ML19179A147

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2018 Annual Report of Emergency Core Cooling System (ECCS) Model Changes Pursuant to the Requirements of 10 CFR 50.46
ML19179A147
Person / Time
Site: Millstone, Surry, North Anna  Dominion icon.png
Issue date: 06/21/2019
From: Mark D. Sartain
Dominion Energy Nuclear Connecticut, Dominion Energy Services, Virginia Electric & Power Co (VEPCO)
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
19-246
Download: ML19179A147 (30)
v • d • e


Text

Dominion Energy Services, Inc.

5000 Dominion Boulevard, Glen Allen, VA 23060 ~ Dominion Dominion Energy.com ~ Energy June 21, 2019 10 CFR 50.46 U.S. Nuclear Regulatory Commission Serial No.: 19-246 Attention: Document Control Desk NRA/GDM: RO Washington, DC 20555 Docket Nos.: 50-336/423 50-338/339 50-280/281 License Nos.: DPR-65/NPF-49 NPF-4/7 DPR-32/37 DOMINION ENERGY NUCLEAR CONNECTICUT, INCORPORATED (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 2018 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) and Virginia Electric and Power Company (Dominion Energy Virginia) hereby submit the annual summary of permanent changes to the ECCS evaluation models (EMs) for Millstone Power Station (MPS) Units 2 and 3, North Anna Power Station (NAPS) Units

  • 1 and 2, and Surry Power Station (SPS) Units 1 and 2, respectively.

Attc;1chment 1 to this letter provides a report describing* plant-specific EM 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 MPS 2 and 3, NAPS 1 and 2, and SPS 1 and_ 2, as applicable.

Information regarding the effect of the ECCS EM changes upon the reported SBLOCA and LBLOCA analyses of record results is provided for MPS 2 and 3, NAPS 1 and 2,

  • and 2 in Attachments 2, 3, and 4, respectively. The calculated Peak Cladding Temperatures (PCT) for the SBLOCA and LBLOCA analyses for MPS 2 and 3, NAPS 1 and 2, and SPS 1 and 2 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 (M5 fuel): 1615°F Millstone Unit 3 Small Break - Westinghouse EM: 1193°F

  • Millstone Unit 3 Large Break - Westinghouse EM: 1933°F North Anna Units 1 and 2 Small Break - Westinghouse EM: 1834.1°F North Anna Units 1 and 2 Large Break - Westinghouse EM: 1982°F Surry Units 1 and 2 Small Break - Westinghouse EM: 2012°F Surry Units 1 arid 2 Large Break - Westinghouse EM: 2071 °F

Serial No.19-246 Docket Nos. 50-336/423/338/339/280/281 10 CFR 50.46 Annual Report Page 2 of 3 The LOCA results for MPS 2 and 3, NAPS 1 and 2, and SPS 1 and 2 are confirmed to have sufficient margin to the 2200°F limit 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.

The information contained herein satisfies the 2018 annual reporting requirements of 10 CFR 50.46(a)(3)(ii).

If you have any questions regarding this submittal, please contact Mr. Gary D. Miller at (804) 273-2771.

Respectfully, Mark D. Sartain Vice President - Nuclear Engineering and Fleet Support Dominion Energy Nuclear Connecticut, Inc.

Virginia Electric and Power Company Commitments made in this letter: None Attachments:

1. Report of Changes in Framatome and Westinghouse ECCS Evaluation Models
2. 2018 Annual Reporting of 10 CFR 50.46 Margin Utilization - Millstone Power Station Units 2 and 3
3. 2018 Annual Reporting of 10 CFR 50.46 Margin Utilization - North Anna Power Station Units 1 and 2
4. 2018 Annual Reporting of 10 CFR 50.46 Margin Utilization - Surry Power Station Units 1 and 2

Serial No.19-246 Docket Nos. 50-336/423/338/339/280/281 10 CFR 50.46 Annual Report Page 3 of 3 cc: U. S. Nuclear Regulatory Commission, Region I Regional Administrator 2100 Renaissance Blvd., Suite 100 King of Prussia, PA 19406-2713 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 G. Edward Miller NRC Senior Project Manager - North Anna Units 1 and 2 U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 B1-A 11555 Rockville Pike Rockville, MD 20852-2738 R. V. Guzman NRC Senior Project Manager - Millstone Units 2 and 3 U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 C-2 11555 Rockville Pike Rockville, MD 20852-2738 K. R. Cotton Gross NRC Project Manager - Surry Units 1 and 2 U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G-9A 11555 Rockville Pike Rockville, MD 20852-2738 M. Harris Old Dominion Electric Cooperative Innsbrook Corporate Center, Suite 300 4201 Dominion Blvd.

