Distribution coefficients of 226Ra and 227Ac on soils and tuff have been obtained by a batch method. The distribution coefficients of Ra on loam, two kinds of sand and tuff were 28m3/kg, 0.45m3/kg, 0.19m3/kg and 1.9m3/kg, respectively. A linear relationship between the distribution coefficients of Ra on each soil and Cation Exchange Capacity(CEC) of each soil was obtained to suggest cation exchange sorption reaction of Ra2+ on soil surface. Sorption-migration behavior of Ra in sand column has been studied. Most of Ra remained in the column after passing of 5,000 pore volume of the column, showing several times the distribution coefficients of Ra than that by the batch method. The distribution coefficients of 227Ac on the soil samples were in the range from 1m3/kg to 10m3/kg.
Differences of the migration behavior and desorption process for radionuclides (6°C o, 85 Sr and 137 Cs) in aerated sandy soil layer were studied by sprinkle of distilled water into the contaminated soil with above nuclides in column. Influence of difference desorption process on radionuclide migration was examined by changing the volume of distilled water sprinkled like rain on the contaminated soil. Quantity of sprinkled water affected the concentration distribution of each radionuclide in soil layer. Each nuclide migrated deeper in the layer according to the increase of water amount, and especially, migration behavior of 85 Sr was remarkably influenced by water amount. It is observed that as to 85 Sr maximum contamination part in soil layer moved to deeper layer with increase of water amount, and that, as to 6°C o and 137 Cs, it moved almost never. On the other hand, activity concentration of 6°C o or 137 Cs in effluent was rather high (10-6 pCi/ml) compared with that of 86 Sr, which could not be detected therein.
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