Naoto Kan said three reactors at Hamaoka plant should be suspended until new safety measures were put in place.
Experts said the chances of a powerful quake hitting the area were high.
Engineers are still working to stabilise the Fukushima Daiichi nuclear plant, which was hit by the devastating earthquake and tsunami on 11 March.
I think the reason for suspecting that an earthquake will strike is mainly based on the fact, that Japan sits on top of what is referred to as the "Pacific ring of fire." Anywhere in that region which includes San Fransisco and L.A. is more prone to earthquakes.
History has shown Japan has had numerous large eathquakes. Scientists are sure more are coming, the real problem lies in the when and where. Indonesia at the moment are also building a nuclear power plant in an area that is well known for it's earthquake activity.
I'm trying to find the link but Japan was considering another nuclear power plant on the ocean just oppisite a volcano that recently erupted. Not sure if they have changed those plans yet. It's good to see that they are re-thinking everything though.
News on the recent disaster has dried up. They are still struggling, according to the International Atomic Energy Agency.
I think it is now listed alongside Chernobyl in seriousness.
I don't know anything about the other reactors at other plants, or how they calculate new chances of quakes, but I've been wondering about how things were going at the ones already in danger, such as the one mentioned. Not much real news lately about it. But new safety measures should be top priority at any nuclear plant I would think. Hope every one of them everywhere are checking into that.