Wednesday, August 31, 2011
The K-25 building was built to separate uranium's fissile isotope, uranium-235, from its other, non-fissile, isotopes, using the gaseous diffusion process. Uranium-235 occurs naturally, but it accounts for only about 0.7% of naturally-occurring uranium. It must be enriched to 20% or more for use in a nuclear reactor, and much more for nuclear weapons. The gaseous-diffusion process is a brute-strength approach that exploits the minute differences in the size of uranium isotopes by pushing gaseous uranium hexafluoride gas through thousands of membranes, called barriers, until the desired enrichment is reached.
The whole process requires thousands of pumps and electric motors, and large amounts of electricity. I've read that during the war, the K-25 plant alone used more electricity than the city of Boston at the time. Hence, it was the building of Norris Dam that allowed the Manhattan Project to be sited in east Tennessee. It took a very large building to contain all of that equipment. The finished, U-shaped building was a mile from one end of the "U" to the other, and contained some 2 million square feet under roof. Workers rode bicycles around the top floor to get from one end to the other.The photo below gives a sense of scale:
There has been considerable concern for historic preservation, but such presents enormous challenges. The scale, age, and radioactive contamination of the equipment within K-25 pose costs that are simply beyond any imaginable resources. Several proposals are on the table, and both local and national preservationists are working with the government to find a suitable solution. Meanwhile, the K-25 plant has almost entirely been torn down, as have many support structures on the site.
Note: All photographs used are U.S. government photographs and are in the Public Domain.