Gamma-Ray Logging in Uranium Prospecting

Gamma-ray systems that have a wide range response are required for uranium exploration. Low-grade ore bodies with marginal economic feasibility are particularly dependent on reliable, calibrated gamma-ray logs. Wide range gamma-ray counting systems for this purpose are described, with particular emphasis on the downhole wide range gamma-gross count probe. Gamma-detector types, calibration of the system, and interpretation methods are reviewed. The 'hardware' characteristics are detailed to provide an understanding of equipment capabilities and limitations. It is necessary to discriminate between the valuable uranium ore and other radioactive materials, at present of little value. Therefore gamma-spectral logs are of considerable interest but available equipment limits the use of such techniques. Equipment limitations and possible improvements, such as use of coaxial logging cables, are covered, with actual field conditions being considered. (author)