Radioactivity in beach and zircon sands processed in northeastern Brazil

Full text: The use of ores and other raw materials containing small but measurable amounts of natural radionuclides by the processing industry may enhance the concentration of those radionuclides and consequently cause radiological problems in workplaces and in the nearby environment. This is the case of plants that use beach sands in the production of zircon sands for use in the ceramic industry. This paper reports the results of a study carried out in a mineral sand processing plant located in the coastal region of Northeastern Brazil. The study aimed to determine the natural radionuclides content of the mineral products extracted from the sand, with special emphasis on zircon. Measurements were performed through gamma spectrometry, by using a high purity germanium detector (HPGe) coupled to a multichannel analyzer. Activity concentrations of 226Ra and 228Ra were determined in both raw and zircon sands by measuring some of the radon progeny activity concentrations (214Pb and 214Bi for 226Ra and 228Ac, 212Pb, and 208Tl for 228Ra). The results of the measurements carried out in raw sand samples showed average activity concentrations of 24.2 ± 3.4 and 35.4 ± 5.4 Bq kg-1 for 226Ra and 228Ra, respectively. For the zircon sand samples, on the other hand, activity concentrations ranged from 16.7 ± 1.6 to 45.4 ± 8.3 kBq kg-1 for 226Ra. The results for 228Ra, were consistently lower than those obtained for 226Ra, ranging from 3.0 ± 0.4 to 19.9 ± 1.2 kBq kg-1. Activity concentrations measured in this work are of the same order of magnitude of the ones found in other parts of the world. The results are analyzed on the basis of the Brazilian regulations concerning the safety requirements and radiation protection in industrial facilities that process raw material containing radionuclides of the uranium and thorium natural series