Liquid metal magnetohydrodynamic flows in manifolds of dual coolant lead lithium blankets

•MHD flows in model geometries of DCLL blanket manifolds.•Study of velocity, pressure distributions and flow partitioning in parallel ducts.•Flow partitioning affected by 3D MHD pressure drop and velocity distribution in the expanding zone.•Reduced pressure drop in a continuous expansion compared to a sudden expansion.

An attractive blanket concept for a fusion reactor is the dual coolant lead lithium (DCLL) blanket where reduced activation steel is used as structural material and a lead lithium alloy serves both to produce tritium and to remove the heat in the breeder zone. Helium is employed to cool the first wall and the blanket structure.Some critical issues for the feasibility of this blanket concept are related to complex induced electric currents and 3D magnetohydrodynamic (MHD) phenomena that occur in distributing and collecting liquid metal manifolds. They can result in large pressure drop and undesirable flow imbalance in parallel poloidal ducts forming blanket modules.In the present paper liquid metal MHD flows are studied for different design options of a DCLL blanket manifold with the aim of identifying possible sources of flow imbalance and to predict velocity and pressure distributions.