Solubility of Pu and rare-earths in LiCl-Li2O melt

Abstract

Abstract The solubility of Pu and rare-earths (REs) were measured in LiClLi2O melt where individually the oxides precipitated. The solubility of Pu(III) was measured at 923 K as a function of Li2O concentration. After every addition of Li2O to increase the Li2O concentration in the melt, the Pu concentration increased and showed a saturation in several hours. The stepwise variation means that the Pu concentrations at the saturation are regarded as the Pu solubility at the respective Li2O concentrations. The solubility of Nd(III), Gd(III), Pu(IV), and Ce(IV) were also measured as a fanction of Li2O concentration, and all of them increased with increased Li2O concentration. Especially, the solubility of the trivalent Pu and REs were related almost proportionally with the Li2O concentration. The solubility of La(III) and Pr(III) were measured in molten LiCl saturated with Li2O between 883 and 973 K. The logarithmic solubility was related linearly with the reciprocal temperature. The systematic measurement indicated that the solubility was higher for the element with a larger ionic radius as to the trivalent Pu and REs.