ML20225A160

Transmittal of 10 CFR 50.46 Annual Report

ML20225A160
Person / Time
Site:	Peach Bottom
Issue date:	08/12/2020
From:	David Helker Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML20225A160 (10)

Text

200 Exelon Way Kennett Square, PA 19348 www.exeloncorp.com 10 CFR 50.46 August 12, 2020 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 NRC Docket Nos. 50-277 and 50-278

Subject:

10 CFR 50.46 Annual Report

Reference:

Letter from David T. Gudger (Exelon Generation Company, LLC) to the U.S.

Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated August 12, 2019 The purpose of this letter is to transmit the 10 CFR 50.46 reporting information for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3. The previous 50.46 report for PBAPS, Units 2 and 3, (Reference) provided the cumulative Peak Cladding Temperature (PCT) errors for the most recent fuel designs through August 12, 2019.

Two new 10 CFR 50.46 notifications were received from the fuel vendor since the last 2019 annual report (Reference) submitted to NRC. However, the total PCT value of 1925oF reported in the last annual report (Reference) is unchanged for this report.

There are no regulatory commitments in this letter.

If you have any questions concerning this letter, please contact Richard Gropp at 610-765-5557.

Respectfully, David P. Helker Sr. Manager, Licensing and Regulatory Affairs Exelon Generation Company, LLC Attachments: 1. Peach Bottom Unit 2 l SAFER/PRIME l GNF2 Fuel 10 CFR 50.46 Report

2. Peach Bottom Unit 3 l SAFER/PRIME l GNF2 Fuel 10 CFR 50.46 Report

3. Assessment Notes

U.S. Nuclear Regulatory Commission Peach Bottom Atomic Power Station, Units 2 and 3 10 CFR 50.46 Report August 12, 2020 Page 2 cc: w/Attachments USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, PBAPS USNRC Project Manager, PBAPS W. DeHaas, Pennsylvania Bureau of Radiation Protection S. Seaman, State of Maryland

ATTACHMENT 1 Peach Bottom Unit 2 l SAFER/PRIME l GNF2 Fuel 10 CFR 50.46 Report

Peach Bottom Unit 2 l SAFER/PRIME l GNF2 Fuel Attachment 1 10 CFR 50.46 Report Page 1 of 1 PLANT NAME: Peach Bottom Unit 2 ECCS EVALUATION MODEL: SAFER/PRIME EVALUATION MODEL VENDOR: GNF/GEH REPORT REVISION DATE: August 12, 2020 CURRENT OPERATING CYCLE: 23 ANALYSIS OF RECORD CALCULATIONS

1. Project Task Report, Exelon Generation Company LLC, Peach Bottom Atomic Power Station, Units 2 & 3 MELLLA+ Task T0407: ECCS-LOCA Performance, 0000-0162-2354-R0, Revision 0, (PLM 000N0296 Revision 0), December 2013.

Fuels Analyzed in Calculations and in Operation: GNF2 Limiting Fuel Type: GNF2 Limiting Single Failure: Battery Failure Limiting Break Location: Recirculation Discharge Line Limiting Break Size: 0.05 ft² (Small Break)

Reference Peak Cladding Temperature (PCT) for GNF2 Fuel: 1920°F MARGIN ALLOCATION A. PRIOR LOCA ASSESSMENTS (Note 1):

10 CFR 50.46 Report dated August 15, 2014 (Note 1.1) GNF2: PCT = +5°F 10 CFR 50.46 Report dated August 10, 2016 (Note 1.2) GNF2: PCT = 0°F 10 CFR 50.46 Report dated August 10, 2017 (Note 1.3) GNF2: PCT = 0°F 10 CFR 50.46 Report dated August 10, 2018 (Note 1.4) GNF2: PCT = 0°F 10 CFR 50.46 Report dated August 12, 2019 (Note 1.5) GNF2: PCT = 0°F Net PCT GNF2: 1925°F B. CURRENT LOCA ASSESSMENTS (Note 2):

Total PCT Change from Current Assessments (Note 2) GNF2: PCT = 0°F Cumulative PCT Change from Current Assessments GNF2: lPCTl = 0°F Net PCT GNF2: 1925°F

ATTACHMENT 2 Peach Bottom Unit 3 l SAFER/PRIME l GNF2 Fuel 10 CFR 50.46 Report

Peach Bottom Unit 3 l SAFER/PRIME l GNF2 Fuel Attachment 2 10 CFR 50.46 Report Page 1 of 1 PLANT NAME: Peach Bottom Unit 3 ECCS EVALUATION MODEL: SAFER/PRIME EVALUATION MODEL VENDOR: GNF/GEH REPORT REVISION DATE: August 12, 2020 CURRENT OPERATING CYCLE: 23 ANALYSIS OF RECORD CALCULATIONS

1. Project Task Report, Exelon Generation Company LLC, Peach Bottom Atomic Power Station, Units 2 & 3 MELLLA+ Task T0407: ECCS-LOCA Performance, 0000-0162-2354-R0, Revision 0, (PLM 000N0296 Revision 0), December 2013.

