THERMOMECHANICAL INVESTIGATION ON DIVERTOR SUPPORTS FOR FUSION EXPERIMENTAL REACTOR - HYDRAULIC EXPERIMENTAL RESULTS

The Japan Atomic Energy Research Institute has been conducting technol ogy development aimed at the construction of a fusion experimental rea ctor to follow JT-60 in Japan. The divertor plate facing the plasma is one of the components of the reactor core assembly, since it has to b e operated under severe heat and particle loads and high electromagnet ic forces. Thus the divertor supports should be designed so as to prov ide both flexibility for thermal expansion along the divertor cooling tube and mechanical stiffness for sustaining the electromagnetic force during plasma disruption as well as easy replacement in the case of f ailure. In order to meet these requirements, we have developed a new d ivertor support system based on a sliding mechanism for flexibility an d a hydraulic cotter for replacement. The basic feasibility of this co ncept has been demonstrated through critical element development. Base d on the feasibility study, a 1:1-scale model of the divertor cooling tube test section with sliding mechanism has been fabricated for therm omechanical experiments to characterize the fluid mechanics, flow-indu ced vibration and flexibility for thermal expansion at various tempera ture profiles during normal and baking operations. Preliminary experim ents on the fluid mechanical characteristics have been conducted as a function of the water velocity and the following results are obtained. (1) The total pressure drop along the whole test section reaches abou t 0.7 MPa at the rated water velocity of 10 m s(-1) at 20 degrees C, w hich is mostly dominated by swirl tape inserts and several bend sectio ns, as expected by design estimation. (2) Flow-induced vibrations are observed at the two overhang bends with smaller curvatures and become significant at a higher water velocity of more than 10 m s(-1).