1979 Tennessee top-secret nuclear fuel plant accident

The location
A unidentified top-secret nuclear fuel plant in Tennessee.

1979 accident
A unquantified amount of highly enriched uranium spewed out of a top-secret nuclear fuel plant in Tennessee. This lead to 1,000 people getting up to 500% as much radiation as they would normally have had in a year.

Link
http://www.cbsnews.com/htdocs/nuclear_disasters/framesource_timeline.html