National Museum of Nuclear Science & History
Harold Hoover was a member of the Special Engineer Detachment during the Manhattan Project. He worked as a filter foreman at the Y-12 Plant, but his real job was in counterintelligence, to ensure no sabotage occurred.
August “Gus” Knuth was a millwright and carpenter who helped construct Chicago Pile-1. He was present on December 2, 1942 when the pile went critical in the first self-sustaining chain reaction in history.
Fredric Stokes was a staff worker at Los Alamos during the Manhattan Project.