Glen Allen, Virginia 23060

Serial Number 19-246 Docket Nos. 50-336/423/338/339/280/281 Attachment 1 2018 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 MILLSTONE POWER STATION UNITS 2 AND 3 NORTH ANNA POWER STATION UNITS 1 AND 2 SURRY POWER STATION UNITS 1 AND 2

Serial Number 19-246 Docket Nos. 50-336/423/338/339/280/281 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 Unit 2 during 2018.

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 2018. This evaluation model is applicable to the Millstone Unit 2 fuel with Zr-4 cladding.

3. On January 24, 2017, a new LBLOCA analysis was approved by the NRG, based upon the EMF-2103(P)(A), Revision 3, "Realistic Large Break LOCA (RLBLOCA)

Methodology for Pressurized Water Reactors." The new analysis is applicable to the Framatome Standard CE14 HTP fuel product with the M5' fuel rod cladding.

Framatome identified no changes or errors applicable to the EMF-2103(P)(A),

Revision 3, evaluation model for RLBLOCA for Millstone Unit 2 during 2018.

Millstone Power Station Unit 3

1. Westinghouse identified the following change and error applicable to the 1985 Westinghouse SBLOCA Evaluation Model (EM) with NOTRUMP for Millstone Unit 3 during 2018:
  • U02 FUEL PELLET HEAT CAPACITY. A typographical error was discovered in the implementation of the U02 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 EMs. 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.

The small overprediction in U02 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 Peak Clad Temperature (PCT) impact of 0°F.

2. .Westinghouse identified the following changes and errors applicable to the 2004 Westinghouse Best Estimate (BE) LBLOCA EM using the Automated Statistical Treatment of Uncertainty Method (ASTRUM) for Millstone Unit 3 during 2018:
  • VAPOR TEMPERATURE RESETTING. 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 Page 1 of 4

Serial Number 19-246 Docket Nos. 50-336/423/338/339/280/281 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. 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.

  • MILLSTONE UNIT 3 CYCLE 20 PBOT/PMID VIOLATIONS. The Millstone Unit 3 Cycle 20 reload core design resulted in violations of the PBOT/PMID box used in the LBLOCA analysis. These violations were evaluated for Millstone Unit 3 Cycle 20 operation. This item represents a change in plant configuration or associated set points, distinguished from an EM change in Section 4 of WCAP-13451. The PCT impact of the PBOT/PMID violations for Millstone Unit 3 Cycle 20 was determined via a plant-specific evaluation to be 0°F.

Cycle 20 operation began in spring 2019, and thus the evaluation is included as a planned modification in Attachment 2.

North Anna Power Station Units 1 and 2

1. Westinghouse identified the following change and error applicable to the 1985 Westinghouse SBLOCA EM with NOTRUMP for North Anna Units 1 and 2 during 2018:
  • U02 FUEL PELLET HEAT CAPACITY. A typographical error was discovered in the implementation of the U02 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 EMs. 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.

The small over-prediction in U02 fuel pellet heat capacity has been evaluated to have a negligible effect on existing Large Break and Small Break LOCA analysis results due to the small magnitude of the change, leading to an estimated PCT impact of 0°F.

2. Westinghouse identified the following change and error applicable to the 2004 Westinghouse BE LBLOCA EM using ASTRUM for North Anna Units 1 and 2 during 2018:
  • VAPOR TEMPERATURE RESETTING. 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 Page 2 of 4

Serial Number 19-246 Docket Nos. 50-336/423/338/339/280/281 inconsistency between the conduction solution and the hydraulic solution, such that energy is not conserved between the two solutions. 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.

Surry Power Station Units 1 and 2

1. Westinghouse identified the following change and error applicable to the 1985 Westinghouse SBLOCA EM with NOTRUMP for Surry Units 1 and 2 during 2018:
  • U02 FUEL PELLET HEAT CAPACITY. A typographical error was discovered in the implementation of the U02 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 EMs. 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.

The small overprediction in U02 fuel pellet heat capacity has been evaluated to have a negligible effect on existing Large Break and Small Break LOCA analysis results due to the small magnitude of the change leading to an estimated PCT impact of 0°F.

2. Westinghouse identified the following change and error applicable to the 2004 Westinghouse BE LBLOCA EM using ASTRUM for Surry Units 1 and 2 during 2018:
  • VAPOR TEMPERATURE RESETTING. 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. 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.

Conclusion The LOCA results for Millstone Units 2 and 3, North Anna Units 1 and 2, and Surry Units 1 and 2 are confirmed in the PCT rackup tables, Attachments 2 through 4, to have margin to the 2200°F limit 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),

Page 3 of 4

Serial Number 19-246 Docket Nos. 50-336/423/338/339/280/281 which obligates each licensee to report the effect upon calculated temperature of any change or error in EMs 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 2018.

