ML25189A070
| ML25189A070 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 07/11/2025 |
| From: | David Wrona Plant Licensing Branch II |
| To: | Erb D Tennessee Valley Authority |
| Green K | |
| References | |
| EPID L-2024-LLR-0081, WBN-2-ISI-02 | |
| Download: ML25189A070 (1) | |
Text
July 11, 2025 WATTS BAR NUCLEAR PLANT, UNIT 2 - AUTHORIZATION AND SAFETY EVALUATION FOR ALTERNATIVE REQUEST NO. WBN-2-ISI-02 (EPID L-2024-LLR-0081)
LICENSEE INFORMATION Recipients Name and Address:
Mr. Delson C. Erb Vice President, OPS Support Tennessee Valley Authority 1101 Market Street, LP 4A-C Chattanooga, TN 37402-2801 Licensee:
Tennessee Valley Authority (TVA)
Plant Name and Unit:
Watts Bar Nuclear Plant (WBN), Unit 2 Docket No.:
50-391 APPLICATION INFORMATION Submittal Date: December 12, 2024 Submittal Agencywide Documents Access and Management System (ADAMS)
Accession No.: ML24347A035 Applicable Containment Inservice Inspection (CISI) Interval and Interval Start/End Dates:
The first 10-year containment inservice inspection (CISI) interval began on October 19, 2016, and is scheduled to end on October 18, 2026. TVA proposes to extend the first CISI interval end date to September 8, 2028.
Alternative Provision: The applicant requested an alternative under Title 10 of the Code of Federal Regulations (10 CFR), paragraph 50.55a(z)(1), Acceptable level of quality and safety.
Applicable Code Edition: American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code,Section XI, 2013 Edition.
Applicable Code of Federal Regulations and ISI Requirements:
10 CFR 50.55a(g)(4)(ii) states, in part, that:
Applicable ISI Code: Successive code of record intervals. Inservice examination of components and system pressure tests conducted during successive code of record intervals must comply with the requirements of the latest edition and addenda of the ASME BPV Code incorporated by reference in paragraph (a) of this section no more than 18 months before the start of the code of record interval (or the optional ASME Code Cases listed in NRC Regulatory Guide 1.147 [Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1], when using ASME BPV Code,Section XI, or NRC Regulatory Guide 1.192 [Operation and Maintenance Code Case Acceptability, ASME OM Code], when using the ASME Operation and Maintenance Code, as incorporated by reference in paragraphs (a)(3)(ii) and (iii) of this section), subject to the conditions listed in paragraph (b) of this section.
ASME BPV Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components:
o Subsection IWA-2430(b) requires that The inspection interval shall be determined by calendar years following placement of the plant into commercial service.
o Subsection IWA-2430(c)(1) requires, in part, that Each inspection interval may be extended by as much as 1 year and may be reduced without restriction, provided the examinations required for the interval have been completed.
Successive intervals shall not extend more than 1 year beyond the original pattern of 10-year intervals and shall not exceed 11 years in length.
o Subsection IWA-2430(c)(3) requires that That portion of an inspection interval described as an inspection period may be extended by as much as 1 year and may be reduced without restriction, provided the examinations required for that period have been completed. This adjustment shall not alter the requirements for scheduling inspection intervals.
o Subsection IWA-2431(a) requires that 1st Inspection Interval 10 years following initial start of plant commercial service.
o Subsection IWE-2411(a) requires that Examinations specified in Tables IWE-2500-1 (E-A), IWE-2500-1 (E-C), and IWE-2500-1 (E-G) shall be completed during each successive inspection interval, in accordance with Table IWE-2411-
- 1.
o Table IWE-2411-1 establishes an inspection interval to consist of three periods that shall conclude at the end of years 3, 7, and 10 within the inspection interval.
Brief Description of the Proposed Alternative: The licensees proposed alternative is to extend, while still using the 2013 Edition of the ASME BPV Code, the first CISI interval for WBN Unit 2 by approximately 23 months to align with the end of the third CISI interval for WBN, Unit 1, Sequoyah Nuclear Plant, Units 1 and 2, and Browns Ferry Nuclear Plant, Units 1, 2, and 3, which are scheduled to end September 8, 2028. Extending the first CISI interval for WBN, Unit 2, by about 23 months, from October 19, 2026, to September 8, 2028, essentially adds a fourth period to the interval. During the extension period, the licensee proposes to perform the periodically required examinations for examination category E-A, Items E1.11, E1.31, and E1.32; examination category E-G, Item E8.10, and examination category E-C, Items E4.11 and E4.12 at WBN, Unit 2.
NRC STAFF EVALUATION The licensee requested an alternative from the requirements of 10 CFR 50.55a(g)(4)(ii) to utilize the 2013 Edition of ASME Section XI Code through the extension period for the WBN, Unit 2, CISI program. To determine whether the proposed examination alternative provides an acceptable level of quality and safety during the extension period, the NRC staff reviewed how it affects the containment inspection requirements in ASME BPV Code,Section XI, Subsection IWE. The NRC staffs review focused on whether the proposed examinations meet the required inspection coverage and frequency in ASME BPV Code, Tables IWE-2500-1(E-A), IWE-2500-1 (E-C), IWE-2500-1 (E-G), and IWE-2411-1, and whether continued use of the 2013 Edition of the ASME BPV Code during the extension period is acceptable. The staffs evaluation of the proposed examinations is as follows.
