ABSTRACT
Over the last 50 years, the principal reason for reprocessing used fuel has been to recover unused uranium (U) and plutonium (Pu) in the used fuel elements and thereby avoid the wastage of a valuable resource. Most of the used fuel-about 96% is uranium at <1% U-235 and up to 1% is 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). Reprocessing is preformed in several countries using the plutonium and uranium recovery by extraction PUREX (originally “Plutonium Uranium Extraction” but also found in the literature as “Plutonium Uranium Recovery by Extraction” or “Plutonium Uranium Reduction Extraction”) process (Table 11.1). The legacy of the massive volume of waste generated during these many years of aqueous processing to recover actinide from spent fuel, as well as the cost of reprocessing, have spurred efforts to develop new aqueous processes or radically different approaches.
