Every industry or energy sector is subject to accidents. The nuclear energy industry is no exception, but serious accidents have been very scarce. Globally, the nuclear reactors as a whole have been operating in excess of 15,000 reactor-years and during this period there have been only three serious accidents and only one had human causalities. Namely, the following accidents: the American nuclear power plant Three Mile Island (1979), the Ukrainian Chernobyl (1986), and the Japanese Fukushima Daiichi (2011).