The IAEA General Safety Requirements (GSR Part 4) emphasize the role of probabilistic methods in safety assessment for all nuclear facilities. While Probabilistic Safety Assessment (PSA) is well established for nuclear power plants and research reactors, its application to non-reactor facilities remains less standardized and presents specific methodological challenges.
This paper presents the application of PSA to the European Spallation Source (ESS), a high power accelerator driven neutron source, as an example of a complex non-reactor nuclear installation. The study demonstrates how traditional PSA elements, including hazard identification, initiating event and scenario analysis, likelihood estimation, and consequence assessment, can be adapted using a graded approach to reflect the characteristics of non-reactor facilities.
Compared to reactor PSAs, key differences include a broader distribution of hazardous materials, diverse operational configurations, and distinct initiating event sets. Additionally, traditional reactor risk metrics may not be directly applicable, especially for facilities located closer to the public, where consequence-based metrics such as release magnitude and off-site dose are more appropriate. Further challenges include limited reliability and initiating event data.
The ESS case study shows that, despite these differences, PSA provides valuable insights for identifying dominant risk contributors, supporting design optimization, and strengthening risk-informed decision-making for non-reactor nuclear facilities.