station NRC Senior Resident Inspector Surry Power Station NRC Senior Resident Inspector Virgil C. Summer Power Station Mr. L. John Klos NRC Project Manager - Surry U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, MD 20852-2738
Serial No.24-223 Docket Nos. 50-336/423/338/339/280/281/395 Page 4 of 4 Mr. R. Guzman NRG Project Manager - Millstone Units 2 and 3 U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, MD 20852-2738 Mr. G. Edward Miller NRG Project Manager-North Anna and Virgil C. Summer U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, MD 20852-2738 Old Dominion Electric Cooperative Electronically Distributed G. J. Lindamood Santee Cooper - Nuclear Coordinator Electronically Distributed
Serial Number 24-223 Docket Nos. 50-336/423/338/339/280/281 /395 2023 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 REPORT OF CHANGES IN FRAMATOME AND WESTINGHOUSE ECCS EVALUATION MODELS DOMINION ENERGY NUCLEAR CONNECTICUT, INC.
VIRGINIA ELECTRIC AND POWER COMPANY DOMINION ENERGY SOUTH CAROLINA, INC.
MILLSTONE POWER STATION UNITS 2 AND 3 NORTH ANNA POWER STATION UNITS 1 AND 2 SURRY POWER STATION UNITS 1 AND 2 VIRGIL C. SUMMER NUCLEAR STATION UNIT 1
Serial Number 24-223 Docket Nos. 50-336/423/338/339/280/281 /395, Page 1 of 8 REPORT OF CHANGES IN FRAMATOME AND WESTINGHOUSE ECCS EVALUATION MODELS Millstone Power Station Unit 2
- 1.
Framatome identified no changes or errors applicable to the EMF-2328{P)(A) Revision 0 with Supplement 1 evaluation model for Small Break LOCA (SBLOCA) for Millstone Power Station Unit 2 (MPS2) during 2023.
- 2.
Framatome identified no changes or errors applicable to the SEM/PWR-98 evaluation model for Large Break LOCA (LBLOCA) for Millstone Unit 2 during 2023. This evaluation model is applicable to the Millstone Unit 2 fuel with Zr-4 cladding.
- 3.
Framatome identified the following changes applicable to the EMF-2103(P)(A), Revision 3 evaluation model for RLBLOCA applicable to the AREVA Standard CE 14 HTP fuel product with the M5 TM fuel rod cladding for Millstone Unit 2 during 2023.
Downcomer to Upper Head Bypass Error A discrepancy in the plant model used in the Millstone Unit 2 RLBLOCA Analysis of Record (AOR) with the Framatome EMF-2103(P)(A) Revision 3 Realistic Large Break LOCA (RLBLOCA) methodology was discovered. Specific design features, other than leakage paths, are required to model the downcomer to upper head bypass. The plant model erroneously only included leakage paths.
An evaluation was conducted to determine the impact of removal on the AOR. The change in peak cladding temperature (PCT) for the MPS2 RLBLOCA analysis is 0°F.
Incorrect Open Porosity value used in COPERNIC Fuel Model for LOCA Fuel Initialization Framatome identified an error in the default value used for fuel open porosity in the COPERNIC fuel model that is used in the (RLBLOCA) uncertainty analysis performed under the EMF-2103(P)(A) Revision 3 methodology. Investigation into this error identified that when the fuel performance code COPERNIC was incorporated into the RLBLOCA methodology, the default value specified for the UO2 fuel open porosity was incorrectly selected from a different fuel type. The error in the fuel open porosity impacts the LOCA fuel initial conditions determined by COPERNIC and used in the RLBLOCA uncertainty analysis.
Fuel open porosity affects the initial rod internal pressure. The correct fuel open porosity value represents a decrease from that used in the impacted RLBLOCA analyses. The evaluation considered the change in fuel open porosity to determine the impact on the fuel initial conditions. Minor differences were observed in the rod internal pressure and effectively no change in fuel initial temperatures.
Serial Number 24-223 Docket Nos. 50-336/423/338/339/280/281 /395, Page 2 of 8 Therefore, an evaluation was conducted to determine the impact of the error on the affected RLBLOCA uncertainty analyses. It was concluded that the error in the fuel open porosity has an insignificant impact on the LOCA fuel initial conditions and, as such, has an estimated PCT impact of 0°F on the RLBLOCA uncertainty analysis results.
Millstone Power Station Unit 3
- 1.
Westinghouse identified no changes or errors applicable to the 1985 Westinghouse SBLOCA Evaluation Model with NOTRUMP for Millstone Power Station Unit 3 (MPS3) during 2023.
- 2.
Westinghouse identified the following changes or errors applicable to the FSLOCA Region 2 Large Break WCAP-16996-P-A, Revision 1, "Realistic LOCA Evaluation Methodology Applied to the Full Spectrum of Break Sizes (FSLOCA)" for MPS3 during 2023.
