ML13183A068
| ML13183A068 | |
| Person / Time | |
|---|---|
| Site: | Millstone, Kewaunee, Surry, North Anna  |
| Issue date: | 06/26/2013 |
| From: | Heacock D Dominion, Dominion Energy Kewaunee, Dominion Nuclear Connecticut, Dominion Resources, Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 13-361 | |
| Download: ML13183A068 (43) | |
Text
Dominion Resources Services, Inc. urnhU...lh:
lnnsbrook Technical Center i~p Dominion 5000 Dominion Boulevard, 2SE, Glen Allen, VA 23060 June 26, 2013 U.S. Nuclear Regulatory Commission Serial No.13-361 Attention: Document Control Desk NL&OS/ETS R2 Washington, DC 20555 Docket Nos. 50-305 50-336/423 50-338/339 50-280/281 License Nos. DPR-43 DPR-65/NPF-49 NPF-4/7 DPR-32/37 DOMINION ENERGY KEWAUNEE, INC.
DOMINION NUCLEAR CONNECTICUT, INC.
VIRGINIA ELECTRIC AND POWER COMPANY KEWAUNEE POWER STATION MILLSTONE POWER STATION UNITS 2 AND 3 NORTH ANNA POWER STATION UNITS I AND 2 SURRY POWER STATION UNITS I AND 2 2012 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 Kewaunee, Inc. (DEK),
Dominion Nuclear Connecticut, Inc. (DNC), and Virginia Electric and Power Company (Dominion) hereby submit the annual summary of permanent changes to the emergency core cooling system (ECCS) evaluation models for Kewaunee Power Station (KPS),
Millstone Power Station Unit 2 (MPS2) and Unit 3 (MPS3), North Anna Power Station Unit 1 (NAPS1) and Unit 2 (NAPS2), and Surry Power Station Unit 1 (SPS1) and Unit 2 (SPS2), respectively. of this letter provides a report describing plant-specific evaluation model changes associated with the Westinghouse and AREVA Small Break Loss of Coolant Accident (SBLOCA) and Large Break Loss of Coolant Accident (LBLOCA) ECCS evaluation models for KPS, MPS2 and MPS3, NAPS1 and NAPS2, and SPS1 and SPS2.
Specific information regarding the effect of the ECCS evaluation model changes upon the reported SBLOCA and LBLOCA analyses of record results for KPS, MPS2 and MPS3, NAPS1 and NAPS2, and SPS1 and SPS2 is provided in Attachments 2, 3, 4 and 5, respectively. The calculated peak cladding temperatures (PCT) for the SBLOCA and LBLOCA analyses for KPS, MPS2 and MPS3, NAPS1 and NAPS2, and SPS1 and SPS2 are summarized below.
Kewaunee - Small break - Westinghouse Evaluation Model: 1065 0 F Kewaunee - Large break - Westinghouse Evaluation Model: 1980°F Millstone Unit 2 - Small break - AREVA Evaluation Model: 1801 OF Millstone Unit 2 - Large break - AREVA Evaluation Model: 1845 0 F Millstone Unit 3 - Small break - Westinghouse Evaluation Model: 1193 0 F C)24
Serial Number 13-361 Docket Nos. 50-3051336/4231338/339/280/281 Page 2 of 4 Millstone Unit 3 - Large break - Westinghouse Evaluation Model: 2003°F North Anna Unit 1 - Small break - AREVA Evaluation Model: 1395 0 F North Anna Unit 1 - Large break - AREVA Evaluation Model: 1876 0 F North Anna Unit 2 - Small break - AREVA Evaluation Model: 1338 0 F North Anna Unit 2 - Large break - AREVA Evaluation Model: 1919°F North Anna Unit 1 - Small break - Westinghouse Evaluation Model: 1834.1 0 F North Anna Unit 1 - Large break - Westinghouse Evaluation Model: 1987 0 F North Anna Unit 2 - Small break - Westinghouse Evaluation Model: 1834.1 0 F North Anna Unit 2 - Large break - Westinghouse Evaluation Model: 1972 0 F Surry Units 1 and 2 - Small break - Westinghouse Evaluation Model: 2012°F Surry Units 1 and 2 - Large break - Westinghouse Evaluation Model: 2037°F The LOCA results for KPS, MPS2 and MPS3, NAPS1 and NAPS2, and SPS1 and SPS2 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.
This information satisfies the 2012 annual reporting requirements of 10 CFR 50.46(a)(3)(ii).
If you have any questions regarding this submittal, please contact Mr. Thomas Shaub at (804) 273-2763.
Respectfully, David A. Heacock President and Chief Nuclear Officer Dominion Energy Kewaunee, Inc.
Dominion Nuclear Connecticut, Inc.
Virginia Electric and Power Company Commitments made in this letter: None Attachments:
- 1. Report of Changes in Westinghouse and AREVA ECCS Evaluation Models
- 2. 2012 Annual Reporting of 10 CFR 50.46 Margin Utilization - Kewaunee Power Station
- 3. 2012 Annual Reporting of 10 CFR 50.46 Margin Utilization - Millstone Power Station Units 2 and 3
- 4. 2012 Annual Reporting of 10 CFR 50.46 Margin Utilization - North Anna Power Station Units 1 and 2
- 5. 2012 Annual Reporting of 10 CFR 50.46 Margin Utilization - Surry Power Station Units 1 and 2
Serial Number 13-361 Docket Nos. 50-305/3361423/338/339/280/281 Page 3 of 4 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 U. S. Nuclear Regulatory Commission, Region III Regional Administrator 2443 Warrenville Road Suite 210 Lisle, Illinois 60532-4352 NRC Senior Resident Inspector Kewaunee Power Station NRC Senior Resident Inspector Millstone Power Station NRC Senior Resident Inspector North Anna Power Station NRC Senior Resident Inspector Surry Power Station Mr. K. D. Feintuch NRC Project Manager Kewaunee U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 H-4A 11555 Rockville Pike Rockville, MD 20852-2738 Dr. V. Sreenivas NRC Project Manager North Anna U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G-9A 11555 Rockville Pike Rockville, MD 20852-2738
4 Serial Number 13-361 Docket Nos. 50-305/336/423/338/3391280/281 Page 4 of 4 Ms. N. S. Morgan NRC Project Manager Millstone Units 2 and 3 U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 C-2A 11555 Rockville Pike Rockville, MD 20852-2738 Ms. K. R. Cotton Gross NRC Project Manager Surry U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G-9A 11555 Rockville Pike Rockville, MD 20852-2738 Mr. J. E. Reasor, Jr.
Old Dominion Electric Cooperative Innsbrook Corporate Center, Suite 300 4201 Dominion Blvd.
Glen Allen, Virginia 23060
Serial Number 13-361 Docket Nos. 50-305/3361423/338/3391280/281 ATTACHMENT 1 2012 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 REPORT OF CHANGES IN WESTINGHOUSE AND AREVA ECCS EVALUATION MODELS DOMINION ENERGY KEWAUNEE, INC.
DOMINION NUCLEAR CONNECTICUT, INC.
