Technical Report Evaluation and study of radon occupational exposure levels in dams: a case study of the Gallery of Medau Zirimilis Dam (Sardinia, Italy)

Abstract

Protection of people from radon exposure in workplaces is an important factor in decreasing lung cancer risk. International authorities have set ‘reference levels’ to control enhanced radon exposure. Radiometric investigations, including in-situ radon measurements and laboratory gamma-spectroscopy, were carried out to monitor the radon exposure and define the radon transfer model in the workplaces of Medau-Zirimilis Dam in Sardinia. It was found that a shale formation is the main source of radon accumulated in the gallery of this dam. The water passing through the bedrock transports a considerable amount of sediments containing uranium-bearing minerals. Outgassing of radon from water flowing in the drainage canal and its accumulation due to poor ventilation could be the main reasons for the enhanced indoor radon level. The methodology introduced here can be adopted in underground workplaces like mines and tunnels to understand the natural radiation hazard and the effectiveness of the possible mitigation strategies.