ML25197A608
| ML25197A608 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/15/2025 |
| From: | Richard Guzman NRC/NRR/DORL/LPL1 |
| To: | Maynard N Dominion Energy Nuclear Connecticut |
| References | |
| EPID L-2025-LLA-0053 | |
| Download: ML25197A608 (1) | |
Text
From:
Richard Guzman To:
nicholas.d.maynard@dominionenergy.com Cc:
Hipo Gonzalez
Subject:
Millstone Unit 3 Request for Additional Information re: LAR to Revise Selected TSs - Control Building Isolation; Accident Monitoring; Accumulators, RWST; & Secondary Containment SRs (EPID L-2025-LLA-0053)
Date:
Tuesday, July 15, 2025 6:45:25 AM
- Nick, On June 18, 2025, the U.S. Nuclear Regulatory Commission (NRC) staff sent Dominion Energy Nuclear Connecticut, Inc. (the licensee) the subject Request for Additional Information (RAI) as a draft e-mail. This RAI is regarding the licensees March 20, 2025 (ML25079A225), license amendment request to revise the technical specifications (TSs) for Millstone Power Station, Unit 3, related to control building isolation, accident monitoring instrumentation, accumulator and refueling water storage tank boron concentration limits, and secondary containment surveillance requirements.
As discussed with you on July 14, 2025, a clarification call was not necessary as your staff understood the information being requested by the NRC staff in the draft RAI. Updated below is the official (final) RAI. Please respond to this RAI by August 14, 2025, which is approximately 30 days from the date of this e-mail communication. A publicly available version of this message will be placed in ADAMS as an official agency record.
Please contact me if you have any questions regarding this request.
- Thanks, Richard Guzman Sr. PM, Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Office: O-11C21 l Phone: (301) 415-1030 Richard.Guzman@nrc.gov
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REQUEST FOR ADDITIONAL INFORMATION REVIEW OF PROPOSED AMENDMENT TO REVISE TSs RELATED TO CONTROL BUILDING ISOLATION, ACCIDENT MONITORING INSTRUMENTATION,
ACCUMULATOR AND REFUELING WATER STORAGE TANK BORON CONCENTRATION LIMITS, AND SECONDARY CONTAIMENT SUREVEILLANCE REQUIREMENTS DOMINION ENERGY NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3 DOCKET NO. 50-423 (EPID: L-2025-LLA-0053)
INTRODUCTION By letter dated March 20, 2025 (ADAMS Accession No. ML25079A225), Dominion Energy Nuclear Connecticut, Inc. (the licensee) submitted a license amendment request (LAR) to revise the technical specifications (TSs) for Millstone Power Station, Unit No. 3 (MPS3).
The proposed TS changes include the relocation of the boron concentration limits in TS Limiting Condition for Operation (LCO) 3.5.1 (Accumulators) and TS LCO 3.5.4 (Refueling Water Storage Tanks (RWST)) to the Core Operating Limit Report (COLR), and addition of TS 3.5.1 and TS 3.5.4 in MPS3 TSs 6.9.1.6.a and 6.9.1.6.b for the applicable methodologies to establish the core operating limits included in the COLR for accumulators and RWST boron concentration limits.
The Nuclear Regulatory Commission (NRC) staff is reviewing the LAR and determined that the following request for additional information (RAI) is necessary for the staff to complete its review.
REGULATORY BASIS The regulatory requirements and guidance on which the NRC staff based its evaluation are:
In the regulation at Title 10 of the Code of Federal Regulations (10 CFR), Section 50.34, "Contents of application; technical information," the NRC established its regulatory requirements that safety analysis reports analyze the design and performance of structures, systems, and components provided for the prevention of accidents and the mitigation of the consequences of accidents. As part of the core reload process, licensees perform reload safety evaluations to ensure that their safety analyses remain bounding for the design cycle. To confirm that the analyses remain bounding, licensees confirm that the inputs to the safety analyses are conservative with respect to the current design cycle. These inputs are checked using analytical models, and if key safety analysis parameters are not bounded, further analysis of the affected transients or accidents is performed to ensure that the applicable acceptance criteria are satisfied.
