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Dissolution Studies of Soddyite as a Long-Term Analogue of the Oxidative Alteration of the Spent Nuclear Fuel Matrix

Published online by Cambridge University Press:  03 September 2012

I. Pérez ,
I. Casas ,
M. E. Torrero ,
E. Cera ,
L. Duro  and
J. Bruno
I. Pérez
Affiliation:
Polytechnic University of Catalunya, Dept. of Chem. Eng., Avd. Diagonal 647, 08028 Barcelona (Spain)
I. Casas
Affiliation:
Polytechnic University of Catalunya, Dept. of Chem. Eng., Avd. Diagonal 647, 08028 Barcelona (Spain)
M. E. Torrero
Affiliation:
Polytechnic University of Catalunya, Dept. of Chem. Eng., Avd. Diagonal 647, 08028 Barcelona (Spain)
E. Cera
Affiliation:
QuantiSci, Pare Tecnologie del Vallés, 08290 Cerdanyola (Spain)
L. Duro
Affiliation:
QuantiSci, Pare Tecnologie del Vallés, 08290 Cerdanyola (Spain)
J. Bruno
Affiliation:
QuantiSci, Pare Tecnologie del Vallés, 08290 Cerdanyola (Spain)
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Abstract

The thermodynamic and kinetic dissolution properties of a synthetically obtained soddyite have been determined at different bicarbonate concentrations. This uranium-silicate is expected to be a secondary solid phase of the oxidative alteration pathway of uranium dioxide in waters with low phosphate content and, consequently, it is likely to constitute one of the long-term uranium solubility limiting solid phases.

The experimental data obtained at the end of the experiments correspond fairly well to the theoretical model calculated with a log K0S0 of 3.9±0.7.

On the other hand, the general trend of the total uranium in solution measured in the experiments as a function of time has been fitted by using a kinetic equation obtained from the principle of detailed balancing of the dissolution reaction. In addition, the EQ3/6 code has also been used to model the uranium concentrations as a function of time. In both modeling exercises comparable results were obtained. The dissolution rate, normalized to the total surface area used in the experiments as measured with the BET method, gave an average value of 6.8 (±4.4) 10−14 mol cm−2 s−1.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 465: Symposium II – Scienfific Basis for Nuclear Waste Management XX , 1996 , 565
Copyright
Copyright © Materials Research Society 1997

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References

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