High heat flux performance of neutron irradiated plasma facing components

Abstract

During the operation of ITER, the plasma facing components will undergo different kinds of thermal loadings like thermal fatigue, vertical displacement events and disruptions. In addition degradation effects due to neutron irradiations may play an important role. The electron beam facilities JUDITH and OHBIS have been designed to carry out ITER relevant simulation experiments on neutron irradiated materials and components. Carbon fiber reinforced carbon materials (CFC), Be and W alloys have been tested in thermal shock experiments. Thermal fatigue experiments have been performed with joints of these materials to Cu alloys. In thermal fatigue experiments no influence on the quality of the joints was observed whatever the testing facilities or materials combinations. But for CFC mock-ups the surface temperature is significantly increased due to the reduction in thermal conductivity. During experiments at high power densities annealing effects could be observed. Thermal shock tests show a higher erosion after neutron irradiation. The tests described above are not able to simulate the superposition of nuclear and thermal loads. In order to study the synergistic effects, in-pile thermal fatigue experiments with two CFC/Cu mock-ups and a Be–Cu mock-up have been performed in the SM-2 fission reactor in Dimitrovgrad (Russia). A first evaluation showed good performance of all three mock-ups.