RC-09-0050, Submittal of 2008 Emergency Core Cooling System (ECCS) Evaluation Model Revisions Report

Submittal of 2008 Emergency Core Cooling System (ECCS) Evaluation Model Revisions Report

ML091390218
Person / Time
Site:	Summer
Issue date:	05/14/2009
From:	Archie J South Carolina Electric & Gas Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LTD 321, RC-09-0050
Download: ML091390218 (13)

Text

Jeffrey B. Archie Vice President,Nuclear Operations 803.345.4214 May 14, 2009 A SCANA COMPANY Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

VIRGIL C. SUMMER NUCLEAR STATION DOCKET NO. 50/395 OPERATING LICENSE NO. NPF-12 ECCS EVALUATION MODEL REVISIONS REPORT South Carolina Electric & Gas Company (SCE&G), acting for itself and as agent for South Carolina Public Service Authority hereby submits the 2008 Emergency Core Cooling System (ECCS) Evaluation Model Revisions Annual Report for the Virgil C.

Summer Nuclear Station (VCSNS). This report is being submitted pursuant to 10 CFR 50.46, which requires licensees to notify the NRC on at least an annual basis of corrections to or changes in the ECCS Evaluation Models.

Summary sheets describing changes and enhancements to the ECCS Evaluation Models for 2008 are included in Attachment I. Peak Clad Temperature (PCT) sheets are included in Attachment I1.

If you have any questions, please call Mr. Bruce L. Thompson at (803) 931-5042.

GAR/JBA/dr Attachments c: K. B. Marsh R. E. Martin S. A. Byrne NRC Resident Inspector N. S. Carns K. M. Sutton J. H. Hamilton NSRC R. J. White RTS (LTD 321, RR 8375)

K. J. Browne File (818.02-17)

L. A. Reyes PRSF (RC-09-0050)

SCE&G I Virgil C.Summer Nuclear Station

• P.0. Box 88 . Jenkinsville, South Carolina 29065 -T (803) 345.5209 www.scona.com

Document Control Desk Attachment I LTD 321 RC-09-0050 Page 1 of 5 Attachment I Changes and Enhancements to the ECCS Evaluation Models for 2008

Document Control Desk Attachment I LTD 321 RC-09-0050 Page 2 of 5 ERRORS IN REACTOR VESSEL LOWER PLENUM SURFACE AREA CALCULATIONS (Non-Discretionary Change)

Background

Two errors were discovered in the calculations of reactor vessel lower plenum surface area. The corrected values have been evaluated for impact on current licensing-basis analysis results and will be incorporated on a forward-fit basis. These changes represent a closely-related group of Non-Discretionary Changes in accordance with Section 4.1.2 of WCAP- 13451.

Affected Evaluation Models 1985 Westinghouse Small Break LOCA Evaluation Model with NOTRUMP Estimated Effect The differences in vessel lower plenum surface area are relatively minor and would be expected to produce a negligible effect on small break LOCA analysis results, leading to an estimated PCT impact of 0°F for 10 CFR 50.46 reporting purposes.

DISCREPANCY IN METAL MASSES USED FROM DRAWINGS (Non-Discretionary Change)

Background

Discrepancies were discovered in the use of metal masses from drawings. The updated reactor vessel metal masses and fluid volumes have been evaluated for impact on current licensing-basis analysis results and will be incorporated on a forward-fit basis. These changes represent a closely-related group of Non-Discretionary Changes in accordance with Section 4.1.2 of WCAP-13451.

Affected Evaluation Model 1985 Westinghouse Small Break LOCA Evaluation Model with NOTRUMP Estimated Effect The differences in the reactor vessel metal mass and fluid volume are relatively minor and would be expected to produce a negligible effect on small break LOCA analysis results, leading to an estimated PCT impact of 00 F for 10 CFR 50.46 reporting purposes.

