Oxidative Alkaline Leaching of Americium from Simulated High‐Level Nuclear Waste Sludges

Abstract Oxidative alkaline leaching has been proposed to pretreat the high‐level nuclear waste sludges to remove some of the problematic (e.g., Cr) and/or nonradioactive (e.g., Na, Al) constituents before vitrification. It is critical to understand the behavior of actinides, americium and plutonium in particular, in oxidative alkaline leaching. We have studied the leaching behavior of americium from four different sludge simulants (BiPO4, BiPO4 modified, Redox, PUREX) using potassium permanganate and potassium persulfate in alkaline solutions. Up to 60% of americium sorbed onto the simulants is leached from the sludges by alkaline persulfate and permanganate. The percentage of americium leached increases with [NaOH] (between 1.0 and 5.0 M). The initial rate of americium leaching by potassium persulfate increases in the order BiPO4 sludge