Distribuição da concentração de radônio em residências e outras construções da Região Metropolitana de Belo Horizonte - RMBH

• Ano de defesa: 2010
• Autor(a) principal: Talita de Oliveira Santos
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: região metropolitana; concentração de radônio; Tecnologia nuclear
• Link de acesso: http://hdl.handle.net/1843/MBAM-84RMXQ

Human beings are exposed to ionizing radiation from many natural sources. Radon and its progeny have been recognized as the most important contributors to the natural radioactivity dose, accounting for about half of all human exposure to ionizing radiation. Radon is a -radioactive noble gas derived from the natural series of uranium and thorium, which occurs in a wide concentration range in all geological materials, especially, in rocks, soils and waters. By diffusion and convection, radon migrates from the rocks and soils to atmosphere and through fissures, pipes and holes it may enter the dwellings and other buildings. Another important radon source in dwellings is its emanation from the construction material. The radon progeny concentration in dwellings has been receiving considerable global attention due to its potential effect in causing lung cancer if it deposited in upper respiratory tract when inhaled. This work presents radon concentration distribution in dwellings in Metropolitan Region of Belo Horizonte RMBH. The geological settings of the area are Archean rocks of Granitic Gneissic Complex and of metasediments sequences of the great Precambrian unit of the Iron Quadrangle of Minas Gerais, Brazil. Radon concentration measurements were carried out with continuous detector AlphaGUARD PQ200PRO (Genitron), in passive mode and with passive detectors E-PERM Electrets Ion Chamber-EIC. The radon progeny concentration was carried out with a solid state alpha spectroscope, the DOSEman PRO (Sarad). It was found an indoor radon concentration varying in a large range from 4 to 2664,0 Bq.m-3, with an average value of 108.0 Bq.m-3, median of 70 Bq.m-3, geometric mean equal to 76 Bq.m-3 and standard deviation of 170 Bq.m-3. About 15% of the results are over the United States Environmental Protection Agency (U.S. EPA) actions level, which is 148 Bq.m3. The equilibrium factor between radon and its progeny were determinated in dwellings, as 0.3 in average. The mean effective dose estimate for the RMBH inhabitants is about 2, 0 mSv. The variable results are due mainly to region geological factors and building material composition of dwellings.