NL-25-0318, Response to NRC Requests Regarding Emergency License Amendment Request One-Time Change to Technical Specification 3.5.2, Core Makeup Tanks (Cmts) - Operating
| ML25224A262 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 08/12/2025 |
| From: | Coleman J Southern Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NL-25-0318 | |
| Download: ML25224A262 (1) | |
Text
3535 Colonnade Parkway Birmingham, AL 35243 Tel. 205.992.5000 Regulatory Affairs August 12, 2025 Docket No.:
52-026 NL-25-0318 10 CFR 50.90 10 CFR 50.91(a)(5)
U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Southern Nuclear Operating Company Vogtle Electric Generating Plant Unit 4 Response to NRC Requests Regarding Emergency License Amendment Request One-Time Change to Technical Specification 3.5.2, Core Makeup Tanks (CMTs) -
Operating Ladies and Gentlemen:
Pursuant to the provisions of 10 CFR 50.90 and 10 CFR 50.91(a)(5), Southern Nuclear Operating Company (SNC) requested an emergency license amendment to Combined License (COL) No. NPF-92 for Vogtle Electric Generating Plant (VEGP) Unit 4. The requested amendment would temporarily revise the COL Appendix A, Technical Specifications (TS) 3.5.2, Core Makeup Tanks (CMTs) - Operating, Surveillance Requirement (SR) 3.5.2.4 to reduce the minimum allowable CMT A boron concentration and to not require performance of SR 3.5.2.4 until startup from the first VEGP Unit 4 refueling outage. On August 12, 2025, the NRC requested confirmatory information and additional information regarding this License Amendment Request.
The Enclosure provides the response to the request. The response does not impact the technical evaluation, regulatory evaluation (including the Significant Hazards Consideration Determination) or environmental considerations for the proposed changes.
This letter contains no regulatory commitments. This letter has been reviewed and determined not to contain security-related information.
In accordance with 10 CFR 50.91, a copy of this application, with enclosures, is being provided to the designated State of Georgia official.
U. S. Nuclear Regulatory Commission NL-25-0318 Page 2 If you have any questions, please contact Mr. Ryan Joyce at (205) 992-6468.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on the 12th day of August 2025.
Respectfully submitted, Jamie M. Coleman Regulatory Affairs Director
Enclosure:
Response to Request for Confirmatory Information and Request for Additional Information cc:
NRC Regional Administrator, Region ll NRR Project Manager - Vogtle 3&4 Senior Resident Inspector - Vogtle 3&4 Director, Environmental Protection Division - State of Georgia Document Services RTYPE: VND.LI.L00 Digitally signed by JAMIEMCO Date: 2025.08.12 18:37:07
-05'00'
ENCLOSURE to NL-25-0318 Response to Request for Confirmatory Information and Request for Additional Information Emergency License Amendment Request: One-Time Change to Technical Specification 3.5.2, Core Makeup Tanks (CMTs) - Operating
Enclosure to NL-25-0318 Response to Request for Confirmatory Information and Request for Additional Information E-1 On August 12, 2025, the NRC provided the following request for confirmatory information and additional information.
REQUEST FOR CONFIRMATORY INFORMATION (RCI) AND REQUEST FOR ADDITIONAL INFORMATION (RAI) QUESTIONS By letter dated August 11, 2025 (Agencywide Documents Access and Management System Accession No. ML25136A392), Southern Nuclear Operating Company (SNC, the licensee) requested that the U.S. Nuclear Regulatory Commission (NRC) amend Vogtle Electric Generating Plant (Vogtle), Unit 4, Combined License (COL) Number NPF-92.
The proposed license amendment request (LAR) revises Technical Specifications (TS) 3.5.2, Core Makeup Tanks (CMTs) - Operating, to add a note to the Limiting Condition for Operation (LCO) and another note in Surveillance Requirement (SR) 3.5.2.4 regarding boron concentration as well as editorial changes. The proposed LAR temporarily revises the TS 3.5.2 to reduce the minimum allowable CMT A boron concentration and to not require performance of SR 3.5.2.4 until startup from the first Vogtle, Unit 4, refueling outage (RFO), which is scheduled for the fall of 2025. The proposed LAR is a one-time temporary change, and the proposed LAR would be effective until startup from the first Vogtle, Unit 4, RFO.
The proposed LAR was submitted under emergency circumstances as described in the provisions of paragraph 50.91(a)(5) of Title 10 of the Code of Federal Regulations due to the time critical nature of the LAR.
The U.S. Nuclear Regulatory Commission (NRC) staff has determined that additional information is required for the staff to complete its review.
