The idea of a benchmark study on risk-informed in-service inspection (RI-ISI) was initially developed within a subgroup of the ENIQ Task Group on Risk. The preliminary JRC project proposal was endorsed by the NEA’s Committee on the Safety of Nuclear Installations (CSNI) Working Group on Integrity and Ageing of Components and Structures (WGIAGE), which resulted in approval by the CSNI in December 2005. The Benchmark Study on Risk-Informed In-Service Inspection Methodologies (RISMET) project eventually kicked off at Leibstadt NPP (Switzerland) in January 2006 with the objective to apply various RI-ISI methodologies to the same case (namely, selected piping systems in one nuclear power plant). The comparative study was aimed at identifying the impact of such methodologies on reactor safety and how the main differences influence the final result (i.e. the definition of the risk-informed inspection programme).
This report documents the main results and conclusions of the RISMET project which constitutes a unique comparative study of selected approaches used to set up an ISI programme. As a result, the knowledge of different approaches and their impact on plant safety is likely to be enhanced and at the same time, the use of risk-informed ISI will be promoted.