ML23226A005
| ML23226A005 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/26/2023 |
| From: | Richard Guzman NRC/NRR/DORL/LPL1 |
| To: | Carr E Dominion Energy Nuclear Connecticut |
| References | |
| EPID L-2022-LLA-0196 | |
| Download: ML23226A005 (1) | |
Text
September 26, 2023 Mr. Eric S. Carr President - Nuclear Operations and Chief Nuclear Officer Dominion Energy Nuclear Connecticut, Inc.
Millstone Power Station Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711
SUBJECT:
MILLSTONE POWER STATION, UNIT NO. 3 ISSUANCE OF AMENDMENT NO. 287 RE: SUPPLEMENT TO SPENT FUEL POOL CRITICALITY SAFETY ANALYSIS (EPID L-2022-LLA-0196)
Dear Mr. Carr:
The U.S. Nuclear Regulatory Commission (the Commission) has issued the enclosed Amendment No. 287 to Renewed Facility Operating License No. NPF-49 for the Millstone Power Station, Unit No. 3 (Millstone 3), in response to your application dated December 28, 2022.
The amendment supplements a portion of the current nuclear criticality safety analysis for the Millstone 3 spent fuel pool and would allow Dominion Energy Nuclear Connecticut, Inc. to store a new fuel design, GAIA, containing gadolinia, a neutron burnable poison, in the Millstone 3 spent fuel pool storage racks. This supplement is an extension of the burnup credit analysis provided in the letter dated May 3, 2018.
E. Carr A copy of the related safety evaluation is also enclosed. The Commissions monthly Federal Register notice will include the Notice of Issuance.
Sincerely,
/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
Enclosures:
- 1. Amendment No. 287 to NPF-49
- 2. Safety Evaluation cc: Listserv DOMINION ENERGY NUCLEAR CONNECTICUT, INC., ET AL DOCKET NO. 50-423 MILLSTONE POWER STATION, UNIT NO. 3 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 287 Renewed License No. NPF-49 1.
The U.S. Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Dominion Energy Nuclear Connecticut, Inc.
(DENC, the licensee), dated December 28, 2022, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations set forth in 10 CFR Chapter I; B.
The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C.
There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commissions regulations; D.
The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.
The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commissions regulations, and all applicable requirements have been satisfied.
- 2.
Accordingly, paragraph 2.C.(2) of Renewed Facility Operating License No. NPF-49 is hereby amended to read as follows:
(2)
Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 287 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto are hereby incorporated into the license. DENC shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.
- 3.
This license amendment is effective as of the date of issuance and shall be implemented within 60 days of issuance.
FOR THE NUCLEAR REGULATORY COMMISSION Hipólito J. González, Chief Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
Attachment:
Changes to the Renewed Facility Operating License Date of Issuance: September 26, 2023 Hipolito J.
Gonzalez Digitally signed by Hipolito J. Gonzalez Date: 2023.09.26 13:32:00 -04'00'
ATTACHMENT TO LICENSE AMENDMENT NO. 287 MILLSTONE POWER STATION, UNIT NO. 3 RENEWED FACILITY OPERATING LICENSE NO. NPF-49 DOCKET NO. 50-423 Replace the following page of the Renewed Facility Operating License with the attached revised page. The revised page is identified by amendment number and contains a marginal line indicating the area of change.
Remove Insert 4
4
(2)
Technical Specifications The Technical Specifications contained in Appendix A, revised through Amendment No. 287 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto are hereby incorporated into the license. DENC shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.
(3)
DENC shall not take any action that would cause Dominion Energy, Inc.
or its parent companies to void, cancel, or diminish DENC's Commitment to have sufficient funds available to fund an extended plant shutdown as represented in the application for approval of the transfer of the licenses for MPS Unit No. 3.
(4)
Immediately after the transfer of interests in MPS Unit No. 3 to DNC*, the amount in the decommissioning trust fund for MPS Unit No. 3 must, with respect to the interest in MPS Unit No. 3, that DNC* would then hold, be at a level no less than the formula amount under 10 CFR 50.75.
