Reduction of MHD pressure drop by electrical insulating oxide layers in liquid breeder blanket of fusion reactors

The electrical conductivity of the α-Al2O3 layer formed on FeCrAl alloy APMT (Fe-21Cr-5Al-3Mo) in air atmosphere at 1273 K and 1373 K was measured in a temperature range between room temperature and 1073 K. Low electrical conductivity of the α-Al2O3 layer was clarified in the measurement temperature range. Low electrical conductivity of the ZrO2 layer formed on the Zr metal in air atmosphere at 873 K was also measured. Numerical simulation was performed with three-dimensional thermo-fluid code to clarify the reduction of magnetohydrodynamic (MHD) pressure drop with the electrical insulating α-Al2O3 and ZrO2 layers in liquid blankets of magnetic confinement fusion reactors. The MHD pressure drop is significantly reduced when the four inner surfaces of the duct are electrically insulated by the oxide layers. The electrical insulation of the three inner surfaces is also effective to reduce the MHD pressure drop when the magnetic field is parallel to the conductive wall of the flow duct. However, the MHD pressure drop is induced in the three-surface insulation duct when the magnetic field makes an angle with the conductive wall of the duct.