Probabilistic fracture mechanics analysis of heat transfer tube in floating nuclear power plant under multiple failure mechanisms

•A probabilistic fracture mechanics integrating Bayesian method failure analysis code is developed.•Failure probability of heat transfer tube in floating nuclear power plant is analyzed.•Multiple failure mechanisms of fatigue and corrosion is investigated.•Uncertainty analysis of input parameters is performed. Floating nuclear power plant (FNPP) is a nuclear plant mounted on a floating platform, designed to power offshore oil and gas drill, island development and remote area. The safety of the facilities is an important issue. Since the heat transfer tube uses seawater as coolant, the leakage of tube will lead to large radioactivity release and serious radioactive consequences to the environment and people, which is also a vital initiating event for reactor probabilistic safety analysis. So a Monte-Carlo-based probabilistic fracture mechanics analysis code is developed to assess the failure probability of a heat transfer tube considering multiple failure mechanisms of fatigue and microbiologically influenced corrosion (MIC). The model simulates crack initiation and crack propagation for large sampling cases, where the crack growth model considers both internal and external surface cracks at the weld. A random shock model is developed to simulate fatigue damage due to wave impacts, and the continue Bayesian network is utilized to model the MIC crack growth. The results show that wave impacts is a major cause of tube failure, and the multiple failure mechanisms increase the double-ended break probability more significantly. Sensitivity analysis indicates that failure probability is more sensitive to the initial crack depth than circumferential length.