Determination of Maximum Permissible Defects during Brazing of Tungsten–Copper Armor Tiles for ITER Divertor Dome Plasma Facing Units

The divertor is the most heat-loaded component of a fusion reactor. Its plasma facing units (PFUs) are subjected to extreme thermal, ion, and neutron loads. These elements are technically complex and very expensive to manufacture. Therefore, when certain defects occur during series production of the PFUs, it is important to determine whether such unit is to be rejected or whether the detected defect is not critical and will not affect the PFU performance under the specified conditions of its operation in the reactor. This article presents an experimental study of the influence of the brazing defects of tungsten armor tiles to the water-cooled heat sinks of the divertor dome (DD) PFUs for the International Thermonuclear Experimental Reactor (ITER) on the performance of these units. The defects of different shape, size, and localization are considered in the interface between the tungsten armor and bronze substrate of the PFU. The permissible sizes of such defects are specified at which the PFU successfully passes acceptance tests and can be used in the reactor.