Error in Flow Area and Volume of Thimble Components The reactor vessel thimble bypass flow is modeled in best-estimate (BE) loss-of-coolant accident (LOCA) analyses using three PIPE components, which represent the thimble bypass for peripheral low power assemblies, interior assemblies located under guide tubes, and interior assemblies not located under guide tubes. It was discovered that the number of assemblies modeled is inconsistent with the number of assemblies represented by one or more of the thimble components, leading to an incorrect flow area and volume for the affected thimble component(s).
The error was evaluated to have a negligible impact on the calculated results, leading to an estimated PCT impact of O °F.
Vapor/ Continuous Liquid lnterfacial Drag Coefficient in Churn-Turbulent Flow Regime Two deficiencies were identified in the calculation of the churn-turbulent vapor /
continuous liquid interfacial drag coefficient calculation within WCOBRA/TRAC-TF2 due to the potential calculation of a negative critical liquid fraction. The negative critical liquid fraction results in an over-prediction of the vapor/ continuous liquid interfacial area and a negative vapor I continuous liquid interfacial drag coefficient which leads to a significantly large interfacial drag coefficient (i.e., no slip).
The closely related group of deficiencies was qualitatively evaluated, and the nature of the deficiencies leads to an estimated peak cladding temperature impact of O °F.
Planned Discretionary Changes Beyond the two changes in the FSLOCA Region 2 Large Break discussed above, two discretionary changes to the WCAP-16996-P-A, Revision 1 evaluation model were
Serial Number 24-223 Docket Nos. 50-336/423/338/339/280/281 /395, Page 3 of 8 identified. These changes have not been evaluated against the MPS3 AOR but rather will be implemented on a forward fit basis in accordance with Section 4.1.1 of WCAP-13451, "Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting". As these changes have not been evaluated against the Millstone 3 AOR, they are not listed as items in the PCT margin utilization sheet.
LUCIFER Kinetics and Decay Heat Model The kinetics and decay heat model in the WCOBRA/TRAC-TF2 code has been updated since the approval of the FSLOCA EM. While the primary purpose of the kinetics and decay heat model update is to support the analysis of higher burnup fuel, the change will minimally impact licensing basis analysis calculations with the FSLOCA EM under the existing burnup limits, which was imposed via Limitation and Condition (L&C) #5 on the FSLOCA EM.
Pellet Radial Noding Consistent with PADS The fuel rod radial noding in the WCOBRA/TRAC-TF2 code is described in Sections 8.2 and 8.4 of WCAP-16996-P-A, Revision 1. The fuel rod radial noding was updated to be consistent with the PAD5 code (WCAP-17642-P-A, Revision 1) regarding the size and number of the nodes.
North Anna Power Station Units 1 and 2
- 1.
Framatome identified no changes or errors applicable to the EMF-2328(P}(A), Revision 0, PWR Small Break LOCA EM using S-RELAP5 for North Anna Power Station Unit 1 (NAPS1) and Unit 2 (NAPS2) during 2023.
- 2.
Westinghouse identified the following changes or errors applicable to the WCAP-16996-P-A FSLOCA Region II Large Break EM for NAPS1 and NAPS2 during 2023.
Vapor/ Continuous Liquid lnterfacial Drag Coefficient in Churn-Turbulent Flow Regime Two deficiencies were identified in the calculation of the churn-turbulent vapor /
continuous liquid interfacial drag coefficient calculation within WCOBRA/TRAC-TF2 due to the potential calculation of a negative critical liquid fraction. The negative critical liquid fraction results in an over-prediction of the vapor/ continuous liquid interfacial area and a negative vapor / continuous liquid interfacial drag coefficient which leads to a significantly large interfacial drag coefficient (i.e., no slip}.
The closely related group of deficiencies was qualitatively evaluated, and the nature of the deficiencies leads to an estimated peak cladding temperature impact of O °F.
Planned Discretionary Changes Serial Number 24-223 Docket Nos. 50-336/423/338/339/280/281 /395, Page 4 of 8 Beyond the change in the FSLOCA Region 2 Large Break discussed above, two discretionary changes to the WCAP-16996-P-A, Revision 1 evaluation model were identified. These changes have not been evaluated against the NAPS1/NAPS2 AOR, but instead they will be implemented on a forward fit basis in accordance with Section 4.1.1 of WCAP-13451, "Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting". As these changes have not been evaluated against the NAPS1/NAPS2 AOR, they are not listed as items in the PCT margin utilization sheets.
LUCIFER Kinetics and Decay Heat Model The kinetics and decay heat model in the WCOBRA/TRAC-TF2 code has been updated since the approval of the FSLOCA EM. While the primary purpose of the kinetics and decay heat model update is to support the analysis of higher burnup fuel, the change will minimally impact licensing basis analysis calculations with the FSLOCA EM under the existing burnup limits, which was imposed via Limitation and Condition (L&C) #5 on the FSLOCA EM.
Pellet Radial Noding Consistent with PADS The fuel rod radial noding in the WCOBRA/TRAC-TF2 code is described in Sections 8.2 and 8.4 of WCAP-16996-P-A, Revision 1. The fuel rod radial noding was updated to be consistent with the PAD5 code (WCAP-17642-P-A, Revision 1) regarding the size and number of the nodes.
Surry Power Station Units 1 and 2
- 1.
