These include the Chernobyl disaster (1986), the Three Mile Island accident (1979), and the Fukushima Daiichi nuclear disaster (2011). However, when compared to other forms of energy nuclear is surprisingly safe - the plants are built to be very robust and safe, and the aforementioned occurences are the only three to happen in the history of civil nuclear power (over 14,500 cumulative reactor-years of commercial operation in 32 countries).