目的 在开展二氧化铀(UO2)芯块运输容器设计时，应进行临界安全分析，优化容器设计，并通过得出的临界安全指数(CSI)限定可运输货包的数量，确保在任何可信的运输情景下的核临界安全。方法 文中采用蒙特卡罗软件SuperMC对符合要求的国际临界安全手册中6类49个基准实验案例进行建模计算，获得本案例的次临界上限值，再基于运输容器经受正常运输条件与运输事故条件试验的结果，计算得出正常运输条件与运输事故条件下的单货包与货包阵列的最大中子增殖系数keff值。结果 该案例的次临界限值(USL)为0.919 74;UO2芯块运输容器在正常运输条件与运输事故条件下单货包的最大keff值分别为0.286 08，无限阵列货包的最大keff值为0.798 34。结论 UO2芯块运输容器在正常运输条件与运输事故条件下的最大keff值均小于0.919 74，临界安全指数为0，容器设计临界安全性能可确保可运输安全。

Nuclear criticality safety analysis is an important part of the design safety evaluation of radioactive material transportation containers. During the design of UO2 pellets transport container, criticality safety analysis shall be carried out, and the number of transportable packages shall be limited by the calculated criticality safety index (CSI), to ensure nuclear criticality safety under any credible scenario. In this paper, the Monte Carlo software SuperMC is used to verify the 49 benchmark test cases in 6 categories in the international criticality safety manual, and the maximum upper subcritical limit (USL) of this case is 0.919 74. Based on the test results of the transportation container under normal conditions and accident conditions, the maximum keff values of single package and package array under normal conditions and accident conditions are calculated. The calculation results show that the maximum keff value of single package is 0.28608, and the maximum keff value of infinite array package is 0.798 34. The maximum keff values of UO2 pellets transport container under normal transport conditions and transport accident conditions are both less than 0.919 74. The criticality safety index is 0 for those values are lower than the USL. The container design critical safety performance can ensure the critical safety during transportation.