Investigation on radiation attenuation properties of natural stone samples traded in Turkey.

Although radioprotection is globally regulated for high radiation exposure, formal guidelines concerning natural radiation exposure that causes stochastic radiation effects have not been established. The commonly used absorbers lead, tungsten and bismuth are not appropriate for the radioprotection of the public. The primary barrier against natural radiation is the structural components of buildings, where humans spend approximately 80 % of their lifetime. Natural stones are secondary materials, which are applied to walls and floors as coating. This study focuses on the radiation shielding properties of natural stones. Herein, the samples of marble, granite and sedimentary rock traded in Turkey were examined to determine whether they can serve as passive or alternative radioprotection materials. Notable gamma absorption rates were obtained when an intense gamma source with an energy of 662 keV was used. The calculated mass attenuation coefficients were comparable with those of copper and aluminium. The mean mass attenuation coefficient was 0.082 cm/g for marbles and granites and 0.080 cm/g for sedimentary rocks. Considering the stochastic effects, the use of the natural stones as construction materials is anticipated to significantly reduce the natural radiation level in inhabitable regions. Furthermore, natural stones can be used in clinics as secondary radiation shields against low-energy gamma and x-rays.