2002/12/31 by M. Tzortzis, H. Tsertos, S. Christofides +1
Physics and Astronomy · #physics.med-ph #nucl-ex #physics.soc-ph
published as J.Environ.Radioact. 70 (2003) 223-235 · 22 pages including 2 tables and 4 figures; improved text including new references. To appear in Journ. of Env. Radioactivity
arxiv created 2003/02/04 · arxiv updated 2009/12/01
The gamma radiation in samples of a variety of natural tiling rocks (granites) imported in Cyprus for use in the building industry was measured, employing high-resolution gamma-ray spectroscopy. The rock samples were pulverized, sealed in 1 litre plastic Marinelli beakers, and measured in the laboratory with an accumulating time between 10 and 14 hours each. From the measured gamma-ray spectra, activity concentrations were determined for Th-232 (range from 1 to 906 Bq/kg), U-238 (from 1 to 588 Bq/kg) and K-40 (from 50 to 1606 Bq/kg). The total absorbed dose rates in air calculated from the concentrations of the three radionuclides, Th-232 and U-238 series and K-40, ranged from 7 to 1209 nGy/h for full utilization of the materials, from 4 to 605 nGy/h for half utilization and from 2 to 302 nGy/h for one quarter utilization. The total effective dose rates per person indoors were determined to be between 0.02 to 2.97 mSv/y for half utilization of the materials. Applying dose criteria recently recommended by the EU for superficial materials, 25 of the samples meet the exemption dose limit of 0.3 mSv/y, two of them meet the upper dose limit of 1 mSv/y and only one exceeds clearly this limit.