Redox behavior of ruthenium in nuclear glass melt: ruthenium dioxide reduction reaction

摘要

Among platinoid fission products, ruthenium is a key element during the vitrification of high-level waste because it is poorly soluble in the glass matrix. It occurs mainly as RuO2 particles and sometimes as Ru-0 particles in the glass melt and final cooled glass. Because the physical properties of ruthenium are very different from those of glass, the RuO2 particles change the glass melt properties such as the rheology, thermal conductivity and electrical conductivity. In addition, because the Ru-0 properties are even more distinct from the glass properties, glass melts can be more sensitive to the presence of Ru-0 particles. Thus, ruthenium speciation, specifically the RuO2 reduction into Ru-0, was investigated in air and glass environments, and the experimental results were compared to thermodynamic calculations (Calphad method).