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Effect of Temperature and Bicarbonate Concentration on the Kinetics of UO2(s) Dissolution Under Oxidizing Conditions

Published online by Cambridge University Press:  03 September 2012

J. de Pablo ,
I. Casas ,
J. Giménez ,
M. Molera  and
M. E. Torrero
J. de Pablo
Affiliation:
Department of Chemical Engineering, Universitat Politècnica Catalunya, 08028 Barcelona., Spain
I. Casas
Affiliation:
Department of Chemical Engineering, Universitat Politècnica Catalunya, 08028 Barcelona., Spain
J. Giménez
Affiliation:
Department of Chemical Engineering, Universitat Politècnica Catalunya, 08028 Barcelona., Spain
M. Molera
Affiliation:
Department of Chemical Engineering, Universitat Politècnica Catalunya, 08028 Barcelona., Spain
M. E. Torrero
Affiliation:
Department of Chemical Engineering, Universitat Politècnica Catalunya, 08028 Barcelona., Spain
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Abstract

The dissolution rate of unirradiated UO2 (s) has been studied as a function of hydrogen carbonate concentration at three different temperatures (298.15 K, 313.15 K and 333.15 K) under oxidizing conditions in a continuous flow-through reactor with a thin layer of solid particles (particle size from 100 to 300 μm). From the results of these experiments, two different rate laws have been determined. At high temperature (313.15 K and 333.15 K), we obtained a dissolution rate proportional to hydrogen carbonate concentration while at 298.15 K, the rate almost depends on the square root of the hydrogen carbonate concentration. This indicates a different reaction mechanism depending on temperature which can be related to the oxidation step of the overall process. The apparent activation energy obtained was 41 kJ mo1−1.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 465: Symposium II – Scienfific Basis for Nuclear Waste Management XX , 1996 , 535
Copyright
Copyright © Materials Research Society 1997

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References

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