Current Development of Geological Disposal Facilities: A Comprehensive Review of Corrosion and Microbially Influenced Corrosion of Nuclear Waste Canisters.

The long-term safety of geological disposal facilities (GDFs) depends in part on the integrity of metallic waste canisters exposed to evolving thermal, geochemical and microbial conditions. Although abiotic corrosion is comparatively well characterised, the significance of microbiologically influenced corrosion (MIC) remains uncertain. This review critically compares carbon steel, stainless steel, copper, and titanium under GDF-relevant conditions, distinguishing chemical MIC (CMIC) from electrical MIC (EMIC) and examining the roles of sulphate-reducing bacteria, biofilms, and extracellular electron transfer. Reported behaviour varies markedly: carbon-steel studies have reported localised attack approaching 1 mm within 12 months, while SRB-associated copper corrosion rates of up to 9.8 μm year-1 have been measured, yet other long-term experiments show little or no detectable microbial acceleration. These contrasts indicate that microbial presence alone is not predictive of corrosion severity; temperature, redox state, groundwater chemistry, bentonite density, nutrient availability, and passive-film stability are critical controls. The distinctive contribution of this review is an integrated, material-to-material assessment linking abiotic corrosion, CMIC and EMIC mechanisms with repository-specific environmental constraints, and current GDF development. It also identifies key uncertainties arising from methodological variability and short-term laboratory testing, supporting priorities for standardised, long-term, and in situ studies.