Radioactive contamination and electrochemical decontamination of the structural material for the cold crucible inductive melter

Cold crucible inductive melting (CCIM) is a pivotal technology for nuclear waste vitrification, yet the structural materials (e.g., Fe-Cr-Ni alloys) face severe radioactive contamination under high-temperature and corrosive waste streams. This study investigates the contamination mechanisms and electrochemical decontamination strategies for the structural materials for the CCIM. Multiscale characterization techniques revealed that Fe 3 O 4 and Cr 2 O 3 dominate the surface alteration layer (up to 50 μm), with MnO 2 to Mn 2 O 3 phase transitions increasing porosity and accelerating radionuclide penetration. Simulated radionuclides (Cs, Mo, Se) exhibited distinct behaviors: Cs accumulated at 20–50 μm depths due to the volatility from the top surface, while Mo (as MoO 2 ) and elemental Se showed surface depletion via dissolution or evaporation. Electrochemical decontamination experiments demonstrated that low-concentration acid (0.1 mol/L) with graphene and surfactant additives achieved an electric power of 284.2 W, surpassing traditional high-acid methods by 40%. The synergistic effect of graphene (enhancing conductivity) and sulfuric acid enabled the selective dissolution of Fe and Cr-rich oxides. These findings provide a foundation for optimizing scalable, low-waste decontamination protocols in extreme nuclear environments.