ML25342A113
| ML25342A113 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 12/15/2025 |
| From: | Scott Wall Plant Licensing Branch III |
| To: | Mudrick C Constellation Energy Generation, Constellation Nuclear |
| Wall, S | |
| Shared Package | |
| ML25342A117 | List: |
| References | |
| EPID L-2025-LLA-0172 | |
| Download: ML25342A113 (0) | |
Text
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION December 15, 2025 Mr. Christopher Mudrick Senior Vice President Constellation Energy Generation, LLC President and Chief Nuclear Officer Constellation Nuclear 200 Exelon Way Kennett Square, PA 19348
SUBJECT:
BRAIDWOOD STATION, UNITS 1 AND 2, AND BYRON STATION, UNIT NOS. 1 AND 2 - AUDIT PLAN IN SUPPORT OF REVIEW OF LICENSE AMENDMENT REQUEST TO MODIFY METHODOLOGY SUPPORTING UTILIZING FRAMATOME GAIA FUEL (EPID L-2025-LLA-0172)
Dear Mr. Mudrick:
By letter dated November 12, 2025 (Agencywide Documents Access and Management System (ADAMS) Package Accession No. ML25318B206), Constellation Energy Generation, LLC (Constellation, the licensee), submitted a license amendment request (LAR) for Braidwood Station, Units 1 and 2, and Byron Station, Unit Nos. 1 and 2. Specifically, the proposed LAR would modify the methodology previously approved for Braidwood and Byron to transition to Framatome GAIA fuel.
The U.S. Nuclear Regulatory Commission (NRC) staff has found the need for a regulatory audit to examine the licensees non-docketed information with the intent to gain understanding, to verify information, or to identify information that requires docketing to support the basis of the licensing or regulatory decision.
The NRC staff will conduct the audit virtually via Teams using a licensee-established electronic portal available to NRC staff. To support an accelerated review schedule, on December 4, 2025, representatives from Constellation agreed to immediately begin the audit. As such, the desktop audit started on December 4, 2025, and will continue through February 28, 2026, with formal audit meetings to be scheduled during this period as needed. The detailed audit plan is enclosed with this letter.
to this letter contains proprietary information. When separated from, this document is DECONTROLLED.
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION If you have any questions, please contact me at (301) 415-2855 or by e-mail at Scott.Wall@nrc.gov.
Sincerely,
/RA/
Scott P. Wall, Senior Project Manager Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-454, STN 50-455, STN 50-456, and STN 50-457
Enclosures:
- 1. Proprietary Audit Plan
- 2. Non-Proprietary Audit Plan cc: Listserv
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION ENCLOSURE 2 REGULATORY AUDIT PLAN REGARDING LICENSE AMENDMENT REQUEST TO MODIFY METHODOLOGY SUPPORTING UTILIZING FRAMATOME GAIA FUEL BRAIDWOOD STATION, UNITS 1 AND 2, AND BYRON STATION, UNIT NOS. 1 AND 2 CONSTELLATION ENERGY GENERATION, LLC.
DOCKET NOS. STN 50-454, STN 50-455, STN 50-456, AND STN 50-457 (NON-PROPRIETARY)
This document contains proprietary information pursuant to Section 2.390 of Title 10 of the Code of Federal Regulations Proprietary information is identified by text enclosed within double brackets.
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION REGULATORY AUDIT PLAN BY THE OFFICE OF NUCLEAR REACTOR REGULATION TO TRANSITION TO FRAMATOME GAIA FUEL CONSTELLATION ENERGY GENERATION, LLC.
BRAIDWOOD STATION, UNITS 1 AND 2 BYRON STATION, UNIT NOS. 1 AND 2 CONSTELLATION ENERGY GENERATION, LLC.
DOCKET NOS. STN 50-454, STN 50-455, STN 50-456, AND STN 50-457
1.0 BACKGROUND
By letter dated November 12, 2025 (Agencywide Documents Access and Management System (ADAMS) Package Accession No. ML25318B206), Constellation Energy Generation, LLC (Constellation, the licensee), submitted a license amendment request (LAR) for Braidwood Station, Units 1 and 2 (Braidwood), and Byron Station, Unit Nos. 1 and 2 (Byron). Specifically, the proposed LAR would modify the methodology previously approved for Braidwood and Byron to transition to Framatome GAIA fuel.
The staff from the Nuclear Regulatory Commissions (NRC), Office of Nuclear Reactor Regulation (NRR) has initiated its review of the LAR in accordance with NRR Office Instruction LIC-101, License Amendment Review Procedures (ML19248C539).
2.0.
