Speaker
Description
Oliver Leysa, Julia Leysa, Regina Knittera
a. Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM), Karlsruhe, Germany
Abstract: The KALOS process is used at the Karlsruhe Institute of Technology for the production of Advanced Ceramic Breeder (ACB) pebbles. These pebbles, composed of lithium orthosilicate with a strengthening phase of lithium metatitanate, are regarded as the EU reference solid breeding material and will be featured in the ITER HCCP, as well as DEMO blankets. The melt-based process involves heating synthesis powders in a platinum alloy crucible inside a furnace to form a melt. Pressure is applied to the crucible to force the melt through a small nozzle, thereby forming a laminar jet, which breaks up into droplets that are then solidified in a cooling tower to form pebbles. After production, a comprehensive standardised characterisation is performed on each batch.
In order to provide the roughly 90 kg of ACB pebbles that will be required for an ITER test blanket module, the process recently underwent a significant upgrade, where the main goal was to increase the capacity of the process, while maintaining the high quality of the pebbles. In the past, the maximum batch size was limited by the volume of the melting crucible, which in turn was limited by the useable space inside the process furnace. To address this problem, the process has been converted from a batch operation to a process where the synthesis powders can be continuously fed into the melting crucible. The changes have resulted in a theoretical maximum production capacity of 10 kg in a working day.
This work will look at the first production results for the first batches produced using the new process set-up. This includes an examination of various aspects of the process stability and reliability, including critical variables such as the process pressure or temperatures at the nozzle and in the cooling tower. The characterisation of the pebbles focuses on the main pebble properties, including the pebble sizes and distribution, the mechanical strength, the porosity, as well as an analysis of the phases and chemistry.
The findings confirm the reliability and consistency of the upgraded process, as well as the high quality of the produced pebbles. This shows that not only will the KALOS process be able to produce the pebbles required for testing in ITER, but that it also demonstrates that it is possible to upscale the technology to an industrial scale.
