Early stages of film formation during the leaching of radioactive waste glasses

The early stages of surface alteration-layer formation were examined during the leaching of some candidate radioactive waste glasses. The composition-depth profiles of the leached surfaces were obtained with sputter-induced photon spectroscopy (SIPS) and secondary-ion mass spectroscopy (SIMS). It was observed that the formation of multiple surface layers is a general feature of the glass dissolution process. The sequence of the layer compositions depends upon the order in which solubility limits are attained in solution, the adsorption or precipitation of insoluble hydrates at the glass/water interface, and subsequent incorporation of these insoluble hydrates at the glass/water interface, and subsequent incorporation of these insoluble hydrates behind the advancing reaction front. The boundary between the surface layer and bulk glass is sharp. 8 refs., 5 figs