The Chernobyl accident in 1986 was the result of a flawed reactor design that was operated with inadequately trained personnel.
Chernobyl: Facts about the world’s worst nuclear disaster
The Chernobyl accident in 1986 was the result of a flawed reactor design that was operated with inadequately trained personnel. The resulting steam explosion and fires released at least 5% of the radioactive reactor core into the environment, with the deposition of radioactive materials in many parts of Europe.