不同类型核燃料对热管冷却反应堆燃耗性能的影响

热管冷却反应堆采用固态反应堆设计理念，具有功率密度高、结构紧凑、固有安全性高等特点，在深空探索、深海勘探、偏远地区等场景中具有广阔的应用前景。核燃料作为热管冷却反应堆的重要组成部分，不同类型核燃料在堆芯燃耗分析时会呈现不同的中子学性能。基于美国爱达荷国家实验室(INL)提出的热管冷却反应堆INL Design A，利用清华大学蒙特卡罗中子输运程序RMC (Reactor Monte Carlo code)建立堆芯物理模型，选取UO₂，(U_0.9Pu_0.1)O₂，U-10Zr，U-8Pu-10Zr，UN，UC这6种核燃料开展燃耗计算，分析了不同核燃料、不同功率水平对热管冷却反应堆堆芯燃耗性能的影响。计算结果表明:在堆芯燃耗深度相同情况下(20.8 GW·d·t?1)，装载U-8Pu-10Zr燃料的堆芯所需235U富集度最低(9.8%)，具有较好的U-Pu增殖性能。堆芯功率处于5 MW的热管冷却反应堆，燃料中241Pu的存在不仅没起到增大堆芯燃耗深度的作用，反而导致堆芯剩余反应性和堆芯寿期末次锕系核素(MAs)的产量增大，影响反应堆的安全性与经济性。因此，对于装载含有Pu燃料的小功率长寿期热管冷却反应堆，需重点关注241Pu对堆芯燃耗性能的影响。

Influence of different types of nuclear fuel on burnup performance of heat pipe cooled reactor

The heat pipe cooled reactor adopts the solid-state reactor design concept, and it has the characteristics of high power density, compact structure and high inherent safety. It has been extensively used for deep space exploration, deep sea exploration, remote areas electricity markets and other scenarios. Nuclear fuel is an important part of the heat pipe cooling reactor, different types of nuclear fuel will reflect different neutronics performance on the reactor burnup analysis. In this paper, based on the heat pipe cooled reactor INL Design A proposed by the Idaho National Laboratory (INL), the burnup calculation is done by selecting six nuclear fuels : UO₂, (U_0.9Pu_0.1)O₂, U-10Zr, U-8Pu-10Zr, UN and UC. The effects of different nuclear fuel and power levels on the burnup performance of heat pipe cooled reactor core were analyzed. The calculation results show that under the same core burnup depth (20.8 GW·d·t?1), the core loaded with U-8Pu-10Zr fuel requires the lowest 235U enrichment (9.8%), and has better U-Pu breeding. For the heat pipe cooling reactor with the core power of 5 MW, the presence of 241Pu in the fuel does not increase the core burnup depth, but leads to the increase of residual reactivity of the core and the yield of the secondary actinides nuclides (MAs) in the core end of life, which affects the safety and economy of the reactor. Therefore, for the low-power and long-life heat pipe cooled reactor loaded with Pu fuel, it is necessary to focus on the influence of 241Pu on the core burnup performance.