Rocky Flats Environmental Technology Site

Rocky Flats began production in April 1952 – just one year after the Atomic Energy Commission selected the site 16 miles northwest of downtown Denver. From 1952 to 1989, the primary mission of Rocky Flats was the processing and machining of plutonium and other materials into detonators, also called “triggers,” for nuclear weapons.

http://www.bwxt.com/operations/rfets.html