Monday, June 18, 2012


The Y-12 Electromagnetic Separations Plant was one of three installations for the Manhattan Project sited in east Tennessee in 1943. Its mission was to enrich uranium in the fissionable isotope using large electromagnets to accelerate streams of uranium atoms, bending their paths in such a way as to allow atoms of slightly different weights to scatter such that they could be collected separately. (Yes, that is a gross simplification, but I'm an ecologist, not a physicist. For those with chemical backgrounds, they are actually large mass spectrometers.)

The machines that accomplished this separation were called calutrons, and were invented at the University of California by E.O. Lawrence, who received the Noble Prize in Physics in 1939. The chemical element 103 was named lawrencium in his honor, as well. Lawrence's calutrons at Y-12 were arranged into oval assemblages that were nicknamed racetracks, because of their shapes.

Because of the high demand for copper during the war, the electromagnets were instead wound with silver wire, borrowed from the U.S. Treasury. Readers may recall that in 1943 the U.S. was still on the silver standard and our currency was backed by silver reserves held by the treasury. A paper note was imprinted with the words "Silver Certificate," and a person could exchange one for the equivalent amount of silver on demand. So during WWII, our currency was backed by the calutrons at Y-12, at least in part. After the war the silver was reclaimed and returned to the treasury. Congress repealed the silver standard in 1963, and by 1968 currency could no longer be redeemed for silver.

Young women were trained to operate the calutron racetracks, but never told what their jobs actually were. They simply sat in front of panels of dials and controls and made adjustments to keep the readings within an allowable range. They were never allowed to look behind the curtain, and didn't learn what their job was about until after the first bomb was dropped on Hiroshima.

 After the war all uranium enrichment was done by gaseous diffusion, at K-25 and its sister plants. Y-12 continued to operate with other defense missions. Now known as the Y-12 National Security Complex, it is operated by the U.S. Department of Energy through its National Nuclear Security Administration. You can learn more about Y-12 by visiting their web site here. Look at the articles written by Ray Smith, Y-12 historian. They're excellent.

All photographs used are U.S. Government photographs and are in the public domain.


  1. Can you imagine sitting in front of those dials all day long? Ugh. People didn't complain so much in those days though. A job was a job. What would make me crazy though is not knowing what all those dials were for. Don't you think they must have had some suspicion?

    1. No, I can't. I'd get fired for inattention in the first hour. But it was war time, and WWII was very different from any of the wars our generation has known. Then, the whole country went to war, even those who stayed home. As for guessing what they were doing, I doubt it. It would probably take more education than most of those young women had to even suspect what was going on. Atomic energy was not a widely known topic at the time. Talking to older people who were there, some of the technical folks will admit they had their suspicions, but it's hard to say if that's not actually 20-20 hindsight. I tend to think the older we get the better we were!

  2. If they'd hired me to watch the dials the whole history of the world would have been very different and there'd have been a huge crater in east Tennessee.