Chemical Corrosion of Lead-Iron Phosphate Glass

Abstract

AbstractThis study provides experimental data on the corrosion of lead-iron phosphate (LIP) glass (6.4 wt% LWR waste loading) and the first comparison with the dissolution kinetics of borosilicate (BS) nuclear waste glass (all experiments at 90°C). Based on previous experiments the hypothesis was made that the alteration phenomena and the corrosion mechanism are analogous to what is known for BS glasses. The corrosion rate was found to be constant, 0.06gm−2d−1, at high flow rates (MCC 5 type test), based on total mass loss and on ion conductivity measurements in the leachate. In an MCC 1 type experiment, doped glasses (32p, 210Pb and 137Cs, respectively) were corroded and the release of activity into solution monitored. The release rates were 0.05gm−2 d−1 in the beginning, but decreased drastically when the solution became saturated with respect to Pb(OH)2 and Pb3 (PO4)2. Glass corrosion continued at a low rate as indicated by Cs activity measurements. The higher chemical durability of the LIP glass vs. BS glasses in DI water is a result of a smaller initial corrosion rate (10 to 10O×) and the fact that the saturation concentration is lower for LIP glass, i. e. it takes less dissolved glass (10 to 50×) to reach saturation than in the case of BS glass.