Risk assessments are used to determine the probability of harmful events at a nuclear plant. They are valuable for determining the relative benefit and better selection of safety enhancements.
The safety of a nuclear facility is based on ensuring that it is designed to withstand a range of abnormal conditions, including failures of systems or components, internal events such as fires and external events such as earthquakes or severe weather. In the 1980s, probabilistic risk assessments (PRAs or probabilistic safety assessments – PSAs) were introduced to assess the relative risk posed by a failure or event. With a PRA, the safety of a nuclear facility can be systematically assessed, taking into account actual operating experience with system and component reliability, to identify and mitigate potential vulnerabilities.
Since their introduction, NEA co-operation on PRAs has been led by the Committee on the Safety of Nuclear Installations (CSNI), most recently under the Working Group on Risk Assessment (WGRISK). The working group members share experience with the use of PRAs, including good practises and new applications. WGRISK produces technical opinion papers summarising expert views on specific applications of PRA such as assessing the risks associated with seismic and fire events. The group also assesses research into new developments such as the use of PRA for digital systems or the determination of human reliability for use in PRA.
The Working Group supports improved uses of Probabilistic Safety Assessment (PSA) in risk-informed regulation and safety management through the analysis of results and the development of perspectives regarding potentially important risk contributors and associated risk-reduction strategies. The Working Group addresses PSA methods, tools, and data needed to provide this information.