On April 26, 1986, a disaster struck at the Chernobyl nuclear power plant in Ukraine. Due to human error during a safety test, reactor number four exploded, releasing massive amounts of radiation into the atmosphere. Over 100,000 people had to be evacuated from the area surrounding Chernobyl. The explosion was equivalent to 400 Hiroshima bombs and exposed around 600,000 recovery workers called "liquidators" to high levels of radiation during the decontamination process. Decades later, Chernobyl remains a highly contaminated site that is hazardous to human life.