High heat flux testing of first wall mock-ups with and without neutron irradiation

Highlights: • Determination of thermal performance of neutron irradiated first wall Be mock-ups. • Degradation due to decreasing thermal conductivity of degradation of joint quality. • Variation of damage location and formation for non-irradiated and irradiated mock-ups. • Detachment of neutron irradiated beryllium tiles partially at the Be/Cu interface and by crack deflection into beryllium. - Abstract: Beryllium as the plasma facing material for the first wall of ITER will be exposed to thermal, particle and neutron loads. In the frame of the European qualification program for ITER, two HIPped beryllium small scale flat-tile mock-ups consisting of a steel support structure, a CuCrZr/Cu heat sink and two beryllium tiles on top were manufactured by CEA. One mock-up was exposed to neutron irradiation up to 0.75 dpa in beryllium in the RBT-6 fission reactor at Dimitrovgrad, Russia, while the other one was kept as reference. Furthermore, an identical mock-up was produced in Russia by manufacturing via electron beam induced rapid brazing and also exposed to the same neutron irradiation conditions. For qualification, all three flat-tile mock-ups were exposed to cyclic steady state heat loads in the electron beam facility JUDITH-1 up to a maximum of 3.0 MW/m². Thereby, each tile was loaded individually as the full loading area exceeds the limits of the facility.