DCL-10-080, 10 CFR 50.46 Annual Report of Emergency Core Cooling System Evaluation Model Changes for 2009
| ML102010114 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 07/19/2010 |
| From: | Becker J Pacific Gas & Electric Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| DCL-10-080 | |
| Download: ML102010114 (9) | |
Text
Pacific Gas and Electric Company Diablo Canyon Power Plant James R. Becker Site Vice President Mail Code 104/5/601 .
P. O. Box 56 Avila Beach, CA 93424 805.545.3462 July 19, 2010 Internal: 691.3462 Fax: 805.545.6445 PG&E Letter DCL-10-080 u.s. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 10 CFR 50.46 Annual Report of Emergency Core Cooling System Evaluation Model Changes for 2009
Dear Commissioners and Staff:
Pursuant to 10 CFR 50.46, this letter provides an annual report of changes in the Westinghouse emergency core cooling system (ECCS) evaluation models that affect peak cladding temperature (PCT) calculations for Pacific Gas and Electric Company (PG&E) Diablo Canyon Power Plant (DCPP), Units 1 and 2.
There have been no changes in the small-break loss-of-coolant accident (SBLOCA)
PCT results or the large break best estimate loss of coolant accident (BELOCA) PCT results for either Unit 1 or Unit 2 since the last annual update. The last update was provided in PG&E Letter DCL-09-057, "10 CFR 50.46 Annual Report of Emergency Core Cooling System Evaluation Model Changes for 2008" dated July 31,2009.
A summary of the PCT margin allocations and their bases are provided in the enclosure. The Unit 1 SBLOCA and BELOCA PCT Margin Utilization sheets are provided in Attachment A. The Unit 2 SBLOCA and BELOCA PCT Margin Utilization Sheets are provided in Attachment B. There have been no reportable ECCS evaluation model changes or errors that have occurred since the last annual report as summarized in Attachment C.
The PCT values remain within the 2200°F limit specified in 10 CFR 50.46. However, since the Unit 1 BELOCA has a total PCT margin allocation that is currently greater than 50°F, PG&E is proposing a schedule for reanalysis, per 10 CFR 50.46(a)(3)(ii).
PG&E has recently initiated a long term project to implement 24 month fuel cycles that will require a reanalysis of the Unit 1 BELOCA PCT results. In order to coordinate with the 24 month fuel cycle project schedule, PG&E proposes to complete the Unit 1 BELOCA reanalysis and provide the update PCT results to the NRC by December 2012.
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- South Texas Project
- Wolf Creek
Document Control Desk PG&E Letter DCL-10-080 July 19, 2010 Page 2 If you have questions regarding this submittal please contact Mr. Steve Baker at 805-545-6742.
Site Vice President and Station Director swh/22541A067 4893 Enclosure cc/enc: Elmo E. Collins, NRC Region IV Michael S. Peck, NRC Senior Resident Inspector Alan B. Wang, NRR Project Manager Diablo Distribution A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- South Te x as Project
- Wolf Creek
Enclosure PG&E Letter DCL-10-080 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM EVALUATION MODEL CHANGES FOR PEAK CLADDING TEMPERATURE Pursuant to 10 CFR 50.46, this enclosure provides an annual report of changes in the Westinghouse emergency core cooling system (ECCS) evaluation models that affect peak cladding temperature (PCT) calculations for Pacific Gas and Electric Company (PG&E) Diablo Canyon Power Plant (DCPP), Units 1 and 2.
This report is based on changes described in the following Westinghouse 10 CFR 50.46 notification letter:
Westinghouse Letter LTR-LIS-10-84, Diablo Canyon Units 1 and 2 10 CFR 50.46 Annual Notification and Reporting for 2009, dated February 4, 2010.
Attachment A to this enclosure provides DCPP Unit 1 small-break loss-of-coolant accident (SBLOCA) and best estimate large-break loss of coolant accident (BELOCA) PCT Margin Utilization Sheets. Attachment B to this enclosure provides DCPP Unit 2 SBLOCA and BELOCA PCT Margin Utilization Sheets.
