ML12310A058
| ML12310A058 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 10/18/2012 |
| From: | Flores R Luminant Generation Co, Luminant Power |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CP-21201172, TXX-12146 | |
| Download: ML12310A058 (9) | |
Text
Rafael Flores Luminant Power B Senior Vice President
& Chief Nuclear Officer rafael.flores@Luminant.com P 0 Box 1002 6322 North FM 56 Glen Rose, TX 76043 Luminant T 254 897 5550 C 817 559 0403 F 254 897 6652 REF: 10CFR50.46(a)(3) (ii)
CP- 201201172 TXX-12146 October 18, 2012 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
SUBJECT:
COMANCHE PEAK NUCLEAR POWER PLANT (CPNPP)
DOCKET NOS. 50-445 AND 50-446 30-DAY REPORT FOR SIGINIFICANT CHANGE IN PEAK CLAD TEMPERATURE
REFERENCES:
- 1. WCAP-16009-P-A, "Realistic Large-Break LOCA Evaluation Methodology Using the Automated Statistical Treatment Of Uncertainty Method (ASTRUM)," January 2005.
- 2. WCAP-16762-P, Revision 1, "Best-Estimate Analysis of the Large-Break Loss-of-Coolant Accident for the Comanche Peak Nuclear Power Plant Unit 1 Using the ASTRUM Methodology,"
March 2009.
- 3. WCAP-16763-P, Revision 1, "Best-Estimate Analysis of the Large-Break Loss-of-Coolant Accident for the Comanche Peak Nuclear Power Plant Unit 2 Using the ASTRUM Methodology,"
March 2009.
- 4. WCAP-15063-P-A, Revision 1 with Errata, "Westinghouse Improved Performance Analysis and Design Model (PAD 4.0)," July 2000.
5 WCAP-15064, "Westinghouse Improved Performance Analysis and Design Model (PAD 4.0)," July 1998.
Dear Sir or Madam:
In accordance with 10 CFR 50.46(a)(3)(ii), Luminant Generation Company LLC (Luminant Power) hereby submits information regarding an evaluation of fuel pellet thermal conductivity (TCD) with fuel bumup in the Westinghouse Best Estimate Large Break Loss of Coolant Accident (LBLOCA) analysis methodology for Comanche Peak Nuclear Power Plant (CPNPP) Units 1 and 2 and its effect on peak cladding temperature (PCT). CPNPP Units 1 and 2 use the Westinghouse Automated Statistical Treatment of Uncertainty Method (ASTRUM) Large Break Loss of Coolant Accident (LBLOCA) evaluation methodology (EM) of WCAP-16009-P-A (Reference 1). The ASTRUM methodology application for CPNPP Units 1 and 2 is described in Westinghouse topical reports WCAP-16762-P-A (Reference 2) and WCAP 16763-P-A (Reference 3), respectively.
U. S. Nuclear Regulatory Commission TXX-12146 Page 2 10/18/Z012 documents 10 CFR 50.46 reporting text and the estimated PCT effect of fuel pellet TCD and peaking factor burndown for CPNPP Units I and 2. The peaking factor burndown used in the TCD evaluation is conservative for current cycles and will be added to the Reload Safety Analysis Checklist for validation as part of the reload design process. Revised LBLOCA PCT margin utilization sheets that include PCT estimates for both effects are included in Attachment 1.
To summarize the information in Attachment 1, the calculated PCT for the LBLOCA analyses is changed by:
CPNPP Unit 1 - +1220 F for fuel pellet TCD and peaking factor burndown.
CPNPP Unit 2 - +190°F for fuel pellet TCD and peaking factor burndown.
When considering the effects of fuel pellet TCD and peaking factor burndown, CPNPP Units 1 and 2 continue to demonstrate compliancewith 10 CFR 50.46(b)(1).
The evaluation of fuel pellet TCD represents a significant change in PCT as defined in 10 CFR
- 50. 4 6(a)(3)(i) since the magnitude of the change in PCT is greater than 50'F for CPNPP Units I and 2. 10 CFR 50.46(a)(3)(ii) requires the licensee to provide a report within 30 days, including a proposed schedule for providing a reanalysis or taking other action as may be needed to show compliance with 10 CFR 50.46. Luminant Power has reviewed the information provided by Westinghouse and determined that the adjusted LBLOCA PCT values and the manner in which they were derived continue to comply with the requirements of 10 CFR 50.46. Luminant Power has evaluated the requirement for reanalysis specified in 10 CFR 50.46(a)(3)(ii) and hereby proposes the following schedule for reanalysis.
