Corrosion behavior of a powdered simulated nuclear waste glass under anoxic condition

Static corrosion tests were carried out with a powdered simulated waste glass in deionized water at 90 °C under oxic and anoxic conditions, respectively. The corrosion tests under anoxic condition were performed in a globe box purged with mixed gas (N₂+5%H₂), where the pH and Eh of deionized water were maintained at 6.9 and -0.35 V vs. S.H.E. at 25 °C, respectively. It was observed that there is a little difference between NL values under oxic and anoxic conditions. For soluble elements (Li, B, Na, Mo) and Ca, NL values under anoxic condition were slightly smaller than those under oxic condition. For Fe and Al, NL values under anoxic condition were slightly larger than those under oxic condition. For Si, Ce, La and Nd, there was no difference between NL values under oxic and anoxic conditions. The experimental results were analyzed on the basis of a corrosion model (Diffusion-combined Model), in which the solution concentration of elements associated with solution pH and Eh can be derived thermodynamically by use of PHREEQE. The analysis suggests that precipitating minerals controlling the solution concentrations of Fe and Ca under anoxic condition are different from those under oxic condition.