The worst nuclear power accident in history took place in Chernobyl in 1986 when a reactor there exploded, killing tens of people instantly and exposing hundreds of thousands more to radiation.

The lack of a containment structure for the Chernobyl reactor, whichmight have limited the emission of radioactivity into the atmosphere after theexplosion, is only the most glaring example.

After reactor no. 4 exploded at Chernobyl in 1986 due to errors in both design and operation it sent plumes of radioactive dust as far away as Japan and the U.S..