Impact of microbial activity on the radioactive waste disposal: long term prediction of biocorrosion processes

• The role of hydrogenotrophic IRB and SRB in biocorrosion phenomena is highlighted.
• IRB use ferric iron from magnetite and dihydrogen as energy sources.
• Mixed redox conditions tend to favour biocorrosion in the presence of SRB.
• Acquisition of kinetic data for long term biocorrosion rate is ongoing.

This study emphasizes different experimental approaches and provides perspectives to apprehend biocorrosion phenomena in the specific disposal environment by investigating microbial activity with regard to the modification of corrosion rate, which in turn can have an impact on the safety of radioactive waste geological disposal.It is found that iron-reducing bacteria are able to use corrosion products such as iron oxides and “dihydrogen” as new energy sources, especially in the disposal environment which contains low amounts of organic matter. Moreover, in the case of sulphate-reducing bacteria, the results show that mixed aerobic and anaerobic conditions are the most hazardous for stainless steel materials, a situation which is likely to occur in the early stage of a geological disposal. Finally, an integrated methodological approach is applied to validate the understanding of the complex processes and to design experiments aiming at the acquisition of kinetic data used in long term predictive modelling of biocorrosion processes.

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