REGULATORY AUDIT BASES A regulatory audit is a planned license-or regulation-related activity that includes the examination and evaluation of primarily non-docketed information associated with the LAR. An audit is conducted to gain understanding, to verify information, and to identify information that will require docketing to support the basis of a licensing or regulatory decision. An audit will assist the NRC staff in efficiently conducting its review and gaining insights to the licensees processes and procedures. Information that the NRC staff relies upon to make the safety determination must be submitted on the docket. This audit will be conducted in accordance with NRR Office Instruction LIC-111, Regulatory Audits Revision 1, dated October 2019 (ML19226A274), with exceptions noted within this audit plan.
The NRC staff performs the audit to support its evaluation of whether the licensees LAR can be approved per Title 10 of the Code of Federal Regulations (10 CFR), Section 50.90, Application for amendment of license, construction permit, or early site permit. An audit was determined to be the most efficient approach toward a timely resolution of questions associated with this LAR review because the NRC staff will have an opportunity to minimize the potential for requests for additional information (RAIs) and ensure no unnecessary burden will be imposed by requiring the licensee to address issues that are no longer necessary to make a safety determination.
The NRC staff is requesting an initial set of internal licensee information to be audited by the staff using an online reference portal. Upon completion of this audit, the NRC staff is expected
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION to achieve the following.
- 1.
Confirm internal licensee information that supports statements made in the LAR.
- 2.
Determine whether the information included in the documents is necessary to be submitted to support a safety conclusion.
The audit information the NRC staff determines to be necessary to support the development of the NRC staffs safety evaluation will be requested to be submitted on the docket.
3.0 REGULATORY AUDIT SCOPE AND METHODOLOGY The purpose of the remote audit is to gain a more detailed understanding of the information supporting the licensees request to modify the methodology previously approved for Braidwood and Byron to transition to Framatome GAIA fuel.
4.0 INFORMATION AND OTHER MATERIAL NECESSARY FOR THE AUDIT The NRC staff requests information and audit meeting(s) throughout the audit period. The NRC staff uses an audit items list to identify the information (e.g., methodology, process information, and calculations) to be audited. The NRC staff provides the final audit items list as an enclosure to the audit summary report, which will be publicly available. The attachment to this audit plan includes the initial audit items list. Throughout the audit period, the NRC staff provides the licensee with audit questions and audit-related requests so that the licensee can better prepare for audit discussions with NRC staff. Any information accessed through the licensees portal is not held or retained in any way by NRC staff. The NRC staff requests the licensee to have the requested audit information listed in the audit items list to be readily available and accessible for the NRC staffs review via a Web-based portal.
5.0 TEAM ASSIGNMENTS The audit team will consist of the following NRC staff from NRR.
Scott Wall, Plant Licensing Branch III (LPL3)
Kevin Heller, Nuclear Methods and Fuel Analysis Branch (SFNB)
Robert Beaton, Nuclear Systems Performance Branch (SNSB)
The NRC staff may request access for additional staff as the audit progresses.
6.0 LOGISTICS To support the review schedule communicated to the licensee when the NRC staff accepted the LAR for technical review, audit activities will be performed remotely and virtually using Microsoft Teams, teleconference, and a Web-based portal or other virtual meeting space created by the licensee. NRC information requests and communications with licensee staff is coordinated through the NRCs licensing project manager.
A desktop audit will take place between December 4, 2025, through February 28, 2026. The NRCs licensing project manager informs the licensee of the entrance and exit meeting dates
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION when they are established. The NRC intends to set up audit meeting(s) (e.g., a single, multi-day audit meeting; periodic audit meetings throughout the audit period) on mutually agreeable dates and times (to be determined) to discuss information needs and questions arising from the NRCs review of the audited items. The NRC staff may change and/or add audit dates and times when deemed necessary. Audit meeting agenda and questions will be sent in advance of the audit meeting.
The NRC staff requests the licensee to have the information referenced in Section 4.0 of this audit plan available and accessible for the NRC staffs review via an internet-based portal as soon as reasonably possible. The NRC staff requests that any supplemental information requested be available and accessible for the NRC staffs review within 1 week of the date of the NRCs notification to the licensee of the new requests. The NRCs licensing project manager informs the licensee via routine communications when the NRC staff no longer needs access to the portal. The NRC staff requests the licensee to notify the NRC licensing project manager when an audit item is added to its portal by sending an e-mail to the NRC licensing project manager.
7.0 SPECIAL REQUESTS The NRC requests access to requested documents and information through a Web-based portal that allows the NRC staff to access documents over the Internet. The following conditions associated with the online portal must be maintained while the NRC staff have access to the online portal:
The online portal will be password protected. A separate password will be assigned to each member of the NRC staff taking part in the audit.
