Development of vertical electrokinetic-flushing decontamination technology to remove 60Co and 137Cs from a Korean nuclear facility site

Vertical electrokinetic-flushing equipment suitable to the geological characteristics of Korean nuclear facility sites was developed for the decontamination of some real radioactive soil. The optimum reagent and electric current were chosen through vertical electrokinetic-flushing experiments. The effect of the particle size of some soil and the radioactive concentration of some soil on the removal efficiencies of the nuclides from said soil were analyzed. The experimental results are as follows. The removal efficiencies of 60Co and 137Cs by nitric acid were increased by 3.3% and 2.0% more than those by acetic acid. And, moreover, when nitric acid instead of acetic acid was used, it had the advantage of a reduction of the electricity consumption due to its higher electrolytic conductivity. The higher the radioactivity concentration of the soil was, the higher the removal efficiencies of 60Co and 137Cs were. Namely, the removal efficiencies of 60Co and 137Cs from the soil of a high concentration (2850 Bq/kg) were increased by 13.7% and 3.9% more than those from the soil of a low concentration (135 Bq/kg). The larger the particle size of the soil was, the higher the removal efficiency of 137Cs was. Namely, the removal efficiency of 137Cs from the soil of average 1.2 mm particle size was increased by about 2% more than that from the soil of average 0.6 mm particle size. Also, the removal efficiencies of 60Co and 137Cs by the application of an electric current of 20 mA/cm2 were increased by 1.3% and 4.2% more than those by the application of 10 mA/cm2. The removal efficiencies of 60Co and 137Cs from the radioactive soil of 1825 Bq/kg were 99.9% and 94.3% by an electrokinetic-flushing decontamination by the application of an electric current of 20 mA/cm2 for 50 days.