Waste Package Component Interactions with Savannah River Defense Waste Glass in a Low-Magnesium Salt Brine

Interactive leaching experiments were performed with Savannah River 165 defense waste glass at 90°C in a low-magnesium salt brine (∼100 mg/ℓ) with various amounts of steel present to simulate interactions between the metal container and the glass. Synergistic interactions occurred between the container material and the glass, which increased the glass dissolution rate. Measured quasi-steady-state solution concentrations of ²³⁹Pu, ²³⁷Np, and ²⁴³Am were reasonably consistent with published solubilities for the respective oxides. Decreasing ²³⁸U concentrations were observed with increasing solution pH, inconsistent with the behavior of uranyl carbonates that presumably predominate at the slightly alkaline pH of the tests. Uranium and plutonium formed pseudocolloids with hematite particles that rapidly formed during the tests. Particle size measurements showed the median size to be >5 μm in diameter.