The Fabrication of a Vanadium-Stainless Steel Test Section for MHD Testing of Insulator Coatings in Flowing Lithium

To test the magnetohydrodynamic (MHD) pressure drop reduction performance of candidate insulator. coatings for the ITER Vanadium/Lithium Breeding Blanket, a test section comprised of a V-4Cr-4Ti liner inside a stainless steel pipe was designed and fabricated. Theoretically, the MHD pressure drop reduction benefit resulting from an electrically insulating coating on a vanadium-lined pipe is identical to the benefit derived from an insulated pipe fabricated of vanadium alone. A duplex test section design consisting of a V alloy liner encased in a SS pressure boundary provided protection for vanadium from atmospheric contamination during operation at high temperature and obviated any potential problems with vanadium welding while also minimizing the amount of V alloy material required.

From the MHD and insulator coating point of view, the test section outer SS wall and inner V alloy liner can be modeled simply as a wall having a sandwich construction.

Two 52.3 mm OD × 2.9 m long V-alloy tubes were fabricated by Century Tubes from 64 mm × 200 mm × 1245 mm extrusions produced by Teledyne Wah Chang. The test section's duplex structure was subsequently fabricated at Century Tubes by drawing down a SS pipe (2 inch schedule 10) over one of the 53.2 mm diameter V tubes.