ML25267A090

Unit 1 - Request for Approval of Revision to Surveillance Capsule Withdrawal Schedule

ML25267A090
Person / Time
Site:	North Anna
Issue date:	09/23/2025
From:	James Holloway Dominion, Dominion Energy, Dominion Energy Virginia
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
25-243
Download: ML25267A090 (1)

Text

Dominion Energy Virginia, Inc.

5000 Dominion Boulevard, Glen Allen, VA 23060 DominionEnergy.com United States Nuclear Regulatory Commission Serial No.:

25-243 Attention: Document Control Desk NRA/JHH:

R0 Washington, DC 20555-0001 Docket No.

50-338 License No.:

NPF-4 VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT 1 REQUEST FOR APPROVAL OF REVISION TO SURVEILLANCE CAPSULE WITHDRAWAL SCHEDULE Pursuant to 10 CFR 50, Appendix H, Section III.B.3, Virginia Electric and Power Company (Dominion Energy Virginia or Dominion) hereby requests approval for a revision to the North Anna Power Station (NAPS) Unit 1 reactor vessel material surveillance program withdrawal schedule.

In Reference 1, as supplemented by Reference 2, Dominion submitted a requested change to the surveillance capsule withdrawal schedules for NAPS Units 1 and 2. In Reference 3, the NRC approved the current NAPS Units 1 and 2 surveillance capsule withdrawal schedules, contained in the NAPS Updated Final Safety Analysis Report (UFSAR) Tables 5.4-2 and 5.4-3. This schedule requires withdrawal of Capsule X at a cumulative core burnup of approximately 39.1 Effective Full Power Years (EFPY). The Capsule X withdrawal was planned for the currently ongoing NAPS Unit 1 Thirty-First Refueling Outage (NAPS 1R31), accordingly.

Despite repeated attempts, with additional extraction force applied in each subsequent attempt, refueling and vendor personnel have not been able to withdraw Capsule X with the Irradiated Sample Handling Tool (ISHT). It was determined that applying additional extraction force to the ISHT would likely lead to damage of the tool and the potential to introduce foreign material into the reactor vessel.

Therefore, Dominion requests approval of a revision to the surveillance capsule schedule to reflect withdrawal of Capsule X during the NAPS Unit 1 Thirty-Third Refueling Outage 1R33, which is currently scheduled for Fall 2028. Delaying Capsule X withdrawal until the NAPS 1R33 outage will allow the withdrawal to be planned concurrent with a core barrel lift, which will allow for improved access and alternate methods of capsule removal if attempts to remove the capsule with the ISHT are not successful. provides a description and assessment of the proposed change to the reactor vessel material surveillance program withdrawal schedule. Attachment 2 provides

Serial No.25-243 Docket No. 50-338 Page 2 of 3 a mark-up of the affected NAPS UFSAR page. The Attachment 2 mark-up also contains two changes unrelated to this submittal; an error correction and an administrative change to update a reference. The error correction has been documented in Dominions Corrective Action Program.

To support implementation of the revised withdrawal schedule, Dominion requests approval of this proposed change by October 3, 2025. As documented in Attachment 1, the proposed delayed removal of Capsule X maintains compliance with Dominions current reactor vessel materials surveillance program requirements. Dominion will revise NAPS UFSAR Table 5.4-2 to incorporate the change following NRC approval.

Should you have any questions regarding this submittal, please contact Julie Hough at (804) 273-3586.

