Application of a wet oxidation method for the quantification of ³H and ¹⁴C in low-level radwastes

Wet oxidation methods are utilized to separate and quantify (3)H and (14)C radionuclides in inorganic and organic radwastes generated at nuclear facilities. Because (3)H and (14)C are pure beta emitters with half-lives of 12.3 and 5,730 years, respectively, these radionuclides should be chemically separated from other radionuclides present in radwastes for accurate quantification. In particular, a collection technique for (14)C radionuclide in radwastes is needed because it is converted into (14)CO2 gas by an oxidation reaction. To confirm the recoveries of (3)H and (14)C, various standard radioactive sources were used to verify the proposed method. Because the majority of (3)H radionuclides are distributed in tritiated water (HTO), only tritiated water was used as a standard for (3)H radionuclides. Additionally, (14)C-labeled methanol ((14)CH3OH), lauric acid ((14)CH3(CH2)10COOH), sodium bicarbonate (NaH(14)CO3), and toluene (C6H5(14)CH3) were used as (14)C standards. The compounds were oxidized with chemical oxidants and then separated. The individual species were mixed with a scintillation cocktail and counted using a liquid scintillation counter. The recoveries of (14)C and (3)H were 82-97% and 98%, respectively. The wet oxidation method will be applied to RI wastes for clearance.