Modeling the Long‐term Stability of Multi‐barrier Systems for Nuclear Waste Disposal in Geological Clay Formations

Abstract

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Mössbauer spectrometry insights into the redox reactivity of Fe-bearing phases in the environment

“…With regard to claystone-rich geological formations, such as claystone and bentonite, the scientific community has seen over the last two decades a remarkable surge of interest for the properties of clays, as they apply to a variety of natural and engineered settings. Clayey materials play a key role in long-term storage of nuclear wastes in geologic repositories [44], where reduced redox conditions are responsible for the expected low solubility, and hence mobility, of a wide range of radionuclides including uranium (U), selenium (Se), and plutonium (Pu) [45]. In claystones, such as the Callovian-Oxfordian argillite (COx) found at Bure (France), the Boom clay at Mol (Belgium), and the Opalinus Clay (Opa) at Mont-Terri or at Benken (Switzerland), in situ reducing conditions are reflected by the presence of Pyrite, which is also the main Fe II -bearing phase in most of these claystones, but also by the presence of (Fe II and Fe III ) clay minerals as well as Fe II -carbonate minerals [46][47][48].…”

RTM for Waste Repositories

“…While the release of ferric ions causes the precipitation of iron (oxy)hydroxides, carbonates will play a major role in the buffering of proton release concomitantly affecting the population of the clay exchanger. At the laboratory scale, flow-through oxidation experiments conducted on COx tailings can be reproduced using RTM studies (Claret et al 2018a). Recently an in situ experiment (OXITRAN) has been set up in the Tournemire underground research laboratory in which the time evolution of oxygen partial pressure in a measurement chamber isolated from the atmosphere has been recorded (Barnichon et al 2018).…”

Impact of Uniaxial Mechanical Perturbation on Structural Properties and Smectite Porosity Features: Ion Exchanger Efficiency and Adsorption Performance Fate

“…e use of compacted clays, as part of the multibarrier concept, ensures the previously cited requirements [7,8]. Indeed, the most used materials in land ll disposal are compacted clay liner (CCL) and geosynthetic clay liner (GCL).…”

“…Indeed, the most used materials in land ll disposal are compacted clay liner (CCL) and geosynthetic clay liner (GCL). e main reason for using such materials is their intrinsic properties, such as the large speci c surface areas (SSA), the low permeability, the cation exchange capacity (CEC), the high adsorption ability, and the low hydraulic conductivity [6][7][8][9][10][11]. Compacted clay liners are less expensive, and it has good attenuation capacity.…”