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Volatility mechanisms of borosilicate glasses and molten glasses of nuclear interest structural effects; Mecanismes de volatilite des verres et des fontes borosilicates d'interet nucleaire influence de la structure

Abstract

This work is devoted to the study of the mechanisms which control the volatility of the reference glass used for the confinement of radioactive waste. It was conducted on simplified compositions, in the SiO{sub 2}-B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-αNa{sub 2}O-(1-alpha)Li{sub 2}O-CaO system.The structural approach carried out by NMR, from room temperature up to 1500 °C, shows a strong increase in the mobility of alkalis above Tg. A rapid exchange between B{sup III} and B{sup IV} sites near 700 °C, and the change of coordination number B{sup IV} - B{sup III} near 1100 °C, also seem to take place. The analysis of the vapor phase, carried out by High Temperature Mass Spectrometry coupled to Knudsen cells, reveals the presence between 780 °C and 830 °C of NaBO{sub 2}(g), LiBO{sub 2}(g) and Na{sub 2}(BO{sub 2})2(g). The calculation of the partial pressure of each species shows that the total pressure of simplified glasses is dominated by the contribution of sodium. To study the volatility of glasses at higher temperature, equipment using the Transpiration method was used. The analysis of the deposits indicate the presence at 1060 °C of the species quoted previously. The vaporization rate and the vapor density were determined for each  More>>
Authors:
Publication Date:
Apr 23, 1998
Product Type:
Thesis/Dissertation
Report Number:
FRCEA-TH-739
Reference Number:
EDB-00:107468
Resource Relation:
Other Information: 122 refs.; Available from the INIS Liaison Officer for France, see the INIS website for current contact and E-mail addresses; This record replaces 31014378; These Physique et Chimie des Materiaux
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; BOROSILICATE GLASS; CESIUM; KNUDSEN FLOW; LITHIUM; MASS SPECTROSCOPY; NUCLEAR MAGNETIC RESONANCE; RADIOACTIVE WASTES; SODIUM; THERMODYNAMIC ACTIVITY; THERMODYNAMIC PROPERTIES; VITRIFICATION; VOLATILITY
OSTI ID:
20049650
Research Organizations:
CEA Saclay, 91 - Gif-sur-Yvette (France). Dept. des Procedes d'Enrichissement-SEPC; CEA Marcoule, 30 (France). Service de Confinement des Dechets
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR9905905014378
Availability:
Available from INIS in electronic form
Submitting Site:
INIS
Size:
191 page(s)
Announcement Date:
Dec 18, 2000

Citation Formats

Delorme, Ludovic. Volatility mechanisms of borosilicate glasses and molten glasses of nuclear interest structural effects; Mecanismes de volatilite des verres et des fontes borosilicates d'interet nucleaire influence de la structure. France: N. p., 1998. Web.
Delorme, Ludovic. Volatility mechanisms of borosilicate glasses and molten glasses of nuclear interest structural effects; Mecanismes de volatilite des verres et des fontes borosilicates d'interet nucleaire influence de la structure. France.
Delorme, Ludovic. 1998. "Volatility mechanisms of borosilicate glasses and molten glasses of nuclear interest structural effects; Mecanismes de volatilite des verres et des fontes borosilicates d'interet nucleaire influence de la structure." France.
@misc{etde_20049650,
title = {Volatility mechanisms of borosilicate glasses and molten glasses of nuclear interest structural effects; Mecanismes de volatilite des verres et des fontes borosilicates d'interet nucleaire influence de la structure}
author = {Delorme, Ludovic}
abstractNote = {This work is devoted to the study of the mechanisms which control the volatility of the reference glass used for the confinement of radioactive waste. It was conducted on simplified compositions, in the SiO{sub 2}-B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-αNa{sub 2}O-(1-alpha)Li{sub 2}O-CaO system.The structural approach carried out by NMR, from room temperature up to 1500 °C, shows a strong increase in the mobility of alkalis above Tg. A rapid exchange between B{sup III} and B{sup IV} sites near 700 °C, and the change of coordination number B{sup IV} - B{sup III} near 1100 °C, also seem to take place. The analysis of the vapor phase, carried out by High Temperature Mass Spectrometry coupled to Knudsen cells, reveals the presence between 780 °C and 830 °C of NaBO{sub 2}(g), LiBO{sub 2}(g) and Na{sub 2}(BO{sub 2})2(g). The calculation of the partial pressure of each species shows that the total pressure of simplified glasses is dominated by the contribution of sodium. To study the volatility of glasses at higher temperature, equipment using the Transpiration method was used. The analysis of the deposits indicate the presence at 1060 °C of the species quoted previously. The vaporization rate and the vapor density were determined for each composition studied in a saturated state. Thus, we show that the volatility of the reference glass can be simulated by that of a simplified glass. For α=1, the kinetic of vaporization between 1060 °C and 1200 °C reveals an evaporation from the surface associated with a mechanism of diffusion in the molten glass. This is similar to the volatility of the reference glass at 1060 °C. To finally explain these mechanisms on a microscopic basis, we develop a model of molecular interactions. Between 780 °C and 830 °C, these mechanisms are controlled by a strong attraction between Na{sub 2}O and Li{sub 2}O, which maintains the total vapor pressure on a quasi-constant lever up to α=0.27. (author) [French] Ce travail a pour objectif l'etude des mecanismes qui controlent la volatilite du verre de reference utilise pour le confinement des dechets radioactifs. Il a ete realise sur des compositions simplifiees, dans le systeme SiO{sub 2}-B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-αNa{sub 2}O-(1-α)Li{sub 2}O-CaO. L'approche structurale menee par RMN, depuis la temperature ambiante jusqu'a 1500°C, met en evidence une forte augmentation de la mobilite des alcalins au dessus de Tg. Un echange rapide entre les sites de B{sup III} et B{sup IV} vers 700°C et le changement de coordinence B{sup IV} - B{sup III} vers 1100°C semblent egalement avoir lieu. L'analyse de la phase vapeur, effectuee par Spectrometrie de Masse a haute temperature couplee a des cellules de Knudsen, revele la presence entre 780°C et 830°C de NaBO{sub 2}(g), LiBO{sub 2}(g) et NaBO{sub 2}(g), LiBO{sub 2}(g) and Na{sub 2}(BO{sub 2})2(g). Le calcul de la pression partielle de chaque espece montre que la pression totale des verres simplifies est dominee par la contribution du sodium. Pour etudier la volatilite des verres a plus haute temperature, un appareillage utilisant la methode de Transpiration a ete realise. Les analyses des condensats indiquent la presence a 1060°C des especes citees precedemment. Pour chaque composition etudiee en regime de saturation, la vitesse de vaporisation et la densite de vapeur totale sont determinees. Nous montrons ainsi que la volatilite du verre de reference peut etre simulee par celle d'un verre simplifie. Pour α=l , la cinetique de vaporisation entre 1060°C et 1200°C met en evidence une evaporation en surface associee a un mecanisme de diffusion dans le verre fondu. Il en est de meme pour la volatilite du verre de reference a 1060°C. Pour determiner enfin l'origine microscopique de ces mecanismes, nous developpons un modele d'interactions moleculaires. Entre 780°C et 830°C, ces mecanismes sont controles par la forte attraction entre Na{sub 2}O et Li{sub 2}O. Cette derniere maintient la pression de vapeur totale a un niveau quasi-constant jusqu'a α=0.27. (auteur)}
place = {France}
year = {1998}
month = {Apr}
}