Electrokinetic Removal of Radionuclides

A number of serious problems occur in the process of atomic energy enterprises operations that are related to the pollution of certain sites with radioactive materials. The sources of the radioactive contamination of soils are the sites where different atomic objects are located, for example, plants for processing of nuclear wastes, atomic power plants, plants for the production of nuclear fuel and nuclear reactors, and others. Radioactive contamination enters into the soils as a result of different emergencies concerning the storage, transport, and use of nuclear fuel or nuclear waste. Nuclear tests were important and dangerous sources of the entrance of radioactive contamination into the environment prior to their prohibition across the world. 

The principal among radioactive materials are the following isotopes °Co, °Sr, °Y, ° Ru, Cs, Ce, Pm, 238,239,240py Ra, and so on. The groups of toxic radioactive elements are presented in Table 5.1. Approximately 95% of radioactive pollutants are concentrated in the upper soil layer. Individual radioactive nucUdes are present in the soil in different forms. Depending on the soil composition, 8%-30% of radioactive nuclides are present in exchange forms, 2%-10% of them are in water-soluble forms, and 60%-85% in tightly bounded forms (Table 5.2). 

Bednar et al (2004) describe the processes affecting thorium mobility in semiarid soil, which has implications for future remedial action. Aqueous extraction and filtration experiments have demonstrated the colloidal nature of thorium in the soU, due in part to the low solubility of thorium oxide. Colloidal material was defined as that removed by a 0.22-/jm or smaller filter after being filtered to a nominally dissolved size (0.45/rm). Additionally, association of thorium with natural organic 

Electrochemical Remediation Technologies for Polluted Soils, Sediments and Groundwater, Edited by Krishna R. Reddy and Claudio Cameselle Copyright 2009 John Wiley Sons, Inc. 

A Particularly high 210pb 210pp 226 228rpb 232Xh, Np, PU, PU, Am, 

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On the Russian territory, some lands in the Urals and in Siberia are also contaminated by radionuclides. In the Ural region, heavily contaminated soils can be found along the valley of the river Techa (Fig. 5.7). Significant territory is contaminated by radionuclides around the manufacturing association Mayak (Table 5.6). Electrokinetic removal of the radionuclides on these territories is very urgent. 

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