Radioactivity of building materials and the gamma radiation in dwellings in Belo Horizonte, Brazil

Building materials are known to contain naturally occurring radioactive materials (NORM). The radionuclides which contribute to the external exposure are 40 K and the gamma emitters members of the natural decay series 238U, 235U and 232Th. Samples of the statistically more important buildings materials utilized in the Metropolitan area of Belo Horizonte were collected and their uranium and thorium concentration were determined by INAA. The gamma emitters were spectrometrically determined by solid state detectors HPGe in a very low background laboratory. A model room was used for calculating the indoor mean exposure in dwellings. Due to the lack of regulation for radioactivity in buildings in Brazil, the measured activity concentration was compared with those of other countries. A discussion about the utilization of building material containing TENORM industrial residues is presented. (author)