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The main sources of radon in the air of dwellings are soil, building materials, and groundwater. This study aimed to determine the exhalation rate of 222Rn from samples made of concrete and cement mortars, as well as to evaluate by means of gamma spectrometry the hazard indexes associated with other radionuclides present in the studied samples of building materials. The results obtained allowed the comparison of the exhalation rate of radon using theoretical calculations based on one-dimensional and three-dimensional models. Measurements of the activity concentration of radon in air was performed by AlphaGuard radon detector. Furthermore, obtained results were compared with the measurements performed inside the concrete test cells. These test cells were built with the aim of simulating a dwelling in small dimensions and to evaluate indoor radon activity associated with concrete. Consequently, the obtained results of radon exhalation rate, in becquerel per meter squared per hour, for the concrete was 2.55 ± 0.03 Bq·h−1·m−2 for the 1D model and 0.461 ±0.008 Bq·h−1·m−2 for the 3D model. The exhalation rate of radon, for the cement mortar was 1.58 ± 0.03 Bq·h−1·m−2 for the 1D model and 0.439 ± 0.011 Bq·h−1·m−2 for the 3D model. The indoor concentration of 222Rn from the test cell was 112 ± 9 Bq/m3. These values were below the limit of 300 Bq/m3 recommended by the International Commission on Radiological Protection (ICRP) and <148 Bq/m3, the limit recommended by the US Environmental Protection Agency (US EPA). Even so, these values should be the subject of concern since that activity is related only to the contribution of concrete walls.

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It was developed an improved theoretical model capable to estimate the radium concentration in building materials solely measuring the radon-222 concentration in a confined atmosphere.This non-destructive technique is not limited by the size of the samples, and it intrinsically includes back diffusion.The resulting equation provides the exact solution for the concentration of radon-222 as a function of time and distance in one dimension.The effective concentration of radium-226 is a fit parameter of this equation.In order to reduce its complexity, this equation was simplified considering two cases:low diffusion in the building material compared to the air, anda building material initially saturated with radon-222.These simplified versions of the exact one dimension solution were used to fit experimental data.Radon-222 concentration was continuously measured for twelve days with an AlphaGUARD detector, located at the Laboratory of Applied Nuclear Physics at Universidade Tecnologica Federal do Parana (UTFPR).This model was applied to two different materials: cement mortar and concrete, which results were respectively (15.7 +- 8.3) Bq/kg and (10.5 +- 2.4) Bq/kg for the radium-226 effective concentration.This estimation was confronted with the direct measurements of radium in the same materials (same sources) using gamma-ray spectrometry, fulfilled at Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), which results were respectively (13.81 +- 0.23) Bq/kg and (12.61 +- 0.22) Bq/kg.

This research objective was to assess the level of randon-222 concentration in well water of the metropolitan region of Curitiba, Paraná.Current work presents the results of indoor 222 Rn activity ground water samples from artesian wells from aquifers of the region. The studies of radon activity in water were performed using the radon detector for a construction project is implemented. In this case, it is observed that the radon concentrations decrease about 56% in the first water tank and 83% in the second water tank over the well. This fact shows that the actions for mitigation of radon are viable and do not require major modifications to the usual systems of construction.