ABSTRACT
Over the past 50 years, the principal reason for recycling used nuclear fuel (UNF) has been to recover unused uranium (U) and plutonium (Pu) in the used fuel elements, thereby avoiding the wastage of a valuable resource. Most of the used fuel—about 95% uranium at 1% U-235 and up to 1% plutonium—can be recycled as fresh fuel, saving some 30% of the natural uranium otherwise required. It also avoids leaving the plutonium in the used fuel, where in a century or two the built-in radiological protection will have diminished, possibly allowing it to be recovered for illicit use (though it is unsuitable for weapons due to the nonfissile isotopes present). UNF recycling is performed in several countries using the plutonium and uranium recovery by the PUREX (originally “Plutonium Uranium Extraction” but also found in the literature as “Plutonium Uranium Recovery by Extraction” or “Plutonium Uranium Reduction Extraction”) process (Table 14.1).
