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Molecular dynamics investigation of grain boundaries and surfaces in U3Si2
Journal of Nuclear Materials ( IF 2.8 ) Pub Date : 2018-12-07 , DOI: 10.1016/j.jnucmat.2018.12.008
Benjamin Beeler , Michael Baskes , David Andersson , Michael WD. Cooper , Yongfeng Zhang

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.



中文翻译:

U 3 Si 2中晶界和表面的分子动力学研究

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。

更新日期:2018-12-07
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