Fabrication of an ITER middle-scaled shielding blanket module mock-up

In the present ITER shielding blanket design, the first wall (FW) has built-in cooling channels (SS316LN) in a copper layer that is bonded to the shielding structure (SS316LN). The shielding structure is a SS block also with cooling channels that are drilled. For fabricating the shielding blanket and the FW, hot isostatic pressing (HIP) has been proposed as a promising joining method to avoid fusion welds under severe neutron irradiation. To demonstrate the fabricability of the FW/blanket, a middle-scaled mock-up was fabricated. The mock-up consists of FW, shielding block, and cooling header, etc. The FW was fabricated using a sandwiched tube technique (DSCu plate and SS316L circular tube), which was composed of a 20-mm thick DSCu heat sink containing SS cooling tubes oriented poloidally. The FW is curved in the poloidal direction corresponding to one of inboard modules (No. 6 module). The cooling channels of the SS316L shielding block were machined by the drilling method. The FW parts (SS tubes and DSCu plates) and the shielding block were bonded by single-step HIPing. After HIP bonding, microscopic observations of bonded interfaces using the remnant (edge of the mock-up) were carried out. Also, to confirm the integrity of pressure boundaries, pressure-resistant and helium leak tests were performed. It has been shown that the middle-scaled mock-up was successfully fabricated using a sandwich-tube technique by single step HIPing.