Potential influence of microorganisms on the corrosion of the carbon steel in the French high‐level long‐lived nuclear waste disposal context at 50°C

Abstract

In this study, short‐term experiments were carried out to assess the microbially influenced corrosion (MIC) risk in the context of the French high‐level radioactive waste disposal CIGEO (Centre Industriel de Stockage Géologique). The exposures were carried out in different representative media, including the presence of different cement‐grout mixtures as filling material. Nonsterile and biotic conditions with nutrients were considered. For biotic conditions, specific preparations of microbial inoculum were carried out from samples collected at ANDRA's Underground Research Laboratory and microorganisms from the library. Corrosion kinetics were determined using both traditional coupons and completed with real‐time electrical resistance sensors. Microbiological characterizations consisted of cultural approach, quantitative polymerase chain reaction, and next‐generation sequencing. The obtained results show no significant MIC, but a reduced risk was observed using more alkaline filling materials.

Potential influence of microorganisms on the corrosion of carbon steel in the French high‐level long‐lived radioactive waste disposal context at 80°C

“…The nominal composition is given elsewhere. [ 2 ] The Fe 25 µm sensors were monitored using a multichannel voltmeter (Fluke Hydra 2638A) and a direct current power supply. The Fe 250 µm sensors were monitored with an Aircorr device from nke Instrumentation.…”

“…Schematic view of the four media tested—for each media: one nonsterile and two biotic conditions. [ 2 ] ER, electrical resistance; MREA, Matériau de Remplissage de l'Espace Annulaire. [Color figure can be viewed at wileyonlinelibrary.com]…”

“…The composition and indicative pH of the three MREA are detailed elsewhere. [ 2 ] These different mixtures and the preparation method are identical to the previous work at 50°C. [ 2 ] The PW was injected into the cell 15–30 min after the MREA casting.…”

“…The current concept relies on a multibarrier concept composed of two main elements in carbon steel (CS): an overpack and a microtunnel casing. [ 2–4 ]…”

“…The alkalinity provided by the MREA can also favor passivation of steel casing, that is, strongly reduce the corrosion rate. [ 2,4,19 ]…”