- Net Capacity: 4,268 megawatts
- Location: Fukushima, Japan
- Number of Reactors: 4
- Output (2010): 29,168.108 gigawatt-hours
Nuclear energy has been a national priority in Japan since 1973, when the oil crisis exposed a disturbing vulnerability; until then, Japan depended heavily on imported oil to meet its primary energy needs. By 2010, some 50 reactors supplied the country with 30 percent of its electricity [source: World Nuclear Association]. However, although all Japanese reactors were constructed with extensive safety mechanisms to withstand the country's frequent earthquakes, the magnitude 9.0 earthquake and massive tsunami that struck offshore of the city of Sendai on March 11, 2011, caused significant problems for Japan's nuclear power program. Eleven reactors at four different nuclear power plants shut down automatically when the quake hit, but the tsunami caused a nuclear accident at Fukushima Daiichi after a power loss disrupted its reactor cooling units. The reactor cores of Units 1, 2 and 3 partially melted in the first three days of the disaster [source: World Nuclear Association].
Before the disaster, Fukushima Daiichi had a net capacity of 4,546 megawatts, making it the second biggest power station in Japan. Now that four of the plant's six reactors are permanently shut down, neighboring Fukushima Daini, which generates 10 percent of the 279,229.53 gigawatt-hours of Japan's annual nuclear power production, gains a spot on our top 10 list [source: IAEA PRIS].
It may take some time to get Fukushima Daini's reactors back online, however. The cooling function in Units 1,2 and 4 were lost after the tsunami. As a result, each one underwent a cold shutdown, which means the reactor coolant temperatures were successfully brought to below 212 degrees F (100 degrees C). The facility suffered minor damage in the disaster, but as of November 2011, Fukushima Daini was deemed to be safe and secure. The reactors will need to undergo a series of stress tests before they are back online [source: Tokyo Electric Power Company].
A Japanese facility claims the next spot on our list, too.