Flow blockage of the fuel assembly in the lead-based fast reactor (LFR) may produce critical local spots, which will result in cladding failure and threaten reactor safety. In this study, the flow blockage characteristics were analyzed with the sub-channel analysis method, and the circumferentially-varied method was employed for considering the non-uniform distribution of circumferential temperature. The developed sub-channel analysis code SACOS-PB was validated by a heat transfer experiment in a blocked 19-rod bundle cooled by lead-bismuth eutectic. The deviations between the predicted coolant temperature and experimental values are within ±5%, including small and large flow blockage scenarios. And the temperature distributions of the fuel rod could be better simulated by the circumferentially-varied method for the small blockage scenario. Based on the validated code, the analysis of blockage characteristics was conducted. It could be seen from the temperature and flow distributions that a large blockage accident is more destructive compared with a small one. The sensitivity analysis shows that the closer the blockage location is to the exit, the more dangerous the accident is. Similarly, a larger blockage length will lead to a more serious case. And a higher exit temperature will be generated resulting from a higher peak coolant temperature of the blocked region. This work could provide a reference for the future design and development of the LFR.

铅基快堆（LFR）中燃料组件的流动阻塞可能会产生关键的局部点，这将导致包壳失效并威胁反应堆安全。本研究采用子通道分析法分析流动阻塞特性，考虑周向温度分布不均匀，采用周向变化法。开发的子通道分析代码 SACOS-PB 通过在由铅铋共晶冷却的封闭 19 棒束中进行的传热实验得到验证。预测的冷却液温度与实验值之间的偏差在 ±5% 以内，包括小流量和大流量阻塞情况。对于小堵塞情况，周向变化法可以更好地模拟燃料棒的温度分布。基于验证的代码，进行了阻塞特性分析。从温度和流量分布可以看出，大的堵塞事故比小事故的破坏性更大。敏感性分析表明，堵塞位置越靠近出口，事故的危险性越大。同样，更大的阻塞长度会导致更严重的情况。并且由于阻塞区域的更高峰值冷却剂温度将产生更高的出口温度。该工作可为未来LFR的设计和开发提供参考。敏感性分析表明，堵塞位置越靠近出口，事故的危险性越大。同样，更大的阻塞长度会导致更严重的情况。并且由于阻塞区域的更高峰值冷却剂温度将产生更高的出口温度。该工作可为未来LFR的设计和开发提供参考。敏感性分析表明，堵塞位置越靠近出口，事故的危险性越大。同样，更大的阻塞长度会导致更严重的情况。并且由于阻塞区域的更高峰值冷却剂温度将产生更高的出口温度。该工作可为未来LFR的设计和开发提供参考。