Environmental gamma radiation and natural radioactivity in soils in Centro Experimental Aramar (CTMSP-BRAZIL) and region

The experimental results are described obtained with CaF2:Dy thermoluminescence dosemeters (TLD-200) for the measurement of natural outdoor gamma radiation background and by the gamma spectrometry technique on soil samples to determine natural radioactivity in Centro Experimental Aramar (CTMSP-Brazil) and surroundings, from 1989 to 1997. The Centro Tecnologico da Marinha (CTMSP) is a military research organisation, located in Sao Paulo city (Brazil), whose objectives are to develop nuclear and energy systems for Brazilian Naval Ship propulsion. The estimated average outdoor gamma dose rate in air is 405 ± 71 μGy.y-1. The estimated average values obtained for radionuclides of the natural series are 44 ± 6 Bq.kg-1 for 214Pb (238U series), 58 ± 20 Bq.kg-1 for 228Ac (232Th series), and 131 ± 40 Bq.kg-1 for 40K. These values are compared with background values of other places in the world, and indicate a low outdoor gamma dose rate in air and low natural radioactivity in soil samples in Centro Experimental Aramar and region. (author)