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摘要
压水堆燃料组件在服役过程中受冷却剂流致振动影响，会导致燃料棒包壳与定位格架之间发生微幅往复的相对滑移，即格架-燃料棒微动（Grid-to-Rod Fretting, GTRF）。长期的微动累积会引发包壳表面磨损及疲劳损伤，进而导致燃料棒破损失效，成为当前核电机组燃料棒失效的主要原因。因此，研究包壳的微动磨损演化机制和进行磨损预测，对提升燃料组件可靠性及保障反应堆安全运行具有重要意义。本文基于燃料棒包壳与定位格架的实际几何特征，建立了包壳-刚凸接触的微动磨损有限元分析模型，结合Archard磨损理论，利用ABAQUS中的UMESHMOTION子程序与ALE自适应网格技术，实现了微动磨损过程的动态模拟。重点研究了法向载荷和切向位移等微动参数对包壳磨损特性的影响，并深入分析了微动磨损过程中的接触压力和应力分布规律，得到磨损形貌和磨损量曲线，为GTRF磨损行为的预测与评估提供了有效的数值计算方法。
Abstract
Pressurized water reactor (PWR) fuel assemblies are subjected to coolant flow-induced vibration (FIV), which causes small-amplitude reciprocating relative sliding between the fuel rod cladding and the spacer grids, known as Grid-to-Rod Fretting (GTRF). Long-term fretting accumulation induces surface wear and fatigue damage on the cladding, eventually leading to the rupture and failure of the fuel rods. As GTRF is currently one of the primary causes of fuel rod failure in nuclear power plants, investigating the fretting wear evolution mechanism of the cladding and predicting the wear volume is of great significance for improving the reliability of fuel assemblies and ensuring the safe operation of reactors. Based on the actual geometric characteristics of the fuel rod cladding and spacer grids, a finite element analysis (FEA) model for the cladding-to-rigid dimple contact was established in this paper. Incorporating the Archard wear equation, the dynamic simulation of the fretting wear process was achieved by utilizing the UMESHMOTION subroutine and the Arbitrary Lagrangian-Eulerian (ALE) adaptive meshing technique in ABAQUS. The effects of fretting parameters, such as normal load and tangential displacement, on the wear characteristics of the cladding were systematically investigated. Furthermore, the contact pressure and stress distribution patterns during the fretting wear process were analyzed to obtain the wear profiles and wear volume curves. This study provides an effective numerical calculation method for the prediction and evaluation of GTRF wear behavior.
| 关键词 | 微动磨损；燃料组件；有限元分析 |
|---|---|
| Keywords | Fretting wear；Fuel assembly；Finite element analysis |
