Measurement of Indoor Terrestrial Gamma Radiation Dose and Evaluation of Annual Effective Dose at AECD Campus, Dhaka, Bangladesh

Background: In this study, indoor terrestrial gamma radiation dose rates were measured at the Atomic Energy Centre Dhaka (AECD) Campus within Dhaka University area in Shahbag Thana of Dhaka, Bangladesh. Aim of the study: This kind of study is required to detect the presence of natural and artificial radionuclides (if any) releasing from nuclear facilities in the country or from neighbouring countries. Materials and Methods: The measurement was performed using a portable High Purity Germanium (HPGe) detector (Model No. GEM25P4-83). The portable HPGe detector was placed at 1 meter above the ground facing downward and data acquisition time for each monitoring point (MP) was 10,000 sec. Total 21 monitoring points (MP) were selected for collection of gamma-ray spectrum in the indoor environment at the AECD Campus. The MPs were marked-out using Global Positioning System (GPS) navigation. The GPS reading of the sampling locations were varied from E: 90o23'42'' — 90o23'47.4'' and N: 23o43'49.8'' — 23o43'53.4''. Results: The measured dose rates due to natural radionuclides were ranged from 0.373 µGy.h-1 to 0.646 µGy.h-1 with an average of 0.494 ± 0.0682 µGy.h-1. The annual effective dose to the population from indoor terrestrial gamma radiation was varied from 1.83 to 3.17 mSv. Conclusion: The range of dose rate and annual effective dose due to indoor terrestrial gamma radiation is lower than some European Countries like Italy, Sweden and Czech Republic and higher than India, Iran and Azerbaijan. It was observed that ground floor dose rate is slightly higher than first floor dose rate because accumulation from radon gas near ground surface contributes to the higher gamma absorbed dose rate..