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Environmental Earth Sciences

, Volume 69, Issue 8, pp 2569–2579 | Cite as

Lab-scale performance of selected expandable clays under HLW repository conditions

  • Jörn Kasbohm
  • Roland Pusch
  • Lan Nguyen-Thanh
  • Thao Hoang-Minh
Original Article

Abstract

Smectite clay has been proposed for embedding canisters with highly radioactive waste in deep repositories because of its isolating capacity. Montmorillonite-rich bentonite is a premier buffer candidate for many national organizations that are responsible for disposal of such waste. Experience from the use of drilling mud at large depths indicates that other smectite clay minerals are more stable chemically and saponite is one of them. The physical properties of smectitic mixed-layer minerals like Friedland clay are known to be less sensitive to high salt contents and such clay may also be a buffer candidate. Montmorillonite-rich MX-80 clay, Greek saponite with a minor amount of palygorskite, and Friedland clay were investigated in hydrothermal tests with dense samples confined in oedometers with 95 °C temperature at one end, which was made of copper, and 35 °C at the other, for 8 weeks. A 1 % CaCl2 solution was circulated through a filter at the cold end. At the end of the tests, the samples were sliced into three parts, which were tested with respect to expandability, hydraulic conductivity, and chemical composition. The tests showed that while the saponite was hardly changed at all and did not take up any copper, MX-80 underwent substantial changes in physical performance and adsorbed significant amounts of copper. The Friedland clay sample was intermediate in both respects.

Keywords

Smectite alteration THMC-framework Mineralogy Hydraulic conductivity Swelling pressure 

Notes

Acknowledgments

Support to complete the manuscript from the National Foundation for Science and Technology Development, Vietnam (project code 105.02.54.09) is gratefully acknowledged.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Jörn Kasbohm
    • 1
    • 2
  • Roland Pusch
    • 3
  • Lan Nguyen-Thanh
    • 1
    • 2
  • Thao Hoang-Minh
    • 4
  1. 1.GeoENcon Ltd.GreifswaldGermany
  2. 2.Institute of Geography and GeologyErnst-Moritz-Arndt-University of GreifswaldGreifswaldGermany
  3. 3.Luleå Technical UniversityLuleåSweden
  4. 4.Hanoi University of ScienceVietnam National University, HanoiHanoiVietnam

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