At the equilibrium state, there is a balance between concentrations of various point defects. The number of defects may be described by the equations similar to the law of mass action. In this work, we use such approach and molecular dynamics simulations to calculate equilibrium concentrations of defects for different nuclear fuels: UN, UO₂, and UC. We show that some types of phase transitions may be described as the accumulation of point defects. Namely, we consider (1) superionic transition and melting at heating and (2) appearance of pure uranium in uranium-rich composition. We discuss the reasons of narrow homogeneity area for UN, which is observed in the phase diagram. Also, we pay attention to the grounds of strong heat capacity increase occurring for all mentioned fuels at heating.

在平衡状态下，各种点缺陷的浓度之间存在平衡。缺陷的数量可以由类似于质量作用定律的方程式描述。在这项工作中，我们使用这种方法和分子动力学模拟来计算不同核燃料（UN，UO ₂和UC）的缺陷平衡浓度。我们表明，某些类型的相变可能被描述为点缺陷的累积。即，我们考虑（1）富铀组合物中纯铀的超离子转变和加热熔化，以及（2）纯铀的出现。我们讨论了在相图中观察到的联合国同质区域狭窄的原因。同样，我们要注意所有提到的燃料在加热时会发生强烈的热容量增加。