The Nuclear Regulation Authority will reassess the safety risks posed by possible natural disasters to certain nuclear power plants that have been declared to be fit for operation under the new safety standards. The nuclear watchdog’s unusual decision has been prompted by recent discoveries of new facts concerning possible effects of volcanic eruptions on the Mihama, Oi and Takahama nuclear power plants operated in Fukui Prefecture by Kansai Electric Power Co. It is a totally reasonable decision based on the principle of putting the top priority on safety in regulating nuclear plants. Initially, Kansai Electric asserted that volcanic ash posed no threat to the safety of the three nuclear plants. Its claim was based on its own estimate of the amount of volcanic ash that would fall on the plants. Using research findings and geological surveys as well as simulations of eruptions of Mount Daisen, a volcanic mountain in Tottori Prefecture located about 200 kilometers from the plants, the Osaka-based utility estimated that the nuclear compounds could be coated with up to 10 centimeters of ash from a major volcanic eruption.
Asahi Shimbun 27th Nov 2018 read more »