ML25262A058
| ML25262A058 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 12/12/2025 |
| From: | Shawn Williams Plant Licensing Branch II |
| To: | Huecker J Duke Energy Carolinas |
| Stone Z | |
| References | |
| EPID L-2025-LLA-0XXX TSTF 505 | |
| Download: ML25262A058 (0) | |
Text
December 12, 2025 Mr. Jonathan Huecker Site Vice President Catawba Nuclear Station Duke Energy Carolinas, LLC 4800 Concord Road York, SC 29745
SUBJECT:
CATAWBA NUCLEAR STATION, UNITS 1 AND 2-REGULATORY AUDIT IN SUPPORT OF LICENSE AMENDMENT REQUESTS TO ADOPT TSTF 505, REVISION 2, PROVIDE RISK-INFORMED EXTENDED COMPLETION TIMES -
RITSTF INITIATIVE 4B, TSTF-591, REVISION 0, REVISE RISK INFORMED COMPLETION TIME (RICT) PROGRAM AND 10 CFR 50.69, RISK-INFORMED CATEGORIZATION AND TREATMENT OF STRUCTURES, SYSTEMS AND COMPONENTS FOR NUCLEAR POWER REACTORS (EPIDS L-2025-LLA-0155 AND L-2025-LLA-0156)
Dear Mr. Huecker:
By letters dated September 30, 2025 (Agencywide Documents Access and Management System (ADAMS) Accession Nos. ML25273A162 and ML25273A166), respectively, Duke Energy Carolinas, LLC (the licensee) submitted license amendment requests (LARs) to amend the licenses and technical specifications (TS) for Catawba Nuclear Station, Units 1 and 2, Renewed Facility Operating License Nos. NPF-35 and NPF-52, respectively. The proposed LARs would adopt Technical Specifications Task Force Traveler 505, Revision 2, Provide Risk-informed Extended Completion Times, RITSTF Initiative 4b (TSTF 505), TSTF-591, Revision 0, "Revise Risk Informed Completion Time (RICT) Program, and adopt the provisions of Title 10 of the Code of Federal Regulations (10 CFR), Section 50.69, Risk-informed categorization and treatment of structures, systems and components for nuclear power reactors.
The U.S. Nuclear Regulatory Commission (NRC) staff has identified the need for a regulatory audit to examine the licensees non-docketed information with the intent to gain understanding, to verify information, or to identify information that will require docketing to support the basis of the licensing or regulatory decision.
The NRC staff plans to conduct the audit virtually through Microsoft Teams using a licensee-established electronic portal accessible to NRC staff from December 2025 through March 2026. Formal audit meetings will be scheduled during this period, as needed. The detailed audit plan is enclosed with this letter.
The NRC staff will issue an audit summary after the completion of the audit.
If you have any questions, please contact me at Shawn.Williams@nrc.gov.
Sincerely,
/RA/
Shawn A. Williams, Senior Project Manager Plant Licensing Branch II 1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos.
50-413, 50-414
Enclosures:
- 1. Regulatory Audit Plan
- 2. Audit Questions for Discussion cc: Listserv
REGULATORY AUDIT PLAN BY THE OFFICE OF NUCLEAR REACTOR REGULATION TO SUPPORT THE REVIEW OF LICENSE AMENDMENT REQUESTS TO ADOPT RISK INFORMED COMPLETION TIMES - TSTF-505, REVISE THE RISK INFORMED COMPLETION TIME PROGRAM - TSTF-591, AND ADOPT 10 CFR 50.69 RISK-INFORMED CATEGORIZATION OF SSCs DUKE ENERGY CAROLINAS, LLC CATAWBA NUCLEAR STATION, UNITS 1 AND 2 DOCKET NOS. 50-413 AND 50-414
1.0 BACKGROUND
By letters dated September 30, 2025 [1] [2], Duke Energy Carolinas, LLC (the licensee) submitted license amendment requests (LARs) for Catawba Nuclear Station, Units 1 and 2 (Catawba). Reference 1 would modify the Catawba Technical Specifications (TSs) to permit the use of Risk-Informed Completion Times (RICTs) in accordance with Technical Specifications Task Force (TSTF) Traveler - 505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b [3] and TSTF-591, Revision 0, Revise Risk Informed Completion Time (RICT) Program [4]. Reference 2 proposes the addition of a license condition that allows implementation of the provisions in Title 10 of the Code of Federal Regulations (10 CFR),
Section 50.69, Risk Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors.
The staff from the Nuclear Regulatory Commissions(NRCs) Office of Nuclear Reactor Regulation(NRR) has initiated its review of the LARs in accordance with NRR Office Instruction LIC-101, License Amendment Review Procedures [5].
