Oak Ridge K-25 Gaseous Diffusion plant

This one plant absorbed 25 percent of the Manhattan Project's wartime funding.

the world's first gaseous diffusion plant, the method of uranium enrichment with the best theoretical basis, championed by the British, but which had never been tried in practice.

K-25 was huge, even by Oak Ridge standards, with fifty four-story buildings totaling 2,000,000 square feet, in a U-shape measuring a 2,600 feet long by 1,000 feet wide. Covering some 44 acres, the K-25 building was the world's largest roofed structure when it was completed in March 1945. Housing and service facilities were built for the population that eventually reached 15,000.

Y-12Inside K-25, a series of over 1,000 huge cells were linked in a cascade through which uranium hexafluoride gas traveled, with small fractions of the U-235 isotope separated by a barrier material with microscopic pores. Production problems at K-25 led to an August 1943 decision that K-25 would not fully enrich uranium but would produce partially enriched feeder material for Y-12. A key production problem was developing a suitable diffusion barrier, material with millions of tiny holes that would also withstand the extremely corrosive gas involved. That problem was not solved until 1944 enabling production in 1945.