Document Control Desk Attachment I LTD 321 RC-09-0050 Page 3 of 5 GENERAL CODE MAINTENANCE (Discretionary Change)

Background

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. These changes represent Discretionary Changes that will be implemented on a forward-fit basis in accordance with Section 4.1.1 of WCAP-13451.

Affected Evaluation Model 1985 Westinghouse Small Break LOCA Evaluation Model with NOTRUMP Estimated Effect The nature of these changes leads to an estimated PCT impact of 0°F.

,GENERAL CODE MAINTENANCE (Discretionary Change)

Background

A number of coding changes were made as part of normal code maintenance. Examples include additional information in code outputs, improved automation and diagnostics in the codes, increased code dimensions, and general code cleanup. All of these changes are considered to be Discretionary Changes in accordance with Section 4.1.1 of WCAP- 13451.

Affected Evaluation Model 1996 Westinghouse Best Estimate Large Break LOCA Evaluation Model Estimated Effect The nature of these changes leads to an estimated PCT impact of 0°F for 10 CFR 50.46 reporting purposes.

Document Control Desk Attachment I LTD 321 RC-09-0050 Page 4 of 5 HOTSPOT BURST TEMPERATURE LOGIC ERRORS (Non-Discretionary Change)

Background

The HOTSPOT code has been updated to incorporate the following corrections to the burst temperature logic: (1) change the rod internal pressure used to calculate the cladding engineering hoop stress from the value in the previous time step to the value in the current time step; (2) revise the average cladding heat-up rate calculation to reset selected variables to zero at the beginning of each trial and use the instantaneous heat-up rate when fewer than five values are available; and, (3) reflect the assumed saturation of ramp rate effects above 28°C/s for Zircaloy-4 cladding from Equation 7-66 of Reference 1. These changes represent a closely-related group of Non-Discretionary Changes in accordance with Section 4.1.2 of WCAP- 13451.

Affected Evaluation Model 1996 Westinghouse Best Estimate Large Break LOCA Evaluation Model Estimated Effect Sample calculations for each change showed no effect on peak cladding temperature, leading to an estimated impact of 0°F for 10 CFR 50.46 reporting purposes.

Reference

1. WCAP-12945-P-A, Volume 1 (Revision 2) and Volumes 2-5 (Revision 1),

"Code Qualification Document for Best Estimate LOCA Analysis," S. M. Bajorek et al.,

March 1998.

Document Control Desk Attachment I LTD 321 RC-09-0050 Page 5 of 5 MODELING OF ANNULAR PELLETS (Non-Discretionary Change)

Background

It was identified that annular pellets were not addressed in the VCSNS small break loss-of-coolant accident (SBLOCA) analysis of record (AOR). A plant specific evaluation was completed to estimate the effect of modeling annular pellets in the VCSNS SBLOCA analysis.

This change represents a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451.

Affected Evaluation Model 1985 Appendix K Small Break LOCA Evaluation Model with NOTRUMP Estimated Effect A plant specific evaluation of annular pellets on the limiting peak cladding temperature (PCT) and limiting transient oxidation break sizes was performed. The evaluation determined that annular pellets have a negligible effect on the VCSNS SBLOCA analysis results, leading to an estimated PCT impact of 00 F for 10 CFR 50.46 reporting purposes.

PCT ASSESSMENT OF TRANSVERSE MOMENTUM CELLS FOR ZERO CROSS-FLOW BOUNDARY CONDITION ERROR IN THE VCSNS BEST-ESTIMATE LARGE BREAK LOCA ANALYSIS (Non-Discretionary Change)

Background

An error was identified in the calculation of the transverse momentum cells for zero cross-flow boundary condition during the course of performing a Best-Estimate Large Break LOCA (BE LBLOCA) evaluation to assess the impact of a conversion of the barrel-baffle region to an upflow configuration. A plant specific evaluation was performed using the WCOBRA/TRAC code to estimate the effect of the error discovered in the VCSNS BE LBLOCA analysis.

