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Simulation of Transport of Uranium (VI) Species Through the Bed of Bentonite

Published online by Cambridge University Press:  10 February 2011

K. Ştamberg ,
D. Vopálka ,
J. Škrkal ,
P. Beneš  and
K. Chalupská
K. Ştamberg
Affiliation:
Czech Technical University, Department of Nuclear Chemistry, Břehová 7, 11519 Prague Czech Republic, [email protected]
D. Vopálka
Affiliation:
Czech Technical University, Department of Nuclear Chemistry, Břehová 7, 11519 Prague Czech Republic
J. Škrkal
Affiliation:
Czech Technical University, Department of Nuclear Chemistry, Břehová 7, 11519 Prague Czech Republic
P. Beneš
Affiliation:
Czech Technical University, Department of Nuclear Chemistry, Břehová 7, 11519 Prague Czech Republic
K. Chalupská
Affiliation:
Czech Technical University, Department of Nuclear Chemistry, Břehová 7, 11519 Prague Czech Republic
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Abstract

The transport of six U(VI) species, HCO31− and CO32−, through the bentonite bed was modelled as diffusion in pore water combined with sorption/desorption on the surface of bentonite particles. The studied system consisted of the Czech commercial sodium bentonite SABENYL and synthetic granitic water spiked with 233U(VI), where equilibrium distribution of 233U was experimentally determined at first. The transport was simulated by means of eight dynamic, 1 D- partial differential equations while the equilibrium sorption/desorption was assumed. Three types of surface complexation models, namely the Constant Capacitance Model (CCM), Diffuse Double Layer Model (DLM) and the so-called Chemical Equilibrium Model (CEM), were used for the description of sorption/desorption interaction processes. The characteristic parameters of the individual models were obtained from evaluation of experimental data. The results of the simulation were expressed as path-length dependent concentrations of total U(VI), total carbonates and of individual migration species, as path-length dependent pH and uranium Kd, values at a given time and as time dependent concentrations of the total U(VI) at a given migration distance. It has been found that the transport of U(VI) through the bentonite bed is significantly influenced first of all by the value of pH and by total carbonates concentration. The important length dependent changes of the pH and Kd values were determined.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 506: Symposium – Scientific Basis for Nuclear Waste Management XXI , 1997 , 485
Copyright
Copyright © Materials Research Society 1998

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References

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