Calculation and Analysis of Multiscale Coupling of Dispersion Plate-type Fuel
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摘要: 弥散型板状燃料两相弥散材料的多尺度特点对其性能研究提出了挑战。为准确分析与评价U3Si2/Al弥散型板状燃料在堆内的性能,在已有的U3Si2/Al弥散型芯体的等效物性、行为模型基础上,针对等效芯体较为复杂的蠕变特性,建立其蠕变衰减系数模型以准确模拟两相复合材料的蠕变行为。同时,构建了三维燃料板模型、一维颗粒球模型,并提出了将三维燃料板模型与一维颗粒球模型耦合的跨尺度耦合方法,以在宏观分析的同时,获取燃料芯体各部位微观颗粒行为。基于跨尺度多物理场耦合分析工具,开展针对弥散型燃料的多物理场分析,并对燃料颗粒的尺寸与体积份额的影响进行了评估。结果显示,增加颗粒的尺寸和体积份额只略微提高燃料中心温度,影响可忽略;当体积份额从30%提升到40%时,燃料颗粒应力增加11.6%。Abstract: The multi-scale characteristics of two-phase dispersion materials in dispersion-type plate fuel pose challenges to its performance research. To accurately analyze and evaluate the in-pile performance of U3Si2/Al dispersion-type plate fuel, based on the existing equivalent physical properties and behavior model of U3Si2/Al dispersion fuel meat, the creep attenuation coefficient model was established to accurately simulate the creep behavior of two-phase composites, particularly focusing on the complex creep characteristics of the equivalent fuel meat. Additionally, a three-dimensional macroscopic fuel plate model and a one-dimensional sphere model were constructed, and a multi-scale coupling method was proposed to couple these models, enabling simultaneous simulation at both scales. Based on the multi-scale multi-physics coupling analysis tool, the multi-physical field analysis of U3Si2/Al dispersion-type fuel was conducted, and the impact of fuel particle size and volume fraction was evaluated. The results inidcate that increasing the particle size and volume fraction only slightly increases the central temperature of the fuel; however, when the volume fraction increases from 30% to 40%, the fuel particle stress increases by 11.6%.
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表 1 跨尺度耦合方法综合验证算例输入参数
Table 1. Input Parameters for Verification Cases of Multi-Scale Coupling Method
参数名 参数值 体积份额/% 40 颗粒尺寸/μm 25 压力/MPa 300 温度/K 400 裂变率/ (s−1·cm−3) 1.2×1014 时间/s 1×107 最大燃耗/%FIMA(FIMA表示已裂变
原子数与初始的总装料金属原子数之比)10.0 表 2 跨尺度耦合模拟输入参数
Table 2. Input Parameters for Multi-Scale Coupling Simulation
参数名 参数值 芯体等效体功率/(W·m−3) 3.68636×109×cos[(y/0.77)×3.14)]
(y为Y轴坐标,m)最大快中子注量率/(m−2·s−1) 2.0×1018 最大燃耗/%FIMA 20 冷却剂温度/K 313.15 对流换热系数/(W·m−2·K−1) 25000 冷却剂压力/MPa 0.152 -
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