Microelectrochemical Study Of Carbon Steel Biocorrosion Mechanism By Shewanella Oneidensis Under The Influence Of H_2 As Electron Donor

摘要

The confinement concept for high level, and intermediary level, of nuclear waste is based on a multi-barrier system. This model consists in different sort of materials such as carbon steel, stainless steel, glass, concrete and clay placed in an underground environment, in order to retain, as long as possible, the radioactivity dissipation. In the disposal, a high level of hydrogen formation is expected, arising from the anoxic corrosion of the metallic containers and also from the radiolysis process. This hydrogen can represent a new energetic source for anaerobic bacterial development. The objective of this study is a better understanding of the influence of local hydrogen formation in the carbon steel biocorrosion process in presence of an Iron Reducing Bacteria (IRB), Shewanella oneidensis. These microorganisms are able to reduce the Iron III from the oxides layers, like magnetite (Fe_3O_4), and, at the same time, they can also use the hydrogen as an electron donor. Local electrochemical techniques were applied in order to locally generate hydrogen in a presence of IRB, where only the corrosion products of carbon steel were used as electrons donor and acceptor. A differential microbial activity was observed according to the hydrogen concentration. Considering the biocorrosion phenomenon as a potential agent of the localised corrosion which can have a direct influence on the durability of the barriers system in a nuclear waste disposal, this work gives relevant data of the kinetics of the biocorrosion process in order to better forecasting project. Acknowledgements: the research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 238579. Project website: www.biocor.eu/ip12 (RSP4).