小型模块化快堆中含铪控制棒的设计与分析

快堆一般采用以碳化硼（B4C）为吸收剂的控制棒进行反应性控制。小型模块化快堆中子泄漏率较大，增殖能力偏弱，单位燃耗反应性损失较大。模块化反应堆运行周期较长，且需要紧凑型堆芯设计，控制棒数量有限。因此，小型模块化快堆需要高10B富集度的B4C进行反应性控制。由于吸收剂燃耗深、功率密度高且导热能力受辐照削弱严重，B4C的安全使用寿命有限。本文通过对比硼化铪（HfB2）、氢化铪（HfH162）和传统B4C为吸收剂的控制棒的反应性价值、堆芯功率分布、堆芯反应性反馈系数、控制棒温度裕度与吸收剂燃耗深度，发现HfB2有更高的安全裕度和更长的安全使用寿命。HfH162控制棒略微改善了功率分布，但其高温氢气解离问题有待进一步研究。

Design and Analysis of Control Rod with Hafnium-based Absorber Material in Small Modular Fast Reactor

Fast reactors usually use the boron carbide (B4C) based control rods as reactivity control systems. The small fast reactors exhibit strong neutron leakage, hence a low breeding capability and important burnup reactivity loss. The modular reactors require large operating cycle length and compact core design that lead to limited installation space for control rods. Therefore, small modular fast reactors require high 10B enriched B4C in reactivity control systems. Due to the large burnup, high power density and degradation of thermal conductivity under irradiation in absorber, the safe operating time of high 10B enriched B4C is not sufficient to support the small modular reactor. The reactivity worth, core power distribution, reactivity feedback coefficients, control rod temperature margin and absorber burnup of hafnium diboride (HfB2), hafnium hydride (HfH162) and B4C based control rods were assessed in this study. It is founded that HfB2 based control rods exhibit larger safety margin and longer available operating lifetime. HfH162 is able to improve the core power distribution, while its hydrogen desorption effect should be strictly investigated in the future.