Framatome identified no changes or errors applicable to the EMF-2328(P)(A), Revision 0, PWR Small Break LOCA EM using S-RELAP5 for Surry Power Station Unit 1 (SPS1) and Unit 2 (SPS2) during 2023:
- 2.
Westinghouse identified the following changes or errors applicable to the FSLOCA Region 2 Large Break WCAP-16996-P-A, Revision 1, "Realistic LOCA Evaluation Methodology Applied to the Full Spectrum of Break Sizes (FSLOCA)" for Surry Units 1 and 2 during 2023.
Error in Flow Area and Volume of Thimble Components The reactor vessel thimble bypass flow is modeled in best-estimate (BE) loss-of-coolant accident (LOCA) analyses using three PIPE components, which represent the thimble bypass for peripheral low power assemblies, interior assemblies located under guide tubes, and interior assemblies not located under guide tubes. It was discovered that the number of assemblies modeled is inconsistent with the number of assemblies represented by one or more of the thimble components, leading to an incorrect flow area and volume for the affected thimble component(s).
Serial Number 24-223 Docket Nos. 50-336/423/338/339/280/281/395, Page 5 of 8 The error was evaluated to have a negligible impact on the calculated results, leading to an estimated PCT impact of O °F.
Vapor I Continuous Liquid lnterfacial Drag Coefficient in Churn-Turbulent Flow Regime Two deficiencies were identified in the calculation of the churn-turbulent vapor /
continuous liquid interfacial drag coefficient calculation within WCOBRA/TRAC-TF2 due to the potential calculation of a negative critical liquid fraction. The negative critical liquid fraction results in an over-prediction of the vapor/ continuous liquid interfacial area and a negative vapor / continuous liquid interfacial drag coefficient which leads to a significantly large interfacial drag coefficient (i.e., no slip).
The closely related group of deficiencies was qualitatively evaluated, and the nature of the deficiencies leads to an estimated peak cladding temperature impact of O °F.
Planned Discretionary Changes Beyond the two changes in the FSLOCA Region 2 Large Break discussed above, two discretionary changes to the WCAP-16996-P-A, Revision 1 evaluation model were identified. These changes have not been evaluated against the SPS1 and SPS2 AOR, but instead they will be implemented on a forward fit basis in accordance with Section 4.1.1 of WCAP-13451, "Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting". As these changes have not been evaluated against the SPS1 and SPS2 AOR, they are not listed as items in the PCT margin utilization sheets.
LUCIFER Kinetics and Decay Heat Model The kinetics and decay heat model in the WCOBRA/TRAC-TF2 code was updated since the approval of the FSLOCA EM. While the primary purpose of the kinetics and decay heat model update is to support the analysis of higher burnup fuel, the change will minimally impact licensing basis analysis calculations with the FSLOCA EM under the existing burnup limits, which was imposed via Limitation and Condition (L&C) #5 on the FSLOCA EM.
Pellet Radial Noding Consistent with PADS The fuel rod radial noding in the WCOBRA/TRAC-TF2 code is described in Sections 8.2 and 8.4 of WCAP-16996-P-A, Revision 1. The fuel rod radial noding was updated to be consistent with the PAD5 code (WCAP-17642-P-A, Revision 1) regarding the size and number of the nodes.
Virgil C. Summer Serial Number 24-223 Docket Nos. 50-336/423/338/339/280/281 /395, Page 6 of 8
- 1.
Westinghouse identified the following changes or errors applicable to the WCAP-16996-P-A FSLOCA Region I Small Break EM for Virgil C. Summer Nuclear Station (VCSNS) during 2023.
Vapor/ Continuous Liquid lnterfacial Drag Coefficient in Churn-Turbulent Flow Regime Two deficiencies were identified in the calculation of the churn-turbulent vapor /
continuous liquid interfacial drag coefficient calculation within WCOBRAffRAC-TF2 due to the potential calculation of a negative critical liquid fraction. The negative critical liquid fraction results in an over-prediction of the vapor/ continuous liquid interfacial area and a negative vapor / continuous liquid interfacial drag coefficient which leads to a significantly large interfacial drag coefficient (i.e., no slip).
The closely related group of deficiencies was qualitatively evaluated, and the nature of the deficiencies leads to an estimated peak cladding temperature impact of O °F.
Planned Discretionary Changes Beyond the change in the FSLOCA Region 1 Small Break discussed above, two discretionary changes to the WCAP-16996-P-A, Revision 1 evaluation model were identified. These changes have not been evaluated against the VCSNS AOR, but instead they will be implemented on a forward fit basis in accordance with Section 4.1.1 of WCAP-13451, "Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting". As these changes have not been evaluated against the VCSNS AOR, they are not listed as items in the PCT margin utilization sheets.
LUCIFER Kinetics and Decay Heat Model The kinetics and decay heat model in the WCOBRAffRAC-TF2 code was updated since the approval of the FSLOCA EM. While the primary purpose of the kinetics and decay heat model update is to support the analysis of higher burnup fuel, the change will minimally impact licensing basis analysis calculations with the FSLOCA EM under the existing burnup limits, which was imposed via Limitation and Condition (L&C) #5 on the FSLOCA EM.
