Hydrolysis of R7T7 Nuclear Waste Glass in Dilute Media: Mechanisms and Rate as a function of Ph

1990 ◽  
Vol 212 ◽  
Author(s):  
T. Advocat ◽  
J. L. Crovisier ◽  
E. Vernaz ◽  
G. Ehret ◽  
H. Charpentier
Keyword(s):  
Nuclear Waste ◽  
Aqueous Media ◽  
Glass Network ◽  
Surface Region ◽  
Waste Glass ◽  
Transition Elements ◽  
Acid Media ◽  
Glass Dissolution ◽  
Nuclear Waste Glass ◽  
Static Conditions

ABSTRACTR7T7 nuclear waste glass dissolution in highly dilute aqueous media under static conditions at 90°C occurs according to two different mechanisms depending on the solution acidity. In acid media (pH 4.8 and 5.5), preferential extraction of glass network modifiers results in the formation of an alkali metal-depleted surface region on which amorphous and crystallized (phosphate) compounds rich in transition elements precipitate. Steady-state dissolution conditions are not reached, as attested by variable normalized SI, B and Na mass losses. Glass dissolution is stoichiometric in basic media (pH 7 to 10): the strong bonds of the silicated network are broken at a rate that increases with the pH: the glass dissolution rate increases by a factor of 15 between pH 7 and 10. Under these conditions, alteration products at the glass/solution interface do not constitute a short-term kinetic barrier against the release of the major glass components.

Nature and Effect of the Alteration Layer During Nuclear Waste Glass Dissolution

2002 ◽  
Vol 713 ◽  
Author(s):  
A. Gauthier ◽  
P. Le Coustumer ◽  
J-H. Thomassin
Keyword(s):  
Nuclear Waste ◽  
Pure Water ◽  
Aqueous Media ◽  
Glass Dissolution ◽  
Icp Ms ◽  
Nuclear Waste Glass ◽  
Texture Structure ◽  
The Stability ◽  
Short Time

ABSTRACTThe goal of this study is to understand the role of the interface developed during R7T7 glass alteration. This glass has been leached in two different aqueous media (pure water, silica rich water and phosphorous rich water). The lixiviation tests have been optimized to assess the role of the alteration layer developed on the surface of the glass. The solution and the solid have been characterized by ICP-MS and TEM/X-EDS respectively. The results put in evidence that a complex alteration layer is formed. Its texture, structure and chemistry are discussed with respect to the evolution of the solution during the tests. The alteration layer is always present on the surface of the glass and is considered to control (at short time) diffusion of the different species through the layer. Further study must be undertaken to assess the evolution and the stability of the interface for longer time periods.

Secondary Phase Formation and the Microstructural Evolution of Surface Layers During Vapor Phase Alteration of the French Son68 Nuclear Waste Glass at 200 °C

1995 ◽  
Vol 412 ◽  
Author(s):  
W. L. Gong ◽  
R. C. Ewing ◽  
L. M. Wang ◽  
E. Vernaz ◽  
J. K. Bates ◽  
...  
Keyword(s):  
Surface Layer ◽  
Nuclear Waste ◽  
Vapor Phase ◽  
Rare Earths ◽  
Waste Glass ◽  
Transition Elements ◽  
Surface Layers ◽  
Crystalline Phases ◽  
Developed Surface ◽  
Nuclear Waste Glass

