Electrochemical extraction of the fission element samarium from tin electrodes and its kinetic analysis in an electrolytic refining process in LiCl-KCl molten salts

Abstract

The key fragment element samarium (Sm) has a large neutron absorption cross section, which can hinder the absorption of neutrons by uranium and negatively affect the nuclear reaction. In order to realize the nuclear fuel cycle, the extraction of Sm was studied on the basis of electrolytic refining after the dry process. The electrochemical properties of SmCl3 and SnCl2 in LiCl-KCl molten system were systematically investigated by cyclic voltammetry (CV), square wave voltammetry (SWV), and open circuit potential (OCP). The diffusion coefficients of the Sn(II) and Sm(III) electrode processes were calculated to be 3.55–5.93 × 10−5 and 2.33–3.97 × 10−5 cm2 s−1, respectively. The co-reduction of Sm(III) and Sn(II) ions was studied. Sm was recycled by constant current electrolysis on the liquid Sn electrode, and the average extraction rate was about 94.23%. The samples were characterized and analyzed by X-ray diffraction analysis (XRD) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM), and the results showed that Sm extraction from liquid tin is feasible.