Iodine 129 is a radioactive waste coming from the nuclear industry. Due to its high volatility, it cannot be vitrified in conventional borosilicate glasses. As a part of the assessment of alternative solutions, this work focuses on the study of the feasibility of iodine conditioning using a glass matrix aiming at a long-term storage in a geological repository. Silver phosphate glasses, which can incorporate high amounts of iodine and can be synthesized at low temperature, were chosen for this study. In order to increase their chemical durability, theses glasses were crosslinked by niobium and bismuth oxides. Niobium and bismuth incorporation limits were determined for an iodine amount of 12 wt% and range from 1.6 mol% to 4.0 mol%, depending on the Ag2O/P2O5 ratio. The glasses polymerization state was investigated using 31 P MAS NMR, RAMAN spectroscopy and X-ray absorption spectroscopy. Iodine local environment was determined by EXAFS at iodine K-edge.Structural investigations show that the introduction of those crosslinking reagents induces a significant increase of the polymerization degree of the glasses. However, despite this higher connectivity, the two crosslinking reagents have a low impact on the glass transition temperature of iodine-containing silver phosphate glasses.

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