Affected Evaluation Model 1996 Westinghouse Best Estimate Large Break LOCA Evaluation Model Estimated Effect The VCSNS Reference Transient was re-run using WCOBRA/TRAC to establish an estimated effect on the PCT. This evaluation resulted in a I°F increase in PCT during the Blowdown period, a 9°F reduction in PCT during the Reflood 1 period, and a 14'F reduction in PCT during the Reflood 2 period. Based on these results, it is concluded that VCSNS continues to maintain a margin of safety to the limits prescribed by 10 CFR 50.46.

Document Control Desk Attachment II LTD 321 RC-09-0050 Page 1 of 7 Attachment II PCT Rackup Sheets

Document Control Desk Attachment II LTD 321 RC-09-0050 Page 2 of 7 Westinghouse LOCA Peak Clad Temperature Summary for Best Estimate Large Break Plant Name: V. C. Summer Utility Name: South Carolina Electric & Gas Revision Date: 1/27/09 Composite Analysis Information EM: CQD (1996) Analysis Date: 2/3/03 Limiting Break Size: Guillotine FQ: 2.5 FdH: 1.7 Fuel: Vantage + SGTP (%): 10 Notes: Delta 75 Replacement Steam Generator Uprate Core Power 2900 MWt Clad Temp ('F) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 1988 1 PCT ASSESSMENTS (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS

1. Backfit Through 2001 Reporting Year 0 2

2. Revised Blowdown Heatup Uncertainty Distribution 5 3 B. PLANNED PLANT MODIFICATION EVALUATIONS

1. Fan Cooler Performance Increase 2 2 C. 2008 ECCS MODEL ASSESSMENTS

1. Transverse Momentum Cells for Zero Cross-flow Boundary Condition -14 4 Error D. OTHER

1. None 0 LICENSING BASIS PCT + PCT ASSESSMENTS PCT= 1981

References:

1. WCAP- 16043, "Best Estimate Analysis of the Large Break Loss of Coolant Accident for the Virgil C.

Summer Nuclear Station," June 2003.

2. CGE-03-12, "10 CFR 50.46 Annual Notification and Reporting for 2002," March 2003.

3. CGE-05-20, "10 CFR 50.46 Annual Notification and Reporting for 2004," April 2005.

4. LTR-LIS-08-578, Revision 2, "Large Break LOCA Evaluation for V. C. Summer (CGE) Upflow Conversion and Assessment of Transverse Momentum Cells for Zero Cross-flow Boundary Condition Error," January 2009.

Notes:

None

Document Control Desk Attachment II LTD 321 RC-09-0050 Page 3 of 7 Westinghouse LOCA Peak Clad Temperature Summary for Best Estimate Large Break Plant Name: V. C. Summer Utility Name: South Carolina Electric & Gas Revision Date: 1/27/09 Blowdown Analysis Information EM: CQD (1996) Analysis Date: 2/3/03 Limiting Break Size: Guillotine FQ: 2.5 FdH: 1.7 Fuel: Vantage + SGTP (%): 10 Notes: Delta 75 Replacement Steam Generator Uprate Core Power 2900 MWt Clad Temp ('F) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 1860 1 PCT ASSESSMENTS (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS

1. Backfit Through 2001 Reporting Year 0 2

2. Revised Blowdown Heatup Uncertainty Distribution 49 3 B. PLANNED PLANT MODIFICATION EVALUATIONS

1. Fan Cooler Performance Increase 0 2 C. 2008 ECCS MODEL ASSESSMENTS

1. Transverse Momentum Cells for Zero Cross-flow Boundary Condition 1 4 Error D. OTHER

1. None 0 LICENSING BASIS PCT + PCT ASSESSMENTS PCT = 1910

References:

1. WCAP-16043, "Best Estimate Analysis of the Large Break Loss of Coolant Accident for the Virgil C.

Summer Nuclear Station," June 2003.

