Dispersion of radon in the atmosphere around old uranium mill tailings

This paper presents the results of investigations of radon levels in the atmosphere around old uranium tailings aiming to estimate the influence of inactive uranium sites to the population and personnel. These tailings are situated in the area of a former uranium processing activity of a Pridniprovsk Chemical Plant in the city of Dniprodzierzhinsk. The radon-222 measurements have been carried out using an etched track system TRACK 2010Z. The minimum detectable activity of radon-222 has made up 2 Bq/m3 with the exposure of 30 days. Corresponding data sets of radon-222 and its daughters have been analysed. We have calculated distribution of the radon equilibrium factor (F), i.e. the ratio between radon and radon daughters for the investigated site. Our study shows a contrast spatial radon-222 dispersion in the atmosphere, while radon-222 is lowered to the background levels. The average value of the F makes up 0.146 for the undisturbed open atmosphere. Atmospheric inversions cause a significant rise of F that goes up to 0.487. The present research has been carried out within the frameworks of the STCU project no. 3290.