Evaluation of External Beta Absorbed Dose for Contamination of the Skin

Abstract

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.