用于支持PSA成功准则的ATWS敏感性研究

极限的未能紧急停堆的预期瞬态（ATWS）是核电厂二次侧热移出能力减小引起的升温瞬态。为评价AP1000核电厂在发生ATWS事故后的响应，采用LOFTRAN程序对极限的丧失主给水ATWS进行计算分析。对影响电厂系统响应的一些关键因素，如蒸汽旁排的容量、堆芯补水箱（CMT）特性和硼反应性系数、反应堆冷却剂泵（RCP）可用性、启动给水系统（STS）可用性和蒸汽发生器（SG）传热等作了一系列敏感性分析。分析结果表明：为缓解ATWS事故，应隔离蒸汽旁排，并在触发CMT的同时停运RCP。

ATWS Sensitivity Studies to Support PSA Success Criteria

The limiting anticipated transient without scram (ATWS) event is the heatup transient caused by a reduction of heat removal capability by the secondary side of the plant. In order to evaluate the AP1000 plant behavior following an ATWS, loss of normal feedwater ATWS event has been analyzed using the LOFTRAN code. Several sensitivity studies are also performed to address some key issues, such as steam dump capacity, core makeup tank (CMT) characteristic and boron coefficient, reactor coolant pumps (RCPs) availability, startup feedwater system (STS) availability and steam generator (SG) heat flux. The results of the analysis show that in order to mitigate the consequence of such an accident, the steam dump should be isolated and RCP should trip on CMT actuation signal.