An actively cooled mock-up with massive tungsten assembled to Eurofer97 tested up to 3 MW/m²

For DEMO reactor, tungsten is considered as armor material. Eurofer97 is planned to be used as structural material for the first wall. The present study shows the results of the non-destructive testing, high heat flux (HHF) testing of an actively cooled mock-up (150 × 25 × 25 mm) with massive tungsten as plasma facing surface material and Eurofer97as structural material, in which water is circulating. The solution for joining is based on the use of three different layers: tantalum (Ta), a mix of Ta and titanium (Ti) and a final layer of Ti. Cold gas dynamic spray process is used to fabricate this functionnal graded material (FGM) constituted of Ti and Ta (Ti/Ta FGM). The final joining between tungsten (W), Ti/Ta FGM (900 µm ±150) and Eurofer97 is achieved using hot isostatic pressing (1040 °C/1400bar/2 h), followed by a thermal treatment to recover Eurofer97 mechanical properties. Infrared thermography and ultrasonic tests were performed after the fabrication of the actively cooled mock-up and emphasized that two-thirds of the mock-up have good bonding quality. This part was tested under high heat flux tests up to 3 MW/m². This mock-up sustained this level of incident heat flux >120 times without enduring particular detrimental damage. The limitation in terms of heat flux applied for this test is imposed by the Eurofer97 maximum temperature above which its mechanical strength is decreased (550 °C).