Significant radioactive contamination of soil around a coal-fired thermal power plant.

Abstract Soil samples were collected around a coal-fired power plant from 81 different locations. Brown coal, unusually rich in uranium, is burnt in this plant that lies inside the confines of a small industrial town and has been operational since 1943. Activity concentrations of the radionuclides 238 U, 226 Ra, 232 Th, 137 Cs and 40 K were determined in the samples. Considerably elevated concentrations of 238 U and 226 Ra have been found in most samples collected within the inhabited area. Concentrations of 238 U and 226 Ra in soil decreased regularly with increasing depth at many locations, which can be explained by fly-ash fallout. Concentrations of 238 U and 226 Ra in the top (0–5 cm depth) layer of soil in public areas inside the town are 4.7 times higher, on average, than those in the uncontaminated deeper layers, which means there is about 108 Bq kg −1 surplus activity concentration above the geological background. A high emanation rate of 222 Rn from the contaminated soil layers and significant disequilibrium between 238 U and 226 Ra activities in some kinds of samples have been found.