The Chernobyl nuclear accident occurred in 1986 at the Chernobyl Nuclear Power Plant in Ukraine. An explosion during a safety test destroyed Reactor 4 and released large amounts of radiation into the atmosphere. Over 30 people died immediately from radiation exposure. Around 200,000 people were relocated long term due to radiation contamination of a 150,000 square kilometer area. Long term effects of radiation included increased cases of cancer and thyroid disease. The landscape and food/water supply of the affected regions also became contaminated.