Radioactivity of the atmosphere. Radioactive nuclides of cosmogenic origin, of terrestrial origin. Atmospheric dispersion of radioactive nuclides. Radiactiv in marine environment, on rivers and lakes, on tap water, on thermal springs. Radioactivity in soil and plants.Nuclear Energy: uranium, mines, uranium enrichment, depleted uranium, radioactive wastes. Nuclear accidents. Radiactive fallout. Radiation dosimetry