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Apport des verres basaltiques à la validation du modèle GRAAL sur le très long terme

Thomas Ducasse 1
1 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 : This thesis adapts the GRAAL model, initially dedicated to the prediction of the long-term behavior of nuclear glasses, to basaltic glasses.This thesis intends to validate the relevance of the founding hypotheses of the GRAAL model as well as to assess its robustness. To achieve this, two lines of research were carried out simultaneously. The first was to re-parameterize the GRAAL model for basaltic glass compositions. To describe the amorphous layer formed during glass alteration, simple basaltic glasses were leached at 90 ° C and various pH (7, 8.5 and 10). Strong analogies observed on the behavior of the elements allowed to preserve a part of the parameterization of the GRAAL model. Experiments have also been conducted to improve the understanding of the mechanisms of basaltic glasses alteration in silica saturated conditions. It is shown that alteration of the basaltic glass is not limited by a diffusive mechanism like nuclear glass, but by a very slow hydrolysis of the vitreous network sustained by the precipitation of secondary phases. Thus, a modification of the kinetic law of the model controlling the dissolution of the glass was carried out.The model, then, accurately accounts for the alteration of basaltic glass in slightly alkaline conditions, thus reinforcing the confidence that can be given to the model on the predictions related to nuclear glasses.
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https://tel.archives-ouvertes.fr/tel-01914304
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Submitted on : Tuesday, November 6, 2018 - 6:42:05 PM
Last modification on : Tuesday, September 8, 2020 - 5:24:45 AM
Long-term archiving on: : Thursday, February 7, 2019 - 5:05:39 PM

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Thomas Ducasse. Apport des verres basaltiques à la validation du modèle GRAAL sur le très long terme. Science des matériaux [cond-mat.mtrl-sci]. Université Montpellier, 2017. Français. ⟨NNT : 2017MONTS040⟩. ⟨tel-01914304⟩

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