Understanding xenon and vacancy behavior in UO₂, UN and U₃Si₂: a comparative DFT+Ustudy

Abstract

Extensive attention has been paid to accident tolerant fuels (ATFs), such as uranium mononitride (UN) and uranium sesquisilicide (U3Si2), which are regarded as the potential candidates to replace uranium dioxide...

Effect of fission defects on tensile strength of U3Si2 Σ5(210) grain boundary from first-principles calculations

“…From our predicted results 52 and previous data, 43 the most energetically favorable occupation of Xe atoms in bulk U 3 Si 2 is on the substitution site rather than the interstitial site. In Fig.…”

“…This is because the size of the V U defect is larger than that of V Si , resulting in a relatively loose atomic arrangement with the weak interatomic bonding on the GB of U 3 Si 2 . 52 This confirms that V U is more likely to segregate to the U 3 Si 2 S5(210) GB, which may be attributed to the stability and lattice disturbance related to the neighbouring structural and chemical environment of defects. In Fig.…”

“…The conclusion of vacancy (or Xe) defects within the U 3 Si 2 grain interior is in consistent with that in bulk supercell. 43,52 Thus, the concurrent segregation of defects can be simply regarded as the aggregation of two individual defect species according to the low equilibrium defect concentration. 43…”

Phase-field simulation on fission gas release behavior of large grain UO₂ fuel

“…, 分别为空位与裂变气体原子缺陷的 形 成 能 , 取 = 5.1 eV [19] , Xe原 子 在 空 位 中 的 溶解能 = 5.21 eV [20] , 取裂变气体原子的形成能 为空位形成能与原子在空位中的溶解能之和, = = 10.31 eV; k B 为玻尔兹曼常量, T为 温度. 对于气泡相, 取气体平衡浓度 = 0.454 [9] , 持气泡相中c v + c g ≤ 1, 取空位平衡浓度 = 0.9 -c g , 随着c g 的增大, 将逐渐减小.…”