EXTRACTION OF U(VI), TH(IV) AND SOME FISSION-PRODUCTS FROM NITRIC-ACID BY N,N-DISUBSTITUTED AMIDES AND EFFECT OF GAMMA-RAY IRRADIATION ON THE EXTRACTION

In this work, ten disubstituted amides have been synthesized and the e xtracting ability for U and Th fission products (mainly Zr, Nb and Ru) and the tendency of third phase formation have been studied. From the preliminary studies, two disubstituted amides, N-octylcaprolactam (OC LA) and N-(2-ethyl) hexylcaprolactam (EHCLA) were chosen for further s tudies. All studies were compared with those obtained by using TBP und er exactly the same conditions. The dependence of aqueous nitric acid concentration, extractant concentration, temperature, gamma-ray irradi ation on extraction of Th. U and some fission products were studied. B ack extraction of Th and U from organic phases and third phase formati on were also studied. The studies of the reaction mechanism indicate t hat Th and U am extracted as disolvates, whereas HNO3 is extracted as monosolvate. Extraction distribution of Th and U decrease with increas e of temperature, indicating the extraction reaction to be exothermic. Preliminary studies show that OCLA and EHCLA have better gamma-irradi ation stabilities compared with TBP.