VIRGINIA ELECTRIC AND POWER COMPANY KEWAUNEE POWER STATION MILLSTONE POWER STATION UNITS 2 AND 3 NORTH ANNA POWER STATION UNITS 1 AND 2 SURRY POWER STATION UNITS I AND 2
Serial Number 13-361 Docket Nos. 50-305/3361423/338/339/280/281 Attachment 1, Page 1 of 12 REPORT OF CHANGES IN WESTINGHOUSE AND AREVA ECCS EVALUATION MODELS Kewaunee Power Station (KPS)
- 1. Westinghouse identified the following change and error affecting the 1985 Westinghouse Small Break Loss of Coolant Accident (SBLOCA) Evaluation Model (EM) with NOTRUMP for KPS.
NOTRUMP-EM Evaluation of Fuel Pellet Thermal Conductivity Degradation.
An evaluation has been completed to estimate the effect of fuel pellet thermal conductivity degradation (TCD) on peak cladding temperature (PCT) for plants in the United States with analyses using the 1985 Westinghouse SBLOCA EM with NOTRUMP (NOTRUMP-EM). Based on the phenomena and physics of the SBLOCA transient, in combination with limited sensitivity calculations, it is concluded that TCD has a negligible effect on the limiting cladding temperature transient, leading to an estimated PCT impact of 0°F.
- 2. Westinghouse identified the following changes and errors applicable to the KPS 1999 Westinghouse Best Estimate (BE) Large Break Loss of Coolant Accident (LBLOCA) EM with application to Pressurized Water Reactors (PWRs) with upper plenum injection.
" General Code Maintenance. Various changes have been made to enhance the usability of the codes and to help preclude errors in analyses. This includes items such as modifying input variable definitions, units, and defaults; improving the input diagnostic checks; enhancing the code output; optimizing active coding; and eliminating inactive coding. The nature of these changes leads to an estimated PCT impact of 0°F.
" HOTSPOT Burst Temperature Calculation for ZIRLO Cladding. A problem was identified in the calculation of the burst temperature for ZIRLO cladding in the HOTSPOT code when the cladding engineering hoop stress exceeds 15,622 psi. This problem results in either program failure or an invalid extrapolation of the burst temperature vs. engineering hoop stress table. This problem has been evaluated for impact on existing analyses. The evaluation of existing analyses demonstrated no impact on the overall PCT results, leading to an estimated effect of 0°F.
" Rod Internal Pressure Calculation. Several issues which affect the calculation of rod internal pressure (RIP) have been identified for certain BE LBLOCA EMs. These issues include the sampling of RIP uncertainties, updating HOTSPOT to consider the effect of transient RIP variations in the application of the uncertainty, and generating RIPs at a consistent rod power.
These issues have been evaluated to estimate the impact on existing LBLOCA analysis results. The resolution of these issues represents a closely-related group of changes. The effects described above are either
Serial Number 13-361 Docket Nos. 50-305/3361423/338/339/2801281 Attachment 1, Page 2 of 12 judged to have a negligible effect on existing LBLOCA analysis results or have been adequately incorporated into the thermal conductivity degradation evaluations, leading to an estimated PCT impact of 0°F.
HOTSPOT Iteration Algorithm for Calculating the Initial Fuel Pellet Average Temperature. The HOTSPOT code has been updated to incorporate the following corrections to the iteration algorithm for calculating the initial fuel pellet average temperature: (1) bypass the iteration when the input value satisfies the acceptance criterion, (2) prevent low-end extrapolation of the gap heat transfer coefficient, (3) prevent premature termination of the iteration that occurred under certain conditions, and (4) prevent further adjustment of the gap heat transfer coefficient after reaching the iteration limit. These changes represent a closely-related group of changes. Sample calculations and engineering judgment lead to an estimated PCT impact of 0°F.
WCOBRA/TRAC Thermal-Hydraulic History File Dimension Used in HSDRIVER. A problem was identified in the dimension of the WCOBRAITRAC thermal-hydraulic history file used in HSDRIVER. The array that is used to store the information from the WCOBRA/TRAC thermal-hydraulic history file is dimensioned to 3000 in HSDRIVER. It is possible for this file to contain more than 3000 curves. If that is the case, it is possible that the curves would not be used correctly in the downstream HOTSPOT execution. An extent-of-condition review indicated that resolution of this issue does not impact the PCT calculation for prior LBLOCA analyses.
Resolution of this issue does not impact the PCT calculation for prior LBLOCA analyses, which leads to a PCT impact of 0°F.
Evaluation of Fuel Pellet Thermal Conductivity Degradation. Fuel pellet TCD and peaking factor burndown were not explicitly considered in the LBLOCA Analysis of Record (AOR) for Kewaunee. Nuclear Regulatory Commission (NRC) Information Notice 2011-21 notified addressees of recent information obtained concerning the impact of irradiation on fuel thermal conductivity and its potential to cause significantly higher predicted PCT results in realistic ECCS EMs. The NRC requested Dominion to provide an estimated effect of TCD on the PCT calculation for the ECCS at Kewaunee. A quantitative evaluation was performed to assess the PCT effect of TCD and peaking factor burndown with other considerations of burnup on the LBLOCA analysis for Kewaunee, and concluded that the estimated PCT impact was 50°F for 10 CFR 50.46 reporting purposes.
For Kewaunee, this issue resulted in the accumulation of changes to the calculated peak fuel cladding temperature to exceed 50°F and was previously reported to the NRC in a letter dated March 15, 2012 (Serial No.12-100) to meet the 30-day reporting requirements of 10 CFR 50.46(a)(3)(ii).
Serial Number 13-361 Docket Nos. 50-305/336/42313381339/280/281 Attachment 1, Page 3 of 12 Evaluation of Design Input Changes with Respect to Plant Operation. To demonstrate compliance with the 10 CFR 50.46(b)(1) acceptance criterion concerning PCT when explicitly considering fuel pellet TCD and peaking factor burndown in the LBLOCA AOR for Kewaunee, design input values were revised to more closely represent current plant operation. These input changes do not constitute changes to the approved 1999 Westinghouse BE LBLOCA EM, Application to PWRs with Upper Plenum Injection. The updated inputs for Kewaunee include:
- Reduction in full-power FDH (hot rod average power) to current COLR limit.
> Corresponding reduction in hot assembly average power.
Dominion and its vendor, Westinghouse Electric Company LLC, utilize processes which ensure that LOCA analysis input values conservatively bound the as-operated plant values for those parameters. A quantitative evaluation was performed to estimate an overall PCT change due to changes in design input parameters. The evaluation concluded that the estimated PCT impact of these analysis input changes was -1 15'F for 10 CFR 50.46 reporting purposes.
For Kewaunee, this issue resulted in the accumulation of changes to the calculated peak fuel cladding temperature to exceed 50'F and was previously reported to the NRC in a letter dated March 15, 2012 (Serial No.12-100) to meet the 30-day reporting requirements of 10 CFR 50.46(a)(3)(ii).
WCOBRA/TRAC Automated Restart Process Logic Error. A minor error was identified in the WCOBRA/TRAC Automated Restart Process (WARP) logic for defining the Double-Ended Guillotine (DEG) break tables. The error has been evaluated for impact on current licensing-basis analysis results and will be incorporated into the plant-specific analyses on a forward-fit basis. This error was evaluated to have a negligible impact on the LBLOCA analysis results, leading to an estimated PCT impact of 0°F.
