Abstract
Aim: The aim of this article is the presentation and evaluation selected of raw and building materials in terms of radiology.
Introduction: The systematic research of the natural radioactivity of raw and building materials has been conducted in Poland since 1980. Basing on the results of these studies, carried out by both the Central Laboratory for Radiological Protection (CLOR) and over 30 other research laboratories in our country, the national database of natural radioactivity measurements has been set up. The database is supervised by the CLOR and contains the results of the measurements for more than 42 000 samples analysed since 1980 up till now. Due to the economic development of the country, since 1990 there has been an increase in the number of the natural radioactivity measurements of raw and building materials.
Methodology: In Poland the possibility of using different raw and ready building materials is classified due to the value of activity coefficients f1 and f2. Activity coefficient f1 specifies the content of natural isotopes in a test material and is the coefficient of the gamma radiation exposure to the whole body. Activity coefficient f2 specifies the content of radium 226Ra (mother of isotope 222Rn) in the test material and is the coefficient of the exposure of the lungs epithelium to the alpha radiation emitted by the decay products of radon, breathed into with air by the human respiratory system. Activity coefficients are described by the natural radioactivity of potassium 40K, radium 226Ra and thorium 228Th. Activity concentration of these radionuclides is determined by the MAZAR analyser with a scintillation detector. It is a three-window analyser, which measures samples in the range from 1.26 MeV to 2.85 MeV.
Results: This paper shows the values of activity coefficients f1 and f2 for a few selected raw and building materials like ash, concrete, cement and ceramics. Additionally, activity coefficients f1 and f2 for carbon are discussed. Carbon, as a precursor to a few building raws, (ash, slag, mixture of ash and slag) has been measured in significant amounts since 1996. Average value of its activity coefficient f1 was between 0.15 and 0.43 while an average index f2 was from 14.7 Bq/kg to 44.2 Bq/kg for results collected in 1980-2012. Average values of activity coefficients f1 and f2 for carbon are the lowest of all measured and compared materials described in this paper. Average value of activity coefficient f1 of ash as a by-product of coal combustion is a few times higher than for carbon and is higher than the limit value equals 1.0 for results from almost all years.
Conclusions: In the paper, average value and range of dose rate for these several raw and building materials have been shown. An average dose rate is between 31.8 nGy/h for carbon up to 140.8 nGy/h for ash
Keywords: building materials, natural radioactivity, 40K, 226Ra, 228Th
Type of article: original scientific article