小型堆严重事故下安全壳内氢气行为分析

采用MELCOR程序,对小型堆破口叠加全部电源丧失的典型严重事故进行计算,并对安全壳内发生氢气燃烧、爆炸的可能性进行分析。结果表明:主管道直径3.72%的破口叠加全部电源丧失后,堆芯裸露,出现熔堆事故;同时锆水反应产生的大量氢气进入安全壳,使安全壳内氢气含量上升,在安全壳局部空间、屏蔽水箱内出现氢气燃烧。但由于小型堆安全壳净容积较小,水蒸气含量较高,氧气含量较少,不会导致氢气爆炸。

Analysis of Hydrogen Combustion and Explosion for Serious Accident of Small Reactors

Using MELCOR code,the combination of LOCA and blackout accident sequence in small reactors under full power operation was calculated,and the probability of hydrogen combustion and explosion was analysed.The results show that these severe accidents lead to the bareness of the reactor core and the CMAs at last.At the same time hydrogen produced by zirconium and water reaction leaks and increases in the containment,so hydrogen combustion will happen at local space of the containment and the block tank.But hydrogen explosion will not happen as the high mole fraction of the steam and low mole fraction of oxygen in small volume of the containment.