scholarly journals Prediction of Glass Durability as a Function of Environmental Conditions

1988 ◽  
Vol 125 ◽  
Author(s):  
C. M. Jantzen
Keyword(s):  
Nuclear Waste ◽  
Environmental Conditions ◽  
Glass Composition ◽  
Oxidation Potential ◽  
Natural Environments ◽  
Matrix Elements ◽  
Hydration Free Energy ◽  
Solution Ph ◽  
Pourbaix Diagrams ◽  
Glass Dissolution

ABSTRACTA thermodynamic model of glass durability has been applied to natural, ancient, and nuclear waste glasses. The durabilities of over 150 different natural and man-made glasses, including actual ancient Roman and Islamic glasses (Jalame ca. 350 A. D., Nishapur 10-11th century A. D., and Gorgon 9-11th century A.D.), have been compared. Glass durability has been shown to be a function of the thermodynamic hydration free energy, δGhvd, which can be calculated from glass composition and solution pH. Using this approach the durability of the most durable nuclear waste glasses examined was ˜106 years by comparison with the durability of the natural basalts of ˜106 years. The least durable waste glass formulations were comparable in durability to the most durable simulated medieval window glasses of ˜103 years. In this manner, the durability of nuclear waste glasses has been interpolated to be ˜106 years and no less than 103 years.Hydration thermodynamics have been shown to be applicable to the dissolution of glass in various natural environments. Groundwater-glass interactions relative to geologic disposal of nuclear waste, hydration rind dating of obsidians, and/or other archeological studies can be modeled, e.g. the relative durabilities of six simulated medieval window glasses have been correctly predicted for both laboratory (one month) and burial (5 year) experiments.The effects of solution pH on glass dissolution has been determined experimentally for the 150 different glasses and can be predicted theoretically by hydration thermodynamics. The effects of solution redox (oxidation potential expressed as Eh) on dissolution of glass matrix elements such as Si and B have been shown to be minimal. The combined effects of solution pH and Eh have been described and unified by construction of thermodynamically calculated Pourbaix (pH-Eh) diagrams for glass dissolution. The Pourbaix diagrams have been quantified to describe glass dissolution as a function of environmental conditions by use of the data derived from hydration thermodynamics.

scholarly journals Pourbaix Diagram for The Prediction of Waste Glass Durability in Geologic Environments

1987 ◽  
Vol 112 ◽  
Author(s):  
Carol M. Jantzen
Keyword(s):  
Nuclear Waste ◽  
Oxidation Potential ◽  
Waste Glass ◽  
Natural Environments ◽  
Long Term Effects ◽  
Pourbaix Diagrams ◽  
Nuclear Waste Glass ◽  
Corrosion Mechanisms ◽  
Different Time Scales

AbstractDissolution of nuclear waste glass occurs by corrosion mechanisms similar to those of metallurgical and mineralogic systems albeit on different time scales. The effects of imposed pH and oxidation potential (Eh) conditions existing in natural environments on metals and minerals have been quantatively and phenomenologically described in compendiums of Pourbaix (pH-potential) diagrams. Construction of Pourbaix diagrams to quantify the response of nuclear waste glasses to repository specific pH and Eh conditions is demonstrated. The expected long-term effects of groundwater contact on the durability of nuclear waste glasses can then be unified.

The effect of phosphate melt cooling rate on phase composition and leach resistance of final waste form

MRS Advances ◽  
2017 ◽  
Vol 3 (20) ◽  
pp. 1085-1091 ◽  
Author(s):  
Konstantin V. Martynov ◽  
Elena V. Zakharova ◽  
Sergey V. Stefanovsky ◽  
Boris F. Myasoedov
Keyword(s):  
Nuclear Waste ◽  
Glass Composition ◽  
Crystalline Material ◽  
Slow Cooling ◽  
Leach Rate ◽  
Glass Dissolution ◽  
Phosphate Phase ◽  
Partial Crystallization ◽  
Melt Cooling ◽  
Melt Solidification

ABSTRACTSlow cooling of phosphate melt at liquid nuclear waste solidification yields glass-crystalline material. Partial crystallization during melt solidification results in elemental partitioning among crystalline phase and glass: Al, Cr, Fe are concentrated in the crystalline phosphate phase while Ca, Ni, La, U enter predominantly in the residual glass. Glass dissolution rate and leach rate of La and U as rare earth and actinide surrogates depends strongly on the glass composition, for example reduction of Al2O3 content in the glass to ∼10-12 wt.% increases leachability by three orders of magnitude as compared to the glass with specified composition (∼18-22 wt.% Al2O3).

