Corresponding author: sfares2@yahoo.com DOI: 10.21608/ajnsa.2019.6648.1153 © Scientific Information, Documentation and Publishing Office (SIDPO)-EAEA Arab J. Nucl. Sci. Appl., Vol. XX, X, 1-9 (2019) Natural Radioactivity Measurement of Bricks Used in the Building Materials of Egypt S.Fares (1,2) , H.A.Yakout (3) 1 Department of Radiation Physics, National Center for Radiation Research and Technology NCRRT, Atomic Energy Authority, Cairo, Egypt. 2 Department of Physics , Faculty of Science, Baha University, Saudi Arabia 3 Department of Physics, Faculty of Science, King Khalid University, Abha, Saudi Arabia Percentage and radionuclides content in the brick material used in construction depend on the origin and the geological condition of the source material. Bricks used as building materials in Egypt were manufactured from clay and rocks extracted from deposited sediments of Nile River. The aim of the study was to determine the radiation activity resulting from a different kind of bricks used in the construction process in Egypt. In the present work, 20 samples of three types of bricks, clay brick (CB), making facade brick (MFB) and firebrick (FB) were selected from different regions and plants in Egypt. The activity concentration of 226 Ra, 232 Th and 40 K in many brick under investigation were measured using gamma ray spectroscopy system. Results showed that, the radium equivalent concentration (Raeq) calculated and compared well with the world reported values. As shown in the results, the mean values of radioactivity concentrations of 226 Ra, 232 Th and 40 K for CB bricks, which represent the highest ??? in many bricks in the present study with values (39, 38 and 199 Bq/kg), respectively. Radium equivalent activities calculated for many bricks in the study???. The average values of radium equivalent activities 110, 88 and 83 Bq/kg, for bricks type were found to be below the global level of 370 Bq/kg of building materials.The maximum values of Ra eq calculated for all studied samples were found to be 152.79 Bq/kg for (CB4) sample, 112.0 for (MFB10) sample, and 118.77 Bq/kg for (FB20) sample. To test the radiological hazard of the natural radioactivity, the potential radiological hazards were assessed by calculating the indoor absorbed gamma dose rate (DR), the annual effective dose rate, outdoor and indoor (Deff), the alpha index (Iα), the gamma index (Iγ), and the external hazard (Hex) and internal hazard (Hin) indices. Considering that the values of the risk indicators were lower than the recommended levels, we have concluded that the buildings constructed from these brick samples in our study are safe for the population. Keywords: Brick, Radioactivity, Health hazard indices, Radium equivalent, HPGe. Introduction Radiation background is one of the active environmental factors that are very significant in a human’s life. It is important to show population exposures in buildings resulting from natural radioactivity in building materials, which a source of exposure to indoor radiation. The appoint of 226 Ra, 232 Th and 40 K content in building materials is the main concern indoor radiation in dwellings which produces significant internal and external dose rates in nGy/h [1,2]. So, the activity concentration of these radionuclides measured by researchers in various building materials in different countries of the world such as in Egypt [3-8], for different fabricated types of bricks (clay, cement, and sand) and used in buildings in Cairo region in Egypt [9]. ISSN 1110-0451 (ESNSA) Web site: ajnsa.journals.ekb.eg Arab Journal of Nuclear Sciences and Applications Received 13 th Dec. 2018 Accepted 19 th May 20 19