Recovery of U and Pu from simulated spent nuclear fuel by adducts of organic reagents with HNO3 followed by their separation from fission products by countercurrent chromatography

The primary patterns of isolation of actinides from their dioxides with supercritical carbon dioxide containing adducts of tri-n-butyl phosphate and other organic reagents with nitric acid has been investigated. The effective extraction of actinides from their dioxides was achieved using these adducts under common (ambient) conditions without supercritical carbon dioxide, which makes the performance of the process significantly easier. Extraction of uranium and the primary fission products from a simulated spent nuclear fuel has been studied. It was shown that at almost quantitative extraction of U (>99%), most 95Zr and 95Nb (up to 90%) as well as 131I, partially 103Ru (∼30%), 99Tc (20%) and lanthanides (up to 10%) also passed into the adduct phase. In this case complete separation of U from 137Cs, 85Sr, 140Ba as well as from the bulk of 140La, 141–144Ce and 147Nd was observed. After dissolution of the adduct containing U and partially fission products in liquid carbon dioxide the extract was transported into a separation column of a planetary centrifuge, and separation of U from remaining fission products was performed by countercurrent chromatography in the dynamic mode.