田湾核电站乏燃料干式贮存临界安全计算研究

摘要

以CASTOR 1000/19干式贮存容器装载田湾核电站六角形乏燃料组件为例,研究六角形乏燃料干式贮存的临界安全问题.基于新燃料假设,应用MONK9A程序对贮存容器满装载乏燃料进行不同工况下keff的计算.计算结果表明:正常工况下,keff远小于临界安全限值,是临界安全的;事故工况下,当235U富集度大于3.15％时,系统存在临界安全风险,须减少乏燃料装载量来确保临界安全.考虑燃耗信任制后,采用相同的模型计算得出贮存容器满装载的参考装载曲线,按此曲线要求装载能确保所有工况下的系统临界安全.采用燃耗信任制技术提高了贮存容器的利用率.该研究可为田湾核电站采用乏燃料干式贮存方案提供依据.%Exampled by the dry storage container CASTOR 1000/19 loading Tianwan Nuclear Power Plant hexagonal spent fuel assembly,the criticality safety of dry storage of hexagonal spent fuel assembly was studied.Based on fresh fuel assumption,the keff of the CASTOR 1000/19 loading hexagonal spent fuel assembly fully was calculated at different conditions by using the MONK9A code.The results show that keff is far less than the critical safety limit under normal condition,i.e.it is safe.When the 235U enrichment is greater than 3.15％,the system has critical safety risk at accident conditions.And the loading capacity had to be reduced to ensure the criticality safety.Considering burnup credit(BUC),a reference loading curve was proposed based on the same calculation model,which could ensure criticality safety.The availability of the storage container increases by adopting BUC.The achievements could be reference for spent fuel dry storage scheme in Tianwan Nuclear Power Plant.