Skin dose is very difficult to be measured directly and is usually estimated. The beta dose rate to the skin expressed in terms of the average surface concentrations of a radionuclide on the skin gives more reliable estimates for this exposure pathway. However, the data in the literature vary as much as an order of magnitude. In this study, external beta-ray dose rate for human skin contamination around an isotropic point source of mono-energetic electrons is calculated. The beta-ray doses rates were computed by performing analytical integration of a semi-empirical point dose rate function. Evaluation of the model is realized by calculating the dose rate for the contamination of the skin at different depths for samples of air collected around the Research Reactor located at the Atomic Energy Authority (Egypt). Meandering of the plume i.e., low wind condition is taken into consideration. The above mentioned treatment is applied for different meteorological states, namely different thermal stability classes, A,B,C,D and E. The maximum beta absorbed dose for the contamination of the skin is for stability class E for nuclide of Cs 137 at depth of 20 m from the skin. The results were compared with those previously reported and it was found that some of the present results agree precisely with previous investigations.
The method of Laplace Adomain Decomposition has been used to obtain a semi-analytical solution of the threedimensional steady state advection diffusion equation for dispersion of air pollutant from a point source. The present treatment takes into account a realistic boundary condition which considers the ground surface as an absorberreflector surface for the pollutant, simultaneously. This physical consideration is achieved by assuming that the vertical eddy diffusivity coefficient should be non-zero at the ground surface for vertical diffusion to be possible. The wind prevailing speed is parameterized in terms of vertical height using the power law profile. An upper boundary condition assuming capping inversion is considered which means that pollutant is subjected to a boundary Condition of zero flux. The present model calculations are compared with the available data of the atmospheric dispersion experiments that were carried out in the Copenhagen area (Denmark) and the semi-empirical model for Gaussian plume model with the same input data. In both comparison tasks, the results are reasonably good which indicates that the present treatment performs well as a simple analytical dispersion model.
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