Inorganic Waste Forms for Efficient Immobilization of Radionuclides

The immobilization of long-lived radionuclide wastes generated from nuclear power plants (NPPs) during NPP operation, fuel reprocessing, and decommissioning of nuclear reactors is of great environmental concern. Designing suitable matrices with high durability, stability, and resistivity to various physical and chemical conditions (temperature, pressure, radiation, acidity/alkalinity, etc.) are required for the safe disposal and effective immobilization of radioactive wastes. In this review, we highlight and discuss the key developments in the design and applications of major inorganic waste forms for radioactive waste immobilization. Specifically, we review (i) glasses (borosilicates, phosphates, and sintered glasses), (ii) cements (Portland cement, cast stone/saltstone, hydroceramics, and geopolymer), (iii) synrocs (hollandite, zirconolite, and perovskite), and (iv) ceramics (titanates, sodalite, apatite, monazites, and goethite/magnetite). Additionally, we present future challenges that should be addressed during the design and selection of suitable waste forms for the immobilization of radionuclides. We believe that this paper can deepen our understanding of various waste forms and their roles in radioactive waste immobilization.