ML24271A005
| ML24271A005 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 09/26/2024 |
| From: | John Lamb Plant Licensing Branch II |
| To: | Pournaras D, Sparkman W Southern Nuclear Operating Co |
| References | |
| L-2024-LLR-0041 | |
| Download: ML24271A005 (4) | |
Text
From:
John Lamb Sent:
Thursday, September 26, 2024 1:08 PM To:
Pournaras, DeLisa S.; Sparkman, Wesley A.
Cc:
Joyce, Ryan M.
Subject:
For Your Response - RAI - Farley and Vogtle 1 and 2 - Proposed Alternative Request for SG Welds (L-2024-LLR-0041)
DeLisa and Wes, By letter dated June 18, 2024, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24170B057), Southern Nuclear Operating Company (SNC, the licensee) submitted a proposed alternative, Alternative GEN-ISI-ALT-2024-002, to the inservice inspection (ISI) requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)Section XI regarding the steam generator (SG) welds at Joseph M. Farley Nuclear Plant (Farley), Units 1 and 2 and Vogtle Electric Generating Plant (Vogtle), Units 1 and 2.
Specifically, pursuant to Title 10 of the Code of Federal Regulations, Part 50, Section 55a, Paragraph (z)(1) (10 CFR 50.55a(z)(1)), SNC is proposing to perform the required volumetric examinations of the subject SG welds every other ISI interval, rather than the ASME Code Section XI requirement of every ISI interval.
The U.S. Nuclear Regulatory Commission (NRC) staff has determined that additional information is required for the staff to complete its review. On September 10, 2024, the NRC staff sent the draft RAIs to review to determine if a clarifying call was needed. SNC requested a clarifying call on September 12, 2024. The clarifying call was held on September 26, 2024. SNC stated that it would respond to this RAI within 30 days from the date of this email.
If you have any questions, contact me.
John G. Lamb Senior Project Manager NRC/NRR/DORL/LPLII-1 (301) 415-3100 REQUEST FOR ADDITIONAL INFORMATION (RAI)
By letter dated June 18, 2024 (Agencywide Document Access and Management System Accession Number ML24170B057), Southern Nuclear Operating Company (the licensee) submitted to the United States Nuclear Regulatory Commission (NRC) a proposed alternative, Alternative GEN-ISI-ALT-2024-002, to the inservice inspection (ISI) requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)
Section XI regarding the steam generator (SG) welds at Joseph M. Farley Nuclear Plant, Units 1 and 2 and Vogtle Electric Generating Plant, Units 1 and 2.
Specifically, pursuant to Title 10 of the Code of Federal Regulations, Part 50, Section 55a, Paragraph (z)(1) (10 CFR 50.55a(z)(1)), the licensee is proposing to perform the required volumetric examinations of the subject SG welds every other ISI interval, rather than the ASME Code Section XI requirement of every ISI interval. The licensee referred to the results of the
probabilistic fracture mechanics (PFM) analyses in the following Electric Power Research Institute (EPRI) non-proprietary report as the primary basis for proposed alternative:
EPRI Technical Report 3002015906, Technical Bases for Inspection Requirements for PWR Steam Generator Class 1 Nozzle-to-Vessel Welds and Class 1 and Class 2 Vessel Head, Shell, Tubesheet-to-Head and Tubesheet-to-Shell Welds, 2019 (hereinafter referred to as EPRI report 15906, ADAMS Accession No. ML20225A141).
The U.S. Nuclear Regulatory Commission (NRC) staff has determined that additional information is required for the staff to complete its review.
Regulatory Basis The NRC has established requirements in 10 CFR Part 50 to protect the structural integrity of structures and components in nuclear power plants. Among these requirements are the ISI requirements of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a to ensure that adequate structural integrity of SG vessels (including their welds) is maintained through the service life of the vessels. Therefore, the regulatory basis for the following request for additional information (RAI) is related to demonstrating that the proposed alternative ISI requirements would ensure adequate structural integrity of the licensees SG welds, and thereby would provide an acceptable level of quality and safety per 10 CFR 50.55a(z)(1).
Issue SNC cited several precedents to support NRC approval of the proposed alternative, including references 9.15 through 9.18 of the licensee's submittal, dated June 18, 2024. However, the NRC staff noted some differences between the current submittal and the cited precedents.
Some of the cited precedents were approved for one plant, while the current submittal applies to more than one plant site. Some of the cited precedents were related to ISI interval extensions, whereas the current submittal proposes to perform the examinations every other ISI interval. It appears that the safety evaluation (SE) dated September 25, 2023 (ML23256A088) may be a more appropriate precedent, as it more closely resembles these aspects of SNCs request. On page E-13 of SNCs submittal, dated June 18, 2024, SNC states that scope expansion will be performed in accordance with the ASME Section XI code of record. This approach to scope expansion appears to be not consistent with that approved by the NRC staff in the SE dated September 25, 2023. The supplemental letter dated July 20, 2023 (ML23201A140) from that licensee provides further information on an approach to scope expansion that the NRC staff found to be acceptable.
RAI-1
(a) If indications are detected that exceed the acceptance standards of ASME Code,Section XI, IWB-3500, confirm that it will be evaluated as required by ASME Code,Section XI (which includes requirements for successive inspections and additional examinations). Describe other actions (if any) specified in the plants corrective action program to ensure that the integrity of the component is adequately maintained.
(b) If indications are detected that exceed the acceptance standards of ASME Code,Section XI, IWB-3500, then scope expansion may be appropriate to assess extent of
condition. Furthermore, if industry-wide operating experience indicates that a new or novel degradation mechanism is possible in SG welds, scope expansion may be appropriate to ensure that no such mechanism is occurring in the subject plants. Discuss the detailed scope expansion plans for these scenarios.
Hearing Identifier:
NRR_DRMA Email Number:
2610 Mail Envelope Properties (MN2PR09MB508417ACD051E5E371F25E7BFA6A2)
Subject:
For Your Response - RAI - Farley and Vogtle 1 and 2 - Proposed Alternative Request for SG Welds (L-2024-LLR-0041)
Sent Date:
9/26/2024 1:07:43 PM Received Date:
9/26/2024 1:07:00 PM From:
John Lamb Created By:
John.Lamb@nrc.gov Recipients:
"Joyce, Ryan M." <RMJOYCE@southernco.com>
Tracking Status: None "Pournaras, DeLisa S." <DSPOURNA@SOUTHERNCO.COM>
Tracking Status: None "Sparkman, Wesley A." <WASPARKM@southernco.com>
Tracking Status: None Post Office:
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