Quantitative radiometric measurement of radioactive ores in the natural occurrence

Abstract

The measurement of gamma radiation of radioactive ores in the natural deposit — directly in the face of a mine working or in a bore hole-permits determination of the radioactive element content in ores without collection of test samples and without chemical analyses. The accuracy of quantitative measurement by gamma rays depends to a considerable degree on correct interpretation of the spectral content of the gamma radiation measured. The gamma-ray spectra of radioactive ores is determined by the process of radiation dispersion and depends on the content of the ore. The intensity of gamma radiation registered by an ore seam depends on the cathode malarial of the counter (tungsten, copper, graphite) as a consequence of the difference in spectral sensitivity of various counters. The relationship of gamma — radiation intensity during measurement with a Geiger counter with various cathodes permits one to characterize the spectral composition of the ore's gamma radiation. In order to express the results in general units, microroentgens per hour, the radiometers are calibrated with an exact standard, but the calibration method does not exclude the radiometer reading dependence on the spectral sensitivity of the counters. In this article are determined the important conversion coefficients connecting gamma-radiation intensity with the content of radioactive elements in ore (see the table) during measurements on the ore seam surface or in borings. During measurements in borings the reverse dissemination of gamma rays having low energy is of great importance. By use of these coefficients calculations of the radioactive element content in ore from counter readings are carried out.