Dissolution mechanisms of nuclear waste glasses

Mass loss of elements from nuclear waste glasses is the combined result of both bulk dissolution and leaching of the glass surface combined with a mass transport process to insert the released elements into the fluid flow field. Leaching and hydration produce a transient hydrated layer that may crystallize into less soluble reaction-product phases. Several proposed dissolution kinetic models are compared, particularly with regard to the effect of pH and the role of silica saturation in blocking additional dissolution. Surface layers may also produce diffusive barriers to further dissolution. All dissolution mechanisms examined exhibit Arrhenius behavior: rates increase exponentially with temperature