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Changes in hydraulic conductivity of sand-bentonite mixtures accompanied by alkaline alteration†

Published online by Cambridge University Press:  09 July 2018

T. Yamaguchi ,
T. Sawaguchi ,
M. Tsukada ,
M. Kadowaki  and
T. Tanaka
T. Yamaguchi*
Affiliation:
Waste Safety Research Group, Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
T. Sawaguchi
Affiliation:
Waste Safety Research Group, Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
M. Tsukada
Affiliation:
Waste Safety Research Group, Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
M. Kadowaki
Affiliation:
Waste Safety Research Group, Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
T. Tanaka
Affiliation:
Waste Safety Research Group, Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
*
*E-mail: [email protected]
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Abstract

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Highly alkaline environments induced by cementitious materials in radioactive waste repositories are likely to alter montmorillonite, the main constituent of bentonite buffer materials, and are likely to cause the physical and/or chemical properties of the buffer materials to deteriorate. The deterioration may cause variation in hydraulic conductivity of the buffer. However, empirical data on the variation of hydraulic conductivity are scarce, mainly because the alteration of compacted buffer materials, sand-bentonite mixtures, is extremely slow. In this study, laboratory experiments were performed to observe changes in hydraulic conductivity of sand-bentonite mixtures, accompanied by their alkaline alteration, using NaOH-based solutions at 80–90°C. Series-1 multi-step alteration/water conduction experiments resulted in an increase in the hydraulic conductivity by one order of magnitude over a 200 day period. Series-2 single step alteration/water conduction experiments revealed a decrease in the montmorillonite contents with time and a resulting increase in the hydraulic conductivity by 30 times over the 67 day period. Series-3 simultaneous alteration/water conduction experiment also demonstrated an increase in the hydraulic conductivity by 30 times over the 150 day period. The results proved that the alkaline alteration of the bentonite buffer can increase the hydraulic conductivity. The data obtained in this study are useful for verification of the code that will be used for assessing the alteration.

Keywords

alterationbentoniteradioactive waste disposalhydraulic conductivitysimulation
Type
Research Article
Information
Clay Minerals , Volume 48 , Issue 2 , May 2013 , pp. 403 - 410
Creative Commons
Creative Common License - CCCreative Common License - BY
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.
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2013

Footnotes

†

This research was funded by the Secretariat of Nuclear Regulation Authority, Nuclear Regulation Authority, Japan.

References

Amaya, T., Shimojo, M., Fujihara, H. & Yokoyama, K. (1999) Reaction of montmorillonite in alkaline solution at 60°C, 90°C, 120°C and 180°C. Material Research Society Symposium Proceedings, 556, 655–662.10.1557/PROC-556-655CrossRefGoogle Scholar
Cuisinier, O., Masrouri, F., Pelletier, M., Villieras, F. & Mosser-Ruck R. (2008) Microstructure of a compacted soil submitted to an alkaline plume. Applied Clay Science, 40, 159–170.10.1016/j.clay.2007.07.005CrossRefGoogle Scholar
Johnston, R.M. & Miller, H.G. (1985) Hydrothermal Stability of Bentonite-based Buffer Materials. Atomic Energy of Canada Limited AECL-8376.Google Scholar
Lee, S.L. & Sinha, A.N. (2001) Bentonite:kaolinite clay liner. Geosynthetics International, 8, 113–133.Google Scholar
Nakayama, S., Sakamoto, Y., Yamaguchi, T., Akai, M., Tanaka, T., Sato, T. & Iida, Y. (2004) Dissolution of montmorillonite in compacted bentonite by highly alkaline aqueous solutions and diffusivity of hydroxide ions. Applied Clay Science, 27, 53–65.10.1016/j.clay.2003.12.023CrossRefGoogle Scholar
Radioactive Waste Management Funding and Research Center (2002) High-temperature column tests. Pp. II-140–II-154 in: Verification Test on Advanced Radioactive Waste Disposal Systems (in Japanese).Google Scholar
Ruhl, J. L. & Daniel, D. E. (1997) Geosynthetic clay liners permeated with chemical solutions and leachates. Journal of Geotechnical and Geoenvironmental Engineering, 123, 369–381.10.1061/(ASCE)1090-0241(1997)123:4(369)CrossRefGoogle Scholar
Yamaguchi, T., Sakamoto, Y., Akai, M., Takazawa, M., Iida, Y., Tanaka, T. & Nakayama, S. (2007) Experimental and modeling study on long-term alteration of compacted bentonite with alkaline groundwater. Physics and Chemistry of the Earth, 32, 298–310.10.1016/j.pce.2005.10.003CrossRefGoogle Scholar
Yamaguchi, T., Yamada, F., Negishi, K., Hoshino, S., Mukai, M., Tanaka, T. & Nakayama, S. (2008) Development and verification of a reactive transport model for long-term alteration of bentonite-cementseawater systems. Physics and Chemistry of the Earth, 33, S285–S294.Google Scholar
Yokoyama, S. & Nakamura, K. (2010) Alteration behavior of bentonite barrier of radioactive waste disposal by alkaline solutions – part 1. Permeability change of compacted bentonite immersed in alkaline solutions. CRIEPI Report No. N09015, Civil Engineering Research Laboratory, Central Research Institute of Electric Power Industry, Abiko, Chiba, Japan (in Japanese).Google Scholar
Yokoyama, S., Nakamura, K., Tanaka, Y. & Hironaga, M. (2011) Alteration behavior of bentonite barrier of radioactive waste disposal by alkaline solutions – part 2. Effect of type of alkaline solution on permeability of compacted bentonite-sand mixture. CRIEPI Report No. N10037, Civil Engineering Research Laboratory, Central Research Institute of Electric Power Industry, Abiko, Chiba, Japan (in Japanese).Google Scholar