Speaker
Description
Liquid metals such as lead lithium (PbLi) are foreseen in future fusion reactors as coolant, heat transfer medium, and breeder material for generation of tritium, one of the plasma fuel components. The motion of an electrically conducting fluid in the plasma-confining magnetic field gives rise to induced currents and electromagnetic forces that significantly alter the flow behavior compared to hydrodynamic conditions. In the Water-Cooled Lead-Lithium (WCLL) blanket concept, PbLi circulates slowly for tritium removal, while the heat is extracted at cooling pipes immersed in the breeding zone. The liquid metal is distributed and collected among a large number of breeder units by manifolds, and it is expected that those electrically coupled complex components cause the major fraction of magnetohydrodynamic (MHD) pressure drop.
A scaled mock-up of the WCLL test blanket module to be tested in the International Thermonuclear Experimental Reactor (ITER) has been designed and manufactured at KIT. Experiments using NaK as surrogate fluid have been performed in the MEKKA laboratory. Flows investigated for various Reynolds numbers Re and for different Hartmann numbers up to Ha=4000 reveal highest pressure drop contributions in manifolds and, for the present ITER design, an inhomogeneous flow distribution among breeder units that is unfavorable for tritium extraction. Recommendations are made for future design improvement to resolve this issue.
Acknowledgment: This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No 101052200 — EUROfusion). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them.
