ML25072A282
| ML25072A282 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 03/13/2025 |
| From: | James Drake NRC/NRR/DORL/LPL4 |
| To: | Couture P, Giddens J, Norris G, Peak M Entergy Operations |
| Drake, J | |
| References | |
| EPID L-2025-LLR-0023 RBS-ISI-020 | |
| Download: ML25072A282 (1) | |
Text
From:
Jason Drake To:
Couture III, Philip; NORRIS, GREGORY P; Giddens, John; Peak, Monica Renee Cc:
Tony Nakanishi; Angie Buford; David Dijamco; John Tsao; Hannah McLatchie; Douglas Dodson; Eric Powell; Curtis Wynar
Subject:
VERBAL AUTHORIZATION: River Bend Station, Unit 1 - Relief Request Reactor Pressure Vessel Stud Inspection RBS-ISI-020 Date:
Thursday, March 13, 2025 4:17:00 PM Attachments:
VERBAL AUTHORIZATION - River Bend Station, Unit 1_RPV Stud Flaw_3-13-2025.docx Importance:
High
Dear Mr. Couture,
By telephone conversation on March 13, 2025, the U.S. Nuclear Regulatory Commission (NRC) staff provided a verbal authorization to Entergy Operations, Inc. (Entergy) (the licensee) for the request for relief (RBS-ISI-020), from the examination requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, IWB-3515.2(c), for River Bend Station, Unit 1. Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relief on the basis that compliance to the specified requirements in the Code are impractical based upon the time required to implement additional contingency actions.
The NRC staff finds that Relief Request RBS-ISI-020 will provide reasonable assurance of the structural and leakage integrity of the RPV closure head at River Bend Station, Unit 1.
Accordingly, the NRC staff finds that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(g)(5)(iii). The NRC staff concludes that granting relief pursuant to 10 CFR 50.55a(g)(6)(i) is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility. Therefore, the NRC grants the use of RBS-ISI-020 at River Bend Station, Unit 1, from Mode 4 of the current RF 23 refueling outage until Mode 5 of the RF 24 refueling outage.
The NRC staffs evaluation and verbal authorization is repeated in the attachment to this e-mail.
The following NRC and licensee personnel participated in the conference call:
NUCLEAR REGULATORY COMMISSION
Tony Nakanishi - Chief, Plant Licensing Branch IV (LPL4)
Angie Buford - Chief, Vessels and Internals Branch (NVIB)
David Dijamco - Materials Engineer, NVIB John Tsao - Senior Materials Engineer, NVIB Jason Drake - Project Manager, LPL4 Hannah McLatchie - Project Manager, LPL4
ENTERGY OPERATIONS, INC.
Phil Couture _ Sr. Manager, Fleet Regulatory Assurance - Licensing John Giddens _ Sr. Manager, Fleet Regulatory Assurance - Compliance Greg Norris _ Sr. Staff Tech Specialist - Fleet Regulatory Assurance / BWR Lead Monica Peak _ Sr. Staff Tech Specialist - Fleet Regulatory Assurance / Inspection Support
Lead / Acting RA Manager - RBS Winter Hall _ Sr. Engineer / Central Programs Engineering Andy Nettles _ Sr. Lead Engineer / Central Programs Engineering Caleb Tillotson _ Sr. Engineer / Central Programs Engineering / Acting Supervisor Patrick Williams _ Manager, Fleet Sys & Cmpnts
Please contact me if you have any questions.
Jason Drake Project Manager Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Phone: (301) 415-8378
OFFICE NRR/DORL/LPL4/PM NRR/DNRL/NVIB NRR/DORL/LPL4/BC NAME JDrake ABuford TNakanishi DATE 3/13/2025 3/13/2025 3/13/2025
VERBAL AUTHORIZATION RELIEF REQUEST RBS-ISI-020 REGARDING EXAMINATION OF REACTOR VESSEL CLOSURE HEAD STUD ENTERGY OPERATIONS, INC.
RIVER BEND STATION, UNIT 1 DOCKET NO. 50-458 Technical Evaluation read by Angie Buford, Chief of the Vessels and Internals Branch, Office of Nuclear Reactor Regulation:
By letter dated March 10, 2025 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML25069A746), Entergy Operation Inc. (the licensee) requested relief from the examination requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, IWB-3515.2(c), for River Bend Station, Unit 1.
Relief Request RBS-ISI-020 would allow the licensee to forgo the surface examination of a reactor pressure vessel (RPV) closure head stud for one cycle of operation from the current RF 23 refueling outage until Mode 5 of the next refueling outage (RF 24).
The licensee detected an indication via volumetric examination in a RPV closure head stud (G-1) during the RF 23 refueling outage in February 2025. In accordance with the ASME Code,Section XI, IWB-3515.2(c), flaws detected by volumetric examination shall be investigated by a surface examination. Due to the location of the suspect flaw indication, removal of the RPV stud G-1 is necessary to perform the mandatory surface examination. The licensee proposed the contingency relief request to permit the stud remain in service without the required surface examination if the affected stud cannot be removed during the RF 23 refueling outage. The licensee plans to remove the affected stud in RF 24 refueling outage to perform the surface examination.
Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relief on the basis that compliance to the specified requirements in the Code are impractical based upon the time required to implement additional contingency actions.
The licensee performed two stress analyses using finite element models. One analysis assumes that the affected stud is detensioned. A second analysis assumes the stud fails in service. As part of its technical basis, the licensee will perform a system leakage test in accordance with ASME Code,Section XI, IWB-5221(a) and (b) before start-up to verify the integrity of the RPV head joint. In addition, the licensee stated that the bleed off-line between the double O-ring seal at the RPV head flange is monitored by an annunciator in the control room to monitor the RPV head flange integrity.
The NRC staff evaluated the licensees stress analyses and determined that in both stud scenarios, the stresses of the studs and closure head are within the ASME Code allowable stresses. Additionally, the NRC staff determined that the increase in fatigue usage is insignificant. The licensees evaluation also showed that the increase in flange interface
separation is less than the allowable separation. Thus, the licensees evaluation demonstrates that the structural and leakage integrity of the RPV closure head will be maintained until the next refueling outage (RF 24).
The NRC staff determined that the licensee has provided reasonable assurance that the structural and leakage integrity of the RPV closure head will be maintained until Mode 5 of the RF24 refueling outage because (1) the licensees stress analyses demonstrate the structural integrity of the RPV closure head and RPV closure studs, (2) the licensees system leakage test per IWB-5221(a) and (b), and flange separation evaluation will demonstrate the leakage integrity, and (3) the bleed-off line between the O-rings allows for continued monitoring of the leakage integrity of the RPV closure head.
Authorization read by Tony Nakanishi, Chief of the Plant Licensing Branch IV, Office of Nuclear Reactor Regulation:
As Chief of the Plant Licensing Branch IV, Office of Nuclear Reactor Regulation, I concur with the Vessels and Internals Branchs determinations.
The NRC staff finds that Relief Request RBS-ISI-020 will provide reasonable assurance of the structural and leakage integrity of the RPV closure head at River Bend Station, Unit 1.
Accordingly, the NRC staff finds that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(g)(5)(iii). The NRC staff concludes that granting relief pursuant to 10 CFR 50.55a(g)(6)(i) is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility. Therefore, on March 13, 2025, the NRC grants the use of RBS-ISI-020 at River Bend Station, Unit 1, from Mode 4 of the current RF 23 refueling outage until Mode 5 of the RF 24 refueling outage.