Gamma radiation measurements and dose rates in commercially-used natural tiling rocks (granites).
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 pulverised, sealed in 1-l plastic Marinelli beakers, and measured in the laboratory with an accumulating time between 10 and 14 h each. From the measured gamma-ray spectra, activity concentrations were determined for (232)Th (range from 1 to 906 Bq kg(-1)), (238)U (from 1 to 588 Bq kg(-1)) and (40)K (from 50 to 1606 Bq kg(-1)). The total absorbed dose rates in air calculated from the concentrations of the three radionuclides ranged from 7 to 1209 nGy h(-1) for full utilization of the materials, from 4 to 605 nGy h(-1) for half utilization and from 2 to 302 nGy h(-1) for one quarter utilization. The total effective dose rates per person indoors were determined to be between 0.02 and 2.97 mSv y(-1) 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(-1), two of them meet the upper dose limit of 1 mSv y(-1) and only one clearly exceeds this limit.
Tzortzis
Michalis
M
Department of Physics, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus.
Tsertos
Haralabos
H
Christofides
Stelios
S
Christodoulides
George
G
D003252:Construction Materials; D004781:Environmental Exposure; D005720:Gamma Rays; D008422:Materials Testing; D011868:Radioisotopes / Q000032:analysis; D012016:Reference Values; D012449:Safety; D012822:Silicon Dioxide
D011868:Radioisotopes; C007886:granite; D012822:Silicon Dioxide