ML25156A350
| ML25156A350 | |
| Person / Time | |
|---|---|
| Site: | 05000614, 99902130 |
| Issue date: | 06/11/2025 |
| From: | Stephen Philpott Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| EPID L-2025-CPS-0000 | |
| Download: ML25156A350 (1) | |
Text
LONG MOTT ENERGY, LLC - PLAN FOR AN AUDIT OF THE PROBABILISTIC RISK ASSESSMENT AND ASSOCIATED INFORMATION FOR THE LONG MOTT GENERATING STATION CONSTRUCTION PERMIT APPLICATION (EPID NO.: L2025CPS0000)
Applicant:
Long Mott Energy, LLC Applicant Address:
530 Gaither Road, Suite 700 Rockville, MD 20850 Plant Name and Units:
Long Mott Generating Station (4 units)
Docket No.:
50614
Background:
By letter dated March 31, 2025, (Agencywide Documents Access and Management System (ADAMS) Package Accession No. ML25090A057) Long Mott Energy, LLC (LME), submitted a construction permit (CP) application and corresponding preliminary safety analysis report (PSAR) to the U.S. Nuclear Regulatory Commission (NRC) for a reactor facility pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Domestic Licensing of Production and Utilization Facilities, and section 103, Commercial Licenses, of the Atomic Energy Act of 1954, as amended. The facility, referred to as Long Mott Generating Station (LMGS), would be built in Calhoun County, Texas. On May 12, 2025 (ML25115A247), the NRC staff accepted LMEs CP application for docketing. A notice of the acceptance for docketing was published in the Federal Register on May 16, 2025 (90 FR 21080). The NRC staff is conducting a detailed review of the LMGS CP application. This regulatory audit will aid the NRC staff in its review of the LMGS CP application.
Purpose:
The purpose of the audit is for the NRC staff to gain a more detailed understanding of the LMGS probabilistic risk assessment (PRA). The audit aims to improve review efficiency by allowing NRC staff to discuss supporting material, enhancing communication and reducing unnecessary requests for additional information. If the NRC staff identifies information needed to support a regulatory finding pertaining to the review of the CP application, LME will need to submit that information on the application docket.
The PRA is the plant model that provides an integrated assessment of risk to the public from the nuclear powerplant. A technically acceptable PRA is essential for implementing the risk-informed and performance-based (RIPB) methodology in Regulatory Guide (RG) 1.233, Guidance for a Technology-Inclusive, Risk-Informed, and Performance-Based Methodology to June 11, 2025 Inform the Licensing Basis and Content of Applications for Licenses, Certifications, and Approvals for Non-Light-Water Reactors, (ML20091L698). RG 1.233 endorses Nuclear Energy Institute (NEI) 1804, Revision 1, Risk-informed Performance-Based Technology Guidance for Non-Light-Water Reactors, with clarifications. The PRA is summarized in PSAR section 3.1, Probabilistic Risk Assessment, and its results as applied to the RIPB methodology are also included in other PSAR Chapters.
Regulatory Audit Basis:
The regulatory audit focuses on PRA-related information in the application. The applicable regulatory requirements include:
Section 50.34, Contents of applications; technical information, of 10 CFR and Section 50.35, Issuance of construction permits, of 10 CFR.
Regulatory Audit Scope:
This audit will focus on information provided by LME in the electronic reading room (eRR) and during meetings and interactions with LME. Future correspondence, such as emails, will outline specific objectives and discussion topics, along with proposed dates for reviewing the information.
Information and Other Material Necessary for the Regulatory Audit:
LME should make available the supporting PRA records documented in the PSAR. The NRC staff asks that the following PSAR references be ready at the start of the audit:
PSAR section 3.1.1.1, Approach to PRA Acceptability, states that, A separate analysis using this process was performed on the LMGS plant to justify deviations from or alternatives to Tables A-2 [Non-LWR CP Applications Based on the LMP Methodology:
Applicability of ASME/ANS Non-LWR PRA Standard High-Level Requirements and Supporting Requirements to PRA Elements Used to Develop a Minimally Acceptable PRA] and A-3 [Non-LWR CP Applications Based on the LMP Methodology:
Applicability of ASME/ANS Non-LWR PRA Standard High-Level Requirements and Supporting Requirements to Additional PRA Elements of RG 1.253, Guidance for a Technology-Inclusive Content of Application Methodology to Inform the Licensing Basis and Content of Applications for Licenses, Certifications, and Approvals for Non-Light-Water Reactors, appendix A, Acceptability of a Probabilistic Risk Assessment That Supports a Non-Light-Water Reactor Construction Permit Application Based on the Licensing Modernization Project Methodology]. This alternative analysis is available in plant records.