2. CGE-03-12, "10 CFR 50.46 Annual Notification and Reporting for 2002," March 2003.

3. CGE-05-20, "10 CFR 50.46 Annual Notification and Reporting for 2004," April 2005.

4. LTR-LIS-08-578, Revision 2, "Large Break LOCA Evaluation for V. C. Summer (CGE) Upflow Conversion and Assessment of Transverse Momentum Cells for Zero Cross-flow Boundary Condition Error," January 2009.

Notes:

None

Document Control Desk Attachment II LTD 321 RC-09-0050 Page 4 of 7 Westinghouse LOCA Peak Clad Temperature Summary for Best Estimate Large Break Plant Name: V. C. Summer Utility Name: South Carolina Electric & Gas Revision Date: 1/27/09 Reflood 1 Analysis Information EM: CQD (1996) Analysis Date: 2/3/03 Limiting Break Size: Guillotine FQ: 2.5 FdH: 1.7 Fuel: Vantage + SGTP (%): 10 Notes: Delta 75 Replacement Steam Generator Uprate Core Power 2900 MWt Clad Temp ('F) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 1808 1 PCT ASSESSMENTS (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS

1. Backfit Through 2001 Reporting Year 0 2

2. Revised Blowdown Heatup Uncertainty Distribution 5 3 B. PLANNED PLANT MODIFICATION EVALUATIONS

1. Fan Cooler Performance Increase 1 2 C. 2008 ECCS MODEL ASSESSMENTS

1. Transverse Momentum Cells for Zero Cross-flow Boundary Condition -9 4 Error D. OTHER

1. None 0 LICENSING BASIS PCT + PCT ASSESSMENTS PCT= 1805

References:

1. WCAP- 16043, "Best Estimate Analysis of the Large Break Loss of Coolant Accident for the Virgil C.

Summer Nuclear Station," June 2003.

2. CGE-03-12, "10 CFR 50.46 Annual Notification and Reporting for 2002," March 2003.

3. CGE-05-20, "10 CFR 50.46 Annual Notification and Reporting for 2004," April 2005.

4. LTR-LIS-08-578, Revision 2, "Large Break LOCA Evaluation for V. C. Summer (CGE) Upflow Conversion and Assessment of Transverse Momentum Cells for Zero Cross-flow Boundary Condition Error," January 2009.

Notes:

None

Document Control Desk Attachment II LTD 321 RC-09-0050 Page 5 of 7 Westinghouse LOCA Peak Clad Temperature Summary for Best Estimate Large Break Plant Name: V. C. Summer Utility Name: South Carolina Electric & Gas Revision Date: 1/27/09 Reflood 2 Analysis Information EM: CQD (1996) Analysis Date: 2/1/03 Limiting B]reak Size: Guillotine FQ: 2.5 FdH: 1.7 Fuel: Vantage + SGTP (%): 10 Notes: Delta 75 Replacement Steam Generator Uprate Core Power 2900 MWt Clad Temp ('F) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 1988 1 PCT ASSESSMENTS (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS

1. Backfit Through 2001 Reporting Year 0 2

2. Revised Blowdown Heatup Uncertainty Distribution 5 3 B. PLANNED PLANT MODIFICATION EVALUATIONS

1. Fan Cooler Performance Increase 2 2 C. 2008 ECCS MODEL ASSESSMENTS

1. Transverse Momentum Cells for Zero Cross-flow Boundary Condition -14 4 Error D. OTHER

1. None 0 LICENSING BASIS PCT + PCT ASSESSMENTS PCT = 1981

References:

1. WCAP- 16043, "Best Estimate Analysis of the Large Break Loss of Coolant Accident for the Virgil C.

Summer Nuclear Station," June 2003.

