ML24087A010
| ML24087A010 | |
| Person / Time | |
|---|---|
| Site: | North Anna  (NPF-4) |
| Issue date: | 03/26/2024 |
| From: | Ed Miller NRC/NRR/DORL/LPL2-1 |
| To: | Sly C Dominion Energy Virginia |
| References | |
| Download: ML24087A010 (3) | |
Text
From:
Ed Miller Sent:
Tuesday, March 26, 2024 11:35 AM To:
craig.d.sly@dominionenergy.com Cc:
Shayan.Sinha@dominionenergy.com; julie.h.hough@dominionenergy.com
Subject:
Verbal Relief for North Anna Unit 1 Mr. Sly, This email serves as documentation of the verbal relief that NRC provided this morning (March 26, 2024). This email will be made publicly available. As discussed on the call, a formal Safety Evaluation (SE) will be issued at a later date in accordance with NRR Office Instruction LIC-102. The verbal authorization does not preclude the NRC staff from asking additional clarification questions while preparing the written SE.
Ed Miller (301) 415-2481 Technical Evaluation read by Angie Buford, Chief of the Vessels and Internals Branch, Office of Nuclear Reactor Regulation:
By letter dated March 22, 2024 (Agencywide Documents and Access Management System (ADAMS)
Accession No. ML24082A274), as supplemented by letter dated March 25, 2024 (ML24086A089),
Virginia Electric and Power Company (Dominion Energy Virginia, the licensee) requested relief from the examination requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, Subsection IWB-2430, for North Anna Power Station Unit 1. The proposed alternative would allow the inspection schedule of additional reactor coolant pumps from the Spring 2024 refueling outage to the Fall 2025 refueling outage. Pursuant to Title 10 of the Code of Federal Regulations (CFR) Part 50, Section 10 CFR 50.55a(z)(2), the licensee submitted for Nuclear Regulatory Commission (NRC) review and approval Alternative Request N1-I5-NDE-007 on the basis of hardship.
North Anna Unit 1 has three reactor coolant pump (RCP), 1-RC-P-1A (1A), 1-RC-P-1B (1B) and 1-RC-P-1C (1C). During the Spring 2024 refueling outage, the licensee refurbished RCP 1A as part of its subsequent license renewal project. During replacement, the licensee identified impressions/dents on the inside surface of the pump casing that were caused by the broken cap screws on the diffuser adapter that fell to the bottom of the 1A RCP casing. The licensee accepted the flaw in 1A RCP casing for continued service per the ASME Code,Section XI, IWB-3142.4. The ASME Code,Section XI, IWB-2430(a)(1)(a) requires the licensee to examine one additional RCP during the same Spring 2024 refueling outage.
Because of the hardship, the licensee proposed to examine additional RCP(s) in the Fall 2025 refueling outage.
The NRC staff evaluated the justification for delaying the examination of additional RCP to the 2025 refueling outage by assessing the licensees evaluation of structural integrity of degraded 1A RCP casing with respect to 1B or 1C pump casing.
Based on the information submitted, the NRC staff determined that (1) the structural integrity of 1A RCP casing will be maintained for the remaining life of the plant license based on fracture mechanics analysis and stress analysis, (2) the structural integrity of 1B RCP and 1C RCP will be maintained based on the assessment of the structural integrity of 1A RCP, (3) the defense-in-depth measures will trip the
reactor or RCPs if any one of the RCPs cannot achieve its function, (4) the hardship that would be incurred if additional examination is performed during the Spring 2024 refueling outage is reasonable, and (5) the risk of the degraded 1A RCP casing to the safe operation and public health and safety is low.
The NRC staff concludes that the licensee has provided reasonable assurance that the structural integrity of the three RCPs will be maintained for the remainder of the plant license.
Authorization read by Michael Markley, Chief of the Plant Licensing Branch II-1, Office of Nuclear Reactor Regulation:
As Chief of the Plant Licensing Branch II-1, Office of Nuclear Reactor Regulation, I concur with the Vessels and Internals Branchs determinations.
The NRC staff finds that the proposed alternative in Alternative Request N1-I5-NDE-007 will provide reasonable assurance of the structural integrity of the 1A, 1B, and 1C RCP casings. The NRC staff determines that complying with the specified ASME Code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, on March 26, 2024, the NRC authorizes the use of Alternative Request N1-I5-NDE-007 at North Anna Power Station, Unit 1, through restart from the fall 2025 refueling outage, before the start of Cycle 32.
Hearing Identifier:
NRR_DRMA Email Number:
2440 Mail Envelope Properties (SA1PR09MB748716294ECE778101B7E481E9352)
Subject:
Verbal Relief for North Anna Unit 1 Sent Date:
3/26/2024 11:34:39 AM Received Date:
3/26/2024 11:34:00 AM From:
Ed Miller Created By:
Ed.Miller@nrc.gov Recipients:
"Shayan.Sinha@dominionenergy.com" <Shayan.Sinha@dominionenergy.com>
Tracking Status: None "julie.h.hough@dominionenergy.com" <julie.h.hough@dominionenergy.com>
Tracking Status: None "craig.d.sly@dominionenergy.com" <craig.d.sly@dominionenergy.com>
Tracking Status: None Post Office:
SA1PR09MB7487.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 4549 3/26/2024 11:34:00 AM Options Priority:
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