Comparative application of digital I&C modeling approaches for PSA

Newly built and modernized older nuclear power plants are equipped with digital I&C systems. However, currently there is no specific guidance internationally agreed for modeling of digital I&C systems in PSA. Thus, the OECD Nuclear Energy Agency (NEA) Committee on the Safety of Nuclear Installations (CSNI) Working Group on Risk Assessment (WGRISK) initiated a task called “Digital I&C PSA – Comparative application of DIGital I&C Modeling Approaches for PSA” (DIGMAP) in July 2017. The objective of the task is to compare different modeling approaches and identify possible methods and issues for further development. A simplified boiling water reactor design equipped with digital features is used as a common reference plant for the task. Each participating country develops its own PSA model based on the plant description. Through comparison, different approaches to account for e.g. software reliability, fault-tolerant techniques, and network communication in the PSA will be explored. Nine countries are currently participating in the task. The planned duration for the task is 2017-2020. This paper describes the efforts done so far and presents preliminary results and insights.