Crack propagation in first wall by thermal fatigue and creep

The operation of the international thermonuclear experimental reactor (ITER) is assumed to be a pulsed mode, of which the duration time varies up to 1000 s depending on the experimental condition. If the structural material 316 stainless steel (SS316) of the first wall has a defect, its crack propagation behavior will depend on the duration time. This study deals with the crack propagation behavior on SS316 under high thermal load cycles. The high heat flux tests were carried out on the 5-mm thick specimen under four test conditions in order to investigate the creep behavior on the thermal fatigue. Two-dimensional (2-D) thermal-structure analyses including creep effect were performed to simulate the thermal and residual stress distribution around the crack tip. It was concluded that the creep effect increased the crack propagation length induced by thermal fatigue although the compressive stress occurred around the crack tip during high temperature.