Separation of cesium from intermediate level liquid radioactive waste by solvent extraction with antioxidants

Abstract

The intermediate level liquid radioactive wastes (RAW) isussed from nuclear power plants have high salt contents ca 200 g·dm−3, the pH of liquid RAW being 12.5–13.7. A convenient method for separation of cesium under these conditions is solvent extraction with substituted phenols. For this purpose weere tested antioxidants produced in Czechoslovakia: AO 2246 [2,2-methylene-bis-(4-methyl-6-tertbutyl)phenol]; AO 4 [2-tertbutyl-4-(2-phenylpropyl)phenol]; AO 4K [2,6-ditertbuty-4-methylphenol]; AO 301 [2,2-methylene-bis-(4-{2-phenylpropyl}-6-tert-butyl)phenol]; and one antioxidant imporoted from Japan—NOCRAC 2246. This antioxidant is equivalent to AO 2246. After the first experiment it was found that the extraction efficiency for antioxidants AO 4 and Ao 301 is very low and the following experiments were made with AO 2246 (NOCRAC 2246) and AO 4K. Some effects on extracton as, pH of water phase, influence of diluent, influence of concentration of antioxidants, extraction time, were studied. The best results gave antioxidant NOCRAC 2246 in nitrobenzene, the extraction efficiency was 92.3% with pH 13.23.