Non-Linearity in Glass Composition Dependence of Dissolution Rates: Effect of Solution pH

1993 ◽  
Vol 333 ◽  
Author(s):  
Shi-Ben Xing ◽  
Isabelle S. Muller ◽  
Ian L. Pegg
Keyword(s):  
Nuclear Waste ◽  
Glass Composition ◽  
Ph Dependence ◽  
Solution Ph ◽  
Ph Values ◽  
Waste Vitrification ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Soluble Components ◽  
Glass Compositions

ABSTRACTIn our previous studies on the optimization of glass compositions for high-level nuclear waste vitrification it was found that, over certain composition ranges, PCT leachate concentrations increased dramatically with very small changes in glass composition. The large differences that are observed between the leachate pH values for the “durable” and the “less-durable” glasses is one possible cause for this strongly non-linear glass composition effect; conversely, the pH difference may be merely another symptom. In this study, four simulated nuclear waste glasses (two of the less-durable and two of the durable types), were leached in both zwitterionic and inorganic buffer solutions, at fixed pH-values in the ranges of 7 to 12. The very different leaching behaviors of the two types of glasses persisted and, furthermore, different pH-dependence was found despite their very similar glass composition. This study suggests that the leachate pH difference observed between the less-durable and the durable glasses under uncontrolled pH conditions is not the major cause of the large difference of leaching behavior between those glasses. The normalized release ratios of soluble components (B, Li, Na) to Si show significant differences for the two types of glasses.

Effect of Surface Layers on the Dissolution of Nuclear Waste Glasses

1993 ◽  
Vol 333 ◽  
Author(s):  
Shi-Ben Xing ◽  
Andrew C. Buechele ◽  
Ian L. Pegg
Keyword(s):  
Surface Layer ◽  
Nuclear Waste ◽  
Glass Composition ◽  
Reaction Rates ◽  
Surface Layers ◽  
Linear Effect ◽  
Glass Dissolution ◽  
Important Challenge ◽  
Saturation Effects ◽  
Glass Powders

ABSTRACTExplanation of the striking non-linear effect of glass composition on the aqueous dissolution represents an important challenge to existing dissolution mechanisms. Surface layers that are formed during glass dissolution may play an important role in this effect. One chemically reactive and one less-reactive nuclear waste glass (leachate concentrations differ by about a factor of 10) were reacted in deionized water. Two types of glass powders were used: Type A powders were pristine glass powders; Type B powders were the glass powders which had been reacted for 120 days to develop the surface layers. Both the solution concentrations and the surface layers were investigated. The experimental observations indicate that: (i) There is a range of glass compositions over which small differences in composition lead to large changes in both reaction rates and surface layer thickness; and (ii) The reaction rate is strongly affected by the formation of the surface layer (the layer appears to be protective) and cannot be explained in terms of saturation effects alone. The findings are contrary to the conclusion of a previous study and serve to highlight the inadequacy of existing dissolution models predicated on an overly simplistic mechanism, especially with regard to glass composition effects.

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.

THE KILLER OF NATURE – ENVIRONMENTAL DEGRADATION

2015 ◽  
Vol 3 (3) ◽  
pp. 293-295
Author(s):  
Ekta Sharma
Keyword(s):  
Environmental Degradation ◽  
Environmental Conditions ◽  
The Other ◽  
Natural Environments ◽  
Human Being ◽  
Human Beings ◽  
The Public ◽  
Summary Paper ◽  
Living Being

The Presented summary paper target is to draw the attention of the public to the benefits of Environment and how we are connected to the Environment. To show that if there’s any change in the Environmental conditions, then how the conditions change in human beings lives. Living Being, whether a Human Being or Animals or plants,  are all directly or indirectly Dependent on the Environment for their Survival. When asked truly it can be said that none of the living being can survive without the presence of Environment. It is difficult to find absolutely natural environments, and it is common that the naturalness varies in a continuum, from ideally 100% natural in one extreme to 0% natural in the other. More precisely, we can consider the different aspects or components of an environment, and see that their degree of naturalness is not uniform.

scholarly journals Does Fully Radioactive Glass Behave Differently than Simulated Waste Glass?

1992 ◽  
Vol 294 ◽  
Author(s):  
X. Feng ◽  
J. K. Bates ◽  
C. R. Bradley ◽  
E. C. Buck
Keyword(s):  
Radiation Field ◽  
Nuclear Waste ◽  
Potassium Feldspar ◽  
Waste Glass ◽  
Solution Ph ◽  
Static Tests ◽  
Leach Rate ◽  
Nuclear Waste Glass ◽  
Surface Alteration ◽  
Leach Behavior

ABSTRACTStatic tests at SA/V (ratio of surface area of glass to solution volume) 20,000 m−1 on SRL 200 glass compositions show that, at long test periods, the simulated nuclear waste glass (nonradioactive) leaches faster than the corresponding radioactive glass by a factor of about 40, although comparative tests, done through 560 days, at lower SA/V, 2000 m−1, indicate little difference in the leach behavior of the two types of glasses. The similarity in leach behavior between radioactive and simulated glasses at SAN of 2000 m−1 or lower is also observed for SRL 165/42 and 131/11 compositions. The accelerated glass reaction with the simulated glass 200S is associated with the formation of crystalline phases such as clinoptilolite (or potassium feldspar), and a pH excursion. The radiation field generated by the fully radioactive glass reduces the solution pH. This lower pH, in turn, may retard the onset of increased reaction rate. The radiation field generated by the radioactive glasses does not directly affect the stability of the glass surface alteration layer under those conditions where the radioactive and simulated glasses react at the same rate. These results suggest that the fully radioactive nuclear waste glass 200R may maintain a much lower leach rate than the simulated 200S, if the lower pH in the 200R leachate can be sustained. Meaningful comparison tests between radioactive and simulated nuclear waste glasses should include long-term and high SA/V tests.

