Geochemical properties of bentonite pore water in high-level-waste repository condition
- Tokai Univ., Hiratsuka (Japan). Nuclear Engineering Dept.
- Central Research Inst. of Electric Power Industry, Komae, Tokyo (Japan). Radiochemistry Group
The chemically favorable nature of bentonite pore water is clarified by the PHREEQE geochemical simulation code. Bentonite is viewed as a candidate buffer material for a high-level-waste repository, and bentonite`s pore water chemistry is expected to result in a reduced Eh and weak alkaline pH region. Pyrite (Fe{sub 2}S), initially contained in bentonite, alters to magnetite (Fe{sub 3}O{sub 4}), and this redox couple reaction controls the oxidation reduction potential. A mild alkaline pH condition is produced mainly by an ion exchange reaction between the sodium in bentonite and the protons in the solution. A geochemical simulation of the ion exchange reactions and the pyrite-magnetite alteration suggests that a favorable chemical condition would exist during the waste glass dissolution and indicates that the Ph and the Eh values are {minus}7.5 to {minus}9.4 and {minus}450 to {minus}320 mV, respectively, when the granitic groundwater intrudes into the compacted bentonite in the repository.
- OSTI ID:
- 477292
- Journal Information:
- Nuclear Technology, Vol. 118, Issue 1; Other Information: PBD: Apr 1997
- Country of Publication:
- United States
- Language:
- English
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