Two Different Medium-Scale First Wall Fabrication Experiments at KIT for ITER Helium-Cooled Pebble Bed Test Blanket Module

Subcomponent manufacturing and assembly concepts for the fabrication of the helium-cooled pebble bed test blanket module (TBM) for ITER have been developed over more than one decade at KIT, in particular the first wall (FW), which is a key element for the TBM fabrication. The design of this subcomponent foresees the manufacturing of a large U-bended plate of EUROFER with built-in channels for helium cooling. Manufacturing technologies developed at KIT are based on diffusion welding of two half-plates as the most promising option. This paper deals with the manufacturing of two medium-scale TBM FW mock ups according to two different industrial processes: a uni-axial diffusion welding process realized in a mechanic press at high temperature and a hot isostatic pressing process applied to a canned assembly at relatively low pressure.

The qualification of the welds produced is described, and the results are compared to previous small- and medium-size scale experiments. The results of the recent FW fabrication mock ups are presented with regard to material data (e.g., ultimate strength, ductile-brittle transition temperature) and TBM-relevant parameters (e.g., deformation of cooling channels). The paper concludes with an overview of the strategy to evolve from 1/8th-scale experiments to TBM-relevant dimensions.