Determination of absorbed and effective dose from natural occurring radionuclide around a superphosphate fertilizer factory in Nigeria

The amount of radioactivity in soils varies widely and man is continuously being exposed to radiation. This study presents result of outdoor absorbed dose rates and estimated effective dose from the soils samples collected from different locations around a superphosphate fertilizer factory in Nigeria. An efficiency and Energy calibrated high purity germanium detector was used to carry out the study while gamma vision software was used for the spectrum analysis. The Activity Concentrations of the soil samples collected from the different locations in the factory ranges from 48.99±7.47 to 520.37±20.46 BqKg-1 for 234U, 55.32±7.59 to 215.18±8.70 BqKg-1 for 232Th, and 101.32±13.34 to 476.04±28.07 BqKg-1 for 40K respectively. The calculated absorbed dose rate and outdoor annual effective dose from the soil samples ranges from 99.18 to 282.55nGy/hr and 0.120 to 0.342mSv/yr respectively. The mean annual effective dose was calculated to be 0.217mSv/yr. The result showed the radiation exposure level from the factory activities to the public is lower than the IAEA recommended value of 1mSv/yr. Hence radiologically the operation of the factory does not appear to pose immediate threat to the factory workers.