Development of Probabilistic Methodology for Evaluating Tsunami Risk on Nuclear Power Plants

Since nuclear power plants in Japan are located on the seashore, it is also required to ensure sufficient safety against tsunamis and high tidal waves. The Examination Guide for Seismic Design of Nuclear Power Reactor Facilities revised by the Nuclear Safety Commission in 2006 refers to safety consideration of tsunamis and landslide of slopes around site as accompanying phenomena of earthquake as well as residual risks of earthquakes. JNES has been developing the methods for probabilistic safety assessment for tsunami events (tsunami PSA), in order to quantitatively evaluate the safety level of nuclear power plants against tsunamis. The tsunami PSA consists of 4 components, schematic analyses of accident scenario, tsunami hazard evaluation, tsunami fragility evaluation and accident sequential analysis. In this paper, outline of tsunami PSA and tsunami hazard and fragility evaluation applying numerical tsunami simulation are described.