Endorsement of ASME/ANS RA-S-1.4 Probabilistic Risk Assessment Standard for Advanced Non-Light Water Reactor Nuclear Power Plants

The advanced non-light water reactor PRA standard, ASME/ANS RA-S-1.4-2021, “Probabilistic Risk Assessment Standard for Advanced Non-Light Water Reactor Nuclear Power Plants,” was issued in February 2021 by the American Society of Mechanical Engineers and the American Nuclear Society.

On March 21, 2022, the NRC staff issued its endorsement of the standard as Trial Regulatory Guide 1.247  “Acceptability of Probabilistic Risk Assessment Results for Advanced Non-Light Water Reactor Risk-Informed Activities”.  This new guidance describes one acceptable approach for determining whether the acceptability of the PRA used to support a PRA application is sufficient to provide confidence in the results for non-light water reactors and risk-informed activities. This RG also provides endorsement of industry guidance on non-LWR PRA peer reviews, NEI 20-09, "Performance of PRA Peer Reviews Using the ASME/ANS Advanced Non-Light Water Reactor Standard."  As a trial RG, this issuance does not provide final staff positions and the guidance may be revised based on experience obtained by the NRC with its use after its publication. Comments submitted by May 24, 2022, will be considered and responded to. The public comment period will be followed by a 2-year trial use period. At any time during the trial use period, suggestions for improvement can be submitted on the NRC’s public website.

Page Last Reviewed/Updated Wednesday, March 30, 2022