Reference:

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

Page 4 of 4

Serial Number 19-246 Docket Nos. 50-336/423 Attachment 2 2018 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 2018 ANNUAL REPORTING OF 10 CFR 50.46 MARGIN UTILIZATION DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNITS 2 AND 3

Serial Number 19-246 Docket Nos. 50~336/423 Attachment 2 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 EM: 2015, Supp. 1, SBLOCA, S-RELAP5 Based Limiting Break Size: 3.78 Inches Analysis Date: April 2015 Vendor: Framatome Peak Linear Power: 15.1 kW/ft Notes: None Clad Temp (°F)

LICENSING BASIS Analysis of Record PCT 1707 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

.1. Zirc-4 Product Penalty 4

2. M5 LOCA Swelling and Rupture 0
3. S-RELAP5 Oxidation Calculations 3 B. Planned Plant Modification Evaluations
1. None 0 C. 2018 ECCS Model Assessments
1. None 0 D. Other
1. None 0 LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 1714 Page 1 of 7

Serial Number 19-246 Docket Nos. 50-336/423 Attachment 2 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: SEM/PWR-98 Limiting Break Size: 1.0 DECLO Analysis Date: November 1998 Vendor: Framatome Peak Linear Power: 15 .1 kW/ft Notes: None Clad Temp (°F)

LICENSING BASIS Analysis of Record PCT 1814 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

1. 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 of QMAX 0
7. Change in Oadolinia Modeling 0
8. PWR LBLOCA Split Break Modeling 0
9. TEOBY Calculation Error 0
10. 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 1
14. Errors Discovered During RODEX2 V & V 0
15. Error in Broken Loop SO Tube Exit Junction Inertia 0
16. RFP AC Refill and Reflood Calculation Code Errors 16
17. Incorrect Pump Junction Area Used in RELAP4 0
18. Error in TOODEE2 Clad Thermal Expansion -1
19. Accumulator Line Loss Error -1
20. Inconsistent Loss Coefficients Used for Robinson LBLOCA 0
21. Pump Head Adjustment for Pressure Balance Ini'tialization -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. Millstone Unit 3 Cycle 20 PBOT/PMID Violations 0 C. 2018 ECCS Model Assessments
1. None 0 Page 2 of 7

Serial Number 19-246 Docket Nos. 50-336/423 Attachment 2 D. Other

1. None 0 LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 1845 Page 3 of 7

Serial Number 19-246 Docket Nos. 50-336/423 Attachment 2 10 CFR 50.46 MARGIN UTILIZATION - LARGE BREAK LOCA Plant Name: Millstone Power Station, Unit 2 (M5 Fuel)

Utility Name: Dominion Energy Nuclear Connecticut, Inc.

Analysis Information EM: EMF-2103 Limiting Break Size: 1.0 DEGB Analysis Date: January 2017 Vendor: Frarnatome Peak Linear Power: 15 .1 kW/ft Notes: None Clad Temp (°F)

LICENSING BASIS Analysis of Record PCT 1615 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

1. Placement of Hot Leg Piping Form Loss Coefficient 0
2. MS LOCA Swelling and Rupture 0
3. S-RELAP5 Oxidation Calculations 0 B. Planned Plant Modification Evaluations
1. None 0 C. 2018 ECCS Model Assessments
1. None 0 D. Other
1. None 0 LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 1615 Page 4 of 7 J

Serial Number 19-246 Docket Nos. 50-336/423 Attachment 2 10 CFR 50.46 MARGIN UTILIZATION - SMALL BREAK LOCA Plant Name: Millstone Power Station, Unit 3 Utility Name: Dominion Energy Nuclear Connecticut, Inc.

Analysis Information EM: NOTRUMP Limiting Break Size: 4 inches Analysis Date: 02/07/07 Vendor: Westinghouse FQ: 2.6 FdH: 1.65 Fuel: RFA-2 SGTP (%): 10 Notes: None Clad Temp (°F)

LICENSING BASIS Analysis of Record PCT 1193 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

