ML11207A457
| ML11207A457 | |
| Person / Time | |
|---|---|
| Site: | Mcguire, Catawba, McGuire  |
| Issue date: | 07/21/2011 |
| From: | Baxter D Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML11207A457 (6) | |
Text
Dave Baxter Duke 10 CFR 50.46 Vice President (WEnergy Nuclear Engineering Duke Energy Corporation 526 South Church Street Charlotte, NC 28202 Mailing Address:
EC08H / P. 0. Box 1006 Charlotte, NC 28201-1006 July 21, 2011 7043824712 704 382 7852 fax U. S. Nuclear Regulatory Commission Washington, D. C. 20555-001 David.Baxter@duke-energy.corn Attention: Document Control Desk
Subject:
Duke Energy Carolinas, LLC (Duke Energy)
McGuire Nuclear Station, Units 1 and 2 Docket Numbers 50-369 and 50-370 Catawba Nuclear Station, Units 1 and 2 Docket Numbers 50-413 and 50-414 Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model 10 CFR 50.46(a)(3)(ii) requires the reporting of changes to or errors in the Emergency Core Cooling System (ECCS) evaluation models (EMs). This report covers the time period from January 1, 2010 to December 31, 2010.
During this time period, there were no errors or evaluation model changes identified by Westinghouse that exhibited changes to the peak cladding temperature (PCT) results.
However, three non-discretionary changes were made to the large break loss of coolant accident (LBLOCA) EM. The specific details of these changes are provided in Table 1, and were not considered to have an impact on the calculated PCTs. Since there was no PCT impact due to these non-discretionary changes, they are not included in the PCT summary tables.
For completeness, Westinghouse also informed Duke Energy of a number of discretionary coding changes that were made as part of normal code maintenance and general code cleanup for the small break LOCA analyses. Specific details of these changes are also provided in Table 1 and were not considered to have an impact on the calculated PCTs. As such, they are not included in the PCT summary tables.
All McGuire and Catawba units were loaded with cores comprised entirely of Westinghouse fuel for the calendar year 2010. Therefore, no transition core PCT penalties are included in the PCT summary tables.
Table 2 provides the PCT summary for McGuire Units 1 and 2 and Catawba Unit 1, and Table 3 provides the PCT summary for Catawba Unit 2.
There are no regulatory commitments associated with this letter.
www.duke-energy.com
U.S. Nuclear Regulatory Commission July 21, 2011 Page 2 Please address any comments or questions regarding this matter to L. B. Jones at (704) 382-4753.
Sincerely, David A. Baxter Vice President, Nuclear Engineering Attachments Table 1 Errors/Evaluation Model Changes with no PCT Impact Table 2 Peak Cladding Temperature Summary - McGuire Units I & 2 and Catawba Unit 1 Table 3 Peak Cladding Temperature Summary - Catawba Unit 2 xc: (with attachments)
V. M. McCree, Region II Administrator U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Avenue NE, Suite 1200 Atlanta, GA 30303-1257 J. H. Thompson, Project Manager (CNS & MNS)
U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 G9A Rockville, MD 20852-2738 J. Zeiler, NRC Senior Resident Inspector McGuire Nuclear Station A. Hutto, Ill, NRC Senior Resident Inspector Catawba Nuclear Station
ATTACHMENTS Table I - Errors/Evaluation Model Changes with no PCT Impact Table 2 - Peak Cladding Temperature Summary McGuire Units I & 2 and Catawba Unit I Table 3 - Peak Cladding Temperature Summary - Catawba Unit 2
Table I Errors / Evaluation Model Changes with no PCT Impact Discretionary Changes:
General Code Maintenance Affected Evaluation Model(s): SBLOCA, 1985 NOTRUMP Model Various changes were made to enhance the usability of the codes and to help preclude errors in 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 code changes leads to an estimated PCT impact of 0°F.
Non-Discretionary Changes:
Urania-Gadolinia Pellet Thermal Conductivity Calculation Affected Evaluation Model(s): SBLOCA, 1985 NOTRUMP Model Two errors were discovered in the pellet thermal conductivity calculation for urania-gadolinia pellets in the SBLOCTA code. First, the calculation did not include the terms required to adjust for pellet densities other than 95% of the theoretical density. Second, the conversion from Fahrenheit to Rankine used an adder of 459 instead of 459.67. These errors have been corrected and evaluated for impact on existing Small Break LOCA analysis results. SBLOCTA sensitivity calculations led to an estimated PCT effect of 0°F for existing Small Break LOCA analysis results.
Pellet Crack and Dish Volume Calculation Affected Evaluation Model(s): SBLOCA, 1985 NOTRUMP Model Two errors were discovered in the calculation of the normalized pellet crack and dish volumes in the SBLOCTA code. First, an incorrect operator was used to select between two tables of normalized volume vs. linear heat generation rate. Second, the normalized volume at 18 kW/ft was incorrectly programmed in one of the tables as 1.58 instead of 1.59. These errors have been corrected in the SBLOCTA code and will be corrected (where applicable) in future versions of the BASH and LOCBART codes. A combination of SBLOCTA sensitivity calculations and engineering judgment led to an estimated PCT effect of 0°F for existing Large and Small Break LOCA analysis results.
