Basicity of melts for the immobilization of high-level radioactive waste

The key to better understanding of the physico-chemical properties of melts consisting of glass and high-level nuclear waste for immobilization is a measure of oxide anion activities. Nevertheless thermochemical activities of single ions are, in principle, not measurable. Hence, it is obliged to evaluate oxide anion activities through measurable quantities such as CO₂ solubilities and Fe_xO activities. In this paper, based upon available literature data on metallurgical slags, an overview is given on correlation between oxide anion activities and such measurable quantifies, with a particular intention to apply for high-level waste+glass melts. For (high-level waste+glass) melts a knowledge of Fe_xO solubility can be a relative measure of oxide anion activity. (author)