Pellet Radial Noding Consistent with PADS The fuel rod radial noding in the WCOBRA/TRAC-TF2 code is described in Sections 8.2 and 8.4 of WCAP-16996-P-A, Revision 1. The fuel rod radial noding was updated to be consistent with the PADS code {WCAP-17642-P-A, Revision 1) regarding the size and number of the nodes.
Serial Number 24-223 Docket Nos. 50-336/423/338/339/280/281/395, Page 7 of 8
- 2.
Westinghouse identified the following changes or errors applicable to the WCAP-16996-P-A FSLOCA Region II Large Break EM for VCSNS during 2023.
Vapor/ Continuous Liquid lnterfacial Drag Coefficient in Churn-Turbulent Flow Regime Two deficiencies were identified in the calculation of the churn-turbulent vapor /
continuous liquid interfacial drag coefficient calculation within WCOBRA/TRAC-TF2 due to the potential calculation of a negative critical liquid fraction. The negative critical liquid fraction results in an over-prediction of the vapor/ continuous liquid interfacial area and a negative vapor / continuous liquid interfacial drag coefficient which leads to a significantly large interfacial drag coefficient (i.e., no slip).
The closely related group of deficiencies was qualitatively evaluated, and the nature of the deficiencies leads to an estimated peak cladding temperature impact of O °F.
Planned Discretionary Changes Beyond the change in the FSLOCA Region 2 Large Break discussed above, two discretionary changes to the WCAP-16996-P-A, Revision 1 evaluation model were identified. These changes have not been evaluated against the VCSNS AOR, but instead they will be implemented on a forward fit basis in accordance with Section 4.1.1 of WCAP-13451, "Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting". As these changes have not been evaluated against the VCSNS AOR, they are not listed as items in the PCT margin utilization sheets.
LUCIFER Kinetics and Decay Heat Model The kinetics and decay heat model in the WCOBRA/TRAC-TF2 code was updated since the approval of the FSLOCA EM. While the primary purpose of the kinetics and decay heat model update is to support the analysis of higher burnup fuel, the change will minimally impact licensing basis analysis calculations with the FSLOCA EM under the existing burnup limits, which was imposed via Limitation and Condition (L&C) #5 on the FSLOCA EM.
Pellet Radial Noding Consistent with PADS The fuel rod radial noding in the WCOBRA/TRAC-TF2 code is described in Sections 8.2 and 8.4 of WCAP-16996-P-A, Revision 1. The fuel rod radial noding was updated to be consistent with the PAD5 code (WCAP-17642-P-A, Revision 1) regarding the size and number of the nodes.
Conclusion The LOCA results for MPS2, MPS3, NAPS1, NAPS2, SPS1, SPS2, and VCSNS are confirmed in the PCT margin utilization tables, Attachments 2 through 5, to have margin to the 2200°F limit
Serial Number 24-223 Docket Nos. 50-336/423/338/339/280/281/395, Page 8 of 8 for PCT specified in 10 CFR 50.46. Based on the evaluation of this information and the resulting changes in the applicable licensing basis PCT results, no further action is required to demonstrate compliance with the 10 CFR 50.46 requirements. Reporting of this information is required per 10 CFR 50.46(a)(3)(ii), which obligates each licensee to report the effect upon calculated temperature of any change or error in evaluation models or their application on an annual basis.
This information satisfies the annual reporting requirements of 10 CFR 50.46(a)(3)(ii) for calendar year 2023.
Serial Number 24-223 Docket Nos. 50-336/423 2023 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 2023 ANNUAL REPORTING OF 10 CFR 50.46 MARGIN UTILIZATION DOMINION ENERGY NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNITS 2 AND 3
10 CFR 50.46 MARGIN UTILIZATION - SMALL BREAK LOCA Plant Name:
Millstone Power Station, Unit 2 Utility Name:
Dominion Energy Nuclear Connecticut, Inc.
Analysis Information Serial Number 24-223 Docket Nos. 50-336/423, Page 1 of 5 EM:
2015, Supp. l, SBLOCA, S-RELAP5 Based Limiting Break Size: 3. 78 Inches Analysis Date:
April 2015 Vendor:
AREY A Peak Linear Power:
15.1 kW/ft Notes:
None Clad Temp(0 F)
LICENSING BASIS Analysis of Record PCT 1707 PCT ASSESSMENTS (Delta PCT)
A.
Prior ECCS Model Assessments
- l.
Zirc-4 Product Penalty 4
- 2.
MS LOCA Swelling and Rupture 0
- 3.
S-RELAP5 Oxidation Calculations 3
B.
Planned Plant Modification Evaluations
- 1.
None 0
C.
2023 ECCS Model Assessments
- l.
None 0
D.
Other
- l.
None 0
LICENSING BASIS PCT+ PCT ASSESSMENTS PCT=
1714
Serial Number 24-223 Docket Nos. 50-336/423, Page 2 of 5 10 CFR 50.46 MARGIN UTILIZATION - LARGE BREAK LOCA Plant Name:
Millstone Power Station, Unit 2 Utility Name:
Dominion Energy Nuclear Connecticut, Inc.
