[Radiological Aspects of Transition of Russian Areas Affected by the Chernobyl Accident to Normal Activities].

Dynamics of radiation situation in settlements, agriculture and forestry on the Russian Federation areas af- fected by the Chernobyl accident is presented. A set of challenging problems on public radiation protection and rehabilitation of territories was determined. The main objective at a long-term period after the accident is a stage-wise return of the affected areas to normal activity without any radiological criteria restrictions. For practical realization of this process it is necessary to change the national statutes and regulations consid- ering the contemporary international approaches, to pass to the current exposure situation and to establish reference levels, to define criteria of transition of the areas affected after the Chernobyl accident to normal activity. The change of conceptual approaches will allow one to revise the boundaries of settlement zoning and to develop the regulatory framework on procedures of changing their status from radioactively contami- nated zone to normal activity zone; to develop the regulatory framework on the procedures of transition of agricultural and forest lands classified as radioactively contaminated zones to territories where the traditional husbandry is possible. The Russian Federation has positive experience of transition of areas contaminated as a result of the Chernobyl accident to normal activity.

[Revision of parameters of radionuclide migration in agroecosystems].

Results of the project IAEA "Environmental Modelling for Radiation Safety" (EMRAS) on revision of parameters of radionuclide migration in agroecosystems are presented. Methodical approaches to a grouping of the initial information are stated. The databases on parameters of radionuclide transfer in agricultural plants for various climatic zones, and also in system a diet--an organism of an agricultural animal are described. The examples of an estimation of parameters are resulted.

[The dose estimation to the population as a result of radioactive contamination of the Semipalatinsk Test area].

The results are presented from estimation of spatial distribution of 137Cs and 90Sr contamination densities in the areas of horses and sheep grazing within the Semipalatinsk Test Site. Dose burdens to various cohorts of the population living within the STS and consuming contaminated animal products are predicted. Doses of shepherds in the most contaminated pasture areas have been found to exceed the accepted limit (1 mSv/y). The conclusion is made about the need for further studies on the risk assessment of the STS population exposure above the accepted limits.

[Modelling of 137Cs migration in agroecosystems under safety and rehabilitation measures]. / Modelirovanie migratsii 137 CS v agroékosistemakh v usloviiakh provedeniia zashchitnykh i reabilitatsionnykh meropriiatii.

Mathematical model describing dynamics of 137Cs transfer in agroecosystems under rehubilitation measures on arable, haylands, pastures and natural meadow ecosystems is presented. Possibilities of the model application for prediction of the radionuclide content in agricultural production and estimation of efficiency of countermeasures in region of the ChNPP accident are shown.