The Chernobyl nuclear disaster occurred on April 26, 1986 at the Chernobyl Nuclear Power Plant in Ukraine. There was a massive power surge and explosion in reactor number 4, releasing large amounts of radioactive particles into the atmosphere. Over 100,000 people had to be evacuated and many suffered from radiation sickness in the aftermath. The disaster highlighted issues with the design of the Soviet nuclear reactors and caused widespread environmental contamination.