SUPPLEMENTARY INFORMATION:

I. Obtaining Information and Submitting Comments

A. Obtaining Information

Please refer to Docket ID NRC-2026-1453 when contacting the NRC about the availability of information for this action. You may obtain publicly available information related to this action by any of the following methods:

• Federal Rulemaking Website: Go to https://www.regulations.gov and search for Docket ID NRC-2026-1453.
• NRC's Agencywide Documents Access and Management System (ADAMS): You may obtain publicly available documents online in the ADAMS Public Documents collection at https://www.nrc.gov/​reading-rm/​adams.html. To begin the search, select “Begin ADAMS Public Search.” For problems with ADAMS, please contact the NRC's Public Document Room (PDR) reference staff at 1-800-397-4209, at 301-415-4737, or by email to PDR.Resource@nrc.gov. For the convenience of the reader, instructions about obtaining materials referenced in this document are provided in the “Availability of Documents” section.
• NRC's PDR: The PDR, where you may examine and order copies of publicly available documents, is open by appointment. To make an appointment to visit the PDR, please send an email to PDR.Resource@nrc.gov or call 1-800-397-4209 or 301-415-4737, between 8 a.m. and 4 p.m. eastern time (ET), Monday through Friday, except Federal holidays.

B. Submitting Comments

The NRC encourages electronic comment submission through the Federal rulemaking website ( https://www.regulations.gov). Please include Docket ID NRC-2026-1453 in your comment submission.

The NRC cautions you not to include identifying or contact information that you do not want to be publicly disclosed in your comment submission. The NRC will post all comment submissions at https://www.regulations.gov as well as enter the comment submissions into ADAMS. The NRC does not routinely edit comment submissions to remove identifying or contact information.

If you are requesting or aggregating comments from other persons for submission to the NRC, then you should inform those persons not to include identifying or contact information that they do not want to be publicly disclosed in their comment submission. Your request should state that the NRC does not routinely edit comment submissions to remove such information before making the comment submissions available to the public or entering the comment into ADAMS.

II. Discussion

As directed in SRM-SECY-11-0089, “Options for Proceeding with Future Level 3 Probabilistic Risk Assessment (PRA) Activities,” the staff conducted a full-scope multi-unit site Level 3 PRA (Level 3 PRA project) that addresses all internal and external hazards; all plant operating modes; and all reactor units, spent fuel pools, and dry cask storage. The reference site for this study contains 2 four-loop Westinghouse pressurized water reactors with large dry containments. The objectives of the Level 3 PRA project are to (1) develop a Level 3 PRA, generally based on current state-of-practice methods, tools, and data, that (a) reflects technical advances since the last NRC-sponsored Level 3 PRAs (NUREG-1150), which were completed over 30 years ago, and (b) addresses scope considerations that were not previously considered ( e.g., low-power and shutdown risk, multi-unit risk, other radiological sources); (2) extract new insights to enhance regulatory decision making and to help focus limited NRC resources on issues most directly related to the agency's mission to protect public health and safety; (3) enhance PRA staff capability and expertise and improve documentation practices to make PRA information more accessible, retrievable, and understandable; and (4) demonstrate technical feasibility and evaluate the realistic cost of developing new Level 3 PRAs.

The work performed under this project is being documented as a multi-volume report, commensurate with the depth and scope of this seminal research program. Over the last several years, the staff has publicly released 21 draft reports that document the various PRA models developed for the Level 3 PRA project. The current draft report (Volume 1) represents the completion of the Level 3 PRA project and provides a summary of the entire Level 3 PRA project. This includes the project scope and objectives, a brief overview of the project technical approach, and a summary of the principal project results, observations, and insights. This report also identifies existing and potential future uses of the project information, as well as a set of candidate areas for future research.

The Level 3 PRA project represents a significant research effort by the NRC and was completed in a manner consistent with the overall project objectives. The project documentation provides a complete record of project assumptions, modeling approaches, and results, which was a significant project goal. This study addressed several PRA modeling gaps, piloted newly developed approaches for expert elicitation, and included extensive peer reviews supported by the Advisory Committee on Reactor Safeguards, the Pressurized Water Reactor Owners Group, and an internal technical advisory group. Stakeholder comments received during the public comment periods for the previously released project reports further enhanced the quality of the documentation. Insights related to this work have supported regulatory decision-making in several areas and the knowledge management aspects of conducting the study have prepared the agency to address emerging PRA challenges in support of risk-informed decision-making.

III. Availability of Documents

The documents identified in the following table are available to interested persons through ADAMS, as indicated.

( printed page 29515)

(Authority: 42 U.S.C. 2011 et seq.)

91 FR 29513