Fuels Analyzed in Calculations and in Operation: GNF2 Limiting Fuel Type: GNF2 Limiting Single Failure: Battery Failure Limiting Break Location: Recirculation Discharge Line Limiting Break Size: 0.05 ft² (Small Break)

Reference Peak Cladding Temperature (PCT) for GNF2 Fuel: 1920°F MARGIN ALLOCATION A. PRIOR LOCA ASSESSMENTS (Note 1):

10 CFR 50.46 Report dated August 15, 2014 (Note 1.1) GNF2: PCT = +5°F 10 CFR 50.46 Report dated August 10, 2016 (Note 1.2) GNF2: PCT = 0°F 10 CFR 50.46 Report dated August 10, 2017 (Note 1.3) GNF2: PCT = 0°F 10 CFR 50.46 Report dated August 10, 2018 (Note 1.4) GNF2: PCT = 0°F 10 CFR 50.46 Report dated August 12, 2019 (Note 1.5) GNF2: PCT = 0°F Net PCT GNF2: 1925°F B. CURRENT LOCA ASSESSMENTS (Note 2):

Total PCT Change from Current Assessments (Note 2) GNF2: PCT = 0°F Cumulative PCT Change from Current Assessments GNF2: lPCTl = 0°F Net PCT GNF2: 1925°F

ATTACHMENT 3 Assessment Notes 10 CFR 50.46 Report

Assessment Notes Attachment 3 10 CFR 50.46 Report Page 1 of 3 Assessment Notes

1. Prior LOCA Assessment The last 10 CFR 50.46 annual report submitted to the NRC was on August 12, 2019 (Reference 1). This report documents a Net PCT of 1925oF; a licensing basis PCT of 1920o F from the analysis of record report, and a total PCT adder of +5oF for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

[Reference 1: Letter from David T. Gudger (Exelon Generation Company, LLC) to U.S.

Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated August 12, 2019.]

1.1. Prior LOCA Assessment - 2014 The referenced letter reported four vendor notifications that were received.

1. The first notification addressed several accumulated updates to the SAFER04A model. The code maintenance changes had an individually and collectively insignificant effect on calculated peak cladding temperature.

2. The second notification was for a correction to a logic error that was isolated, occurring with an indication that the expected systems mass diverged from the calculated actual system mass. This error affected the Emergency Core Cooling System (ECCS) flow credited as reaching the core. Correction of this error resulted in a +10°F Peak Cladding Temperature (PCT) change for GNF2 fuel.

3. The third notification addressed an error with the imposed minimum Pressure Differential (p) for droplet flow above a two-phase level in the core. This error could have offered an inappropriate steam cooling benefit above the core two phase level. To correct this error an explicit core pressure drop calculation was applied without regard to droplet condition resulting in a PCT of -10°F for GNF2 fuel.

4. The forth notification addressed an incorrect pressure head representation when defining the Counter Current Flow Limitation (CCFL). Correction of this error resulted in a +5°F PCT change for GNF2 fuel.

Note that the 10 CFR 50.46 notifications discussed in the referenced report are applicable to the Unit 2 and Unit 3 MELLLA+ LOCA analysis and the net effect of these notifications is +5°F

[

Reference:

Letter from James Barstow (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated August 15, 2014.]

Assessment Notes Attachment 3 10 CFR 50.46 Report Page 2 of 3 1.2. Prior LOCA Assessment - 2016 The referenced letter reported that PBAPS, Units 2 and 3, implemented Maximum Extended Load Line Limit Analysis Plus (MELLLA+) for which a new LOCA analysis was performed. PBAPS, Units 2 and 3, transitioned to MELLLA+

operation mid-cycle in April 2016 and May 2016, respectively. The error notifications reported in Assessment Note 1.1 are applicable to the PBAPS, Units 2 and 3, MELLLA+ LOCA analysis. The notifications were issued subsequent to the performance of the MELLLA+ LOCA analysis, but prior to its implementation.

[

Reference:

Letter from James Barstow (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated August 10, 2016.]

1.3. Prior LOCA Assessment - 2017 The referenced letter reported two (2) vendor notifications regarding Emergency Core Cooling System (ECCS) modeling changes/errors applicable to PBAPS (Notifications 2017-01 and 2017-02). These notifications described issues related to the improper modelling of lower tie plate leakage for the GNF2 fuel design and changes to modeling of the fuel rod plenum for 10x10 fuel.

Correction of these errors each resulted in a 0°F PCT change for GNF2 fuel.

The referenced letter reported a change in the Level 3 setpoint. The impact of this change on the Loss of Coolant Accident (LOCA) analysis was assessed in GNF Report 003N4534-R0, "Peach Bottom Level 3 Analytical Limit Reduction,"

dated May 25, 2016, which concluded that there is no impact on the licensing basis PCT for PBAPS.

[

Reference:

Letter from David T. Gudger (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated August 10, 2017.]

1.4. Prior LOCA Assessment - 2018 The referenced letter reported no changes/errors against the PBAPS LOCA Analysis of Record during this reporting period.

[

Reference:

Letter from David T. Gudger (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, 10 CFR 50.46 Annual Report, dated August 10, 2018.]

Assessment Notes Attachment 3 10 CFR 50.46 Report Page 3 of 3 1.5. Prior LOCA Assessment - 2019 The referenced letter reported no changes/errors against the PBAPS LOCA Analysis of Record during this reporting period.

[

Reference:

Letter from David T. Gudger (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, 10 CFR 50.46 Annual Report, dated August 12, 2019.]

2. Current LOCA Assessment Subsequent to the previous 10 CFR 50.46 report (Reference 1 in Note 1), two new notifications were received from the vendor; 2019-05 and 2020-01:

- Notification 2019-05 describes that the driving differential pressure for forward and backward bypass leakage is limited with an upper and lower limit in SAFER, and that all the limits were implemented correctly on all nine leakage paths except for one, the lower limit for the control rod guide tube to control rod drive housing interface backward leakage path. The estimated PCT impact of 0 °F was reported for the GNF2 fuel.

- Notification 2020-01 describes errors in the Zircaloy irradiation growth model, Zircaloy thermal conductivity for the Zr barrier, and gap conductance models in the PRIME code. The PRIME code calculates fuel rod conditions as input to the ECCS LOCA evaluation model. The estimated PCT impact of 0 °F was reported for the GNF2 fuel.

Therefore, the total PCT value of 1925oF reported in the last annual report is unchanged for this report.