Chernobyl
However, Lars-Olov Höglund, who was responsible for the nuclear plant Forsmark for many years, said the incident was the most dangerous one since 
 and Three Mile island, and that a meltdown was avoided only by pure luck. His views have however been questioned as he is involved in litigation with the Swedish nuclear industry and is known as an outspoken nuclear critic. Researchers at the Royal Institute of Technology as well as the personnel at the power plant were critical of Höglunds' view.
Swedish nuclear reactors shut down over safety concerns