钍基柱状高温气冷堆不同启动燃料特性初步分析

钍是一种可转换材料，将其转换成²³³U能极大提高现有核燃料资源的储量。为实现对钍的合理利用，以模块式柱状高温气冷堆GT-MHR的燃料组件作为研究对象，选取低浓缩铀、武器级钚、核反应堆级钚等作为其启动燃料。利用栅格输运计算程序DRAGON对这3种启动燃料下的钍基柱状燃料组件的寿期初中子能谱、无限增殖系数、燃耗、转换比以及²³³U和²³²Th的含量等参数进行了分析。结果表明，在易裂变物质初装量约为9%时，与低浓缩铀和武器级钚相比，核反应堆级钚作为启动燃料时组件寿期初中子能谱较硬、转换比较高；其燃耗达90 GW•d/tHM；其无限增殖系数在寿期内的波动最小；燃耗为75 GW•d/tHM时组件中²³³U存余量与²³²Th消耗量之比达0.566。

Preliminary Analysis of Different Driver Fuels in Thorium-Based Prismatic GT-MHR

Thorium is a fertile material and is converted into ²³³U in nuclear reactors, which could greatly improve existing reserves of nuclear fuel resources. In order to use thorium, block-type modular high temperature gas-cooled reactor GT-MHR was studied, and low-enriched uranium, weapon-grade plutonium and reactor-grade plutonium were chosen as the driver fuels for the thorium based GT-MHR. The lattice transport code DRAGON was used to analyze the characteristics of the prismatic fuel block, including the neutron energy spectrum at beginning of life, infinite multiplication factor, fuel burnup, conversion ratio, and the mass of ²³³U and ²³²Th. The analysis shows that when the mass fraction of the initial fissile material is close to 9%, compared with the low-enriched uranium and weapon-grade plutonium, the reactor-grade plutonium has the hardest neutron energy spectrum at beginning of life and high conversion ratio, and reaches a burnup of 90 GW•d/tHM, and achieves the minimum reactivity swing during the fuel cycle. Moreover, the ratio of remaining ²³³U to the consumption of ²³²Th reaches 0.566 at a burnup of 75 GW•d/tHM.