DCL-18-071, 10 CFR 50.46 Annual Report of Emergency Core Cooling System Evaluation Model Changes for Peak Cladding Temperature for 2017

10 CFR 50.46 Annual Report of Emergency Core Cooling System Evaluation Model Changes for Peak Cladding Temperature for 2017

ML18268A368
Person / Time
Site:	Diablo Canyon
Issue date:	09/25/2018
From:	Welsch J Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-18-071
Download: ML18268A368 (8)

Text

Pacific Gas and Electric Company" James M. Welsch Diablo Canyon Power Plant Vice President P.O. Box 56 Nuclear Generation and Avila Beach, CA 93424 Chief Nuclear Officer 805.545.3242 E-Mail: James.Welsch@pge.com September 25, 2018 PG&E Letter DCL-18-071 U.S. Nuclear Regulatory Commission 10 CFR 50.46 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 Peak Cladding Temperature for 2017

Dear Commissioners and Staff:

Pursuant to 10 CFR 50.46, Pacific Gas and Electric Company (PG&E) hereby submits the annual report of changes in the Westinghouse emergency core cooling system evaluation models that affect peak cladding temperature (PCT) calculations for Diablo Canyon Power Plant, Units 1 and 2.

The enclosure and its attachments provide a summary of the PCT margin allocations and their bases.

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 remains within the 2200°F limit specified in 10 CFR 50.46.

PG&E makes no new or revised regulatory commitments (as defined by NEI 99-04) in this letter.

If you have questions regarding this submittal please contact Mr. Mark Sharp at 805-545-3031.

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• Diablo Canyon

• Palo Verde

• Wolf Creek

Document Control Desk PG&E Letter DCL-18-071 September 25, 2018 Page2 dqmg/6192/50871345 Enclosure cc: Diablo Distribution cc/enc: Kriss M. Kennedy, NRC Region IV Administrator Christopher W. Newport, NRC Senior Resident Inspector Balwant K. Singal, NRC Senior Project Manager A member of the STARS Alliance Calla w ay

• Diablo Cany o n

• Palo Verde

• Wolf Cree k

Enclosure PG&E Letter DCL-18-071 ANNUAL REPORT OF EMERGENCY CORE COOLING SYSTEM EVALUATION MODEL CHANGES FOR PEAK CLADDING TEMPERATURE

Enclosure PG&E Letter DCL-18-071 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 evaluation models that affect peak cladding temperature (PCT) calculations for Pacific Gas and Electric Company's Diablo Canyon Power Plant, Units 1 and 2. This report is based on changes described in Westinghouse Letter LTR-LIS-18-17, "Diablo Canyon Units 1 and 2 10 CFR 50.46 Annual Notification and Reporting for 2017," dated February 15, 2018.

Attachment A contains 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 contains the corresponding Unit 2 data. There have been no changes in the SBLOCA PCT results or BELOCA PCT results for either Unit 1 or Unit 2 since the previous annual update.

The final net PCT values are listed below for each unit. 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 Code Qualification Document methodology. The Unit 2 BELOCA reports only one PCT value consistent with the BELOCA ASTRUM methodology.

Unit SBLOCA BELOCA Unit 1 1391 °F (no change) Reflood 1 Reflood 2 2049°F (no change) 2124°F (no change)

Unit 2 1288°F (no change) 2125°F (no change)

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 remains within the 2200°F limit specified in 10 CFR 50.46.

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Enclosure Attachment A PG&E Letter DCL-18-071 DIABLO CANYON POWER PLANT, UNIT 1 PEAK CLADDING TEMPERATURE MARGIN UTILIZATION SMALL-BREAK PG&E Letter1 LOSS-OF-COOLANT-ACCIDENT (LOCA}

Peak Cladding A. ANALYSIS OF RECORD 1391 °F DCL-09-057 Temperature (PCT)=

B. PRIOR 10 CFR 50.46 EMERGENCY CORE COOLING SYSTEM (ECCS)

MODEL ASSESSMENTS

1. None .".\PCT= 0°F C. 10 CFR 50.46 ECCS MODEL ASSESSMENTS THIS YEAR

1. None .".\PCT= 0°F D. SUM OF 10 CFR 50.46 CHANGES

1. Net Sum of 10 CFR 50.46 PCT Changes .".\PCT= 0°F

2. Absolute Sum of 10 CFR 50.46 PCT

.".\PCT= 0°F Changes E. Analysis of Record PCT (Line A) + Line D.1 Net Sum 1391 °F of 10 CFR 50.46 PCT Changes For those issues that have been previously reported under 10 CFR 50.46, a PG&E letter number is listed .

