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在研究堆中的辐照条件下，U3Si2-Al 弥散型燃料的燃料颗粒和基体界面发生相互扩散。由于相互扩散反应,在每个 U3Si2颗粒的周围形成 U3Al7Si2反应层。反应层厚度随辐照时间和裂变密度而增加。反应层的形成造成了 U3Si2燃料和铝基体的消耗。该过程导致燃料芯体几何结构的演化。根据弥散体中燃料的随机分布特点,作者采用蒙特卡罗方法发展了燃料芯体结构演化的模拟方法。每个颗粒的特性都可以用直径和位置来表示。芯体结构参数包括颗粒尺寸分布、制造状态下的燃料体积分数、反应层厚度、反应层体积、U3Si2燃料体积分数、铝体积分数、接触几率和颗粒相互连接分数。特别是对于制造状态下的燃料体积分数为 43%时,颗粒尺寸较好地服从正态分布。模拟了在 6 mm×6 mm×0.5 mm 的芯体体积中 13 000 个抽样颗粒的情况下,各芯体结构参数随反应层厚度从 0～16 μm 变化时的函数变化情况。
Under the irradiation conditions in the research reactor, interfacial diffusion occurs between the fuel particles and the matrix interface of the U3Si2-Al dispersed fuel. Due to the interdiffusion reaction, a U3Al7Si2 reaction layer is formed around each U3Si2 particle. The thickness of the reaction layer increases with the irradiation time and the fission density. The formation of the reaction layer causes the consumption of U3Si2 fuel and the aluminum matrix. This process leads to the evolution of the fuel core geometry. Based on the random distribution of fuel in the dispersion, the authors developed a simulation method for the evolution of the fuel core structure using Monte Carlo method. The characteristics of each particle can be expressed in terms of diameter and position. Core structure parameters include particle size distribution, fuel volume fraction during fabrication, reaction layer thickness, reaction layer volume, U3Si2 fuel volume fraction, aluminum volume fraction, contact probability, and particle interconnection fraction. Especially for the 43% volume fraction of fuel in the as-manufactured state, the particle size better follows the normal distribution. The variation of the structural parameters of each core with the thickness of the reaction layer varying from 0 to 16 μm was simulated with 13 000 sampling particles in a 6 mm × 6 mm × 0.5 mm core volume.