Wednesday, August 31, 2011


On Monday I remarked about the government taking land in what is now Oak Ridge, Tennessee, for the wartime Manhattan Project. Some 92 square miles of what was then sparsely-settled farm land, including three communities, were cleared of people and a fence erected around the perimeter. Inside this space were built 3 industrial plants (code-named K-25, X-10, and Y-12) that formed the largest of the three sites devoted to the race to build an atomic weapon.

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:
Some 12,000 construction workers were involved in building the plant between June 1943 and its completion early in 1945. Many were housed in a temporary construction camp nearby (lower right of photo below) that was dubbed "Happy Valley," allegedly because of its enormous birth rate.
The government eventually built two more gaseous diffusion plants at the K-25 site, and plants near Paducah, KY, and Portsmouth, OH, which provided fuel for commercial power reactors as well as military needs. By the 1980s, there was significant over capacity and the Oak Ridge plants were shut down. The K-25 site is now being decontaminated and demolished, with the land being made available for commercial development.

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.


  1. It worries me that they build these things without any real thought as to how they will deal with them in the long-term. It still goes on. Having said that, it was clearly an awesome project - what a huge place.

  2. This was a fascinating post -- barbara