Natural radionuclide concentrations in two phosphate ores of east Algeria

Ore is considered as an important source of many elements such as the iron, phosphorus, and uranium. Concerning the natural radionuclides, their concentrations vary from an ore to other depending on the chemical composition of each site. In this work, two phosphate ores found in East of Algeria have been chosen to assess the activity concentration of natural radionuclides represented mainly by three natural radioactive series 238 U, 235 U and 232 Th, and the primordial radionuclide 40 K where they were determined using ultra-low background, high-resolution gamma-ray spectroscopy. The measured activity concentrations of radioactive series ranged from 6.2 ± 0.4 to 733 ± 33 Bq.kg −1 for the 232 Th series, from 249 ± 16 to 547 ± 39 Bq.kg −1 for the 238 U series, around 24.2 ± 2.5 Bq.kg −1 for the 235 U series, and from 1.4 ± 0.2 to 6.7 ± 0.7 Bq.kg −1 for 40 K. To assess exposure to gamma radiation in the two ores, from specific activities of 232 Th, 40 K and 226 Ra, three indexes were determined: Radium equivalent (Ra eq ), external and internal hazard indexes (H ex and H in ), their values ranged from 831 ± 8 to 1298 ± 14 Bq.kg −1 for Ra eq , from 2.2 ± 0.4 to 3.5 ± 0.7 Bq.kg −1 for H ex , and from 4.2 ± 0.7 to 4.5 ± 0.7 Bq.kg −1 for H in .