Microbial fouling and corrosion of carbon steel in alkaline deep groundwater

Indigenous groundwater microorganisms may induce corrosion of carbon steel in deep geological repositories for hazardous wastes. Understanding the corrosion of the carbon steel materials of low and intermediate radioactive waste in the repository conditions is crucial in order to ensure the safe storage of the spent nuclear fuel. The waste will be in contact with the concrete of the repository silos and storage containers, and eventually with the groundwater surrounding the silos. In this study the corrosion of carbon steel in the repository conditions and the microbial community, consisting of bacteria, archaea and fungi, forming biofilm on the carbon steel samples was studied over a period of 3 years in the groundwater environment with and without the presence of concrete. The microbial communities in the groundwater and biuofilms on the carbon steel surfaces were characterized using high-throughput amplicon sequencing of the 16S rRNA genes of the archaea and bacteria and the ITS1 region of the fungi.