1. Errors in Reactor Vessel Lower Plenum Surface Area Calculations 0
2. Discrepancy in Metal Masses Used From Drawings 0
3. Urania-Gadolinia Pellet Thermal Conductivity Calculation 0
4. Pellet Crack and Dish Volume Calculation 0
5. Treatment of Vessel Average Temperature Uncertainty 0
6. Maximum Fuel Rod Time Step Logic 0
7. Radiation Heat Transfer Logic 0
8. NOTRUMP-EM Evaluation of Fuel Pellet Thermal 0 Conductivity Degradation
9. SBLOCTA Cladding Strain Requirement for Fuel 0 Rod Burst
10. Fuel Rod Gap Conductance EiTor 0
11. Radiation Heat Transfer Model Error 0
12. SBLOCTA Pre-DNB Cladding Heat Transfer 0 Coefficient Calculation
13. Insertion of AXIOM' Cladding L TAs 0
14. Vessel Average Temperature Uncertainty 0
15. Error in the Upper Plenum Fluid Volume Calculation 0 B. Planned Plant Modification Evaluations
1. None C. 2018 ECCS Model Assessments
1. U0 2 Fuel Pellet Heat Capacity 0 D. Other
1. None 0 LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 1193 Page 5 of 7

Serial Number 19-246 Docket Nos. 50-336/423 Attachment 2 10 CFR 50.46 MARGIN UTILIZATION - LARGE BREAK LOCA Plant Name: Millstone Power Station, Unit 3 Utility Name: Dominion Energy Nuclear Connecticut, Inc.

Analysis Information EM: ASTRUM (2004) Limiting Break Size: Guillotine Analysis Date: 04/17 /07 Vendor: Westinghouse FQ: 2.6 FdH: 1.65 Fuel: RFA-2 SGTP (%): 10 Notes: None Clad Temp {°F)

LICENSING BASIS Analysis of Record PCT 1781 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

1. HOTSPOT Burst Temperature Logic Errors 0
2. CCFL Global Volume Error 0
3. HOTSPOT Gap Heat Transfer Logic 0
4. Discrepancy in Metal Masses Used From Drawings 0
5. Error in ASTRUM Processing of Average Rod Burnup and Rod Internal Pressure 0
6. Treatment of Vessel Average Temperature Uncertainty 0
7. PBOT and PMID Evaluation 0
8. Evaluation of Fuel Pellet Thermal Conductivity 222 Degradation
9. HOTSPOT Burst Temperature Calculation 0 for ZIRLO Cladding
10. Rod Internal Pressure Calculation 0
11. HOTSPOT Iteration Algorithm for Calculating the 0 Initial Fuel Pellet Average Temperature
12. WCOBRA/TRAC Thermal-Hydraulic History Fil~ 0 Dimension used in HSDRIVER Background
13. WCOBRA/TRAC Automated Restart Process Logic Error 0
14. Initial Fuel Pellet Average Temperature Uncertainty 0 Calculation
15. Elevations for Heat Slab Temperature Initialization 0
16. Heat Transfer Model Error Corrections 0
17. Correction to Heat Transfer Node Initialization 0
18. Mass Conservation Error Fix 0
19. Correction to Split Channel Momentum Equation 0
20. Heat Transfer Logic Correction for Rod Burst Calculation 0
21. Changes to Vessel Superheated Steam Properties 0
22. Update to Metal Density Reference Temperatures 0
23. Decay Heat Model Error Corrections 0
24. Correction to the Pipe Exit Pressure Drop Error 0
25. WCOBRA/TRAC Ul 9 File Dimension Error Correction 0
26. Revised Heat Transfer Multiplier Distributions -91 Page 6 of 7

Serial Number 19-246 Docket Nos. 50-336/423 Attachment 2

27. HOTSPOT Burst Strain Error Correction 21
28. Changes to Grid Blockage Ratio and Porosity 0
29. Grid Heat Transfer Enhancement Calculation 0
30. Burst Elevation Selection 0
31. Errors in Decay Group Uncertainty Factors 0
32. Errors in Support Plate, Core Barrel, and Vessel Wall 0 Unheated Conductor
33. Error in Oxidation Calculations 0
34. Error in use of ASME Steam Tables 0
35. Insertion of AXIOM' Cladding LTAs 0
36. Vessel Average Temperature Uncertainty 0
37. Inconsistent Application of Numerical Ramp Applied 0 to the Entrained Liquid / Vapor Interfacial Drag Coefficient
38. Inappropriate Resetting of Transverse Liquid Mass Flow 0
39. Steady-State Fuel Temperature Calibration Method 0 B. Planned Plant Modification Evaluations
1. None C. 2018 ECCS Model Assessments
1. Vapor Temperature Resetting 0 D. Other
1. None 0 LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 1933 Page 7 of 7

Serial Number 19-246 Docket Nos. 50-338/339 Attachment 3 2018 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 2018 ANNUAL REPORTING OF 10 CFR 50.46 MARGIN UTILIZATION VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION ENERGY VIRGINIA)