The online portal will prevent the NRC participants from printing, saving, downloading, or collecting any information directly from the online portal.
Conditions of use of the online portal will be displayed on the login screen and will require acknowledgment by each user.
Username and password and/or other Web-based portal access information should be provided directly to members of the NRC staff as needed. The NRC licensing project manager will provide the licensee with names and contact information of the NRC staff participating in the audit. All other communications should be coordinated through the NRC project manager.
8.0 DELIVERABLES The NRC staff will develop any RAIs, as needed, via NRR Office Instruction LIC-115 and issue such RAIs separately from audit-related correspondence. The NRC staff will issue an audit summary report prior to completing its review of the LAR.
Attachments:
- 1. Audit Items list
- 2. Audit Questions
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Initial Audit Items List Item #
Audit Item 1
The submittal mentions ((
)) for the Key Parameter sampling strategy. However, no discussion is provided detailing the nature of the ((
)). Please provide this information for the NRC staff to examine.
2 Documentation supporting Audit Question 1 and 3.
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION AUDIT QUESTIONS REGARDING LICENSE ADMENTMENT REQUEST TO TRANSITION TO FRAMATOME GAIA FUEL CONSTELLATION ENERGY GENERATION, LLC BRAIDWOOD STATION, UNITS 1 AND 2 BYRON STATION, UNIT NOS. 1 AND 2 CONSTELLATION ENERGY GENERATION, LLC.
DOCKET NOS. STN 50-454, STN 50-455, STN 50-456, AND STN 50-457
1.0 BACKGROUND
By letter dated November 12, 2025 (Agencywide Documents Access and Management System (ADAMS) Package Accession No. ML25318B206), Constellation Energy Generation, LLC (Constellation, the licensee), submitted a license amendment request (LAR) for Braidwood Station, Units 1 and 2 (Braidwood), and Byron Station, Unit Nos. 1 and 2 (Byron). Specifically, the proposed LAR would modify the methodology previously approved for Braidwood and Byron to transition to Framatome GAIA fuel.
The U.S. Nuclear Regulatory Commission (NRC) staff has identified the need for a regulatory audit to examine the licensees non-docketed information with the intent to gain understanding, to verify information, or to identify information that will require docketing to support the basis of the licensing or regulatory decision. The staff is providing the questions below to aid discussion during the audit.
2.0 AUDIT QUESTIONS
- 1. The sensitivity results provided in the submittal were generated using the Braidwood, Unit 1 model and demonstrate the impact on margin for that unit. However, differences exist between the Unit 1 and Unit 2 steam generators.
- a. Describe the key differences between the steam generator designs and how these differences may have changed the modeling approach of both units within the ARITA methodology (e.g., were different nodalization schemes required or were different operating conditions introduced?)
- b. Describe the applicability of the sensitivity results generated for Unit 1 to Unit 2 (e.g.,
generic applicability and/or scaling applicability) and whether the modeling differences may affect the conclusion of applicability.
OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION
- 2. The primary driver for requesting a change to ((
)), per the submittal, appears to be ((
)). In a clarification call conducted on December 4, 2025, Framatome indicated that for both Braidwood, Unit 1 and Unit 2, when ((
)) were utilized that did not introduce ((
)), similar results were obtained for each unit, demonstrating no significant influence on calculated safety margins. The NRC staff noted; however, that ((
)). Therefore, the NRC staff would like to have a clarification discussion with Framatome to better understand the origin and nature of ((
)), in order to ensure that the comparisons between Unit 1 and Unit 2 are representative of physical phenomena and not artifacts of the constraints imposed on the calculations.
- 3. Regarding the Key Parameter sampling strategy, the submittal indicates the proposed approach of ((
)). Generally, the ((
)). The NRC staff would like to discuss the proposed approach and examine documentation supporting it.
In particular:
- a. Justification that the ((
)) ensures the continued ((
)).
- b. Whether any comparisons have been made between the existing identified ((
)) from the recent Braidwood and Byron LAR adopting the ARITA methodology and the proposed approach.
ML25342A117 (Package)
ML25342A112 (Proprietary)
ML25342A113 (Non-Proprietary)
OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DSS/SFNB/BC NAME SWall SLent SKrepel DATE 12/10/2025 12/11/2025 12/11/2025 OFFICE NRR/DSS/SNSB/BC NRR/DORL/LPL3/BC (A)
NRR/DORL/LPL3/PM NAME NDifrancesco IBerrios SWall DATE 12/12/2025 12/15/2025 12/15/2025