CONTROL ROD DAMPING SYSTEM

A damping area or 'dash pot' on the upper ends of control rods absorb energy from dropped control rod assemblies without narrowing the diameter of guide tubes. As a result, coolant can freely flow through the guide tubes reducing boiling water issues. The dampening area reduces a separation distance between an outside surface of the control rod and an inside surface of the guide tubes deceleratingthe control rods when entering a top end of the guide tubes. In another example, the dampening area may be located on a drive shaft. The dampening area may have a larger diameter than an opening in adrive shaft support member that decelerates the drive shaft when dropped by a drive mechanism. 控制棒的上端部上的阻尼区域或"减震器"吸收掉落的控制棒组件的能量，而不会缩小引导管的直径。结果，冷却剂可以自由地流过引导管，从而减少沸水问题。阻尼区域减小了控制棒的外表面和引导管的内表面之间的分离距离，以便当进入引导管的顶端时使控制棒减速。在另一个示例中，阻尼区域可以位于驱动轴上。阻尼区域可以具有比驱动轴支撑构件中的开口更大的直径，以便在驱动轴通过驱动机构下降时使驱动轴减速。