Application of a semi-empirical physical-mathematical model in determining the activity concentration of 226Ra in granites

Abstract

This study aimed to estimate the activity concentration of 226Ra in granite samples collected from various regions of Brazil, using a simplified semi-empirical physical-mathematical model. The importance of such an assessment lies in the fact that granite, widely used in construction, can be a source of radioactive contamination due to the presence of 226Ra, a precursor of 222Rn. 222Rn and its short-lived decay products are responsible for approximately 55 % of the internal radiation dose received by humans, and the emission of alpha particles by these radionuclides increases the risk of bone and lung cancer. To this end, indirect measurements of the activity concentration of 222Rn were performed using the AlphaGUARD detector, a rapid, convenient, and relatively inexpensive approach compared to traditional methods. The 226Ra activity concentrations obtained for the analyzed granite samples were 44.4 ± 7.2 Bq/kg, 23.4 ± 8.0 Bq/kg, 24.6 ± 7.8 Bq/kg, and 15.0 ± 5.1 Bq/kg. These results are below the reference levels established by national and international radiological protection agencies, indicating that the analyzed granites can be used without restrictions. The study was conducted in a laboratory, with samples provided by a marble company in Palmas, Paraná, Brazil. The conclusions reinforce the safety of using these materials, but also highlight the importance of continuous monitoring.