Addition of transition metal oxides on silver tellurite glass for radioactive iodine immobilization

The long-lived radioactive forms of iodine pose significant environmental threats. Therefore, it is important to capture and immobilize radioactive iodine. In this study, an iodine immobilization matrix was developed and investigated by adding transition metal oxides such as WO3, MoO3, and V2O5 to the AgI-Ag2O-TeO2 glass system. The immobilization was confirmed by melting the glass precursor mixtures at 800°C for 1 h without a significant loss of the elements that comprising the glass. The loading of iodine in the matrix was approximately 13-15% by weight, excluding elemental oxygen. The normalized releases of all the elements obtained by PCT-A were below 10−1 g/m2, thereby satisfying the USA regulations (2 g/m2). The structural factors related to the chemical durability of the glass were discussed. The addition of WO3, MoO3, and V2O5 suppressed the release of iodine by densifying the TeO4 polyhedra. The silver release was not significantly affected by increasing the concentrations of the transition metal oxides. The additives stabilized tellurium, which is a glass network former, to prevent its release from the glass matrix. All the transition metals considered in this study remained stable in the silver tellurite glass in comparison to the release of tellurium.