Manufacturing and testing of a relevant scale mockup based on monoblock concept

The results obtained from small-scale mockups manufactured on the monoblock design concept have proven that the solution appears promising for a conventional divertor operating with heat fluxes in the range 10 to 15 MW/m/sup 2/ with a thermal fatigue cycle exceeding 1000 cycles at full power. The concept developed in laboratory-scale brazing tests and the results of component design optimization have been implemented in a larger multi-tube mockup with the following goals: (a) to demonstrate the possibility of manufacturing defect-free industrial components on a standard basis; (b) to establish the feasibility and performance of a number of design features, including supporting concepts, tile shaping, etc.; (c) to check the capability of NDE techniques to predict defects relevant to the thermal performance of the component. The divertor mockup consists of six half-meter-long armored tubes obtained by brazing CFC to TZM molybdenum alloy. Two types of CFC were used to investigate the advantages of 3-d CFCs with respect to more conventional and cheaper 2-d CFC. The brazing process utilizes three variants of a process developed in laboratory trials and based on selected combinations of active braze filler/CFC surface conditioning procedures. The supporting structure is based on the sliding support concept intended to assure a compromise between the requested thermal stability of the component and the buildup of secondary stresses deriving from mechanical constraints. The FE thermal and thermal mechanical analysis of the divertor mockup structure is reported and the critical areas of sliding support are highlighted for comparison with experimental results. The main results of NDE and experimental high heat flux tests are reported and discussed.