Abstract
At a tee junction point of piping system, hot water and cold water is mixed with each other in a whirl. The vibrating mixing boundary between the hot and cold water causes a temperature fluctuation on an inside surface of the pipe just after the connection point. The temperature fluctuation yields a cyclic thermal stress near the pipe surface and results in the crack initiation. In the previous study the thermal fatigue tests using disk specimens in simulated BWR environment were performed and the thermal fatigue crack initiation strength was compared with the mechanical fatigue strength. Furthermore the thermal fatigue crack arrest depth was analyzed using the linear fracture mechanics, and the arrest depth was found to be in proportion to the reciprocal root of the frequency of temperature fluctuation, and the experimental results agreed well with the analysis. In this study, the thermal stress distributions in the disk specimen were analyzed using the finite element method, and the thermal fatigue crack initiation behavior, the crack growth and the arrest behavior are discussed.
