The deadly volcanic eruption of Mount Ontake over the weekend may strengthen the argument of activists campaigning to keep the country's 48 reactors shut.
Japan's atomic plants are offline for safety checks as a result of the earthquake and tsunami that caused the meltdown of three reactors in Fukushima more than three years ago.
The Nuclear Regulation Authority has said two reactors at a plant run by Kyushu Electric Power Co. meet new safety standards, indicating they are closest to restarting.