Radioactive Concrete Sources for Calibration of Uranium Exploration and Environmental Field Instruments Constructed at IRD/CNEN (Instituto de Radioprotecao e Dosimetria, Brazilian Nuclear Energy Commission)

摘要

A radiometric calibration system constructed at the Instituto de Radioprotecao e Dosimetria (IRD) of the Brazilian Nuclear Energy Commission (CNEN) to be used by geophysicists interested in uranium exploration and scientists working with natural radioactivity and environment is described. The system consists of 8 radioactive concrete sources. The sources are of cylindrical shape with 3m diameter and 0,5m thickness weighting approximately 7.5 tonnes. Uranium, thorium and potassium ores were added to the concrete under conditions to achieve perfect homogenization. One hundred four samples were collected and analysed by eight laboratories. In addition, in-situ radiometric grade determination were performed with calibrated instruments. U, Th and K reference values were then assigned to each source. The system also has a 4m diameter water pond for cosmic-ray and instrument noise corrections. (Atomindex citation 17:089883)