Recovery of eu2+ and sr2+ using liquid metallic cathodes in molten nacl-kcl and kcl system

Abstract

In the pyrochemical reprocessing of spent metallic nuclear fuels using molten salt bath, recovery of Eu and Sr as fission products having electrochemically negative potentials is important. In order to develop the electrowinning method, cathodic deposition of Eu2+ in the NaCl-KCl melt and Sr2+ in the KCl melt at some metallic cathodes (Al, Bi, Pb, Sn and Zn) was examined by cyclic voltammetry and chronopotentiometry. Transfer coefficient, standard rate constant and diffusion coefficient for Eu2+ and Sr2+ were determined by cyclic voltammetry with conventional, semi-integral and semi-differential methods and by chronopotentiometry. It was revealed that a quasi-reversible cathodic reaction Eu2+ +2e− +3Pb → EuPb3 on liquid Pb electrode takes place in the NaCl-KCl melt at 1,073K. As for Sr2+, a quasi-reversible cathodic reaction Sr2+ +2e− +3Pb→SrPb3 takes place at liquid Pb electrode in the KCl melt at 1,073K. These propose possibility to recover Eu into Pb cathode and Sr into Pb cathode as well as into Al cathode. © 1997 Taylor and Francis Group, Ltd.