Radioactive Rock Dumps in the Elkon Uranium Ore Area (South Yakutia)

We examine the geographical features in the distribution and the radiation parameters of radioactive rock dumps in the Elkon uranium ore area on the territory of South Yakutia. It is pointed out that the dumps under study are geomorphologically located on the Elkon horst which is a protrusion of crystalline basement rocks, towering over the territory of the Aldan highlands. It is found that most of these dumps lie within streambeds and in the bottoms of mountain rivers of the zone of hypergenesis and, geochemically, they are influenced by steep-slope topography, a cold humid climate and mountain-taiga vegetation dominating land cover. It is shown that these rock dumps were formed in the last third of the 20th century, during a large-scale and intense geological exploration for radioactive raw materials in this area. Radiation parameters of the dumps under study, such as the gamma radiation exposure dose, the content of 238U, 232Th and 40K, as well as the effective specific activity of these radionuclides were determined. It is found that the most active rock dumps, in their radiation parameters, approach radioactive ores. The dumps under study were ranked according to the degree of radiation danger to the population on the basis of the particular values of the gamma radiation exposure dose and effective specific activity of these radionuclides. It is established that the main source of radioactive contamination of soil and vegetation cover and the surface waters in the Elkon uranium ore area on the territory of South Yakutia are 40 rock dumps which are unevenly distributed in the total area of about 500 km2 of the mountain-taiga permafrost landscapes. It is determined that more than half of these dumps, in their radiation parameters, are classified as hazardous and specially hazardous.