Basic mechanisms of aqueous corrosion of nuclear waste glasses
R7T7 glass solubility was investigated in experiments with monolithic and powdered glass specimens at high SA/V ratios. A silicon concentration limit was obtained at 90 C, and pH-related variations in this limit were determined. Very low corrosion rates were obtained under saturation conditions: from a few thousandths to a few ten-thousandths of the initial rate. The observed rates were not constant, however, but diminished as the SA/V ratio increased. It is, therefore, impossible to define a constant residual corrosion rate as an inherent glass property, or to specify an activation energy. Experiments at higher temperatures (150 and 250 C) also resulted in a constant corrosion rate under near saturation conditions, but this residual rate was a few per cent of the initial rate, indicating that the dissolution reaction affinity was relatively high at these temperatures. Investigation of the radionuclide containment properties in Volvic water confirmed that under oxidising conditions neptunium and technetium are leached at virtually the same rate as the glass matrix, while plutonium and americium mostly remain trapped in the gel layer that develops at the glass surface. Moreover, the leached plutonium is flocculated and quickly fixed in particle form after a few weeks.
Bibliographic Reference: EUR 13605 EN (1991) 91 pp., FS, ECU 8.75
ISBN: ISBN 92-826-2817-5
Record Number: 199111145 / Last updated on: 1994-12-02
Original language: en
Available languages: en