Before June 15, 2017, Luminant Power will submit to the NRC, for review and approval, a LBLOCA analysis that applies NRC-approved methods that include the effects of fuel pellet TCD. The date for the analysis submittal is based on the following milestones, which must be completed in order to perform a revised licensing basis LBLOCA analysis with an NRC-approved Emergency Core Cooling System Evaluation Model (ECCS EM) that explicitly accounts for TCD:
- 1) NRC approval of a fuel performance analysis methodology that includes the effects of TCD.
The new methodology for developing inputs to the LBLOCA EM would replace the current CPNPP licensing basis methodology in WCAP-15063-P-A, Revision 1 (Reference 4) and WCAP-15064 (Reference 5), which is referenced in Section 4.2 of the CPNPP Final Safety Analysis Report (FSAR).
- 2) NRC approval of a LBLOCA EM that includes the effects of TCD and accommodates the ongoing 10 CFR 50.46(c) rulemaking process. The new methodology would replace the current licensing basis analysis methodology in WCAP-16009-P-A (Reference 1), which is referenced in Section 15.6 of the CPNPP FSAR.
This information satisfies the 30-day reporting requirements of 10 CFR 50.46(a)(3)(ii) for CPNPP Units 1 and 2.
U. S. Nuclear Regulatory Commission TXX-12146 Page 3 10/18/2012 This communication contains the following new licensing basis commitments regarding Comanche Peak Units 1 and 2..-
Commitment No. Commitment Description 4496945 The peaking factor bumdown used in the fuel pellet thermal conductivity evaluation will be added to the Reload Safety Analysis Checklist for validation as part of the reload design process.
4496966 Luminant Power will submit to the NRC, for review and approval, a LBLOCA analysis that applies NRC-approved methods that include the effects of fuel pellet thermal conductivity.
Should you have any questions, please contact J. D. Seawright at (254) 897-0140.
Sincerely, Luminant Generation Company LLC Rafael Flores By: 4
/FredW. Madden Director, Oversight & Regulatory Affairs Attachments - 1. Unit 1 Westinghouse LOCA Peak Clad Temperature Summary for ASTRUM Best Estimate Large Break
- 2. Unit 2 Westinghouse LOCA Peak Clad Temperature Summary for ASTRUM Best Estimate Large Break c- E. E. Collins, Region IV B. K. Singal, NRR Resident Inspectors, Comanche Peak to TXX-12146 Page 1 of 3 Unit 1 Westinghouse LOCA Peak Clad Temperature Summary for ASTRUM Best Estimate Large Break Evaluation of Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown
Background
Fuel pellet thermal conductivity degradation (TCD) and peaking factor burndown were not explicitly considered in the Comanche Peak Unit 1 Best Estimate Large Break Loss-of-Coolant Accident (BE LBLOCA) Analysis of Record (AOR). Nuclear Regulatory Commission (NRC) Information Notice 2011-21 (Reference 1) notified addressees of recent information obtained concerning the impact of irradiation on fuel thermal conductivity and its potential to cause significantly higher predicted peak cladding temperature (PCT) results in realistic emergency core cooling system (ECCS) evaluation models. This evaluation provides an estimated effect of fuel pellet TCD and peaking factor burndown on the PCT calculation for the Comanche Peak Unit 1 BE LBLOCA AOR. This change represents a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451 (Reference 2).
Affected Evaluation Model 2004 Westinghouse Realistic Large Break LOCA Evaluation Model Using ASTRUM.
Estimated Effect A quantitative evaluation, as discussed in Reference 3, was performed to assess the PCT effect of fuel pellet TCD and peaking factor burndown on the Comanche Peak Unit 1 BE LBLOCA analysis and concluded that the estimated PCT impact is 122°F for 10 CFR 50.46 reporting purposes. The peaking factor burndown included in the evaluation is provided in Table 1 is conservative for the current cycle.
Luminant Power and its vendor, Westinghouse Electric Company LLC, utilize processes which ensure that the LOCA analysis input values conservatively bound the as-operated plant values for those parameters and will be validated as part of the reload design process.
Table 1: Peaking Factors Assumed in the Evaluation of TCD Rod Burnup FdH (1),(2) FQ Transient (1) FQ Steady-State (MWd/MTU) _ _ _ _ _ _ _ _ _ _ _ _
0 1.600 2.500 2.000 30,000 1.600 2.500 2.000 60,000 1.400 1.875 1.500 62,000 1.400 1.875 1.500 (1) Includes uncertainties.
(2) Hot assembly average power follows the same bumdown, since it is a function of FdH.