Request for Confirmatory Information:
The regulation in 10 CFR 50.91(a)(5) state, in part, that:
(5) Where the Commission finds that an emergency situation exists, in that failure to act in a timely way would result in derating or shutdown of a nuclear power plant, or in prevention of either resumption of operation or of increase in power output up to the plant's licensed power level, it may issue a license amendment involving no significant hazards consideration without prior notice and opportunity for a hearing or for public commentThe Commission expects its licensees to apply for license amendments in timely fashionWhenever an emergency situation exists, a licensee requesting an amendment must explain why this emergency situation occurred and why it could not avoid this situation, and the Commission will assess the licensee's reasons for failing to file an application sufficiently in advance of that event.
During the pre-submittal meeting on August 11, 2025, the licensee stated that the leaking valve condition had existed since the summer of 2024 and that a maintenance outage was conducted in March 2025.
Please confirm that the March 2025 outage was of insufficient length and scope for repairs to the leaking valves for CMT A to have been repaired before resuming power operation and that licensee actions could not have avoided the need for an emergency amendment.
Enclosure to NL-25-0318 Response to Request for Confirmatory Information and Request for Additional Information E-2 Response to Request for Confirmatory Information:
While the Unit 4 maintenance outage length would not have challenged affecting repairs, the maintenance outage included limited scope and did not include repair of CMT A outlet valves.
The valve repairs are in scope for the upcoming refueling outage (4R01). The outlet valve repairs were not included in the maintenance outage scope because CMT A boron concentration was being successfully managed through boron additions. In addition, the site did not have all the parts needed to be able to repair both of the valves at the time of the maintenance outage.
Request for Additional Information #1 On August 8, 2025, sampling analysis indicated less than the 3400 ppm boron concentration required by TS SR 3.5.2.4. During the pre-submittal meeting on August 11, 2025, the licensee told the NRC that CMT A was declared inoperable and actions were taken to address increase the boron concentration such that Vogtle Unit 4 exited the 72-hour LCO Completion Time on August 9, 2025.
Please describe why boron cannot be added in a similar manner to preclude a similar entry into the LCO as boron continues to deplete during the remainder of the operating cycle and coast down to refueling.
Response to Request for Additional Information #1:
Adding sufficient boric acid to maintain CMT A boron concentration above the minimum Technical Specification (TS) limit of 3400 ppm is not possible due to the characteristics of an end-of-life core combined with the observed valve leakage. The negative reactivity that results from adding boric acid is unable to be counteracted by diluting the Reactor Coolant System (RCS) due to the low boron concentration without performing a significant derate.
Request for Additional Information #2:
During the pre-submittal meeting and the written submittal dated August 11, 2025, the licensee proposes not to perform any boron concentration sampling of the CMT prior to entry into TS 3.5.3, Core Makeup Tanks (CMTs) - Shutdown, Reactor Coolant System (RCS) Intact, for Vogtle, Unit 4, refueling outage.
Please describe the analytical methods used to determine boron concentration to meet proposed TS 3.5.2, Core Makeup Tanks (CMTs) - Operating, for the remainder of the current operating cycle. Also, please provide the results for each monthly test and evaluation since CMT A leakage was first identified in the summer of 2024 including:
the results of 31-day boron concentration sampling to meet TS SR 3.5.2.4, and CMT A leakage rate trending.
Enclosure to NL-25-0318 Response to Request for Confirmatory Information and Request for Additional Information E-3 Response to Request for Additional Information #2:
Using a mass balance equation, infinite dilution equation, and the boron dilution effects of the RCS, we determined the leak rate from CMT A into the RCS and the impact of that leak rate on the boron concentration of CMT A. This provides reasonable assurance that the boron concentration will meet the proposed TS 3.5.2 limit for the remainder of the operating cycle.
Borations are typically performed on a monthly basis to maintain margin to the minimum TS limit. Prior to entering LCO 3.5.2 Condition B on August 8, 2025, operability was justified given the monthly sample results and a quantitative analysis of the leakage from the RCS into CMT A was not performed.
The following table provides the results of 31-day boron concentration sampling to meet TS Surveillance Requirement (SR) 3.5.2.4 since CMT A leakage was first identified in 2024:
Date Boron Concentration (ppm) 5/31/2024 4020 7/1/2024 3961 8/1/2024 3770 9/1/2024 3660 10/2/2024 3448 11/2/2024 3640 12/3/2024 3654 1/3/2025 3629 2/3/2025 3522 3/6/2025 3813 4/6/2025 3537 5/7/2025 3679 6/7/2025 3510 7/8/2025 3406 8/8/2025 3377 8/9/2025 3479