PUREX

PUREX is a chemical method used to purify fuel for nuclear reactors or nuclear weapons. It is an acronym standing for Plutonium Uranium Redox EXtraction. PUREX is the de facto standard aqueous nuclear reprocessing method for the recovery of uranium and plutonium from used ("spent", or "depleted") 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.

The spent nuclear fuel to which this process is applied consists primarily of certain very high atomic-weight (actinoid or "actinide") elements (e.g. uranium) along with smaller amounts of material composed of lighter atoms, notably the so-called fission products.

The actinoid elements in this case consist primarily of the largely unconsumed remains of the original fuel (typically U-238 and other isotopes of uranium). In addition there are smaller quantities of other actinoids, created when one isotope is transmuted into another by a reaction involving neutron capture. Plutonium-239 is the leading example. Another term sometimes seen in relation to this secondary material (and other material produced similarly) is activation products.

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