International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The basic radionuclides that cause natural radiation – potassium, uranium, radium, thorium, radon, thorom. Is described their content in different soils and rocks, as given more attention to potassium because it is the most widespread in the earth’s crust and its influence is strongest. An analysis of radiological monijoring of soils in Bulgaria in the past two years, which show that there is no deviation from the normal background values.