The effect of glass composition on the experimental hydration of obsidian between 110 and 230{degree}C

Mazer, J.J.; Bates, J. K.; Stevenson, Christopher M.; Bradley, James P.

doi:10.2172/10144526

Cited by 1 publication

(3 citation statements)

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“…The rate of formation of the birefringent hydration layers was constant as a function of the square root of time, Figure 1, in excellent agreement with previous reports of obsidian hydration [1,3,9,10]. The isothermal rate constants for the different obsidians varied by more than a factor of two.…”

Section: Resultssupporting

confidence: 89%

“…The temperature dependence of the reaction is characterized by an activation energy that ranged between 75 to 100 kJ/mol, Figure 3, and also shows a strong correlation with the initial total water content of glass. These results are described in greater detail elsewhere [3], but their significance is that we are able to quantitatively describe molecular water diffusion in silicate glasses as a function of glass composition and temperature over a range of conditions relevant to the proposed Yucca Mountain repository. …”

Section: Resultsmentioning

confidence: 80%

“…diffusion* [1][2][3]. Because this system is dominated by molecular water diffusion, it • allows us to isolate and quantify molecular water diffusion without interference from alkali exchange or etching, an option not possible with basalt glasses.…”

Section: Introductionmentioning

confidence: 99%

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Obsidians and Tektites: Natural Analogues for Water Diffusion in Nuclear Waste Glasses

Mazer

Bates

Stevenson³

et al. 1991

MRS Proc.

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Molecular water diffusion in natural obsidians and tektite was investigated in vapor hydration tests performed between 75 and 230°C for up to 400 days. Reaction progress was monitored using measurements of the birefringent hydration layer, an alteration feature associated with strain caused by molecular water diffusion in obsidians. The hydration rate constants and temperature dependence of the reaction are strongly correlated with the logarithm of the initial total water content of the glass. These values have been quantified for conditions relevant to the potential Yucca Mountain repository. The low initial total water concentrations of Savannah River Lab nuclear waste glasses produced at the bench-top scale help to minimze the effects of molecular water diffusion in waste glasses. The results of this study indicate that molecular water diffusion does not dominate waste glass reactions under conditions considered in this study. However, it is unknown whether molecular water diffusion will be important under other reaction conditions, especially longer time periods.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 80%