Buoyant-MHD Flows in HCLL Blankets Caused by Spatially Varying Thermal Loads

In the helium-cooled lead lithium (HCLL) blanket concept convective phenomena caused by nonuniform thermal conditions due to bulk neutron volumetric heating can occur. Buoyancy can become very important and modify the velocity distribution and related heat transfer performance of the blanket. A numerical study has been performed to investigate liquid metal flows driven by buoyant forces in a breeder unit (BU) of a HCLL test blanket module (TBM) under the influence of intense uniform magnetic fields. According to the last design review, two internal cooling plates subdivide the fluid domain into three slender flow regions, which are thermally and electrically coupled through common walls. First, a uniform volumetric heat source is considered to identify the basic convective patterns that establish in the liquid metal. Results are then compared with those obtained by applying a realistic radial distribution of the power density as obtained from a neutronic analysis. This paper summarizes the main effects of spatial gradients of a neutron thermal load on velocity and temperature distribution in magnetohydrodynamic flows in a BU of a HCLL TBM.