The Manhattan Project: Making the Atomic Bomb
Part VI: The Manhattan District in Peacetime
From the time S-1 became public knowledge until the Atomic Energy Commission succeeded it on January 1, 1947, the Manhattan Engineer District controlled the nation's nuclear program. Groves remained in command, intent upon protecting America's lead in nuclear weapons by completing and consolidating the organization he had presided over for three years in challenging wartime conditions. He soon found that peacetime held its own challenges.
According to a plan approved by Stimson and Marshall in late August 1945, Groves shut down the thermal diffusion plant in the K-25 area on September 9 and put the Alpha tracks at Y-12 on standby during September as well. The improved K-25 gaseous diffusion plant now provided feed directly to the Beta units. Hanford's three piles continued in operation, but one of the two chemical separation areas was closed. Los Alamos was assigned the task of producing a stockpile of atomic weapons. Actual weapon assembly was to be done at Sandia Base in Albuquerque, where engineering and technical personnel were relocated with the staff previously stationed at Wendover Field in western Utah.