Hu Jutao, Li Menglu, Gong Hengfeng, Ren Qisen, Liao Yehong, Xiao Haiyan, Zu Xiaotao
School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, People's Republic of China.
Department of ATF R & D, China Nuclear Power Technology Research Institute Co., Ltd, Shenzhen 518000, People's Republic of China.
J Phys Condens Matter. 2022 Feb 23;34(16). doi: 10.1088/1361-648X/ac519a.
In the past several decades, the USihas received much attention for the development of accident tolerant fuel in light water reactors because of its superior thermal conductivity and higher uranium density. In this study, density functional theory calculations have been carried out to study the occupation and diffusion behaviors of fission products Xe and Cs in USi. It is revealed that the occupation sites of Xe and Cs depend on the chemical environment, and both of Xe and Cs are favorable to substitute for U or Si sites. The diffusions of Xe and Cs in USiare predicted to be via the vacancy mechanism and both of Xe and Cs form cluster easily. As compared with Cs, the Xe exhibits a smaller solubility, faster diffusion as well as stronger clustering tendency, which may cause larger bubble size for Xe than Cs under the same conditions in USi. The differences in the diffusion behaviors between Xe and Cs mainly result from their different valence electronic configurations and different atomic radii.
在过去几十年里，由于其卓越的热导率和更高的铀密度，硅化铀在轻水反应堆中用于开发事故容错燃料受到了广泛关注。在本研究中，进行了密度泛函理论计算，以研究裂变产物氙和铯在硅化铀中的占据和扩散行为。结果表明，氙和铯的占据位点取决于化学环境，并且氙和铯都倾向于替代铀或硅位点。预测氙和铯在硅化铀中的扩散是通过空位机制，并且氙和铯都容易形成团簇。与铯相比，氙表现出较小的溶解度、更快的扩散以及更强的团簇倾向，这可能导致在相同条件下硅化铀中氙形成的气泡尺寸比铯的更大。氙和铯扩散行为的差异主要源于它们不同的价电子构型和不同的原子半径。
