ML24078A115
ML24078A115 | |
Person / Time | |
---|---|
Site: | Calvert Cliffs ![]() |
Issue date: | 03/18/2024 |
From: | David Helker Constellation Energy Generation |
To: | Office of Nuclear Reactor Regulation, Document Control Desk |
References | |
Download: ML24078A115 (1) | |
Text
200 Exelon Way Kennett Square, PA 19348 www.Constellation.com 10 CFR 50.46 March 18, 2024 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 Docket Nos. 50-317 and 50-318
Subject:
10 CFR 50.46 Annual Report
Reference:
Letter from David P. Helker (Constellation Energy Generation, LLC) to U.S.
NRC, "10 CFR 50.46 Annual Report," dated March 20, 2023.
The purpose of this letter is to submit the 10 CFR 50.46 annual reporting information for Calvert Cliffs Nuclear Power Plant (CCNPP) Units 1 and 2. The referenced document is the most recent annual 10 CFR 50.46 Annual Report submitted to the U.S. NRC.
There were no changes or errors reported against the CCNPP Unit 1 and Unit 2 Small Break Loss-of-Coolant Accident Evaluation Model or Realistic Large Break Loss-of-Coolant Accident Evaluation Model during the previous annual reporting period.
Two attachments are included with this letter that provide the current CCNPP 10 CFR 50.46 status. Attachment 1 provides the Peak Cladding Temperature rack-up sheets for the annual report for CCNPP Units 1 and 2. Attachment 2, Assessment Notes, contains a detailed description of each model assessment and error reported.
There are no regulatory commitments contained in this letter.
Should you have any questions concerning this submittal, please contact Wendi Para at (267) 533-5208.
Respectfully, David P. Helker Sr. Manager - Licensing Constellation Energy Generation, LLC Attachments: 1. Peak Cladding Temperature Rack-Up Sheet for CCNPP, Units 1 and 2
- 2. Assessment Notes for CCNPP, Units 1 and 2 cc:
USNRC Administrator, Region I USNRC Project Manager, CCNPP USNRC Senior Resident Inspector, CCNPP S. Seaman, State of Maryland
ATTACHMENT 1 10 CFR 50.46 "Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors" Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2024 Peak Cladding Temperature Rack-Up Sheets for CCNPP, Units 1 and 2
- Peak Cladding Temperature Rack-up Sheet (Annual)
PLANT NAME:
Calvert Cliffs Unit 1 ECCS EVALUATION MODEL:
Small Break Loss of Coolant Accident (SBLOCA)
REPORT REVISION DATE:
03/18/2024 CURRENT OPERATING CYCLE:
27 ANALYSIS OF RECORD (AOR)
Evaluation Model: EMF-2328(P)(A), Revision 0, Supplement 1(P)(A), Revision 0 Calculation: ANP-3641, March 2018 Fuel: HTP 14 x 14 M5 Limiting EM Fuel Type: HTP 14 x 14 M5 Limiting Single Failure: Loss of one emergency diesel generator Limiting Break Size and Location: 0.34 ft2 Break in the Cold Leg Pump Discharge Reference Peak Cladding Temperature (PCT)
PCT = 1648°F MARGIN ALLOCATION A. PRIOR LOSS OF COOLANT ACCIDENT (LOCA) MODEL ASSESSMENTS 10 CFR 50.46 report dated March 18, 2019 (Note 7)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2020 (Note 8)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2021 (Note 9)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2022 (Note 10)
PCT = 0°F 10 CFR 50.46 report dated March 20, 2023 (Note 11)
PCT = 0°F NET PCT PCT = 1648°F B. CURRENT LOCA MODEL ASSESSMENTS (Note 12)
None PCT = 0°F Total PCT change from current assessments PCT = 0°F Cumulative PCT change from current assessments PCT = 0°F NET PCT PCT = 1648°F Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2024 Peak Cladding Temperature Rack-Up Sheet for CCNPP Units 1 and 2 Page 1 of 4
PLANT NAME:
Calvert Cliffs Unit 1 ECCS EVALUATION MODEL:
Realistic Large Break Loss of Coolant Accident (RLBLOCA)
REPORT REVISION DATE:
