AbstractThis paper presents the main results obtained so far from the development work performed in Europe to define the joining conditions between beryllium (Be) tiles and the dispersion strengthened copper alloy (DS-Cu) heat sink material for the ITER primary first wall (PFW). Two Be/DS-Cu joining techniques were investigated: hot isostatic pressing and furnace brazing. Six PFW mock-ups have been thermal fatigue tested so far. One PFW mock-up with HIPped Be tile was tested at 2.5 MW/m2 for 1000 cycles without any indication of failure. On two other mock-ups, Be tiles detached at or above 2.7 MW/m2. Two others were tested at 0.7 MW/m2 for 13 000 cycles also without any indication of failures. A first PFW mock-up with a furnace brazed Be tile was tested at 1.6 MW/m2 for 1000 cycles. These results should be compared with the operation conditions of the ITER PFW, namely 0.5 MW/m2 peak heat flux and off-normal events up to 1.4 MW/m2. Thermal fatigue testing of other mock-ups is still in progress and the development programme is continuing to further increase the engineering margins while decreasing the fabrication cost of the PFW panels.