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NoticeOpen for Comment2026-170132026-08-20

Regulatory Guide: Acceptability of Probabilistic Risk Assessment Results for Non-Light Water Reactor Risk-Informed Activities

Nuclear Regulatory Commission

Abstract

The U.S. Nuclear Regulatory Commission (NRC) is issuing for trial use, Revision 1 to Trial Regulatory Guide (RG) 1.247, "Acceptability of Probabilistic Risk Assessment Results for Non-Light Water Reactor Risk-Informed Activities." This guidance describes one acceptable approach for determining whether the acceptability of the probabilistic risk assessment (PRA) used to support a PRA application is sufficient to provide confidence in the results for non-light water reactors (NLWRs) and risk-informed activities. Trial RG 1.247 was originally issued in March 2022 with a 2-year trial period that ended in May 2024. The staff is issuing Revision 1 to RG 1.247 (with minimal changes) as a trial RG so that it can continue to be used by potential applicants while the staff addresses the remaining technical issues that are best resolved by continuing to test the guide against actual applications. As a trial RG, this issuance does not provide final staff positions and the guidance within may be revised based on experience obtained by the NRC with its use after its publication.

Action & Dates

Action
Trial guide; request for comment.
Dates
Submit comments by October 19, 2026. Comments received during this public comment period will be considered and responded to. The public comment period will be followed by a 3-year trial use period. At any time during the trial use period, a member of the public may submit suggestions to the NRC for improvement of existing RGs or for the development of new RGs. Suggestions can be submitted on the NRC's public website at https://www.nrc.gov/reading-rm/doc-collections/reg- guides/contactus.html. Suggestions will be considered in future updates and enhancements to the "Regulatory Guide" series. This trial use period may be extended, as necessary, based on the experience obtained. After the trial use period, the NRC staff will develop and issue a draft RG that will include the stakeholder feedback and experience gained from use of the trial RG. The draft RG issuance will also provide an additional formal public comment opportunity, with feedback considered prior to final RG publication.

Public Comment

Comments Close
2026-10-19 — Open for comment

Document Excerpt

Document Headings Document headings vary by document type but may contain the following: the agency or agencies that issued and signed a document the number of the CFR title and the number of each part the document amends, proposes to amend, or is directly related to the agency docket number / agency internal file number the RIN which identifies each regulatory action listed in the Unified Agenda of Federal Regulatory and Deregulatory Actions See the Document Drafting Handbook for more details. Nuclear Regulatory Commission [NRC-2022-0052] AGENCY: Nuclear Regulatory Commission. ACTION: Trial guide; request for comment. SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing for trial use, Revision 1 to Trial Regulatory Guide (RG) 1.247, “Acceptability of Probabilistic Risk Assessment Results for Non-Light Water Reactor Risk-Informed Activities.” This guidance describes one acceptable approach for determining whether the acceptability of the probabilistic risk assessment (PRA) used to support a PRA application is sufficient to provide confidence in the results for non-light water reactors (NLWRs) and risk-informed activities. Trial RG 1.247 was originally issued in March 2022 with a 2-year trial period that ended in May 2024. The staff is issuing Revision 1 to RG 1.247 (with minimal changes) as a trial RG so that it can continue to be used by potential applicants while the staff addresses the remaining technical issues that are best resolved by continuing to test the guide against actual applications. As a trial RG, this issuance does not provide final staff positions and the guidance within may be revised based on experience obtained by the NRC with its use after its publication. DATES: Submit comments by October 19, 2026. Comments received during this public comment period will be considered and responded to. The public comment period will be followed by a 3-year trial use period. At any time during the trial use period, a member of the public

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Full Document

Citation: 91 FR 53903