Graphite is used as moderator and reflector of neutrons. In addition, in the construction of reactors, graphite is used as seals and bearings. The mass of graphite in the reactors is 1-2 tons At decommissioning graphite reactors produce large quantities of radioactive graphite waste. Existing methods of treatment of radioactive graphite based on its isolation from the environment. These techniques do not significantly reduce the volume of radioactive graphite waste. Resulting in the reprocessing of irradiated reactor graphite by oxidation of the molten salts can be considered as an alternative method of disposal that reduce the volume of radioactive graphite waste. Thermodynamic modeling of oxidation of radioactive graphite in molten Na2CO3-K2CO3-Sb2O3 in an argon atmosphere. To conduct thermodynamic analysis was used the program complex TERRA. Based on these data, the analysis of the distribution of elements between the condensed and gas phases. The result is that the heating system up to 1073 K leads to the evaporation of condensed compounds of antimony and cesium. The heating system up to 1273 K leads to the evaporation of condensed compounds of potassium, sodium, chlorine. The heating system up to 1373 K leads to the evaporation of condensed compounds of Nickel. The heating system up to 1673 K leads to the evaporation of condensed compounds of uranium, calcium and strontium. The heating system up to 1773 K leads to the evaporation of condensed compounds of plutonium, beryllium, americium and europium. At temperatures above 1773 K, there is only a steam and gas phase.