ML25090A217
| ML25090A217 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 04/02/2025 |
| From: | Samson Lee Plant Licensing Branch IV |
| To: | Reasoner C Wolf Creek |
| Lee S, 301-415-3168 | |
| References | |
| EPID L-2024-LLA-0170, EPID L-2025-LLA-0017 | |
| Download: ML25090A217 (11) | |
Text
April 2, 2025 Cleveland Reasoner Chief Executive Officer and Chief Nuclear Officer Wolf Creek Nuclear Operating Corporation P.O. Box 411 Burlington, KS 66839
SUBJECT:
WOLF CREEK GENERATING STATION, UNIT 1 REGULATORY AUDIT PLAN IN SUPPORT OF LICENSE AMENDMENT REQUESTS TO ADOPT TSTF-505, REVISION 2, PROVIDE RISK-INFORMED EXTENDED COMPLETION TIMES - RITSTF INITIATIVE 4B, AND 10 CFR 50.69, RISK-INFORMED CATEGORIZATION AND TREATMENT OF STRUCTURES, SYSTEMS AND COMPONENTS FOR NUCLEAR POWER REACTORS (EPID L-2024-LLA-0170 AND EPID L-2025-LLA-0017)
Dear Cleveland Reasoner:
By letters dated December 17, 2024, and January 30, 2025 (Agencywide Documents Access and Management System (ADAMS) Accession Nos. ML24352A438 and ML25030A384, respectively), Wolf Creek Nuclear Operating Corporation (the licensee) submitted license amendment requests (LARs) to amend the license for Wolf Creek Generating Station, Renewed Facility Operating License No. NPF-42. The proposed LARs would adopt Technical Specifications Task Force (TSTF) Traveler TSTF-505, Revision 2, Provide Risk-informed Extended Completion Times - RITSTF [Risk-Informed TSTF] Initiative 4b and adopt the provisions of Title 10 of the Code of Federal Regulations 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 will conduct the audit using a licensee-established electronic portal available to staff from approximately April 21, 2025, through August 25, 2025. Formal audit meetings using video and teleconferencing will be scheduled during this period, as needed. The detailed audit plan is enclosed with this letter.
If you have any questions, please contact me by telephone at 301-415-3168 or by email to Samson.Lee@nrc.gov.
Sincerely,
/RA/
Samson S. Lee, Project Manager Plant Licensing Branch 4 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-482
Enclosures:
Audit Plan 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 AND 10 CFR 50.69 WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION, UNIT 1 DOCKET NO. 50-482
1.0 BACKGROUND
By letters dated December 17, 2024, and January 30, 2025, (References 1 and 2, respectively),
Wolf Creek Nuclear Operating Corporation (the licensee) submitted license amendment requests (LARs) to amend the license for Wolf Creek Generating Station, Unit 1, Renewed Facility Operating License No. NPF-42. The proposed LARs would adopt Technical Specifications Task Force (TSTF) Traveler TSTF-505, Revision 2, Provide Risk-informed Extended Completion Times - RITSTF [Risk-Informed TSTF] Initiative 4b (Reference 3) 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 from the 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 (Reference 4).
2.0 REGULATORY AUDIT BASIS 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 (Reference 5), 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. The staffs review will be informed by NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR [Light-Water Reactor]
Edition, Section 19.2, Review of Risk Information Used to Support Permanent Plant-Specific Changes to the Licensing Basis: General Guidance (Reference 6). The audit will assist the
NRC staff with understanding the licensees proposed programs for implementing risk-informed completion times (RICTs) for certain technical specifications 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 and in response to the licensees request, 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 view 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 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 (RMTS)
Guidelines (Reference 7).
Understand how the licensees proposed program conforms to NRC-endorsed guidance in NEI 00-04, Revision 0, 10 CFR 50.69 SSC Categorization Guideline (Reference 8),
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 (Reference 9).
Gain a better understanding of the detailed calculations, analyses, and bases underlying the LARs and confirm the NRC 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 NRC staffs evaluation of the technical acceptability of the probabilistic risk assessment (PRA) used for these applications.
Identify any information needed to enable the NRC 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 (RAIs) per NRR Office Instruction LIC-115, Processing Requests for Additional Information (Reference 10).
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 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 2 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 1 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. No information that is accessed through the licensees portal will be held or retained in any way by the staff.
