Abstract
Plasma facing components for energy conversion in future nuclear fusion reactors require a broad variety of different fabrication processes. We present, along a series of studies, the general effects and the mutual impact of these processes on the properties of the EUROFER97 steel. We also consider robust fabrication routes, which fit the demands for industrial environments. This includes heat treatment, fusion welding, machining, and solid-state bonding. Introducing and following a new design strategy, we apply the results to the fabrication of a first-wall mock-up, using the same production steps and processes as for real components. Finally, we perform high heat flux tests in the Helium Loop Karlsruhe, applying a few hundred short pulses, in which the maximum operating temperature of 550 °C for EUROFER97 is finally exceeded by 100 K. Microstructure analyses do not reveal critical defects or recognizable damage. A distinct ferrite zone at the EUROFER/ODS steel interface is detected. The main conclusions are that future breeding blankets can be successfully fabricated by available industrial processes. The use of ODS steel could make a decisive difference in the performance of breeding blankets, and the first wall should be completely fabricated from ODS steel or plated by an ODS carbon steel.
Highlights
In 2014 the EU started a Pre-Conceptual Design phase to explore and define the technical options for the European demonstration fusion power plant (DEMO)
Another novelty of this study is the cyclic high heat flux test in a helium cooling loop, in which the surface temperature of a first wall mock-up could be intentionally increased above 550 ◦ C, which is the common operating limit of the nuclear fusion steel EUROFER97
This study clearly demonstrates that base material ductility of TIG welds will only be restored by tempering temperatures of at least 740 ◦ C or higher
Summary
In 2014 the EU started a Pre-Conceptual Design phase to explore and define the technical options for the European demonstration fusion power plant (DEMO). After a revision of the European Fusion R&D program and strategy, the focus is on the two most promising concepts, namely, the Helium-Cooled Pebble Bed (HCPB) and Water-Cooled Lithium Lead (WCLL) blankets. These blankets form a torus shaped surface towards the plasma, the first wall (FW), which in turn covers about 1000 m2. The number of single blanket boxes that form the blanket is in the order of 1000 pieces. The International Thermonuclear Experimental Reactor (ITER)—currently under construction in Southern France—will be equipped with testing ports for such blanket boxes. Within a Test Blanket Modul (TBM) program, specific HCPB and WCLL prototype blanket boxes will be tested. A general overview, as well as details, can be found in [1,2,3,4,5,6] and references therein
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