核电站LOCA释放源项的模拟计算

Simulation Calculation of Source Term Released During LOCA

文章在对轻水堆核电站先进堆型AP1000失水事故(LOCA)的事故进程分析的基础上,明确了失水事故堆芯释放源项的核素类型,再基于《AP1000设计手册》中提供的基础设计数据,利用ORIGEN2编程对关注的核素进行计算,求取各核素在0～8 h内放射性活度随时间的变化。并将计算结果与设计值进行对比分析,从结果来看,大部分核素的计算值与设计值数量级基本吻合,部分核素的计算值与设计值之间存在1～2个数量级的差异,这是因为在源项选择中忽略了部分核素,此外,选取的堆芯放射性核素的积存量为保守的基准设计值。核电站应当加强对碱金属、惰性气体和碘的关注。在事故前期,碱金属138Cs约占总放射性的85.6%;事故后期,则是惰性气体133Xe占比最大,约为53.1%。

Based on the analysis of how the accident happen and proceed,to identify the forms of the source terms released during the accident,then to use ORIGEN2 programming to calculate the radionuclides concerned so to get how the radioactivity of the radionuclides change during 8 hours after the accident occur by data provided in the AP1000 Design Manual.Then,comparing the calculated results to the design values.The results show that values of most nuclides calculated are in good agreement with the design values,and there are 1~2 orders of magnitude difference between the calculated values and design values of some nuclides,which is because the fact that some nuclides are neglected when selecting the source terms and that the inventory of radionuclides selected is a conservative design value.Nuclear power plants should pay more attention to alkali metals,noble gases and iodine.In the early stage of the accident,138 Cs accounts for about 85.6%of the total radioactivity.In the later stage of the accident,the ratio of 133 Xe is the largest,which is about 53.1%of the total radioactivity.