On 26 April 1986, reactor number 4 at the Chernobyl Nuclear Power Plant exploded. Theaccident released at least 100 times more radiation than the bombs dropped on Nagasaki andHiroshima in Japan, and is considered to be the worst nuclear accident in the history ofhumanity. It is classified as a level 7 incident, the highest level on the International NuclearEvent Scale. The only other incident to be categorized at this level is the Fukushima Daiichinuclear disaster of 2011.In the days, months and years that followed, over half a million civilians and military person(“liquidators”) were involved in the decontamination process to avert a potential secondcatastrophe.