[en] For volume reduction of the wastewater generated on washing the soil contaminated with cobalt, recycling and reuse experiments of the wastewater were executed. Also, the soil remediation efficiency by repetitive washing with fresh citric acid was analyzed. The soil around TRIGA was sampled for the experiment. Results of recycling experiment by replacement-precipitation method were as follows. The remediation efficiency of 1st recycling wastewater was 97% and that of 2nd recycling wastewater was 94%. Aslo, To obtain remediation efficiency over than 90%, the 5th repetitive washing with fresh citric acid was needed

[en] The two research reactors (TRIGA MARK II and III) in Korea are to be decommissioned in the near future. When the reactors are completely dismantled, the site may remain contaminated due to the long period of operation. We assume that the site is radioactively contaminated by Co-60. Soils gathered from the research reactor site were artificially contaminated with Co²⁺ ion. The desorption characteristics of Co²⁺ ion from the soil surface by citric acid solution were investigated. Decontamination performances of citric acid and EDTA on soil stored in the radioactive waste drums was examined. The feasibility test of recycling the citric acid was also performed. We concluded that the radioactive waste volume could be reduced significantly by soil washing with a citric acid solution