ML092180407

Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model

ML092180407
Person / Time
Site:	Mcguire, Catawba, McGuire
Issue date:	08/03/2009
From:	Geer T Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML092180407 (6)

Text

THOMAS C. GEER Vice President fEnergy.

Nuclear Engineering Duke Energy Corporation 526 South Church St.

Charlotte, NC 28202 August 3, 2009 Mailing Address:

EC08H / PO Box 1006 Charlotte, NC 28201-1006 U. S. Nuclear Regulatory Commission 704 382 4712 Washington, D. C. 20555-001 704 382 7852 fax Attention: Document Control Desk tcgeer@duke-energy. corn

Subject:

Duke Energy Carolinas, LLC (Duke)

McGuire Nuclear Station, Units 1 and 2 Docket Number 50-369 and 50-370 Catawba Nuclear Station, Units 1 and 2 Docket Number 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 errors or changes in the Emergency Core Cooling System (ECCS) evaluation models. This report covers the time period from January 1, 2008 to December 31, 2008. 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, one non-discretionary change was made to the large break loss of coolant accident (LBLOCA) evaluation model, and two non-discretionary changes were made to the small break LOCA (SBLOCA) evaluation model. 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 of a number of discretionary coding changes that were made as part of normal code maintenance and general code cleanup for both the LBLOCA and SBLOCA 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 also not included in the PCT summary tables.

Except for the MOX lead assemblies that operated in Catawba Unit 1 during the first half of calendar year 2008, all McGuire and Catawba units were loaded with a core comprised entirely of Westinghouse fuel during this time reporting period. Therefore, no transition core PCT penalties are included in the PCT summary tables.

74b D2 www.duke-energy.com*

U.S. Nuclear Regulatory Commission August 3, 2009 Page 2 A summary of the PCT changes for McGuire Units 1 and 2 and Catawba Unit 1 is provided in Table 2, and Table 3 provides a summary of the PCT changes for Catawba Unit 2.

There are no regulatory commitments associated with this letter.

Please address any comments or questions regarding this matter to L. B. Jones at (704) 382-4753.

Sincerely, Thomas C. Geer Vice President, Nuclear Engineering Attachments Table 1 - Errors/Evaluation Model Changes with no PCT Impact Table 2 - Peak Cladding Temperature Summary - McGuire Units 1 & 2 and Catawba Unit 1 Table 3 - Peak Cladding Temperature Summary - Catawba Unit 2 xc: (with attachments)

L. A. Reyes, Region II Administrator U.S. Nuclear Regulatory Commission Sam Nunn Atlanta Federal Center, 23 T85 61 Forsyth St., SW Atlanta, GA 30303-8931 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. B. Brady, NRC Senior Resident Inspector McGuire Nuclear Station G. A. Hutto, 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 1 & 2 and Catawba Unit I Table 3 - Peak Cladding Temperature Summary - Catawba Unit 2 Page 1

Table 1 Errors / Evaluation Model Changes with no PCT Impact Discretionary Changes:

General Code Maintenance (NOTRUMP Model)

These changes (i.e., modifying variable input definitions, units, and defaults; eliminating inactive coding; optimizing active coding; improving input diagnostic checks; and enhancing code output) enhance code usability to help preclude errors in future analyses.

General Code Maintenance (BELOCA 1996 Model)

These changes (i.e., additional information in code outputs, improved automation and diagnostics in the codes, increased code dimensions) were made as part of general code maintenance and cleanup.

Non-Discretionary Changes:

HOTSPOT Burst Temperature Logic Errors (BELOCA 1996 Model)

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 few than five values are available, and (3) reflect the assumed saturation of ramp rate effects above 28 degrees Celsius per second for Zircaloy-4 cladding from Equation 7-66 of WCAP-12945-P-A, Volume 1 (Revision 2) and Volumes 2-5 (Revision 1), "Code Qualification Document for Best Estimate LOCA Analysis." Sample calculations showed no effect on PCT, leading to an estimated PCT impact of zero for 10 CFR 50.46 reporting purposes.

Errors in Reactor Vessel Lower Plenum Surface Area Calculations (NOTRUMP Model)

Two errors were discovered in the calculations of the reactor vessel lower plenum surface area.

The differences are relatively minor and have been evaluated for impact on the current licensing-basis analysis results, leading to an estimated PCT impact of zero for 10 CFR 50.46 reporting purposes.

Discrepancy in Metal Masses Used from Drawings (NOTRUMP Model)

Discrepancies were discovered in the use of metal masses from drawings. The differences are relatively minor and have been evaluated for impact on the current licensing-basis analysis results, leading to an estimated PCT impact of zero for 10 CFR 50.46 reporting purposes.

Page 2

Table 2 Peak Cladding Temperature Summary - McGuire Units 1 & 2 and Catawba Unit 1 LBLOCA Cladding Temp (IF)

Comments Evaluation model: BELOCA 1996 MNS/CNS Analysis of record PCT 2028 Composite Model Prior errors (APCT) 11ý. 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 Reference G 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) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", May 3, 2001 B) letter, M. S. Tuckman (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", April 3, 2002 C) letter, W. R. McCollum, Jr. (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", July 29, 2003 D) letter, W. R. McCollum, Jr. (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", May 26, 2004 E) letter, J. R. Morris (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", June 21, 2005 F) letter, T. C. Geer (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", March 13, 2007 G) letter, T. C. Geer (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", May 22, 2007 Page 3

Table 3 Peak Cladding Temperature Summary - Catawba Unit 2 LBLOCA Cladding Temp (OF)

Comments Evaluation model: BELOCA 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 Reference G 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) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", May 3, 2001 B) letter, M. S. Tuckman (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", April 3, 2002 C) letter, W. R. McCollum, Jr. (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", July 29, 2003 D) letter, W. R. McCollum, Jr. (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", May 26, 2004 E) letter, J. R. Morris (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", June 21, 2005 F) letter, T. C. Geer (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", March 13, 2007 G) letter, T. C. Geer (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", May 22, 2007 Page 4