An Independent Method for Data Selection of Long-life Radionuclides (Actinides and Fission Products) in the Geosphere

Abstract

An independent method for data selection of long-life radionuclides based on the electronegativity equalization principle is proposed to predict the speciation of metal cations as a function of the solution pH. Hydrolysis, condensation and complexation reactions of metal cations in aqueous media are, by this simple model, unified and can be analyzed in terms of electronegativities, oxidation states and coordination numbers with a specific PC software. This paper describes the thermodynamical basis and the underlying concepts of the model in relation to the aqueous actinide chemistry of elements such as U and Tc. It is then shown that the model could provide a complementary approach to existing softwares based on thermodynamic data bases allowing to make intelligent and reasonnable choices for the various complexes to consider in complex geochemical codes.