Passive residual heat removal systems ensure the safe operation of lead–bismuth fast reactors. However, the resistance of such systems is similar to natural driving forces, while small fluctuations in the surrounding environment and material parameters can cause system failure; thus, analyzing the reliability of passive residual heat removal systems is important for lead–bismuth cooling. This study utilizes the passive system in the lead–bismuth eutectic loop of the TALL-3D experimental facility and proposes a reliability analysis based on t...