Assessment of Terrestrial Gamma Radiation in Sinnar State

Abstract

The absorbed dose rate in air at the height of 1 m above ground level was calculated from activity concentrations of gamma-emitting radionuclides in arable soil samples collected from eight locations within Sinnar State using DRCFs. Measurements were carried out using high resolution gamma-spectrometry. Results have shown insignificant variation in activity concentrations of Ra-226, Th-232, and K-40. They all lie within the range of 25-50 Bq/kg for Th-232, 12-20 Bq/kg for Ra-226, and 148-170 Bq/kg for K-40. Average values were 38.01± 8.21 Bq/kg (Th-232), 17.21±2.41 (Ra-226), and 177.44±19.08 Bq/kg for K-40. The average value obtained here for Th-232 is slightly higher than the corresponding world-average. Location-wise comparison revealed that the activity concentration of Cs-137 in soils of Senga and Al-ShiKh Talha is one order of magnitude higher than other locations. However, the values are typical of fallout and indicates that Sudan is unaffected by the latest accident at Chernobyl. The estimated total absorbed dose in air at a height 1m for all sampled locations was found to range from 31-47 nGy/h with an average value of 38.08±7.02 nGy/h which is characteristic of normal background radiation areas. The corresponding annual effective dose equivalent was 47.59± 6.07 Sv/y.