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Modelling Transport of 14 C-Labelled Natural Organic Matter (NOM) in Boom Clay

Published online by Cambridge University Press:  01 February 2011

Alice Ionescu ,
Norbert Maes  and
Dirk Mallants
Alice Ionescu
Affiliation:
Agency for Radwaste Management (ANDRAD), Str. Campului 1, Mioveni 115400, Romania
Norbert Maes
Affiliation:
Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, 2400 Mol, Belgium
Dirk Mallants
Affiliation:
Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, 2400 Mol, Belgium
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Abstract

In Belgium, the Boom Clay formation is considered to be the reference formation for HLW disposal R&D. Assessments to date have shown that the host clay layer is a very efficient barrier for the containment of the disposed radionuclides. Due to absence of significant water movement), diffusion - the dominant transport mechanism, combined with generally high retardation of radionuclides, leads to extremely slow radionuclide migration. However, trivalent lanthanides and actinides form easily complexes with the fulvic and humic acids which occur in Boom Clay and in its interstitial water. Colloidal transport may possibly result in enhanced radionuclide mobility, therefore the mechanisms of colloidal transport must be better understood. Numerical modeling of colloidal facilitated radionuclide transport is regarded an important means for evaluating its importance for long-term safety.

The paper presents results from modeling experimental data obtained in the framework of the EC TRANCOM-II project, and addresses the migration behavior of relevant radionuclides in a reducing clay environment, with special emphasis on the role of the Natural Organic Matter (NOM) [1]. Percolation type experiments, using stable 14C-labelled NOM, have been interpreted by means of the numerical code HYDRUS-1D [2]. Tracer solution collected at regular intervals was used for inverse modeling with the HYDRUS-1D numerical code to identify the most likely migration processes and the associated parameters. Typical colloid transport submodels tested included kinetically controlled attachment/detachment and kinetically controlled straining and liberation.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1107: Scientific Basis for Nuclear Waste Management XXXI , 2008 , 629
Copyright
Copyright © Materials Research Society 2008

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References

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