Millstone Power Station Unit 2 (MPS2)
Serial Number 13-361 Docket Nos. 50-305/3361423/338/3391280/281 Attachment 1, Page 4 of 12 Millstone Power Station Unit 3 (MPS3)
- 1. Westinghouse identified the following changes and errors to the 1985 Westinghouse SBLOCA EM with NOTRUMP.
NOTRUMP-EM Evaluation of Fuel Pellet Thermal Conductivity Degradation.
An evaluation has been completed to estimate the effect of fuel pellet TCD on PCT for plants in the United States with analyses using the 1985 Westinghouse SBLOCA NOTRUMP-EM. Based on the phenomena and physics of the SBLOCA transient, in combination with limited sensitivity calculations, it is concluded that TCD has a negligible effect on the limiting cladding temperature transient, leading to an estimated PCT impact of 00F.
- 2. Westinghouse identified the following changes and errors applicable to the 2004 Westinghouse BE LBLOCA EM using the Automated Statistical Treatment of Uncertainty Method (ASTRUM) for MPS3.
" General Code Maintenance. Various changes have been made to enhance the usability of codes and to streamline future analyses. Examples of these changes include modifying input variable definitions, units and defaults; improving the input diagnostic checks; enhancing the code output; optimizing active coding; and eliminating inactive coding. The nature of these changes leads to an estimated PCT impact of 0°F.
" HOTSPOT Burst Temperature Calculation for ZIRLO Cladding. A problem was identified in the calculation of the burst temperature for ZIRLO cladding in the HOTSPOT code when the cladding engineering hoop stress exceeds 15,622 psi. This problem results in either program failure or an invalid extrapolation of the burst temperature vs. engineering hoop stress table. This problem has been evaluated for impact on existing analyses. The evaluation of existing analyses demonstrated no impact on the overall PCT results, leading to an estimated effect of 0°F.
- Rod Internal Pressure Calculation. Several issues which affect the calculation of RIP have been identified for certain BE LBLOCA EMs. These issues include the sampling of RIP uncertainties, updating HOTSPOT to consider the effect of transient RIP variations in the application of the uncertainty, and generating RIPs at a consistent rod power. These issues have been evaluated to estimate the impact on existing LBLOCA analysis results. The resolution of these issues represents a closely-related group of changes. The effects described above are either judged to have a negligible effect on existing LBLOCA analysis results or have been adequately incorporated into the thermal conductivity degradation evaluations, leading to an estimated PCT impact of 0°F.
- HOTSPOT Iteration Algorithm for Calculating the Initial Fuel Pellet Average Temperature. The HOTSPOT code has been updated to incorporate the
Serial Number 13-361 Docket Nos. 50-305/336/423/338/339/280/281 Attachment 1, Page 5 of 12 following corrections to the iteration algorithm for calculating the initial fuel pellet average temperature: (1) bypass the iteration when the input value satisfies the acceptance criterion, (2) prevent low-end extrapolation of the gap heat transfer coefficient, (3) prevent premature termination of the iteration that occurred under certain conditions, and (4) prevent further adjustment of the gap heat transfer coefficient after reaching the iteration limit. These changes represent a closely-related group of changes. Sample calculations and engineering judgment lead to an estimated PCT impact of 0°F.
WCOBRA/TRAC Thermal-Hydraulic History File Dimension Used in HSDRIVER. A problem was identified in the dimension of the WCOBRA/TRAC thermal-hydraulic history file used in HSDRIVER. The array that is used to store the information from the WCOBRA/TRAC thermal-hydraulic history file is dimensioned to 3000 in HSDRIVER. It is possible for this file to contain more than 3000 curves. If that is the case, it is possible that the curves would not be used correctly in the downstream HOTSPOT execution. An extent-of-condition review indicated that resolution of this issue does not impact the PCT calculation for prior LBLOCA analyses.
Resolution of this issue does not impact the PCT calculation for prior LBLOCA analyses, which leads to a PCT impact of 0 0F.
WCOBRA/TRAC Automated Restart Process Logic Error. A minor error was identified in the WARP logic for defining the DEG break tables. The error has been evaluated for impact on current licensing-basis analysis results and will be incorporated into the plant-specific analyses on a forward-fit basis. This error was evaluated to have a negligible impact on the Large Break LOCA analysis results, leading to an estimated PCT impact of 00 F.
Evaluation of Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown. Fuel pellet TCD and peaking factor burndown were not explicitly considered in the MPS3 BE LBLOCA AOR. NRC Information Notice 2011-21 notified addressees of recent information obtained concerning the impact of irradiation on fuel thermal conductivity and its potential to cause significantly higher predicted PCT results in realistic ECCS EMs. This evaluation provides an estimated effect of fuel pellet TCD and peaking factor burndown on the PCT calculation for the Millstone Unit 3 BE LBLOCA AOR.
A quantitative evaluation was performed to assess the PCT effect of fuel pellet TCD and peaking factor burndown on the MPS3 BE LBLOCA analysis and concluded that the estimated PCT impact was 222°F for 10 CFR 50.46 reporting purposes.
For MPS3, this issue resulted in the accumulation of changes to the calculated peak fuel cladding temperature to exceed 50'F, and was previously reported to the NRC in a letter dated November 29, 2012 (Serial
Serial Number 13-361 Docket Nos. 50-305/3361423/338/339/280/281 Attachment 1, Page 6 of 12 No.12-705) to meet the 30-day reporting requirements of 10 CFR 50.46(a)(3)(ii).
North Anna Power Station Units 1 and 2 (NAPS1 and NAPS2)
- 2. AREVA identified the following changes and errors applicable to the Realistic LBLOCA (RLBLOCA), RELAP5 based EM for NAPS1 and NAPS2.
Cathcart-Pawel Uncertainty Implementation in RLBLOCA Applications. In RLBLOCA analyses, energy released through the oxidation of cladding is calculated from the Cathcart-Pawel correlation for oxide growth. RLBLOCA applications implement the Cathcart-Pawel uncertainty using a log-normal function for the uncertainty multiplier applied to a constant. The equation to determine the uncertainty multiplier was determined to be incorrect.
However, the incorrect equation still has a log-normal distribution like the corrected equation for the uncertainty multiplier. In addition, the range of sampled values for the uncertainty multiplier falls within the range expected for the corrected equation for the uncertainty multiplier, B. The estimated impact of this change on the LBLOCA analyses for the NAPS1 and NAPS2 analyses is +0°F on the calculated PCT.
" Liquid Fallback into Surrounding Six Assemblies. The limiting case revealed non-conservatism in the core exit modeling relative to the form loss coefficient (FLC) between the upper plenum and the central core region.
Liquid communication from the central core region, which represents six assemblies surrounding the hot channel, to the hot channel resulted in steam cooling and a reduction in the hot rod PCT at elevations associated with the peaked axial power.