References
- 1. NRC Information Notice 2011-21, McGinty, T. J., and Dudes, L. A., "Realistic Emergency Core Cooling System Evaluation Model Effects Resulting From Nuclear Fuel Thermal Conductivity Degradation," December 13, 2011. (NRC ADAMS # ML113430785)
- 2. WCAP-13451, "Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting,"
October 1992.
- 3. OG-12-386, "For Information Only - Input Supporting the PWROG LBLOCA Program Regarding Nuclear Fuel Thermal Conductivity Degradation (PA-ASC-1073, Revision 0)
(Proprietary/ Non-Proprietary)," September 18, 2012.
to TXX-12146 Page 2 of 3 Plant Name: Comanche Peak Unit 1 Utility Name: Luminant Revision Date: 9/20/2012 Analysis Information EM: ASTRUM (2004) Analysis Date: 7/27/2007 Limiting Break Size: Guillotine FQ: 2.5 FdH: 1.6 Fuel: OFA SGTP (0): 10 Notes:
Clad Temp (OF) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 1492 1 PCT ASSESSMENTS (Delta PCT)
A. PRIOR ECCS MODEL ASSESSMENTS
- 1. None 0 B. PLANNED PLANT MODIFICATION EVALUATIONS 0
- 1. None C. 2012 ECCS MODEL ASSESSMENTS 1 . Evaluation of Fuel Pellet Thermal Conductivity 122 2 (a)
Degradation and Peaking Factor Burndown D. OTHER
References:
- 1. WCAP-16763-P, Revision 1, "Best-Estimate Analysis of the Large-Break Loss-of-Coolant Accident for the Comanche Peak Nuclear Power Plant Unit I Using the ASTRUM Methodology," March 2009.
- 2. LTR-LIS-12-410, "Comanche Peak Units I and 2, 10 CFR 50.46 Notification and Reporting for Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Bumdown," September 20, 2012.
Notes:
(a) This evaluation credits peaking factor burndown, see Reference 2.
to TXX-12146 Page 3 of 3 Plant Name: Comanche Peak Unit I Cycle 16 Utility Name: Luminant Revision Date: 9/20/2012 Analysis Information EM: ASTRUM (2004) Analysis Date: 7/27/2007 Limiting Break Size: Guillotine FQ. 2.5 FdH: 1.6 Fuel: OFA SGTP (%): 10 Notes:
Clad Temp (0 F) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 1492 1 PCT ASSESSMENTS (Delta PCT)
A. PRIOR ECCS MODEL ASSESSMENTS
- 1. None 0 B. PLANNED PLANT MODIFICATION EVALUATIONS 0 2
- 1. PBOT/PMID Violation C. 2012 ECCS MODEL ASSESSMENTS 1 . Evaluation of Fuel Pellet Thermal Conductivity 122 3 (a)
Degradation and Peaking Factor Burndown D. OTHER
References:
- 1. WCAP-16762-P, Revision 1, "Best-Estimate Analysis of the Large-Break Loss-of-Coolant Accident for the Comanche Peak Nuclear Power Plant Unit 1 Using the ASTRUM Methodology," March 2009.
- 2. LTR-LIS-11-490, "10 CFR 50.46 Reporting Text for Comanche Peak Unit 1 Cycle 16 PBOT/PMID Violation Evaluation and Revised PCT Rackup Sheets," September 2011.
- 3. LTR-LIS-12-410, "Comanche Peak Units 1 and 2, 10 CFR 50.46 Notification and Reporting for Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown," September 20, 2012.
Notes:
(a) This evaluation credits peaking factor burndown, see Reference 3.
to TXX-12146 Page 1 of 3 Unit 2 Westinghouse LOCA Peak Clad Temperature Summary for ASTRUM Best Estimate Large Break Evaluation of Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown
Background
Fuel pellet thermal conductivity degradation (TCD) and peaking factor burndown were not explicitly considered in the Comanche Peak Unit 2 Best Estimate Large Break Loss-of-Coolant Accident (BE LBLOCA) Analysis of Record (AOR). Nuclear Regulatory Commission (NRC) Information Notice 2011-21 (Reference 1) notified addressees of recent information obtained concerning the impact of irradiation on fuel thermal conductivity and its potential to cause significantly higher predicted peak cladding temperature (PCT) results in realistic emergency core cooling system (ECCS) evaluation models. This evaluation provides an estimated effect of fuel pellet TCD and peaking factor burndown on the PCT calculation for the Comanche Peak Unit 2 BE LBLOCA AOR. This change represents a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451 (Reference 2).
Affected Evaluation Model 2004 Westinghouse Realistic Large Break LOCA Evaluation Model Using ASTRUM.
