余热排出系统安全壳外破口事故源项分析

当余热排出(RHR)系统入口管道在安全壳贯穿件下游发生断裂时,放射性核素随一回路冷却剂的排放直接释放到环境中。本文根据RHR系统安全壳外破口事故的特点,提出了一套评估放射性后果的计算方法。同时,评估了在不同的RHR系统隔离时间下的放射性后果。根据计算结果和GB 6249—2011的要求,选择300s作为发生该类事故后隔离RHR系统的限值,为我国自主化第三代核电厂RHR系统隔离方案设计提供一个设计基准。

Accident Source Term Analysis of Residual Heat Removal System Break outside Containment

When the inlet pipe of the residual heat removal (RHR) system ruptures on the dow nstream of the containment isolation valve , the radionuclides in the primary coolant release to the atmosphere directly .A method to assess the radiological conse‐quence of this accident was given in this paper according to the accident process .In addi‐tion ,calculation results were given with different assumptions of the isolation time of the broken RHR system .The results show that 300 s can be chosen as the limiting time ,as one of the design basis of the RHR isolation system for Chinese generation Ⅲnuclear power plant , according to the calculation results and the requirement of GB 6249—2011 .