Microbial studies in the Canadian nuclear fuel waste management program

Abstract

Atomic Energy of Canada Limited (AECL) has developed a concept for permanent geological disposal of used nuclear fuel in Canada. This concept, based on a multibarrier system, would involve disposal of nuclear fuel waste in titanium or copper containers, surrounded by compacted clay-based buffer and backfill materials, in a vault 500-1000 m deep in granitic rock of the Canadian Shield. Subsurface environments will not be sterile and an experimental program was initiated in 1991 by AECL to address and quantify the potential effects of microbial action on the integrity of the disposal vault. This microbial program focuses on answering specific questions in areas such as the survival of bacteria in compacted clay-based buffer materials under relevant radiation, temperature and desiccation conditions; mobility of microbes in compacted buffer materials; the potential for microbially influenced corrosion of containers; microbial gas production in backfill material; introduction of nutrients as a result of vault excavation and operation; the presence and activity of microbes in deep granitic groundwaters; and the effects of biofilms on radionuclide migration in the geosphere. This paper summarizes the results to date from the research activities at AECL.

Bacterial Diversity in Bentonites, Engineered Barrier for Deep Geological Disposal of Radioactive Wastes

“…Sporulation is a common ability within the Firmicutes [62], which could make them more resistant against extraction of DNA. The biogeochemical processes of microorganisms, either indigenous to the repository´s host rock or introduced during the construction of a repository [10,63], may affect the safety of this long-term deep geological disposal system. Microbial processes can affect the geochemistry of clays and also the mobility and transport of radionuclides from the repository to the geosphere.…”

Microbial communities in bentonite formations and their interactions with uranium

“…The safety of this long-term geological disposal could be compromised by physical and chemical factors, and also by the biogeochemical activity of either indigenous to the repositorý s host rock or introduced during the construction of a repository (Meleshyn, 2011;Stroes-Gascoyne and West, 1997). Microbial processes can affect the geochemistry of clays through three different http://dx.doi.org/10.1016/j.apgeochem.2014.06.022 0883-2927/Ó 2014 Elsevier Ltd. All rights reserved.…”

Fifteen years of microbiological investigation in Opalinus Clay at the Mont Terri rock laboratory (Switzerland)

“…On the one hand, clay deposits are being considered as a potential host rock for DGRs in several countries because of the advantageous physical and hydrogeochemical properties of such deposits. On the other hand, bentonite-based barriers and seals are essential components of many DGR designs for a variety of host rocks where they would fulfil multiple specific roles, such as hydraulic, mechanical, thermal, and chemical protection of the containers and ensuring a diffusion-controlled hydrologic environment (e.g., Stroes-Gascoyne and West 1997).…”