Soils are naturally radioactive, because of their mineral content. An effective dose delivered by photon emitted from natural radioactivity in soil （40K, 23SU and 232Th and their progenies） was calculated in this wo...Soils are naturally radioactive, because of their mineral content. An effective dose delivered by photon emitted from natural radioactivity in soil （40K, 23SU and 232Th and their progenies） was calculated in this work. Calculations were performed using the ORNL （Oak Ridge national laboratory） human phantom and Monte Carlo N-particle transport code MCNP-4C according to ICRPI03 recommendations. Optimum dimensions of each source were determined considering the incident photon energy. Then, these dimensions were employed in the MCNP code input for calculation of conversion factors which relate the effective dose rate and activity. The obtained factors of the 238U series, 232Th series and the 4~K in soil are 0.383, 0.314 and 0.019 nSv h-~ per Bq kg~, respectively. These results were compared with other studies and revealed that there is a good agreement exists between two sets of data. The estimation of the effective dose rates and the annual effective dose for the adult population has been derived in different regions of Iran, considering the natural radioactivity distribution in soil samples from these regions. Finally, the obtained results in this study were compared with UNSCEAR （United Nations Scientific Committee on the Effects of Atomic Radiation） 2008 report.展开更多
文摘Soils are naturally radioactive, because of their mineral content. An effective dose delivered by photon emitted from natural radioactivity in soil （40K, 23SU and 232Th and their progenies） was calculated in this work. Calculations were performed using the ORNL （Oak Ridge national laboratory） human phantom and Monte Carlo N-particle transport code MCNP-4C according to ICRPI03 recommendations. Optimum dimensions of each source were determined considering the incident photon energy. Then, these dimensions were employed in the MCNP code input for calculation of conversion factors which relate the effective dose rate and activity. The obtained factors of the 238U series, 232Th series and the 4~K in soil are 0.383, 0.314 and 0.019 nSv h-~ per Bq kg~, respectively. These results were compared with other studies and revealed that there is a good agreement exists between two sets of data. The estimation of the effective dose rates and the annual effective dose for the adult population has been derived in different regions of Iran, considering the natural radioactivity distribution in soil samples from these regions. Finally, the obtained results in this study were compared with UNSCEAR （United Nations Scientific Committee on the Effects of Atomic Radiation） 2008 report.