NORTH ANNA POWER STATION UNITS 1 AND 2

Serial Number 19-246 Docket Nos. 50-338/339 Attachment 3 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE SMALL BREAK LOCA Plant Name: North Anna Power Station, Unit 1 Utility Name: Virginia Electric and Power Company Analysis Information EM: NOTRUMP Limiting Break Size: 2.75 inches Analysis Date: 12/20/2010 Vendor: Westinghouse FQ: 2.32 F~H: 1.65 Fuel: RFA-2 SGTP (%): 7 Notes: None Clad Temp (°F)

LICENSING BASIS Analysis of Record PCT 1834.1 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

1. NOTRUMP-EM Evaluation of Fuel Pellet Thermal 0 Conductivity Degradation
2. SBLOCA Cladding Strain Requirement for Fuel 0 Rod Burst
3. Fuel Rod Gap Conductance Error 0
4. Radiation Heat Transfer Model Error 0
5. SBLOCTA Pre-DNB Cladding Heat Transfer 0 Coefficient Calculation
6. Error in the Upper Plenum Fluid Volume Calculation 0 B. Planned Plant Modification Evaluations
1. None 0 C. 2018 ECCS Model Assessments
1. U02 Fuel Pellet Heat Capacity 0 D. Other
1. None 0 LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 1834.1 Page 1 of 6

Serial Number 19-246 Docket Nos. 50-338/339 Attachment 3 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE LARGE BREAK LOCA Plant Name: North Anna Power Station, Unit 1 Utility Name: Virginia Electric and Power Company Analysis Information EM: ASTRUM (2004) Limiting Break Size: DEGB Analysis Date: 8/25/2010 Vendor: Westinghouse FQ: 2.32 F~H: 1.65 Fuel: RFA-2 SGTP (%): 7 Notes: Core Power :S I 00% of 2951 MWt; SO Model 54F; l 7x 17 RF A-2 Fuel with ZIRLO or Optimized ZIRLO' cladding, Non-IFBA or IFBA, IFMs Clad Temp (°F)

LICENSING BASIS Analysis of Record PCT 1852 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

1. Evaluation of Fuel Pellet Thermal Conductivity 13 5 Degradation
2. HOTSPOT Burst Temperature Calculation 0 for ZIRLO Cladding
3. Rod Internal Pressure Calculation 0
4. HOTSPOT Iteration Algorithm for Calculating the 0 Initial Fuel Pellet Average Temperature
5. WCOBRA/TRAC Thermal-Hydraulic History File 0 Dimension used in HSDRIVER Background
6. WCOBRA/TRAC Automated Restart Process Logic Error 0
7. Initial Fuel Pellet Average Temperature Uncertainty 1 Calculation
8. Elevations for Heat Slab Temperature Initialization 0
9. Heat Transfer Model Error Corrections 0
10. Correction to Heat Transfer Node Initialization 0
11. Mass Conservation Error Fix 0
12. Correction to Split Channel Momentum Equation 0
13. Heat Transfer Logic Correction for Rod Burst Calculation 0
14. Changes to Vessel Superheated Steam Properties 0
15. Update to Metal Density Reference Temperatures 0
16. Decay Heat Model Error Corrections 0
17. Correction to the Pipe Exit Pressure Drop Error 0
18. WCOBRA/TRAC Ul 9 File Dimension Error Correction . 0
19. Revised Heat Transfer Multiplier Distributions -27
20. HOTSPOT Burst Strain Error Correction 21
21. Changes to Grid Blockage Ratio and Porosity 0
22. Grid Heat Transfer Enhancement Calculation 0
23. Vessel Section 7 Mid-Level Elevation Modeling 0 Page 2 of 6

Serial Number 19-246 Docket Nos. 50-338/339 Attachment 3

24. Burst Elevation Selection 0
25. Errors in Decay Group Uncertainty Factors 0
26. Error in Oxidation Calculations 0
27. Error in use of ASME Steam Tables 0
28. Support Column Core Barrel Unheated Conductor ErrorsO 0
29. Inconsistent Application of Numerical Ramp Applied 0 to the Entrained Liquid / Vapor Interfacial Drag Coefficient
30. Inappropriate Resetting of Transverse Liquid Mass Flow 0
31. Steady-State Fuel Temperature Calibration Method 0
32. Correction to Fuel Pellet TCD Assessment 0 B. Planned Plant Modification Evaluations
1. None 0 C. 2018 ECCS Model Assessments
1. Vapor Temperature Resetting 0 D. Other
1. None LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 1982 Page 3 of 6

