In the early hours of 26 April 1986, reactor No. 4 at the Chernobyl nuclear power plant near Pripyat, in what was then the Ukrainian SSR, was destroyed during a safety test that had been run with several protection systems disabled. A sudden power surge led to a steam explosion, a second explosion and a graphite fire that burned for days, releasing radioactive material across large parts of Europe.
Two plant workers died on the night of the accident, and 28 emergency workers and staff died of acute radiation syndrome in the following months. The wider long-term death toll is disputed, with estimates ranging from around 4,000 to considerably higher. Roughly 350,000 people were eventually resettled from the exclusion zone around the plant.
This episode traces the design flaws of the RBMK reactor, the decisions made in the control room, the delayed evacuation of Pripyat, and how the accident changed nuclear safety culture worldwide.
