Corrosion behavior of environmental assessment glass in product consistency tests of extended duration.

We have conducted static dissolution tests to study the corrosion behavior of the Environmental Assessment (EA) glass, which is the benchmark glass for high-level waste glasses being produced at US Department of Energy facilities. These tests were conducted to evaluate the behavior of the EA glass under the same long-term and accelerated test conditions that are being used to evaluate the corrosion of waste glasses. Tests were conducted at 90 C in a tuff groundwater solution at glass surface area/solution volume (WV) ratios of about 2000 and 20,000 m{sup {minus}1}. The glass dissolved at three distinct dissolution rates in tests conducted at 2000 m{sup {minus}1}. Based on the release of boron, dissolution within the first seven days occurred at a rate of about 0.65 g/(m{sup 2} {center_dot} d). The rate between seven and 70 days decreased to 0.009 g/(m{sup 2} {center_dot} d). An increase in the dissolution rate occurred at longer times after the precipitation of zeolite phases analcime, gmelinite, and an aluminum silicate base. The dissolution rate after phase formation was about 0.18 g/(m{sup 2} {center_dot} d). The formation of the same zeolite alteration phases occurred after about 20 days in tests at 20,000 m{sup {minus}}. The average dissolution rate over the first 20 days was 0.5 g/(m{sup 2} {center_dot} d) and the rate after phase formation was about 0.20 g/(m{sup 2} {center_dot} d). An intermediate stage with a lower rate was not observed in tests at 20,000 m{sup {minus}1}. The corrosion behavior of EA glass is similar to that observed for other high-level waste glasses reacted under the same test conditions. The dissolution rate of EA glass is higher than that of other high-level waste glasses both in 7-day tests and after alteration phases form