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The Mayak Production Association was the first Russian site for the production and separation of plutonium. The extensive increase in plutonium production during 1948-1955, as well as the absence of reliable waste-management technology, resulted in significant releases of liquid radioactive effluent into the rather small Techa River. This resulted in chronic external and internal exposure of about 30,000 residents of riverside communities; these residents form the cohort of an epidemiologic investigation. Analysis of the available historical monitoring data indicates that the following reliable data sets can be used for reconstruction of doses received during the early periods of operation of the Mayak Production Association: Temporal pattern of specific beta activity of river water for several sites in the upper Techa region since July 1951; average annual values of specific beta activity of river water and bottom sediments as a function of downstream distance for the whole river since 1951; external gamma-exposure rates near the shoreline as a function of downstream distance for the whole Techa River since 1952; and external gamma-exposure rate as a function of distance from the shoreline for several sites in the upper and middle Techa since 1951. [ABSTRACT FROM AUTHOR]

This paper presents the results of radioecological study of the Iset River and riverside settlements in 1961-2002. In 1961, specific activity of 90Sr in the Iset River water below the Techa River mouth was 44.4 Bq/l and decreased to 3.2 Bq/l in 2002. Annual Techa River run-offinto the Iset River was, on average, 2 x 10(12) Bq of 90Sr in 2000-2004. Density 90Sr-contamination of floodplain soils decreased downstream the Iset River from 146.1 to 37.1 kBq/m2 near the Iset River mouth. In 1977, 90Sr-specific activity of fish muscles was 18 Bq/kg and decreased to 2 Bq/kg in 2002. An average 90Sr-specific activity in milk in settlements located at distances of 12-26 km from the Techa River mouth was 10.2 Bq/l in 1961 and 1.2 Bq/l in 2001. The rate of 90Sr transfer in chain "floodplain soils --> milk" was 2 x 10(-5) (Bq/l)/(Bq/m2). Annual dietary 90Sr-intake by adult residents of the Iset riverside settlements did not exceed an annual limit of intake in 1964-2002.

A number of radiation accidents occurred at the "Mayak" plutonium production complex (Southern Urals, Russia) in 1950-60s that resulted in environmental contamination of large territories in the Southern and Middle Urals with long-lived radionuclides (90Sr, 137Cs). The results of long-term radiological monitoring were compiled into special databases at the Urals Research Center for Radiation Medicine, which allow the study of 90Sr behaviour in the environment and its accumulation in the human body. Retrospective analysis of the data on postmortem measurements of 90Sr in bones performed on residents of the Urals region over 1957-1988 were conducted for the first time. A time-dependence of 90Sr accumulation in the human body upon its density in soils was observed. Age and gender characteristics of 90Sr retention in bones were studied. It was shown that the levels of 90Sr in residents of large territories north and north-east of Chelyabinsk region, and of bordering territories of Sverdlovsk region were several times higher than the average values for the Russian Federation. Based on the measurements the direct dependence of 90Sr content in the skeleton on 90Sr density in soils was observed 30 years after the 1957 accident (the so called "Kyshtym accident"). However, for individual settlements this dependence may be weakened as a result of the influence of different biological and social factors. No influence of gender on 90Sr accumulation in the skeleton was found in the study. The analysis of age characteristics of 90Sr accumulation in bone, as influenced by skeleton growth and maturation, showed maximal levels of 90Sr from global fallout to be accumulated in bones of the persons born in 1949-1955.

A mathematical model is presented for radionuclide migration in a non-running fresh-water reservoir that takes into account removal of microimpurities from water as a result of both molecular and ion exchange sorption at the bottom sediments water interface and detritus formation. The model was tested for sensitivity to precisely estimate experimental parameters. The test showed that the model is universal. Prediction was made of reduction in water of 137Cs and 90Sr contents and distribution of these radionuclides in the water body affected by the accident at the "Mayak" chemical plant.