The importance and significant benefits of probabilistic safety assessment (PSA) methodologies used in the evaluation of risk and the enhancement of safety for nuclear power plants were among the key topics discussed at the recently held International Symposium on PSA for reactors of singular designs.
The International Symposium on PSA for reactors of singular designs, for example First of a Kind (FOAK) Reactors, SMRs, and Generation IV Reactors, was hosted by the Office for Nuclear Regulation (ONR) in Liverpool, United Kingdom, from 7 to 9 June 2022, and was jointly organised by the IAEA and the OECD Nuclear Energy Agency (NEA). Participants came together to share knowledge and national experiences in PSA for reactors of singular designs.
"Understanding more about the challenges related to developing and assessing the PSA for these unique reactors is vital, as regulatory assessment of small modular reactors (SMRs) and advanced modular reactors (AMRs) is expected to be a key part of our work in the future," said Josh Gordon, an ONR inspector and Deputy Professional Lead responsible for PSA.
PSA is a systematic and comprehensive approach to the evaluation of risks of complex technological infrastructures, such as nuclear power plants. The objective of such assessments is to ensure and demonstrate the safety of such facilities, including the reactors of a singular design.
"PSA plays a key role in the continuous safety improvement at nuclear power plants as it entails an integrated and in-depth safety assessment to ensure that accident sequences leading to large or early radioactive releases are practically eliminated," said Shahen Poghosyan, an IAEA nuclear safety officer. "This assessment is equally important to undertake for reactors of singular designs."
The symposium provided a platform for information exchange and deep technical discussions among subject matter experts. Interactions focused on ways of applying and conducting PSA for reactors of singular designs, including specific assessments on key elements such as analytical tasks focusing on initiating events, accident sequence, human reliability, and data analysis. In particular, the deliberations covered the differences and challenges of PSA for these specific types of reactors, lessons learned and recommendations for the development of PSAs, and the use of risk-informed decision-making processes for reactors of singular designs.
The symposium provided a better understanding of the challenges and of what is available worldwide in terms of PSA for these reactors. It also resulted in suggestions on how to resolve those challenges, for example moving from the 'core damage' risk metric to metrics based on the 'radiological consequences of the accidents'," said Poghosyan.
"This was an excellent opportunity to exchange information and to discuss ideas with knowledgeable people. It gave confidence to the participants in the useful application of PSAs in evaluating the safety level of reactors with singular designs," said Mirela Nitoi, the Coordinator of the International Cooperation R&D Program in the Institute for Nuclear Research (RATEN ICN). "International collaboration could be a key element for reaching harmonization of the approaches, as we solve challenges related to the performance of PSA for particular reactors."
The IAEA facilitates information sharing on safety analysis techniques for innovative reactors. This topic is also being covered in the upcoming International Conference on Topical Issues in Nuclear Installation Safety: Strengthening Safety of Evolutionary and Innovative Reactor Designs, taking place at the IAEA headquarters in Vienna from 18 to 21 October 2022. Registration for the conference is open here.