Serial Number 19-246 Docket Nos. 50-338/339 Attachment 3 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE SMALL BREAK LOCA Plant Name: North Anna Power Station, Unit 2 Utility Name: Virginia Electric and Power Company Analysis Information EM: NOTRUMP Limiting Break Size: 2.75 inches Analysis Date: 12/20/2010 Vendor: Westinghouse FQ: 2.32 FilH: 1.65 Fuel: RFA-2 SGTP (%): 7 Notes: None Clad Temp (°F)

LICENSING BASIS Analysis of Record PCT 1834.1 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

1. NOTRUMP-EM Evaluation of Fuel Pellet Thermal 0 Conductivity Degradation
2. SBLOCTA Cladding Strain Requirement for Fuel 0 Rod Burst
3. Fuel Rod Gap Conductance Error 0
4. Radiation Heat Transfer Model Error 0
5. SBLOCTA Pre-DNB Cladding Heat Transfer 0 Coefficient Calculation
6. Error in the Upper Plenum Fluid Volume Calculation 0 B. Planned Plant Modification Evaluations
1. None 0 C. 2018 ECCS Model Assessments
1. U02 Fuel Pellet Heat Capacity 0 D. Other
1. None 0 LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 1834.1 Page 4 of 6

Serial Number 19-246 Docket Nos. 50-338/339 Attachment 3 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE LARGE BREAK LOCA Plant Name: North Anna Power Station, Unit 2 Utility Name: Virginia Electric and Power Company Analysis Information EM: ASTRUM (2004) Limiting Break Size: DEGB Analysis Date: 8/25/2010 Vendor: Westinghouse FQ: 2.32 F~H: 1.65 Fuel: RFA-2 SGTP (%): 7 Notes: Core Power :S 100% of2951 MWt; SG Model 54F; 17x17 RFA-2 Fuel with ZIRLO or Optimized ZIRLO' cladding, Non-IFBA or IFBA, IFMs Clad Temp (°F)

LICENSING BASIS Analysis of Record PCT 1852 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

1. Evaluation of Fuel Pellet Thermal Conductivity 135 Degradation 2.. HOTSPOT Burst Temperature Calculation 0 for ZIRLO Cladding
3. Rod Internal Pressure Calculation 0
4. HOTSPOT Iteration Algorithm for Calculating the 0 Initial Fuel Pellet Average Temperature
5. WCOBRA/TRAC Thermal-Hydraulic History File 0 Dimension used in HSDRIVER Background
6. WCOBRA/TRAC Automated Restart Process Logic Error 0
7. Initial Fuel Pellet Average Temperature Uncertainty 1 Calculation
8. Elevations for Heat Slab Temperature Initialization 0
9. Heat Transfer Model Error Corrections 0
10. Correction to Heat Transfer Node Initialization 0
11. Mass Conservation Error Fix 0
12. Correction to Split Channel Momentum Equation 0
13. Heat Transfer Logic Correction for Rod Burst Calculation 0
14. Changes to Vessel Superheated Steam Properties 0
15. Update to Metal Density Reference Temperatures 0
16. Decay Heat Model Error Corrections 0
17. Correction to the Pipe Exit Pressure Drop Error 0
18. WCOBRA/TRAC Ul 9 File Dimension Error Correction 0
19. Revised Heat Transfer Multiplier Distributions -27
20. HOTSPOT Burst Strain Error Correction 21
21. Changes to Grid Blockage Ratio and Porosity 0
22. Grid Heat Transfer Enhancement Calculation 0 Page 5 of 6

Serial Number 19-246 Docket Nos. 50-338/339 Attachment 3

23. Vessel Section 7 Mid-Level Elevation Modeling 0
24. Burst Elevation Selection 0
25. Errors in Decay Group Uncertainty Factors 0
27. Error in Oxidation Calculations 0
28. Error in use of ASME Steam Tables 0
29. Support Column Core Barrel Unheated Conductor Errors 0
30. Inconsistent Application of Numerical Ramp Applied 0 to the Entrained Liquid / Vapor Interfacial Drag Coefficient
31. Inappropriate Resetting of Transverse Liquid Mass Flow 0
32. Steady-State Fuel Temperature Calibration Method 0
33. Correction to Fuel Pellet TCD Assessment 0 B. Planned Plant Modification Evaluations
1. None 0 C. 2018 ECCS Model Assessments
1. Vapor Temperature Resetting 0 D. Other
1. None LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 1982 Page 6 of 6

, Serial Number 19-246 Docket Nos. 50-280/281 Attachment 4 2018 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 2018 ANNUAL REPORTING OF 10 CFR 50.46 MARGIN UTILIZATION VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION ENERGY VIRGINIA)

