The OECD Nuclear Energy Agency (NEA) Working Group on Risk Assessment (WGRISK) periodically publishes a status report on the use and development of Probabilistic Safety Assessment (PSA) in its member countries. The most recent update, approved by the Committee on the Safety of Nuclear Installations (CSNI) and expected to be published in 2027, provides a snapshot of international PSA practices drawing on contributions from more than twenty regulatory authorities and technical safety organisations.

This paper presents an overview of the report with a particular focus on the treatment of safety goals, numerical safety criteria and risk metrics adopted in different national frameworks. The report demonstrates that PSA plays an integral role in safety assessment, licensing and regulatory decision making across a wide range of countries. While some regulators specify explicit numerical criteria for core and/or fuel damage frequency, large or large early radioactive release frequency, or individual and societal risk, others employ qualitative goals supported by numerical targets used as decision aids rather than regulatory limits.

The paper highlights key similarities and differences in the definition and application of risk metrics at PSA Levels 1, 2 and 3. Recent developments in emerging challenges associated with extending safety goals beyond single unit assessments, including risk aggregation for multi-unit and multi-source sites, treatment of spent fuel pools and the increasing use of consequence based metrics are identified and discussed.

The findings illustrate a general trend towards broader PSA scope, increased use of international guidance, and greater reliance on risk informed decision making, while also identifying areas where different countries adopt different approaches.