A risk/safety analysis, particularly a probabilistic safety assessment (PSA), is a vital element in the development, licensing, and deployment of the next generation of nuclear power plants. The existing PSA methods and tools that were developed and successfully implemented over the last 50 years on the current fleet of large light water reactors (LWRs) may require modification to adequately assess the risks of advanced reactors. Advanced reactor designs and associated operating and safety characteristics are sufficiently different that a review of existing PSA methods is warranted. For example, many of the emerging advanced reactor designs will depend on advanced nuclear fuels and passive safety systems. Some designs will utilize coolants other than light water such as helium, liquid sodium, or molten salt; and can be designated as non-light water (NLW) plants. Some designs will also be deployed at lower power levels and can be designated as small modular reactors (SMRs). Such advances present opportunities to apply PSA in a new and optimized way but also present challenges to the existing PSA methods and approaches.

EPRI partnered with the Korea Atomic Energy Research Institute (KAERI) and their collaborators to evaluate current PSA methods and tools for their readiness to support advanced reactor designs and ensure these methods and tools can support advanced reactors through the phases of design, licensing, construction, and operation.

Based on the evaluation, it was concluded that the current methods developed and used for several elements of LWR PSAs are generally applicable for NLW-SMRs. For example, the current LWR PSA methodology appears to be suitable for initiating event identification and quantification, development and use of reliability data, and off-site probabilistic consequence analysis. However, even for these elements some potential gaps in the current methods and tools were identified. Current methods may be useful as starting points, but enhancements to the methods may be required for full implementation of a PSA.

This presentation will summarize the findings of the evaluation, including applicability to PSA elements, gaps, and possible resolutions. Additional cross-cutting issues identified during the evaluation will be discussed.