ML24033A300

Summary of Regulatory Audit Regarding a Proposed Alternative to ASME Code,Section XI Requirements for Containment Building Inspections

ML24033A300
Person / Time
Site:	South Texas
Issue date:	02/07/2024
From:	Dennis Galvin Plant Licensing Branch IV
To:	Gerry Powell South Texas
Galvin D
References
EPID L-2023-LLR-0004
Download: ML24033A300 (1)

Text

February 7, 2024

Mr. G. T. Powell President and Chief Executive Officer STP Nuclear Operating Company P.O. Box 289 Wadsworth, TX 77483

SUBJECT:

SOUTH TEXAS PROJECT, UNITS 1 AND 2 -

SUMMARY

OF REGULATORY AUDIT REGARDING A PROPOSED ALTERNATIVE TO ASME CODE, SECTION XI REQUIREMENTS FOR CONTAINMENT BUILDING INSPECTIONS (EPID L-2023-LLR-0004)

Dear Mr. Powell:

By letter dated February 1, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23032A484), as sup plemented by letters dated March 9, 2023 (ML23068A364), August 17, 2023 (ML23229A499), and December 14, 2023 (ML23348A375),

STP Nuclear Operating Company (STPNOC, the licensee) submitted a proposed alternative to subsection IWL of the American Society of Mechanical Engineer Boiler and Pressure Vessel Code (ASME Code),Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, regarding the frequency of certain containment unbonded post-tensioning system inservice inspections at South Texas Project Units 1 and 2.

To support its review, the U.S. Nuclear Regulatory Commission (NRC) staff conducted a regulatory audit via the use of an online reference portal set up by the licensee, and a webinar.

The NRC staff reviewed documents and held discuss ions with the licensees staff concerning the proposed alternative. The audit summary is enclosed with this letter.

G. Powell

If you have any questions, please contact me at 301-415-6256 or via email at Dennis.Galvin@nrc.gov.

Sincerely,

/RA/

Dennis J. Galvin, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Docket Nos. 50-498 and 50-499

Enclosure:

Audit Summary

cc: Listserv OFFICE OF NUCLEAR REACTOR REGULATION

REGULATORY AUDIT

SUMMARY

IN SUPPORT OF PROPOSED ALTERNATIVE TO ASME CODE, SECTION XI

REQUIREMENTS FOR CONTAINMENT BUILDING INSPECTIONS

STP NUCLEAR OPERATING COMPANY

SOUTH TEXAS PROJECT, UNITS 1 AND 2

DOCKET NOS. 50-498 AND 50-499

1.0 BACKGROUND

By letter dated February 1, 2023 (Agencywide Documents Access and Management (ADAMS)

Accession No. ML23032A484), as supplemented by letters dated March 9, 2023 (ML23068A364), August 17, 2023 (ML23229A499), and December 14, 2023 (ML23348A375),

STP Nuclear Operating Company (STPNOC, the licensee) submitted a proposed alternative to subsection IWL 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, regarding the frequency of certain containment unbonded post-tensioning system inservice inspections at South Texas Project Units 1 and 2 (STP).

The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the licensees submittal and determined that a regulatory audit would support its review of the proposed alternative. The audit was conducted in accordance with the audit plan dated April 24, 2023 (ML23115A070).

The purpose of the audit was to review the documentation related to the subject of its application (e.g., calculations and reports) that were not submitted on the STP docket, to acquire additional understanding about the proposed alternative, and to determine whether additional information is needed to be docketed to complete the NRC staffs safety evaluation.

2.0 AUDIT ACTIVITIES

The audit was conducted via the use of an online reference portal set up by the licensee and webinars. Through the online reference portal, the NRC staff reviewed the licensees documents made available from April 27, 2023, through December 31, 2023. The August 17, 2023, supplement to the proposed alternative reflected the outcome of the audit discussions.

The NRC staff, contractors, and the licensee conducted a webinar on June 26, 2023. of this audit summary lists the individuals that took part in, or attended the audit.

The webinar discussions were focused on the following major technical areas: Clarification of apparent proposed future alternatives beyond the scope of the 35 th year proposed alternative, and methodology used for post tensioned tendon liftoff force regression analysis. At the end of the webinar on June 26, 2023, the NRC staff presented a brief conclusion of the audit discussions, including audit objectives that were met and details on the path forward. There were no open items from the audit discussions and no deviations from the audit plan.

Non-docketed information provided by the lic ensee and reviewed by the NRC staff is listed in attachment 2 of this audit summary. The licensee committed to issuing a supplement to the

Enclosure

proposed alternative to provide documentation of certain audit discussion points on the docket, which was completed with the August 17, 2023, supplement. The NRC staff reviewed the August 17, 2023, supplement and noted that th e proposed alternative discusses future proposed alternatives to ASME Code Section XI, IWL-2421(b) for the 40 th year and beyond in addition to the subject alternative request at the 35 th year. A request for additional information (RAI) was issued on November 29, 2023 ( ML23334A006), to seek clarification on the additional proposed alternatives, and the RAI was addressed in the December 14, 2023, supplement.

Since there were no remaining audit issues, the audit was closed on December 31, 2023.

3.0 RESULTS OF THE AUDIT

The audit identified information to be provided on the docket, which the licensee agreed to provide through supplements to the proposed alternative. The licensee provided the last supplement on December 14, 2023. As discussed during the audit, the supplement replaces the proposed alternative and the previous supplements in its entirety and included change bars.

Thus, those details are not included in this audit summary.

Attachments:

1. Audit Participants

2. List of Documents Reviewed During Audit Audit Participants

U.S. Nuclear Regulatory Commission Dennis Galvin Shao Lai George Wang

STP Nuclear Operating Company Wendy Brost Zachary Dibbern

Attachment 1 List of Documents Reviewed During Audit

STP Nuclear Operating Company (the licensee) provided an extensive list of supporting documents (e.g., analyses, calculations, reports, drawings, and procedures) on the South Texas Project, Units 1 and 2 (STP), document portal available during the audit period. Below lists the documents available on the portal that the U.S. Nuclear Regulatory Commission audit team reviewed during the audit.

10th Year Inservice Tendon Surveillance for Unit 1 Containment Post Tensioning System, dated November 5, 1998.

10th Year Inservice Tendon Surveillance for Unit 2 Containment Post Tensioning System, dated November 5, 1998.

Final Report for the 15th Year Post-Tensioning Surveillance, dated June 10, 2004.

Final Report South Texas Project Unit 1 Physical & Unit 2 Visual 20 th Year Containment Building Tendon Surveillance, dated April 15, 2009.

Unit 2 Containment External Concrete Inspection, dated January 5, 2011.

Final Report for the 25th Year Tendon Surveillance at STP Nuclear Generating Station, August 4, 2014.

Final Report for the Containment Structure Tendon Surveillance at South Texas Project Nuclear Power Plant Unit 1 and Unit 2 [30th year surveillance report],

dated April 19, 2018.

Regression Analysis for the Unit 1 30 th Year Tendon Surveillance at South Texas Nuclear Power Plant, dated April 19, 2018.

Attachment 2

ML24033A300 *concurrence by email OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA* NRR/DEX/ESEB/BC*

NAME DGalvin PBlechman ITseng DATE 2/6/2024 2/6/2024 1/30/2024 OFFICE NRR/DORL/LPL4/BC* NRR/DORL/LPL4/PM*

NAME JRankin DGalvin DATE 2/7/2024 2/7/2024