Japan 's electric power companies run 54 nuclear reactors at 17 power plants . The Fukushima Daiichi plant is the most dangerous, and it was built in a tsunami zone that has been prone to earthquakes for decades. Most Japanese plants -- including the three facing emergencies -- use boiling-water reactors .
Japan 's electric power companies run 54 nuclear reactors at 17 power plants . They produced more than 280,000 gigawatt-hours of electricity in 2010 . Most Japanese plants -- including the three facing emergencies -- use boiling-water reactors .