Plutonium chemical properties in NaCl–KCl and CaCl2 at 1073K

Abstract The electrochemical properties of plutonium have been studied in molten equimolar NaCl/KCl and CaCl 2 at 1073 K by cyclic voltammetry. The respective standard potentials of Pu(III)/Pu redox couple, −2.54 V and −2.51 V (versus Cl − /Cl 2 reference electrode), led to the calculation of the activity coefficients of Pu(III) in each electrolyte. In CaCl 2 the complexation of Pu(III) ions is lower and the voltage gap between Pu(III)/Pu redox system and the solvent limit is higher. Use of these results to construct potential–pO 2− diagrams for plutonium at 1073 K gives a rational overview of plutonium properties in these media.