03/18/2024 CURRENT OPERATING CYCLE:
27 AOR Evaluation Model: EMF-2103(P)(A)
Calculation: ANP-3043(P), December 2011 Fuel: HTP 14 x 14 M5 Limiting EM Fuel Type: HTP 14 x 14 M5 Limiting Single Failure: Loss of one emergency diesel generator Limiting Break Size and Location: Guillotine break (4.5832 ft2/side) in the Cold Leg Pump Discharge Reference PCT PCT = 1620°F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS 10 CFR 50.46 report dated March 20, 2014 (Note 2)
PCT = 14°F 10 CFR 50.46 report dated July 14, 2015 (Note 3)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2016 (Note 4)
PCT = 0°F 10 CFR 50.46 report dated March 17, 2017 (Note 5)
PCT = 0°F 10 CFR 50.46 report dated March 16, 2018 (Note 6)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2019 (Note 7)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2020 (Note 8)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2021 (Note 9)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2022 (Note 10)
PCT = 0°F 10 CFR 50.46 report dated March 20, 2023 (Note 11)
PCT = 0°F NET PCT PCT = 1634°F B. CURRENT LOCA MODEL ASSESSMENTS (Note 12)
None PCT = 0°F Total PCT change from current assessments PCT = 0°F Cumulative PCT change from current assessments PCT = 0°F NET PCT PCT = 1634°F Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2024 Peak Cladding Temperature Rack-Up Sheet for CCNPP Units 1 and 2 Page 2 of 4
PLANT NAME:
Calvert Cliffs Unit 2 ECCS EVALUATION MODEL:
Small Break Loss of Coolant Accident (SBLOCA)
REPORT REVISION DATE:
03/18/2024 CURRENT OPERATING CYCLE:
25 AOR Evaluation Model: EMF-2328(P)(A), Revision 0, Supplement 1(P)(A), Revision 0 Calculation: ANP-3641, March 2018 Fuel: HTP 14 x 14 M5 Limiting EM Fuel Type: HTP 14 x 14 M5 Limiting Single Failure: Loss of one emergency diesel generator Limiting Break Size and Location: 0.34 ft2 break in the Cold Leg Pump Discharge Reference PCT PCT = 1648°F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS 10 CFR 50.46 report dated March 18, 2019 (Note 7)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2020 (Note 8)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2021 (Note 9)
PCT = 20°F 10 CFR 50.46 report dated March 18, 2022 (Note 10)
PCT = 0°F 10 CFR 50.46 report dated March 20, 2023 (Note 11)
PCT = 0°F NET PCT PCT = 1668°F B. CURRENT LOCA MODEL ASSESSMENTS (Note 12)
None PCT = 0°F Total PCT change from current assessments PCT = 0°F Cumulative PCT change from current assessments PCT = 0°F NET PCT PCT = 1668°F Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2024 Peak Cladding Temperature Rack-Up Sheet for CCNPP Units 1 and 2 Page 3 of 4
PLANT NAME:
Calvert Cliffs Unit 2 ECCS EVALUATION MODEL:
Realistic Large Break Loss of Coolant Accident (RLBLOCA)
REPORT REVISION DATE:
03/18/2024 CURRENT OPERATING CYCLE:
25 AOR Evaluation Model: EMF-2103(P)(A)
Calculation: ANP-3043(P), December 2011 Fuel: HTP 14 x 14 M5 Limiting EM Fuel Type: HTP 14 x 14 M5 Limiting Single Failure: Loss of one emergency diesel generator Limiting Break Size and Location: Guillotine break (4.5832 ft2/side) in the Cold Leg Pump Discharge Reference PCT PCT = 1620°F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS 10 CFR 50.46 report dated April 22, 2013 (Note 1)
PCT = 8°F 10 CFR 50.46 report dated March 20, 2014 (Note 2)
PCT = 6°F 10 CFR 50.46 report dated July 14, 2015 (Note 3)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2016 (Note 4)
PCT = 0°F 10 CFR 50.46 report dated March 17, 2017 (Note 5)
PCT = 0°F 10 CFR 50.46 report dated March 16, 2018 (Note 6)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2019 (Note 7)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2020 (Note 8)