There have been no changes in the small-break loss-of-coolant accident (SBLOCA) PCT results or the large break best estimate loss of coolant accident (BELOCA) PCT results for either Unit 1 or Unit 2 since the last annual update. The last update was provided in PG&E Letter DCL-09-057, 10 CFR 50.46 Annual Report of Emergency Core Cooling System Evaluation Model Changes for 2008 dated July 31, 2009.
The summary of the PCT margin allocations and their bases are provided in the attachments, and the final net PCT values are listed below for each unit. It should be noted that two PCT values are reported for the Unit 1 BELOCA results.
The two BELOCA PCT values are labeled Reflood 1 and Reflood 2, as they represent the two distinctive PCT peaks that occur during the reflood phase for the Unit 1 BELOCA CQD methodology. The Unit 2 BELOCA reports only one PCT value consistent with the BELOCA ASTRUM methodology.
Small-Break LOCA Large-Break Best Estimate LOCA Reflood 1 Reflood 2 Unit 1: 1391F (no change) 1990F (no change) 1936F (no change)
Unit 2: 1288F (no change) 1872F (no change)
These PCT values remain within the 2200F limit specified in 10 CFR 50.46.
There have been no reportable ECCS evaluation model changes or errors that have occurred since the last annual report as summarized in Attachment C.
Since the Unit 1 BELOCA has a total PCT margin allocation that is greater than 50F, per 10 CFR 50.46, PG&E is proposing a schedule for reanalysis. PG&E has recently initiated a long term project to implement 24 month fuel cycles that will require a reanalysis of the Unit 1 BELOCA PCT results. In order to 1
Enclosure PG&E Letter DCL-10-080 coordinate with the 24 month fuel cycle project schedule, PG&E proposes to complete the Unit 1 BELOCA reanalysis and provide the updated PCT results to the NRC by December 2011.
2
Attachment A PG&E Letter DCL-10-080 DCPP UNIT 1 PEAK CLADDING TEMPERATURE MARGIN UTILIZATION SMALL-BREAK LOCA PG&E Letter1 A. ANALYSIS OF RECORD PCT = 1391F DCL-09-057 B. PRIOR 10 CFR 50.46 ECCS MODEL ASSESSMENTS2
- 1. None PCT = 0F C. 10 CFR 50.46 ECCS MODEL ASSESSMENTS THIS YEAR
- 1. None PCT = 0F D. SUM OF 10 CFR 50.46 CHANGES
- 1. Net Sum of 10 CFR 50.46 PCT Changes PCT = 0F
- 2. Absolute Sum of 10 CFR 50.46 PCT Changes PCT = 0F E. Analysis of Record PCT - Line A
+ Line D.1 Net Sum of 10 CFR 1391F 50.46 PCT Changes The sum of the PCT from the most recent analysis of record using an acceptable evaluation model and the estimates of the net PCT effect for changes and errors identified since this analysis remain less than 2200F.
1 For those issues that have been previously reported under 10 CFR 50.46, a PG&E letter number is listed.
2 Only permanent assessments of PCT margin are included. Temporary PCT allocations that address current LOCA model issues are not considered with respect to 10 CFR 50.46 reporting requirements.
A-1
Attachment A PG&E Letter DCL-10-080 DCPP UNIT 1 PEAK CLADDING TEMPERATURE MARGIN UTILIZATION BEST ESTIMATE LARGE-BREAK LOCA PG&E Letter1 Reflood Reflood 1 2 A. ANALYSIS OF RECORD 1900F 1860F DCL-05-146 PCT PCT B. PRIOR 10 CFR 50.46 ECCS MODEL ASSESSMENTS 2
- 1. Revised blowdown heatup 5F 5F DCL-05-086 uncertainty distribution.
- 2. HOTSPOT Fuel Relocation 10F 0F DCL-07-071 Error.
