Effect of γ-radiation on radionuclide retention in compacted bentonite

Abstract

Compacted bentonite is proposed as an engineered barrier in many concepts for disposal of high level nuclear waste. After the initial deposition however, the bentonite barrier will inevitably be exposed to ionizing radiation (mainly γ) under anoxic conditions. Because of this, the effects of γ-radiation on the apparent diffusivity values and sorption coefficients in bentonite for Cs + and Co 2+ were tested under different experimental conditions. Radiation induced effects on sorption were in general more noticeable for Co 2+ than for Cs + , which generally showed no significant differences between irradiated and unirradiated clay samples. For Co 2+ however, the sorption to irradiated MX80 was significantly lower than to the unirradiated clay samples regardless of the experimental conditions. This implies that γ-radiation may alter the surface characteristics contributing to surface complexation of Co 2+ . With the experimental conditions used however, the effect of decreasing sorption was not large enough to be reflected on the obtained Da values.

Reaction mechanisms in swelling clays under ionizing radiation: influence of the water amount and of the nature of the clay mineral

“…Despite its environmental signicance, only few studies discuss the behavior under radiation of those complex and conning systems. 5,[12][13][14][15][16][17] Indeed, energy transfer phenomena should be correctly considered as well as pathways of reactive species within the interlayer space of clay minerals that is highly conned, and in which specic effects may be expected. In a previous study, 5 we have focused our attention on natural montmorillonites of Camp-Berteau (Marocco).…”

An Overview of Interfacial Radiation Chemistry in Nuclear Technology

“…In recent years, the effects of γ‐irradiation on the colloidal stability of bentonite suspensions,52 the cation adsorption and retention on bentonite,53 and the Fe II /Fe III ratio54 have been studied experimentally. The last property also influences the redox reactivity of the material.…”

Investigation of Reactive Transport and Coupled THMC Processes in the EBS

“…The diffusion of water and ions in water-saturated compacted clay barriers has, therefore, been extensively characterized, though mostly at ambient temperatures (Molera and Eriksen, 2002;Molera et al, 2003;Nakashima, 2003;Wang et al, 2005;Melkior et al, 2009;Tachi et al, 2010;Glaus et al, 2011;Tanaka et al, 2011;Holmboe et al, 2011).…”