According to a survey by the Mainichi Shimbun newspaper, a number of Japan’s nuclear power plants are at risk if a large-scale volcanic eruption occurs. The survey questionnaire was given to volcanologists nationwide, and from the data that returned, it turns out that the Sendai Nuclear Power Plant in Kagoshima Prefecture and the Tomari Nuclear Power Plant in Hokkaido may be facing the highest risk among the 17 nuclear power facilities mentioned in the survey.
The questionnaire was mailed to 134 university professors and associate professors (not including specially appointed educators) who were doing work in the field of volcanology, and from that total, 50 responded. This is the first recorded survey connecting volcanic risks to nuclear power plants, with all the data gleaned from experts in the field. The surveyed volcanologists were asked from their expertise and knowledge to specify which of the nuclear power plants were at risk from a possible major eruption from the country’s active volcanoes, taking into consideration a nuclear facility’s maximum 60-year operating life. The Sendai nuclear facility received the highest number of responses at 29, followed by the Tomari plant at 25.
The volcanologists pointed out that the Sendai plant is at risk from numerous surrounding volcanic areas known as calderas – enormous depressions in the earth created by huge volcanic eruptions – like the Aso caldera in Kumamoto Prefecture and the Aira caldera in Kagoshima Prefecture. The Tomari plant, as well as the Higashidori Nuclear Power Plant in Aomori Prefecture and the Genkai Nuclear Power Plant in Saga Prefecture, were pointed out as being in the vicinity of calderas. But the respondents also pointed out that the possibility of this happening is extremely low, and even then, it is still very difficult to predict when volcanic eruptions might occur.