The mechanism of noncongruence of melting and determination of composition of the uranium dioxide melt on the basis of its defect structure

The amount of oxygen taken or given up that is necessary to rupture for each kind of defects, when the $\mathrm{UO}_{2-x}$ crystalline lattice is in the state of complete possible filling (on the solidus line), is determined by consideration of the conditions for such destruction at $T=const$. This allows for determining the stoichiometry and composition of the formed melt (on the liquidus line). Thereby, the physical mechanism of the non-congruence of melting the compound substances is determined and the composition of the melt of uranium dioxide is found in the whole region of its existence.