(5)
The decommissioning trust agreement for MPS Unit No. 3 at the time the transfer of the unit to DNC* is effected and thereafter is subject to the following:
(a)
The decommissioning trust agreement must be in a form acceptable to the NRC.
(b)
With respect to the decommissioning trust fund, investments in the securities or other obligations of Dominion Energy, Inc. or its affiliates or subsidiaries, successors, or assigns are prohibited.
Except for investments tied to market indexes or other non-nuclear-sector mutual funds, investments in any entity owning one or more nuclear power plants are prohibited.
(c)
The decommissioning trust agreement for MPS Unit No. 3 must provide that no disbursements or payments from the trust, other than for ordinary administrative expenses, shall be made by the trustee until the trustee has first given the Director of the Office of Nuclear Reactor Regulation 30 days prior written notice of payment. The decommissioning trust agreement shall further contain a provision that no disbursements or payments from the trust shall be made if the trustee receives prior written notice of objection from the NRC.
(d)
The decommissioning trust agreement must provide that the agreement cannot be amended in any material respect without 30 days prior written notification to the Director of the Office of Nuclear Reactor Regulation.
- On May 12, 2017, the name Dominion Nuclear Connecticut, Inc. changed to Dominion Energy Nuclear Connecticut, Inc.
Renewed License No. NPF-49 Amendment No. 270-286, 287
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 287 TO RENEWED FACILITY OPERATING LICENSE NO. NPF-49 DOMINION ENERGY NUCLEAR CONNECTICUT, INC., ET AL MILLSTONE POWER STATION, UNIT NO. 3 DOCKET NO. 50-423
1.0 INTRODUCTION
By letter dated December 28, 2022 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22362A102), Dominion Energy Nuclear Connecticut, Inc. (the licensee) submitted a license amendment request (LAR) to supplement a portion of the current nuclear criticality safety (NCS) analysis for the Millstone Unit 3 (Millstone 3) spent fuel pool (SFP). The proposed license amendment does not contain any changes to the Millstone 3 Technical Specifications. The proposed amendment would allow the licensee to store a new fuel design, GAIA, containing gadolinia, a neutron burnable poison, in the Millstone 3 spent fuel pool storage racks. This supplement is only an extension of the burnup credit analysis provided in the letter dated May 3, 2018 (ML18128A049).
2.0 REGULATORY EVALUATION
The regulatory requirements and guidance documents that the NRC staff used in the review of the LAR are listed below.
Title 10 to the Code of Federal Regulations (10 CFR), Part 50, Appendix A, General Design Criteria for Nuclear Power Plants (GDC) Criterion 62, Prevention of criticality in fuel storage and handling, requires that, Criticality in the fuel storage and handling system shall be prevented by physical systems or processes, preferably by use of geometrically safe configurations.
The regulations in 10 CFR 50.68, Criticality accident requirements, requires, in part, under 10 CFR 50.68(a), each holder of an operating license shall comply with either 10 CFR 70.24 or the requirements in 10 CFR 50.68(b). The licensee has elected to comply with 10 CFR 50.68(b),
which describes the keff limits for the NCS analysis as well as limits on the maximum nominal U-235 enrichment of fresh fuel assemblies to five percent by weight.
The Nuclear Regulatory Commission (NRC) staff review was performed consistent with Section 9.1.1, Criticality Safety of Fresh and Spent Fuel Storage and Handling (ML070570006), and Section 9.1.2, New and Spent Fuel Storage (ML070550057), of NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants.
NEI 12-16, Revision 4, Guidance for Performing Criticality Analyses of Fuel Storage at Light-Water Reactor Power Plants (ML19269E069) provides guidance for acceptable approaches that may be used by industry to perform criticality analyses for the storage of new and spent fuel at light-water reactor power plants in compliance with 10 CFR Part 50. NEI 12-16, Revision 4, was endorsed by the NRC in Regulatory Guide (RG) 1.240, Fresh and Spent Fuel Pool Criticality Analyses (ML20356A127) with some clarifications and exceptions.
