Nuclear energy

Nuclear power

Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

 was a national strategic priority in Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, but there has been concern about the ability of Japan's nuclear plants to withstand seismic activity. The Kashiwazaki-Kariwa Nuclear Power Plant

Kashiwazaki-Kariwa Nuclear Power Plant

The is a large, modern nuclear power plant on a 4.2-square-kilometer site including land in the towns of Kashiwazaki and Kariwa in Niigata Prefecture, Japan on the coast of the Sea of Japan, from where it gets cooling water...

 was completely shut down for 21 months following an earthquake in 2007.

Following an earthquake, tsunami

2011 Tōhoku earthquake and tsunami

The 2011 earthquake off the Pacific coast of Tohoku, also known as the 2011 Tohoku earthquake, or the Great East Japan Earthquake, was a magnitude 9.0 undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST on Friday, 11 March 2011, with the epicenter approximately east...

, 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.