Assessment of radiation hazard indices due to natural radioactivity in soil samples from Orlu, Imo State, Nigeria

The use of a Radiation Alert Inspector device and a gamma-spectrometry system fitted with a Sodium Iodide (NaI) detector was used to determine the radioactivity concentration level of natural radionuclides U-238, Th-232, and K-40 in soil in several locations in Orlu, Imo State, Nigeria. 19 soil samples were collected for analysis from several locations of factories, agricultural farming-lands, gullies and water eroded areas, and soil deposits very close to flowing waters from rocks, due to environmental concerns arising from human activities in this region. The activity concentration values for U-238, Th-232, and K-40 were found to range from 0.14 to 9.34 Bq.kg(-1), 0.03 -3.75Bq.kg(-1), and 16.83 -783.06 Bq.kg(-1), respectively, with average mean values of 4.15, 1.64, and 134.13 Bq.kg(-1). Radium equivalent activity, absorbed dose rate, and gamma index mean values for the samples were 16.822 Bq.kg(-1), 8.528 nGyh(-1), and 0.133 mSv respectively, the obtained values were below the safe limit values set by the United Nations Scientific Committee on the Effects of Atomic Radiation of 370.0 Bq.kg(-1), 59.0nGyh(-1), and 1.0 mSv. According to the findings, the regions under study are reasonably safe for human outdoor activities such as agriculture, construction, and factory operations.