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Reactivity of nitrate and organic acids at the concrete–bitumen interface of a nuclear waste repository cell

Bertron, Alexandra and Jacquemet, Nicolas and Erable, Benjamin and Sablayrolles, Caroline and Escadeillas, Gilles and Albrecht, Achim Reactivity of nitrate and organic acids at the concrete–bitumen interface of a nuclear waste repository cell. (2014) Nuclear Engineering and Design, vol. 268. pp. 51-57. ISSN 0029-5493

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Official URL: http://dx.doi.org/10.1016/j.nucengdes.2013.11.085

Abstract

This study investigates the fate of nitrate and organic acids at the bitumen–concrete interface within repository cell for long-lived, intermediate-level, radioactive wastes. The interface was simulated by a multiphase system in which cementitious matrices (CEM V cement paste specimens) were exposed to bitumen model leachates consisting of nitrates and acetic acid with and without oxalic acid, chemical compounds likely to be released by bitumen. Leaching experiments were conducted with daily renewal of the solutions in order to accelerate reactions. The concentrations of anions (acetate, oxalate, nitrate, and nitrite) and cations (calcium, potassium) and the pH were monitored over time. Mineralogical changes of the cementitious matrices were analysed by XRD. The results confirmed the stability of nitrates in the abiotic conditions of the experiments. The action of acetic acid on the cementitious matrix was similar to that of ordinary leaching in the absence of organic acids (i.e. carried out with water or strong acids); no specific interaction was detected between acetate and cementitious cations. The reaction of oxalic acid with the cementitious phases led to the precipitation of calcium oxalate salts in the outer layer of the matrix. The concentration of oxalate was reduced by 65% inside the leaching medium.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com/science/article/pii/S0029549313007346
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Agence Nationale pour la Gestion des Déchets Radioactifs - ANDRA (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
Université de Toulouse > Institut National des Sciences Appliquées de Toulouse - INSA (FRANCE)
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS (FRANCE)
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Deposited By: Benjamin ERABLE
Deposited On:24 Feb 2014 11:11

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