Impact of initial states on the vapor hydration of iodine-bearing borosilicate glass

Under the context of long-term geological disposal of nuclear waste glass, the present work investigates the effect of initial states on the glass chemical durability in the vapor phase and during subsequent leaching. Glass with different finishing steps of polishing and thermal annealing were prepared, vapor-hydrated, and aqueous-altered. Multiple characterizations of mechanical properties and structural modifications were performed to understand the reduction of vapor hydration rates with annealed glasses. Discussions on the degradation of mechanical properties provide insights to understanding the variations of glass chemical durability, which shows a feasible approach to link mechanical and chemical studies together. By looking into the release of boron in the vapor phase, similarities between glass vapor hydration and glass aqueous alteration at residual rate are noticed, which allow the proposition of mechanisms of boron release. Characterizations of the hydrated-then-altered glass reveal the transport-limiting property of the vapor hydrated layer. (authors)