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Title: Nuclear Waste Glass Durability: I, Predicting Environmental Response from Thermodynamic (Pourbaix) Diagrams

Conference · · Journal of the American Ceramic Society
 [1]
  1. Du Pont de Nemours (E.I.) and Co., Aiken, SC (United States). Savannah River Lab.

Pourbaix diagrams are shown to conceptually explain dissolution of glasses in terms of their thermodynamic stability and surface layer formation. To predict the long-term effects of ground-water contact on the durability of nuclear waste glass in a geologic repository, the nature of the glass dissolution process has been extensively examined. Hydration thermodynamics has been used to quantify the role of glass composition and the effect of solution pH. The glass compositions examined vary widely in composition and include natural, lunar, medieval, and nuclear waste glasses, as well as some glass-ceramics. The known effects of solution pH and oxidation potential (Eh) on glass dissolution are empirically described by thermodynamically calculated Pourbaix diagrams. Statistical analysis of over 300 glass durability tests demonstrates that the Pourbaix diagram can be quantified because of (1) the colinearity of the hydration free energy with solution pH defined by the Nernst equation and (2) the colinearity of the solution pH with the concentration of dissolved silicon and boron in the solution defined by the pH dependence of the ion activities. Construction of Pourbaix diagrams to describe glass dissolution serves to unify and categorize various existing experimental glass dissolution data.

Research Organization:
Du Pont de Nemours (E.I.) and Co., Aiken, SC (United States). Savannah River Lab.
Sponsoring Organization:
USDOE
DOE Contract Number:
AC09-89SR18035; AC09-76SR00001
OSTI ID:
6171408
Report Number(s):
DP-MS-87-2-Rev.1; CONF-870422-14-Rev.1; ON: DE91009320
Journal Information:
Journal of the American Ceramic Society, Vol. 75, Issue 9; Conference: 89. Annual Meeting of the American Ceramic Society, Pittsburgh, PA (United States), 26-30 Apr 1987; ISSN 0002-7820
Publisher:
American Ceramic Society
Country of Publication:
United States
Language:
English

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