2.0 REGULATORY AUDIT BASES A regulatory audit is a planned license, or regulation-related activity that includes the examination and evaluation of the licensees non-docketed information that provides the technical basis for the LAR. An audit is conducted to gain understanding, to verify information, and to identify information that will require docketing to support the basis of a licensing or regulatory decision. An audit will assist the NRC staff in efficiently conducting its review and gaining insights to the licensees processes and procedures. Information that the NRC staff relies upon to make the safety determination must be submitted on the docket. This audit will be conducted in accordance with NRR LIC-111, Regulatory Audits [6], with exceptions noted within this audit plan.
The NRC staff will perform the audit to support its evaluation of whether the licensees requests can be approved per 10 CFR 50.90, Application for amendment of license, construction permit, or early site permit, and 10 CFR 50.36, Technical specifications. The staffs review will be informed by Standard Review Plan Section 19.2, Review of Risk Information Used to Support Permanent Plant-Specific Changes to the Licensing Basis [7]. The audit will assist the NRC staff with understanding the licensees proposed programs for implementing RICTs for certain TSs and categorizing structures, systems, and components (SSCs) based on their risk significance. Further, due to the overlaps in technical matter and personnel reviewing the two LARs, the NRC staff determined that a combined audit would permit the most efficient use of resources for the NRC and the licensee.
3.0 SCOPE The audit team will review the documentation and calculations that provide the technical support for the LARs. The scope of the NRC staffs audit will focus on the following subjects:
Understand how the licensees proposed program implements TSTF-505 and TSTF-591 and conforms to NRC-endorsed guidance in the Nuclear Energy Institute (NEI) report NEI 06-09, Revision 0-A, Risk-Informed Technical Specifications Initiative 4b, Risk-Managed Technical Specifications Guidelines [8].
Understand how the licensees proposed program conforms to NRC-endorsed guidance in NEI 00-04, Revision 0, 10 CFR 50.69 SSC Categorization Guideline [9], as endorsed by Regulatory Guide 1.201, Revision 1, Guidelines for Categorizing Structures, Systems, and Components in Nuclear Power Plants According to Their Safety Significance [10].
Gain a better understanding of the detailed calculations, analyses, and bases underlying the LARs and confirm the staffs understanding of the LARs.
Gain a better understanding of plant design features and their implications for the LARs.
Identify any information needed to enable the staffs evaluation of the technical acceptability of the probabilistic risk assessment (PRA) used for these applications.
Identify any information needed to enable the staffs evaluation of whether the proposed changes challenge design-basis functions or adversely affect the capability or capacity of plant equipment to perform design-basis functions.
Identify questions and requests that may become formal requests for additional information (RAI) per NRR Office Instruction LIC-115, Processing Requests for Additional Information [11].
The NRC staff will audit the PRA methods that the licensee would use to: (1) categorize SSCs based on their risk significance, and (2) determine the risk impact from which the revised completion times for TSTF-505 would be obtained. This will include the licensees assessment of internal events (including internal flooding) and fire as well as the treatment of uncertainties and evaluation of defense in depth. The NRC will also audit the licensees quantification of risk from significant external events, whether the licensee uses PRA or bounding methods. In addition, the audit team will discuss these topics with the licensees subject matter experts.
4.0 INFORMATION AND OTHER MATERIAL NECESSARY FOR THE REGULATORY AUDIT The NRC staff will request information and interviews throughout the audit period. The NRC staff will use an audit items list to identify the information to be audited (e.g., methodology, process information, and calculations) and the subjects of requested interviews and meetings.
The NRC staff requests the licensee to have the information referenced in the attachment of this audit plan available and accessible for the NRC staffs review via a web-based electronic portal within two weeks of the date of this audit plan. The NRC staff requests that any supplemental information requested be available and accessible for the NRC staffs review within one week of the date of the NRCs notification to the licensee of the new requests. The NRC staff requests the licensee to notify the review team when an audit item is added to its electronic portal by sending an email to the NRC licensing project manager.
The NRC staff acknowledges and will observe appropriate handling and protection of proprietary information made available for the audit. Any information accessed through the licensees portal will not be held or retained in any way by NRC staff.
