CNL-25-077, Request for Additional Information - TVA Alternative Request to Extend Watts Bar, Unit 2, Containment Inservice Inspection Interval
| ML25147A130 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 05/27/2025 |
| From: | Hulvey K Tennessee Valley Authority |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| CNL-25-077, EPID L-2024-LLR-0081 | |
| Download: ML25147A130 (1) | |
Text
1101 Market Street, Chattanooga, Tennessee 37402 CNL-25-077 May 27, 2025 10 CFR 50.55a ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 Facility Operating License No. NPF-96 NRC Docket No. 50-391
Subject:
Request for Additional Information - TVA Alternative Request to Extend Watts Bar, Unit 2, Containment Inservice Inspection Interval (EPID L-2024-LLR-0081)
References:
- 1. TVA letter to NRC, CNL-24-072, Watts Bar Nuclear Plant, Unit 2 - Request for Alternative to Extend First Containment Inservice Inspection Interval, dated December 12, 2024 (ML24347A035)
- 2. NRC electronic mail to TVA, Request for Additional Information - TVA Alternative Request to Extend Watts Bar, Unit 2, Containment Inservice Inspection Interval (EPID L-2024-LLR-0081), dated April 29, 2025 (ML25119A129)
- 3. NRC electronic mail to TVA, CORRECTION: Request for Additional Information - TVA Alternative Request to Extend Watts Bar, Unit 2, Containment Inservice Inspection Interval (EPID L-2024-LLR-0081), dated April 30, 2025 (ML25120A364)
In Reference 1, Tennessee Valley Authority (TVA) submitted a request for alternative from the requirements of paragraph 50.55a(g)(4)(ii) of Title 10 of the Code of Federal Regulations (10 CFR) for Watts Bar Nuclear Plant (WBN), Unit 2, to align the Containment Inservice Inspection Program interval end date with the TVA fleet interval end dates.
In References 2 and 3, the Nuclear Regulatory Commission (NRC) issued a request for additional information (RAI) with a TVA response due by May 29, 2025. The enclosure to this letter provides the response to the RAIs.
U.S. Nuclear Regulatory Commission CNL-25-077 Page 2 May 27, 2025 There are no new regulatory commitments contained in this letter. Please address any questions regarding this request to Amber V. Aboulfaida, Senior Manager, Fleet Licensing, at avaboulfaida@tva.gov.
Respectfully, Kimberly D. Hulvey General Manager, Nuclear Regulatory Affairs & Emergency Preparedness
Enclosure:
Response to Nuclear Regulatory Commission Request for Additional Information cc:
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant NRC Project Manager - Watts Bar Nuclear Plant Digitally signed by Edmondson, Carla Date: 2025.05.27 11:01:45 -04'00'
Enclosure CNL-25-077 E-1 of 2 Response to Nuclear Regulatory Commission Request for Additional Information
==
Introduction:==
By letter dated December 12, 2024 (Agencywide Documents Access and Management System Accession No. ML24347A035), Tennessee Valley Authority (TVA or the licensee) requested an alternative from the requirements of paragraph 50.55a(g)(4)(ii) of Title 10 of the Code of Federal Regulations (10 CFR) for Watts Bar Nuclear Plant (WBN), Unit 2, to align the Containment Inservice Inspection Program interval end date with the TVA fleet interval end dates.
Background:
The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, Table IWE-2500-1 (E-G), Examination Category E-G, Pressure Retaining Bolting, 2013 Edition, requires 100 percent of each Item E8.10, Bolted Connections to be examined during the first and successive inspection intervals. Note (2) states that [e]xamination may be performed with the connection assembled and bolting in place under tension, provided the connection is not disassembled during the interval. If the bolted connection is disassembled for any reason during the interval, the examination shall be performed with the connection disassembled.
Section VI, Proposed Alternative and Basis for Use in the Enclosure of Proposed Alternative WBN-2-ISI-02 states, There are two refueling outages (Cycle 7 and Cycle 8) for WBN Unit 2 that are scheduled to occur between October 18, 2026, and September 8, 2028. This change adds a fourth period (extension period) with these dates to ensure that the structural integrity of the steel containment vessel is monitored and maintained. For Examination Category E-G, Item E8.10,Section VI of Proposed Alternative WBN-2-ISI-02 states that [f]or bolted connections, 100 percent of the examination requirements will be completed by the end of the originally scheduled interval for Unit 2. However, any bolted connections that are disassembled during this timeframe, and were not previously examined in the disassembled condition, will be VT-1 examined in the disassembled condition during the extension period.
Regulatory Basis:
Section 50.55a(g)(4)(ii) of 10 CFR requires inservice examination of components and system pressure tests conducted during successive 120-month inspection intervals to comply with the requirements of the latest edition and addenda of the ASME Code incorporated by reference in paragraph (a) of 10 CFR 50.55a 18 months before the start of the 120-month inspection interval.
Paragraph 50.55a(z)(1) of 10 CFR requires the applicant to demonstrate that, when alternatives to the requirements of paragraphs (b) through (h) of 10 CFR 50.55a or portions thereof are used, the proposed alternative would provide an acceptable level of quality and safety.
Issue:
Proposed Alternative WBN-2-ISI-02 lacks information regarding how the proposed examinations of bolted connections at WBN, Unit 2, during the extension period will provide an acceptable level of quality and safety.
Enclosure CNL-25-077 E-2 of 2 Request:
- 1. Summarize the examination results, conclusions, and disposition of non-conformances for bolted connections at WBN, Unit 2, that have been completed during the initial interval.
- 2. Provide the justification for why the proposed examinations on bolted connections at WBN, Unit 2, during the proposed extension period will demonstrate an acceptable level of quality and safety.
TVA Response to RAI 1 One hundred percent of the bolted connections in the WBN Unit 2 Containment Inservice Inspection (CISI) Program have been successfully VT-1 examined for the current interval. All examinations were satisfactory and there were no non-conforming conditions identified.
TVA Response to RAI 2 In lieu of the originally proposed examinations for the Examination Category E-G, Item E8.10, TVA will perform the following:
During the extension period (Cycle 7 and Cycle 8), any bolted connection that is disassembled will be VT-1 examined once again. Any bolted connections not disassembled during this extension period will be VT-1 examined in the in-place condition under tension during Cycle 8. This is an acceptable level of quality and safety, as this will ensure 100 percent of the bolted connections within the scope of the WBN Unit 2 CISI program are examined during the extension period.