Analysis Information EM:
SENf/PWR-98 Limiting Break Size:
1.0 DECLG Analysis Date:
November 1998 AREVA Vendor:
Peak Linear Power:
15.1 kW/ft None Notes:
Clad Temp{°F)
LICENSING BASIS Analysis of Record PCT 1814 PCT ASSESSMENTS (Delta PCT)
A.
Prior ECCS Model Assessments
- l.
Corrected Corrosion Enhancement Factor
-1
- 2.
ICECON Coding Errors 0
- 3.
Setting RFPAC Fuel Temperatures at Start ofReflood
-2
- 4.
SISPUNCH/ujun98 Code Error 0
- 5.
Error in Flow Blockage Model in TOODEE2 0
- 6.
Change in TOODEE2-Calculation ofQMAX 0
- 7.
Change in Gadolinia Modeling 0
- 8.
PWR LBLOCA Split Break Modeling 0
- 9.
TEOBY Calculation Error 0
l 0.
Inappropriate Heat Transfer in TOODEE2 0
- 11.
End-of-Bypass Prediction by TEOBY 0
- 12.
R4SS Overwrite of Junction Inertia 0
- 13.
Incorrect Junction Inertia Multipliers l
- 14.
Errors Discovered During RODEX2 V & V 0
- 15.
Error in Broken Loop SG Tube Exit Junction Inertia 0
- 16.
Rf PAC Refill and Reflood Calculation Code Errors 16
- 17.
Incorrect Pump Junction Area Used in RELAP4 0
- 18.
Error in TOODEE2 Clad The1mal Expansion
-1
- 19.
Accumulator Line Loss Error
-1
- 20.
Inconsistent Loss Coefficients Used for Robinson LBLOCA 0
- 21.
Pump Head Adjustment for Pressure Balance Initialization
-3
- 22.
ICECON Code Errors 0
- 23.
Containment Sump Modification and Replacement PZR 2
- 24.
Non-Conservative RODEX Fuel Pellet Temperature 20
- 25.
Array Index Issues in the RELAP4 Code 0
B.
Planned Plant Modification Evaluations
- 1.
None 0
C.
2023 ECCS Model Assessments
- l. None 0
D.
Other
- 1.
None 0
LICENSING BASIS PCT+ PCT ASSESSMENTS PCT=
1845
10 CFR 50.46 MARGIN UTILIZATION - LARGE BREAK LOCA Plant Name:
Utility Name:
Millstone Power Station, Unit 2 (MS Fuel)
Dominion Energy Nuclear Connecticut, Inc.
Serial Number 24-223 Docket Nos. 50-336/423, Page 3 of 5 Analysis Information EM:
EMF-2103 January 2017 AREVA Limiting Break Size:
1.0 DEGB Analysis Date:
Vendor:
Peak Linear Power:
15.1 kW/ft None Notes:
LICENSING BASIS Analysis of Record PCT PCT ASSESSMENTS (Delta PCT)
A.
Prior ECCS Mode) Assessments
- 1.
Placement of Hot Leg Piping Form Loss Coefficient
- 2.
MS LOCA Swelling and Rupture
- 3.
S-RELAPS Oxidation Calculations
- 4.
Cathcart-Pawel correlation implementation
- 5.
Rod pressure not reset after rupture in S-RELAPS LOCA calculations
- 6.
Radiation enclosure input error B.
Planned Plant Modification Evaluations
- 1.
None C.
2023 ECCS Model Assessments
- 1.
Downcomer to upper head bypass error
- 2.
Fuel model open porosity input error D.
Other
- 1.
None LICENSING BASIS PCT+ PCT ASSESSMENTS PCT=
Clad Temp(0F) 1615 0
0 0
0 0
0 0
0 0
0 1615
10 CFR 50.46 MARGIN UTILIZATION - SMALL BREAK LOCA Plant Name:
Utility Name:
Analysis Information EM:
Analysis Date:
Vendor:
Millstone Power Station, Unit 3 Dominion Energy Nuclear Connecticut, Inc.
Limiting Break Size:
Serial Number 24-223 Docket Nos. 50-336/423, Page 4 of 5 4 inches FQ:
NOTRUMP 02/07/07 Westinghouse 2.6 FdH:
1.65 Fuel:
RFA-2 SGTP (%):
10 Notes:
None LICENSING BASIS Analysis of Record PCT PCT ASSESSMENTS (Delta PCT)
A.
Prior ECCS Model Assessments
- 1.
Errors in Reactor Vessel Lower Plenum Surface Area Calculations
- 2.
Discrepancy in Metal Masses Used From Drawings
- 3.
Urania-Gadolinia Pellet Thermal Conductivity Calculation
- 4.
Pellet Crack and Dish Volume Calculation
- 5.
Treatment of Vessel Average Temperature Uncertainty
- 6.
Maximum Fuel Rod Time Step Logic
- 7.
Radiation Heat Transfer Logic
- 8.
NOTRUMP-EM Evaluation of Fuel Pellet Thermal
- 9.
- 10.
- 11.
- 12.