This is related to a previous issue in which it was discovered that the RLBLOCA reactor vessel model, in particular the upper plenum, was producing a non-physical phenomenon. This non-physical phenomenon was manifesting itself by producing an influx of liquid from the upper plenum into the hot assembly. The previous 50.46 evaluation identified the cases with liquid fallback in the hot assembly and reran these cases with a modification to the reverse FLC for the hot assembly and central core. The selection of the cases to be evaluated was made by verifying the occurrence of liquid fallback at the hot assembly exit junction. For each case evaluated, further investigation was deemed necessary if liquid fallback at the hot assembly junction was detected to have occurred subsequent to the beginning of the core reflood. For cases where larger amounts of liquid fallback were
Serial Number 13-361 Docket Nos. 50-305/3361423/338/339/280/281 Attachment 1, Page 7 of 12 detected and the case had the potential of becoming limiting, the selection was made without regard to the timing of the liquid fallback.
The issue has now expanded to the area of concern for liquid fallback from the hot assembly to include the surrounding six assemblies. Additional cases were identified that had liquid downflow into the central core and these were rerun with the high reverse FLC for the hot assembly and central core region.
It was discovered in the calculation supporting this issue that the results for the previous issue were incorrect. This is due to incorrectly applying a high reverse FLC to the average core. The current evaluation appropriately applied the correction to the hot assembly and the central core region.
Upon further evaluation of the reverse FLC being applied only to the hot assembly and central core region, the estimated PCT impact for NAPS1 was -8°F and for NAPS2 was +31'F.
- 3. Westinghouse identified the following change or error in the SBLOCA EMs for NAPS1 and NAPS2. It is noted that, while the Westinghouse analyses for both NAPS1 and NAPS2 were impacted during 2012, only NAPS1 operated with Westinghouse fuel during 2012.
NOTRUMP-EM Evaluation of Fuel Pellet Thermal Conductivity Degradation.
An evaluation has been completed to estimate the effect of fuel pellet TCD on PCT for plants in the United States with analyses using the 1985 Westinghouse Small Break LOCA NOTRUMP-EM. Based on the phenomena and physics of the SBLOCA transient, in combination with limited sensitivity calculations, it is concluded that TCD has a negligible effect on the limiting cladding temperature transient, leading to an estimated PCT impact of 0°F.
- 4. Westinghouse identified the following changes and errors applicable to the 2004 Westinghouse BE LOCA EM using the ASTRUM based EMs for NAPSI and NAPS2. It is noted that, while the Westinghouse analyses for both NAPSI and NAPS2 were impacted during 2012, only NAPSI operated with Westinghouse fuel during 2012.
General Code Maintenance. Various changes have been made to enhance the usability of codes and to streamline future analyses. Examples of these changes include modifying input variable definitions, units and defaults; improving the input diagnostic checks; enhancing the code output; optimizing active coding; and eliminating inactive coding. The nature of these changes leads to an estimated PCT impact of 0°F.
HOTSPOT Burst Temperature Calculation for ZIRLO Cladding. A problem was identified in the calculation of the burst temperature for ZIRLO cladding in the HOTSPOT code when the cladding engineering hoop stress exceeds 15,622 psi. This problem results in either program failure or an invalid
Serial Number 13-361 Docket Nos. 50-305/336/423/338/339/280/281 Attachment 1, Page 8 of 12 extrapolation of the burst temperature vs. engineering hoop stress table. This problem has been evaluated for impact on existing analyses. The evaluation of existing analyses demonstrated no impact on the overall PCT results, leading to an estimated effect of 0°F.
Rod Internal Pressure Calculation. Several issues which affect the calculation of RIP have been identified for certain BE LBLOCA EMs. These issues include the sampling of RIP uncertainties, updating HOTSPOT to consider the effect of transient RIP variations in the application of the uncertainty, and generating RIPs at a consistent rod power. These issues have been evaluated to estimate the impact on existing LBLOCA analysis results. The resolution of these issues represents a closely-related group of changes. The effects described above are either judged to have a negligible effect on existing LBLOCA analysis results or have been adequately incorporated into the thermal conductivity degradation evaluations, leading to an estimated PCT impact of 00F.
HOTSPOT Iteration Algorithm for Calculating the Initial Fuel Pellet Average Temperature. The HOTSPOT code has been updated to incorporate the following corrections to the iteration algorithm for calculating the initial fuel pellet average temperature: (1) bypass the iteration when the input value satisfies the acceptance criterion, (2) prevent low-end extrapolation of the gap heat transfer coefficient, (3) prevent premature termination of the iteration that occurred under certain conditions, and (4) prevent further adjustment of the gap heat transfer coefficient after reaching the iteration limit. These changes represent a closely-related group of changes. Sample calculations and engineering judgment lead to an estimated PCT impact of 0°F.
WCOBRA/TRAC Thermal-Hydraulic History File Dimension Used in HSDRIVER. A problem was identified in the dimension of the WCOBRA/TRAC thermal-hydraulic history file used in HSDRIVER. The array that is used to store the information from the WCOBRA/TRAC thermal-hydraulic history file is dimensioned to 3000 in HSDRIVER. It is possible for this file to contain more than 3000 curves. If that is the case, it is possible that the curves would not be used correctly in the downstream HOTSPOT execution. An extent-of-condition review indicated that resolution of this issue does not impact the PCT calculation for prior LBLOCA analyses.
Resolution of this issue does not impact the PCT calculation for prior LBLOCA analyses, which leads to a PCT impact of 0°F.
WCOBRA/TRAC Automated Restart Process Logic Error. A minor error was identified in the WARP logic for defining the DEG break tables. The error has been evaluated for impact on current licensing-basis analysis results and will be incorporated into the plant-specific analyses on a forward-fit basis. This
Serial Number 13-361 Docket Nos. 50-305/3361423/338/339/280/281 Attachment 1, Page 9 of 12 error was evaluated to have a negligible impact on the LBLOCA analysis results, leading to an estimated PCT impact of 0°F.
Evaluation of Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown. Fuel pellet thermal TCD and peaking factor burndown were not explicitly considered in the North Anna BE LBLOCA AOR. NRC Information Notice 2011-21 notified addressees of recent information obtained concerning the impact of irradiation on fuel thermal conductivity and its potential to cause significantly higher predicted PCT results in realistic ECCS EMs. This evaluation provides an estimated effect of fuel pellet TCD and peaking factor burndown on the PCT calculation for the North Anna BE LBLOCA AOR. A quantitative evaluation was performed to assess the PCT effect of fuel pellet TCD and peaking factor burndown on the North Anna Unit 1 BE LBLOCA analysis and concluded that the estimated PCT impact was 135°F for 10 CFR 50.46 reporting purposes. For North Anna Unit 2 the estimated PCT impact was 101°F for 10 CFR 50.46 reporting purposes.
For North Anna this issue resulted in the accumulation of changes to the calculated peak fuel cladding temperature to exceed 50°F and was previously reported to the NRC in a letter dated May 16, 2012 (Serial No.12-330) to meet the 30-day reporting requirements of 10 CFR 50.46(a)(3)(ii).
Surry Power Station Units 1 and 2 (SPS1 and SPS2)
- 1. Westinghouse identified the following changes and errors applicable to the 1985 Westinghouse SBLOCA EM with NOTRUMP for SPS.
NOTRUMP-EM Evaluation of Fuel Pellet Thermal Conductivity Degradation.
