Creep-fatigue endurance of a superheater tube plate under non-isothermal loading and multi-dwell condition

Raising the operating temperature to increase electricity production in the nuclear power industry is a practical solution in the aspect of efficiency and emissions reduction. However, regarding structural integrity, such high temperature has a significant impact on the life of nuclear power plant components. The superheater tube plate is one of the most critical parts under exposures of very high temperature in the boiler system of the power plant. This study investigates creep-cyclic plasticity behaviour of a superheater outlet tube plate under extremely sophisticated thermo-mechanical loading and evaluates creep-fatigue damage endurance, using the modified LMM eDSCA. Temperature-dependent material properties are employed to calculate more practicable structural behaviour and lifetime prediction. The results clearly present the criticality of the effects of non-isothermal loading and multiple dwells on the structural integrity of the tube plate. Also, this study clarifies critical factors that cause dominant damage to the tube plate by providing total damages using various damage assessment models, of which results show the trend of the conservativeness of each damage assessment model, compared to experiment result.