2. CGE-03-12, "10 CFR 50.46 Annual Notification and Reporting for 2002," March 2003.

3. CGE-05-20, "10 CFR 50.46 Annual Notification and Reporting for 2004," April 2005.

4. LTR-LIS-08-578, Revision 2, "Large Break LOCA Evaluation for V. C. Summer (CGE) Upflow Conversion and Assessment of Transverse Momentum Cells for Zero Cross-flow Boundary Condition Error," January 2009.

Notes:

None

Document Control Desk Attachment II LTD 321 RC-09-0050 Page 6 of 7 Westinghouse LOCA Peak Clad Temperature Summary for Appendix K Small Break Plant Name: V. C. Summer Utility Name: South Carolina Electric & Gas Revision Date: 1/27/09 Analysis Information EM: NOTRUMP Analysis Date: 9/12/06 Limiting Break Size: 3 Inch FQ: 2.4 FdH: 1.62 Fuel: Vantage + SGTP (%): 10 Notes:

Clad Temp ('F) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 1775 9 (a)

PCT ASSESSMENTS (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS

1. None 0 B. PLANNED PLANT MODIFICATION EVALUATIONS

1. None 0 C. 2008 ECCS MODEL ASSESSMENTS

1. None 0 D. OTHER

1. None 0 LICENSING BASIS PCT + PCT ASSESSMENTS PCT = 1775

References:

I. CGE-94-205, "South Carolina Electric and Gas Company, Virgil C. Summer Station, 10 CFR 50.46 Notification and Reporting Information," February 8, 1994.

2. CGE-94-228, "South Carolina Electric and Gas Company, Virgil C. Summer Station, SBLOCTA Axial Nodalization," October 27, 1994.

3. CGE-95-201, "South Carolina Electric and Gas Company, Virgil C. Summer Station, 10 CFR 50.46 Notification and Reporting Information," February 3, 1995.

4. CGE-96-202, "South Carolina Electric and Gas Company, Virgil C. Summer Station, 10 CFR 50.46 Annual Notification and Reporting," February 9, 1996.

5. CGE-96-213, "South Carolina Electric and Gas Company, Virgil C. Summer Station, 10 CFR 50.46 Small Break LOCA Notification and Reporting," July 8, 1996.

6. CGE-00-044, "South Carolina Electric and Gas Company, Virgil C. Summer Nuclear Station, 10 CFR 50.46 Appendix K (BART / BASH / NOTRUMP) Evaluation Model, Mid-Year Notification and Reporting for 2000," June 30, 2000.

7. CGE-03-80, "10 CFR 50.46 Mid-Year Notification and Reporting for 2003," January 2004.

8. LTR-LIS-06-344, "Transmittal of Updated V. C. Summer SBLOCA PCT Rackup Sheets," November 2006.

9. LTR-LIS-06-662, Transmittal of V. C. Summer SBLOCTA PCT Rackup Sheets for HHSI Throttle Valve Replacement," November 2006.

Document Control Desk Attachment II LTD 321 RC-09-0050 Page 7 of 7 Notes:

(a) The Rebaseline Analysis includes the impacts of the following model assessments:

1-LUCIFER Error Corrections (Ref. 1) 2-Effect of SI in Broken Loop (Ref. 1) 3-Effect of Improved Condensation Model (Ref. 1) 4-Axial Nodalization, RIP Model Revision and SBLOCTA Error Corrections Analysis (Ref. 2) 5-Boiling Heat Transfer Error (Ref. 3) 6-Steam Line Isolation Logic Error (Ref. 3) 7-NOTRUMP Specific Enthalpy Error (Ref. 4) 8-SALIBRARY Double Precision Error (Ref. 4) 9-SBLOCTA Fuel Rod Initialization Error (Ref. 5) 10-NOTRUMP Mixture Level Tracking / Region Depletion Errors (Ref. 6) 1I-NOTRUMP Bubble Rise / Drift Flux Model Inconsistency Corrections (Ref. 7) 12-Refined Break Spectrum (Ref. 8) 13-High Head Safety Injection (HHSI) Flow Increase (Ref. 9)