Corrosion behavior of environmental assessment glass in product consistency tests211 of extended duration

摘要

We have conducted static dissolution tests to study the corrosion behavior of the211u001eEnvironmental Assessment (EA) glass, which is the benchmark glass for high-level 211u001ewaste glasses being produced at US Department of Energy facilities. These tests 211u001ewere conducted to evaluate the behavior of the EA glass under the same long-term 211u001eand accelerated test conditions that are being used to evaluate the corrosion of 211u001ewaste glasses. Tests were conducted at 90 C in a tuff groundwater solution at 211u001eglass surface area/solution volume (WV) ratios of about 2000 and 20,000 m(sup 211u001e(minus)1). The glass dissolved at three distinct dissolution rates in tests 211u001econducted at 2000 m(sup (minus)1). Based on the release of boron, dissolution 211u001ewithin the first seven days occurred at a rate of about 0.65 g/(m(sup 2) (center 211u001edot) d). The rate between seven and 70 days decreased to 0.009 g/(m(sup 2) 211u001e(center dot) d). An increase in the dissolution rate occurred at longer times 211u001eafter the precipitation of zeolite phases analcime, gmelinite, and an aluminum 211u001esilicate base. The dissolution rate after phase formation was about 0.18 g/(m(sup 211u001e2) (center dot) d). The formation of the same zeolite alteration phases occurred 211u001eafter about 20 days in tests at 20,000 m(sup (minus)). The average dissolution 211u001erate over the first 20 days was 0.5 g/(m(sup 2) (center-dot) d) and the rate 211u001eafter phase formation was about 0.20 g/(m(sup 2) (center-dot) d). An intermediate 211u001estage with a lower rate was not observed in tests at 20,000 m(sup (minus)1). The 211u001ecorrosion behavior of EA glass is similar to that observed for other high-level 211u001ewaste glasses reacted under the same test conditions. The dissolution rate of EA 211u001eglass is higher than that of other high-level waste glasses both in 7-day tests 211u001eand after alteration phases form.