Conductivity Degradation SBLOCTA Cladding Strain Requirement for Fuel Rod Burst Fuel Rod Gap Conductance Error Radiation Heat Transfer Model Error SBLOCTA Pre-DNB Cladding Heat Transfer Coefficient Calculation Insertion of AXIOMrn Cladding LT As Vessel Average Temperature Uncertainty Error in the Upper Plenum Fluid Volume Calculation UO2 Fuel Pellet Heat Capacity Small Break LOCA PADS Implementation
- 13.
- 14.
- 15.
- 16.
- 17.
- 18.
Reduction in Flow Area to the Bottom of the Barrel/Baffle Region
- 19.
Measurement Uncertainty Recapture Uprate B.
Planned Plant Modification Evaluations
- 1.
None C.
2023 ECCS Model Assessments
- 1.
None D.
Other I.
None LICENSING BASIS PCT+ PCT ASSESS IENTS PCT=
Clad Temp (0 F) 1193 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
1193
10 CFR 50.46 MARGIN UTILIZATION - LARGE BREAK LOCA Plant Name:
Utility Name:
Analysis Information EM:
Analysis Date:
Vendor:
Millstone Power Station, Unit 3 Dominion Energy Nuclear Connecticut, Inc.
FSLOCA (Region II)
October 2020 Westinghouse Limiting Break Size:
Serial Number 24-223 Docket Nos. 50-336/423, Page 5 of 5 Guillotine FQ:
2.6 FdH:
1.65 Fuel:
RFA-2 SGTP (%):
.:s:;10 Notes:
None LICENSING BASIS Analysis of Record PCT PCT ASSESSMENTS (Delta PCT)
A.
Prior ECCS Model Assessments B.
C.
- 1.
- 2.
Non-Conservation of Energy in the Generalized Energy Deposition Model Error in Hoop Stress Used in Cladding Rupture Model Planned Plant Modification Evaluations
- 1.
None 2023 ECCS Model Assessments
- 1.
Error in Flow Area and Volume of Thimble Components D.
- 2.
Vapor/ Continuous Liquid Interfacial Drag Coefficient in Chum-Turbulent Flow Regime Other
- 1.
None LICENSING BASIS PCT+ PCT ASSESSMENTS PCT=
Clad Temp{°F) 1712 0
0 0
0 0
0 1712
ATTACHMENT 3 Serial Number 24-223 Docket Nos. 50-338/339 2023 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 2023 ANNUAL REPORTING OF 10 CFR 50.46 MARGIN UTILIZATION VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2
Serial Number 24-223 Docket Nos. 50-338/339, Page 1 of 4 10 CFR 50.46 l\,lARGIN UTILIZATION - FRAMATOME FVI SMALL BREAK LOCA Plant Name:
Utility Name:
Analysis Information North Anna Power Station, Unit 1 Virginia Electric and Power Company EM:
W&CE SBLOCA EMF-2328 Limiting Break Size:
6.5 inches Analysis Date:
Vendor:
FQ:
Fuel:
Notes:
LICENSING BASIS May 2018 Framatome 2.5 Representative l 7xl 7 Non-MS None Analysis of Record PCT PCT ASSESSMENTS (Delta PCT)
A.
Prior ECCS Model Assessments
- 1.
None B.
Planned Plant Modification Evaluations
- 1.
None C.
2023 ECCS Model Assessments
- 1.
None D.
Other
- 1.
None LICENSING BASIS PCT+ PCT ASSESSMENTS FMI:
SGTP(%):
1.65 7
PCT=
Clad Temp{°F) 1801 0
0 0
0 1801
Serial Number 24-223 Docket Nos. 50-338/339, Page 2 of 4 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE LARGE BREAK LOCA Plant Name:
Utility Name:
North Anna Power Station, Unit I Virginia Electric and Power Company Analysis Information EM:
FSLOCA (Region II)
August2019 Westinghouse Limiting Break Size:
Analysis Date:
Vendor:
FQ:
2.5 FMI:
1.70 Fuel:
RFA-2 SGTP (%):
- -S 2%
LICENSING BASIS Analysis of Record PCT PCT ASSESSMENTS (Delta PCT)
A.
Prior ECCS Model Assessments B.
C.
- 1.
Evaluation of Containment Spray Flow Increase
- 2.
Error in Hoop Stress used in Cladding Rupture Model
- 3.
Non-Conservation of Energy in the Generalized Energy Deposition Model Planned Plant Modification Evaluations
- 1.
None 2023 ECCS Model Assessments
- 1.
Vapor/ Continuous Liquid lnterfacial Drag Coefficient in Chum-Turbulent Flow Regime D.
Other
- l.
None LICENSING BASIS PCT+ PCT ASSESSMENTS PCT=
DEGB Clad Temp {°F}
1893 0
0 0
0 0
1893
Serial Number 24-223 Docket Nos. 50-338/339, Page 3 of 4 10 CFR 50.46 MARGIN UTILIZATION - FRAMATOME FYI SMALL BREAK LOCA Plant Name:
Utility Name:
Analvsis Information North Anna Power Station, Unit 2 Virginia Electric and Power Company EM:
W&CE SBLOCA EMF-2328 Limiting Break Size:
6.5 inches Analysis Date:
Vendor:
FQ:
Fuel:
Notes:
LICENSING BASIS May2018 Framatome 2.5 FMI:
Representative l 7xl 7 Non-M5 SGTP (% ):
None Analysis of Record PCT PCT ASSESSMENTS (Delta PCT)
A.
