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HLW glass dissolution in the presence of magnesium carbonate: Diffusion cell experiment and coupled modeling of diffusion and geochemical interactions

Matthieu Debure 1, 2 Laurent de Windt 1 Pierre Frugier 2 S. Gin 2
2 LCLT - Laboratoire d'Etudes du Comportement à Long Terme des matériaux de conditionnement
DE2D - Département de recherche sur les technologies pour l'enrichissement, le démantèlement et les déchets : DEN/DE2D
Abstract : The influence of diffusion of reactive species in aqueous solutions on the alteration rate of borosilicate glass of nuclear interest in the presence of magnesium carbonate (hydromagnesite: 4MgCO3 Mg(OH)2- 4H2O) is investigated together with the ability of coupled chemistry/transport models to simulate the processes involved. Diffusion cells in which the solids are separated by an inert stainless steel sintered filter were used to establish parameters for direct comparison with batch experiments in which solids are intimately mixed. The chemistry of the solution and solid phases was monitored over time by various analytical techniques including ICP-AES, XRD, and SEM. The primary mechanism controlling the geochemical evolution of the system remains the consumption of silicon from the glass by precipitation of magnesium silicates. The solution chemistry and the dissolution and precipitation of solid phases are correctly described by 2D modeling with the GRAAL model implemented in the HYTEC reactive transport code. The spatial symmetry of the boron concentrations in both compartments of the cells results from dissolution coupled with simple diffusion, whereas the spatial asymmetry of the silicon and magnesium concentrations is due to strong coupling between dissolution, diffusion, and precipitation of secondary phases. A sensitivity analysis on the modeling of glass alteration shows that the choice of these phases and their thermodynamic constants
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https://hal-mines-paristech.archives-ouvertes.fr/hal-00860964
Contributeur : Laurent de Windt <>
Soumis le : mercredi 11 septembre 2013 - 15:18:46
Dernière modification le : jeudi 24 septembre 2020 - 16:34:08

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Matthieu Debure, Laurent de Windt, Pierre Frugier, S. Gin. HLW glass dissolution in the presence of magnesium carbonate: Diffusion cell experiment and coupled modeling of diffusion and geochemical interactions. Journal of Nuclear Materials, Elsevier, 2013, 443, pp.507-521. ⟨10.1016/j.jnucmat.2013.07.068⟩. ⟨hal-00860964⟩

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