SURRY POWER STATION UNITS 1 AND 2

Serial Number 19-246 Docket Nos. 50-280/281 Attachment 4 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE SMALL BREAK LOCA Plant Name: Surry Power Station, Unit 1 Utility Name: Virginia Electric and Power Company Analysis Information EM: NOTRUMP Limiting Break Size: 2.75 inches Analysis Date: 5/7/2009 Vendor: Westinghouse FQ: 2.5 F8H: 1.7 Fuel: Upgrade SGTP (%): 7 Notes: None Clad Temp {°F)

LICENSING BASIS Analysis of Record PCT 2012 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

1. Urania-Gadolinia Pellet Thermal Conductivity Calculation. 0
2. Pellet Crack and Dish Volume Calculation. 0
3. Treatment of Vessel Average Temperature Uncertainty 0
4. 15X15 Upgrade Fuel 0
5. Maximum Fuel Rod Time Step Logic 0
6. Radiation Heat Transfer Logic 0
7. NOTRUMP-EM Evaluation of Fuel Pellet Thermal 0 Conductivity Degradation
8. SBLOCTA Cladding Strain Requirement for Fuel 0 Rod Burst
9. Fuel Rod Gap Conductance Error 0
10. Radiation Heat Transfer Model Error 0
11. SBLOCTA Pre-DNB Cladding Heat Transfer 0 Coefficient Calculation
12. Error in the Upper Plenum Fluid Volume Calculation 0 B. Planned Plant Modification Evaluations
1. None 0 C. 2018 ECCS Model Assessments
1. U0 2 Fuel Pellet Heat Capacity 0 D. Other
1. None 0 LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 2012 Page 1 of 6

Serial Number 19-246 Docket Nos. 50-280/281 Attachment 4 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE LARGE BREAK LOCA Plant Name: Surry Power Station, Unit 1 Utility Name: Virginia Electric and Power Company Analysis Information EM: ASTRUM (2004) Limiting Break Size: DEG Analysis Date: 10/6/2010 Vendor: Westinghouse FQ: 2.5 Fi1H: 1.7 Fuel: Upgrade SGTP (%): 7 Notes: None Clad Temp (°F)

LICENSING BASIS Analysis of Record PCT 1853 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

1. Evaluation of Fuel Pellet Thermal Conductivity 183 Degradation
2. Pellet Radial Profile Option -13
3. HOTSPOT Burst Temperature Calculation 0 for ZIRLO Cladding
4. Rod Internal Pressure Calculation 0
5. HOTSPOT Iteration Algorithm for Calculating the 0 Initial Fuel Pellet Average Temperature
6. WCOBRA/TRAC Thermal-Hydraulic History File 0 Dimension used in HSDRIVER Background
7. WCOBRA/TRAC Automated Restart Process Logic Error 0
8. Initial Fuel Pellet Average Temperature Uncertainty 0 Calculation
9. Elevations for Heat Slab Temperature Initialization 0
10. Heat Transfer Model Error Corrections 0
11. Correction to Heat Transfer Node Initialization 0
12. Mass Conservation Error Fix 0
13. Correction to Split Channel Momentum Equation 0
14. Heat Transfer Logic Correction for Rod Burst Calculation 0
15. Changes to Vessel Superheated Steam Properties 0
16. Update to Metal Density Reference Temperatures 0
17. Decay Heat Model Error Corrections 0
18. Correction to the Pipe Exit Pressure Drop Error 0
19. WCOBRA/TRAC Ul 9 File Dimension Error Correction 0
20. Revised Heat Transfer Multiplier Distributions -7
21. HOTSPOT Burst Strain Error Correction 51
22. Changes to Grid Blockage Ratio and Porosity 0
23. Grid Heat Transfer Enhancement Calculation 0
24. Vessel Section 7 Mid-Level Elevation Modeling 0 Page 2 of 6

Serial Number 19-246 Docket Nos. 50-280/281 Attachment 4

25. Burst Elevation Selection 0
26. Errors in Decay Group Uncertainty Factors 4
27. Evaluation of Additional Containment Metal 0
28. Error in Oxidation Calculations 0
29. Error in use of ASME Steam Tables 0
30. Core Barrel Unheated Conductor Errors 0
31. Discrepancy in Wetted Perimeter Inputs 0
32. Inconsistent Application of Numerical Ramp Applied 0 to the Entrained Liquid / Vapor Interfacial Drag Coefficient
33. Inappropriate Resetting of Transverse Liquid Mass Flow 0
34. Steady-State Fuel Temperature Calibration Method 0 B. Planned Plant Modification Evaluations
1. None 0 C. 2018 ECCS Model Assessments
1. Vapor Temperature Resetting 0 D. Other
1. None 0 LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 2071 Page 3 of 6

