U3Si2燃料由于热导率高、铀密度大等特点，是当前耐事故燃料的候选材料之一。裂变气体气泡演化和释放是影响U3Si2燃料堆内性能的重要行为。本文针对反应堆内燃料裂变气体演化开展了相关机理和模型研究。通过对比U3Si2燃料和UO2燃料裂变气体行为差异，考虑晶态及非晶态U3Si2结构特征，分别建立了U3Si2燃料晶内气体原子扩散方程和非晶U3Si2内气体气泡演化方程。结合低尺度模拟方法，研究并确定了U3Si2燃料晶内、晶间和非晶状态气体行为关键参数，分别建立了轻水堆U3Si2燃料裂变气体晶内晶间模型以及可针对研究堆U3Si2弥散燃料相分析的裂变气体非晶模型。

U3Si2 fuel is an attractive candidate material for accident tolerant fuel due to its high thermal conductivity and high uranium density. Its evolution and release behavior of fission gas are significant for its effection on the in-pile performance and studied in this paper. With taking account of structural characteristics of amorphous U3Si2 fuel, fission gas behaviors of U3Si2 fuel and UO2 fuel were compared to establish the atomic diffusion equation of crystal U3Si2 fuel and the bubble evolution equation of amorphous U3Si2 fuel. According to the simulation data by low scale method, key parameters of gas behavior in the intragranular, intergranular and amorphous state of U3Si2 fuel were studied and determined. The fission gas model of crystal U3Si2 fuel in light water reactor and the gas model of U3Si2-Al fuel amorphous phase in research reactor were established respectively in this paper.