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Réactivité géomicrobiologique des matériaux et minéraux ferrifères : impact sur la sureté d'un stockage de déchets radioactifs en milieux argileux

Abstract : This thesis sought to describe the dynamic concept of a viable and sustainable microbiological activity under deep geological disposal conditions and to assess its impact on containment properties and storage components. Thus, in this study, a model based on the bacterial ferric reduction was chosen for its sustainability criteria in the system and its ability to alter the materials in storage conditions. The main results of this work demonstrated the capability of the environment to stand the iron-reducing bacterial activity and the conditions of its development in the deep clay environments. The bio-availability of structural Fe (III) in clay minerals and iron oxides produced during the process of metal corrosion was clearly demonstrated. In this system, the corrosion appears to be a positive factor on bacterial activities by producing an energy source, hydrogen. The iron-reducing bacterial activities can lead to a resumption of metallic corrosion through the consumption of iron oxides in the passive film. The direct consequence would be a reduction of the lifetime of metal containers. In the case of ferric clay minerals, the consequences of such an activity are such that they can have an impact on the overall porous structure both in terms of chemical reactivity of the materials or physical behavior of the clayey barrier. One of the most significant results is the crystallization of new clay phases at very low temperatures, below 40°C, highlighting the influence of the anaerobic microbial activity in the mineralogical transformations of clay minerals. Furthermore, these experiments also allowed to visualize, for the first time, a mechanism of bacterial respiration at distance, this increases the field of the availability of essential elements as Fe3+ for bacterial growth in extreme environment. In conclusion, these results clearly showed the impact of the microbiological factor on the reactivity of clay and metal minerals, while relying on control parameters on bacterial activity. The relevance of taking into account these microbiological activities in the case of safety assessments of a repository is then established.
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https://hal.univ-lorraine.fr/tel-01746181
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Loïc Esnault. Réactivité géomicrobiologique des matériaux et minéraux ferrifères : impact sur la sureté d'un stockage de déchets radioactifs en milieux argileux. Sciences de la Terre. Université Henri Poincaré - Nancy 1, 2010. Français. ⟨NNT : 2010NAN10139⟩. ⟨tel-01746181⟩

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