Effect of radon transport in groundwater upon gamma-ray borehole logs

Technical Report · Mon Sep 01 04:00:00 EDT 1980

DOI:https://doi.org/10.2172/5180056· OSTI ID:5180056

Nelson, P H; Rachiele, R; Smith, A

Granitic rock at an experimental waste storage site at Stripa, Sweden, is unusually high in natural radioelements (40 ppM uranium) with higher concentrations occurring locally in thin chloritic zones and fractures. Groundwater seeping through fractures into open boreholes is consequently highly anomalous in its radon content, with activity as high as one microcurie per liter. When total count gamma-ray logs are run in boreholes where groundwater inflow is appreciable, the result is quite unusual: the radon daughter activity in the water adds considerably to the contribution from the rock, and in fact often dominates the log response. The total gamma activity increases where radon-charged groundwater enters a borehole, and remains at a high level as the water flows along the hole in response to the hydraulic gradient. As a consequence, the gamma log serves as a flow profile, locating zones of water entry (or loss) by an increase (or decrease) in the total gamma activity. A simple model has been developed for flow through a thin crack emanating radon at a rate E showing that the radon concentration of water entering a hole is E/..lambda..h, where ..lambda.. is the radon decay rate and h the crack aperture, assuming that the flow rate and crack source area are such that an element of water resides within the source area for several radon half-lives or more. Concentration measurements can provide a measurement of the inflow rate. Data from the 127-mm holes in the time-scale drift behave in this fashion.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5180056
• Report Number(s): LBL-11180; SAC-30; ON: DE82012616
• Country of Publication: United States
• Language: English

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54 ENVIRONMENTAL SCIENCES
AIR
AIR QUALITY
BOREHOLES
CAVITIES
DETECTION
DRILL CORES
ELEMENTS
ENVIRONMENTAL QUALITY
ENVIRONMENTAL TRANSPORT
EUROPE
FAILURES
FLOW MODELS
FLUIDS
FRACTURES
GAMMA LOGGING
GASES
GRANITES
GROUND WATER
HYDROGEN COMPOUNDS
IGNEOUS ROCKS
MANAGEMENT
MASS TRANSFER
MATHEMATICAL MODELS
MONITORING
NATURAL RADIOACTIVITY
NONMETALS
OXYGEN COMPOUNDS
PLUTONIC ROCKS
RADIATION MONITORING
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVITY
RADIOACTIVITY LOGGING
RADIONUCLIDE MIGRATION
RADON
RARE GASES
ROCK CAVERNS
ROCKS
SCANDINAVIA
SWEDEN
UNDERGROUND DISPOSAL
WASTE DISPOSAL
WASTE MANAGEMENT
WATER
WELL LOGGING
WESTERN EUROPE