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National Technical University of Athens
School of Mechanical Engineering
Nuclear Engineering Department

Proceedings of "INDOOR AIR, An Integrated Approach, International Workshop" , pp. 131 - 134, November 27 - December 1, 1994, Gold Coast, Australia

NATURAL RADIOACTIVITY CONTENT AND RADON EXHALATION RATES OF GREEK BUILDING MATERIALS

A. Louizi and C. Proukakis
Department of Medical Physics
School of Medicine
N.P. Petropoulos, and S.E.Simopoulos
Nuclear Engineering Section
Mechanical Engineering Department
National Technical University of Athens

Greek building materials were analysed for natural radioactivity (Ra-226, Th-232 and K-40) which, according to the results obtained, is low with the exception of a few specimens of cement and clay bricks with Ra-226 concentrations up to 147 and 48 Bq/kg respectively. The radon exhalation rate of the same materials has been evaluated using an air-tight 1m³ steel container. The container environment is conditioned by a heating unit and a humidifier, in order to control temperature and humidity over the range 12-45 °C and 15-99% respectively. A ±50 mbar differential pressure transducer is used for recording pressure changes inside the container, which is also equipped with an aerosol generating system. Radon progeny radiation is continuously monitored in-situ via a 2x2'' Am-doped NaI detector stabilised for spectrum shifts. Furthermore, grab sampling on high efficiency filters analysed using high-resolution gamma and alpha spectrometry is also conducted. The exhalation rate of the above Greek building materials already analysed range between 3-20 ?Bq/(kgs). Moreover, brick walls and concrete slabs constructed using these materials present exhalation rates between 2-3 mBq/(m²s).