Advances in immobilization of radionuclide wastes by alkali activated cement and related materials

Nuclear power is seen a significant part of new energy industry because of the low carbon emission feature and high efficiency. Safe and reliable immobilization of radionuclide wastes from nuclear power station is important for its operation. When the Portland cement-based solidifying materials encounter unsatisfying acid resistance, alkali activated cements (AACs) emerge as more durable, low-cost and environmentally friendly options. This paper provides an overview of recent advances of research on immobilization of radionuclide wastes by AAC and related materials. It discusses mechanisms and efficiency of different AACs on the immobilization of low- and intermedium-level radionuclide wastes, representatively the simulating radionuclides strontium and cesium. Immobilization of other radionuclides, such as 60Co, 113Cd and 129I, by AACs is also reviewed. It is agreed that the immobilization efficiency of radioactive nuclides in AACs is generally better than that in Portland cement-based materials. Technical challenges and future research and development are proposed. [Display omitted] •Alkali-activation technology has the great potential in immobilizing radioactive wastes.•Immobilization via ion exchange, physical adsorption, and encapsulation by gel matrix.•AAC immobilization generally has better efficiency than Portland cement.•Low-Ca AAC has unique microstructure due to high crosslink molecular structure.•AACs are good precursors for ceramic sintering to immobilize nuclide ions.