Glass reactivity in aqueous solutions

Surface analysis methods have been incorporated as part of several studies concerning the mechanisms and amount of glass leaching in aqueous solutions. The reactivity of simple glasses with water has been determined by measuring the uptake of D and ¹⁸O in soda‐lime silicate glass, amorphous and crystalline silica, and amorphous and crystalline albite leached in D₂¹⁸O at 90 °C as a function of time. The concentrations and profiles of ¹⁸O and D going into the glass were determined using nuclear reaction analysis and compared to the material leached from the glass as determined by solution and Rutherford backscattering (RBS) analyses. The measured ratio of D/¹⁸O does not follow any one simple uptake model. Reaction layers formed on simulated nuclear waste glasses containing Pu have also been measured using RBS. Specimens were leached in deionized water or brine at 90 °C. The concentration of Pu on the specimens generally decreased with time. Analysis of the leaching solution indicated that the rate of Pu release was considerably less than that of the glass matrix. The results support the buildup of a surface layer covering the Pu.