Chemical compatibility of bulk alumina in flowing PbLi alloy under magnetic field

Electrically insulating flow channel inserts (FCI) may be needed in liquid-based breeding blanket concepts to electrically decouple the metal flow from the strong magnetic field in a future fusion reactor. Although the magnetohydrodynamic simulation demonstrates a reduction of the pressure drop when a sandwich-like steel-alumina-steel FCI is employed, the tritium production efficiency in the breeding zone of a breeding blanket is limited to 550 °C due to the steel corrosion. Previous theoretical thermomechanical analyses point out the possible occurrence of induced interfacial stresses between the steel and the ceramic part. Both factors motivate the actual FCI development towards the avoidance of the steel protection. Therefore, a chemical compatibility study between high density alumina and hot PbLi was addressed during this experimental work by using the Energy Dispersive X-ray spectroscopy elemental analysis coupled to a scanning electron microscope. Analyzed samples were previously tested during 1000 hs in an experimental PbLi loop at 550 °C affected by a 1.35 T magnetic field. Results allow concluding the high confidence to expose the insulator directly to the liquid flow.