Modelling of the transformation of speciation processes of Chernobyl origin 137Cs and 90Sr in the soil and in bottom sediments

The paper presents the results of systematic studies of physical and chemical processes associated with the behaviour of Chernobyl origin 137Cs and 90Sr in soil and water. The short term behaviour of radionuclides is governed by the ratio of the speciations in the fallout, which differs significantly for different regions. The long term behaviour of radionuclides is controlled by leaching of fuel particles in the zone around the nuclear power plant and by transformation of radionuclide speciations in the soil in water bodies. A scheme for transformation of radionuclide speciations is proposed. Rate constants for the relevant physico-chemical processes have been obtained for different conditions. Major environmental parameters controlling migration characteristics of radionuclides are identified. A procedure for estimating the distribution coefficient Kd is recommended. (author). 16 refs, 2 figs, 2 tabs