We are interested in developing a fundamental and predictive understanding of actinide chemistry in aqueous solution under conditions relevant to nuclear-waste storage and reprocessing of spent fuel to address aggregate and colloid formation. Intractable, small aggregates in nuclear-waste streams can impair clean-up, forcing a low-level waste stream to be treated as high-level waste, thereby increasing treatment costs. Metal oligomers, aggregates, clusters, nanophases and colloids are ubiquitous in aqueous chemistry. Thought to form via the condensation reactions of hydrolyzed metal ions, intrinsic dissolved aggregates or colloids are generally described as poly-dispersed hydroxides or hydrous oxides with varying stoichiometry and no well-d...