5.0 AUDIT TEAM The following table identifies the NRC audit team members and their respective focus areas:
Table 1: NRC Audit Team Composition Name E-mail LAR Review Area (Organization)
RICT 50.69 Shawn Williams (1)
Shawn.Williams@nrc.gov X
X Plant Licensing Branch LPL II-1 (LPL2-1)
Adrienne Brown (2)
Adrienne.Driver@nrc.gov X
X PRA Licensing Branch A (APLA)
Todd Hilsmeier Todd.Hilsmeier@nrc.gov X
X Michael Swim Michael.Swim@nrc.gov X
X PRA Licensing Branch C (APLC)
Keith Tetter Keith.Tetter@nrc.gov X
X Darrell Murdock Darrell.Murdock@nrc.gov X
Electrical Engineering Branch (EEEB)
Edmund Kleeh Edmund.Kleeh@nrc.gov X
X Jason English Jason.English@nrc.gov X
Instrumentation and Controls Branch (EICB)
Ming Li Ming.Li@nrc.gov X
X Kaihwa Hsu Kaihwa.Hsu@nrc.gov X
X Mechanical Engineering and Inservice Testing Branch (EMIB)
Dan Widrevitz Dan.Widrevitz@nrc.gov X
Vessels and Internals Branch (NVIB)
Stephen Cumblidge Stephen.Cumblidge@nrc.
gov X
Piping and Head Penetrations (NPHP)
Angelo Stubbs Angelo.Stubbs@nrc.gov X
X Containment and Plant Systems Branch (SCPB)
Rob Atienza Rob.Atienza@nrc.gov X
X Table 1: NRC Audit Team Composition Name E-mail LAR Review Area (Organization)
RICT 50.69 Fred Forsaty Fred.Forsaty@nrc.gov X
Nuclear Systems Performance Branch (SNSB)
Andrea Russell Andrea.Russell@nrc.gov X
Technical Specifications Branch (STSB)
Notes:
(1) NRR Division of Operating Reactor Licensing Project Manager (2) Technical Lead 6.0 LOGISTICS The audit will be conducted using a secure, online electronic portal, established by the licensee to present supporting documentation and calculations and discussions with the licensees subject matter expert. The audit will begin approximately December 2025 and last through March 2026.
The NRCs licensing project manager will inform the licensee of the entrance and exit meeting dates when they are established. The NRC project manager will coordinate with the licensee to set dates and times to discuss information needs and questions arising from the NRCs review of the audited items. The NRC staff may change and/or add audit dates and times when deemed necessary. Audit meeting agenda and questions will be sent in advance of the audit meeting.
The NRC staff does not expect to conduct an in-person audit meeting; however, if the staff determines that one is necessary, the project manager will inform the licensee.
7.0 SPECIAL REQUESTS The following conditions associated with the online web-based electronic portal should be maintained while the NRC staff audit team have access to the online portal:
The online electronic portal will be password-protected, and separate passwords will be assigned to each member of the audit team.
The online web-based electronic portal will be sufficiently secure to prevent members of the audit team from printing, saving, downloading, or collecting any information from the web portal.
Conditions of use of the online electronic portal will be displayed on the login screen and will require acknowledgment by each user.
The licensee should provide username and password information directly to each member of the audit team, listed above. The NRC project manager will provide the the names and contact information of each member of the audit team to the licensee. All other communications should be coordinated with the NRC project manager. The NRCs project manager will inform the licensee via routine communications when the NRC staff no longer needs access to the electronic portal.
No data accessed by the audit team members will be retained by the NRC following the conclusion of the audit.
8.0 DELIVERABLES The NRC staff will develop any RAI, as needed, in accordance with NRR LIC-115 [11] and issue such RAI separate from audit-related correspondence. The NRC staff will issue an audit summary report within approximately 90 days after the end of the audit and prior to completing its safety evaluations of the LARs.
9.0 REFERENCES
[1]
Huecker, Jonathan D., Duke Energy Carolinas, LLC, Catawba Nuclear Station, Units 1 and 2 - letter to U.S. Nuclear Regulatory Commission, License Amendment Request to Revise Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b and TSTF-591, Revision 0, Revise the Risk Informed Completion Time (RICT)
Program, September 30, 2025 (ADAMS Accession No. ML25273A162).
[2]
Huecker, Jonathan D., Duke Energy Carolinas, LLC, Catawba Nuclear Station, Units 1 and 2 - letter to U.S. Nuclear Regulatory Commission, Application to Adopt 10 CFR 50.69, Risk-informed categorization and treatment of structures, systems and components for nuclear power reactors, September 30, 2025 (ADAMS Accession No. ML25273A166).
[3]
Technical Specifications Task Force (TSTF) - A Joint Owners Group Activity, TSTF Comments on Draft Safety Evaluation for Traveler TSTF 505, Provide Risk-Informed Extended Completion Times, and Submittal of TSTF-505, Revision2, July 2, 2018 (ADAMS Accession No. ML18183A493).
[4]
Technical Specifications Task Force Traveler TSTF-591, Revise Risk Informed Completion Time (RICT) Program, March 22, 2022 [letter] and September 21, 2023
[final safety evaluation] (ADAMS Accession Nos. ML22081A224 and ML23262B230).
[5]
U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, LIC-101, Revision 6, License Amendment Review Procedures, July 31, 2020 (ADAMS Accession No. ML19248C539).
