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 plants. 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.