Quali-quantitative radiometric characterization of thorianite minerals seized in Brazil

Radioactive minerals in the process of being smuggled were seized in the North Region of Brazil. As it is a practically unknown material, the quali-quantitative characterization of a subsample of the mineral was conducted, using High-Resolution Gamma-Ray Spectrometry (HRGRS). Self-attenuation correction by means of quali-quantitative analysis through Energy Dispersion X-Ray Fluorescence (EDXRF) was deemed necessary due to the incongruence among the results of the gamma energies. The respective average values of activity concentrations (ACs) were estimated at 3.08 MBq kg −1 (± 0.10 MBq kg −1 ) and 1.37 MBq kg −1 (± 0.12 MBq kg −1 ) for 232 Th and 238 U. With the concentrations converted from 86 and 13% for ThO 2 and U 3 O 8 , respectively, it was confirmed that the mineral was predominantly thorianite (U/Th ratio below 20%) and of a high risk of the population’s exposure to ionizing radiation.