NUREG/CR-6801, Recommendations for Addressing Axial Burnup in PWR Burnup Credit Analyses, (ML031110292) which provides analyses related to the reactivity effect of axial burnup profiles.
NUREG/CR-6760, Study of the Effects of Integral Burnable Absorbers for PWR Burnup Credit, (ML020770436) which contains studies related to reactivity effects when depleting fuel with various integral burnable absorbers.
3.0 TECHNICAL EVALUATION
3.1 Background
The licensee has submitted a license amendment request to supplement the burnup credit portion of its SFP criticality analysis of record (AOR) that, if approved, would allow the licensee to store GAIA fuel assemblies containing gadolinia in the Millstone Unit 3 SFP. The current AOR dated May 3, 2018 (ML18128A049), as supplemented by the letters dated November 29, 2018, March 27, 2019, and May 7, 2019 (ML18340A028, ML19092A332, and ML19135A067, respectively) and NRC safety evaluation (SE) (ML19126A000) did not consider the effects of GAIA fuel or gadolinia as a burnable poison in the design basis fuel assembly and burnup credit analysis. Therefore, the licensee has submitted this LAR to supplement the burnup credit portion of the current criticality safety analysis of record (2019) by demonstrating that it bounds the use of gadolinia burnable poison.
3.2 Bounding Fuel Assembly Design Millstone 3 uses a 17x17 lattice fuel with a center instrument tube and 24 guide tubes. Four fuel designs have been used but all designs are similar. The current and legacy fuel designs are listed in Table 3.1 of Attachment 5 to the letter dated May 3, 2018. The licensee has used a composite fuel design intended to represent current and legacy fuel designs. The composite fuel design is described in Table 13.2 of the same attachment. Use of a composite fuel design is an accepted practice to simplify the analysis. The composite fuel design did not originally consider the GAIA assembly design. GAIA is also a 17x17 lattice fuel with very similar characteristics as standard 17x17 PWR fuel. The parameters used to generate the composite fuel assembly bound the parameters of the GAIA assembly.
The NRC staff has determined that the bounding fuel assembly design in the AOR will bound the GAIA assembly design because the GAIA assembly design does not significantly deviate from the characteristics of the current and legacy assemblies described in the AOR that were considered when creating the composite fuel assembly design.
3.3 Burnable Absorbers The licensees AOR considers multiple burnable absorbers, including Pyrex Burnable Poison, Integral Fuel Burnable Absorber (IFBA), and Wet Annular Burnable Absorber (WABA). WABA was used as the bounding burnable absorber in the depletion analysis and is used to develop the burnup curves.
Burnable absorbers can have a significant effect on the SFP keff. Typically, absorbers harden the neutron spectrum resulting in higher reactivity in storage. Therefore, the effects of the most limiting burnable absorbers must be considered in the depletion analysis and used in the nominal case of the SFP criticality analysis. However, gadolinia as a burnable absorber may be analyzed differently than WABA, IFBA, or other burnable absorbers. Instead of displacing water like WABA, gadolinia is integrated into the fuel matrix, thus displacing fuel. As stated in NEI 12-16, it is generally acceptable to neglect the presence of gadolinia in the depletion analysis because the positive reactivity impact is unlikely to be greater than the negative reactivity impact of displacing fuel as long as gadolinia is the only burnable absorber in the assembly and no credit is taken for the reduced UO2 density.
NEI 12-16 states that if multiple burnable absorbers are present in a fuel assembly, the depletion analysis should consider all burnable absorbers present in the assembly over the entire burnup. The licensee indicates in Section 4, Impact on the Criticality Safety Analysis, of to the LAR, that gadolinia will be the sole burnable absorber in GAIA fuel assemblies. Accordingly, the GAIA fuel containing gadolinia stored in the Millstone 3 SFP may only contain gadolinia as a burnable absorber. The staffs review of this LAR was limited to gadolinia as a burnable absorber in the GAIA fuel assembly. Should the licensee need to include other burnable absorbers, such as WABA or IFBA, in addition to gadolinia in GAIA fuel, a separate LAR will be required demonstrating continued compliance with 10 CFR 50.68(b).
