The worst nuclear disaster in history took place during what should have been a routine safety check at Chernobyl nuclear plant.

Negligence resulted in a chain reaction of explosions that melted the fourth nuclear reactor.

The aftermath sent a devastating cloud of radioactive contaminants being sent into the atmosphere, but Moscow was not initially forthcoming about what had happened.

This was President Reagan's response to reporters' initial questions. Report by Guinnesse. Like us on Facebook at http://www.facebook.com/itn and follow us on Twitter at http://twitter.com/itn