The ITER project is considering two shield module design options (A and B) for the shield blanket, as described in the Final Design Report issued in July 2001. The outer dimensions of the modules and the interfaces to the rest of the machine are the same for both options. The difference arises from the type of panel-to-shield attachment system used, which has implications for the detailed design of the components. For option A, studied in detail by the EU and shown in the figure below, the Primary First Wall (PFW) panels are attached to the shield block by a poloidal row of studs made from a high strength nickel-based alloy. These are located on a central poloidal key, which is also used as the electrical contact with the shield to minimise the current flowing through the studs. This central location for the electrical contact reduces the electromagnetic loads on the attachment system.

Two Hot Isostatic Pressing (HIPping) methods are being considered for the fabrication of the bi-metallic structure of the PFW panels. With solid HIPping, the stainless steel (SS) backing plate, the copper alloy plates and the SS tubes are joined together with one single HIP cycle at 1040 °C. With powder HIPping, a first HIP cycle at 1100 °C is used to consolidate the SS powder with embedded SS tubes. A second HIP cycle at 1040 °C is then performed for consolidating and joining the Cu alloy powder. Beryllium (Be) tiles are finally joined by HIPping or brazing as shown in the table below.

ITER shield blanket:
comprises 421 modules (404 regular modules, 17 Neutral Beam Injector modules)

Shield module:
consists of one shield block (316L Stainless Steel) and 4-8 separable Primary First Wall (PFW) panels.

PFW panel:
is a bi-metallic structure with a 316L Stainless Steel backing plate and a Copper alloy heat sink layer (CuCrZr or CuAl25 alloy). Beryllium (Be) armor tiles are joined to the Cu alloy heat sink.

An R & D programme is in progress to demonstrate the manufacturing feasibility of these panels and to select the best fabrication method for the ITER Blanket procurement. Three full scale panel prototypes have already been completed (panels 1 to 3 in the table). Two more are under fabrication. All of these panels will be thermal fatigue tested to confirm the good results already obtained with PFW mock-ups. The fabrication method to be used for the series production will be selected after analysis of the thermal fatigue test results and after a comparative and detailed fabrication cost assessment.