An evaluation has been completed to estimate the effect of fuel pellet TCD on PCT for plants in the United States with analyses using the 1985 Westinghouse SBLOCA NOTRUMP-EM. Based on the phenomena and physics of the SBLOCA transient, in combination with limited sensitivity calculations, it is concluded that TCD has a negligible effect on the limiting cladding temperature transient, leading to an estimated PCT impact of 0°F.
- 2. Westinghouse identified the following changes and errors applicable to the 2004 Westinghouse BE LBLOCA EM using the ASTRUM for SPS1 and SPS2.
General Code Maintenance. Various changes have been made to enhance the usability of codes and to streamline future analyses. Examples of these changes include modifying input variable definitions, units and defaults; improving the input diagnostic checks; enhancing the code output; optimizing active coding; and eliminating inactive coding. The nature of these changes leads to an estimated PCT impact of 0°F.
Serial Number 13-361 Docket Nos. 50-305/33614231338/339/280/281 Attachment 1, Page 10 of 12 HOTSPOT Burst Temperature Calculation for ZIRLO Cladding. A problem was identified in the calculation of the burst temperature for ZIRLO cladding in the HOTSPOT code when the cladding engineering hoop stress exceeds 15,622 psi. This problem results in either program failure or an invalid extrapolation of the burst temperature vs. engineering hoop stress table. This problem has been evaluated for impact on existing analyses. The evaluation of existing analyses demonstrated no impact on the overall PCT results, leading to an estimated effect of 0°F.
Rod Internal Pressure Calculation. Several issues which affect the calculation of RIP have been identified for certain BE LBLOCA EMs. These issues include the sampling of RIP uncertainties, updating HOTSPOT to consider the effect of transient RIP variations in the application of the uncertainty, and generating RIPs at a consistent rod power. These issues have been evaluated to estimate the impact on existing LBLOCA analysis results. The resolution of these issues represents a closely-related group of changes. The effects described above are either judged to have a negligible effect on existing LBLOCA analysis results or have been adequately incorporated into the thermal conductivity degradation evaluations, leading to an estimated PCT impact of 0°F.
HOTSPOT Iteration Algorithm for Calculating the Initial Fuel Pellet Average Temperature. The HOTSPOT code has been updated to incorporate the following corrections to the iteration algorithm for calculating the initial fuel pellet average temperature: (1) bypass the iteration when the input value satisfies the acceptance criterion, (2) prevent low-end extrapolation of the gap heat transfer coefficient, (3) prevent premature termination of the iteration that occurred under certain conditions, and (4) prevent further adjustment of the gap heat transfer coefficient after reaching the iteration limit. These changes represent a closely-related group of changes. Sample calculations and engineering judgment lead to an estimated PCT impact of 0°F.
WCOBRAITRAC Thermal-Hydraulic History File Dimension Used in HSDRIVER. A problem was identified in the dimension of the WCOBRAITRAC thermal-hydraulic history file used in HSDRIVER. The array that is used to store the information from the WCOBRAITRAC thermal-hydraulic history file is dimensioned to 3000 in HSDRIVER. It is possible for this file to contain more than 3000 curves. If that is the case, it is possible that the curves would not be used correctly in the downstream HOTSPOT execution. An extent-of-condition review indicated that resolution of this issue does not impact the PCT calculation for prior LBLOCA analyses.
Resolution of this issue does not impact the PCT calculation for prior LBLOCA analyses, which leads to a PCT impact of 0°F.
Serial Number 13-361 Docket Nos. 50-305/3361423/338/3391280/281 Attachment 1, Page 11 of 12 WCOBRA/TRAC Automated Restart Process Logic Error. A minor error was identified in the WARP logic for defining the DEG break tables. The error has been evaluated for impact on current licensing-basis analysis results and will be incorporated into the plant-specific analyses on a forward-fit basis. This error was evaluated to have a negligible impact on the Large Break LOCA analysis results, leading to an estimated PCT impact of 0°F.
Evaluation of Additional Containment Metal. Dominion requested that Westinghouse evaluate the impact of additional containment metal on the BE LBLOCA analysis with 15X15 Upgrade Fuel. The containment heat sink revisions were provided by Dominion and their impact was evaluated. The plant-specific evaluation showed that the effect of the changes in containment heat sinks is bounded by the available margin in the analysis, leading to an estimated PCT impact of 0°F for both units.
Evaluation of Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown. Fuel pellet TCD and peaking factor burndown were not explicitly considered in the SPS1 and SPS2 LBLOCA ASTRUM analysis with 15x15 Upgrade Fuel. The NRC Information Notice 2011-21 notified addresses of recent information obtained concerning the impact of irradiation on fuel thermal conductivity and its potential to cause significantly higher predicted PCT in realistic ECCS EMs. This evaluation provides an estimated effect of fuel pellet TCD and peaking factor burndown on the PCT calculation for the ECCS at SPS1 and SPS2. A quantitative evaluation (excluding offsetting effects and the non-uniform radial power profile) was performed to assess the PCT effect of fuel TCD and peaking factor burndown on the SPS1 and SPS2 LBLOCA analysis and concluded that the estimated PCT impact was +183°F for 10 CFR 50.46 reporting purposes.
For SPS1 and SPS2, this issue resulted in the accumulation of changes to the calculated peak fuel cladding temperature to exceed 50°F and was previously reported to the NRC in a letter dated July 10, 2012 (Serial No.12-420) to meet the 30-day reporting requirements of 10 CFR 50.46(a)(3)(ii).
Pellet Radial Profile Option. The radial power profile of fuel pellets in the AOR was assumed to be uniform when setting up the conduction network over the fuel pellet in HOTSPOT. However, the accuracy of this approximation decreases for highly burned fuel since the radial power profile tends to increase from the center towards the outside of the fuel pellet at higher burnups. As such, an option was added in HOTSPOT to use a non-uniform radial power profile consistent with the WCOBRA/TRAC code.
These changes were considered to be a discretionary change for the Westinghouse BE LBLOCA EMs. However, the Surry AOR performed in 2010 did not include the change. A quantitative evaluation was performed to
Serial Number 13-361 Docket Nos. 50-3051336/423/338/339/280/281 Attachment 1, Page 12 of 12 assess the PCT effect of the non-uniform pellet radial power profile in HOTSPOT on the SPS1 and SPS2 LBLOCA analysis and concluded that the estimated PCT impact was -1 3F for 10 CFR 50.46 reporting purposes.
For SPS1 and SPS2, this issue resulted in the accumulation of changes to the calculated peak fuel cladding temperature to exceed 50°F and was previously reported to the NRC in a letter dated July 10, 2012 (Serial No.12-420) to meet the 30-day reporting requirements of 10 CFR 50.46(a)(3)(ii).
Conclusion The LOCA results for KPS, MPS2 and MPS3, NAPS1 and NAPS2, and SPS1 and SPS2 are confirmed in the PCT tables, Attachments 2 through 5, 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. 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 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 2012.
Serial Number 13-361 Docket No. 50-305 ATTACHMENT 2 2012 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 2012 ANNUAL REPORTING OF 10 CFR 50.46 MARGIN UTILIZATION DOMINION ENERGY KEWAUNEE, INC.
