Distribution and disequilibrium of natural radionuclides in the black shale from Wadi Naseib area, Southwest Sinai, and their environmental hazard indices

Several radionuclides of the 238U (or its decay daughters such as 234Pa, 234U, 230Th, 226Ra, 214Pb, and 214Bi), 232Th (228Ac, 208Tl, and 212Bi), and 235U decay series have been measured. The 234U/238U activity ratios (ARs) are >1 for most rock samples indicating preferential abundance of 234U relative to 238U from the rock due to prevailing reducing conditions. The 226Ra/238U ratios are ranging between 0.04 and 0.6 and averaging 0.4 which show disequilibrium in the direction of uranium concentrations. 230Th/238U and 230Th/234U ARs for all studied samples are less than unity, suggesting that all 230Th are produced by in situ decay of 234U and there is no allogeneic or initial 230Th. Exposure rate, dose rate, radium equivalent activity, external hazard index, internal hazard index, and radioactivity level index are determined

Natural Radioactivity Assessment and Radiation Hazards of Pegmatite as a Building Material, Hafafit Area, Southeastern Desert, Egypt

Sixty-seven sites of Hafafit pegmatite from the Southeastern Desert of Egypt were investigated radiometrically in the field using an in situ γ-ray spectrometer to determine eU, eTh, and K contents. The obtained results ranged from 0.4 to 6 ppm for eU with a mean value of 2.5 ppm, from 0.2 to 32 ppm for eTh with a mean value of 6.7 ppm, and from 0.7% to 5.4% for K with a mean value of 3.3%. Consequently, the radiological effects from these rocks were estimates by determination of the environmental parameters: gamma activity concentration index Iγ, external hazard index Hex, internal hazard index Hin, external absorbed dose rates in outdoor, and external absorbed dose rates in indoor air. The results obtained in this study showed that values U, Th, and K lie in the range of the acceptable world values. In addition, the calculated radiation hazard parameters (Iγ, Hex, and Hin) have values lower than the world values, while the calculated external absorbed dose rates (Dair) have values higher than the world and Egyptian permissible levels