安全壳背压对SGTR事故进程的影响研究

Effect of Back Pressure of Containment on SGTR Accident Process

在先进非能动电厂蒸汽发生器传热管破裂(SGTR)事故中,设计上采用非能动余热排出系统来带走一回路热量。分析中使用的安全壳背压的大小会影响到换热器所在换料水箱水沸腾后的温度,并影响到换热器两侧温差进而影响换热效率。本文对换料水箱水沸腾所产生的水蒸气造成的安全壳升温升压效应开展分析以确定SGTR事故过程中安全壳压力进程,确定安全壳压力高值用于SGTR事故分析,并对不同安全壳背压情况下的一回路事故进程进行对比研究,确定安全壳背压对事故进程的影响。分析显示,安全壳背压越高,换热器两侧温差越小,非能动余热排出系统换热能力越弱,采用较高背压将延长事故进程及破口流量终止时间,增大事故下冷却剂释放量,并减小满溢工况下的满溢裕量。

In the advanced PWR SGTR accident, the passive residual heat removal system was designed to remove the decay heat in the RCS with a heat exchanger which is immersed in the RWST. The back pressure of the containment used in the analysis will affect the temperature of the RWST water boiling and the temperature difference between the two sides of the heat exchanger, thus affect the heat transfer efficiency. In this paper, the increasing of the containment pressure and temperature caused by the RWST water boiling is analyzed to determine the containment pressure process during the SGTR accident. A comparative research on the accident process under different containment pressure was conducted to determine the effect of the containment pressure on the accident process. The analysis shows that the higher the back pressure of the containment, the smaller the temperature difference between the two sides of the heat exchanger, and the weaker the heat transfer capacity of the passive residual heat removal system. The higher back pressure will prolong the accident process and the end time of the broken flow, increase the amount of coolant released, and decrease the margin of the overflow.