5.0 AUDIT TEAM Table 1 below, 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 Samson Lee(1)
Samson.Lee@nrc.gov X
X Plant Licensing Branch LPL4 (LPL4)
Malcolm.Patterson@nrc.gov X
PRA Licensing Branch A (APLA)
April.Pulvirenti@nrc.gov X
Ching Ng Ching.Ng@nrc.gov X
X Thinh Dinh Thinh.Dinh@nrc.gov X
PRA Licensing Branch B (APLB)
Charles Moulton Charles.Moulton@nrc.gov X
Stephanie Garza Stephanie.Garza@nrc.gov X
PRA Licensing Branch C (APLC)
Daniel Silverstein Daniel.Silverstein@nrc.gov X
Sunwoo Park Sunwoo.Park@nrc.gov X
X Liliana Ramadan Liliana.Ramadan@nrc.gov X
Electrical Engineering Branch (EEEB)
Khoi Nguyen Khoi.Nguyen@nrc.gov X
X Ming Li Ming.Li@nrc.gov X
Instrumentation and Controls Branch (EICB)
Norbert Carte Norbert.Carte@nrc.gov X
Thomas Scarbrough Thomas.Scarbrough@nrc.gov X
Mechanical Engineering and Inservice Testing Branch (EMIB)
Gurjendra Bedi Gurjendra.Bedi@nrc.gov X
Yuken Wong Yuken.Wong@nrc.gov X
Cory Parker Cory.Parker@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
Containment and Plant Systems Branch (SCPB)
David Nold David.Nold@nrc.gov X
Fred Forsaty Fred.Forsaty@nrc.gov X
X Nuclear Systems Performance Branch (SNSB)
Table 1: NRC Audit Team Composition Name E-mail LAR Review Area (Organization)
RICT 50.69 Robert Elliott Robert.Elliott@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 by interviews with the licensees subject matter experts. The audit will begin within 2 weeks of the date of this audit plan.
A desktop audit will take place between approximately April 21, 2025, and August 25, 2025. 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.
7.0 SPECIAL REQUESTS The following conditions associated with the online web-based electronic portal should be maintained while the NRC staff on the 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 the NRC staff from printing, saving, downloading, or collecting any information from the web portal.
The licensee should provide username and password information directly to the NRC staff on the audit team, listed in table 1, above. The NRC project manager will provide the licensee the names and contact information of the NRC staff who are added to the audit team. 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 RAIs, as needed, in accordance with NRR LIC-115 and issue such RAIs 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 Boyce, M.T, Wolf Creek Nuclear Operating Corporation, letter to U.S. Nuclear Regulatory Commission, License Amendment Request to Revise Technical Specifications to Adopt TSTF-505-A, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF-Initiative 4b, dated December 17, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24352A438).
- 2.
Boyce, M.T., Wolf Creek Nuclear Operating Corporation, letter to U.S. Nuclear Regulatory Commission, License Amendment Request to to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors, dated January 30, 2025 (ML25030A384).
- 3.
Technical Specifications Task Force letter to the U.S. Nuclear Regulatory Commission, 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 (ML18183A493).
4 U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, LIC-101, Revision 6, License Amendment Review Procedures, July 31, 2020 (ML19248C539).
- 5.
U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, LIC-111, Revision 2, Regulatory Audits, December 30, 2024 (ML24309A281).
- 6.
U.S. Nuclear Regulatory Commission, NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition, Section 19.2, Review of Risk Information Used to Support Permanent Plant-Specific Changes to the Licensing Basis: General Guidance, June 2007 (ML071700658).
- 7.
Nuclear Energy Institute, NEI 06-09, Revision 0-A, Risk-Informed Technical Specifications Initiative 4b, Risk-Managed Technical Specifications (RMTS) Guidelines -
Industry Guidance Document, October 2012 (Package ML122860402).
- 8.
Nuclear Energy Institute, NEI 00-04, Revision 0, 10 CFR 50.69 SSC Categorization Guideline, July 2005 (ML052910035).
- 9.
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 (ML061090627).
- 10.
U.S. Nuclear Regulatory Commmission, Office of Nuclear Reactor Regulation, LIC-115, Revision 1, Processing Requests for Additional Information, August 5, 2021 (ML21141A238).
Attachment:
Audit Items List
Attachment AUDIT ITEMS LIST Item #
Audit Item 1
For probabilistic risk assessments (PRAs) cited in enclosure 2 of the license amendment request (LAR) to adopt Technical Specifications Task Force (TSTF)
Traveler TSTF-505 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24352A438), and attachment 3 of the LAR to adopt Title 10 of the Code of Federal Regulations (10 CFR) Section 50.69 (ML25030A384), reports 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 10 CFR 50.69 LARs.
