A large explosion exposed vast amounts of radioactive materials to the open air, releasing a radioactive cloud that floated over eastern and northern Europe for months. In the ensuing confusion, Soviet authorities hesitated to enforce appropriate evacuation and crisis management procedures, and hundreds of thousands of residents and firefighters were needlessly exposed to high radiation.
Today, the area around Chernobyl is a wildlife preserve (no joke--see photo at bottom right). Radiation levels around Reactor 4--the site of the disaster--remain elevated to over 1m times those in our cities. The nearby villages have been evacuated for the most part, but other reactors at Chernobyl continued to run until 2000. For reference, 2000-1986 = 14 years after the accident in which operators were paid to continue to produce nuclear energy at its incredibly radioactive epicenter.
See here for a lengthier account of the accident and its aftermath.
