Nuclear industry uses glass matrices for long-lived nuclear wastes immobilization; in particular borosilicate composition is the glass reference for such wastes. However, immobilization of I-129 in borosilicate glasses can be difficult, due to high glass processing temperature. This work aims at understanding phosphate glasses for 129I wastes. Phosphate glass can be prepared at lower temperature (under 700�C) allowing for minimization of iodine volatilization and incorporation of high iodine contents. In the present study, the structure and thermal properties of AgI-Ag2O-P2O5-Al2O3 glass system have been studied and chemical durability (i.e., aqueous resistance) determined. The effects of the incorporation of Al2O3 (up to 5 mol%) and silver iodide (up to 30 mol%) on micro and local structures were measured. An absence of AgI clusters within the glass was clearly demonstrated and a shortening of phosphate chains upon AgI incorporation was also proven. However, the formation of aluminophosphate-based crystallizations was observed for an Ag2O/P2O5 ratio of 1, explained by a competition process between Al2O3 and AgI in the glassy network. DSC analyses further revealed the correlation between glass structure modifications and thermal properties. Results show that Tg decreases upon AgI incorporation but increases with Al2O3 content. Static eaching tests in pure water (MCC1-like test) conducted at 50�C showed the formation of a thin layer containing ?-Agi and the initial rate was estimated to be 6 g.m-2.d-1.

Incorporation of iodine in phosphate-based glasses

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.