Existing design approaches to nuclear power plants subject to tsunamis: A critical review

The 2011 Fukushima Daiichi nuclear accident in Japan highlighted the potential vulnerability of nuclear power plants (NPPs) to tsunami events. In order to ensure the operational continuity in the aftermath of such events, designers of NPP structures need to be able to quantify tsunami inundation and associated loading with reasonable accuracy. This paper seeks to explore and critically review the prevalent codified guidance that exists for NPP structures subject to tsunamis. Firstly, the process of tsunami-resilient design is briefly outlined in line with the nuclear regulations in Japan. Secondly, the existing formulae used to evaluate hydrodynamic loads and debris impact force for the tsunami-resilient design of land-based structures on the nuclear site are discussed. Thirdly, the differences between the Japanese and US tsunami-resilient design codes, JEAC 4629 and ASCE/SEI 7 respectively, are distinguished and discussed. The former is specific to nuclear facilities licensed by the Japanese Nuclear Regulatory Authority (NRA), whilst the latter is aimed at general buildings which could include nuclear power stations controlled by the US Nuclear Regulatory Commission (NRC). Key aspects which have not been fully covered by these codes are then highlighted to identify future research directions. A number of gaps and inconsistencies exist between the widely accepted design standards.