SUPPLEMENTARY INFORMATION:

I. Obtaining information and Submitting Comments

A. Obtaining Information

Please refer to Docket ID NRC-2026-3268 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 www.regulations.gov and search for Docket ID NRC-2026-3268.
• NRC's Agencywide Documents Access and Management System (ADAMS): You may obtain publicly available documents online in the ADAMS Public Documents collection at 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. The draft ISG, “Evaluations of Risk Assessments for Risk-Informed Decision-Making for Regulatory Applications” is available in ( printed page 54410) ADAMS under Accession No. ML26162A452.
• 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 ( www.regulations.gov). Please include Docket ID NRC 2026-3268 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 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

The NRC is anticipating a high volume of license applications for new and advanced reactors. Many new applications are expected to leverage risk assessments to establish the safety of facility designs that can be operated without undue risk to the health and safety of the public. This ISG will supplement existing guidance to support staff in assessing how risk information is used in applications, determining the acceptability of risk assessments, and integrating risk insights into licensing decisions.

The NRC has historically recognized the value of risk assessment in regulatory decision making, as reflected in the Commission's Final Policy Statement on Use of Probabilistic Risk Assessment Methods in Nuclear Regulatory Activities (60 FR 42622). Many of the concepts and terms related to using PRAs, risk insights, and risk-informed processes in regulatory activities are described in the Commission Staff Requirements Memorandum, SRM-SECY-98-144, “Staff Requirements—SECY-98-144—White Paper on Risk-Informed and Performance-Based Regulation.” Implementing the use of PRA methods has been supported by the issuance of regulatory guidance, including Regulatory Guide (RG) 1.174, which describes an approach for using PRA in risk-informed decisions on plant-specific changes to the licensing basis, and RGs 1.200 and 1.247 (for trial use), which provided guidance on acceptability of PRAs for light-water reactors (LWRs) and non-LWRs, respectively.

This ISG provides staff guidance on evaluating risk assessment methods, including PRAs and SREs. This ISG provides guidance on evaluating the characteristics and attributes of a risk assessment using a flexible approach that can accommodate a range of risk-informed applications. This ISG builds upon, and aligns with, the risk-informed decision-making principles of RG 1.174 to consider a risk assessment along with other factors to determine its acceptability in the context of its uses to support an application. This ISG leverages the high-level approach discussed in RGs 1.200 and 1.247 (for trial use) and considers acceptability of a risk assessment in terms of establishing the analysis scope, providing an adequate level of detail, demonstrating use of acceptable methods, and ensuring representation of the facility. While these considerations were identified in the context of development of a PRA guided by a consensus standard, the same considerations can be broadly applied to other risk assessment methods.

This ISG is applicable to the review of applications for permits and licenses that submit risk-informed, performance-based applications for construction permits (CPs) or operating licenses (OLs) under part 50 of title 10 of the Code of Federal Regulations (10 CFR); for combined operating licenses (COLs), standard design approvals (SDAs), design certifications (DCs) or manufacturing licenses (MLs) under 10 CFR part 52; or CP, OL, COL, custom COL, SDA, DC, or ML under 10 CFR part 53.

III. Executive Order (E.O.) 12866

The Office of Information and Regulatory Affairs determined that draft ISG, “Acceptability of Risk Assessments for Risk-Informed Decision-Making for Regulatory Applications,” is not a significant regulatory action under E.O. 12866.

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

91 FR 54409