Actinide Species in Alkaline Media

Using a variety of different techniques, this program attempts to provide relevant fundamental data that will reduce the number of surprises (related to actinide behavior) that occur during sludge washing and tank waste processing. This work builds upon the results of earlier fundamental studies of actinide chemistry in concentrated alkali (many conducted in Russia), on the analysis of tank wastes, and on earlier sludge-specific leaching experiments to gain an improved understanding of the relationship between sludge characteristics and actinide dissolution during proposed sludge washing procedures. A successful outcome for this research will be the generation of sufficient supporting information (both fundamental and empirical) that will enable more accurate prediction of the probability of actinide dissolution during the scrubbing of sludges from PUREX, REDOX, and BiPO4 processes. We are studying the mobilization of tri-, tetra-, penta-, and hexavalent actinide cations from sludge simulants; trying to identify mineral phases that might control actinide solubility in sludge simulants; learning about associations between actinide cations and non-radioactive sludge components; investigating the solution-phase chemistry of actinide cations in concentrated alkali; and evaluating the contribution of colloid transport to actinide mobility in sludge washes