PCT = 0°F 10 CFR 50.46 report dated March 18, 2021 (Note 9)
PCT = 75°F 10 CFR 50.46 report dated March 18, 2022 (Note 10)
PCT = 0°F 10 CFR 50.46 report dated March 20, 2023 (Note 11)
PCT = 0°F NET PCT PCT = 1709°F B. CURRENT LOCA MODEL ASSESSMENTS (Note 12)
None PCT = 0°F Total PCT change from current assessments PCT = 0°F Cumulative PCT change from current assessments PCT = 0°F NET PCT PCT =1709°F Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2024 Peak Cladding Temperature Rack-Up Sheet for CCNPP Units 1 and 2 Page 4 of 4
ATTACHMENT 2 10 CFR 50.46 "Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors" Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2024 Assessment Notes for CCNPP, Units 1 and 2
- Assessment Notes
- 1. Prior LOCA Model Assessment The 10 CFR 50.46 combined 30-day and annual report dated April 22, 2013 (NRC ADAMS Accession Number ML13115A279) reported a new licensing basis PCT for Calvert Cliffs Unit 2 (ANP-3043) RLBLOCA applicable to once-and twice-burned fuel and two errors, respectively. While the ANP-3043 calculation was completed in December 2011, page 2 of the report states that this became the new analysis licensing basis for Unit 2 as of March 22, 2013. The report changed the licensing basis Calvert Cliffs Unit 2 RLBLOCA applicable to AREVA fuel to 1620°F PCT. The previous RLBLOCA analysis (ANP-2834) assumed fresh fuel was limiting and applied a statistical treatment to the multiplier on decay heat. The inclusion of the burnup dependent RLBLOCA report satisfies the Technical Specification Appendix C license condition and allows for a full core of AREVA fuel in Calvert Cliffs Unit 2.
The 10 CFR 50.46 report reported two errors. One error was due to Cathcart-Pawel uncertainty implementation in RLBLOCA application resulting in a 0°F PCT impact. A second error was in the S-RELAP5 Sleicher-Rouse correlation used for predicting the heat transfer to single-phase vapor resulting in an 8°F PCT to Calvert Cliffs Unit 2 RLBLOCA.
- 2. Prior LOCA Model Assessment The 10 CFR 50.46 combined 30-day and annual report dated March 20, 2014 (NRC ADAMS Accession Number ML14080A307) reported a new licensing basis PCT for Calvert Cliffs Unit 1 (ANP-3043) RLBLOCA applicable to once-and twice-burned fuel and a new error, respectively. While the ANP-3043 calculation was completed in December 2011, page 2 of the report states that this became the new analysis licensing basis for Unit 1 as of March 12, 2014. The report changed the licensing basis to Calvert Cliffs Unit 1 RLBLOCA applicable to AREVA fuel to 1620°F PCT. The previous RLBLOCA analysis (ANP-2834) assumed fresh fuel was limiting and applied a statistical treatment to the multiplier on decay heat. The inclusion of the burnup dependent RLBLOCA report satisfies the Technical Specification Appendix C license condition and allows for a full core of AREVA fuel in Calvert Cliffs Unit 1. to this report contains the Unit 1 and Unit 2 10 CFR 50.46 annual report information, which reported a new error due to an issue with the S-RELAP5 routine associated with the RODEX3a fuel rod model resulting in a 6°F PCT impact to Unit 1 and Unit 2 RLBLOCA. This error is in addition to the Sleicher-Rouse correlation error used for predicting the heat transfer to single-phase vapor, which is identified by the 30-day report in of this report for Unit 1. Consistent with the previous annual report identification of the Sleicher-Rouse correlation error for Unit 2 (discussed in Note 1), the Sleicher-Rouse correlation error PCT impact is 8°F for both units. This results in a total 14°F PCT impact when combined with the RODEX3a fuel rod model error.
Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2024 Assessment Notes for CCNPP Units 1 and 2 Page 1 of 4
- 3. Prior LOCA Model Assessment The revised 10 CFR 50.46 annual report for Unit 1 and Unit 2 dated July 14, 2015 (NRC ADAMS Accession Number ML15196A039) reported two new errors applicable to the Unit 1 and Unit 2 RLBLOCA. There was a discovered error in the correlation for vapor absorptivity use in S-RELAP5, applied outside of its intended range of applicability (no limit was imposed on the pressure at which the correlation was applied). The equation used for the absorption coefficient of vapor contains the term of the pressure which needs to be truncated in order to obtain the correct emissivity values for an optically thick steam. The estimated impact of this change on the Unit 1 and Unit 2 RLBLOCA analysis calculated PCT is 0°F. There was another discovered error in the modal decomposition method which led to a detailed examination of the actual axial shapes that were produced by the modal decomposition procedure and it was observed that some of these resulting shapes were significantly different from the 24-node shape that was generated by PWR Core Engineering. These shapes exhibit a super-imposed oscillation created by the modal decomposition that leads to non-physical artificial local peaks and valleys in the shape. When such shapes are generated and used in the LOCA analyses they tend to shift the PCT both in the positive and negative direction depending on application. This led to the conclusion that in future application, the modal decomposition method will not be used and a linear interpolation will be used for the mapping. The linear interpolation provides a significantly better fit for the axial shapes. This evaluation led to a 0°F PCT impact to Calvert Cliffs Unit 1 and 2 RLBLOCA analysis.
- 4. Prior LOCA Model Assessment The 10 CFR 50.46 annual report for Unit 1 and Unit 2 dated March 18, 2016 (NRC ADAMS Accession Number ML16078A067) identified once-burned fuel, UO2 and Gadolinia-bearing (GAD) rods, are generally modeled at a reduced peaking in comparison with the hot fresh UO2 rod. The reduction is achieved by imposing a burnup-dependent multiplier, or cutback factor, specifying the radial peaking as a fraction of the hot rod radial peaking. A review indicated that cutback factors for once-burned GAD rods were instead applied as a fraction of the once-burned UO2 rod resulting in the inadvertent once-burned GAD rods being modeled at a reduced power. This evaluation led to a 0°F PCT impact to Calvert Cliffs Unit 1 and 2 RLBLOCA analysis.
- 5. Prior LOCA Model Assessment The 10 CFR 50.46 annual report for Unit 1 and Unit 2 dated March 17, 2017 (NRC ADAMS Accession Number ML17076A001) reported that there were no errors or changes reported against RLBLOCA during this reporting period.
- 6. Prior LOCA Model Assessment The 10 CFR 50.46 annual report for Unit 1 and Unit 2 dated March 16, 2018 (NRC ADAMS Accession Number ML18075A007) reported that there were no errors or changes reported against RLBLOCA during this reporting period.
Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2024 Assessment Notes for CCNPP Units 1 and 2 Page 2 of 4
- 7. Prior LOCA Model Assessment The 10 CFR 50.46 annual report for Unit 1 and Unit 2 dated March 18, 2019 (NRC ADAMS Accession Number ML19077A129) reported that Calvert Cliffs Units 1 and 2 SBLOCA was re-analyzed using Evaluation Model EMF-2328(P)(A), Revision 0, Supplement 1(P)(A),
Revision 0. The local oxidation and whole core hydrogen remain well within the 10 CFR 50.46 acceptance criteria. The analysis establishes an AOR PCT of 1648°F. No errors in or changes to the EMF-2328(P)(A), Revision 0, Supplement 1(P)(A), Revision 0 analysis were reported.
There were no errors or changes reported against RLBLOCA during this reporting period.
