Comparison of glass reaction at high and low SA/V: PCT vs MCC-1

摘要

Leach tests have been performed at surface area/volume (SA/V) of 10, 2000, and 20,000 m(sup (minus)1) using actinide-doped borosilicate waste glass (SRL 131 and SRL 202) to assess the effects of the SA/V on the mechanism and rate of the glass reaction. Solution results are presented which show the major effect of the SA/V to be dilution. Higher SA/V result in higher leachate pH values being attained due to initial ion exchange reactions. The higher pH values then accelerate hydrolysis of the glass. Colloids rich in aluminum and iron form at high SA/V after very little glass has reacted. Actinides released during glass reaction sorb onto these colloids which eventually become large enough to settle out of solution. The measured response is sensitive to the SA/V of the test, and is dominated by ion exchange at 10 m(sup (minus)1), by matrix dissolution at 2000 m(sup (minus)1), and by colloid formation at 20,000 m(sup (minus)1) within laboratory test timeframes.