Serial Number 19-246 Docket Nos. 50-280/281 Attachment 4 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE SMALL BREAK LOCA Plant Name: Surry Power Station, Unit 2 Utility Name: Virginia Electric and Power Company Analysis Information EM: NOTRUMP Limiting Break Size: 2.75 inches Analysis Date: 5/7/2009 Vendor: Westinghouse FQ: 2.5 F~H: 1.7 Fuel: Upgrade SGTP (%): 7 Notes: None Clad Temp (°F)

LICENSING BASIS Analysis of Record PCT 2012 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

1. Urania-Gadolinia Pellet Thermal Conductivity Calculation. 0
2. Pellet Crack and Dish Volume Calculation. 0
3. Treatment of Vessel Average Temperature Uncertainty 0
4. 15Xl 5 Upgrade Fuel 0
5. Maximum Fuel Rod Time Step Logic 0
6. Radiation Heat Transfer Logic 0
7. NOTRUMP-EM Evaluation of Fuel Pellet Thermal 0 Conductivity Degradation
8. SBLOCTA Cladding Strain Requirement for Fuel 0 Rod Burst
9. Fuel Rod Gap Conductance Error 0
10. Radiation Heat Transfer Model Error 0
11. SBLOCTA Pre-DNB Cladding Heat Transfer 0 Coefficient Calculation
12. Error in the Upper Plenum Fluid Volume Calculation 0 B. Planned Plant Modification Evaluations
1. None 0 C. 2018 ECCS Model Assessments
1. U02 Fuel Pellet Heat Capacity 0 D. Other
1. None 0 LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 2012 Page 4 of 6

I Serial Number 19-246 Docket Nos. 50-280/281 Attachment 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: ASTRUM (2004) Limiting Break Size: DEG Analysis Date: 10/6/2010 Vendor: Westinghouse FQ: 2.5 FilH: 1.7 Fuel: Upgrade SGTP (%): 7 Notes: None Clad Temp (°F)

LICENSING BASIS Analysis of Record PCT 1853 PCT ASSESSMENTS (Delta PCT)

A. Prior ECCS Model Assessments

1. Evaluation of Fuel Pellet Thermal Conductivity 183 Degradation
2. Pellet Radial Profile Option -13
3. HOTSPOT Burst Temperature Calculation 0 for ZIRLO Cladding
4. Rod Internal Pressure Calculation 0
5. HOTSPOT Iteration Algorithm for Calculating the 0 Initial Fuel Pellet Average Temperature
6. WCOBRA/TRAC Thermal-Hydraulic History File 0 Dimension used in HSDRIVER Background
7. WCOBRA/TRAC Automated Restart Process Logic Error 0
8. Initial Fuel Pellet Average Temperature Uncertainty 0 Calculation
9. Elevations for Heat Slab Temperature Initialization 0
10. Heat Transfer Model Error Corrections 0
11. Correction to Heat Transfer Node Initialization 0
12. Mass Conservation Error Fix 0
13. Correction to Split Channel Momentum Equation 0
14. Heat Transfer Logic Correction for Rod Burst Calculation 0
15. Changes to Vessel Superheated Steam Properties 0
16. Update to Metal Density Reference Temperatures 0
17. Decay Heat Model Error Corrections 0
18. Correction to the Pipe Exit Pressure Drop Error 0
19. WCOBRA/TRAC U19 File Dimension Error Correction 0
20. Revised Heat Transfer Multiplier Distributions -7
21. HOTSPOT Burst Strain Error Correction 51
22. Changes to Grid Blockage Ratio and Porosity 0
23. Grid Heat Transfer Enhancement Calculation 0 Page 5 of 6

Serial Number 19-246 Docket Nos. 50-280/281 Attachment 4

24. Vessel Section 7 Mid-Level Elevation Modeling 0
25. Burst Elevation Selection 0
26. Errors in Decay Group Uncertainty Factors 4
27. Evaluation of Additional Containment Metal 0
28. En-or in Oxidation Calculations 0
29. Error in use of ASME Steam Tables 0
30. Core Barrel Unheated Conductor En-ors 0
31. Discrepancy in Wetted Perimeter Inputs 0
32. Inconsistent Application of Numerical Ramp Applied 0 to the Entrained Liquid / Vapor Interfacial Drag Coefficient
33. Inappropriate Res~tting of Transverse Liquid Mass Flow 0
34. Steady-State Fuel Temperature Calibration Method 0 B. Planned Plant Modification Evaluations
1. None 0 C. 2018 ECCS Model Assessments
1. Vapor Temperature Resetting 0 D. Other
1. None 0 LICENSING BASIS PCT+ PCT ASSESSMENTS PCT= 2071 Page 6 of 6
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