Prior ECCS Model Assessments
- 1.
None B.
Planned Plant Modification Evaluations
- 1.
None C.
2023 ECCS Model Assessments
- 1.
None D.
Other
- 1.
None LICENSING BASIS PCT+ PCT ASSESSMENTS 1.65 7
PCT=
Clad Temp {°F) 1801 0
0 0
0 1801
Serial Number 24-223 Docket Nos. 50-338/339, Page 4 of 4 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE LARGE BREAK LOCA Plant Name:
Utility Name:
North Anna Power Station, Unit 2 Virginia Electric and Power Company Analysis Information EM:
FSLOCA (Region II)
August 2019 Westinghouse Limiting Break Size:
Analysis Date:
Vendor:
FQ:
2.5 FMI:
1.70 Fuel:
RFA-2 SGTP (%):
- '.S 2%
LICENSING BASIS Analysis of Record PCT PCT ASSESSlVIENTS (Delta PCT)
A.
Prior ECCS Model Assessments B.
C.
- 1.
Evaluation of Containment Spray Flow Increase
- 2.
Error in Hoop Stress used in Cladding Rupture Model
- 3.
Non-Conservation of Energy in the Generalized Energy Deposition Model Planned Plant Modification Evaluations
- 1.
None 2023 ECCS Model Assessments
- 1.
Vapor/ Continuous Liquid lnterfacial Drag Coefficient in Chum-Turbulent Flow Regime D.
Other
- 1.
None LICENSING BASIS PCT+ PCT ASSESSMENTS PCT=
DEGB Clad Temp {°F) 1893 0
0 0
0 0
1893
ATTACHMENT 4 Serial Number 24-223 Docket Nos. 50-280/281 2023 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 2023 ANNUAL REPORTING OF 10 CFR 50.46 MARGIN UTILIZATION VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2
Serial Number 24-223 Docket Nos. 50-280/281, Page 1 of 4 10 CFR 50.46 MARGIN UTILIZATION - FRAMATOME FVI SMALL BREAK LOCA Plant Name:
Surry Power Station, Unit 1 Utility Name:
Virginia Electric and Power Company Analysis Information EM:
W&CE SBLOCA EMF-2328 Analysis Date:
July 2018 Framatome
2.5 Vendor
FQ:
Fuel:
Notes:
Representative 15xl5 Non-MS None LICENSING BASIS Analysis of Record PCT PCT ASSESSMENTS (Delta PCT)
A.
Prior ECCS Model Assessments B.
C.
D.
- 1.
SBLOCA Rod History Truncation (FVI-SBLOCA downflow baffle)
- 2.
Upflow Baffle Modification Planned Plant Modification Evaluations
- 1.
None 2023 ECCS Model Assessments
- 1.
None Other
- 1.
None LICENSING BASIS PCT + PCT ASSESSMENTS Limiting Break Size: 2.6 inches FMI:
SGTP(%):
1.70 7
PCT=
Clad Temp (
0 F) 1673 0
21 0
0 0
1694
Serial Number 24-223 Docket Nos. 50-280/281, Page 2 of 4 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE LARGE BREAK LOCA Plant Name:
Surry Power Station, Unit I Utility Name:
Virginia Electric and Power Company Analysis Information EM:
FSLOCA (Region II)
August 2019 Westinghouse Limiting Break Size:
Analysis Date:
Vendor:
FQ:
~2.5 FMI:
- 1.7 Fuel
Upgrade SGTP (%):
- 7 Notes
None LICENSING BASIS Analysis of Record PCT PCT ASSESSMENTS (Delta PCT)
A.
B.
C.
Prior ECCS Model Assessments
- l.
Advanced Debris Filter Bottom Nozzle Large Break LOCA Evaluation
- 2.
- 3.
- 4.
- 5.
- 6.
Upflow Conversion Evaluation of Containment Spray Flow Increase Error in Hoop Stress used in Cladding Rupture Model Non-Conservation of Energy in the Generalized Energy Deposition Model Reduction of Total Core Peaking Factor Surveillance Uncertainty Planned Plant Modification Evaluations
- 1.
None 2023 ECCS Model Assessments
- 1.
Error in Flow Area and Volume of Thimble Components D.
- 2.
Vapor/ Continuous Liquid Interfacial Drag Coefficient in Chum-Turbulent Flow Regime Other
- 1.
