Treatment of spent nuclear reactor fuel to recover the unconsumed uranium-235 and plutonium by separating them from each other and from the fission products formed in the reactor. The Purex process is the accepted procedure used for this purpose. The spent fuel is dissolved in nitric acid; separation is effected by solvent extraction with tributyl phosphate, ion-exchange reactions, and precipitation. The reclaimed uranium-235 and plutonium are sent to fuel fabrication plants for reuse. The fission product waste is evaporated and stored. Another method, called the Civex process, has been proposed to prevent theft of plutonium; here the mixture of waste products, uranium isotopes, and plutonium is not separated. Since its plutonium content is only 20% it could not be used for weapons; the mixture is suitable for fast breeder reactors. Serious radiation hazards are involved in reprocessing and require use of appropriate shielding and remote-control handling procedures. Storage of the radioactive waste also presents a long-range problem that has not yet been satisfactorily solved. There are no commercial reprocessing plants operational in the U.S., though there are several in Europe.See Radioactive Waste; Breeder.
