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

Abstract

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 95 Zr and 95 Nb (up to 90%) as well as 131 I, partially 103 Ru (∼ 30%), 99 Tc (20%) and lanthanides (up to 10%) also passed into the adduct phase. In this case complete separation of U from 137 Cs, 85 Sr, 140 Ba as well as from the bulk of 140 La, 141-144 Ce and 147 Nd 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.