NMP1L3374, 10 CFR 50.46 Annual Report

10 CFR 50.46 Annual Report

ML21027A028
Person / Time
Site:	Nine Mile Point
Issue date:	01/27/2021
From:	David Gudger Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NMP1L3374
Download: ML21027A028 (10)

Text

200 Exelon Way Kennett Square, PA 19348 www.exeloncorp.com 10 CFR 50.46 NMP1L3374 January 27, 2021 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Nine Mile Point Nuclear Station, Units 1 and 2 Renewed Facility Operating License Nos. DPR-63 and NPF-69 NRC Docket Nos. 50-220 and 50-410

Subject:

10 CFR 50.46 Annual Report

Reference:

1) Letter from J. Barstow (Exelon Generation Company, LLC) to U.S.

Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated January 27, 2020.

The purpose of this letter is to submit the 10 CFR 50.46 annual reporting information for Nine Mile Point Nuclear Station (NMP). Since the submittal of Reference 1, vendor notification 2020-01 was issued against NMP Unit 1 and Unit 2. Notification 2020-01 identifies errors in the PRIME fuel rod code for Zircaloy irradiation growth after breakaway neutron fluence, incorrect Zircaloy thermal conductivity applied to the Zr barrier for cladding temperature drop and gap conductance during pellet-cladding gap closure. These notifications are included in this report.

Three attachments are included with this letter that provide the current NMP 10 CFR 50.46 status. Attachments 1 and 2 provide the Peak Cladding Temperature and the rack-up sheets for the NMP Unit 1 and NMP Unit 2 LOCA analyses, respectively. Attachment 3, "Assessment Notes," contains a detailed description of each change/error reported.

There are no commitments contained in this letter. If you have any questions, please contact Ron Reynolds at 610-765-5247.

Respectfully, David T. Gudger Senior Manager - Licensing Exelon Generation Company, LLC

10 CFR 50.46 Annual Report Januay 27, 2021 Page 2 Attachments: 1) Peak Cladding Temperature Rack-Up Sheet for NMP Unit 1

2) Peak Cladding Temperature Rack-Up Sheet for NMP Unit 2

3) Assessment Notes, NMP cc: USNRC Administrator, Region I USNRC Senior Project Manager, NMP USNRC Senior Resident Inspector, NMP A. L. Peterson, NYSERDA

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 January 27, 2021 Peak Cladding Temperature Rack-Up Sheet for NMP Unit 1 Nine Mile Point Nuclear Station, Unit 1

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of January 27, 2021 Attachment 1 Peak Cladding Temperature Rack-Up Sheet for NMP Unit 1 Page 1 of 1 PLANT NAME: Nine Mile Point Nuclear Station, Unit 1 ECCS EVALUATION MODEL: TRACG-LOCA REPORT REVISION DATE: 1/27/2021 CURRENT OPERATING CYCLE: 24 ANALYSIS OF RECORD

1. 002N3714, Revision 0, Nine Mile Point Nuclear Station Unit 1 TRACG-LOCA Loss-of-Coolant Accident Analysis for GNF2 Fuel, March 2017 Fuel Analyzed in Calculations and in Operation: GNF2 Limiting Fuel Type: GNF2 Limiting Single Failure: 1 Diesel Generator Limiting Break Size and Location: Recirculation Discharge 200% (7.233 ft2) split break at 100% power and flow Reference Peak Cladding Temperature (PCT): GNF2 = 2105°F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS 10 CFR 50.46 Report dated January 27, 2017 (Note 1) PCT = N/A 10 CFR 50.46 Report dated January 26, 2018 (Note 2) PCT = -8°F 10 CFR 50.46 Report dated January 25, 2019 (Note 3) PCT = 0°F 10 CFR 50.46 Report dated January 27, 2020 (Note 4) PCT = 0°F NET PCT 2097°F B. CURRENT LOCA MODEL ASSESSMENTS Notification 2020-01 (Note 5) PCT = 0°F Total PCT change from current assessments PCT = 0°F Cumulative PCT change from current assessments lPCTl = 0°F NET PCT 2097°F

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 January 27, 2021 Peak Cladding Temperature Rack-Up Sheet for NMP Unit 2 Nine Mile Point Nuclear Station, Unit 2

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of January 27, 2021 Attachment 2 Peak Cladding Temperature Rack-Up Sheet for NMP Unit 2 Page 1 of 1 PLANT NAME: Nine Mile Point Nuclear Station, Unit 2 ECCS EVALUATION MODEL: SAFER/PRIME REPORT REVISION DATE: 1/27/2021 CURRENT OPERATING CYCLE: 18 ANALYSES OF RECORD

1. 002N4205-R0, "Nine Mile Point Unit 2 GNF2 ECCS-LOCA Evaluation," December 2015 Fuel Analyzed in Calculations and in Operation: GNF2 Limiting Fuel Type: GNF2 Limiting Single Failure: High Pressure Core Spray - Diesel Generator Limiting Break Size and Location: 0.07 ft2 Recirculation Suction Line Break Reference Peak Cladding Temperature (PCT): GNF2 = 1690°F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS 10 CFR 50.46 Report dated January 27, 2017 (Note 6) PCT = N/A 10 CFR 50.46 Report dated January 26, 2018 (Note 7) PCT = 0°F 10 CFR 50.46 Report dated January 25, 2019 (Note 8) PCT = N/A 10 CFR 50.46 Report dated January 27, 2020 (Note 9) PCT = 0°F NET PCT 1690°F B. CURRENT LOCA MODEL ASSESSMENTS Notification 2020-01 (Note 10) PCT = 0°F Total PCT change from current assessments PCT = 0°F Cumulative PCT change from current assessments lPCTl = 0°F NET PCT 1690°F

