Studying the migration behaviour of selenate in Boom Clay by electromigration

For the disposal of high-level waste (HLW) in a deep geological formation as Boom Clay, safety assessment studies have shown that long lived 79Se is one of the more critical fission products. Therefore, the knowledge of its migration properties (diffusion, retention) through the geological barrier (...

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Bibliographic Details
Published in:	Engineering geology Vol. 77; no. 3; pp. 285 - 293
Main Authors:	Beauwens, Thomas, De Cannière, Pierre, Moors, Hugo, Wang, Lian, Maes, Norbert
Format:	Journal Article Conference Proceeding
Language:	English
Published:	Amsterdam Elsevier B.V 01-03-2005 Elsevier
Subjects:	Applied sciences Boom clay Buildings. Public works Clay (material) Decontamination. Miscellaneous Diffusion coefficients Earth sciences Earth, ocean, space Electromigration Engineering and environment geology. Geothermics Exact sciences and technology Fission products Geotechnics Migration Miscellaneous Pollution Pollution, environment geology Radioactive waste Selenium Soil and sediments pollution Speciation Waste disposal Electromigration Radioactive waste Boom clay Selenium Diffusion coefficients Speciation Clay International conference Electrokinetics Theoretical study Experimental study Soil pollution Result Decontamination Electrodiffusion Diffusion coefficient
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Summary:	For the disposal of high-level waste (HLW) in a deep geological formation as Boom Clay, safety assessment studies have shown that long lived 79Se is one of the more critical fission products. Therefore, the knowledge of its migration properties (diffusion, retention) through the geological barrier (Boom Clay) is of paramount importance. The migration behaviour of selenium strongly depends on its speciation. Under reducing conditions, selenide would be the dominant species and selenium migration would mainly be controlled by the low solubility of Se(−II)-bearing minerals. However Se species are often found in redox disequilibrium and more oxidized species might also coexist. Therefore, the study of selenate migration requires attention, as it might be the most mobile selenium species in the host rock. Electromigration experiments performed with a 75Se-labeled selenate in Boom Clay indicate a high mobility for this species. The apparent diffusion coefficient ( D app) of selenate in Boom Clay is estimated from electromigration experiments performed under different electric fields. Using two independent approaches, the value of D app for selenate is shown to fall in the range from 1.7×10 −11 to 6.2×10 −11 m 2 s −1. Moreover, no reduction of selenate in Boom Clay was observed.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 SourceType-Scholarly Journals-2 ObjectType-Conference Paper-1 SourceType-Conference Papers & Proceedings-1 ObjectType-Article-3
ISSN:	0013-7952 1872-6917
DOI:	10.1016/j.enggeo.2004.07.019