基于ASTEC程序的乏燃料水池严重事故研究

Study on Severe Accident Occurred in Spent Fuel Pool Based on ASTEC Code

为了更深入地理解核电厂乏燃料水池严重事故的进程和后果,基于ASTEC程序建立了某型三代核电机组乏燃料水池严重事故分析模型,根据该模型,分别对正常运行,正常换料和异常换料三种不同运行状态下的长期丧失电源(SBO)和长期丧失电源叠加冷却管线破口(SBO+LOCA)所导致的严重事故进行了分析。分析结果表明,乏燃料水池事故进程相对缓慢,有较大的时间窗口来进行应对。而当乏燃料组件发生裸露和损伤后,将产生大量的氢气和释放大量的裂变产物。通常来说,电厂设计中没有相应的缓解措施能够应对这种情况。此外,在本文研究过程中,还发现了ASTEC程序在模拟乏燃料水池的一些程序特点。

In order to better understand the process and consequences of nuclear power plant(NNP)spent fuel pool severe accident,severe accident analysis model based on ASTEC code for one of third generation NNPs spent fuel pool is established.According the model,loss of cooling(SBO)and loss of coolant inventory with loss of cooling(SBO+LOCA)are analysed in different conditions that are normal operation condition,normal refuelling condition and abnormal refuelling condition respectively.The results show that the progression of accident in spent fuel pool is quite slow and there is a lot of time to respond and mitigate.However,the hydrogen production is extremely high and the radioactive releases are extremely high which is un-acceptable to workers and public after the fuel assemblies are uncovered and damaged.No mitigation measures are in general available to handle such severe consequences.Moreover,the features of ASTEC code to model the spent fuel pool severe accident is also discovered during this study.