Treatment of Vessel Averaaqe Temperature Uncertainty Affected Evaluation Model(s): SBLOCA, 1985 NOTRUMP Model, BELOCA 1996 Model Historically, the overall vessel average temperature uncertainty calculated by Westinghouse considered only "-" instrument uncertainties, corresponding to the indicated temperature being lower than the actual temperature. This uncertainty was then applied as a "+/-" uncertainty in some LOCA analyses, rather than using specific "+" and "-" uncertainties. This issue was judged to have a negligible impact on existing Large and Small Break LOCA analysis results, leading to an estimated PCT impact of 0°F.
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Table 2 Peak Cladding Temperature Summary - McGuire Units 1 & 2 and Catawba Unit I LBLOCA Cladding Temp (OF)
Comments Evaluation model: WCOBRA/TRAC, CQD 1996 Analysis of record PCT MNS/CNS 2028 Composite Model Prior errors (APCT)
- 1. Decay heat in Monte Carlo calculations 8
Reference A
- 2. MONTECF power uncertainty correction 20 Reference B
- 3. Safety Injection temperature range 59 Reference C
- 4. Input error resulting in an incomplete solution matrix 25 Reference D
- 5. Revised Blowdown Heatup Uncertainty Distribution 5
Reference E
- 6. Vessel Unheated Conductor Noding 0
Reference F Prior evaluation model changes (APCT)
- 1. Revised Algorithm for Average Fuel Temperature 0
Reference F Errors (APCT)
- 1. None 0
Evaluation model changes (APCT)
- 1. None 0
Absolute value of errors/changes for this report (APCT) 0 Net change in PCT for this report 0
Final PCT 2145 SBLOCA Evaluation model: NOTRUMP Analysis of record PCT 1323 2 inch break Prior errors (APCT)
- 1. None 0
Prior evaluation model changes (APCT)
- 1. None 0
Errors (APCT)
- 1. None 0
Evaluation model changes (APCT)
- 1. None 0
Absolute value of errors/changes for this report (APCT) 0 Net change in PCT for this report 0
Final PCT 1323
Reference:
A) Letter, M. S. Tuckman (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," May 3, 2001 (ML011310391)
B) Letter, M. S. Tuckman (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," April 3, 2002 (ML021070656)
C) Letter, W. R. McCollum, Jr. (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," July 29, 2003 (ML032170639)
D) Letter, W. R. McCollum, Jr. (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," May 26, 2004 (ML041560349)
E) Letter, J. R. Morris (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," June 21, 2005 (ML051790210)
F) Letter, T. C. Geer (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," March 13, 2007 (ML070800546)
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Table 3 Peak Cladding Temperature Summary - Catawba Unit 2 LBLOCA Cladding Temp (OF)
Comments Evaluation model: WCOBRA/TRAC, CQD 1996 MNS/CNS Analysis of record PCT 2028 Composite Model Prior errors (APCT)
- 1. Decay heat in Monte Carlo calculations 8
Reference A
- 2. MONTECF power uncertainty correction 20 Reference B
- 3. Safety Injection temperature range 59 Reference C
- 4. Input error resulting in an incomplete solution matrix 25 Reference D
- 5. Revised Blowdown Heatup Uncertainty Distribution 5
Reference E
- 6. Vessel Unheated Conductor Noding 0
Reference F Prior evaluation model changes (APCT)
- 1. Revised Algorithm for Average Fuel Temperature 0
Reference F Errors (APCT)
- 1. None 0
Evaluation model changes (APCT)
- 1. None 0
Absolute value of errors/changes for this report (APCT) 0 Net change in PCT for this report 0
Final PCT 2145 SBLOCA Evaluation model: NOTRUMP Analysis of record PCT 1243 4 inch break Prior errors (APCT)
- 1. None 0
Prior evaluation model changes (APCT)
- 1. None 0
Errors (APCT)
- 1. None 0
Evaluation model changes (APCT)
- 1. None 0
Absolute value of errors/changes for this report (APCT) 0 Net change in PCT for this report 0
Final PCT 1243
Reference:
A) Letter, M. S. Tuckman (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," May 3, 2001 (ML011310391)
B) Letter, M. S. Tuckman (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," April 3, 2002 (ML021070656)
C) Letter, W. R. McCollum, Jr. (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," July 29, 2003 (ML032170639)
D) Letter, W. R. McCollum, Jr. (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," May 26, 2004 (ML041560349)
E) Letter, J. R. Morris (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," June 21, 2005 (ML051790210)
F) Letter, T. C. Geer (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," March 13, 2007 (ML070800546)
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