长寿命小型自然循环铅基快堆燃料选型

针对铅基快堆长寿命、小型化、自然循环的设计目标，构建铅基快堆堆芯模型并开展燃料选型研究，选取U-Pu、Th-U循环燃料及氧化物、氮化物、碳化物、金属燃料，分析比较了不同燃料的物性参数、在不同能谱条件下的堆芯物理特性。结果表明：在偏软能谱中，Th基燃料堆芯增殖能力更强，反应性系数负值更大，热工安全裕量更大、裂变产物容留能力更强；PuN-ThN燃料堆芯燃耗特性最佳，可在较疏松栅格条件下获得较强增殖能力，减少燃料装载量，确保固有安全性，兼顾堆芯长寿命、小型化、自然循环设计要求；但堆芯有效缓发中子份额较小，不利于反应性控制。

Fuel Selection of Long Life Small Natural Circulation Lead-based Fast Reactor

Aiming at design goals for long life, miniaturization and natural circulation of lead-based fast reactors, a lead-based fast reactor core model was constructed and fuel selection was carried out. U-Pu and Th-U cycle fuels, oxides, nitrides, carbides and metal fuels were selected to be researched, and the physical parameters of different fuels, the physical characteristics of cores under different energy spectra were analyzed and compared. The results show that in the soft energy spectrum, Th-based fuel core has the larger breeding ratio, and the larger negative reactivity coefficient, the larger thermal safety margin and the stronger fission product retention capacity. PuN-ThN fuel core has the best burnup characteristics, can obtain the higher breeding ratio under loose grid conditions, reduce fuel load, ensure inherent safety, and meet the design requirements of long core life, miniaturization and natural circulation; however, the effective delayed neutron fraction of the core is small, which is not conducive to reactivity control.