Natural Radionuclides Abundance in the Region of Buhovo Uranium-Mines

The object of this study is the content of natural radionuclides in the of uranium mines and the adjacent meadows located between the towns Buhovo and Seslavtsi in the southern slopes of Murgash branch of the Balkan Mountains and the foothills of the peak Goten. The interest of this region is due to the fact that there is the highest number of mine heaps in the country located (over 200, with approximately 5 million m3 rock with total activity about 19 TBq), the result of almost half a century of exploitation of the uranium mines of Buhovo and Seslavtsi. The content of natural radionuclides in samples, taken directly from the heaps, from the shtolns, from the shafts and from the tailing, as well as in samples taken from soil of the adjacent meadows has been studied in the present work. Measurements were made using the gamma-spectrometric systems in the Laboratory of Nuclear Physics and Radioecology of Shumen University "K. Preslavski”and in the Institute for Nuclear Research and Nuclear Energy-BAS . It was found that the content of natural radionuclides in samples from selected locations near the area of mines Buhovo generally does not exceed the corresponding limits accordingly to the regulation norms issued by the Bulgarian Council of Ministers in 2004. The specific activity of 238U in the samples taken from the old and the new repositories indicates that its content is in quantities exceeding the limits. The specific activity of 238U measured in mine heaps for some samples significantly exceeds the norm. The specific activity of 232Th in the samples taken from Shtoln 93, from Shtoln heap of shaft 32 and "Chora" are 1,5 to 2,5 times the values. In the samples from outside the area of mines high levels of 232Th have not been observed. The measured specific activity of 40K in all samples was within the normal limits.