A-1

Enclosure Attachment A PG&E Letter DCL-18-071 DIABLO CANYON POWER PLANT, UNIT 1 PEAK CLADDING TEMPERATURE MARGIN UTILIZATION BEST-ESTIMATE, LARGE-BREAK LOCA PG&E Letter1 Reflood 1 Reflood 2 A. ANALYSIS OF RECORD 1900°F 1860°F DCL-05-146

~PCT ~PCT B. PRIOR 10 CFR 50.46 ECCS MODEL ASSESSMENTS

1. Revised blowdown heatup 5°F 5°F DCL-05-086 uncertainty distribution.

2. HOTSPOT Fuel Relocation 10°F 0°F DCL-07-071 Error.

3. Replacement Steam 75°F 71°F DCL-09-057 Generators

4. 230 kV Degraded Voltage Event 0°F 39°F DCL-11-082

5. Performance and Design 4.0 -118°F -118°F DCL-12-102 Implementation

6. Fuel Thermal Conductivity 133°F 238°F DCL-12-102 Degradation and Peaking Factor Burndown

7. Revised Heat Transfer Multiplier 5°F -35°F DCL-13-111 Distributions

8. Changes to Grid Blockage and 24°F 24°F DCL-13-111 Porosity

9. Error in Burst Strain Application 15°F 40°F DCL-14-070 C. 10 CFR 50.46 ECCS MODEL ASSESSMENTS THIS YEAR

1. None 0°F 0°F D. SUM OF 10 CFR 50.46 CHANGES

1. Net Sum of PCT Changes 149°F 264°F

2. Absolute Sum of PCT Changes 385°F 570°F E. Analysis of Record PCT (Line A) +

Line D.1 Net Sum of 10 CFR 50.46 2049°F 2124°F PCT Changes For those issues that have been previously reported under 10 CFR 50.46, a PG&E letter number is listed.

A-2

Enclosure Attachment B PG&E Letter DCL-18-071 DCPP UNIT 2 PEAK CLADDING TEMPERATURE MARGIN UTILIZATION SMALL-BREAK LOSS-OF-COOLANT ACCIDENT (LOCA) PG&E Letter1 Peak Cladding A. ANALYSIS OF RECORD 1288°F DCL-08-061 Temperature (PCT)=

B. PRIOR 10 CFR 50.46 EMERGENCY CORE COOLING SYSTEM(ECCS)MODEL ASSESSMENTS

1. None LiPCT = 0°F C. 10 CFR 50.46 ECCS MODEL ASSESSMENTS THIS YEAR

1. None LiPCT = 0°F D. SUM OF 10 CFR 50.46 CHANGES

1. Net Sum of 10 CFR 50.46 PCT Changes LiPCT = 0°F

2. Absolute Sum of 10 CFR 50.46 PCT Changes LiPCT = 0°F E. Analysis of Record PCT (Line A) +

Line D.1 Net Sum of 10 CFR 50.46 1288°F PCT Changes For those issues that have been previously reported under 10 CFR 50.46, a PG&E Letter number is listed.

B-1

Enclosure Attachment B PG&E Letter DCL-18-071 DCPP UNIT 2 PEAK CLADDING TEMPERATURE MARGIN UTILIZATION BEST-ESTIMATE, LARGE BREAK LOCA PG&E Letter1 A. ANALYSIS OF RECORD PCT= 1872°F DCL-07-071 B. PRIOR 10 CFR 50.46 ECCS MODEL ASSESSMENTS

1. HOTSPOT Fuel Relocation Error. ~PCT= 0°F DCL-07-071

2. 230 kV Degraded Voltage Event. ~PCT= 16F DCL-11-082

3. Fuel Thermal Conductivity Degradation and Peaking Factor ~PCT= 209°F DCL-12-102 Burndown

4. Revised Heat Transfer Multiplier

~PCT= -17°F DCL-13-111 Distribution

5. Changes to Grid Blockage and

~PCT= 24°F DCL-13-111 Porosity

6. Error in Burst Strain Application ~PCT= 21 °F DCL-14-070 C. 10 CFR 50.46 ECCS MODEL ASSESSMENTS THIS YEAR

1. None ~PCT= 0°F D. SUM OF 10 CFR 50.46 CHANGES

1. Net Sum of 10 CFR 50.46 PCT

~PCT= 253°F Changes

2. Absolute Sum of 10 CFR 50.46

~PCT= 287°F PCT Changes E. Analysis of Record PCT (Line A) +

Line 0.1 Net Sum of 10 CFR 50.46 2125°F PCT Changes For those issues that have been previously reported under 10 CFR 50.46, a PG&E letter number is listed.

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