Abstract: With the increasing saturation of coastal nuclear power plant sites, it is a new idea to select islands as nuclear power plant sites. In view of the problem that the island sites are vulnerable to typhoon disasters, the design basis flood level of the sites is determined by studying astronomical high tide, sea level rise, possible maximum storm surge and maximum typhoon wave. The results show that the astronomical high tide level of 10% superfrequency in this region is 3.14 m and the predicted sea level rise in the next 80 years will be 0.31 m. Based on MIKE21 model, a variety of hypothetical typhoon paths were constructed using tropical cyclone parameters. The northwest moving path of typhoon with 0.5R (R is the maximum wind speed radius of typhoon) to the left of the site produces the possible maximum storm surge, with the maximum water level of 2.99 m. When the typhoon moves in the direction of west, with R to left of the site, the maximum H_1/100 wave height reaches 8.02 m, especially on the east side of the island, which suffers from severe typhoon wave threats. Considering the superposition of various basis flood factors, the design basis flood level of the island nuclear power plant site reaches 11.25 m. Because the proposed site is located on an island and surrounded by sea waters, compared with other coastal sites, the storm surge level is relatively small, but the impact of waves is more significant.

Key words: island nuclear power plant, design basis flood level, possible maximum storm surge, typhoon wave height