Editing Nuclear reprocessing (section)

====Obsolete methods====
===== 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 The bismuth phosphate process has been replaced by solvent extraction processes.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>

===== Hexone or REDOX =====
This is a liquid-liquid extraction process which uses [[methyl isobutyl ketone]] codenamed hexone as the extractant. The extraction is by a ''solvation'' mechanism. This process has the disadvantage of requiring the use of a [[salting-out]] reagent ([[aluminium nitrate]]) to increase the nitrate concentration in the aqueous phase to obtain a reasonable distribution ratio (D value). Also, hexone is degraded by concentrated nitric acid. This process was used in 1952-1956 on the [[Hanford Site#Separation facilities|Hanford S plant (REDOX plant)]] and has been replaced by the PUREX process.<ref>{{Cite patent|country=US|number=2950166|pubdate=1960-08-23|title=Method for separation of plutonium from uranium and fission products by solvent extraction|assign1=[[United States Atomic Energy Commission]]|inventor1-last=Seaborg|inventor1-first=Glenn T.|inventorlink1=Glenn_T._Seaborg|inventor2-last=Blaedel, Jr.|inventor2-first=Walter J.|inventor3-last=Walling|inventor3-first=Matthew T.}}</ref><ref>{{cite web |url=http://www.llnl.gov/tid/lof/documents/pdf/235702.pdf |title=From separations to reconstitution—a short history of plutonium in the U.S. and Russia (UCRL-JC-133802) |author=L.W. Gray |date=15 April 1999 |publisher=Lawrence Livermore National Laboratory preprint |access-date=7 January 2006 |archive-date=29 November 2007 |archive-url=https://web.archive.org/web/20071129121200/http://www.llnl.gov/tid/lof/documents/pdf/235702.pdf |url-status=live }}</ref>

{{chem2|Pu(4+) + 4NO3(−) + 2S → [Pu(NO3)4S2]}}

===== Butex, β,β'-dibutyoxydiethyl ether =====
A process based on a solvation extraction process using the triether extractant named above. This process has the disadvantage of requiring the use of a salting-out reagent (aluminium [[nitrate]]) to increase the nitrate concentration in the aqueous phase to obtain a reasonable distribution ratio. This process was used at [[Windscale]] in 1951-1964. This process has been replaced by PUREX, which was shown to be a superior technology for larger scale reprocessing.<ref>{{Cite book|last=Taylor|first=Robin|title=Reprocessing and Recycling of Spent Nuclear Fuel|publisher=Woodhead Publishing|year=2015}}</ref>

===== Sodium acetate =====
The sodium uranyl [[acetate]] process was used by the early Soviet nuclear industry to recover plutonium from irradiated fuel.<ref>{{cite journal |last=Foreman |first=Mark R. St J. |title=Reactor accident chemistry an update |journal=Cogent Chemistry |date=2018 |volume=4 |issue=1 |doi=10.1080/23312009.2018.1450944 |doi-access=free}}</ref> It was never used in the West; the idea is to dissolve the fuel in [[nitric acid]], alter the oxidation state of the plutonium, and then add [[acetic acid]] and base. This would convert the uranium and plutonium into a solid acetate salt.

Explosion of the crystallized acetates-nitrates in a non-cooled waste tank caused the [[Kyshtym disaster]] in 1957.