Radiation effects on the structure and alteration behavior of an SiO₂–Al₂O₃–B₂O₃–Na₂O glass

Abstract

As borosilicate glasses are used in many countries to immobilize fission products and minor actinides after spent fuel reprocessing before storage in a deep geological repository, assessing that their chemical durability is of paramount importance. Here, pristine and preirradiated (952 MeV, 136Xe) SiO 2 -B 2 O 3 -Al 2 O 3 -Na 2 O glasses with the same molar ratios as in the French SON68 and ISG glasses have been subjected to aqueous corrosion in deionized water and in silica-saturated solution to measure the initial and longer term alteration rates. Pristine and preirradiated glasses corrode following the same mechanisms, but the preirradiation has a strong impact on the initial dissolution rate (increase by a factor of 5.6), and on the alteration layer depth in silica-saturated conditions (by two-to threefolds). The later result is related to the formation of a more porous, less passivating gel on the preirradiated glass specimen. Using both experimental spectroscopies (NMR, IR, and SFG) and classical molecular dynamics, the radiation effects on the glass structure and water diffusion have been assessed. After preirradiation, the density and the polymerization degree of the glass decrease, whereas the topological disorder increases. In consequence, water diffusion accelerates. These observations allow to correlate the radiation impact on the alteration behavior to the structural changes.

Effect of structural disorder induced by external irradiation with heavy ions on the alteration of a four oxide borosilicate glass

“…Meanwhile, the uncertainty in the calculated thickness from the solution analysis arises from the estimation of the reactive surface and the analysis of the B concentration in the solution. These results are in line with previous studies showing that in the tested conditions CJ2 glass alters forming only a gel layer that replace the glass keeping constant the volume occupied by the solids 30,33,44,46 .…”

“…The uncertainty in these rates is 30%, as suggested in a previous study on ISG glass 43 . This effect of irradiation on initial dissolution rate is in line with previous studies conducted on simple borosilicate glasses, showing an increase of the rate related to the structural changes induced by irradiation 21,24,44 .…”

Composition‐dependent leaching behavior in ion‐irradiated borosilicate glasses: A corrosion mechanism study

“…observed an increase in the dissolution rate of borosilicate glass after irradiation. However, the consensus remains that the initial mechanisms of water–glass interaction are consistent for both pristine and irradiated borosilicate glass 20 …”

“…However, the consensus remains that the initial mechanisms of water-glass interaction are consistent for both pristine and irradiated borosilicate glass. 20 Furthermore, the composition of the glass itself plays a crucial role in determining its leaching behavior. 21 The effects of irradiation on glasses of different compositions under leaching conditions have garnered significant attention, underscoring the need for more in-depth studies on the corrosion mechanisms of various irradiated borosilicate glasses.…”