ML24274A148
| ML24274A148 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 09/30/2024 |
| From: | Luke Haeg Plant Licensing Branch II |
| To: | Osting S Vistra Operating Co. (VistraOpCo) |
| References | |
| L-2024-LLR-0037 | |
| Download: ML24274A148 (4) | |
Text
From:
Luke Haeg Sent:
Monday, September 30, 2024 10:46 AM To:
Osting, Steven Cc:
Subject:
Davis-Besse - RAI re: Relief Request L-23-214 (EPID L-2024-LLR-0037)
Attachments:
Dear Steven Osting,
By letter dated June 5, 2024 (Agencywide Documents Access and Management System (ADAMS)
Accession No. ML24158A004), Vistra Operating Company LLC (Vistra, the licensee) submitted a request from relief (L-23-214) from certain requirements of the ASME Boiler and Pressure Vessel Code,Section XI, for the Davis-Besse Nuclear Power Station, Unit No. 1 (Davis-Besse). The request applied to the fourth 10-year inservice inspection interval and the submittal provided the basis for the determination that the inservice examination of certain welds were determined to be impractical.
The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing your submittal and has identified areas where additional information is needed to complete its review.
A request for additional information (RAI) is attached. A draft RAI was sent to you to ensure that it was understandable, the regulatory basis for the question was clear, and to determine whether the information was previously docketed.
Based on a discussion with you, a response from Vistra to the attached RAI is requested within 30 days from the date of this email (i.e., by October 30, 2024).
The NRC staff considers timely responses to RAIs help to ensure sufficient time is available for staff review and contribute to the NRCs goal of efficient and effective use of staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-0272 or Lucas.Haeg@nrc.gov. Thank you.
Luke Haeg Project Manager NRR/DORL/LPL II-2 U.S. Nuclear Regulatory Commission 301-415-0272
Hearing Identifier:
NRR_DRMA Email Number:
2611 Mail Envelope Properties (DM8PR09MB640728AD5E3982360785B76B98762)
Subject:
Davis-Besse - RAI re Relief Request L-23-214 (EPID L-2024-LLR-0037)
Sent Date:
9/30/2024 10:46:26 AM Received Date:
9/30/2024 10:46:00 AM From:
Luke Haeg Created By:
Lucas.Haeg@nrc.gov Recipients:
"Jeff Whited" <Jeffrey.Whited@nrc.gov>
Tracking Status: None "Osting, Steven" <Steven.Osting@vistracorp.com>
Tracking Status: None Post Office:
DM8PR09MB6407.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 1692 9/30/2024 10:46:00 AM Final RAI L-23-214.pdf 89824 Options Priority:
Normal Return Notification:
No Reply Requested:
No Sensitivity:
Normal Expiration Date:
REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUEST L-23-214 FOR THE FOURTH 10-YEAR INSERVICE INSPECTION INTERVAL EPID L-2024-LLR-0037 VISTRA OPERATIONS COMPANY LLC DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO. 1 DOCKET NO. 50-346 INTRODUCTION By letter dated June 5, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24158A004), Vistra Operating Company LLC (Vistra, the licensee) submitted a request from relief (L-23-214) from certain requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, for the Davis-Besse Nuclear Power Station, Unit No. 1 (Davis-Besse). The request applied to the fourth 10-year inservice inspection (ISI) interval and the submittal provided the basis for the determination that the inservice examination of certain welds were determined to be impractical.
The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing your submittal and has identified areas where additional information is needed to complete its review. In order for the NRC staff to determine if the relief request may be authorized pursuant to 10 CFR 50.55a(g)(5)(iii), the staff requests the additional information below.
REGULATORY BASIS Adherence to Section XI of the ASME Code is mandated by 10 CFR 50.55a(g)(4), which states, in part, that ASME Code Class 1, 2, and 3 components will meet the requirements, except the design and access provisions and the pre-service examination requirements, set forth in the ASME Code,Section XI.
Further, ISI of ASME Code Class 1, 2, and 3 components is to be performed in accordance with Section XI of the ASME Code and applicable edition and addenda as required by 10 CFR 50.55a(g), except where specific relief has been granted by the U.S. Nuclear Regulatory Commission (NRC, the Commission) pursuant to 10 CFR 50.55a(g)(6)(i). Finally, 10 CFR 50.55a(g)(5)(iii) states, in part, that licensees may determine that conformance with certain code requirements is impractical, and that the licensee shall notify the Commission and submit information in support of the determination.
INFORMATION REQUESTED
RAI-1
Issue On document page 8 of the subject request L-23-214, the licensee stated that no recordable indications were detected during the ultrasonic (UT) examination of Weld RC-RPV-WR-34 (Lower Shell-to-Bottom Circumferential Weld) with 50.2% coverage achieved during the scan.
By letter dated February 27, 2013 (ML13059A315), FirstEnergy Nuclear Operating Company (then licensee of Davis-Besse) submitted relief request L-13-076. This request included a notification of impracticality, RR-A36, to obtain the required examination coverage of essentially 100 percent for Weld RC-RPV-WR-34 due to the position of core guide lugs. On document pages 52 and 53 of ML13059A315, a recordable indication within the weld was reported. This indication was determined to be acceptable after the licensee performed an analysis of the size and location of the indication. In the comments for this indication, the previous licensee stated that the indication was recorded during the examination prior to the 2013 submittal.
Request (a) Clarify if the same weld location this indication was detected in the previous two ISI UT examinations was examined as part of the subject request L-23-214.
(b) If this weld location could not be examined in the current ISI interval due to impracticality concerns, provide discussion of any dispositioning for possible growth above acceptance criteria between the previous examination and the end of the fourth ISI interval.
RAI-2
Issue Within the subject request L-23-214, there is a lack of clarity in the information intended to be conveyed by the figures given in support of examinations of Welds RC-RPV-WR-34 and RC-RPV-WR-35.
Figures for RC-RPV-WR-34 will be used as illustrative examples. Figures 1.1-2 and 1.1-3 are described to show Area of Interest and Area of Coverage - Theta Scan (Cross Section) respectively. It is unclear what differences exist in the shaded portion of the figures and what information is being communicated. Figure 1.1-4 appears to be a replication of Figure 1.1-2.
Figures 1.1-3 and 1.1-4 give the impression that 100% of the weld volume was able to be accessed, especially in the absence of further explanatory figures as in the case of Weld RC-RPV-WR-35.
Request Please provide updated figures, including necessary information for interpretation of these images such as a legend and more detailed descriptions, in support of weld inspection coverage calculations for RC-RPV-WR-34 and -35.