Editing Nuclear reprocessing (section)

===== Bismuth phosphate =====
The [[bismuth phosphate process]] is an obsolete process that adds significant unnecessary material to the final radioactive waste. The bismuth phosphate process has been replaced by solvent extraction processes. The bismuth phosphate process was designed to extract [[plutonium]] from aluminium-clad [[nuclear fuel rod]]s, containing uranium. The fuel was decladded by boiling it in [[caustic soda]]. After decladding, the uranium metal was dissolved in [[nitric acid]].

The plutonium at this point is in the +4 oxidation state. It was then precipitated out of the solution by the addition of [[bismuth nitrate]] and [[phosphoric acid]] to form the bismuth phosphate. The plutonium was [[coprecipitation|coprecipitated]] with this. The [[supernatant]] liquid (containing many of the [[fission products]]) was separated from the solid. The precipitate was then dissolved in nitric acid before the addition of an [[oxidant]] (such as [[potassium permanganate]]) to produce PuO<sub>2</sub><sup>2+</sup>. The plutonium was maintained in the +6 [[oxidation state]] by addition of a [[dichromate]] salt.

The bismuth phosphate was next re-precipitated, leaving the plutonium in solution, and an iron(II) salt (such as [[ferrous sulfate]]) was added. The plutonium was again re-precipitated using a bismuth phosphate carrier and a combination of [[lanthanum]] salts and [[fluoride]] added, forming a solid lanthanum fluoride carrier for the plutonium. Addition of an [[alkali]] produced an oxide. The combined lanthanum plutonium oxide was collected and extracted with nitric acid to form plutonium nitrate.<ref>{{cite web |url=http://www.bonestamp.com/sgt/process.htm |title=The plutonium production story at the Hanford Site: processes and facilities history (WHC-MR-0521) (excerpts) |publisher=Department of Energy |author=Gerber, Michelle |access-date=7 January 2006 |archive-date=11 May 2006 |archive-url=https://web.archive.org/web/20060511030328/http://www.bonestamp.com/sgt/process.htm |url-status=live }}</ref>