Joining methods of Be/FMS and W/FMS for the ITER TBM first wall

Be and W joints with ferritic–martensitic steel (FMS) were fabricated using a hot-isostatic pressing (HIP) bonding method. Be was joined on Cu or Ti explosive welded FMS. W was joined with the insertion of Ti films between W and FMS. HIP processing conditions were 100 MPa at 580 °C for 2 h for the Be/FMS mock-ups, and 100 MPa at 900 °C for 1.5 h for the W/FMS joints, respectively. Joining interlayers such as Ti, Cr, Cu were used to minimize the adverse diffusion of Be and W that can induce the brittle fracture of the joints. The fabricated Be/FMS test blanket module first wall mock-ups revealed a high joining strength of 167–177 MPa in shear stress, and demonstrated successful a high heat flux performance up to 1000 cycles at 0.5 MW/m2.