On April 26, 1986, a nuclear accident occurred at the Chernobyl nuclear power plant in Ukraine. Operator errors caused Reactor 4 to explode, releasing 190 tons of radioactive material into the atmosphere. The explosion started a fire that lasted 10 days and spread radiation over large areas. Over 30 people died within months from radiation poisoning, and thousands more developed long-term health issues like cancer from exposure to the radiation released in the accident. The Chernobyl disaster demonstrated the need for improved safety procedures and protocols at nuclear power plants to prevent such accidents from occurring again.