- b. Identification of key assumptions and sources of uncertainty for the TSTF-505 and 10 CFR 50.69 LARs.
- c. Parametric uncertainty and state-of-knowledge correlation evaluation for the TSTF-505 and 10 CFR 50.69 LARs.
3 PRA notebooks for the modeling of digital control systems, if any, including basis for the representative failure probabilities.
4 If modeled, PRA notebooks associated with the modeling of open phase condition (OPC) in electrical switchyards and the open phase isolation system (OPIS).
5 Fire PRA notebooks containing the results of the fire PRA, including risk importance measures.
6 If not included in Item #5 above:
Fire PRA F&O closure reports Ordered list of top fire scenarios for each unit (i.e., those contributing 1 percent or more of the calculated fire risk)
Risk summary (i.e., core damage frequency (CDF) and large early release frequency (LERF)) for each fire area for each unit Fire area to physical analysis unit (PAU) crosswalk 7
Documentation supporting the screening of external flooding hazards from risk-informed completion times (RICT) and 10 CFR 50.69 categorization.
Item #
Audit Item 8
Documentation related to the high winds analysis. These include the following:
The high winds datasets obtained from the National Oceanic and Atmosphere Administration (NOAA) used to compute tornado hazard frequencies.
Notebooks/calculations for specific frequencies for straight line wind events developed from the NOAA datasets.
Notebooks/calculations related to the high wind fragility analysis and CDF/LERF penalty factors for RICT.
Notebooks/calculations related to the assessment of high winds risk in 10 CFR 50.69 categorization.
9 Documentation supporting the following related to the seismic margin analysis (SMA) for addressing risk from seismic hazards:
The current site-specific seismic hazard curve.
Notebooks/calculations related to the seismic CDF/LERF contributions.
Documentation supporting site-specific application of the Electric Power Research Institute Tier-2 alternative seismic approach to 10 CFR 50.69 categorization 10 Documentation supporting the example RICT calculations presented in LAR enclosure 1, table E1-2.
11 Documentation supporting the development of the real-time risk tool and benchmarking it against the PRA.
12 PRA configuration control and update procedures, including when the PRA is updated (i.e., unscheduled and scheduled PRA updates).
13 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.]
Item #
Audit Item 14 TSTF-505 Revision 2 (ML18183A493) PDF page 113 of 850 states:
The description of proposed changes to the protective instrumentation and control features in TS Section 3.3, Instrumentation, should confirm that at least one redundant or diverse means (other automatic features or manual action) to accomplish the safety functions (for example, reactor trip, SI [safety injection], containment isolation, etc.) remains available during use of the RICT, consistent with the defense-in-depth philosophy as specified in RG [Regulatory Guide] 1.174. (Note that for each application, the staff may selectively audit the licensing basis of the most risk-significant functions with proposed RICTs to verify that such diverse means exist.)
The LAR (ML24352A438) - See LAR PDF page 194 of 264 (LAR enclosure 1 page 20 of 33) section 3, Evaluation of Instrumentation and Control Systems, includes an evaluation to address the above; however, this evaluation is missing the table (typically supplied in TSTF-505 applications) which systematically demonstrates, for each event in chapter 15 (That is mitigated by Instrumentation and Controls (I&C) subject to RICT), the credited means and the diverse means to initiate the protective function. Please provide this table for discussion during the audit.
15 Single-line diagrams of electrical power distribution systems, load lists for safety-related loads per division/train, latest TS Basis, list of electrical shared structures, systems, and components (SSCs) between divisions/trains, if any, and associated cross-tie(s), and a description of how such shared SSCs and cross-tie(s), if any, are modeled in the Wolf Creek Generating Station, Unit 1, PRA.
16 Other documentation that the licensee determines to be responsive to the U.S.
Nuclear Regulatory Commission staffs information requests.
ML25090A217 OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA NRR/DRA/APLA/BC NAME SLee PBlechman RPascarelli DATE 3/28/2025 3/31/2025 3/26/2025 OFFICE NRR/DRA/APLB/BC NRR/DRA/APLC/BC(A)
NRR/DORL/LPL4/BC NAME EDavidson ANeuhausen (SAlferink for) TNakanishi DATE 3/28/2025 3/26/2025 4/2/2025 OFFICE NRR/DORL/LPL4/PM NAME SLee DATE 4/2/2025