NRC seeks public input on Level 3 PRA project

April 28, 2022, 12:00PMNuclear News

The Nuclear Regulatory Commission is seeking input from the public regarding the first set of results from its multiyear Level 3 Probabilistic Risk Assessment Project to analyze risk at a reference two-reactor nuclear power plant site.

The project, which began in 2012, updates risk insights obtained from work done more than 30 years ago, according to the NRC. The project examines a reference site with two large pressurized water reactors and associated spent fuel. It builds on Level 1 (possible reactor core damage scenarios) and Level 2 (possible radioactive material release scenarios) analyses to estimate potential health effects and economic impacts.

Safety issues: The NRC combines PRA results with traditional engineering methods when regulating nuclear power plants and other civilian uses of radioactive material. The agency uses PRA insights to focus its efforts on the issues most important to safety. It also uses PRA to confirm that new or revised rules are rigorous enough to cover uncertainties and to justify new requirements. Nuclear power plants use PRA to discover and correct subtle vulnerabilities, such as in fire protection, significantly improving reactor safety, according to the NRC. It can also inform regulatory, policy, and technical issues pertaining to advanced and new reactors.

Spaced reviews: The staff is issuing project results in batches to allow for a thorough review by the agency’s independent Advisory Committee on Reactor Safeguards (ACRS). The first set of results, covering in-plant events and flooding while the reactors are at full power, make up Volume 3 of the project’s eventual final report. Volume 3’s analysis, considering the reference site’s design and location, shows that the potential public effects of a reactor accident fall well below the agency’s stringent health and safety goals, according to the NRC. The agency’s staff is expected to continue releasing portions of the project for public and ACRS review through early 2024.

Public comments: NRC staff will consider written comments on Volume 3x (and other background material) until June 21, following the publication of a notice in the April 22 Federal Register. Comments should include Docket ID NRC-2022-0085 and can be submitted via or by mail to Office of Administration, Mail Stop: TWFN 7 A60M, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001.

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