Speaker
Matthias Kolb
(Institute for Applied Materials)
Description
Advanced ceramic breeder pebbles composed of a mixture of Li4SiO4 (LOS) and Li2TiO3 (LMT) are fabricated and developed at KIT by a melt-based process (KALOS). The produced pebbles are easily characterized for their non-nuclear properties. Yet, as the main properties of a tritium breeder material are the generation and release of tritium, these characteristics also have to be examined.
Neutron irradiation experiments are expensive and require several years of planning, preparation and post irradiation examination in addition to several years of irradiation. Therefore, the comparably rapid development of the breeder pebbles cannot be supported by classical neutron irradiation experiments. Out-of-pile loading of pebbles with tritium can be conducted much more easily and frequently, while providing experimental data of avail in this regard.
Within this work, firstly, the tritium loading of current grades of advanced ceramic breeder pebbles with three different LOS/LMT compositions (20-30 mol% LMT in LOS) and pebbles of EU reference material, was performed in a consistent way. Secondly, the controlled, temperature dependent release of the introduced tritium was investigated by temperature programmed desorption (TPD) experiments to gain insight into the desorption characteristics. As the pebble size can be an influential parameter on the measurements, this factor was addressed by using monosized spheres. The obtained TPD data was decomposed into individual release mechanisms according to well-established desorption kinetics.
The analysis showed that neither the pebble diameter nor the pebble composition of the tested samples severely change the release behavior. Yet, an increased content of lithium metatitanate leads to additional desorption peaks at medium temperatures. The majority of tritium is released by high temperature release mechanisms of chemisorbed tritium, while the release of physisorbed tritium is marginal in comparison. The results allow valuable projections for the tritium release behavior in a fusion blanket.
Co-authors
Matthias Kolb
(Institute for Applied Materials, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany)
Regina Knitter
(Institute for Applied Materials, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany)
Rolf Rolli
(Institute for Applied Materials, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany)
