Experimental and theoretical progress on the reduction of Np(vi) with salt-free reagents in the PUREX process

Abstract

Effectively controlling the oxidation state of neptunium (Np) is crucial for the separation of Np during the advanced plutonium uranium reduction extraction process. The reduction reactions and kinetics of Np(VI) with salt-free reagents were explored by applying experimental and theoretical studies. This review summarizes the reduction reaction, kinetics, mechanism and electronic structures as well as the potential energy surfaces of Np(VI) to Np(V) using salt-free reagents, such as hydrazine, hydroxylamine, aldehydes, oximes, hydroxamic acids and their derivatives. This review will hopefully serve as a useful resource to inspire further research on the reduction of Np(VI) using salt-free reagents.

Keywords: Reduction kinetics; Reduction mechanism; Np(VI); Salt-free reagents; Theoretical simulation.