What is Nuclear accident?
A '''nuclear accident''' is an accident that releases [[Radioactive decay|radioactivity]] to the environment, harmfully affects people, and causes a [[nuclear meltdown]].<ref>{{Cite web|last=Staff|first=IAEA|title=International Nuclear and Radiological Events Scale Users' Manual, 2008 Edition|url=http://www-pub.iaea.org/MTCD/publications/PDF/INES-2009_web.pdf|url-status=dead|archive-url=https://web.archive.org/web/20110515164252/http://www-pub.iaea.org/MTCD/publications/PDF/INES-2009_web.pdf|archive-date=May 15, 2011|access-date=July 16, 2010|publisher=International Atomic Energy Agency|location=Vienna, Austria|page=183}}</ref> The most serious nuclear accident has been the [[Chernobyl disaster]] in 1986. Other serious nuclear accidents include [[Fukushima Daiichi Nuclear Power Plant]] accident, [[Three Mile Island accident]], the [[Windscale fire]], [[Mayak accident]], and the SL-1 accident. In the period to 2007, 63 major nuclear accidents have occurred at [[nuclear power plant]]s. Twenty-nine of these have occurred since the Chernobyl disaster, and 71 percent of all nuclear accidents (45 out of 63) occurred in the United States.<ref>Benjamin K. Sovacool. The Costs of Failing Infrastructure ''Energybiz'', September/October 2008, pp. 32-33.</ref><ref>[[Benjamin K. Sovacool]]. The costs of failure: A preliminary assessment of major energy accidents, 1907–2007, ''[[Energy Policy]]'' 36 (2008), pp. 1802-1820.</ref> [[File:Hydrogen explosion Fukushima Unit 1 cg visualization.png|thumb|390px|Fukushima I Unit 1 [[nuclear reactor]] before and after the [[hydrogen]] explosion.]] ==Fukushima, Onagawa and Tōkai== On 11 March 2011, the Magnitude 9.0 devastating [[2011 Sendai earthquake and tsunami|Sendai earthquake]] and [[tsunami]] took place in [[Japan]]. As a result, ''[[Fukushima Daiichi Nuclear Power Plant]]'', ''Fukushima Daini Nuclear Power Plant'', ''Onagawa Nuclear Power Plant'' and ''Tōkai Nuclear Power Plant stations'' consisting of eleven (11) reactors were automatically shut down following the earthquake.<