SB-LOCA始发严重事故下压力容器内氢气源项分析

Analysis of In-vessel Hydrogen Source Term during Severe Accident Induced by SB-LOCA

针对大亚湾核电站900 MW压水堆,采用一体化严重事故分析工具,对小破口冷却剂丧失(SB-LOCA)始发严重事故进行模拟,分析了不同破口尺寸和破口位置对事故进程及压力容器内氢气产生量的影响。结果表明,压力容器内氢气的大量产生集中在堆芯开始熔化阶段;压力容器内氢气产生量与破口尺寸有关,但没有明显规律,且分布较为集中,氢气平均产生量约为500 kg;破口位置对氢气的产生影响较小。

With an integral severe accident analysis computer code, severe accident sequences induced by small-break loss-of-coolant accident （SB-LOCA） in Daya Bay Nuclear Power Plant （900 MWe PWR NPP） are calculated. The impacts of different sizes and locations on the progression of accident and the generation of the in-vessel hydrogen source term are analyzed in this paper. The results are summarized as follows： A mass of in-vessel hydrogen source generates at oncoming and initial stage of core melting; The amount of in-vessel hydrogen source term is with obscure relation to the break size, and with many different sizes of breaks, the amount of in-vessel hydrogen source term distributes in a small area, and the average amount of the hydrogen production is about 500 kg; The location of break has a small impact on the generation of the hydrogen source term.