The potential use of swelling clays for backfilling and sealing of underground repositories: the case of the Boom clay

Geert Volckaert, Frank Vandervoort

Research outputpeer-review


In Belgium the SCK/CEN is studying the geological disposal of high level radioactive waste in the Boom clay formation. In such an argillaceous repository, the backfilling and sealing features will be multiple: boreholes, shafts, access drifts, disposal galleries or holes and dams. A preliminary selection study screening industrial materials has been performed based on the following criteria: at least as good thermal and hydraulic properties as the in situ Boom clay, sufficient volumetric swelling and swelling pressure, proven geochemical compatibility and stability. This study has shown that swelling clays are the most promising materials. Because of its evident geochemical compatibility and its easy availability, it is a logic choice to study the re-use of the excavated clay. The hydraulic, thermal and geochemical retention and swelling properties of the Boom clay were studied and the results are compared to those of bentonites. The main results of this study are: a hydraulic conductivity as low as 10-13 m/s can be reached which is one order of magnitude lower than that of the in situ Boom clay but is one order of magnitude higher than those of bentonite; the volumetric swelling of the Boom clay is rather limited but a swelling pressure of about 4 MPa can be obtained which is about a factor five lower than for bentonites but also corresponds to the in situ lithostatic pressure; the radionuclide retention properties of the in situ Boom clay are at least as good as those of dense bentonites and are for some nuclides even better; steam drastically reduces the volumetric swelling of bentonites which also leads to a higher hydraulic conductivity. The swelling properties of the Boom clay are also to be affected by steam, but the effect is less dramatic. In particular, its low hydraulic conductivity seems to be conserved. (author). 14 refs, 4 figs, 6 tabs
Original languageEnglish
Title of host publicationUse of inorganic sorbents for treatment of liquid radioactive waste and backfill of underground repositories
Subtitle of host publicationProceedings of a final Research Co-ordination Meeting held in Rez, Czechoslovakia, 4-8 November 1991
PublisherSCK CEN
Number of pages13
StatePublished - Nov 1992
Event1991 - IAEA final research Co-ordination meeting - Rez, Czechoslovakia
Duration: 4 Nov 19918 Nov 1991

Publication series

NameIAEA Reports
PublisherIAEA - International Atomic Energy Agency
ISSN (Print)1011-4289


Conference1991 - IAEA final research Co-ordination meeting
Country/TerritoryCzech Republic
CityRez, Czechoslovakia

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