Naturally occurring glasses: analogues for radioactive waste forms
Volcanic glasses are very often altered by weathering and leaching and recrystallize to their fine-grained equivalents (rhyolites, felsites). The oldest volcanic glasses are dated at 40 million years before the present, but the majority are much younger. Devitrification textures was produced experimentally; and hydration rates for volcanic glasses were determined as a function of composition, temperature, and climate. Presence of water and temperature are the most important rate controlling variables. Even material that may still be described as glassy often exhibits evidence of alteration and recrystallization. Of the volcanic glasses that are preserved in the geologic record, it would be rare to describe such a glass as pristine. Despite the common alteration and recrystallization effects observed in volcanic glasses, glasses formed as a result of impact, tektites and lunar glasses, may occur in substantially unaltered form. In the case of tektites, their resistance to alteration is a result of their high SiO/sub 2/ content and low alkali content. Lunar glasses have been preserved for hundreds of millions of years because they exist in an environment with a low oxygen fugacity and an extremely low water vapor partial presssure. Thus one might expect glasses of particular compositions or in specific types of environment to be stable for long periods of time. These conclusions are applied to radioactive waste disposal over several time periods (0-30h, 30h-20y, 20-200y).
- Research Organization:
- Battelle Pacific Northwest Labs., Richland, WA (United States)
- DOE Contract Number:
- EY-76-C-06-1830
- OSTI ID:
- 5993747
- Report Number(s):
- PNL-2776; TRN: 79-022077
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
GLASS
STABILITY
LUNAR MATERIALS
RADIOACTIVE WASTE DISPOSAL
PERFORMANCE
TEKTITES
VOLCANIC ROCKS
AGE ESTIMATION
CHEMICAL COMPOSITION
PHYSICAL PROPERTIES
RECRYSTALLIZATION
TIME DEPENDENCE
IGNEOUS ROCKS
MANAGEMENT
MINERALS
ROCKS
WASTE DISPOSAL
WASTE MANAGEMENT
052002* - Nuclear Fuels- Waste Disposal & Storage
580300 - Mineralogy
Petrology
& Rock Mechanics- (-1989)