Picloram Absorption by Broom Snakeweed (Gutierrezia sarothrae) Leaf Tissue

Weed Science ◽  
1992 ◽  
Vol 40 (3) ◽  
pp. 390-394 ◽  
Author(s):  
Tracy M. Sterling ◽  
Norman K. Lownds
Keyword(s):  
Relative Humidity ◽  
Environmental Conditions ◽  
Leaf Tissue ◽  
Axillary Bud ◽  
Solution Ph ◽  
Simple Diffusion ◽  
Foliar Absorption ◽  
Ph Dependent ◽  
Gutierrezia Sarothrae ◽  
Diffusion Absorption

Foliar absorption of picloram by broom snakeweed, a rangeland shrub, was investigated. Picloram uptake into leaf, axillary bud, and stem tissues was similar. In addition, picloram uptake by leaf tissue from greenhouse- and field-grown broom snakeweed did not differ. Picloram accumulated rapidly and absorption saturated between 15 min and 1 h of application; no further absorption occurred through 72 h with maximum uptake ca. 15% of applied picloram. Picloram content increased linearly with increasing external picloram concentration, implying that movement of the herbicide across the cuticle is via diffusion. Absorption was dependent on relative humidity and temperature with the greatest uptake at 94% relative humidity and 35 C, respectively. Absorption was pH dependent; picloram absorption was greatest at pH 4 and least at pH 8. In addition, picloram absorption was less at pH 3 compared to pH 4. These results provide evidence that picloram is absorbed across the cuticle via simple diffusion and absorption is dependent on environmental conditions and solution pH at and following application.

Studies of Ancient Glass and Their Application to Nuclear-Waste Management

MRS Bulletin ◽  
2003 ◽  
Vol 28 (7) ◽  
pp. 500-504 ◽  
Author(s):  
Hannelore Römich
Keyword(s):  
Waste Management ◽  
Nuclear Waste ◽  
Laboratory Experiments ◽  
Glass Composition ◽  
Nuclear Waste Management ◽  
High Potassium ◽  
Ancient Glass ◽  
Long Term Behavior ◽  
High Potassium Content

AbstractDuring several hundred years of burial in the soil, glass objects, especially those with the high potassium content of medieval compositions, develop heavily corroded surfaces, showing phenomena such as local pitting, laminated layers, and browning effects. The long-term behavior of glass in the soil or in contact with groundwater is not only of interest to glass scientists with a background in archaeology, but also for those with a special interest in nuclear-waste management. Several attempts have been made to propose the decomposition of ancient glasses as an indicator for the performance of buried nuclear-waste glasses. In spite of differences in glass composition and exposure conditions, the development of alteration or corrosion layers with time is a common concern, as shown in this article. Laboratory experiments, representing a simplified model for real conditions, offer the possibility for systematic investigations.

Structural Thermodynamic Model for the Durability and Viscosity of Nuclear Waste Glasses

1987 ◽  
Vol 112 ◽  
Author(s):  
Xiangdong Feng ◽  
Aaron Barkatt
Keyword(s):  
Nuclear Waste ◽  
Composition Dependence ◽  
Glass Composition ◽  
Chemical Properties ◽  
Test Results ◽  
Structural Rules ◽  
Predominant Factor ◽  
Alkali Oxides ◽  
Bond Strengths ◽  
And Chemical Properties

AbstractA model based upon structural thermodynamic considerations has been proposed for both chemical durability and viscosity of nuclear waste glasses. This model assumes the bond strength between atoms in the glass to be the predominant factor in controlling the composition dependence of physical properties such as viscosity and chemical properties like durability. These characteristic bond strengths in the glass are obtained from known heats of formation of the constituent oxides with a few simple structural rules deduced by distinguishing the structural roles of the various oxides, i.e., separating those components that are clearly “network-formers” (e.g. SiO2, Al2O3, ZrO2) from those that are clearly “network-breakers” (e.g. alkali oxides). This model has been successfully applied to the correlation of glass composition with modified MCC-3 leach test results on nuclear waste glasses measured at various laboratories on one hand and with the viscosities of numerous glasses over a temperature range of 850°C to 1600°C with remarkable accuracy on the other hand.

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