What Happened at Chernobyl: 40 years on - BBC World Service Documentaries

Inside Chornobyl, 40 years after the world's worst nuclear disaster

40 years ago today, on April 26, 1986, the Chernobyl disaster began during a late night safety test at Reactor No. 4. A combination of design flaws in the RBMK reactor and human mistakes caused a sudden power surge. At 1:23 a.m., explosions blew the reactor apart, exposing its core and releasing massive amounts of radioactive material into the atmosphere. Firefighters and plant workers were the first to respond, not fully aware of the radiation danger. Many walked directly on radioactive debris

Going inside the Chernobyl nuclear power plant, 40 years on from the disaster. #BBCNews

AP sees inside Chernobyl Nuclear Power Plant 40 years after disaster

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