Rapid immobilization of simulated radioactive soil waste by microwave sintering

A rapid and efficient method is particularly necessary in the timely disposal of seriously radioactive contaminated soil. In this paper, a series of simulated radioactive soil waste containing different contents of neodymium oxide (3-25 wt.%) has been successfully vitrified by microwave sintering at 1300 °C for 30 min. The microstructures, morphology, element distribution, density and chemical durability of as obtained vitrified forms have been analyzed. The results show that the amorphous structure, homogeneous element distribution, and regular density improvement are well kept, except slight cracks emerge on the magnified surface for the 25 wt.% Nd2O3-containing sample. Moreover, all the vitrified forms exhibit excellent chemical durability, and the leaching rates of Nd are kept as ∼10−4-10−6 g/(m2 day) within 42 days. This demonstrates a potential application of microwave sintering in radioactive contaminated soil disposal.