Report of drilling and radionuclide migration investigations at UE20n. number sign. 1, Pahute Mesa, Nevada Test Site, 1987
Exploratory hole UE20n{number sign}1 was drilled 305 m down hydraulic gradient of the Cheshire event (U20n) as part of the Radionuclide Migration Program at the Nevada Test Site. The hole was designed to investigate the possibility of groundwater transport of radionuclides from the U20n cavity region. Drilling reached a total depth of 1005.8 m. Composite static water levels in the borehole were measured at approximately 620 m below ground surface. The borehole penetrated about 386 m of saturated zone, which was comprised primarily of rhyolite lava flows of the Upper Rhyolite Lavas, Tuffs, and Rhyolites of Area 20. Evidence from UE20n{number sign}1 suggests the presence of a relatively more permeable zone in the 730 to 750-m depth interval. The neutron log suggests that greater quantities of water were present at depths between 729 and 747 m. Core collected over three depth intervals showed the highest fracture density in a reddish-grey rhyolite lava flow in the 733.8 to 738.1-m core interval. Groundwater flow away from U20n through this permeable zone is suggested by the UE20n{number sign}1 borehole temperature logs. Elevated {sup 3}H activities were observed with the highest activities found near 732 m. The {sup 3}H activities observed in the 732 to 802-m interval in UE20n{number sign}1 were of similar magnitude to those found in the cavity region in the U20n post-shot hole. The activities of {sup 125}Sb and {sup 85}Kr, which are known to be mobile in groundwater, were of similar magnitude to those found near the cavity region, while {sup 137}Cs, which is thought to be adsorbed during transport, was found in activities two to three orders of magnitude lower than near the cavity. These temperature and radioisotope data suggest that radionuclide migration via groundwater flow may be occurring laterally from the U20n rubble chimney through the permeable zone located at the 730 to 750-m depth. 25 refs., 18 figs., 15 tabs.
- Research Organization:
- Nevada Univ., Reno, NV (USA). Water Resources Center
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- AC08-85NV10384
- OSTI ID:
- 5708247
- Report Number(s):
- DOE/NV/10384-35; ON: DE91011273
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BOREHOLES
WELL LOGGING
GROUND WATER
RADIONUCLIDE MIGRATION
NEVADA TEST SITE
HYDROLOGY
ANTIMONY 125
CESIUM 137
COMPILED DATA
DRILL CORES
DRILLING
FRACTURES
KRYPTON 85
MONITORING
NEUTRON LOGGING
PROGRESS REPORT
RESEARCH PROGRAMS
RHYOLITES
SUBSURFACE ENVIRONMENTS
TEMPERATURE LOGGING
TRITIUM
TUFF
WATER TABLES
WATER WELLS
ALKALI METAL ISOTOPES
ANTIMONY ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CAVITIES
CESIUM ISOTOPES
DATA
DOCUMENT TYPES
ENVIRONMENTAL TRANSPORT
EVEN-ODD NUCLEI
FAILURES
HOURS LIVING RADIOISOTOPES
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
IGNEOUS ROCKS
INFORMATION
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
KRYPTON ISOTOPES
LIGHT NUCLEI
MASS TRANSFER
MICROSEC LIVING RADIOISOTOPES
NATIONAL ORGANIZATIONS
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
RADIOACTIVITY LOGGING
RADIOISOTOPES
ROCKS
US DOE
US ORGANIZATIONS
VOLCANIC ROCKS
WATER
WELLS
YEARS LIVING RADIOISOTOPES
540330* - Environment
Aquatic- Radioactive Materials Monitoring & Transport- (1990-)
540230 - Environment
Terrestrial- Radioactive Materials Monitoring & Transport- (1990-)