- 8. Prior LOCA Model Assessment The 10 CFR 50.46 annual report for Unit 1 and Unit 2 dated March 18, 2020 (NRC ADAMS Accession Number ML20078F423) reported that there were no errors or changes reported against Calvert Cliffs Units 1 and 2 SBLOCA during this reporting period.
An error in the implementation of the Cathcart-Pawel correlation was discovered. The correlation is used for the calculation of metal-water reaction in the Framatome EMF-2103(P)(A) RLBLOCA methodologies. The correlation for the rate of oxide thickness was used instead of the correlation for the rate of total oxygen consumed. The correlation for the rate of total oxygen consumed is what is expected to be used for the 10 CFR 50.46 (b)(2) criterion. As compared to a total oxygen-based implementation, the use of the oxide-based implementation led to a more conservative prediction of the transient oxidation and heat released during the reaction. The additional heat from the reaction could have resulted in higher calculated values of the analysis PCT. For RLBLOCA though, the difference in results between the two correlation implementations has a negligible impact on PCT. The PCT impact for the Calvert Cliffs Units 1 and 2 RLBLOCA analysis is 0°F.
- 9. Prior LOCA Model Assessment The 10 CFR 50.46 annual report for Unit 1 and Unit 2 dated March 18, 2021 (NRC ADAMS Accession Number ML21077A180) reported that there were no errors or changes reported against Calvert Cliffs Units 1 and 2 SBLOCA or RLBLOCA during the annual reporting period.
A Lead Test Assembly (LTA) with Framatomes PROtect Enhanced Accident Tolerant Fuel (EATF) was first operated in the Calvert Cliffs Unit 2 Cycle 24 core with a startup in March 2021. An EATF LTA is also operating in the Calvert Cliffs Unit 2 Cycle 25 core. The Framatome PROtect product consists of EATF with Chromia doped UO2 pellets and Chromium coated cladding fuel rods.
To cover the PROtect LTA throughout its operating cycles a technical evaluation to assess the potential impacts of the EATF LTA design on the Calvert Cliffs RLBLOCA and SBLOCA licensing bases was performed. The presence of the LTA will not impact the system response characteristics during a LOCA but can impact the fuel performance under those conditions. Since the EATF product testing is ongoing, there is not a sufficient quantity of data to fully support development of new analytical models or material property definition.
Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2024 Assessment Notes for CCNPP Units 1 and 2 Page 3 of 4
Therefore, the evaluations were performed from first principles, conservative assumptions and supporting calculations. The potential LOCA performance impacts were evaluated individually. A bounding PCT penalty for the potential impacts of the EATF was then determined. The process described for developing penalty factors associated with the LTA was approved in ML20363A242.
The evaluation resulted in a PCT penalty of +75°F for RLBLOCA and +20°F for SBLOCA.
The penalty for SBLOCA is being provided for completeness. These penalties apply during operation with the EATF LTA. Calvert Cliffs Unit 2 remains within the acceptance criteria set forth in 10 CFR 50.46. Based on the small number of LTAs (1 for Calvert Cliffs Unit 2),
minimal changes to co-resident fuel, and large margin to regulatory acceptance criteria for PCT, use of the bounding PCT penalty as approved in ML20363A242 is acceptable and no re-analysis is required.
- 10. Prior LOCA Model Assessment The 10 CFR 50.46 annual report for Unit 1 and Unit 2 dated March 18, 2022 (NRC ADAMS Accession Number ML22077A003) reported that there were no errors or changes reported against SBLOCA or RLBLOCA during this reporting period.
- 11. Current LOCA Model Assessment The 10 CFR 50.46 annual report for Unit 1 and Unit 2 dated March 20, 2023 (NRC ADAMS Accession Number ML23079A036) reported that there were no errors or changes reported against SBLOCA or RLBLOCA during this reporting period.
- 12. Current LOCA Model Assessment There were no changes or errors reported against the Calvert Cliffs Unit 1 and Unit 2 SBLOCA evaluation model or RLBLOCA evaluation model during this annual reporting period.
Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2024 Assessment Notes for CCNPP Units 1 and 2 Page 4 of 4