2026年“核理安邦”联合博士生学术论坛

快堆绕丝定位燃料组件辐照变形分析技术及行为研究

Not scheduled

1h

地址：清华大学校内

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Speaker

浩煜 王

摘要

快堆是我国核能“热堆-快堆-聚变堆”三步走发展战略的重要组成部分，燃料组件作为其核心技术之一，其辐照变形行为直接影响堆芯安全运行。快堆采用绕丝定位的三角形紧密栅格燃料组件，辐照后产生的燃料棒直径增大、椭圆化及冷却剂通道变形等问题可能引发局部传热恶化和结构完整性风险。本研究围绕绕丝定位燃料组件辐照变形分析技术开展两方面工作：在精细模拟方面，首次建立了耦合辐照效应、精细结构及预紧力的全生命周期分析方法，完整模拟了从预张紧制造到堆芯运行的变形及应力演化过程。结果表明，运行前期燃料棒全长呈螺旋形变形且包壳周向应力呈“葫芦形”分布，随着辐照进行，活性区外螺旋变形逐渐消退、应力趋于均匀，该演化规律与辐照后热室检查结果吻合。在燃料组件高效计算方面，开发了基于壳-梁单元的三维辐照变形高效分析模型，通过耦合约束、轴向连接单元和一般接触技术简化复杂机械相互作用，并采用用户子程序引入材料辐照行为及非均匀堆内条件。验证表明，该模型在节点数增加6倍的条件下可达到与精细模型相当的精度，求解速度提升10倍以上，兼具高保真度与高效性。后续将进一步深化燃料组件辐照变形机制研究。

Abstract

Fast reactors are an important part of China's three-step nuclear energy development strategy of "thermal reactor - fast reactor - fusion reactor". As one of the core technologies, the irradiation deformation behavior of fuel assemblies directly affects the safe operation of the reactor core. Fast reactors use wire-wrapped triangular tight lattice fuel assemblies. Problems such as increased fuel rod diameter, elliptical deformation, and coolant channel deformation after irradiation may cause local heat transfer deterioration and structural integrity risks. This study focuses on the irradiation deformation analysis technology of wire-wrapped fuel assemblies and conducts two aspects of work: in the aspect of fine simulation, a full life cycle analysis method coupling irradiation effects, fine structures, and pre-tightening forces is established for the first time, which fully simulates the deformation and stress evolution process from pre-tightening manufacturing to reactor core operation. The results show that in the early stage of operation, the fuel rods deform in a helical shape throughout their length and the circumferential stress of the cladding shows a "gourd-shaped" distribution. As irradiation proceeds, the helical deformation outside the active zone gradually disappears and the stress tends to be uniform. This evolution law is consistent with the results of post-irradiation hot cell inspection. In the aspect of efficient calculation of fuel assemblies, a three-dimensional irradiation deformation efficient analysis model based on shell-beam elements is developed. By coupling constraints, axial connection elements, and general contact technology, complex mechanical interactions are simplified, and user subroutines are used to introduce material irradiation behavior and non-uniform in-core conditions. Verification shows that this model can achieve the same accuracy as the fine model with a sixfold increase in the number of nodes and a tenfold increase in the solution speed, combining high fidelity and efficiency. Further research will be conducted to deepen the study of the irradiation deformation mechanism of fuel assemblies.