Assessment and estimation of the effective dose due to external exposure from natural radioactivity of sands used in civil construction in the state of Rio de Janeiro,Brazil

The presence of naturally occurring radioactivity in sand and other building materials results in indoor and outdoor exposure to the public. Sand is one of the main components in civil construction alongside cement, crushed stone and bricks. Thus, this research was carried out in twenty sand samples with the objective of investigating the hazard indices of natural radiation, due to the presence of U-238, Ra-226, Th-232 and K-40 in sand samples collected in some locations in the state of Rio de Janeiro (Brazil), analyzing by gamma spectrometry and using an HPGe detector. The technique used for gamma analysis was gamma spectrometry, and the software used to analyze peaks and obtain counts was LabSOCS. In this context, the average activity concentration values of Ra-226 (66.7 +/- 1.2) and K-40 (647 +/- 31) Bq kg(-1) are higher than the world mean activity concentration of 50, 50 and 500 Bq kg(-1) for these three radionuclides. However, the value of Th-232 (40.6 +/- 0.7) Bq kg(-1) and Raeq (175 +/- 5) Bq kg(-1) are less than the world average of 50 Bq kg(-1) and 370 Bq kg(-1), respectively. The estimation of the average values for Annual Effective Dose (0.51 +/- 0.01) and Dutch Radiation Performance Index (0.52 +/- 0.01) was carried out, with values below the maximum recommended limit for the public. Only one sample had a higher value and the other samples are within the levels required for environmental control. However, the mean values found in this present study, when compared to those of other authors mentioned here, showed higher values. Therefore, most samples have safe values to be used by people in building their homes.