Development of high cycle thermal fatigue evaluation method based on time interval of peak-to-peak of fluid temperature

Kimura, Nobuyuki; Kobayashi, Jun ; Kamide, Hideki 

In JSFR, the temperature fluctuation at the core outlet region does not have always a sinusoidal waveform but a sharp edged waveform. The temperature shows intermittent and sudden decrease and recovery like a spike form. In this study, the time interval of each wave based on the rainflow method was applied to consider frequency characteristics against the conversion from fluid temperature to thermal stress in structure. The thermal stress obtained from the new method was compared to the results of FEM analysis. It was found that the consideration of frequency characteristics of waves could evaluate the fatigue damage in structure. Furthermore, the frequency characteristics of waves in this method were expressed as the unified curve independent of the velocity. Hereby the new evaluation method could evaluate the thermal fatigue in the reactor.