KEWAUNEE POWER STATION
Serial Number 13-361 Docket No. 50-305 Attachment 2, Page 1 of 3 10 CFR 50.46 MARGIN UTILIZATION - SMALL BREAK LOCA Plant Name: Kewaunee Power Station Utility Name: Dominion Energy Kewaunee, Inc.
Analysis Information EM: NOTRUMP Limiting Break Size: 3 Inch CL, High Tav Analysis Date: 05/14/02 Vendor: Westinghouse FQ: 2.5 FdH: 1.8 Fuel: 422 Vantage +SGTP(%): 10 Notes: Uprate to 1772 MWt. Effective beginning Cycle 26 Clad Temp ('F)
LICENSING BASIS Analysis of Record PCT 1030 PCT ASSESSMENTS (Delta PCT)
A. Prior ECCS Model Assessments
- 1. Reactor Coolant Pump Reference Conditions 0
- 2. Pressurizer Fluid Volumes 0
- 3. Lower Guide Tube Assembly Weight 0
- 4. Discrepancy in NOTRUMP REST Draindown Calculation 0
- 5. NOTRUMP Bubble Rise/Drift Flux Model 35 Inconsistency Corrections
- 6. NOTRUMP-EM Refined Break Spectrum 0
- 7. Errors in Reactor Vessel Nozzle Data Collections 0
- 8. Pump Weir Resistance Modeling 0
- 9. Errors in Reactor Vessel Lower Plenum Surface Area Calculations 0
- 10. Discrepancy in Metal Masses Used from Drawings 0
- 11. Urania-Gadolinia Pellet Thermal Conductivity Calculation 0
- 12. Pellet Crack and Dish Volume Calculation 0
- 13. Treatment of Vessel Average Temperature Uncertainty 0
- 14. Maximum Fuel Rod Time Step Logic 0
- 15. Radiation Heat Transfer Logic 0
- 16. Interruption of SI during the Switchover to Sump Recirculation 0 B. Planned Plant Modification Evaluations
- 1. None 0 C. 2012 ECCS Model Assessments
- 1. NOTRUMP-EM Evaluation of Fuel Pellet Thermal Conductivity Degradation 0 D. Other
Serial Number 13-361 Docket No. 50-305 Attachment 2, Page 2 of 3 10 CFR 50.46 MARGIN UTILIZATION - LARGE BREAK LOCA Plant Name: Kewaunee Power Station Utility Name: Dominion Energy Kewaunee, Inc.
Analysis Information EM: UPI (1999) Limiting Break Size: Split Analysis Date: 03/25/02 Vendor: Westinghouse FQ: 2.5 FdH: 1.8 Fuel: 422 Vantage + SGTP(%): 10 Notes: Uprate to 1772 MWt. Effective beginning Cycle 26 Clad Temp (IF)
LICENSING BASIS Analysis of Record PCT 2084 PCT ASSESSMENTS (Delta PCT)
A. Prior ECCS Model Assessments
- 1. Pressurizer Fluid Volumes 0
- 2. Vessel Unheated Conductor Noding 0
- 3. Level Boundary Selection 0
- 4. Containment Relative Humidity Assumption 0
- 5. Diffuser Plate Modeling 0
- 6. Downcomer Momentum Area 0
- 7. Revised Blowdown Heatup Uncertainty Distribution 5
- 8. Spacer Grid Heat Transfer Model Inputs 5
- 9. Inconsistent Vessel Vertical Level Modeling 0
- 10. Revised Downcomer Gap Inputs -59
- 11. Core Support Column Heat Slab Discrepancy 0
- 12. HOTSPOT Fuel Relocation Error 10
- 13. Revised Upper Plenum Volume Inputs 0
- 14. Steam Generator Nozzle Volume Accounting Error 0
- 15. Errors in Reactor Vessel Nozzle Data Collections 0
- 16. Lower Plenum Unheated Conductors 0
- 17. HOTSPOT Burst Temperature Logic Errors 0
- 18. Discrepancy in Metal Masses Used From Drawings 0 (Lower Support Plate)
- 19. HOTSPOT Gap Heat Transfer Logic 0
- 20. HOTSPOT Statistical Output Logic 0
- 21. Treatment of Vessel Average Temperature Uncertainty 0
- 22. Treatment of Interfacial Drag Multipliers in Upper 0 Plenum Injection Plants B. Planned Plant Modification Evaluations
- 1. Evaluation of Design Input Changes With Respect -115 To Plant Operation
Serial Number 13-361 Docket No. 50-305 Attachment 2, Page 3 of 3 10 CFR 50.46 MARGIN UTILIZATION - LARGE BREAK LOCA (continued)
Plant Name: Kewaunee Power Station Utility Name: Dominion Energy Kewaunee, Inc.
C. 2012 ECCS Model Assessments
- 1. Evaluation of Fuel Pellet Thermal Conductivity 50 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 D. Other
Serial Number 13-361 Docket Nos. 50-336/423 ATTACHMENT 3 2012 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 2012 ANNUAL REPORTING OF 10 CFR 50.46 MARGIN UTILIZATION DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNITS 2 AND 3
Serial Number 13-361 Docket Nos. 50-336/423 Attachment 3, Page 1 of 5 10 CFR 50.46 MARGIN UTILIZATION - SMALL BREAK LOCA Plant Name: Millstone Power Station, Unit 2 Utility Name: Dominion Nuclear Connecticut, Inc.
Analysis Information EM: PWR Small Break LOCA, S-RELAP5 Based Limiting Break Size: 0.08 ft2 Analysis Date: 01/02 Vendor: AREVA Peak Linear Power: 15.1 kW/ft Notes: None Clad Temp (IF)
LICENSING BASIS Analysis of Record PCT 1941 PCT ASSESSMENTS (Delta PCT)
A. Prior ECCS Model Assessments
- 1. Decay Heat Model Error -133
- 2. Revised SBLOCA Guideline 0
- 3. Core Exit Modeling-Upper Tie Plate Flow Area -22
- 4. Point Kinetics Programming Issue with RELAP5-Based Computer Codes -8
- 5. S-RELAP5 Choked Flow Error with Non-Condensables 0 Present
- 6. Radiation to Fluid Heat Transfer Model Change -64
- 7. RELAP5 Kinetics and Heat Conduction Model 4
- 8. RODEX2 Thermal Conductivity Degradation 0
- 9. Sleicher-Rouse Correlation Modeling 83 B. Planned Plant Modification Evaluations
- 1. None 0 C. 2012 ECCS Model Assessments
- 1. None 0 D. Other
Serial Number 13-361 Docket Nos. 50-336/423 Attachment 3, Page 2 of 5 10 CFR 50.46 MARGIN UTILIZATION - LARGE BREAK LOCA Plant Name: Millstone Power Station, Unit 2 Utility Name: Dominion Nuclear Connecticut, Inc.
Analysis Information EM: SEM/PWR-98 Limiting Break Size: 1.0 DECLG Analysis Date: 11/98 Vendor: AREVA 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 of Reflood -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 Gadolinia 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 SG Tube Exit Junction Inertia 0
- 16. RFPAC 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 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
Serial Number 13-361 Docket Nos. 50-336/423 Attachment 3, Page 3 of 5 10 CFR 50.46 MARGIN UTILIZATION - LARGE BREAK LOCA (continued)
Plant Name: Millstone Power Station, Unit 2 Utility Name: Dominion Nuclear Connecticut, Inc.
