Silicate glass alteration enhanced by iron: origin and long-term implications

Area of Science:

• Materials Science
• Geochemistry
• Nuclear Engineering

Background:

• Silicate glasses serve as containment matrices for nuclear waste in deep geological disposal.
• Understanding glass-iron interactions is crucial for predicting radionuclide release into the geosphere.

Purpose of the Study:

• To investigate the dissolution mechanisms of silicate glasses in contact with iron.
• To compare glass-iron interactions in short-term nuclear and long-term archeological systems.

Main Methods:

• Multiscale and multianalytical approach.
• Scanning Transmission X-ray Microscopy (STXM) under synchrotron radiation.

Main Results:

• Remarkable similarities observed between short-term nuclear and long-term archeological glass-iron interfaces.
• Iron migration within a porous gel layer was identified.
• Precipitation of iron-silicates locally increases short-term glass alteration, persisting long-term.

Conclusions:

• Iron-silicate formation is a key mechanism in glass alteration at the glass-iron interface.
• Findings enhance the understanding of long-term glass durability in geological disposal environments.
• This research aids in predicting radionuclide release from nuclear waste containment.