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Bentonite reactivity in alkaline solutions: interim results of the Cyprus Natural Analogue Project (CNAP)

  • W. R. Alexander (a1), A. E. Milodowski (a2), A. F. Pitty (a3), S. M. L. Hardie (a4), S. J. Kemp (a2), J. C. Rushton (a2), Andreas Siathas (a5), Avrim Siathas (a5), A. B. Mackenzie (a6), P. Korkeakoski (a7), S. Norris (a8), P. Sellin (a9) and M. Rigas (a10)...

Abstract

Bentonite is one of the more safety-critical components of the engineered barrier system in the disposal concepts developed for many types of radioactive waste. It is used due to its favourable properties (including plasticity, swelling capacity, colloid filtration, low hydraulic conductivity, high retardation of key radionuclides) and its stability in relevant geological environments. However, bentonite is unstable under alkaline conditions and this has driven interest in low-alkali cements (leachate pH of 10–11). To build a robust safety case, it is important to have supporting natural analogue data to confirm understanding of the likely long-term performance of bentonite. In Cyprus, the presence of natural bentonite in close proximity to natural alkaline groundwaters permits the zones of potential bentonite/alkaline water reaction to be studied as an analogy of the potential reaction zones in the repository. Here, the results indicate minimal volumetric reaction of bentonite, with production of a palygorskite secondary phase.

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Copyright

Copyright © The Mineralogical Society of Great Britain and Ireland 2013 This is an Open Access article, distributed under the terms of the Creative Commons Attribution license. (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.

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current address MCM International, Baden-Dättwil, Switzerland

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References

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