C. 2012 ECCS Model Assessments
- 1. None 0 D. Other
Serial Number 13-361 Docket Nos. 50-336/423 Attachment 3, Page 4 of 5 10 CFR 50.46 MARGIN UTILIZATION - SMALL BREAK LOCA Plant Name: Millstone Power Station, Unit 3 Utility Name: Dominion 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 B. Planned Plant Modification Evaluations
- 1. None 0 C. 2012 ECCS Model Assessments
- 1. NOTRUMP-EM Evaluation of Fuel Pellet Thermal 0 Conductivity Degradation D. Other
Serial Number 13-361 Docket Nos. 50-336/423 Attachment 3, Page 5 of 5 10 CFR 50.46 MARGIN UTILIZATION - LARGE BREAK LOCA Plant Name: Millstone Power Station, Unit 3 Utility Name: Dominion 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 I. 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 Dr awings 0
- 5. Error in ASTRUM Processinn of Averaae Rod Burnup and Rod Internal Pressure 0
- 6. Treatment of Vessel Average Temperature Uncertainty 0
- 7. Error in ASTRUM Processing of Average Rod Burnup 0
- 8. PBOT and PMID Evaluation 0 B. Planned Plant Modification Evaluations
- 1. None 0 C. 2012 ECCS Model Assessments
- 1. Evaluation of Fuel Pellet Thermal Conductivity 222 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 D. Other I. None 0 LICENSING BASIS PCT + PCT ASSESSMENTS PCT = 2003
Serial Number 13-361 Docket Nos. 50-338/339 ATTACHMENT 4 2012 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 2012 ANNUAL REPORTING OF 10 CFR 50.46 MARGIN UTILIZATION VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2
Serial Number 13-361 Docket No. 50-338/339 Attachment 4, Page 1 of 10 10 CFR 50.46 MARGIN UTILIZATION - AREVA SMALL BREAK LOCA Plant Name: North Anna Power Station, Unit 1 Utility Name: Virginia Electric and Power Company Analysis Information EM: AREVA SB EM Limiting Break Size: 5.2 Inches (SI Line)
Analysis Date: 2004 Vendor: AREVA FQ: 2.32 FAH: 1.65 Fuel: Advanced Mark-BW SGTP (%): 7 Notes: None Clad Temp (IF)
LICENSING BASIS Analysis of Record PCT 1404 PCT ASSESSMENTS (Delta PCT)
A. Prior ECCS Model Assessments
- 1. Point Kinetics Programming Issue with RELAP5-Based Computer Codes -8
- 2. RCCA Reactivity Input -3
- 3. Critical Flow Transition 26
- 4. RELAP5 Kinetics and Heat Conduction Model 0
- 5. TACO3 - Thermal Conductivity Degradation 0
- 6. Revised Test Flow Curve for HHSI -24
- 7. Advanced Mark BW Top Nozzle Modification 0 B. Planned Plant Modification Evaluations
- 1. None 0 C. 2012 ECCS Model Assessments
- 1. None 0 D. Other
Serial Number 13-361 Docket No. 50-338/339 Attachment 4, Page 2 of 10 10 CFR 50.46 MARGIN UTILIZATION - AREVA LARGE BREAK LOCA Plant Name: North Anna Power Station, Unit 1 Utility Name: Virginia Electric and Power Company Analysis Information EM: AREVA RLBLOCA EM Limiting Break Size: DEGB Analysis Date: 2004 Vendor: AREVA FQ: 2.32 FAH: 1.65 Fuel: Advanced Mark-BW SGTP (%): 12 Notes: None Clad Temp (°F)
LICENSING BASIS Analysis of Record PCT 1853 PCT ASSESSMENTS (Delta PCT)
A. Prior ECCS Model Assessments
- 1. Forslund-Rohsenow Correlation Modeling 64
- 2. RWST Temperature Assumption 8
- 3. LBLOCA/Seismic SG Tube Collapse 0
- 4. ICECON Code Errors 0
- 5. RLBLOCA Choked Flow Disposition -26
- 6. RLBLOCA Changes in Uncertainty Parameters 10
- 7. Blowdown Quench 0
- 8. Mixture Level Model Limitation in the S-RELAP5 Code -29
- 9. Point Kinetics Programming Issue with RELAP5-Based Computer Codes -20
- 10. Cold Leg Condensation Under Predicted by S-RELAP5 Following Accumulator Injection 0
- 11. Cross-Flow Junction Area in S-RELAP Model 0
- 12. Radiation to Fluid Heat Transfer Model Change -32
- 13. S-RELAP5 Kinetics and Heat Conduction Model -29
- 14. RODEX3A - Thermal Conductivity Degradation 0
- 15. Steam Generator Entrainment Bias Factor (FIJ) Change -4
- 16. Advanced Mark-BW Top Nozzle Modification 65
- 17. GSI-191 Sump Strainer 0
- 18. MUR Implementation 2
- 19. RLBLOCA Upper Plenum Modeling 8
- 20. Sleicher-Rouse Correlation Modeling 14 B. Planned Plant Modification Evaluations
- 1. None 0
Serial Number 13-361 Docket No. 50-338/339 Attachment 4, Page 3 of 10 10 CFR 50.46 MARGIN UTILIZATION - AREVA LARGE BREAK LOCA (continued)
Plant Name: North Anna Power Station, Unit 1 Utility Name: Virginia Electric and Power Company C. 2012 ECCS Model Assessments
- 1. Liquid Fallback into Surrounding 6 Assemblies -8
- 2. Cathcart-Pawel Uncertainty Implementation 0 in RLBLOCA Applications D. Other
Serial Number 13-361 Docket No. 50-338/339 Attachment 4, Page 4 of 10 10 CFR 50.46 MARGIN UTILIZATION - AREVA SMALL BREAK LOCA Plant Name: North Anna Power Station, Unit 2 Utility Name: Virginia Electric and Power Company Analysis Information EM: AREVA SB EM Limiting Break Size: 3 Inches Analysis Date: 2004 Vendor: AREVA FQ: 2.32 FAH: 1.65 Fuel: Advanced Mark-BW SGTP (%): 7 Notes: None Clad Temp (*F)
LICENSING BASIS Analysis of Record PCT 1370 PCT ASSESSMENTS (Delta PCT)
A. Prior ECCS Model Assessments
- 1. Point Kinetics Programming Issue with RELAP5-Based Computer Codes -8
- 2. RCCA Reactivity Input -29
- 3. Critical Flow Transition 5
- 4. RELAP5 Kinetics and Heat Conduction Model 0
- 5. TACO3 - Thermal Conductivity Degradation 0
- 6. Advanced Mark BW Top Nozzle Modification 0 B. Planned Plant Modification Evaluations
- 1. None 0 C. 2012 ECCS Model Assessments
- 1. None 0 D. Other
Serial Number 13-361 Docket No. 50-338/339 Attachment 4, Page 5 of 10 10 CFR 50.46 MARGIN UTILIZATION - AREVA LARGE BREAK LOCA Plant Name: North Anna Power Station, Unit 2 Utility Name: Virginia Electric and Power Company Analysis Information EM: AREVA RLBLOCA EM Limiting Break Size: DEGB Analysis Date: 2004 Vendor: AREVA FQ: 2.32 FAH: 1.65 Fuel: Advanced Mark-BW SGTP (%): 12 Notes: None Clad Temp (IF)
