SEABORG AND PLUTONIUM CHEMISTRY
Met Lab (1942-1944)
Events: The Plutonium Path to the Bomb, 1942-1944

While the Met Lab labored to make headway on pile (reactor) design, Glenn T. Seaborg (right) and his coworkers were trying to learn enough about transuranium chemistry to ensure that plutonium could be chemically separated from the uranium that would be irradiated in a production pile.  Using lanthanum fluoride as a carrier, Seaborg isolated a weighable sample of plutonium in August 1942.  At the same time, Isadore Perlman and William J. Knox explored the peroxide method of separation; John E. Willard studied various materials to determine which best adsorbed (gathered on its surface) plutonium; Theodore T. Magel and Daniel K. Koshland, Jr., researched solvent-extraction processes; and Harrison S. Brown and Orville F. Hill performed experiments into volatility reactions.  Basic research on plutonium's chemistry continued as did work on radiation and fission products.  

Seaborg's discovery and subsequent isolation of plutonium were major events in the history of chemistry, but it remained to be seen whether they could be translated into a production process useful to the bomb effort.  The laboratory process created by Seaborg would have to be scaled-up a billion-fold to be implemented in an industrial separation plant.  

Collaboration with DuPont's Charles M. Cooper and his staff on plutonium separation facilities began even before Seaborg succeeded in isolating a sample of plutonium.  Seaborg was reluctant to drop any of the approaches then under consideration, and Cooper agreed.  The two decided to pursue all four methods of plutonium separation but put first priority on the lanthanum fluoride process Seaborg had already developed.  Cooper's staff ran into problems with the lanthanum fluoride method in late 1942, but by then Seaborg had become interested in phosphate carriers.  Work led by Stanley G. Thompson found that bismuth phosphate retained over ninety-eight percent plutonium in a precipitate.  With bismuth phosphate as a backup for lanthanum fluoride, Cooper moved ahead to create an experimental production facility near Stagg Field.  

By late 1942, experiments with the lanthanum fluoride process in Chicago had gone well enough that DuPont moved into the plant design stage and converted the facility at the Met Lab to experiment with the use of bismuth phosphate.  In late May 1943, DuPont pushed for a final decision on which of the two processes to use.  Greenewalt chose bismuth phosphate (right), even though Seaborg admitted he could find little to distinguish between the two.  Greenewalt based his decision on the corrosiveness of lanthanum fluoride and on Seaborg's guarantee that he could extract at least fifty percent of the plutonium using bismuth phosphate.  DuPont began constructing the chemical separation pilot plant at Oak Ridge, while Seaborg continued refining the bismuth phosphate method.  

It was now Cooper's job to design the new experimental production pile as well as the plutonium extraction facilities at Oak Ridge, both complicated engineering tasks made even more difficult by high levels of radiation produced by the process.  Not only did Cooper have to oversee the design and fabrication of parts for yet another new Manhattan Project technology, he had to do so with an eye toward planning the Hanford facility.  Radiation safety was a major consideration because of the hazards of working with plutonium, which was highly radioactive.  Uranium, a much less active element than plutonium, posed far fewer safety problems.