ATTACHMENT 3 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 January 27, 2021 Assessment Notes, NMP Nine Mile Point Nuclear Station

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of January 27, 2021 Attachment 3 Assessment Notes, NMP Page 1 of 3

1) Prior LOCA Assessments (Unit 1)

Subsequent to the Reference 1 10 CFR 50.46 annual report, NMP Unit 1 replaced its existing SAFER/CORECOOL/PRIME analysis with a new TRACG-LOCA analysis

[Reference 2]. The TRACG-LOCA analysis was implemented concurrent with the start of fuel Cycle 23. Because all GE11 fuel was discharged prior to Cycle 23, Cycle 23 contains a full core of GNF2 fuel, and the TRACG-LOCA analysis is applicable to GNF2 fuel only. No SAFER/CORECOOL/PRIME notifications were received between the last 10 CFR 50.46 annual report and the start of Cycle 23.

[Reference 1: Letter from J. Barstow (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated January 27, 2017]

[Reference 2: 002N3714, Revision 0, Nine Mile Point Nuclear Station Unit 1 TRACG-LOCA Loss-of-Coolant Accident Analysis for GNF2 Fuel, March 2017]

2) Prior LOCA Model Assessments (Unit 1)

Subsequent to TRACG-LOCA implementation (Note 1), one notification was received.

Notification 2017-03 describes a counter-current flow limitation coefficient that was incorrectly applied within the bypass region. The PCT impact was estimated to be -8°F.

[

Reference:

Letter from J. Barstow (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated January 26, 2018]

3) Prior LOCA Model Assessments (Unit 1)

Subsequent to the previous 10 CFR 50.46 report (Note 2), one notification was received.

Notification 2018-01 describes that, for some uncertainties, standard deviation were used that are inconsistent with the values approved by TRACG-LOCA Licensing Topical Report.

An analysis was performed using the approved standard deviations, and the results showed that the effect was not statistically significant.. The PCT impact was estimated to be 0°F.

[

Reference:

Letter from J. Barstow (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated January 25, 2019]

4) Prior LOCA Model Assessment (Unit 1)

Subsequent to the previous 10 CFR 50.46 report (Note 3), two notifications were received.

Notification 2019-01 describes that channel inlet subcooling was found to be incorrect in TRACG when multiple unheated nodes were modeled. Notification 2019-02 describes that the radiation heat transfer was found to be incorrect in TRACG due to a memory overwrite in the computer software. For each error, the PCT impact was estimated to be 0°F.

5) Current LOCA Model Assessments (Unit 1)

Subsequent to the previous 10 CFR 50.46 report (Note 4), one notification was received.

Notification 2020-01 identifies errors in the PRIME fuel rod code for Zircaloy irradiation growth after breakaway neutron fluence, incorrect Zircaloy thermal conductivity applied to

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of January 27, 2021 Attachment 3 Assessment Notes, NMP Page 2 of 3 the Zr barrier for cladding temperature drop and gap conductance during pellet-cladding gap closure. The notification shows 0 °F PCT impact.

6) Prior LOCA Model Assessments (Unit 2)

GNF2 fuel was inserted into the Unit 2 reactor core [Reference 1]. The GNF2 ECCS-LOCA analysis of record is shown as Reference 2. There are no evaluation model changes or errors reported against the GNF2 analysis since its introduction into Unit 2.

[Reference 1: Letter from James Barstow (Exelon Generation Company, LLC) to U.S.

Nuclear Regulatory Commission, 10 CFR 50.46 Annual Report, dated January 27, 2017 (NMP1L3126)]

[Reference 2: 002N4205-R0, "Nine Mile Point Unit 2 GNF2 ECCS-LOCA Evaluation,"

December 2015]

7) Prior LOCA Model Assessments (Unit 2)

Subsequent to the previous 10 CFR 50.46 report (Note 6), two notifications were received from the vendor. Notification 2017-01 describes an incorrect assumption of lower tie plate leakage with an estimated PCT impact of 0 °F for GNF2 fuel. Notification 2017-02 describes a change in the fuel rod upper plenum modeling with an estimated PCT impact of 0 °F for GNF2 fuel.

[

Reference:

Letter from J. Barstow (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated January 26, 2018]

8) Prior LOCA Model Assessments (Unit 2)

Subsequent to the previous 10 CFR 50.46 report (Note 7), no notifications were received.

[

Reference:

Letter from J. Barstow (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated January 25, 2019]

9) Prior LOCA Model Assessments (Unit 2)

Subsequent to the previous 10 CFR 50.46 report (Note 8), one notification was received from the vendor. 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 for GNF2 fuel.

[

Reference:

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

Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated January 27, 2020 (NMP1L3325)]

10) Current LOCA Model Assessments (Unit 2)

Subsequent to the previous 10 CFR 50.46 report (Note 9), all GE14 fuel was discharged from the core, and the NMP2 core is fully loaded with the GNF2 fuel type.

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of January 27, 2021 Attachment 3 Assessment Notes, NMP Page 3 of 3 Subsequent to the previous 10 CFR 50.46 report (Note 9), one notification was received.

Notification 2020-01 identifies errors in the PRIME fuel rod code for Zircaloy irradiation growth after breakaway neutron fluence, incorrect Zircaloy thermal conductivity applied to the Zr barrier for cladding temperature drop and gap conductance during pellet-cladding gap closure. The notification shows 0 °F PCT impact.