AbstractThe SON68 inactive “R7T7” composition is the French reference glass for the LWR nuclear waste glass. Vapor phase alteration was used to accelerate the reaction progress of glass corrosion and to develop the characteristic suite of secondary, alteration phases. Extensive solid-state characterization (AEM/SEM/HRTEM) was completed on six inactive R7T7 waste glasses which were altered in the presence of saturated water vapor (200 °C) for 91, 241, 908, 1000, 1013, and 1021 days. The AEM samples were examined in cross-section (lattice-fringe imaging, microdiffraction, and quantitative thin-film EDS analysis). The glass monoliths were invariably covered with a thin altered rind. The layer became thicker with time: 0.5μm for 22 days; 4 μm for 91 days; 6 μm for 241 days; 10 μm for 908 days; 26 μm for 1013 days; and <35μm for 1021 days. The composite alteration layer of the SON68 samples is at least four time less thick than that of the SRL 131 glass composition.Six distinctive zones, based on phase chemistry and microstructure, were distinguished within the well-developed surface layers. Numerous crystalline phases such as analcime, tobermorite, apatite, and weeksite were identified on the surfaces of the reacted glasses as precipitates. Two crystalline phases, Ag2TeO3 and (Ca,Sr)Mo3O9(OH)2, were found within the inner zones of surface layers, and they must have nucleated in situ, indicating that Ag, Te, Sr, and Mo can be retained within the surface layer. The majority of the surface layer volume is composed of two morphologically and chemically different structures: one consists of well-crystallized fibrous smectite aggregates occurring along with cavities, the A-domain; and the other consists of poorlycrystallized regions containing needle-like smectite (montmorillonite) crystallites, a silica-rich amorphous matrix, and possibly ZrO2 particles, the B-domain. The retention of rare-earths and Zr mostly occurred within B-domains and that of transition elements, such as Zn, Cr, Ni, and Mn, in A-domains. The recrystallization of poorly-crystallized B-domains into well-crystallized Adomains may influence the long-term behavior of rare-earths, Zr, and transition elements. The mechanism of surface layer formation during vapor phase alteration is discussed based on the cross-sectional AEM studies of surface layers of the SON68 waste glasses.

scholarly journals Progress toward bridging from atomistic to continuum modeling to predict nuclear waste glass dissolution.

2011 ◽  
Author(s):  
Peter Zapol ◽  
Ian Bourg ◽  
Louise Jacqueline Criscenti ◽  
Carl I. Steefel ◽  
Peter Andrew Schultz
Keyword(s):  
Nuclear Waste ◽  
Waste Glass ◽  
Continuum Modeling ◽  
Glass Dissolution ◽  
Nuclear Waste Glass

A mechanistic model for understanding nuclear waste glass dissolution

1992 ◽  
Vol 190 ◽  
pp. 191-197 ◽  
Author(s):  
F. Delage ◽  
D. Ghaleb ◽  
J.L. Dussossoy ◽  
O. Chevallier ◽  
E. Vernaz
Keyword(s):  
Nuclear Waste ◽  
Mechanistic Model ◽  
Waste Glass ◽  
Glass Dissolution ◽  
Nuclear Waste Glass

Infrared Spectroscopy Structural Analysis of Corroded Nuclear Waste Glass K-26

2008 ◽  
Author(s):  
Sergey Stefanovsky ◽  
Alexander Barinov ◽  
Galina Varlakova ◽  
Irene Startseva ◽  
Michael I. Ojovan
Keyword(s):  
Infrared Spectroscopy ◽  
Structural Analysis ◽  
Nuclear Waste ◽  
Waste Glass ◽  
Nuclear Waste Glass

scholarly journals History of Nuclear Waste Glass in France

2014 ◽  
Vol 7 ◽  
pp. 3-9 ◽  
Author(s):  
Étienne Vernaz ◽  
Jérôme Bruezière
Keyword(s):  
Nuclear Waste ◽  
Waste Glass ◽  
Nuclear Waste Glass ◽  
History Of

Hydrotalcite Formed by Alteration of R7T7 Nuclear Waste Glass and Basaltic Glass in Salt Brine at 190°C

1993 ◽  
Vol 333 ◽  
Author(s):  
A. Abdelouas ◽  
J. L. Crovisier ◽  
W. Lutze ◽  
R. Müller ◽  
W. Bernotat
Keyword(s):  
Nuclear Waste ◽  
Waste Glass ◽  
Aluminium Content ◽  
Basaltic Glass ◽  
Alteration Product ◽  
Nuclear Waste Glass ◽  
Salt Brine ◽  
High Aluminium ◽  
Early Alteration

ABSTRACTThe R7T7 and synthetic basaltic glasses were submitted to corrosion in a saline MgCl2dominated solution at 190°C. For both glasses, the early alteration product is a hydrotalcite-like compound in which HPO42-, SO4-2and Cl-substitutes to CO32. The measured d003spacing is 7.68 Å for the hydrotalcite formed from R7T7 glass and 7.62 Å for the hydrotalcite formed from basaltic glass which reflect the high aluminium content. Chemical microanalyses show that the hydrotalcite is subsequently covered by a silica-rich gel which evolves into saponite after few months.

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