The Manhattan Project: Making the Atomic Bomb
Part IV: The Manhattan Engineer District in Operation
Progress at Oak Ridge
During winter 1944-45 there was substantial progress at Oak Ridge, thanks to improved performance in each of the production facilities and Nichols's work in coordinating a complicated feed schedule that maximized output of enriched uranium by utilizing the electromagnetic, thermal diffusion, and gaseous diffusion processes in tandem. Nine Alpha and three Beta racetracks were operational and, while not producing up to design potential, were becoming significantly more reliable because of maintenance improvements and chemical refinements introduced by Tennessee Eastman. The S-50 thermal diffusion plant being built by the H. K. Ferguson Company was almost complete and was producing small amounts of enriched material in the finished racks, and the K-25 gaseous diffusion plant, complete with barriers, was undergoing formal leak tests. By March 1945, Union Carbide had worked out most of the kinks in K-25 and had started recycling uranium hexafluoride through the system. S-50 was finished at the same time that the Y-12 racetracks were demonstrating increased efficiency. The Beta calutrons at the electromagnetic plant were producing weapon-grade uranium-235 using feed from the modified Alpha racetracks and the small output from the gaseous diffusion and thermal diffusion facilities. Oak Ridge was now sending enough enriched uranium-235 to Los Alamos to meet experimental needs. To increase production, Groves proposed an additional gaseous diffusion plant (K-27) for low-level enrichment and a fourth Beta track for high-level enrichment, both to be completed by February 1946, in time to contribute to the war against Japan, which many thought would not conclude before summer 1946.