Corrosion of the International Simple Glass under acidic to hyperalkaline conditions

Assessment of glass dissolution kinetics, under disposal relevant temperature and pH environments, is required to credibly estimate radionuclide release rates from vitrified radioactive waste. Leaching of the International Simple Glass (ISG) under acidic to hyperalkaline conditions was examined. Forward rate measurements have been obtained using the dynamic leaching SPFT protocol and rate parameters for B, Na and Si in the basic regime; errors in rates predicted using these parameters at high pH and temperature are significant because the fitting uses logarithmic data. Longer term behaviour under hyperalkaline conditions, representative of some disposal environments, was investigated using the PCT and MCC-1 static leaching protocols with Ca(OH)2 solutions for up to 120 days (PCT) and 720 days (MCC-1). In hyperalkaline conditions dissolution was incongruent for all elements and the presence of alternating zirconia-rich and zirconia-poor alteration layers was observed on all leached monoliths, indicating the occurrence of a self-organisation phenomenon during leaching

Data for: Influence of zeolite precipitation on borosilicate glass alteration under hyperalkaline conditions

Elemental concentrations and measured pH for all the experiments. Details of phyllosilicates on the glass grain surface (SEM image)

Effects of Al:Si and (Al+Na):Si Ratios on the Static Corrosion of Sodium-Boroaluminosilicate Glasses

International audienceUnderstanding alteration mechanisms of borosilicate glasses in aqueous media is essential to nuclear waste performance assessments to ensure radioisotopes are contained for extended durations. Aluminum is typically added to glass compositions to reduce the extent of alteration. However, previous work on 7-day durability tests has suggested that Al has a non-linear relationship with extent of alteration. The effects of Al:Si and (Al+Na):Si substitutions on glass durability were evaluated using series of glasses based on the International Simple Glass corroded in static conditions up to 13 months in deionized water at 90 °C. The alteration behavior was determined by measurement of element release in solution. The ⁓7-day alteration trends across the series were consistent with predicted trends. The 13 month results indicated overall alteration decreased as Al:Si ratios increased and was unaffected by changes in (Al+Na):Si except for the glass with the highest (Al+Na):Si ratio (ISG-A23N), which completely altered within 14 days. Frequent sampling and in-situ Raman measurements revealed ISG-A23N experienced several distinguishable alteration rate regimes within 7 days, forming a ⁓100 µm alteration layer and a NaSiAlO4 zeolite