Technique for correcting for overburden effects in ground level radiometric surveys of uranium ore bodies

An experimental study of the effect of barren overburden on the gamma-ray spectrum of uranium ore has been made. This has shown that counts in either of the two energy windows 0.56 to 0.64 MeV or 0.66 to 1.01 MeV may be used to correct for the decrease in total count rate as a result of overburden. The correction is limited to an overburden thickness-density product of approximately 60 g/cm2, which is equivalent to a correction factor of 16. Theoretical spectra have been modeled for a geometry similar to that used in the experiment and agree in the changes in spectral shape with overburden thickness. The calculations have also been used to evaluate the effects of one thickness and to determine the useful limits of the correction factors. The method is mainly applicable to a mining environment where sufficiently high count rates exist