Development of residual thermal stress-relieving structure of CFC monoblock target for JT-60SA divertor

•We carried out numerical simulations on residual thermal stress of targets for the JT-60SA divertor.•We developed three measures to reduce residual thermal stress.•We proposed two structures of CFC monoblock target for the JT-60SA divertor.•We confirmed the effectiveness of the structure by infrared thermography inspection and high heat flux test.