Natural radioactivity and the resulting radiation doses in some kinds of commercially marble collected from different quarries and factories in Egypt

Abstract

Fourteen samples of marble were collected from different factories in Egypt. The samples were crushed, dried in controlled furnace for around twenty four hours, and then stored for five weeks in plastic Marinelli beakers. Concentrations and the U- and Th-bearing minerals were studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS).The gamma radiation of the samples was measured, employing high resolution γ-ray spectroscopy with an accumulating time for about 80000 sec. each. From the measured γ -ray spectra, activity concentrations were determined for marble samples 226 Ra (37. 6 ± 1.7 - 100.54 ± 3.2 Bq/kg), 232 Th (3.57 ± 0.64 - 9.37 ± 1.80 Bq/kg) and 40 K (30.68 ± 1.1 – 1196 ± 4.9 Bq/kg). The absorbed dose rates, annual effective dose rates, radium equivalent activities as well as the radiation hazard indices were estimated. The radium equivalent activities (Ra eq ) are lower than the limit of 370 Bq kg?1 set by the Organization for Economic Cooperation and Development (Exposure to radiation from the natural radioactivity in building materials. Report by a Group of Experts of the OECD, Nuclear Energy Agency, OECD, Paris, 1979) [1]. All obtained results referred to the fact that all the concentrations were within the allowed limits to domestic use. Comparing the results in this work with those published by International Atomic Energy Agency and local and universal researches, it was found that these concentrations were within the allowed limits for agricultural and domestic uses.