E. Svoukis | Searcharxiv

arXiv2006

Indoor and Outdoor in Situ High-Resolution Gamma Radiation Measurements in Urban Areas of Cyprus

In situ, high-resolution, gamma-ray spectrometry of a total number of 70 outdoor and 20 indoor representative measurements were performed in preselected, common locations of the main urban areas of Cyprus. Specific activities and gamma absorbed dose rates in air due to the naturally occurring radionuclides of Th-232 and U-238 series, and K-40 are determined and discussed. Effective dose rate to the Cyprus population due to terrestrial gamma radiation is derived directly from this work. The results obtained outdoors match very well with those derived previously by high-resolution gamma spectrometry of soil samples, which were collected from the main island bedrock surface. This implies that the construction and building materials in urban areas do not affect the external gamma dose rate; thus they are mostly of local origin. Finally, the indoor/outdoor gamma dose ratio was found to be 1.4 +- 0.5.

physics.med-ph↗

arXiv2004

A Comprehensive Study of Natural Gamma Radioactivity Levels and Associated Dose Rates from Surface Soils in Cyprus

A survey was carried out to determine activity concentration levels and associated dose rates from the naturally occurring radionuclides Th-232, U-238, and K-40, in the various geological formations appearing throughout the geographically accessible area of Cyprus, by means of high-resolution gamma-ray spectrometry. A total number of 115 representative soil samples were collected from all over the bedrock surface of the island, based on the different lithological units of the study area, sieved through a fine mesh, sealed in 1000-mL plastic Marinelli beakers, and measured in the laboratory with respect to their gamma radioactivity for a counting time of 18 hours each. From the measured spectra, activity concentrations were determined for Th-232 (range from 1.0x10^-2 to 39.8 Bq/kg), U-238 (from 1.0x10^-2 to 39.3 Bq/kg) and K-40 (from 4.0x10^-2 to 565.8 Bq/kg). Gamma absorbed dose rates in air outdoors were calculated to be in the range of 1.1x10^-2 - 51.3 nGy/h, depending on the geological features, with an overall mean value of 8.7 nGy/h and a standard deviation of 8.4 nGy/h. This value is by a factor of about 7 below the corresponding population-weighted world-averaged value of 60 nGy/h reported by UNSCEAR (2000), and one of the lowest that has been reported from similar investigations worldwide. Assuming a 20% occupancy factor, the corresponding effective dose rates outdoors equivalent to the population were calculated to be between 1.3x10^-2 and 62.9 micro Sv/y, with an arithmetic mean value of 10.7 micro Sv/y and a standard deviation of 10.3 micro Sv/y.

physics.med-ph↗