大功率非能动压水堆DVI管破叠加IRWST失效触发严重事故分析

应用MELCOR 2.1程序,建立了大功率非能动压水堆核电厂主要回路系统及安全壳的热工水力模型,并以直接注水管线破口叠加内置换料水箱失效触发严重事故为对象进行了独立计算。计算结果与MAAP 4.04程序计算结果趋势一致,分析表明:MELCOR 2.1新版本对严重事故计算合理可信;部分非能动安全设施的启动有效地降低了主回路系统压力,防止高压熔堆,缓解了堆芯熔化进程,从而验证了非能动安全设施的有效性。

Analysis of Severe Accident Initiated by DVI Break Coupled with IRWST Failure for Large Power Passive PWR

The thermal-hydraulic models of main loop system and containment compartments had been built using MELCOR 2.1 code for Large Power Passive PWR. And by this code,calculations of severe accident scenarios initiated by DVI pipe small break with failure of Internal Refueling Water Storage Tank (IRWST) had been performed. The calculation results matched well with the results calculated by MAAP 4.04 code. The analysis results showed that: (1) the simulation results of severe accidents using MELCOR 2.1 code are reasonable and reliable;(2) the successful operation of parts of passive engineering safety features triggers the depressurization of the primary loops effectively,reduces the risk of high-pressure core melt,mitigates the melt progression in the core region,and validates the effectivity of the passive engineering safety features.