ML051790210
| ML051790210 | |
| Person / Time | |
|---|---|
| Site: | Mcguire, Catawba, McGuire  |
| Issue date: | 06/21/2005 |
| From: | Morris J Duke Energy Corp |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML051790210 (8) | |
Text
JAMES R MORRIS
_ Duke Vice President, Nuclear Support OrPowere Nuclear Generation Duke Power 526 South Church St.
Charlotte, NC 28202 June 21, 2005 Mailing Address.
EC07H / PO Box 1006 U. S. Nuclear Regulatory Commission Charlotte, NC 28201-1006 Washington, D. C. 20555-001 704 382 6401 Attention: Document Control Desk 704 382 6056 fax james. morris@duke-energy.com
Subject:
Duke Energy Corporation 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, 2004 to December 31, 2004.
During this time period, one error correction was identified in the Westinghouse large break LOCA analyses which had a peak cladding temperature (PCT) impact. This correction is not classified as significant per the 10 CFR 50.46 criterion. A revision to the blowdown heat transfer coefficients was developed and implemented. This correction resulted in a change in the overall code uncertainty for the blowdown phase of the event. A plant specific estimate of the impact of this change was determined to be 5 "F. Details of this correction are presented in Table 1.
Two enhancements were made to the large break LOCA (LBLOCA) evaluation model in 2004. These changes were not considered to have any impact on the LBLOCA calculated PCTs. The specifics of these enhancements are provided in Table 2. Since there was no PCT impact determined for these changes, they are not included in the PCT summary tables.
In 2004, McGuire Unit 1 was loaded with a core comprised entirely of Westinghouse Robust Fuel Assembly (RFA) fuel (i.e., no Framatome fuel). Thus, the mixed core penalty applied to the SBLOCA peak cladding temperature (PCT) is removed for that unit. All other units operated in 2004 with some Framatome fuel and therefore, the mixed core penalty is retained for these units.
A summary of the peak cladding temperatures for McGuire Units 1 and 2 is provided in Table 3. Tables 4 and 5 provide a summary of the peak cladding temperatures for Catawba Units 1 and 2 respectively.
ADC) www. dukepower. corn
U.S. Nuclear Regulatory Commission June 21, 2005 Page 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.
Very truly yours, James R. Morris Attachments Table 1 - Errors/Evaluation Model Changes with PCT Impact Table 2 - Errors/Evaluation Model Changes with no PCT Impact Table 3 - Peak Cladding Temperature Summary - McGuire Units 1 and 2 Table 4 - Peak Cladding Temperature Summary - Catawba Unit 1 Table 5 - Peak Cladding Temperature Summary - Catawba Unit 2 xc: (with attachments)
W. D. Travers, Region II Administrator U.S. Nuclear Regulatory Commission Sam Nunn Atlanta Federal Center, 23 T85 61 Forsyth St., SW Atlanta, GA 30303-8931 S. E. Peters, 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 E. F. Guthrie, NRC Senior Resident Inspector Catawba Nuclear Station
ATTACHMENTS Table 1 - Errors / Evaluation Model Changes with PCT Impact Table 2-Errors/Evaluation Model Changes with no PCT Impact Table 3 - Peak Cladding Temperature Summary - McGuire Units 1 and 2 Table 4 - Peak Cladding Temperature Summary - Catawba Unit 1 Table 5 - Peak Cladding Temperature Summary - Catawba Unit 2
Table 1 Errors / Evaluation Model Changes with PCT Impact Revised Blowdown Heatup Uncertainty Distribution (WCOBRA/TRAC Model)
Revised blowdown phase heatup heat transfer coefficients were developed based on analyses of the LOFT and ORNL test using the latest version of WCOBRA/TRAC. Using these heat transfer coefficients, a revised cumulative distribution function (CDF) was programmed into a new version of HOTSPOT. The overall code uncertainty for the blowdown phase was also recalculated and programmed into a new version of MONTECF. The overall code uncertainty for the reflood phase is not affected. An estimate of the PCT effect of the revised blowdown phase heatup CDF was performed. The estimates bound all of the 9 5th percentile HOTSPOT results. Plant specific MONTECF analysis was performed to estimate the effect of the revised overall code uncertainty for the blowdown phase. For the McGuire/Catawba large break LOCA analysis the PCT impact was estimated to be 5 OF.