Examination Category E-A, Item E1.11 (Accessible surface areas of containment vessel pressure retaining boundary): The licensee proposes to perform general visual examinations of 100 percent of the accessible surface areas during one of the two refueling outages (Cycle 7 and Cycle 8) for WBN, Unit 2. The NRC staff finds the proposed examinations during the extension period acceptable because they are consistent with the ASME BPV Code, Table IWE-2500-1 (E-A) requirement to perform general visual examinations of 100 percent of accessible surface areas during each inspection period.
Examination Category E-A, Item E1.31 (Moisture barriers including caulking, flashing, and sealants): The licensee proposes to perform general visual examinations of 100 percent of the moisture barrier seals during one of the two refueling outages (Cycle 7 and Cycle 8) for WBN, Unit 2. The NRC staff finds the proposed examinations during the extension period acceptable because they are consistent with the ASME BPV Code, Table IWE-2500-1 (E-A) requirement to perform general visual examinations of 100 percent of accessible caulking, flashing, and sealants for moisture barriers during each inspection period.
Examination Category E-A, Item E1.32 (Accessible leak chase channel system closures), in accordance with the 2017 Edition of ASME BPV Code,Section XI as required by 10 CFR 50.55a(b)(2)(ix)(K): The licensee proposes to perform general visual examinations on an additional 33 percent of the leak chase channel enclosures during one of the two refueling outages (Cycle 7 and Cycle 8) for WBN, Unit 2. The NRC staff finds the proposed examinations during the extension period acceptable because Table IWE-2500-1 (E-A) of the ASME BPV Code,Section XI, 2017 Edition requires general visual examinations be performed on 100 percent of the accessible leak chase channel system closures during each inspection interval. Since each inspection interval consists of three inspection periods per Table IWE-2411-1, the NRC staff considers the examinations of an additional 33 percent of the leak chase channel enclosures during the extension period reasonable to ensure the full coverage is achieved within the extended interval.
Examination Category E-G, Item E8.10 (Bolted connections): As modified by the response to request for additional information (RAI) (ML25147A130), the licensee proposes to perform a visual test (VT)-1 examination once again on any bolted connection that is disassembled during the extension period (Cycle 7 and Cycle 8). The licensee also proposes to perform a VT-1 examination on any bolted connections not disassembled during the extension period in the in-place condition under tension during the extension period (Cycle 8). In addition, the licensees response to the RAI confirms that VT-1 examinations have been performed on 100 percent of the bolted connections during the current CISI interval and no non-conforming conditions have been identified.
The NRC staff finds the proposed examinations during the extension period acceptable because performing VT-1 examinations during the extension period on 100 percent of the bolted connections meets the requirements of ASME BPV Code, Table IWE-2500-1 (E-G).
Examination Category E-C, Items E4.11 and E4.12 (containment surfaces requiring augmented examination): The licensee stated that there are currently no Category E-C components for WBN, Unit 2, that would require augmented examinations because all CISI examinations that have been performed in the five completed refueling outages have been satisfactory. The licensee proposes to perform examinations on those items that are added to Category E-C as required by IWE-1241 during one of the refueling outages (Cycle 7 and Cycle 8) for WBN, Unit 2. The NRC staff finds the proposed examinations during the extension period acceptable because performing augmented examinations during the extension period on the items added to Category E-C is consistent with the ASME BPV Code, Table IWE-2500-1 (E-C) requirements.
The NRC staff evaluated the continued use of the 2013 Edition of the ASME BPV Code during the extension period rather than using the latest endorsed edition as required by 10 CFR 50.55a(g)(4)(ii). The NRC staff finds that the continued use of the 2013 Edition of the ASME BPV Code, incorporating the implementation approach for Examination Category E-A, Item E1.32 as discussed above, will not result in a reduction in inspection quality; rather, it will improve administrative efficiency, minimize the potential for applying incorrect procedures, and support consistent, fleet-wide implementation of the CISI program by maintaining a common Code of Record for both WBN, Units 1 and 2.
Summary Based on the above evaluation, the NRC staff determines that the licensee has demonstrated that the proposed examinations during the extension period meet the applicable requirements of ASME BPV Code,Section XI. Therefore, the NRC staff finds that that the proposed examination alternative provides an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1).
The NRC staff authorizes the licensee to extend the first CISI interval for WBN, Unit 2, through September 8, 2028, while continuing to use the 2013 Edition of the ASME BPV Code,Section XI.
CONCLUSION The NRC staff has determined that the proposed alternative in the licensees request referenced above, as modified by the licensees response to the RAI, is acceptable and provides an acceptable level of quality and safety.
The NRC staff concludes that the licensee has adequately addressed the regulatory requirements set forth in 10 CFR 50.55a(z)(1).
The NRC staff authorizes the use of proposed alternative WBN-2-ISI-02 at WBN, Unit 2, during the extension period from October 19, 2026, to September 8, 2028.
All other ASME BPV Code,Section XI, requirements for which an alternative was not specifically requested and authorized remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributors: S. Park, NRR G. Wang, NRR Date: July 11, 2025 David Wrona, Chief Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation cc: Listserv DAVID WRONA Digitally signed by DAVID WRONA Date: 2025.07.11 10:58:42 -04'00'
- via eConcurrence NRR-028 OFFICE NRR/DORL/LPLII-2/PM NRR/DORL/LPLII-2/LA NRR/DEX/ESEB/BC NAME KGreen ABaxter ITseng DATE 7/7/2025 7/8/2025 6/30/2025 OFFICE NRR/DSS/SCPB/BC NRR/DORL/LPLII-2/BC NAME MValentin DWrona DATE 7/1/2025 7/11/2025