Simulation of Dose Assessment for Special Environmental Radioactivity Distribution Using Monte Carlo Technique

Abstract

Many researchers use the estimation method of exposure doses due to natural radioactivity adopted by UNSCEAR equation, which is based on an infinite plan source modeling. The results in most cases are acceptable within acceptable accuracy and error. However, in many cases, this ap-proach cannot be applied e.g., for more complicated source geometry, composition, radioactivity distribution and so on. In previous situations, simulation and modeling are needed for exposure dose calculation to get more acceptable and accurate results. In the present work, modeling and recalculation of exposure dose rate are performed for an important previous published study about Hammam Pharaon. The study is selected because of its special physical characterization parameters and possible effects on Egyptian tourism. The effects of radionuclides distribution with soils and source composition, density, and geometry as recommended by NCRP 129 have been taken into consideration. The results for depth profile calculation show the conformation with the NCRP 129, which indicates a reduction in the free air exposure dose due to the fact that the above soil covered the active slab by 20% -25% for 1 cm cover-up to 95% -100% for 30 cm cover. In addition, the effect of density variation in dose rate is studied. A comparison with pre-vious results has been performed.