The Onagawa Nuclear Power Plant, a 3-unit BWR site typical of Japan's nuclear plants.
Since 1973, nuclear energy has been a national strategic priority in Japan, as the nation is heavily dependent on imported fuel, with fuel imports accounting for 61% of energy production. There has been concern about the ability of Japan's nuclear plants to withstand seismic activity. The Kashiwazaki-Kariwa Nuclear Power Plant was completely shut down for 21 months following an earthquake in 2007.
Following an earthquake, tsunami, and the failure of cooling systems at the Fukushima I Nuclear Power Plant on March 11, 2011, a nuclear emergency was declared. This was the first time a nuclear emergency had been declared in Japan, and 140,000 residents within 20 km of the plant were evacuated. The amount of radiation released is unclear, and the crisis is still ongoing.