25 October 1950
(U.S. Air Force, Washington, D.C.)
Source: NICAP.org (nicap.org/reports/501012oakridge_rep.htm)
The document comes from the Project Blue Book files.
http://www.nicap.org/docs/501012oakridge_docs.pdf
(wikimedia.org image)
“Y-12” Area at Oak Ridge, Tennessee
(nicap.org photo)
(nicap.org photo)