[6]
U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, LIC-111, Revision 2, Regulatory Audits, December 30, 2024 (ADAMS Accession No. ML24309A281).
[7]
U.S. Nuclear Regulatory Commission, NUREG-0800 - Standard Review Plan:
Section 19.2, Review of Risk Information Used to Support Permanent Plant-Specific Changes to the Licensing Basis: General Guidance, June 2007 (ADAMS Accession No. ML071700658).
[8]
Nuclear Energy Institute (NEI), NEI 06-09, Revision 0-A, Risk-Informed Technical Specifications Initiative 4b, Risk-Managed Technical Specifications (RMTS) Guidelines -
Industry Guidance Document, October 2012 (ADAMS Package Accession No. ML122860402).
[9]
Nuclear Energy Institute (NEI), NEI 00-04, Revision 0, 10 CFR 50.69 SSC Categorization Guideline, July 2005 (ADAMS Accession No. ML052910035).
[10]
U.S. Nuclear Regulatory Commission, Regulatory Guide 1.201, Revision 1, Guidelines for Categorizing Structures, Systems, and Components in Nuclear Power Plants According to Their Safety Significance, May 2006 (ADAMS Accession No. ML061090627).
[11]
U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, LIC-115, Revision 1, Processing Requests for Additional Information, August 5, 2021 (ADAMS Accession No. ML21141A238).
ITEM AUDIT REQUEST 1
Reports cited in Enclosure 2 of the LAR to adopt TSTF-505 and Section 3 of the LAR to adopt 10 CFR 50.69 from full-scope and focused-scope peer reviews, self-and gap assessments (including findings, observations, and dispositions), and closure reviews of facts and observations (F&Os).
2 For the PRAs identified under Item #1 above, plant-specific documentation (e.g., uncertainty notebooks) related to:
- a. The review of the PRA model assumptions and sources of uncertainty (generic and plant-specific assumptions/uncertainties) for the TSTF-505 and 50.69 LARs.
- c. Parametric uncertainty and state-of-knowledge correlation evaluation for the TSTF-505 and 50.69 LARs.
3 PRA notebooks for the modeling of FLEX equipment and FLEX human error probabilities credited in the PRAs.
4 PRA notebooks for the modeling of digital control systems, including basis for the representative failure probabilities.
5 If modeled, PRA notebooks associated with the modeling of open phase condition (OPC) in electrical switchyards and the open phase isolation system (OPIS).
6 Documentation of how shared or cross-tied systems are modeled in the PRA.
7 Fire PRA notebooks containing the results of the fire PRA, including risk importance measures.
8 10 CFR 50.69 LAR non-docketed Attachment 4 references 3, 4, 9, and 11.
9 TSTF-505 LAR non-docketed references 16, 20, 21, 23, 30, 33, 41, and 43.
10 Catawba high winds PRA information:
- a. Results of all high wind PRA full-scope and focused-scope peer reviews, self-and gap assessments (including findings, observations, and dispositions), and closure reviews of facts and observations (F&Os) performed in the year 2012 or later.
- b. High winds PRA notebooks containing the results of the high winds PRA, including risk importance measures and a description of sources of model uncertainty.
11 Documentation supporting the example risk-informed completion times (RICT) calculations presented in LAR Enclosure 1, Table E1-2.
12 Documentation supporting the development of the real-time risk tool and benchmarking it against the PRA.
ITEM AUDIT REQUEST 13 PRA configuration control and update procedures, including when the PRA is updated (i.e., unscheduled and scheduled PRA updates).
14 If available, final RICT program procedures (e.g., for risk management actions, PRA functionality determination, and recording limiting conditions for operation). [The licensee may choose (optional) to provide draft RICT program procedures if final procedures are not available.]
15 Design documentation:
- a. Simplified one-line diagrams for alternating current (AC) and direct current (DC) power distribution systems
- b. Normal and emergency lineups for AC sources and distribution systems
- c. Offsite primary and secondary feeds and any other possibilities
- d. Normal and emergency lineups for DC sources and distribution systems
- e. Information on required engineered safety feature (ESF) buses
- f.
Information on ESF bus tie-breakers (e.g., when used and under what
- g. conditions)
- h. Information on diesel generators buses, loads, and supporting systems (e.g.,
- i.
when required, minimum required for each unit etc.)
- j.
Load list
- k. List of any loads shared in the AC distribution systems
- l.
List of any loads shared in the DC distribution systems
ML25262A058 OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DRA/APLA/BC NAME SWilliams KZeleznock MGonzalez DATE 12/10/2025 12/11/2025 12/12/2025 OFFICE NRR/DORL/LPL2-1/BC NRR/DORL/LPL2-1/PM NAME MMarkley SWilliams DATE 12/12/2025 12/12/2025