Uranium-silicide (U-Si) fuels are being pursued as a possible accident tolerant fuel (ATF). This uranium alloy benefits from higher thermal conductivity and higher fissile density compared to uranium dioxide (UO₂). In order to perform engineering scale nuclear fuel performance simulations, the material properties of the fuel must be known. Currently, the experimental data available for U-Si fuels is rather limited. Thus, multi-scale modeling efforts are underway to address this gap in knowledge. Interfaces play a critical role in the microstructural evolution of nuclear fuel under irradiation, acting both as sinks for point defects and as preferential nucleation sites for fission gas bubbles. In this study, a semi-empirical modified Embedded-Atom Method (MEAM) potential is utilized to investigate grain boundaries and free surfaces in U₃Si₂. The interfacial energy as a function of temperature is investigated for ten symmetric tilt grain boundaries, eight unique free surfaces and voids of radius up to 35 Å. The point defect segregation energy for both U and Si interstitials and vacancies is also determined for two grain boundary orientations. Finally, the entropy change and free energy change for grain boundaries is calculated as a function of temperature. This is the first study into grain boundary properties of U-Si nuclear fuel.

硅化铀（U-Si）燃料正在寻求作为可能的事故耐受燃料（ATF）。与二氧化铀（UO ₂）。为了进行工程规模的核燃料性能模拟，必须知道燃料的材料特性。当前，可用于U-Si燃料的实验数据相当有限。因此，正在进行多尺度建模工作以解决这一知识差距。界面在辐射下核燃料的微结构演变中起着至关重要的作用，既充当点缺陷的沉陷，又充当裂变气泡的优先成核位点。在这项研究中，利用半经验改进的嵌入原子方法（MEAM）势来研究U ₃ Si _2中的晶界和自由表面。对于十个对称的倾斜晶界，八个独特的自由表面和半径最大为35的空隙，研究了界面能随温度的变化。还针对两个晶界取向确定了U和Si间隙和空位的点缺陷偏析能。最后，计算出晶界的熵变和自由能随温度的变化。这是对U-Si核燃料晶界特性的首次研究。