核电厂旁路阀振动致螺栓断裂原因分析

Analysis of Bolt Fracture Caused by Bypass Valve Vibration in Nuclear Power Plant

某核电机组在汽轮机启动过程中,旁路阀发生剧烈振动,导致阀体与油动机之间的连接螺栓全部断裂。通过分析机组启动过程中产生剧烈振动时的负荷、油动机的动作曲线,结合阀门解体后阀体上与阀芯接合面的情况,研究阀门的结构及在各负荷时阀芯与阀体套筒的相对位置,给出阀门振动致螺栓断裂的原因,即:重约300 kg的阀芯在5 mm预启行程内往复运动,撞击预启阀的阀芯,23 min后达到螺栓疲劳断裂极限,导致4个连接螺栓全部断裂;同时提出相应的改造方案。

During the turbine startup process of one Nuclear Power Plant,the bypass valves vibrated severely,even to break all of the connecting bolts between the valve bodies and the oil-driven actuator.In this paper,a careful analysis of the unit load during severe vibration and the motion curve of the oil-driven actuator,together with the condition of the joint surfaces of the valve bodies and the spools after the split of the valves have been made.Moreover,the authors analyze the structures of the valves and the relative positions between spools and sleeves under different load conditions,and give the origin for the break of the connecting bolts,i.e.,the valve spool of 300kg weight moved back and forth in the pre-inlet travel length and hit the spool,and after 23 min.,the bolts reached the abruption limit and caused four connecting bolts to be broken.In this paper,the recommended modifications are provided.