LICENSING BASIS Analysis of Record PCT 1789 PCT ASSESSMENTS (Delta PCT)
A. Prior ECCS Model Assessments
- 1. Forslund-Rohsenow Correlation Modeling 64
- 2. RWST Temperature Assumption 8
- 3. LBLOCA/Seismic SG Tube Collapse 0
- 4. ICECON Code Errors 0
- 5. RLBLOCA Choked Flow Disposition 22
- 6. RLBLOCA Changes in Uncertainty Parameters 10
- 7. Mixture Level Model Limitation in the S-RELAP5 Code - -19
- 8. Point Kinetics Programming Issue with RELAP5-Based Computer Codes -20
- 9. Cold Leg Condensation Under Predicted by S-RELAP5 Following Accumulator Injection 0
- 10. Cross-Flow Junction Area in S-RELAP Model 0
- 11. Radiation to Fluid Heat Transfer Model Change -32
- 12. S-RELAP5 Kinetics and Heat Conduction Model -29
- 13. RODEX3A - Thermal Conductivity Degradation 0
- 14. Steam Generator Entrainment Bias Factor (FIJ) Change -4
- 15. Advanced Mark-BW Top Nozzle Modification 65
- 16. GSI-191 Sump Strainer 0
- 17. MUR Implementation 20
- 18. RLBLOCA Upper Plenum Modeling 0
- 19. Sleicher-Rouse Correlation Modeling 14 B. Planned Plant Modification Evaluations
- 1. None 0
Serial Number 13-361 Docket No. 50-338/339 Attachment 4, Page 6 of 10 10 CFR 50.46 MARGIN UTILIZATION - AREVA LARGE BREAK LOCA (continued)
Plant Name: North Anna Power Station, Unit 2 Utility Name: Virginia Electric and Power Company C. 2012 ECCS Model Assessments
- 1. Liquid Fallback into Surrounding 6 Assemblies 31
- 2. Cathcart-Pawel Uncertainty Implementation 0 in RLBLOCA Applications D. Other
Serial Number 13-361 Docket No. 50-338/339 Attachment 4, Page 7 of 10 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 FAH: 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 I. None 0 B. Planned Plant Modification Evaluations
- 1. None 0 C. 2012 ECCS Model Assessments
- 1. NOTRUMP-EM Evaluation of Fuel Pellet Thermal 0 Conductivity Degradation D. Other I. None 0 LICENSING BASIS PCT + PCT ASSESSMENTS PCT = 1834.1
Serial Number 13-361 Docket No. 50-338/339 Attachment 4, Page 8 of 10 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 FAH: 1.65 Fuel: RFA-2 SGTP (%): 7 Notes: Core Power < 100% of 2951 MWt; SG Model 54F; 17xl7 RFA-2 Fuel with ZIRLO or Optimized ZIRLOTM cladding, Non-IFBA or IFBA, IFMs Clad Temp (fF)
LICENSING BASIS Analysis of Record PCT 1852 PCT ASSESSMENTS (Delta PCT)
A. Prior ECCS Model Assessments
- 1. None 0 B. Planned Plant Modification Evaluations I. None 0 C. 2012 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 D. Other
Serial Number 13-361 Docket No. 50-338/339 Attachment 4, Page 9 of 10 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 FAH: 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. None 0 B. Planned Plant Modification Evaluations
- 1. None 0 C. 2012 ECCS Model Assessments
- 1. NOTRUMP-EM Evaluation of Fuel Pellet Thermal 0 Conductivity Degradation D. Other
Serial Number 13-361 Docket No. 50-338/339 Attachment 4, Page 10 of 10 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: 8/20/2010 Vendor: Westinghouse FQ: 2.32 FAH: 1.65 Fuel: RFA-2 SGTP (%): 7 Notes: Core Power!< 100% of 2951 MWt; SG Model 54F; 17x17 RFA-2 Fuel with ZIRLO or Optimized ZIRLOTM cladding, Non-IFBA or IFBA, IFMs Clad Temp (*F)
LICENSING BASIS Analysis of Record PCT 1871 PCT ASSESSMENTS (Delta PCT)
A. Prior ECCS Model Assessments
- 1. None 0 B. Planned Plant Modification Evaluations
- 1. None C. 2012 ECCS Model Assessments
- 1. Evaluation of Fuel Pellet Thermal Conductivity 101 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 D. Other
Serial Number 13-361 Docket Nos. 50-280/281 ATTACHMENT 5 2012 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 2012 ANNUAL REPORTING OF 10 CFR 50.46 MARGIN UTILIZATION VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2
Serial Number 05-361 Docket Nos. 50-280/281 Attachment 5, Page 1 of 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 FAH: 1.7 Fuel: Mixed: Upgrade/SIF SGTP (%): 7 Notes: None Clad Temp (IF)
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 B. Planned Plant Modification Evaluations
- 1. None 0 C. 2012 ECCS Model Assessments
- 1. NOTRUMP-EM Evaluation of Fuel Pellet Thermal 0 Conductivity Degradation D. Other
Serial Number 13-361 Docket Nos. 50-280/281 Attachment 5, Page 2 of 4 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE LARGE BREAK LOCA WITH ASTRUM 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 FAH: 1.7 Fuel: Mixed:Upgrade/SIF SGTP (%): 7 Notes: None Clad Temp (IF)
LICENSING BASIS Analysis of Record PCT 1853 PCT ASSESSMENTS (Delta PCT)
A. Prior ECCS Model Assessments
- 1. Transition Core (applied to mixed SIF/Upgrade core only) 14 B. Planned Plant Modification Evaluation I. Evaluation of Additional Containment Metal 0 C. 2012 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 D. Other
I Serial Number 13-361 Docket Nos. 50-280/281 Attachment 5, Page 3 of 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 FAH: 1.7 Fuel: Mixed: Upgrade/SIF 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 B. Planned Plant Modification Evaluations
- 1. None 0 C. 2012 ECCS Model Assessments
- 1. NOTRUMP-EM Evaluation of Fuel Pellet Thermal 0 Conductivity Degradation D. Other
Serial Number 13-361 Docket Nos. 50-280/281 Attachment 5, Page 4 of 4 10 CFR 50.46 MARGIN UTILIZATION - WESTINGHOUSE LARGE BREAK LOCA WITH ASTRUM 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 FAH: 1.7 Fuel: Mixed: Upgrade/SIF SGTP (%): 7 Notes: None Clad Temp (°F)
LICENSING BASIS Analysis of Record PCT 1853 PCT ASSESSMENTS (Delta PCT)
A. Prior ECCS Model Assessments
- 1. Transition Core (applied to mixed SIF/Upgrade core only) 14 B. Planned Plant Modification Evaluations
- 1. Evaluation of Additional Containment Metal 0 C. 2012 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 D. Other