In 10 CFR 50.36, the NRC established its regulatory requirements related to the content of TSs. The regulation at 10 CFR 50.36(a)(1) states that a summary statement of the bases or reasons for such specifications shall also be included in the application but shall not become part of the TSs. Paragraph 10 CFR 50.36(b) requires that TSs will be derived from the analyses and evaluations included in the
safety analysis report, and amendments thereto. The categories of items required to be in the TSs are provided 10 CFR 50.36(c). As required by 10 CFR 50.36(c)(2)(i),
the TSs will include LCOs, which are the lowest functional capability or performance levels of equipment required for safe operation of the facility. Per 10 CFR 50.36(c)(2)
(i), when an LCO of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the TSs until the condition can be met. Paragraph 10 CFR 50.36(c)(2)(ii)(B) Criterion 2 requires that an LCO be established for: "A process variable design feature or operating restriction that is an initial condition or a design-basis accident or transient analysis that either assumes the failure of or presents a challenge to the integrity of a fission product barrier."
Paragraph 10 CFR 50.36(c)(5), "Administrative controls," are the provisions relating to organization and management, procedures, recordkeeping, review and audit, and reporting necessary to assure operation of the facility in a safe manner.
In addition to the above regulatory requirements, the following guidance documents were considered in the NRC staffs evaluation:
NUREG-0800, Standard Review Plan, Section 16, Revision 3.0, "Technical Specifications;" and Generic Letter (GL) 88-16, Removal of Cycle-Specific Parameter Limits from Technical Specifications, provides guidance by which the values of certain parameters could be determined and modified on a cycle-specific basis without NRC prior NRC review and approval. To implement this guidance, licensees are required to do the following: (1) use NRC-approved methodology to determine operating limits; (2) include a list in the TS Administrative Controls section of the references used to determine the operating limits; and (3) maintain the limits in a COLR, which must be submitted to the NRC for information.
REQUEST FOR ADDITIONAL INFORMATION RAI-1 Methodology for Determining the Boron Concentration Limits in Accumulators and RWST The licensee indicates on page 16 of 25 of Attachment 1 to the LAR that the methodology documented in the NRC-approved topical report (TR) VEP-FRD-42-A, Revision 2, is applicable for use in determining the boron concentration limits in accumulators and RWST.
As indicated on page 9 of the NRC staffs safety evaluation (ML031621014), the TR safety evaluation report (SER) approved the use of VEP-FRD-42, specifically for Westinghouse and Framatome ANP Advanced Mark-BW fuel. Accordingly, the NRC placed the following Condition and Limitation upon VEP-FRD-42:
Prior to the use of the Topical Report VEP-FRD-42, Revision 2, methodology for fuel types other than Westinghouse and Framatome ANP Advanced Mark-BW fuel, VEPCO must confirm that the impact of the fuel design and its specific features can be accurately modeled with the VEPCO nuclear design and safety analysis codes and methods as discussed in its submittal dated
May 13, 2002. Should the changes necessary to accommodate another fuel product require changes to the reload methodology of Topical Report VEP-FRD-42, Revision 2, these proposed changes are required to be submitted for prior NRC review and approval.
Clarify if there are fuel types other than Framatome ANP Advanced Mark-BW and Westinghouse fuel (such as GAIA fuel) to be installed in the MPS3 core for this application and describe how those fuel types comply with the Condition and Limitation of VEP-FRD-42 cited above.
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From: Richard Guzman <Richard.Guzman@nrc.gov>
Sent: Wednesday, June 18, 2025 7:59 AM To: nicholas.d.maynard@dominionenergy.com
Subject:
Millstone Unit 3 - DRAFT Request for Additional Information, LAR to Revise Selected TSs Re:
Control Building Isolation; Accident Monitoring; Accumulators, RWST; & Secondary Containment SRs (EPID L-2025-LLA-0053)
- Nick, By letter dated March 20, 2025 (ADAMS Accession No. ML25079A225), Dominion Energy Nuclear Connecticut, Inc. (the licensee) submitted a license amendment request (LAR) to revise the Millstone Power Station, Unit No. 3, Technical Specifications (TSs) related to control building isolation, accident monitoring instrumentation, accumulator and refueling water storage tank boron concentration limits, and secondary containment surveillance requirements.
The NRC staff has determined that additional information is needed to complete its review, as described in the request for additional information (RAI) shown below. This RAI is identified as DRAFT at this time to confirm your understanding of the information needed by the NRC staff to complete its evaluation. Please let me know your groups availability for a clarification call if desired, and I will coordinate availabilities w/the NRC technical staff.
- Thanks, Rich Guzman Sr. PM, Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Phone: (301) 415-1030 Richard.Guzman@nrc.gov