RISMET Project - Benchmark Study of Risk-Informed In-Service Inspection Methodologies

This paper describes the main results of the RISMET benchmark project, whose final report was recently published by the OCDE/NEA. The RISMET project was started in 2005 by the Joint Research Centre (JRC) of the European Commission (EC) together with the Nuclear Energy Agency (NEA), with the goal of benchmarking several risk-informed in-service inspection (RI-ISI) methodologies. More than twenty organizations from Europe, U.S., Canada and Japan participated, representing utilities, regulators and research organizations. In the project several RI-ISI methodologies were applied to the same case, consisting of four selected piping systems in Unit 4 of the Ringhals nuclear power plant (PWR) in Sweden. The different RI-ISI methodologies were compared with each other and to the deterministic ASME XI ISI selection procedure. The scope of the benchmark was limited to four systems, but the variety regarding safety class, potential degradation mechanisms and pipe break consequences ensured a good coverage of issues for a comparative study. The risk-informed methodologies showed some significant differences and resulted in slightly different risk ranking and selection of inspection sites. However, the results of the benchmark indicated that the risk impact of these differences is small, and the RI-ISI approaches identify safety important piping segments that are ignored by approaches not using probabilistic safety assessment (PSA). The results of the benchmark exercise RISMET improve the knowledge on differences in approaches and their impact on plant safety and promote the use of risk-informed ISI.

GANDOSSI Luca;  MARTIN Oliver;  HUERTA A.; 

2012-03-30

International Association for Structural Mechanics in Reactor Technology (IASMiRT)

JRC65406