Draining of a Helium-Cooled Lead Lithium Test Blanket Module by Gravity Under the Influence of a Strong Magnetic Field

A helium-cooled lead lithium blanket has been proposed as a European liquid-metal test blanket module for the experimental campaign in the international thermonuclear experimental reactor ITER. The current design consists of columns of rectangular boxes called breeder units filled with the liquid-metal PbLi. The blanket modules are placed in the region of the strong plasma-confining magnetic field, which causes intense interactions of the flowing liquid metal with induced currents and creates Lorentz forces opposing the flow. Under emergency conditions, the liquid metal has to be removed from the blanket as fast as possible to minimize losses to the surrounding. In case of a leak, the liquid metal has to flow out, driven only by its own weight. This paper analyzes the draining by gravity under the conservative assumption that the magnetic field is not switched off. The geometric elements creating the major magnetohydrodynamics resistance to the draining fluid are identified to support further improvements in the design.