| Popis: |
The presence of some enterprises of the nuclear fuel cycle (NFC) in the Ural region has caused the formation of a radioactive contamination on large territories that exceeds the level of global fallouts typical for the middle latitudes of the Northern Hemisphere. Currently, additional sources of man-made radionuclides in the Urals are (1) the operating NFC enterprises, the largest of which are “Mayak” Production Association and Beloyarsk Nuclear Power Plant (permissible emissions), and (2) contaminated zones that are sources of secondary pollution of the environment. The activity of PA “Mayak” created the most problematic areas: the Techa River, which was polluted with liquid radioactive wastes, and the East Ural Radioactive Trace (EURT), which was the result of the Kyshtym accident of 1957. These local zones possessed very high levels of radionuclides, including 90Sr. The inventory of 90Sr reached 70,000 kBq/m2 in the EURT head part. Prolonged input of global fallout and gas-aerosol emissions from the NFC enterprises and transport of radionuclides from contaminated areas supported during a long time stable global (1.3 Bq/m2) and regional (1.6–3.0 Bq/m2) levels of 90Sr in the Urals. Migration of 90Sr within geochemical conjugations depends on the sources of intake (gas-aerosol emission or liquid discharges) of the radionuclide into the environment. The depth of vertical migration and the character of the distribution of the radionuclide depend on the regime of moistening and the type of soils. |
