Thermal fatigue of DEMO first wall due to pulsed operation

The effect of pulsing on the first wall of a future fusion power plant is manifested mainly as thermal fatigue of the structure. Due to pulsing the temperature cycles result in varying stress in the first wall which is lifetime limiting as opposed to a steady-state mode where the number of heat-up-cool-down cycles is negligible. A series of analyses have been carried out on a “generic” DEMO outboard first wall using different parameters. The estimated lifetime from thermal fatigue point of view has been calculated. Both water and helium cooling have been considered. The effect of wall thickness between the channels and the front face as well as the coolant inlet temperature has been investigated and compared for both coolants.