C. 10 CFR 50.46 ECCS MODEL ASSESSMENTS THIS YEAR
- 1. Replacement Steam 75F 71F DCL-09-057 Generators D. SUM OF 10 CFR 50.46 CHANGES
- 1. Net Sum of 10 CFR 50.46 PCT 90F 76F Changes
- 2. Absolute Sum of 10 CFR 50.46 90F 76F PCT Changes E. Analysis of Record PCT - Line A +
Line D.1 Net Sum of 10 CFR 50.46 1990F 1936F PCT Changes The sum of the PCT from the most recent analysis of record using an acceptable evaluation model and the estimates of the net PCT effect for changes and errors identified since this analysis remain less than 2200F.
1 For those issues that have been previously reported under 10 CFR 50.46, a PG&E letter number is listed.
2 Only permanent assessments of PCT margin are included. Temporary PCT allocations that address current LOCA model issues are not considered with respect to 10 CFR 50.46 reporting requirements.
A-2
Attachment B PG&E Letter DCL-10-080 DCPP UNIT 2 PEAK CLADDING TEMPERATURE MARGIN UTILIZATION SMALL-BREAK LOCA PG&E Letter1 A. ANALYSIS OF RECORD PCT = 1288F DCL-08-061 B. PRIOR 10 CFR 50.46 ECCS MODEL ASSESSMENTS2
- 1. None PCT = 0F C. 10 CFR 50.46 ECCS MODEL ASSESSMENTS THIS YEAR
- 2. None PCT = 0F D. SUM OF 10 CFR 50.46 CHANGES
- 3. Net Sum of 10 CFR 50.46 PCT Changes PCT = 0F
- 4. Absolute Sum of 10 CFR 50.46 PCT Changes PCT = 0F E. Analysis of Record PCT - Line A
+ Line D.1 Net Sum of 10 CFR 1288F 50.46 PCT Changes The sum of the PCT from the most recent analysis of record using an acceptable evaluation model and the estimates of the net PCT effect for changes and errors identified since this analysis remain less than 2200F.
1 For those issues that have been previously reported under 10 CFR 50.46, a PG&E Letter number is listed.
2 Only permanent assessments of PCT margin are included. Temporary PCT allocations that address current LOCA model issues are not considered with respect to 10 CFR 50.46 reporting requirements.
B-1
Attachment B PG&E Letter DCL-10-080 DCPP UNIT 2 PEAK CLADDING TEMPERATURE MARGIN UTILIZATION BEST ESTIMATE LARGE-BREAK LOCA PG&E Letter1 A. ANALYSIS OF RECORD PCT= 1872F DCL-07-071 B. PRIOR 10 CFR 50.46 ECCS MODEL ASSESSMENTS 2
- 1. HOTSPOT Fuel Relocation PCT= 0F DCL-07-071 Error.
C. 10 CFR 50.46 ECCS MODEL ASSESSMENTS THIS YEAR
- 1. None PCT= 0F D. SUM OF 10 CFR 50.46 CHANGES
- 1. Net Sum of 10 CFR 50.46 PCT PCT= 0F Changes
- 2. Absolute Sum of 10 CFR 50.46 PCT= 0F PCT Changes E. Analysis of Record PCT - Line A +
Line D.1 Net Sum of 10 CFR 50.46 1872F PCT Changes The sum of the PCT from the most recent analysis of record using an acceptable evaluation model and the estimates of the net PCT effect for changes and errors identified since this analysis remain less than 2200F.
1 For those issues that have been previously reported under 10 CFR 50.46, a PG&E letter number is listed.
2 Only permanent assessments of PCT margin are included. Temporary PCT allocations that address current LOCA model issues are not considered with respect to 10 CFR 50.46 reporting requirements.
B-2
Attachment C PG&E Letter DCL-10-080 CURRENT EMERGENCY CORE COOLING SYSTEM MODEL CHANGES AND ERRORS There have been no reportable ECCS evaluation model changes or errors that have occurred since the last annual report.
C -1