Measurements of Eh and pH in Compacted MX-80 Bentonite
- VTT Technical Research Centre of Finland, Otakaari 3A, Espoo, FI-02044 VTT (Finland)
The low-content free water and high swelling pressure in compacted bentonite, planned to be used as a buffer in nuclear waste repositories, create adverse conditions for direct measurements of the chemical conditions. This paper presents laboratory results from online measurements with Eh and pH electrodes in water-saturated compacted MX-80 bentonite. The Eh was measured with Au and Pt wires as electrodes, while the pH was determined with IrOx electrodes. The latter were prepared in accordance with the method by Yao et al. [1]. The measurements were carried out in two types of cells: 'squeezing cells' and 'diffusion cells'. The squeezing cell excludes almost completely all chemical interactions between the sample and the surrounding environment outside the cell. The diffusion cell, on the other hand, contains a sample that stays in contact with an external solution and therefore allows following of the physico-chemical interaction between the sample and the external solution. The measuring electrodes were positioned inside the cell in the compacted bentonite, while the reference electrode was positioned outside the cell. (authors)
- Research Organization:
- Materials Research Society, 506 Keystone Drive, Warrendale, PA, 15086-7573 (United States)
- OSTI ID:
- 21062450
- Resource Relation:
- Conference: Symposium on Scientific Basis for Nuclear Waste Management, Boston - Massachusetts (United States), 27 Nov - 1 Dec 2006; Other Information: Country of input: France; 10 refs; Related Information: In: Proceedings of the symposium on Scientific Basis for Nuclear Waste Management XXX, by Dunn, Darrell [ed. Southwest Research Inst., San Antonio, Texas (United States)]; Poinssot, Christophe [ed. CEA-Saclay, 91191 Gif-sur-Yvette cedex (France)]; Begg, Bruce [ed. Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)], v. 985, 663 pages.
- Country of Publication:
- United States
- Language:
- English
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