title: Hexavalent Americium Recovery Using Copper(III) Periodate.
abstract: Separation of americium from the lanthanides is considered one of the most difficult separation steps in closing the nuclear fuel cycle. One approach to this separation could involve oxidizing americium to the hexavalent state to form a linear dioxo cation while the lanthanides remain as trivalent ions. This work considers aqueous soluble Cu3+periodate as an oxidant under molar nitric acid conditions to separate hexavalent Am with diamyl amylphosphonate (DAAP) in n-dodecane. Initial studies assessed the kinetics of Cu3+periodate autoreduction in acidic media to aid in development of the solvent extraction system. Following characterization of the Cu3+periodate oxidant, solvent extraction studies optimized the recovery of Am from varied nitric acid media and in the presence of other fission product, or fission product surrogate, species. Short aqueous/organic contact times encouraged successful recovery of Am (distribution values as high as 2) from nitric acid media in the absence of redox active fission products. In the presence of a post-plutonium uranium redox extraction (post-PUREX) simulant aqueous feed, precipitation of tetravalent species (Ce, Ru, Zr) occurred and the distribution values of241Am were suppressed, suggesting some oxidizing capacity of the Cu3+periodate is significantly consumed by other redox active metals in the simulant. The manuscript demonstrates Cu3+periodate as a potentially viable oxidant for Am oxidation and recovery and notes the consumption of oxidizing capacity observed in the presence of the post-PUREX simulant feed will need to be addressed for any approach seeking to oxidize Am for separations relevant to the nuclear fuel cycle.
authors: Colorado School of Mines , 1500 Illinois Street, Golden, Colorado 80401, United States.
authors: Kevin
authors: K
authors: McCann
authors: Oak Ridge National Laboratory , 1 Bethel Valley Road, Oak Ridge, Tennessee 37830, United States.
authors: Derek M
authors: DM
authors: Brigham
authors: Pacific Northwest National Laboratory , 902 Battelle Blvd., Richland, Washington 99352, United States.
authors: Samuel
authors: S
authors: Morrison
authors: Colorado School of Mines , 1500 Illinois Street, Golden, Colorado 80401, United States.
authors: Jenifer C
authors: JC
authors: Braley