Optimization of heat-liberating batches for ash residue stabilization

The ash residue obtained after incineration of solid radioactive waste is a dusting poly-dispersed powder like material that contains radioactive nuclides (137Cs, 90Sr, 239Pu, hor(ellipsis)). Specific radioactivity of the ash can be about 105--107 Bq/kg. In order to dispose of the ash, residue shall be stabilized by producing a monolith material. The ash residue can be either vitrified or stabilized into a ceramic matrix. For this purpose the ash residue is mixed with fluxing agents followed by melting of obtained composition in the different type melters. As a rule this requires both significant energy consumption and complex melting equipment. A stabilization technology of ash residue was proposed recently by using heat liberating batches-compositions with redox properties. The ash residue is melted due to exothermic chemical reactions in the mixture with heat-liberating batch that occur with considerable release of heat. Stabilization method has three stages: (1) preparation of a mixture of heating batch and ash residue with or without glass forming batch (frit); (2) ignition and combustion of mixed composition; (3) cooling (quenching) of obtained vitreous material. Combustion of mixed composition occurs in the form of propagation of reacting wave. The heat released during exothermic chemical reactions provides melting of ash residue components and production of glass-like phase. The final product consists of a glass like matrix with embedded crystalline inclusions of infusible ash residue components