Determination of natural radioactivity in building materials used in the south-eastern area of Macedonia by γ-ray spectrometry

The average indoor-absorbed dose rate in air from terrestrial sources of radioactivity is estimated to be 70 nGy h-1. Elevated external dose rates may arise from high activities of radionuclides in building materials. Large-scale surveys of the concentrations of radioelements in construction materials were summarized in the reports of the United Nations. The presence of the naturally occurring radionuclides 40K, 238U, 232Th and their daughter products in building materials is a source of indoor radioactive pollution. Samples of sand and manufactured building materials collected from the region of south-east Macedonia have been analyzed for the primordial natural radionuclides 238U, 232Th and 40K using γ-ray spectrometry. The specific activities of these radionuclides in the samples are compared with those of the world averages for soil. The comparison shows that, of seven analyzed samples, only three brick samples have higher activities than the world averages for soil. The specific activities in these materials, having a radium equivalent activity of less than 370 Bq kg-1 when evaluated for radiological effects, show that all materials meet the external γ-ray dose limitation of 1,5 mSv y-1. [Original)