Autor: Vera N. Pozolotina, L. N. Mikhailovskaya, E. V. Degtyareva, E. N. Karavaeva, I. V. Molchanova
Rok vydání: 2002
Předmět:
Zdroj: Russian Journal of Nondestructive Testing. 38:271-277
ISSN: 1061-8309
DOI: 10.1023/a:1020913621780
Popis: The Pu content and distribution in soils of certain territories of the Ural region lo- cated in zones of nuclear accidents and regular operation of power reactor facilities are studied. The maximum content of 239;240 Pu isotopes (up to 5000 Bc/m 2 ) was revealed in soils of the central axis of the East Ural radioactive contamination at a distance of 30 km from the acci- dent point. Regular gas-aerosol releases from the PO \Mayak" plants appreciably contribute to contamination of the neighboring territories. It is shown that almost 10 12 Bc of 239;240 Pu was released in the environment as a result of two nuclear accidents in 1957 and 1967. The nonuni- form terrestrial plutonium contamination (from 200 to 5000 Bc/m 2 ) is noted within the expected central axis of the Totsk radioactive trail. The contribution of the Beloyarsk nuclear power plant to the soil contamination in the fall-out zone of the aerosol emission plume is estimated on the basis of an analysis of the 238 Pu/ 239;240 Pu isotope ratio. Middle and South Ural are the Russian regions in which the nuclear environment is complex. Together with the global radioactive atmospheric falling-outs, the Kyshtym accident at one of the PO \Mayak" plants in 1957, the wind-induced blowing of the bottom sediments from the Karachai lakeside (pond-accumulator of liquid radioactive wastes of the same PO) in 1967, the nonregular discharges of highly radioactive wastes in the Techa river of the Ob'{Irtysh river basin, the explosion of an atom bomb at the Totsk range, and the unprecedented Chernobyl accident signicantly contribute to the formation of the nuclear environment. The regular operation of Ural power reactor facilities also makes a certain contribution to contamination of the environment. Basic relationships of the behavior of the 90 Sr and 137 Cs long-lived radionuclides were mainly considered in radioecological investigations devoted to estimates of consequences of the above- mentioned accidents (1{6). There are much less data (7{9) on the radiation levels of territories of the Ural region due to contamination by such radioactive element as plutonium which is the most dangerous from the viewpoint of radiology. The mass testing explosions of nuclear weapons have formed the level of the global plutonium contamination of the soil-vegetable cover within the limits from 30 to 300 Bc/m 2 (10, 11). In the rst approximation, the contribution of dierent sources to the plutonium contamination of the soil-vegetable cover can be estimated on the basis of the 238 Pu/ 239;240 Pu isotope ratio. It is well known that in the global falling-outs this ratio is of 0.02{0.03 (12). The regular releases of the nuclear reactor, as a rule, are enriched by 238 Pu. In the present study the data characterizing the Pu isotope content and features of the distribu- tion in the soils of zones of nuclear accidents and regularly-operating nuclear power plants in the Ural region are given.
Databáze: OpenAIRE
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