Successive safety improvements for nuclear power plants (NPPs) have been required by society as well as by regulatory agencies because of the nuclear accident at the Fukushima Daiichi Nuclear Power Plant due to the Great East Japan Earthquake and Tsunami. The establishment of a methodology for the fragility evaluation of seawalls is essential for developing a probabilistic risk assessment (PRA) for tsunamis that is applicable to NPPs where the hazard level of tsunamis is high.
In the present study, fragility evaluation methods of reinforced concrete (RC) seawalls are documented. Two main damage modes of the seawall, namely overflow and physical damage caused by tsunami wave pressure, were the primary focus. Using the documented fragility evaluation methodology, a conceptual study for evaluating the fragility of a RC seawall against overflow and the impact of tsunami wave pressure is performed, and fragility curves are obtained by considering the following uncertainties: evaluation accuracy of the inundation level and tsunami wave pressure, density of the seawater, compressive strength of concrete, yield strength of reinforcement, and evaluation accuracy of the shear capacity.