Sincerely, James E. Holloway Vice President Nuclear Engineering & Fleet Support References:

1. Letter from Dominion Energy Virginia to NRC, Revised Reactor Vessel Material Capsule Withdrawal Schedules, dated November 25, 2019 (ADAMS Accession No. ML19329C748)

2. Letter from Dominion Energy Virginia to NRC, Revised Reactor Vessel Material Capsule Withdrawal Schedules Response to Request for Additional Information, dated May 19, 2020 (ADAMS Accession No. ML20140A336)

3. Letter from NRC to Dominion Energy Virginia, North Anna Power Station, Unit Nos. 1 and 2 - RE: Request to Revise Reactor Vessel Material Surveillance Capsule Withdrawal Schedules (EPID L-2019-LLL-0038), dated August 6, 2020 (ADAMS Accession No. ML20216A299)

Attachments: 1. Description and Assessment of the Proposed Revision to the North Anna Power Station Unit 1 Surveillance Capsule Withdrawal Schedule

2. Surveillance Capsule Withdrawal Schedule UFSAR Mark-Up

Serial No.25-243 Docket No. 50-338 Page 3 of 3 Commitments made in this letter:

1. Following receipt of NRC approval, the NAPS UFSAR Table 5.4-2 will be updated to include the revised UFSAR table.

cc: U. S. Nuclear Regulatory Commission, Region II Mr. G. E. Miller NRC Senior Project Manager - North Anna Power Station U. S. Nuclear Regulatory Commission NRC Senior Resident Inspector North Anna Power Station

Serial No.25-243 Docket No. 50-338 ATTACHMENT 1 DESCRIPTION AND ASSESSMENT OF THE PROPOSED REVISION TO THE NORTH ANNA POWER STATION UNIT 1 SURVEILLANCE CAPSULE WITHDRAWAL SCHEDULE VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION ENERGY VIRGINIA)

NORTH ANNA POWER STATION UNIT 1

Serial No.25-243 Docket No. 50-338, Page 1 of 3 Proposed Revision to the North Anna Power Station (NAPS) Unit 1 Surveillance Capsule Withdrawal Schedule

===1.

Background===

Appendix H of 10 CFR 50 (Reference 1) requires a material surveillance program to monitor changes in the fracture toughness properties of ferritic material in the reactor vessel beltline region that result from exposure of these materials to neutron irradiation and the thermal environment. Under this program, fracture toughness test data is obtained and analyzed from material specimens exposed in surveillance capsules that are withdrawn periodically from the reactor vessel. Test results must be reported to the NRC within eighteen months of the date of the capsule withdrawal. In addition,Section III.B.3 of Appendix H to 10 CFR 50 requires the NRC to approve the capsule withdrawal schedule prior to implementation.

The design of the surveillance program and the withdrawal schedule must meet the requirements of the edition of ASTM E 185 (Reference 2) that was current at the issuance of the ASME Code to which the reactor vessel was purchased. The NAPS Unit 1 reactor vessel surveillance program was based on ASTM E 185-73 and meets the testing requirements of ASTM E185-82. Dominion has withdrawn and tested three capsules from Unit 1. Testing of Capsule X in 2025 would satisfy the initial license renewal schedule for Unit 1. Based upon the transition temperature shift (the mean value of the adjustment or shift in reference temperature for nil-ductility transition caused by irradiation) of >100°F but <200°F, only four Unit 1 capsules are required for testing per ASTM E185-82.

The schedule to withdraw Capsule X during the NAPS Unit 1 Fall 2025 Refueling Outage (1R31) was requested by Dominion by \

letter dated November 25, 2019 (Reference 3), as supplemented by \

letter dated May 18, 2020 (Reference 4). The NRC approved this schedule revision by letter to Dominion dated August 6, 2020 (Reference 5). Removal of Capsule X was scheduled to occur during 1R31, in the 60-year initial period of extended operation.

2.

Proposed Revision to Program/Withdrawal Schedule The Unit 1 Reactor Material Surveillance Program withdrawal schedule is contained in the NAPS Updated Final Safety Analysis Report (UFSAR). The proposed change revises the schedule to change the removal time for Capsule X from 1R31 in Fall 2025 to 1R33 in Fall 2028.

3.