Estimated Effect A quantitative evaluation, as discussed in Reference 3, was performed to assess the PCT effect of fuel pellet TCD and peaking factor bumdown on the Comanche Peak Unit 2 BE LBLOCA analysis and concluded that the estimated PCT impact is 190'F for 10 CFR 50.46 reporting purposes. The peaking factor burndown included in the evaluation is provided in Table I is conservative for the current cycle.
Luminant Power and its vendor, Westinghouse Electric Company LLC, utilize processes which ensure that the LOCA analysis input values conservatively bound the as-operated plant values for those parameters and will be validated as part of the reload design process.
Table 1: Peaking Factors Assumed in the Evaluation of TCD Rod Burnup FdH (1),(2) FQ Transient (1) FQ Steady-State (MWd/MTU) 0 1.600 2.500 2.000 30,000 1.600 2.500 2.000 60,000 1.400 1.875 1.500 62,000 1.400 1.875 1.500 (1) Includes uncertainties.
(2) Hot assembly average power follows the same burndown, since it is a function of FdH.
References
- 1. NRC Information Notice 2011-21, McGinty, T. J., and Dudes, L. A., "Realistic Emergency Core Cooling System Evaluation Model Effects Resulting From Nuclear Fuel Thermal Conductivity Degradation," December 13, 2011. (NRC ADAMS # ML113430785)
- 2. WCAP-13451, "Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting,"
October 1992.
- 3. OG-12-386, "For Information Only - Input Supporting the PWROG LBLOCA Program Regarding Nuclear Fuel Thermal Conductivity Degradation (PA-ASC-1073, Revision 0)
(Proprietary/ Non-Proprietary)," September 18, 2012.
to TXX-12146 Page 2 of 3 Plant Name: Comanche Peak Unit 2 Utility Name: Luminant Revision Date: 9/20/2012 Analysis Information EM: ASTRUM (2004) Analysis Date: 7/27/2007 Limiting Break Size: Guillotine FQ: 2.5 FdH: 1.6 Fuel: OFA SGTP (%): 10 Notes:
Clad Temp (°F) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 1632 PCT ASSESSMENTS (Delta PCT)
A. PRIOR ECCS MODEL ASSESSMENTS
- 1. None 0 B. PLANNED PLANT MODIFICATION EVALUATIONS 0
- 1. None C. 2012 ECCS MODEL ASSESSMENTS 1 . Evaluation of Fuel Pellet Thermal Conductivity 190 2 (a)
Degradation and Peaking Factor Burndown D. OTHER
References:
- 1. WCAP-16763-P, Revision 1, "Best-Estimate Analysis of the Large-Break Loss-of-Coolant Accident for the Comanche Peak Nuclear Power Plant Unit 2 Using the ASTRUM Methodology," March 2009.
- 2. LTR-LIS-12-410, "Comanche Peak Units I and 2, 10 CFR 50.46 Notification and Reporting for Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown," September 20, 2012.
Notes:
(a) This evaluation credits peaking factor burndown, see Reference 2.
toTXX-12146 Page 3 of 3 Plant Name: Comanche Peak Unit 2 Cycle 14 Utility Name: Luminant Revision Date: 9/20/2012 Analysis Information EM: ASTRUM (2004) Analysis Date: 7/27/2007 Limiting Break Size: Guillotine FQ: 2.5 FdH: 1.6 Fuel: OFA SGTP (0): 10 Notes:
Clad Temp (°F) Ref. Notes LICENSING BASIS Analysis-Of-Record PCT 1632 1 PCT ASSESSMENTS (Delta PCT)
A. PRIOR ECCS MODEL ASSESSMENTS
- 1. None 0 B. PLANNED PLANT MODIFICATION EVALUATIONS 0 2 1 . PBOT/PMID Violation C. 2012 ECCS MODEL ASSESSMENTS 1 . Evaluation of Fuel Pellet Thermal Conductivity 190 3 (a)
Degradation and Peaking Factor Burndown D. OTHER
References:
- 1. WCAP-16762-P, Revision 1, "Best-Estimate Analysis of the Large-Break Loss-of-Coolant Accident for the Comanche Peak Nuclear Power Plant Unit 2 Using the ASTRUM Methodology," March 2009.
- 2. LTR-LIS-12-498, "LBLOCA PCT Rackup Sheet Update for the Evaluation of the Comanche Peak Unit 2 Cycle 14 PBOT/PMID Violations," September 2012.
- 3. LTR-LIS-12-410, "Comanche Peak Units 1 and 2, 10 CFR 50.46 Notification and Reporting for Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown," September 20, 2012.
Notes:
(a) This evaluation credits peaking factor burndown, see Reference 3.