Bismuth phosphate process
The bismuth-phosphate process was used to extract plutonium from irradiated uranium taken from nuclear reactors.
[1][2] It was developed during World War II by Stanley G. Thompson, a chemist working for the Manhattan Project at the University of California, Berkeley.
Chemists explored a variety of methods for separating plutonium from the other products that came out of the reactor: While the chemical engineers worked on these problems, Seaborg asked Stanley G. Thompson, a colleague at Berkeley, to have a look at the possibility of a phosphate process because it was known that the phosphates of many heavy metals were insoluble in an acid solutions.
He did not expect bismuth phosphate (BiPO4) to work any better, but when he tried it on 18 December 1942, he was surprised to find that it carried 98 percent of the plutonium in solution.
[9] In May 1943, the DuPont engineers decided to adopt the bismuth phosphate process for use in the Clinton semiworks and the Hanford production site.
The bismuth phosphate process involved taking the irradiated uranium fuel slugs and removing their aluminium cladding.
Because there were highly radioactive fission products inside, this had to be done remotely behind a thick concrete barrier.
Liquid was removed with a centrifuge and the solid dissolved in nitric acid to form plutonium nitrate.
This was dissolved in nitric acid and put into shipping cans, which were boiled in hot air to produce a plutonium nitrate paste.
[18] Shipments were made in a truck carrying twenty cans and the first arrived at Los Alamos on 2 February 1945.
[20] In 1947, experiments began at Hanford on a new REDOX process using methyl isobutyl ketone (codenamed hexone) as the extractant, which was more efficient.
