Radioactivity Analysis Using Commercially Available Chemical Reagents as Calibration Sources

A calibration method of gamma-ray spectrometry for radionuclides in environmental samples has been developed using three natural radionuclides included in commercially available chemical reagents. A detection efficiency curve was obtained by measurements of 40K, 138La and 176Lu identified in gamma-ray spectra of chemical reagents KCl, LaF3 and Lu2O3, respectively. The detection efficiencies were calculated for gamma rays in the energy range from 202 to 1461 keV using standard sources. Validations were carried out with determinations of the activity concentrations in geochemical reference rock samples and radioactive standard materials. The experimental results for standard materials were in good agreement with the certified value. Thus method enables one to easily prepare a detection efficiency curve, and to estimate the activities of several radionuclides in environmental samples outside of a radiation controlled area.