Justification The cumulative core burnup at the end of NAPS Unit 1 Cycle 31 was 39.3 effective full power years (EFPY). Per NAPS UFSAR Table 5.4-2 (Reference 6), Capsule X was scheduled to be removed at the nearest outage after reaching 39.1 EFPY, which corresponded to fluence on Capsule X of 7.20x1019 n/cm2. A removal time of 39.3 EFPY

Serial No.25-243 Docket No. 50-338, Page 2 of 3 for Capsule X corresponds to a surveillance capsule fluence of 7.24x1019 n/cm2. A removal time of 41.9 EFPY as projected for NAPS 1R33 (Fall 2028) corresponds to a projected surveillance capsule fluence of 7.69x1019 n/cm2.

The maximum fluence at the pressure vessel clad/base metal interface at 60 years of operation (50.3 EFPY) is projected to be 5.13x1019 n/cm2. The maximum fluence at the pressure vessel clad/base metal interface of 80 years of operation is projected to be 7.2x1019 n/cm2 (Reference 7).

The Capsule X fluence at both 39.3 EFPY and 41.9 EFPY will be greater than one times the 60-year fluence of 5.13x1019 n/cm2 at the pressure vessel clad/base metal interface, but less than two times the 60-year fluence. The Capsule X fluence at both 39.3 EFPY and 41.9 EFPY will also be greater than one times the 80-year fluence of 7.2x1019 n/cm2 at the pressure vessel clad/base metal interface, but less than two times the 80-year fluence. The Capsule X fluence will remain within these limits even with delayed removal until NAPS 1R33 (Fall 2028).

Therefore, the proposed withdrawal schedule revision for NAPS Unit 1 Capsule X will continue to satisfy the NUREG-1801 (Reference 8) and NUREG-2191 (Reference 9) requirements. This request to revise the removal time for NAPS Unit 1 Capsule X maintains compliance with the current reactor pressure vessel materials surveillance program requirements for NAPS Unit 1.

4.

References

1. 10 CFR 50, Appendix H, "Reactor Vessel Material Surveillance Program Requirements."

2. ASTM Standard E185, "Standard Practice for Conducting Surveillance Tests for Light-Water Cooled Nuclear Power Reactor Vessels."

3. Letter from Dominion Energy Virginia to NRC, Revised Reactor Vessel Material Capsule Withdrawal Schedules, dated November 25, 2019 (ADAMS Accession No. ML19329C748).

4. Letter from Dominion Energy Virginia to NRC, Revised Reactor Vessel Material Capsule Withdrawal Schedules Response to Request for Additional Information, dated May 19, 2020 (ADAMS Accession No. ML20140A336).

5. Letter from NRC to Dominion Energy Virginia, North Anna Power Station, Unit Nos.

1 and 2 - RE: Request to Revise Reactor Vessel Material Surveillance Capsule Withdrawal Schedules (EPID L-2019-LLL-0038), dated August 6, 2020 (ADAMS Accession No. ML20216A299).

6. NAPS UFSAR Table 5.4-2, Surveillance Capsule Withdrawal Schedule for North Anna Unit 1, Revision 60.04 dated August 14, 2025

Serial No.25-243 Docket No. 50-338, Page 3 of 3

7. WCAP-18015-NP, Revision 2, Extended Beltline Pressure Vessel Fluence Evaluations Applicable to North Anna 1 & 2, September 2018.

8. NUREG-1801, Generic Aging Lessons Learned (GALL) Report, Revision 0, July 2001.

9. NUREG-2191, Generic Aging Lessons Learned for Subsequent License Renewal (GALL-SLR) Report, Revision 0, July 2017.

Serial No.25-243 Docket No. 50-338 ATTACHMENT 2 SURVEILLANCE CAPSULE WITHDRAWAL SCHEDULE UFSAR MARK-UP VIRGINIA ELECTRIC AND POWER COMPANY DOMINION ENERGY VIRGINIA NORTH ANNA POWER STATION UNIT 1