Advance of pretreatment method using supercritical fluid extraction

Nagaoka, Mika  ; Fujita, Hiroki

The radioactivities in the environmental samples are analyzed to monitor the nuclear power facilities. The pretreatment of radioactive nuclides of alpha and beta emitters in the environmental samples is performed with acid to decompose organic matter and extract object nuclide such as Sr-90, U and Pu. However, the pretreatment using acid has many problems of acid effluent and gas, corrosion of facilities and so on. Therefore, we develop to the new pretreatment method using supercritical water instead of acid. At first, we investigate the extraction yield of stable Sr and U-238 in solvent in the SCWO reaction on various situations. The yield of stable Sr was at most about 60%, while U-238 was less than 1% in this study. In the future, we try to apply a catalyst in the SCWO to increase the yield of extraction.