Oxidation front and oxygen transfer in the fractured zone surrounding the Meuse/Haute-Marne URL drifts in the Callovian–Oxfordian argillaceous rock
Published:January 01, 2014
Agnès Vinsot, François Leveau, Alain Bouchet, Apolline Arnould, 2014. "Oxidation front and oxygen transfer in the fractured zone surrounding the Meuse/Haute-Marne URL drifts in the Callovian–Oxfordian argillaceous rock", Clays in Natural and Engineered Barriers for Radioactive Waste Confinement, S. Norris, J. Bruno, M. Cathelineau, P. Delage, C. Fairhurst, E. C. Gaucher, E. H. Höhn, A. Kalinichev, P. Lalieux, P. Sellin
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Deep argillaceous rocks are reducing environments. When exposed to air, reduced minerals of these rocks react with oxygen, modifying the surrounding chemical conditions. Thus, oxidation is an issue in studies about the confining properties of such rocks in the framework of geological disposal projects for radioactive waste. Previous studies in several underground research laboratories (URLs) in argillaceous rocks have shown that oxidation reactions mainly occurred in the excavation-induced fracture network surrounding the drifts. In the Callovian–Oxfordian argillaceous rock, at −490 m in drifts from the Meuse/Haute-Marne URL, oxidized features were systematically looked for in 115 borehole cores. The concerned drifts were of various ages, from a few days to 6.5 years. After 5 months, oxidized features were encountered in numerous excavation-induced extensional fractures. In excavation-induced shear fractures, oxidized features were observed in a few borehole cores after 2 years, and they became frequent after 6 years. In all cases, the oxidized features observed were found on the fracture walls or were connected to them, and were less than 1.8 m from the drift walls. These observations about the oxidation front and its evolution over time provide insights regarding the properties of excavation-induced fractures with respect to oxygen transfer.
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Clays in Natural and Engineered Barriers for Radioactive Waste Confinement
This Special Publication contains 43 scientific studies presented at the 5th conference on ‘Clays in natural and engineered barriers for radioactive waste confinement’ held in Montpellier, France in 2012. The conference and this resulting volume cover all the aspects of clay characterization and behaviour considered at various temporal and spatial scales relevant to the confinement of radionuclides in clay, from basic phenomenological process descriptions to the global understanding of performance and safety at repository and geological scales. Special emphasis has been given to the modelling of processes occurring at the mineralogical level within the clay barriers.
The papers in this Special Publication consider research into argillaceous media under the following topic areas: large-scale geological characterization; clay-based concept/large-scale experiments; hydrodynamical modelling; geochemistry; geomechanics; mass transfer/gas transfer; mass transfer mechanisms.
The collection of different topics presented in this Special Publication demonstrates the diversity of geological repository research.