None LICENSING BASIS PCT+ PCT ASSESSMENTS PCT=
DEG Clad Temp {0 F) 1875 0
46 0
0 0
0 0
0 0
0 1921
Serial Number 24-223 Docket Nos. 50-280/281, Page 3 of 4 10 CFR 50.46 l\llARGIN UTILIZATION - FRAMATOME FVI SMALL BREAK LOCA Plant Name:
Surry Power Station, Unit 2 Utility Name:
Virginia Electric and Power Company Analvsis Information EM:
W&CE SBLOCA EMF-2328 Limiting Break Size: 2.6 inches Analysis Date:
July 2018 Framatome Vendor:
FQ:
2.5 FAfl:
Fuel:
Representative 15xl5 Non-MS SGTP (%):
Notes:
None LICENSING BASIS Analysis of Record PCT PCT ASSESSMENTS (Delta PCT)
A.
Prior ECCS Model Assessments B.
C.
D.
- 1.
SBLOCA Rod History Truncation (FVI-SBLOCA downflow baffle)
- 2.
Upflow Baffle Modification Planned Plant Modification Evaluations
- 1.
None 2023 ECCS Model Assessments
- 1.
None Other
- 1.
None LICENSING BASIS PCT+ PCT ASSESSMENTS 1.70 7
PCT=
CladTempf°F) 1673 0
21 0
0 0
1694
Serial Number 24-223 Docket Nos. 50-280/281, Page 4 of 4 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE LARGE BREAK LOCA Plant Name:
Surry Power Station, Unit 2 Utility Name:
Virginia Electric and Power Company Analysis Information EM:
FSLOCA (Region II)
August 2019 Westinghouse Limiting Break Size:
Analysis Date:
Vendor:
FQ:
S2.5 FMI:
- S 1.7 Fuel:
Upgrade SGTP (%):
- S7 Notes:
None LICENSING BASIS Analysis of Record PCT PCT ASSESSMENTS (Delta PCT)
A.
B.
- c.
Prior ECCS Model Assessments
- 1.
Advanced Debris Filter Bottom Nozzle Large Break LOCA Evaluation
- 2.
- 3.
- 4.
- 5.
- 6.
Upflow Conversion Evaluation of Containment Spray Flow Increase Error in Hoop Stress used in Cladding Rupture Model Non-Conservation of Energy in the Generalized Energy Deposition Model Reduction of Total Core Peaking Factor Surveillance Uncertainty Planned Plant Modification Evaluations
- l.
None 2023 ECCS Model Assessments
- l.
Error in Flow Area and Volume of Thimble Components D.
- 2.
Vapor/ Continuous Liquid Interfacial Drag Coefficient in Chum-Turbulent Flow Regime Other
- l.
None LICENSING BASIS PCT+ PCT ASSESSMENTS PCT=
DEG Clad Temp (
0 F) 1875 0
46 0
0 0
0 0
0 0
0 1921
ATTACHMENT 5 Serial Number 24-223 Docket Nos. 50-395 2023 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 2023 ANNUAL REPORTING OF 10 CFR 50.46 MARGIN UTILIZATION DOMINION ENERGY SOUTH CAROLINA, INC.
VIRGIL C. SUMMER NUCLEAR STATION UNIT 1
Serial Number 24-223 Docket Nos. 50-395, Page 1 of 2 10 CFR 50.46 Margin Utilization - WESTINGHOUSE Small Break LOCA Plant Name:
V. C. Summer Utility Name:
Dominion Energy South Carolina Analysis Information EM:
FSLOCA (Region I)
January 2019 Westinghouse Limiting Break Size:
Analysis Date:
Vendor:
FQ:
2.5 FdH:
Notes:
None LICENSING BASIS Analysis of Record PCT (Including gamma energy redistribution)
A.
B.
C.
D.
Prior ECCS Model Assessments
- 1.
En-or in Hoop Stress used in Cladding Rupture Model
- 2.
Non-Conservation of Energy in the Generalized Energy Deposition Model Planned Plant Modification Evaluations
- 1.
None 2023 ECCS Model Assessments
- l.
Vapor/ Continuous Liquid Interfacial Drag Coefficient in Chum-Turbulent Flow Regime Other
- 1.
None LICENSING BASIS PCT+ PCT ASSESSMENTS 1.70 PCT=
2.6 Inch Clad Temp(0 F) 1108 0
0 0
0 0
1108
Serial Number 24-223 Docket Nos. 50-395, Page 2 of 2 10 CFR 50.46 Margin Utilization - WESTINGHOUSE Large Break LOCA Plant Name:
V. C. Summer Utility Name:
Dominion Energy South Carolina Analysis Information EM:
FSLOCA (Region II)
January 2019 Westinghouse Limiting Break Size:
Analysis Date:
Vendor:
FQ:
2.5 FdH:
Notes:
None LICENSING BASIS Analysis of Record PCT (Including gamma energy redistribution)
A.
Prior ECCS Model Assessments B.
C.
D.
1.
Error in Hoop Stress used in Cladding Rupture Model 2.
Non-Conservation of Energy in the Generalized Energy Deposition Model Planned Plant Modification Evaluations 1.
None 2023 ECCS Model Assessments 1.
Vapor/ Continuous Liquid Interfacial Drag Coefficient in Chum-Turbulent Flow Regime Other 1.
None LICENSING BASIS PCT+ PCT ASSESSMENTS 1.70 PCT=
DEGB Clad Temp(0F) 1879 0
0 0
0 0
1879