Equilibrium modeling of the formation of zeolites in fractures at Yucca Mountain, Nevada
Yucca Mountain, in southern Nevada, is currently being investigated to determine its suitability to host the first US high-level nuclear waste repository. One of the reasons that Yucca Mountain was chosen for study is the presence of thick sequences of zeolite-rich horizons. In as much as fractures may serve as potential pathways for aqueous transport, the minerals that line fractures are of particular interest. Zeolites are common in fractures at Yucca Mountain and consist mainly of clinoptilolite/heulandite and mordenite although sporadic occurrences of chabazite, erionite, phillipsite, and stellrite have been identified using X-ray powder diffraction. To understand better the conditions under which the observed zeolite species were formed, thermodynamic data were estimated and calculations of log a((K{sup +}){sup 2}/Ca{sup ++}) versus log a((Na{sup +}){sup 2}/Ca{sup ++}) were conducted at various temperatures and silica activities. Using present-day Yucca Mountain water chemistries as a lower constraint on silica activity, clinoptilolite/heulandite and mordenite are still the zeolite species that would form under present conditions.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 139250
- Report Number(s):
- LA-UR--93-2761; CONF-9306100--4; ON: DE93018290
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
CALCIUM
CLINOPTILOLITE
GEOLOGIC FRACTURES
HEULANDITE
HIGH-LEVEL RADIOACTIVE WASTES
MINERALOGY
MORDENITE
PETROCHEMISTRY
RADIOACTIVE WASTE FACILITIES
RADIONUCLIDE MIGRATION
SILICA
THERMODYNAMICS
TUFF
UNDERGROUND DISPOSAL
WATER CHEMISTRY
YUCCA MOUNTAIN
Yucca Mountain Project
ZEOLITES