Preferable Applications of Best-Estimate Plus Uncertainty Under a Technology-Inclusive, Risk-Informed Nuclear Plant Safety Case

The U.S. Nuclear Regulatory Commission (NRC) is actively updating its regulatory framework with industry stakeholder input under a program called the Licensing Modernization Project (LMP). Improvements are expected to better align the reactor licensing process with the needs of advanced reactor technologies by adopting technology-inclusive language, reducing prescriptive rules, and expanding the role of risk-informed and performance-based issue resolution.

This paper presents a technology-inclusive evaluation model that integrates both risk-based and deterministic features, drawing on data from historical licensing practices, U.S. and international safety standards, and industry case studies. The safety case content of a risked-informed safety analysis report (SAR), such as one consistent with the LMP model in the United States, is expected to logically connect risk insights with the resolution of safety and technical issues. While a mix of deterministic safety and quantitative risk-based evaluation models is explicitly addressed in the NRC’s draft rule [Code of Federal Regulations, Title 10, “Energy,” Part 53, “Risk Informed, Technology-Inclusive Regulatory Framework for Advanced Reactors” (10 CFR 53)], this paper identifies preferred applications for best-estimate plus uncertainty evaluation models in risk-informed SARs for safety margin management, supporting streamlined regulatory review for advanced reactor technologies.