Currently in the world there are power reactors, reactors for plutonium production and research reactors whose number is more than 100 pieces of Graphite in the above mentioned reactors is used as the reflector, moderator, and also as Fuel cladding. Flameless combustion is a promising method of reducing the amount of solid radioactive waste. Method of flameless combustion is based on the oxidation of TRO in the oxide-carbonate melts and significantly reduces the volume of radioactive graphite. Thermodynamic modeling of oxidation of radioactive graphite in molten Na2CO3-K2CO3-Sb2O3 in an atmosphere of carbon dioxide. To conduct thermodynamic analysis was used the program complex TERRA. Thermodynamic modeling was carried out with initial pressure of one atmosphere, at an initial temperature of 273 K and the final temperature 3273 К. The step change in temperature is 100 K. Based on these data, the analysis of the distribution of elements between the condensed and gas phases. The modelling shows that the carbon disappears at a temperature of 873 K. The heating of the system up to 1073 K leads to the evaporation of condensed compounds of antimony. The heating system up to 1673 K leads to the evaporation of condensed compounds of potassium, sodium, chlorine, uranium and cesium. The heating system up to 2273 K, leads to evaporation of condensed compounds of nickel. The heating system up to 2573 K leads to the evaporation of condensed calcium compounds, plutonium, beryllium, strontium, americium and europium. At temperatures above 2573 K, there is only a steam and gas phase.