基于故障树分析法的乏燃料水池失去冷却事件分析

Analysis of event due to loss of spent fuel pool cooling based on fault tree analysis method

国内某核电厂1号机组发生了操纵员错误关闭1RRI公用负荷隔离阀导致乏燃料水池失去冷却的运行事件,本文运用故障树分析法对该事件原因进行分析。通过梳理事件序列,确定事件过程中的主要失效点,作为故障树最上层的顶事件,从顶事件出发,不断查找故障树上一层失效的原因,找出导致主要失效点的深层次原因。最终确定事件发生的根本原因是:操纵员试验准备、工作技能不足,且操作过程中未采取自检或其他防人因失误的方法;机组长屏障失效,未对操纵员提供有效的监护和支持;核电厂对重大高风险活动的准备和管控不足。最后提出针对性的改进建议。

The event occurred in a domestic nuclear power plant due to loss of spent fuel pool cooling caused by mistakenly closing 1RRI isolation valve to common load,and the root cause was analyzed by using fault tree analysis method.The main failure point of the event process was determined by establishing the sequence of event,which was treated as the top event of the fault tree.From the top event,the cause of the failure of the upper level of the fault tree was continuously investigated,then deep cause was found out,and finally the root causes of the event were determined that the operator was lack of test preparation and work skills,and no self-checking or other protections from human errors were taken during the operation.The barrier of chief failed and no effective guardianship or support from chief was provided for the operator.Preparation and control for major high-risk activities was insufficient.Finally,some proposals for improvement were given.