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Microbial responses to elevated temperature: Evaluating bentonite mineralogy and copper canister corrosion within the long-term stability of deep geological repositories of nuclear waste

Marcos F. Martinez-Moreno, Cristina Povedano-Priego, Adam Mumford, Mar Morales-Hidalgo, Kristel Mijnendonckx, Fadwa Jroundi, Jesus Ojeda Ledo Orcid Logo, Mohamed L. Merroun

Science of The Total Environment, Volume: 915, Start page: 170149

Swansea University Authors: Adam Mumford, Jesus Ojeda Ledo Orcid Logo

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Abstract

Deep Geological Repositories (DGRs) consist of radioactive waste contained in corrosion-resistant canisters, surrounded by compacted bentonite clay, and buried few hundred meters in a stable geological formation. The effects of bentonite microbial communities on the long-term stability of the reposi...

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Published in: Science of The Total Environment
ISSN: 0048-9697
Published: Elsevier BV 2024
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa65446
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Abstract: Deep Geological Repositories (DGRs) consist of radioactive waste contained in corrosion-resistant canisters, surrounded by compacted bentonite clay, and buried few hundred meters in a stable geological formation. The effects of bentonite microbial communities on the long-term stability of the repository should be assessed. This study explores the impact of harsh conditions (60 ºC, highly-compacted bentonite, low water activity), and acetate:lactate:sulfate addition, on the evolution of microbial communities, and their effect on the bentonite mineralogy, and corrosion of copper material under anoxic conditions. No bentonite illitization was observed in the treatments, confirming its mineralogical stability as an effective barrier for future DGR. Anoxic incubation at 60 ºC reduced the microbial diversity, with Pseudomonas as the dominant genus. Culture-dependent methods showed survival and viability at 60 ºC of moderate-thermophilic aerobic bacterial isolates (e.g., Aeribacillus). Despite the low presence of sulfate-reducing bacteria in the bentonite blocks, we proved their survival at 30 ºC but not at 60 ºC. Copper disk´s surface remained visually unaltered. However, in the acetate:lactate:sulfate-treated samples, sulfide/sulfate signals were detected, along with microbial-related compounds. These findings offer new insights into the impact of high temperatures (60ºC) on the biogeochemical processes at the compacted bentonite/Cu canister interface post-repository closure.
Keywords: Nuclear repository, compacted bentonite, high temperature, microbial diversity, sulfate-reducing bacteria, copper corrosion
College: Faculty of Science and Engineering
Funders: The present work was supported by the grant RTI2018–101548-B-I00 “ERDF A way of making Europe” to MLM from the “Ministerio de Ciencia, Innovación y Universidades” (Spanish Government). The project leading to this application has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 847593 to MLM. ADM acknowledges funding from the UK Engineering and Physical Sciences Research Council (EPSRC) DTP scholarship (project reference: 2748843). MFM-M acknowledges the Federation of European Microbiological Societies (FEMS) for the award of a Research and Training Grant (FEMS-GO-2021-077) at the SCK CEN (Belgium).
Start Page: 170149