ML23030B903
| ML23030B903 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 01/30/2023 |
| From: | Klos L Plant Licensing Branch II |
| To: | Treadway R Duke Energy Carolinas |
| Klos L | |
| References | |
| Download: ML23030B903 (1) | |
Text
1 John Klos From:
John Klos Sent:
Monday, January 30, 2023 4:35 PM To:
Sigmon, Chet Austin; Treadway, Ryan I Cc:
Subject:
Formal release of RAIs for McGuire Unit 1, Relief Request Impractical RPV RX coolant system welds, due Mar. 1, 2023
- Chet, By letter dated September 21, 2022 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML22264A110), Duke Energy Carolinas LLC (the licensee) requested relief from the examination coverage requirement of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, 2007 Edition through the 2008 Addenda, at McGuire Nuclear Station Unit
- 1. Pursuant to Title 10, Code of Federal Regulations, Part 50.55a (10 CFR 50.55a(g)(5)(iii)), the licensee submitted Relief Request RA-22-0024 for Nuclear Regulatory Commission (NRC) review and approval on the basis that the required examination coverage is impractical due to physical obstructions and limitations imposed by design, geometry, and materials of construction of the subject components. Duke Energy specifically requests relief from ASME Code paragraphs IWA-2200 and IWB-2500 for volumetric examination of certain Class 1 components on the basis that conformance with these ASME Code requirements is impractical as conformance would require extensive structural modifications to the components or surrounding structures. The relief request includes welds that were inspected during the fourth 10-year interval for which relief from the ASME Code examination coverage requirement is being requested.
To complete its review, the NRC staff requests additional information (RAI) as follows. These RAIs were reviewed with Duke Energy staff on Jan. 30, 2023 and are now released with a 30-day calendar response deadline from today; thereby, they are due by the close of business Wed. March 1, 2023 2.0 REGULATORY BASIS The regulation in 10 CFR 50.55a(g)(5)(iii) states that If the licensee has determined that conformance with a code requirement is impractical for its facility, the licensee shall notify the [Nuclear Regulatory Commission (NRC)] and submit, as specified in Section 50.4, information to support the determinations. Determinations of impracticality in accordance with this section must be based on the demonstrated limitations experienced when attempting to comply with the code requirements during the inservice inspection interval for which the request is being submitted. Requests for relief made in accordance with this section must be submitted to the NRC no later than 12 months after the expiration of the initial or subsequent 120-month inspection interval for which relief is sought.
Pursuant to 50.55a(g)(6)(i), Impractical ISI Requirements: Granting of Relief, the Commission will evaluate determinations under paragraph (g)(5) of 10 CFR 50.55a, that ASME code requirements are impractical. The Commission may grant such relief and may impose such alternative requirements as it determines are authorized by law, will not endanger life or property or the common defense and security, and are 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.
2 3.0 Request for Additional Information
RAI-1
Issue Table 1 of Enclosure 1 of the relief request shows that the examination coverage achieved for the Lower Shell to Bottom Head circumferential weld 1RPV10-442 and the Upper Shell at 180° longitudinal weld 1RPV1-442B were 59.6% and 51.5%, respectively of the required volume. The NRC staff understands that this low examination coverage was caused by the interference of the in-core instrumentation nozzles. The NRC staff recognizes that the licensee has performed required volumetric examinations in accordance with the ASME Code,Section XI. However, the NRC staff is seeking understanding whether the licensee performed additional best effort examinations beyond the ASME Code requirements such as non-qualified visual examination to support its relief request.
Request Discuss whether as part of the ultrasonic testing (UT) examination of welds 1RPV10-442 and 1RPV1-442B, a non-qualified visual inspection was performed as part of best effort to verify that the surface of the welds that was not examined is not degraded, if a visual inspection was achievable.
RAI-2
Issue of the relief request states that flaws/indications have been detected in four welds, 1RPV1-442B, 1RPV3-442A, 1RPV3-442B, and 1RPV3-442C. The NRC staff notes that the indications detected in the subject welds are acceptable in accordance with the acceptance standards of IWB-3000 of the ASME Code,Section XI. As such, the ASME Code,Section XI does not require successive examinations of the subject welds. However, because the licensee did not achieve essentially 100% of the examination coverage, the NRC staff is seeking understanding whether these welds will be inspected in the future, providing further opportunities to monitor the potential growth of the indications in the subject welds.
Request Clarify whether these welds will be inspected in the future ISI intervals.
RAI-3
Issue Section 6.0 of Enclosure 1 states that Based on the volumetric coverage obtained, along with the completed ASME Code required surface examination and System Pressure Tests, it is reasonable to conclude that if significant service induced degradation were occurring, it would have been evident by the examinations and testing that were performed. The statement mentions a surface examination being performed. However, the NRC staff notes that Table IWB 2500-1 of the 2007 Edition through 2008 Addenda of the ASME Code Section XI requires only ultrasonic examination, not surface examination, to be performed for the subject welds of the relief request (i.e., welds under Examination Category B-A with Item numbers B1.11 and B1.12, and Examination Category B-D with Item number B3.110).
Request Clarify whether a surface examination was performed on the subject welds of the relief request. If surface examination(s) was (were) performed, provide the results thereof.
Thanks in advance,
3 John Klos DORL Mcguire, Surry Licensing Project Manager U.S. NRC, Office of Nuclear Reactor Regulation (NRR),
Division of Operating Reactor Licensing (DORL),
NRC/NRR/DORL/LPL2-1, MS O9E3 Washington, DC 20555-0001 301.415.5136, John.Klos@NRC.gov