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Table 2 Errors / Evaluation Model Changes with no PCT Impact Implementation of ASTRUM Capability in HOTSPOT (WCOBRA/TRAC Model)
The HOTSPOT code was modified to be compatible with the Automated Statistical Treatment of Uncertainty Methodology (ASTRUM) described in WCAP-1 6009-PA. An option was added to allow the ASTRUM HOTSPOT technique (single iteration mode) instead of the Monte Carlo mode that is used in the previous Best Estimate LBLOCA evaluation models. This change does not affect the results of design basis analyses performed with the previous evaluation models. Therefore, the PCT is unaffected by this change.
Improved Automation of End of Blowdown Time (WCOBRAITRAC Model)
An automated end of blowdown selection logic was added to large break LOCA analysis method.
The new end of blowdown selection is based on the time at which the system pressure stops decreasing. In the current method, the end of blowdown was chosen to be the time the system pressure dropped below 40 psia. For cases where the pressure did not drop below 40 psia, the analyst would manually redefine the end of blowdown. Blowdown cooling heat transfer multipliers are applied during the later period of the blowdown phase. These heat transfer multipliers are considered in the uncertainty methodology as a function of the time period in the transient. All prior analyses used the correct end of blowdown time and therefore are not impacted by this change.
Therefore, the estimated PCT impact of this change is zero.
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Table 3 Peak Cladding Temperature Summary - McGuire Units 1 & 2 LBLOCA Cladding Temp (OF)
Comments Evaluation model: WCOBRNTRAC_
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 Prior evaluation model changes (APCT)
- 1. None 0
Errors (APCT)
- 1. Revised Blowdown Heatup Uncertainty Distribution 5
Evaluation model changes (APCT)
- 1. None 0
Absolute value of errors/changes for this report (APCT) 5 Net change in PCT for this report 5
Final PCT 2145 SBLOCA Evaluation model: NOTRUMP MNS-1 / MNS-2 Analysis of record PCT 1167 /1177 Note (1)
Prior errors (APCT)
- 1. Mixture level tracking/region depletion 13 Reference A
- 2. NOTRUMP bubble rise/drift flux model corrections 35 Reference D 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 1215 /1225
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 Note:
(1) The analysis of record PCT for MNS-2 includes a 10 OF allowance for the presence of FANP fuel.
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Table 4 Peak Cladding Temperature Summary - Catawba Unit 1 LBLOCA Cladding Temp Comments (OF)
Evaluation model: WCOBRA/TRAC 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 Prior evaluation model changes (APCT)
- 1. None 0
Errors (APCT)
- 1. Revised Blowdown Heatup Uncertainty Distribution 5
Evaluation model changes (APCT)
- 1. None 0
Absolute value of errors/changes for this report (APCT) 5 Net change in PCT for this report 5
Final PCT 2145 SBLOCA Evaluation model: NOTRUMP Analysis of record PCT 1177 Note (1)
Prior errors (APCT)
- 1. Mixture level tracking/region depletion 13 Reference A
- 2. NOTRUMP bubble rise/drift flux model corrections 35 Reference D 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 1225
Reference:
A) letter, G. R. Peterson (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", April 11, 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 Note:
(1) The analysis of record PCT includes a 10 OF allowance for the presence of FANP fuel.
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Table 5 Peak Cladding Temperature Summary - Catawba Unit 2 LBLOCA Cladding Temp Comments (OF)
Evaluation model: WCOBRA/TRAC 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 Prior evaluation model changes (APCT)
- 1. None 0
Errors (APCT)
- 1. Revised Blowdown Heatup Uncertainty Distribution 5
Evaluation model changes (APCT)
- 1. None 0
Absolute value of errors/changes for this report (APCT) 5 Net change in PCT for this report 5
Final PCT 2145 SBLOCA Evaluation model: NOTRUMP Analysis of record PCT 1073 Note (1)
Prior errors (APCT)
- 1. Mixture level tracking/region depletion 13 Reference A
- 2. NOTRUMP bubble rise/drift flux model corrections 35 Reference D 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 1121
Reference:
A) letter, G. R. Peterson (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", April 11, 2001 B) letter, M. S. Tuckman (Duke) to USNRC, uReport 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 Note:
(1) The analysis of record PCT includes a 10 'F allowance for the presence of FANP fuel.
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