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Experimental Investigation of Aqueous Corrosion of R7T7 Nuclear Glass at 90°C in the Presence of Humic Acids: a Kinetic Approach

Published online by Cambridge University Press:  25 February 2011

S. Gin ,
N. Godon ,
J.P. Mestre ,
E.Y. Vernaz  and
D. Beaufort
S. Gin
Affiliation:
CEA, Rhône Valley Research Center, BP 171, 30207 Bagnols-sur-Cèze, France
N. Godon
Affiliation:
CEA, Rhône Valley Research Center, BP 171, 30207 Bagnols-sur-Cèze, France
J.P. Mestre
Affiliation:
CEA, Rhône Valley Research Center, BP 171, 30207 Bagnols-sur-Cèze, France
E.Y. Vernaz
Affiliation:
CEA, Rhône Valley Research Center, BP 171, 30207 Bagnols-sur-Cèze, France
D. Beaufort
Affiliation:
Université de Poitiers, URA CNRS 721, LPAH, 40 Avenue du Recteur Pineau, 86000 Poitiers, France
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Abstract

The dissolution kinetics of the French “R7T7” nonradioactive LWR reference glass in solutions containing dissolved humic acids were investigated at 90°C during static tests with imposed or free pH. Experiments conducted in highly dilute media, with a glass-surface-area-to-solution-volume (SA/V) ratio of 5 m-1, showed that the glass dissolution surface reaction is catalyzed by humic acids. With higher degrees of reaction progress (SA/V = 100 m-1 and free pH) the humic acids impose pH modifications on the system compared with inorganic media; moreover, they directly or indirectly enhance the dissolution of certain alkali metals and transition elements, forming aqueous complexes with the latter. During experiments with an imposed pH of 8.5 (SA/V = 1300 and 5300 m-1), the humic acids appear to cause increased silica solubility that cannot be accounted for by the formation of silica complexes. A residual corrosion rate in the humic acid media exceeding the rate measured in inorganic media suggests that, in addition to silica, one or more element complexes formed by humic acids may be a kinetically limiting factor. This hypothesis must be confirmed, however, as the quantity of humic acids per unit glass surface area was too small in this experiment to allow unambiguous characterization of the phenomenon.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 333: Symposium V – Scientific Basis for Nuclear Waste Management XVII , 1993 , 565
Copyright
Copyright © Materials Research Society 1994

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References

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