先进压水堆大破口失水事故耦合特性研究

Study on Coupling Characteristics of Large Break LOCA in Advanced PWR

先进压水堆采用非能动安全壳冷却系统作为事故后安全壳排热手段,事故后以钢安全壳为换热面将释放到安全壳的能量传递到环境中。失水事故后非能动安全壳冷却系统带热能力的好坏关系到整个反应堆的安全,事故进程中反应堆冷却剂系统的非能动特性与安全壳的非能动特性相互耦合,需要将非能动安全壳冷却系统和反应堆冷却剂系统进行耦合分析,了解事故后反应堆冷却剂系统与安全壳的耦合特性。本文通过开展大破口失水事故下反应堆冷却剂系统和安全壳的耦合分析,了解各非能动系统在大破口失水事故工况下的耦合特性。分析结果显示:大破口失水事故下,耦合分析中非能动余热排出系统、非能动堆芯冷却系统、自动卸压系统和非能动安全壳冷却系统的特性尤其是非能动余热排除系统排热功率、内置换料水箱注入时机和流量、自动卸压阀流量、安全壳压力温度等均与单独计算有较大差异,大破口失水事故下耦合分析得到的事故前期安全壳压力、温度峰值小于单独计算,事故后期安全壳压力在地坑水蒸发的作用下会逐步高于单独计算结果。

Advanced pressurized water reactor adopts passive containment cooling system as a means of heat removal from containment after an accident using the steel containment as a heat transfer surface.The heat removal capacity of the passive containment cooling system after loss of coolant accident(LOCA)is related to the reactor safety.The passive characteristics of the reactor coolant system and the containment are coupled to each other during the accident.It’s necessary to perform coupling analysis to understand the coupling characteristics of the reactor coolant system and the containment after the accident.In this paper,the coupling analysis in a large break LOCA(LBLOCA)is conducted to understand the coupling characteristics of each passive system.The analysis results show that the characteristics of the passive residual heat removal system,passive core cooling system,automatic pressure relief system,and passive containment cooling system in the coupled analysis are significantly different from the independent calculations,the containment pressure and temperature peaks are lower than the independent calculation in the early phase of the accident,the containment pressure in the later phase of the accident will gradually be higher than the independent calculation result due to the evaporation of containment sump water.