核电厂大修期间蒸汽发生器U型管返水引发的安全风险及对策

核电厂大修期间,反应堆排水到压力容器法兰面水位后,蒸汽发生器U型管中吸附的水会大量返回到一回路,造成一回路水位控制困难并引发一系列安全风险,对大修人员、设备和反应堆堆芯安全都构成威胁。结合秦山第二核电厂换料大修中蒸汽发生器U型管返水的数据,对蒸汽发生器U型管返水的机理以及带来的安全风险进行了分析,并结合大修工作安排提出了对策。

Safety Risks Caused by Water Return From U-tube of Steam Generator During Overhaul of Nuclear Power Plant and Countermeasures

When the reactor is drained to the flange-face of the pressure vessel during the overhaul of the nuclear power plant,the water trapped in the U-tube of the steam generator returns largely to the primary circuit,making it difficult to control the water level in the primary circuit and cause a series of safety risks,which poses a threat to workers,equipment and reactor core safety.Based on the overhaul data from the overhaul of Qinshan Second Nuclear Power Plant,this paper analyzes the return water mechanism and safety risk,and puts forward some countermeasures according to the arrangement of overhaul work.