Influence of coupled processes on waste package geochemistry

The geochemistry surrounding a waste package is likely to be affected by corrosion of portions of the waste package such as the container. The phenomena involved represent a strong interaction or coupling of corrosion and geochemical processes. A generalized model is developed which can describe the electrochemistry developed in corrosion cells and its interaction with the surrounding geochemical environment. The model is first applied to laboratory data on crevice corrosion and then used to perform a parametric study. The results suggest that all components of the waste package, and their potential interactions must be carefully considered in evaluation of the likely geochemical environment for containment and controlled release of radionuclides. Development of geochemical microenvironments with conditions significantly different from the bulk solution appears likely. Electrical contact between metallic solids can locally raise of lower the potential leading to large accelerations or reductions in corrosion rates. 9 refs., 9 figs