ML25231A302
| ML25231A302 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 08/26/2025 |
| From: | Richard Guzman NRC/NRR/DORL/LPL1 |
| To: | Carr E Dominion Energy Nuclear Connecticut |
| References | |
| EPID L-2025-LRM-0077 | |
| Download: ML25231A302 (1) | |
Text
August 26, 2025 LICENSEE:
Dominion Energy Nuclear Connecticut, Inc.
FACILITY:
Millstone Power Station, Unit No. 3
SUBJECT:
SUMMARY
OF JULY 17, 2025, PRE-SUBMITTAL PUBLIC MEETING WITH DOMINION ENERGY NUCLEAR CONNECTICUT, INC. TO DISCUSS FUTURE AMENDMENT ON MILLSTONE POWER STATION, UNIT NO. 3 - NEW FUEL STORAGE AND SPENT FUEL POOL CRITICALITY SAFETY ANALYSIS (EPID L-2025-LRM-0077)
On July 17, 2025, a hybrid observation public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) staff and representatives of Dominion Energy Nuclear Connecticut, Inc. (DENC or the licensee). The purpose of the meeting was to discuss the future license amendment request (LAR) to modify the new fuel storage and spent fuel pool criticality safety analysis for the Millstone Power Station, Unit No. 3 (MPS3). The meeting notice and agenda, dated July 8, 2025, are available in the NRCs Agencywide Documents Access and Management System (ADAMS) at Accession No. ML25189A446. The enclosure to this summary contains a list of attendees.
The licensee presented information from their presentation slides (ML25188A265), providing an overview of the expected changes to the new fuel storage and spent fuel pool criticality safety analysis and associated technical specifications (TS) to support a transition from 18-month to 24-month fuel cycles. As part of this transition, the licensee plans to increase the maximum fuel enrichment to 6.5 weight percent, with a maximum credited burnup of approximately 60 gigawatt-days per metric ton of uranium. The associated fuel assembly modifications will consist primarily of slightly larger fuel pellets, increased fuel density, and the use of advanced zirconium cladding material. No changes are proposed for storage racks.
The NRC staff and DENC representatives discussed the following notable items:
Regarding the licensee's proposed submission and implementation schedule, the licensee plans to submit the proposed LAR by June 2026, with the goal of obtaining NRC approval by December 2027 and implementation of the amendment in spring 2028.
In response to the NRC staff's inquiry about the requested approval date, the licensee clarified the timeline for fuel procurement. The licensee would plan to have fuel on-site by February or March 2028 and would place the order approximately nine months prior, around May or June 2027. The licensee acknowledged potential risks associated with the proposed schedule and intends to confirm that the NRC's review is progressing without significant technical concerns or issues before proceeding with the fuel order in mid-2027.
The licensee presented a description of the current configurations of the spent fuel pool regions, new fuel storage racks, and the associated proposed changes for each.
Regarding the licensees changes to the new fuel storage racks, the NRC staff inquired about the inclusion of both Gadolinium (Gad) and Integral Fuel Burnable Absorber (IFBA) in the same fuel assembly, noting that it is uncommon for licensees to use both together. The licensee explained that they plan to incorporate both options into the TSs to maintain flexibility. They clarified that their proposed analysis does not exclude the possibility of combining Gad and IFBA in a single fuel assembly. The NRC staff pointed out that from a core design perspective, incorporating both Gad and IFBA in the same fuel assembly would be a unique approach and would require a first-of-a-kind review, particularly in relation to fuel depletion aspects. The licensee acknowledged the potential complexity of this analysis and the staff's review process and indicated their willingness to engage in a follow-up pre-submittal discussion if needed. The licensee outlined their general approach, which would involve presenting the minimum Gad and IFBA loading requirements through step changes in case-level format, as part of their proposed LAR.
The licensee also recognized the expectation to provide a higher level of detail and technical justification to support this potentially complex review.
