基于刚柔耦合的改进型控制棒组件变形通道落棒行为分析

燃料组件在堆芯内经历长期辐照后易产生弯曲形变，影响控制棒的安全落棒，因此亟需研究变形通道下控制棒落棒行为影响机制。通过数值模拟手段对导向管发生弯曲变形后的落棒行为规律进行分析研究，利用刚柔耦合方法分别计算直型、C型、S型导向管内的落棒行为，分析整个落棒行程、速度、加速度、沿程碰撞力随时间的变化情况，对比直型和2种不同变形通道对落棒行为的影响。研究结果表明，刚柔耦合方法可以较好地模拟变形通道下的落棒行为，C型落棒未发生卡滞，S型落棒卡滞于第2道弯折处。本研究将有助于为弯曲变形导致落棒卡涩问题的极限弯曲阈值提供判断依据，为工程设计提供参考。 

Analysis on the Improved Control Rod Drop Behavior among Deformation Channels Based on the Rigid-flexible Coupling

The fuel assembly is prone to bend after long-term irradiation in the core, which affects the safe drop of the control rod. Therefore, it is urgent to study the influence mechanism of the control rod drop behavior under the deformation channel. By means of numerical simulation, the law of rod drop behavior after bending deformation of guide tube is analyzed and studied, the rigid-flexible coupling method is used to calculate the rod drop behaviors in the straight, C-shaped and S-shaped guide tubes respectively, analyze the variation of the entire rod drop journey, velocity, acceleration, and collision force along the journey with time, and the effects of straight and two different deformation channels on rod drop behavior are compared. The results show that the rigid flexible coupling method can better simulate the rod drop behavior under the deformation channel. The C-shaped rod drop does not get stuck, and the S-shaped rod drop is stuck at the second bend. This study will help to provide a basis for judging the ultimate bending threshold of the problem of rod drop sticking caused by bending deformation, and provide a reference for engineering design.