A Kinetic Model of Nuclear Waste Glass Dissolution in Flowing Water Environments

1984 ◽  
Vol 44 ◽  
Author(s):  
Aaron Barkatt ◽  
Barbara C. Gibson ◽  
Marek Brandys
Keyword(s):  
Kinetic Model ◽  
Nuclear Waste ◽  
Flow Rate ◽  
Flowing Water ◽  
Flow Rates ◽  
Glass Dissolution ◽  
Nuclear Waste Glass ◽  
Simple Kinetic Model ◽  
Leachate Composition ◽  
Flow Experiments

AbstractA simple kinetic model for the description of the interaction of nuclear waste borosilicate glass with water has been developed. In the case of SRL TDS-131 glass leached in water at 70°C over a broad range of flow rates this model was found useful both in describing the evolution of leachate composition as a function of exposure time at a particular flow rate and in describing the dependence of the steady-state concentrations of the leached elements in solution on flow rate in a series of flow experiments.

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.

Effects of Flow Parameters on the Leaching of Nuclear Waste Glass

1984 ◽  
Vol 44 ◽  
Author(s):  
R. B. Adiga ◽  
E. P. Akomer ◽  
D. E. Clark
Keyword(s):  
Nuclear Waste ◽  
Flow Rate ◽  
Volume Ratio ◽  
Water Volume ◽  
Leaching Rate ◽  
Leaching Behavior ◽  
Waste Package ◽  
Flow Parameters ◽  
Nuclear Waste Glass ◽  
Independent Effects

Environmental conditions in a repository are expected to be significantly different from those encountered by a glass tested under MCC-1 specifications. In addition to variations in flow rate and glass surface area to water volume ratio (SA/V), the water chemistry and presence of waste package components in the repository will most certainly affect the leaching behavior of the glass. The independent effects of each of these variables have been studied by numerous investigators. For example, it is well known that the leaching rate increases as the flow rate increases (1). Also, the rate of approach to saturation is increased as SA/V is increased under MCC-1 type testing (2). The use of silicate water generally decreases the rate of leaching while waste package components such as iron enhances the leaching rate of glass under MCC-1 type testing (3–4).

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.

Characterization of Lanthanoid Phases Formed Upon Glass Dissolution in Salt Solutions

1991 ◽  
Vol 257 ◽  
Author(s):  
Anette Rother ◽  
Werner Lutze ◽  
Peter Schubert-Bischoff
Keyword(s):  
Nuclear Waste ◽  
Solid Solutions ◽  
Type Material ◽  
Salt Solutions ◽  
Detailed Characterization ◽  
Glass Dissolution ◽  
Nuclear Waste Glass ◽  
Solid Phases ◽  
Additional Barrier

ABSTRACTThis communication gives a detailed characterization of some molybdate solid solutions and cerianite-type material which formed on the French borosilicate nuclear waste glass R7T7 upon corrosion in various saturated salt solutions at 110°C, 150 °C and 190 °C. The glass contained lanthanoid elements, such as neodymium, lanthanum, praseodymium, cerium and yttrium, but did not contain actinoid elements, except uranium and thorium. Various solid solutions containing lanthanoids (Ln) were found on the glass surface after corrosion, including powellite solid solutions and cerianite-type material. The secondary solid phases are characterized based on quantitative microchemical and structural analyses. These phases are expected to incorporate actinoids such as americium and curium in acid magnesiumcontaining salt solutions. The phases then constitute an additional barrier against migration of these radionuclides, which would otherwise be in the aqueous phase.

scholarly journals Forty years of durability assessment of nuclear waste glass by standard methods

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Clare L. Thorpe ◽  
James J. Neeway ◽  
Carolyn I. Pearce ◽  
Russell J. Hand ◽  
Adam J. Fisher ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Nuclear Waste ◽  
Glass Composition ◽  
Radioactive Waste Disposal ◽  
Experimental Conditions ◽  
Standard Methods ◽  
Glass Dissolution ◽  
Nuclear Waste Glass ◽  
Safety Case ◽  
Durability Assessment

AbstractStandard methods to assess the durability of vitrified radioactive waste were first developed in the 1980’s and, over the last 40 years, have evolved to yield a range of responses depending on experimental conditions and glass composition. Mechanistic understanding of glass dissolution has progressed in parallel, enhancing our interpretation of the data acquired. With the implementation of subsurface disposal for vitrified radioactive waste drawing closer, it is timely to review the available standard methodologies and reflect upon their relative advantages, limitations, and how the data obtained can be interpreted to support the post-closure safety case for radioactive waste disposal.

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

Control of R7T7 Nuclear Glass Alteration Kinetics Under Saturation Conditions

1995 ◽  
Vol 412 ◽  
Author(s):  
S. Gin
Keyword(s):  
Critical Role ◽  
Solution Flow Rate ◽  
Additional Experiment ◽  
Solution Flow ◽  
Flow Rates ◽  
Dissolved Silica ◽  
Glass Dissolution ◽  
Geological Repository ◽  
Nuclear Waste Glass

AbstractThe hypothesis of French nuclear waste glass disposal in a geological repository implies a comprehensive assessment of all the glass elements liable to participate in controlling the material alteration kinetics. The hypothetical existence of kinetically limiting elements other than silica could account for the observed R7T7 glass behavior in the presence of certain clays, and notably the continued high alteration rates observed even after silica saturation occurs. Flowing experiments with solutions near silica saturation but highly subsaturated with respect to aluminum hydroxide were defined to investigate the possible limiting role of aluminum. Experiments were conducted at different flow rates with the same constant steady-state H4 SiO4 activity for all the tests. The glass dissolution rate was observed to depend on the solution flow rate, indicating that under these conditions the kinetics are not controlled by dissolved silica alone. An additional experiment, in which only the Al(OH)4− activity in solution was allowed to vary, demonstrated the critical role of this element. Several interpretations are discussed.

Dissolution of R7T7 Glass in Static and Flowing Conditions: Influence of Si Diffusion Mechanism in the Leached Layer

1992 ◽  
Vol 294 ◽  
Author(s):  
F. Delage ◽  
F. Larche ◽  
E. Vernaz
Keyword(s):  
Nuclear Waste ◽  
Mechanistic Model ◽  
Diffusion Mechanism ◽  
Interstitial Solution ◽  
First Order ◽  
Glass Dissolution ◽  
Nuclear Waste Glass ◽  
Empirical Law ◽  
Mass Transport Equation ◽  
Silicon Diffusion

ABSTRACTLeach tests with R7T7 nuclear waste glass in distilled water were conducted at 50 and 90°C under static and slow flowing conditions, with an SA/V ratio of 50 m−1. A computer model for glass dissolution (LIXIVER) Was used to interpret the experimental data. This mechanistic model is based on a combination of the first-order law governing surface reactions, the silicon mass transport equation for the interstitial solution in the alteration film, and an empirical law for partial silicon retention in the alteration layer. The LIXIVER model satisfactorily accounts for most of the experimental results. The importance of the silicon diffusion mechanism in the diffusion layer is stressed. Values are indicated for the apparent silicon diffusion coefficient, Dsi, which ranged from 10−16 to 10−14 m2·s−1 at 50°C, and from 10−15 to 10−13 m2·s−1 at 90°C.

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