Development of a direct insulation layer for a self-cooled liquid metal fusion reactor blanket

The magneto-hydrodynamic (MHD) pressure drop in a self-cooled liquid metal fusion reactor blanket can be significantly reduced by means of electrical insulation of the flowing liquid metal against the structural material. Since alumina is chemically stable against Pb-17Li at up to 500°C, direct insulation of MANET steel was performed by aluminizing the steel, using a hot-dip process followed by high-temperature oxidation. The aluminide layer formed in this process was insulating and stable against corrosion in flowing Pb-17Li alloy at 450°C for 10 000 h. Several temperature changes during the corrosion tests did not cause any damage of the insulating layers. Thus, the process of hot-dip aluminizing followed by optimized oxidation at high temperature can provide a direct insulation layer to suppress MHD effects.