Cold Crucible Induction Melting for Production of Murataite Matrices for Immobilization of Actinides

Abstract

Crystalline phases are promising materials (matrices) for isolating nuclear waste with long-lived radionuclides, actinides first of all. Melting in an induction-heated cold crucible was used to produce a potential matrix with the following nominal composition: 50 wt % TiO₂, 10 wt % MnO, 10 wt % CaO, 5 wt % Al₂O₃, 5 wt % Fe₂O₃, 10 wt % ZrO₂, and 10 wt % CeO₂ (actinide simulator). The target murataite phase is the predominant phase in the sample; crichtonite and glass are present as well. The emergence of glass is due to contamination of the melt by the refractory coating of the crucible. As in other samples produced by melting, murataite is represented by zonal crystals, the center of which is enriched in heavy elements (Zr and Ce). Murataite accounts for up to 80% of simulated radioactive waste. Irradiation with a dose of 22 million Gray resulted in partial amorphization of crichtonite. According to the results of a dynamic test (single pass flow test, SPFT), the rate of Ce leaching (powder, water, 70°C) is 10^–4–10^–5 g/(m² day).