Geoconcrete monolith as stable matrix material for immobilization of radioactive wastes

Immobilization of the intermediate-level radioactive waste (RAW) in a new type of binding agents, geoconcrete monoliths, was studied. The experiments were performed using liquid radioactive wastes of various salinities formed in the course of operation of nuclear power plants and various sorbents saturated with radionuclides, in particular, with ¹³⁷Cs. The prolonged operation life of geoconcretes is determined by the chemical and mineralogical composition of the hydrated neogenic compounds, which are analogs of water-resistant rock-forming silicate materials. A procedure for synthesis of a geoconcrete matrix with immobilization of biologically important radionuclides was developed, and the properties of geoconcrete monolith (GCM) were studied. The pilot experiments with real RAW were performed. The strength of the GCM samples exceeds by a factor of 2–4 the level prescribed by the regulations, and the leaching rate of ¹³⁷Cs is lower than the prescribed level by 2–3 orders of magnitude.