Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), Dalian University of Technology, Dalian, Liaoning, China.
Science and Technology on Reactor System Design Technology Laboratory, Nuclear Power Institute of China, Chengdu, Sichuan, China.
Phys Chem Chem Phys. 2023 May 31;25(21):14928-14941. doi: 10.1039/d3cp01199b.
Extensive attention has been paid to accident tolerant fuels (ATFs), such as uranium mononitride (UN) and uranium sesquisilicide (USi), which are regarded as potential candidates to replace uranium dioxide (UO) in light-water reactors (LWRs). However, the thermodynamic behavior of fission gas atoms in these fuels that can quantitatively affect the burnup characteristics of ATFs needs to be explored. To this end, systematic density functional calculations on the energetic properties of xenon (Xe)-vacancy complexes in UO, UN and USi are performed with the GGA+ approach as well as the corrected chemical potential. The stabilities of Xe-vacancy clusters, including interstitial trap site (IS), mono-, bi- and tri-atomic vacancies, are thoroughly assessed. The formation energies of vacancy complexes indicate that they are more likely to form vacancy cluster defects and their complexes with Xe in UO and to generate mono-atomic vacancy and Xe-vacancy complexes in both UN and USi. Xe can be strictly confined by the trap sites in UO and UN, and yet in USi, it prefers to move to the centre of a large free volume trap site. The strong solubility of Xe in USi indicates the excellent storage capacity of fission gas products in the matrix. Overall, this work provides comprehensive insights into the origins of the interplay between Xe and vacancies as well as the thermodynamic behavior of defects in uranium-based fuels.
人们对事故容错燃料（ATF）给予了广泛关注，例如氮化铀（UN）和硅化铀（USi），它们被认为是替代轻水堆（LWR）中二氧化铀（UO）的潜在候选燃料。然而，裂变气体原子在这些燃料中的热力学行为需要加以研究，因为这些行为会定量影响 ATF 的燃耗特性。为此，采用 GGA+方法和修正的化学势，对 UO、UN 和 USi 中氙（Xe）-空位复合物的能量特性进行了系统的密度泛函计算。彻底评估了 Xe-空位团簇的稳定性，包括间隙陷阱位（IS）、单空位、双空位和三空位。空位复合物的形成能表明，它们更容易在 UO 和 UN 中形成空位团簇缺陷及其与 Xe 的复合物，并在 UN 和 USi 中生成单空位和 Xe-空位复合物。Xe 可以被 UO 和 UN 中的陷阱位严格限制，但在 USi 中，它更倾向于移动到大自由体积陷阱位的中心。Xe 在 USi 中的高溶解度表明裂变气体产物在基体中有良好的存储能力。总的来说，这项工作全面深入地了解了 Xe 与空位之间的相互作用的起源以及铀基燃料中缺陷的热力学行为。
