Overcoming the Odds

Kellex President Percival Keith and chemical engineer John Arnold discuss the difficulty of designing a first-a-kind compressor that could handle the highly toxic uranium hexaflouride gas.

Narrator: The challenges posed by uranium hexafluoride were daunting. It was a gas, highly corrosive and violently explosive when it came into contact with air, water or oil. Equipment had to be absolutely air tight and operate in a vacuum far below normal atmospheric pressure. Shafts had to operating beyond the speed of sound with no lubricant. There were no precedents for such a machine. The engineers had to rely upon trial and error and their native ingenuity.

Percival Keith: There had to be a great number of them made, a very great number, running into the thousands. They had to be centrifugal compressors. They had to be absolutely tight. They had to operate, of course, with a highly corrosive gas. To be practical, the impeller had to operate beyond the speed of sound in this gas.

John Arnold: One of our biggest problems was corrosion—both corrosion of the internals of the containers and also the corrosion of the barrier. Part of this was the in-leakage of air through the rotating seals. You have seen in a motorboat with the propeller sticking out the back and the little stuffing box that seals that shaft so that the water doesn’t come into the boat? Well, these seals were somewhat more sophisticated, but they were on centrifugal compressors or pumps, as they were called, to prevent the air from leaking into the process, which was run under vacuum.

Designing state-of-the-art compressors for the K-25 gaseous diffusion plant required ingenuity and perserverance against all odds. 

Narrator: Many vital needs were not available or simply did not exist when the Manhattan Project was begun. Case and point, compressors.

Percival Keith: There were no compressors available. No design available. Nobody thought the damn thing could be done. We sat down, the four of us, and agreed that it could be done. The only reason why it couldn’t be done: nobody could prove to us it would not work and we had to assume then that it would work, that we were sound engineers and we knew something about centrifugal machinery.

I went to the Clark Company, I went to Worthington Pump and Machinery and I went to Ingersoll Rand. All three of those companies just turned the job down and said it could not be done. It had not been done before. We were looking for a compression ratio, which was quite high for a single impeller, very high.

John Arnold: There were no such things in existence which would meet the requirements of the real low in leakage. We could only tolerate a very, very minor amount of particularly moisture getting in, otherwise the moisture in the hexafluoride would react in a way to cause solids, which would plug up the holes.

Narrator: With the help of General Groves, Keith finally convinced the Allis-Chalmers Corporation to design the compressors in a brand new factory that would be built and paid for by the Manhattan Engineers District.

Percival Keith compares the design and manufacture of more than one thousand compressors for K-25 to the battle campaign of the great Albrecht von Wallenstein, whose war against Gustavus Adolphus of Sweden required the execution of “several minor miracles and theories.”

Narrator: To design and manufacture more than one thousand compressors in less than one year, extraordinary engineers applied their talents to unprecendented, out-of-the-box ideas.

Percival Keith: Well it was tense all the way through. I think it was Gustav [Adolphus] the Snow King who had the great war with Wallenstein. Wallenstein led an army into what is now Austria-Hungary, and writing back to his wife he said that he finally had reached a feasible way of conducting his campaign and capturing these several cities. And that this was a possible scheme because it only required the execution of several minor miracles and theories. Well, the job at Oak Ridge required the execution of a number of minor miracles and theories, and this was one of them.

Physicist Phillip Abelson invented a new way to separate uranium istopes known as liquid thermal diffusion.

Narrator: In June of 1944, Manhattan Project scientists were still struggling to produce enriched uranium pure enough to be used in an atomic bomb. At the Philadelphia Navy Yard, physicist Phillip Abelson invented a new way to separate isotopes. The process, known as liquid thermal diffusion, was deceptively simple.

Phillip Abelson: All it consisted of was three concentric pipes. This is all you had to put together and put heat in the middle and cool on the outside and uranium isotopes separate in between. The light goes to the hot and climbs, and the heavy goes down, so that all one has to do is to fill this thing and put steam in and cooling water and go away for three days and one has separation. It worked!