The NRC staff requests that the alternative analysis described in PSAR section 3.1.1.1, be made available to enable their understanding of the deviations from or alternatives to tables A-2 and A-3 of RG 1.253, Appendix A.
PSAR section 3.1.1.1 states that, Items outside the scope of the PRA were assessed using different requirements than those in the ASME/ANS non-LWR PRA Standard. The integrated decision-making process was used to review screening analyses, risk-informed supplemental evaluations, and credit for design basis hazard levels (DBHLs) to evaluate if radiological sources, plant operating states, and hazards were comprehensively addressed.
The NRC staff requests that integrated decision-making process documentation related to the self-assessment be made available to enable their understanding of the process used to evaluate whether radiological source, plant operating states, and hazards were comprehensively addressed as described in PSAR section 3.1.1.1.
PSAR section 3.1.1.1 states that, The PRA self-assessment process, results, and gap assessments are documented in plant records. The NRC requests that these records be made available to enable their understanding of the PRA self-assessment process and gap assessments as described in PSAR section 3.1.1.1.
Section 3.1.1.2 states Scope of the PRA, states that, The PRA performs hazard screening analysis for determination for the scope of DBHLs needed for the site. The following hazard groups are screened in for DBHL assessment and/or hazard PRA modeling:
Internal fires Internal floods High winds Seismic events External flooding The NRC staff requests that documentation of the hazard screening be made available to enable their understanding of the DBHL scope determined for the site as described in PSAR section 3.1.1.2.
Further information requests and discussion items will be provided separately throughout the audit.
Team Assignments:
Denise McGovern Senior (Sr.) Project Manager, Audit Lead Adrian Muniz Sr. Project Manager, Lead Project Manager Timothy Drzewiecki Sr. Reactor Systems Engineer, Lead Technical Reviewer Ian Jung Sr. Reliability and Risk Analyst Kristy Bucholtz Nuclear Engineer Santosh Bhatt Sr. Nuclear Engineer Tracy Radel Sr. Nuclear Engineer Zachary Gran Reactor Scientist-Severe Accidents Additional audit team members may be added, as needed.
Logistics:
Entrance Meeting:
June 16, 2025 Exit Meeting:
January 2026; precise date, and time are to be determined The audit will follow the guidance in the Office of Nuclear Reactor Regulations (NRRs) Office Instruction LIC-111, Revision 2, Regulatory Audits, (ML24309A281). Audit meetings will take place mainly in a virtual format, using Microsoft Teams or another similar platform. Audit meetings will be scheduled as needed after the entrance meeting. The audit will begin on June 16, 2025, and continue as necessary, with activities occurring intermittently during the audit period. The audit period may be reduced or extended, depending on the progress made by the NRC staff and LME in addressing audit questions.
To improve the efficiency of the audit, LME and the NRC staff will use an eRR, established by LME that will allow the NRC staff read-only access to the technical information provided by LME. Use of the eRR is acceptable provided that LME limits access to specific NRC staff (e.g.,
based on NRC email addresses or the use of passwords which will only be assigned to the NRC staff directly involved in the audit on a need-toknow basis), and to make the documents view-only (i.e., to prevent the NRC staff from saving, copying, downloading, or printing any documents). The conditions associated with the eRR must be maintained throughout the audit process. The NRC audit project managers will provide LME with the names of the NRC staff audit team that will require access to eRR.
Special Requests:
The NRC staff requests that LME subject matter experts are available to answer questions during the audit. LME should track the NRC staffs audit questions and make the responses available in the eRR. If any changes, such as PSAR revisions, are identified during the audit, the NRC staff requests LME to share the draft in the eRR for discussion before formal submission.
Deliverables:
The NRC staff will issue an audit summary within 90 days after the exit meeting. The summary will be publicly available in ADAMS.
If you have any questions related to this audit, please contact Denise McGovern at 3014150681 or via email at Denise.McGovern@nrc.gov.
Date: June 11, 2025 Stephen Philpott, Acting Chief Advanced Reactor Licensing Branch 2 Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation Docket No.: 50614 cc: Long Mott Energy, LLC via GovDelivery svaughn@xenergy.com jmaddocks@xenergy.com oconnocr@dow.com mfeltner@dow.com Signed by Philpott, Stephen on 06/11/25
ML25156A350 NRR106 OFFICE NRR/DANU/UAL2:PM NRR/DANU/UAL2:LA NRR/DANU/UTB2:BC NAME DMcGovern CSmith SPhilpott DATE 06/06/2025 06/09/2025 06/09/2025