Recovery of actinides and fission products from spent nuclear fuel via electrolytic reduction: Thematic overview

Abstract

Spent nuclear fuel (SNF) from modern light water or thermal reactors containing uranium oxide with small concentrations of plutonium and other actinide oxides is converted into metal by the electrolytic reduction. The obtained metal must be subjected to further processing (electrorefining). This review reflects the achievements in development SNF electrolytic processing, concepts of the technological operations, and a model describing the electrochemical process. The technological scheme for the electrochemical reduction of SNF and MOX fuel is considered. The complexity of a carbon anode application in the process of UO2 electrolytic reduction is reflected. The reduction processes of alkali, alkaline earth (AE), and rare earth metal oxides as well as oxide compounds of zirconium are demonstrated. The reduction of lanthanum oxide and oxy-chloride to the metallic form by adding metallic nickel to the molten salt is discussed. The solubility of Li2O in molten salts is interpreted depending on the amount of dissolved alkali and AE metal chlorides. The considered pyroprocessing technology enables a much greater release of the energy accumulated in uranium ore, and recycling all actinides allows reducing significantly the amount of nuclear waste and the time it must be isolated. © 2021 John Wiley & Sons Ltd.