Indigenous bacterial adaptation and survival: Exploring the shifts in highly compacted bentonite over a 5-year long-term study for nuclear repository purposes.

Compacted bentonite is one of the most promising engineered barrier materials used in Deep Geological Repositories (DGR) of high-level radioactive waste encapsulated in metal canisters. Determining bentonite compaction density threshold for bacterial presence and activity has been a long-standing objective, due to their implications for canisters' durability and, therefore, in the safety performance of DGR. This study provided new insights into the effect of dry density (1.

Dual effect of Se(IV) and bentonite microbial community interactions on the corrosion of copper and Se speciation: Implication on repository safety assessment.

The Deep Geological Repository (DGR) design, the internationally safest option for the long-term disposal of high-level radioactive waste (HLW), features metal canisters encased in compacted bentonite clay and embedded deep within a host rock. Despite presenting a hostile environment for microorganisms, DGRs scenarios with favorable microbial-activity conditions must be considered for the safety assessment of this disposal. This study investigated the impact of Se(IV), as a natural analogue of Se present in the HLW, in anoxic microcosms of bentonite slurry spiked with a bacterial consortium and amended with lactate, acetate, and sulfate as electron donors/acceptor.

Comparing the effectiveness of different DNA extraction methods in MX-80 bentonite.

Approaches to DNA extraction play a crucial role in determining the variability of results obtained through 16S rRNA amplicon sequencing. Particularly, clay-rich samples can impede the efficiency of various standard cultivation-independent techniques. We conducted an inter-laboratory comparison study to thoroughly assess the efficacy of two published DNA extraction methods (kit-based and phenol-chloroform-based) specifically designed for bentonite samples.

Microbial influence in Spanish bentonite slurry microcosms: Unveiling a-year long geochemical evolution and early-stage copper corrosion related to nuclear waste repositories.

The deep geological repository (DGR) concept consists of storing radioactive waste in metal canisters, surrounded by compacted bentonite, and placed deeply into a geological formation. Here, bentonite slurry microcosms with copper canisters, inoculated with bacterial consortium and amended with acetate, lactate and sulfate were set up to investigate their geochemical evolution over a year under anoxic conditions. The impact of microbial communities on the corrosion of the copper canisters in an early-stage (45 days) was also assessed.

Long-term tracking of the microbiology of uranium-amended water-saturated bentonite microcosms: A mechanistic characterization of U speciation.

Deep geological repositories (DGRs) stand out as one of the optimal options for managing high-level radioactive waste (HLW) such as uranium (U) in the near future. Here, we provide novel insights into microbial behavior in the DGR bentonite barrier, addressing potential worst-case scenarios such as waste leakage (e.g.