一回路相关死管段与热分层危害分析

摘要

To avoid dead pipe segment and thermal stratification hazard ,the dead pipe segment and thermal stratification hazards among primary loop related pipes for new type PWR based on experience and nuclear island system design features were analyzed in the paper . Having screened out those pipes in w hich the hazard could occur , the residual heat removal pipe CFX simulation was carried out typically .Final results show thermal stratification temperature distribution and dow nstream pipe segment temperature rising between two isolation valves filled with coolant originally . In conclusion , the residual heat removal pipe meets the requirements of thermal stratification criteria generally , and the dead pipe segment hazard may occur in pipe segment between two isolation valves , but could be prevented by means of layout adjustment . Besides , results show the characteristics of buoyancy recirculation and vortex impingement from primary loop flow on residual heat removal pipe .%为避免死管段与热分层危害，结合有关经验与核岛工艺系统设计特点，对某新型压水堆一回路各连接管逐一进行死管段与热分层危害分析。筛选出危害可能发生的管段后，对其中典型的热段连接余热导出管段应用计算流体力学软件C FX模拟分析，计算达收敛状态后可得出该管段热分层温度分布情况。另外，该管段下游两个隔离阀间封闭管段初始条件设定为充满工质，因受一回路影响而被加热升温，通过该封闭管段工质最终温度结果可判断是否出现死管段现象。最终计算数据显示热段连接余热导出管段总体上满足热分层验收准则，不过下游隔离阀间封闭管段有形成死管段的风险，但通过调整布置等措施可避免死管段危害。结果还显示出浮力循环流与一回路紊流冲击影响的流线特点。