钍基气冷快堆中^233U与^239Pu的增殖性能研究

Analysis of breeding performance for thorium-based gas-cooled fast reactor started by ^233U and ^239Pu

气冷快堆作为第四代核能系统国际论坛选定的堆型之一,兼具高温气冷堆和快堆的优势,有较高的增殖性能,理论上有高增殖率和短燃料倍增时间等特性。采用SCALE6.1程序中的TRITON模块,使用不同易裂变核素启动钍基气冷快堆并进行燃耗分析,研究燃耗过程中易裂变核素的演化特性。首先分析增殖比和易裂变核素随燃耗变化,并针对气冷快堆特性进行易裂变核素增殖性能的加权分析,获得加权后的增殖增益;然后对比使用增殖比和加权的增殖增益两种不同评价方法时倍增时间的差异;最后使用等效启堆方法对倍增时间进行优化分析。结果表明:分析不同易裂变核素加权后的增殖性能以及等效消除质量差异后的倍增时间,可以更准确描述快堆增殖特性,可以为钍基气冷快堆的换料方案提供参考。

[Background]As one of the reactor types selected by the fourth generation nuclear energy system international forum,gas-cooled fast reactor has the advantages of high temperature gas cooled reactor and fast reactor,with high breeding rate and short fuel-doubling time.[Purpose]This study aims to analyse the neutronic characteristics of different fissile nuclides in operation using the TRITON module in SCALE6.1.[Methods]Firstly,the changes of breeding rate and fissionable nuclides with burnup were analyzed.The breeding performance of fissionable nuclides was weighted according to the characteristics of gas-cooled fast reactor.Then,the difference of doubling time between two different evaluation methods of breeding rate and weighted breeding gain were compared.Finally,the doubling time was optimized by using an equivalent start-up method.[Results&Conclusions]The results show that the analysis of the doubling time of different fissionable nuclides using weighted breeding gain and equivalent elimination mass difference can describe the breeding characteristics of fast reactors more accurately,providing a reference for the refueling scheme of thorium-based gas-cooled fast reactor.