CORROSION BEHAVIOR OF A POWDERED SIMULATED NUCLEAR WASTE GLASS - A CORROSION MODEL INCLUDING DIFFUSION PROCESS

Static corrosion tests were performed with a powdered simulated waste glass in deionized water at 90-degrees-C for periods of up to 130 days . It was observed that normalized elemental mass loss (NL) values for soluble elements (Li, B, Na and Mo) were larger than those for Si by a factor of three and continued to increase after saturation of Si. A c orrosion model (diffusion-combined model), where a diffusion model is combined with a dissolution/precipitation model (reaction path model), was developed and applied to the analysis of experimental results. In the diffusion-combined model, it is assumed that less-soluble element s dissolve into the solution congruently with the silica glass matrix (glass matrix dissolution). On the other hand, it is assumed that solu ble elements diffuse through the glass to the surface and dissolve int o the solution, in addition to the glass matrix dissolution. The diffu sion-combined model can explain the experimental results well, and it is found that the diffusion coefficient is the most effective paramete r determining the corrosion behavior.