The licensee outlined its plans for implementing the proposed TS changes as part of the transition to a 24-month fuel cycle. Once the transition is complete, the new TS will apply as additional 24-month fuel is stored in Region 3. Region 3's spent fuel pool consists of 6x6 rack modules, and for the transition, four specific cells in each 6x6 module will need to remain empty. The licensee intends to transition one rack module at a time. The NRC staff emphasized that the analysis must account for the spacing between existing rack modules and incorporate seismic considerations. The NRC staff noted that the proposed TS changes will involve a mixture of current and new requirements, with the number of rack modules subject to the old requirements gradually decreasing over time, while the number subject to the new requirements will increase. This process will continue until the old requirements are phased out and replaced entirely by the new ones. DENC acknowledged that presenting this transition analysis will be complex and require detailed documentation. Additionally, the proposed TS will need to clearly delineate the associated transitions. Criticality analysis will also be necessary to address the mixing of old and new requirements over time. The licensee agreed that an interface or transition analysis will be required to ensure that proper controls are in place for the implementation of TS throughout the transition period.
The licensee presented key components of its proposed analysis, including the list of criticality computer codes and the associated code benchmarks used in support of the criticality safety analysis. These benchmarks account for higher fuel enrichments, modified fuel densities, and advanced cladding materials. The NRC staff noted that the licensees Standardized Computer Analyses for Licensing Evaluation (SCALE) code benchmarks appropriately encompass the scope of the proposed changes to the spent fuel pool.
The licensee presented certain components of its proposed analysis, including the list of criticality computer codes and code benchmarks used for the criticality safety analysis based on the higher fuel enrichment, changed densities, and advanced cladding adjustments. The NRC staff commented that the licensees criticality code benchmarks for SCALE are inclusive of the scope of what the licensee is proposing to change in the spent fuel pool. The licensee is also proposing a composite bounding assembly model.
The licensee stated that they will simplify their model by representing the fuel assembly grids as water, in accordance with Nuclear Energy Institute (NEI) guidance, NEI 12-16.
In response to the NRC staffs inquiry regarding this grid modeling approach, particularly considering the potential for maximum soluble boron concentrations to approach the TS limit, the licensee explained that their analysis credits 50 ppm of soluble boron below the TS limit. They indicated that they are observing sufficient margin on the k-effective side (i.e., the calculated k-effective remains very low), rather than relying solely on margins associated with the maximum soluble boron concentration.
The licensee stated that it intends to submit the proposed LAR by June 2026 and is open to conducting a follow-on pre-application meeting with the staff to provide any significant updates prior to submission.
Members of the public were not in attendance. No regulatory decisions or commitments were made at the meeting. Public Meeting Feedback forms were not received.
If you have any questions, please contact the Millstone project manager, Theo Edwards, at 301-415-1721 or by email to Theo.Edwards@nrc.gov.
/RA/
Richard V. Guzman, Senior Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-423
Enclosure:
List of Attendees cc: Listserv
ML25231A302 NRC-001 OFFICE NRR/DORL/LPL1/PM NRR/DORL/LPL1/LA NRR/DORL/LPL1/BC NAME TEdwards (RGuzman for)
KEntz HGonzález DATE 08/20/2025 08/25/2025 08/26/2025 OFFICE NRR/DORL/LPL1/PM NAME RGuzman DATE 08/26/2025
Enclosure LIST OF ATTENDEES
SUMMARY
OF JULY 17, 2025, PRE-SUBMITTAL PUBLIC MEETING WITH DOMINION ENERGY NUCLEAR CONNECTICUT, INC.
TO DISCUSS FUTURE AMENDMENT ON NEW FUEL STORAGE AND SPENT FUEL POOL CRITICAILITY SAFETY ANALYSIS ATTENDEES ORGANIZATION Richard Guzman U.S. Nuclear Regulatory Commission (NRC)
Kent Wood NRC Kevin Heller NRC Jack Vande Polder NRC Theo Edwards NRC John Klos NRC Reena Boruk NRC Steve Smith NRC Shivani Mehta NRC Matt Yoder*
NRC Nick Maynard Dominion Energy Nuclear Connecticut, Inc. (DENC)
Brian Vitiello DENC Kasey Kennett DENC Jared Cantrell DENC Tom Psuik*
DENC Shayan Sinha*
DENC Ryan Magruder*
DENC Bob Reynold*
Duke Energy Carolinas, LLC (Duke)
Dave Orr*
Duke Larry James*
Duke Andrea Jennetta*
S&P Global Platts
- Participated remotely via Microsoft Teams audio-video conferencing