Review of the thermal stability and cation exchange properties of the zeolite minerals clinoptilolite, mordenite, and analcime; applications to radioactive waste isolation in silicic tuff
Silicic tuffs of the southern Great Basin and basalts of the Columbia River Plateau are under investigation as potential host rocks for high- and intermediate-level radioactive wastes. Nonwelded and partially welded tuffs may contain major amounts (> 50%) of the zeolite minerals clinoptilolite, mordenite, and analcime. Densely welded tuffs and some basalt flows may contain clinoptilolite as fracture filling that limits the permeability of these rocks. The cation exchange properties of these zeolite minerals allow them to pose a formidable natural barrier to the migration of cationic species of various radionuclides in aqueous solutions. However, these minerals are unstable at elevated temperatures and at low water-vapor pressures and may break down either by reversible dehydration or by irreversible mineralogical reactions. All the breakdown reactions occurring at increased temperature involve a net volume reduction and evolution of fluids. Thus, they may provide a pathway (shrinkage fractures) and a driving force (fluid pressure) for release of radionuclides to the biosphere. These reactions may be avoided by keeping zeolite-bearing horizons saturated with water and below about 85{sup 0}C. This may restrict allowable gross thermal loadings in waste repositories in volcanic rocks.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 59122
- Report Number(s):
- LA-8841-MS; ON: DE81026686
- Resource Relation:
- Other Information: PBD: Jun 1981
- Country of Publication:
- United States
- Language:
- English
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Physical and chemical properties of zeolite minerals occurring at the Yucca Mountain Site
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Related Subjects
58 GEOSCIENCES
RADIOACTIVE WASTE DISPOSAL
HIGH-LEVEL RADIOACTIVE WASTES
INTERMEDIATE-LEVEL RADIOACTIVE WASTES
TUFF
TEMPERATURE EFFECTS
CLINOPTILOLITE
MINERALOGY
MORDENITE
ANALCIME
UNDERGROUND DISPOSAL
COLUMBIA RIVER BASIN
DEHYDRATION
STABILITY
ION EXCHANGE
PERMEABILITY
Yucca Mountain Project