Thermodynamic and Structural Models Compared with the Initial Dissolution Rates of “SON” Glass Samples

Abstract

The experimentally determined initial dissolution rate R₀ of nuclear glass was correlated with thermodynamic parameters and structural parameters. The initial corrosion rates of six “R7T7” glass samples measured at 100°C in a Soxhlet device were correlated with the glass free hydration energy and the glass formation enthalpy. These correlations were then tested with a group of 26 SON glasses selected for their wide diversity of compositions. The thermodynamic models provided a satisfactory approximation of the initial dissolution rate determined under Soxhlet conditions for SON glass samples that include up to 15 wt% of boron and some alumina. Conversely, these models are inaccurate if the boron concentration exceeds 15 wt% and the glass contains no alumina. Possible correlations between R₀ and structural parameters, such as the boron coordination number and the number of nonbridging oxygen atoms, were also investigated. The authors show that R₀ varies inversely with the number of 4-coordinate boron atoms; conversely, the results do not substantiate published reports of a correlation between R₀ and the number of nonbridging oxygen atoms.