基于水力学力的定位格架防勾挂设计研究

定位格架是组成燃料组件的重要部件之一，与上、下管座共同构成了整个组件的外部轮廓。为减小燃料组件吊装过程中的勾挂风险，外条带上设置导向翼已成为定位格架结构设计上的重大改进。本文主要从燃料组件在堆芯的水力学环境出发，基于定位格架在堆芯运行过程中长期承受横向水力载荷可能造成外条带变形的考虑，采用计算流体动力学（CFD）方法，研究了定位格架外条带所承受的水力作用力，并为缓解外条带的受力情况进行了研究和方案设计。研究结果表明，在外条带上开孔能有效减小两侧压差，开孔的位置向下游方向移动效果更明显，同时开孔尺寸增大也能进一步减小两侧压差；更进一步地，将开孔位置移动到刚凸处，其平衡外条带两侧压力的作用更显著，外条带刚凸的开孔设计能更大程度地缓解外条带的水力作用。这些措施将对减小由于水力学力导致的外条带变形起到积极作用，从而在换料时有望降低燃料组件吊装过程中的勾挂风险。 

Design and Research on Anti-Hang-up of Grid Based on Hydraulic Force

Grid is an important part of fuel assembly, making up of the contour of fuel assembly together with up nozzle and bottom nozzle. In order to reduce the hang-up risk of fuel assemblies during handling, the guide vanes have been set on outer strap, which is an important advance in the structural design of grids. Focused on the hydraulic environment of fuel assemblies in the core, considering the possible transmutation of outer strap caused by the lateral hydraulic force chronically acting on grid during operation, the hydraulic force on outer strap of grid is studied?with CFD method in this paper.Further research and scheme design are also conducted?to reduce the force on outer strap. The results show that the pressure difference between two sides of outer strap will be reduced effectively with the holes set in outer strap, and the effect will be more prominent as the holes move downstream. Meanwhile, increasing?the size of holes will also further?reduce the pressure difference. Moving the holes to dimples will further balance?the pressure between two sides of outer strap, that is, the design of dimples with holes will lower the hydraulic force on outer strap in a greater extent. It is positive to reduce the transmutation of outer strap caused by hydraulic force with the designs above. Thereby, the hang-up risk of fuel assemblies will be reduced during refueling.