Low energy gamma-ray spectrometry - A technique for estimation of high grade uranium in geological samples

Low Energy Gamma-Ray Spectrometry (LEGS) has been proved to be a rapid technique for analyzing high-grade uranium in geological samples. From the low energy portion between (40-400 keV) of the gamma-ray spectrum of uranium and thorium series, the contents of uranium, its daughter radium (eq), and thorium are determined. This gives significant information about the geochemical anomalies. A standard gamma ray spectrometer with a 1{3/4}' ' 2' well type NaI (Tl) gamma detector constitutes the instrumentation requirements of this technique. Sample weighing about a few grams in a glass vial is used for analysis. A detailed study on the contribution of uranium daughter's energies in gamma spectrum of uranium has made the system more efficient for analyzing high grade (20%) uraniferous samples. Minimum personal exposure and an excellent correlation of uranium values with the chemical results have made this technique a versatile one in high-grade uranium exploration programme. This paper deals with problems faced by the conventional methods that is Beta-Gamma and High Energy Gamma-Ray Spectrometry used for determining the contents of uranium and thorium in high-grade uraniferous geological samples and the advantage of this technique over them.