The Millstone 3 criticality analysis did not consider the depletion characteristics of gadolinia as a burnable absorber. However, the considerations above are sufficient to qualitatively demonstrate that modeling fuel depletion with unpoisoned fuel rods bounds modeling the same fuel depletion with gadolinia. In the Millstone 3 AOR, it is shown that modeling fuel depletion with maximum WABA loading bounds unpoisoned fuel. Therefore, it can be reasonably assumed the Millstone 3 AOR bounds the depletion of fuel assemblies with gadolinia.
NUREG/CR-6760 contains analyses related to fuel depletion with gadolinium bearing rods in pressurized water reactor (PWR) assemblies. While the fuel assemblies analyzed in the NUREG/CR-6760 may not be the same as those present in the Millstone 3 SFP, the conclusions related to fuel depletion with gadolinium are not expected to deviate significantly from one PWR assembly to another. Namely, the conclusion that the SFP keff of gadolinium bearing rods is always lower when fuel depletion is modeled without gadolinium present than when gadolinium is explicitly modeled is reasonable for the composite fuel assembly in the Millstone 3 AOR.
The NRC staff has determined that the Millstone 3 criticality AOR bounds the use of gadolinia as a burnable absorber because a more limiting burnable absorber loading is assumed, and it has been shown to be conservative to neglect gadolinia during depletion, which is consistent with the guidance of NEI 12-16.
3.4 Axial and Radial Burnup Distributions For gadolinia loading to be bounded under the current NCS AOR, the licensee must also consider the impact on axial and radial burnup distributions. As stated by the licensee in section 4.0 of the LAR, the assumptions used in the NCS analysis for the axial burnup distribution remain applicable and the NUREG/CR-6801 burnup shapes, which are used in the AOR, includes fuel designs using gadolinia. The licensee indicated there are no significant changes expected in fuel management scheme and that gadolinia loading will be symmetric. Therefore, the NRC staff finds the current NCS AOR justifications remain applicable when using gadolinia and the axial burnup distributions assumed in the NCS AOR remain bounding. The NRC staff also finds the licensees radial burnup tilt analysis used in the NCS AOR remains applicable and bounds depletion with gadolinia because NUREG/CR-6801 models consider depletion with gadolinia.
3.5 NRC Staff Conclusion
The proposed change has been evaluated by the NRC staff to determine compliance with applicable regulatory requirements as specified in section 2.0 of this SE.
Based on the evaluation discussed in section 3 of this SE, the NRC staff concludes that there is reasonable assurance that the Millstone 3 NCS AOR will bound the depletion of the GAIA fuel assembly design with gadolinia as the sole burnable absorber and will continue to meet the applicable regulatory requirements of 10 CFR 50.68 and GDC 62.
4.0 STATE CONSULTATION
In accordance with the Commissions regulations, the Connecticut State official was notified of the proposed issuance of the amendment on August 14, 2023. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to the installation or use of facility components located within the restricted area as defined in 10 CFR Part 20, Standards for protection against radiation. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The NRC has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on this finding published in the Federal Register (88 FR 10556; February 21, 2023).
Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that public health and safety will not be endangered by operation in the proposed manner, (2) there is reasonable assurance that such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to public health and safety.
Principal Contributor: B. Wise Date of Issuance: September 26, 2023
ML23226A005 OFFICE NRR/DORL/LPL1/PM NRR/DORL/LPL1/LA NRR/DSS/SFNB/BC NAME RGuzman KEntz SKrepel DATE 8/15/2023 8/15/2023 5/24/2023 OFFICE OGC - NLO NRR/DORL/LPL1/BC NRR/DORL/LPL1/PM NAME MWoods HGonzález RGuzman DATE 9/26/2023 9/26/2023 9/26/2023