Initial comparison of leach behavior between fully radioactive and simulated nuclear waste glass through long-term testing. Part 2. Reacted layer analysis

An initial comparison of glass behavior of simulated nuclear waste glasses has been made through long-term testing of general glass types SRL165, SRL131 and SRL200. The data demonstrate that up to 560 days at S/V of 2000/m, the reacted layers consist of one outer clay layer, which is undermined by discontinuous etch pits. The regions between the etch pits are alkali depleted. The surface layer becomes thicker as test duration progresses and the reacted layer after the same test time is thinner at higher S/V than at lower S/V. The relative glass durability measured by the thickness of the reacted layer is 165/42S > 131/11S > 200S, which is consistent with solution analyses. In general, the reacted layers on all glass compositions are poorly crystallized which makes the clay identification difficult. The diffraction spacings and EDS compositions for 131/11S and 200S, although not unique to, are consistent with Na (or Ca-) montmorillonite or nontronite. Both of these are dioctahedral smectites. (author)