• journal_title：Clays and Clay Minerals
• Contributor：Regine Mosser-Ruck ; Michel Cathelineau ; Damien Guillaume ; Delphine Charpentier ; Davy Rousset ; Odile Barres ; Nicolas Michau
• Publisher：Clay Minerals Society
• Date：2010-
• Format：text/html
• Language：en
• Identifier：10.1346/CCMN.2010.0580212
• journal_abbrev：Clays and Clay Minerals
• issn：0009-8604
• volume：58
• issue：2
• firstpage：280
• section：Articles

In deep geological repositories for high-level nuclear wastes, interactions between steel canisters and clay-rich materials may lead to mineralogical transformations with a loss of the confining properties of the clays. Experiments simulating the conversion of smectite to Fe-rich clay phases in contact with Fe metal have been carried out to evaluate such a possibility by taking into account the effects of a series of critical parameters, including temperature, pH, and Fe/clay (Fe/C) and liquid/clay (L/C) ratios. The mineralogical and chemical transformations observed in these experiments have been compared with data from the literature, and subsequently used to propose a conceptual model for the main mineralogical transformations which can be expected in clay formations surrounding high-level nuclear waste repositories. In the presence of Fe metal and under low oxygen fugacity (<10⁻⁴⁰) the main mineralogical sequences are as follows:

Low temperatures (<150°C) and large L/C and Fe/C ratios seem to favor the crystallization of the serpentine group minerals instead of Fe-rich trioctahedral smectites or chlorites, the latter being favored by higher temperatures. The role of L/C and Fe/C ratios and the competition between them at different temperatures is a crucial point in understanding the transformation of smectite in contact with Fe metal.