EXTRACTION OF U(VI), TH(IV) AND SOME FISSION-PRODUCTS FROM NITRIC-ACID MEDIUM BY SULFOXIDES AND EFFECT OF GAMMA-IRRADIATION ON THE EXTRACTION

The extracting abilities for thorium, uranium and some fission product s by five sulfoxides are given. The results show that di(2-ethylhexyl) sulfoxide (DEHSO) is not only completely miscible with kerosene, but also superior to tri-n-butyl phosphate in some properties. The extract ion behavior of uranium, thorium and some fission products such as zir conium, niobium and ruthenium from aqueous nitric acid with DEHSO in k erosene has been studied over a wide range of conditions. DEHSO extrac ted uranium and fission products better than TBP under all conditions and is similar to TBP in extraction of thorium. A study of extraction mechanism indicates that U and Th are extracted as disolvates, whereas HNO3 is extracted as monosolvate. Extraction of the two actinides dec reases with increasing temperature, indicating the extraction to be ex othermic. Preliminary studies show that gamma-ray irradiated DEHSO ext racts Zr and Nb to a smaller extent than irradiated TBP in the range o f 10(4)-10(7) rad.