The aim of these measurements is to study how a silica saturated solution influences leaching from a HLW glass matrix. Cylindrical samples of I117 borosilicate glasses were suspended in polycarbonate vials containing a SiO2 saturated solution and leached at temperature of 50 or 80°C for different times (from 1/2 to 28 days). Mass loss, X-ray photoelectron spectroscopy (XPS) and nuclear reaction techniques were applied for post leaching tests on the glass samples.
Analysis of boron and sodium released from the glass were performed in the leachate. Sodium and boron release followed a square root time dependence at all the observed leaching times.
XPS measurements revealed a surface increase of silicon content with respect to unleached samples, with aluminium showing the same behaviour as silicon. The presence of the layer enriched in silicon and aluminium does not stop the release of sodium and boron, whereas the mass loss does slow down because of the formation of aluminio-silicate compounds.