PUREX is an acronym standing for Plutonium - URanium EXtraction — de facto standard aqueous nuclear reprocessing method for the recovery of uranium and plutonium from used nuclear fuel. It is based on liquid-liquid extraction ion-exchange.
The PUREX process was invented by Herbert H. Anderson and Larned B. Asprey at the Metallurgical Laboratory at the University of Chicago, as part of the Manhattan Project under Glenn T. Seaborg; their patent "Solvent Extraction Process for Plutonium" filed in 1947, mentions tributyl phosphate as the major reactant which accomplishes the bulk of the chemical extraction.
Read more about PUREX: Overview, Chemical Process, Pollution, List of Nuclear Reprocessing Sites, See Also