小型堆非能动安全系统初步设计

Preliminary Design of Passive Safety Systems for Small-sized Reactors

非能动安全系统能够极大减轻事故工况下对柴油发电机、水泵等能动设备的依赖,已在第三代核电技术中广泛应用。为进一步提高小型堆的安全性,针对6个非能动安全系统提出初步设计方案。本文使用RELAP5和MELCOR程序建立分析模型,包括主系统、部分二回路系统和安全壳系统,以模拟大破口失水事故工况及全厂断电工况下的堆芯及安全壳响应。结果表明,当前非能动安全系统的协同运行能够有效预防和缓解事故。在大破口失水事故工况下,燃料包壳峰值温度、安全壳压力和温度不会超限,且有较高的安全裕量;全厂断电工况下,压力容器不会被熔穿、安全壳不会发生早期或晚期超压失效,且安全壳内不存在氢气燃爆转变和爆炸的风险。本文提出的设计方案具有一定的工程参考价值。

Passive safety systems can reduce the dependence on active devices,like diesel generators and pumps,under accident condition,and thus are widely adopted in Generation III&III+nuclear power plants.In order to further improve the safety of small nuclear power plants,a preliminary design scheme of six passive safety systems is proposed.Besides,analysis models are established utilizing both RELAP5 and MELCOR code,including the primary system,partial secondary system and containment system,to simulate the reactor core and containment response under LOCA condition and SBO condition.Results show that,the cooperation of passive safety systems mentioned above can prevent and mitigate accidents effectively.Under LOCA condition,the peak fuel-cladding temperature and containment pressure&temperature will not exceed the limiting value,and there is a certain margin of safety.Under SBO condition,the core corium can be cooled inside the RPV,the containment can maintain the integrity in both early phase and late phase,and the hydrogen risks(deflagration to detonation transition and detonation)can be eliminated.The system configuration scheme provided in this paper can be referenced in engineering design.