A Demonstration Test to Separate Minor Actinides in High-Level Liquid Waste by N,N,N',N',N'',N''-Hexaoctyl Nitrilotriacetamide (HONTA) Using Mixer-Settler Extractors in a Hot Cell

A demonstration test was performed to separate minor actinides (MA; Am and Cm) by N,N,N',N',N'',N''-hexaoctyl nitrilotriacetamide (HONTA) as an extractant using mixer-settler extractors installed in a hot cell. A high-level liquid waste containing MA, and rare earths (RE; Y, La, Nd, and Eu) was used as the feed. HONTA diluted to 0.05 mol/dm³ in n-dodecane was fed as the organic phase, and a part of the organic phase was reused without solvent regeneration. HONTA effectively extracted MA, whereas RE were less extractable. Consequently, the Y, La, Nd, and Eu ratios distributed to a RE fraction were >99.9%, 99.2%, 61.8%, and 81.4%, respectively. The Am and Cm ratios distributed to an MA fraction were 86.8% and 74.7%, respectively, and a substantial amount of MA (0.12 g) was recovered in the MA fraction by the end of the cumulative duration of 40 h.