In the three years since the Fukushima disaster, Japan's utilities have pledged $15 billion to harden their nuclear plants against earthquakes, tsunamis, tornadoes and terrorist attacks.
But as the nuclear safety regulator prepares to rule on whether the first of the country's 48 idled reactors is ready to come back online, the post-Fukushima debate about how safe is safe enough has turned to a final risk: volcanoes.
The Nuclear Regulation Authority has already said the chance of volcanic activity during the life span of Kyushu Electric Power Co.'s nuclear plant at Sendai, Kagoshima Prefecture, is negligible, suggesting it will give it the green light. The plant lies in a region of active volcanic sites.Critics, including some scientists who were consulted by the NRA, say that shows regulators are turning a blind eye to the kind of unlikely but potentially devastating chain of events that pushed the Fukushima No. 1 plant into a triple meltdown in 2011, when a tsunami crashed into the facility.