Bud Uanna gives his background for his Foreign Service Essay 1956. Note 1941 - 1947. Before the Manhattan Project he was involved in Radar, one of the most secret and effective weapons of World War II. Uanna makes it clear that his security responsibilities on the Manhattan Project went along with his engineering input in the Atomic Bomb's production  "...design and assembly of atomic bombs, ...and usual security responsibilities."
William Uanna 1956
U.S. Department of State William Uanna 1956