堆芯中子和γ源强计算方法及影响因素研究

Study on Calculation Method of Core Neutron and γ Ray Source Intensity and Influence Factors

中子和γ射线源强是辐射屏蔽设计的基本输入数据,研究堆芯中子和γ射线源强的变化有助于工作人员在维修和换料期间进一步做好辐射防护。论文通过ORIGEN-S调用不同的数据库建立了两种计算反应堆堆芯中子和γ射线源强的方法,对比了计算结果的差异,并分析了燃耗、富集度、比功率、运行方式对计算结果的影响。结果表明：在不同的停堆时间,采用ORIGEN-ARP计算的中子源强略小于采用CARD-IMAGE数据库计算的结果,差值在6%以内;两种方法对不同能群对应的γ射线源强产生的影响不同,且随着停堆时间的延长,影响增大;各因素对堆内中子源强产生了不同的影响,中子源强随燃耗的加深而逐渐增大,随着富集度和比功率的增大而减小,在燃耗相同且运行时间较长的情况下,间歇模式运行产生的中子源强高于连续模式下产生的中子源强40%~50%。

Neutron and photon source intensity are input data for radiation protection shielding calculation,so it could help staff do better radiation protection during the maintenance and refueling to study the changes of neutron and γ ray source intensity in reactor.In this paper,the calculation method with two kinds of databases was studied by ORIGEN-S and the influence factors fuel burnup,enrichment,specific power and operation mode were analyzed.The results indicated that at different shutdown times,the neutron source intensities calculated by ORIGEN-ARP library were slightly less than that by CARD-IMAGE library,the difference was less than6%.The effects of databases on the calculation results of different energy γ ray were different.With increasing of shutdown time,the difference of γ ray source intensity calculated by the two databases grew.The various factors affected the neutron source intensity differently.The neutron source intensity increased with burnup deepening,and decreased as enrichment and specific power increased.In the same fuel burnup and long operation time condition,the neutron source intensity under intermittent operation mode was higher 40%-50% than that under continuous mode.