Hydrogen permeation from F82H wall of ceramic breeder pebble bed: The effect of surface corrosion. (29th January 2022) - Mukai, Keisuke
Abstract: Understanding the permeation behavior of tritium from a pebble bed breeding blanket is essential for establishing a self-sufficient fuel cycle in a nuclear fusion reactor. It is known that double corrosion layers forms on reduced activation ferritic-martensitic (RAFM) steel surface by gas release from a ceramic breeder material, however, its effect on hydrogen permeation behavior has not been elucidated. Herein, in-situ measurement of hydrogen permeation through an F82H RAFM wall of a ceramic breeder pebble bed was performed under H2 -added sweep gas conditions. The corrosion layer formed on the F82H sample had a dense microstructure, which reduced hydrogen permeation flux at least by one order of magnitude. The permeation reduction factors were 20–50 at the water-coolant temperature of a blanket. A self-repairing ability is expected for the surface oxide layer as the corrosion occurs spontaneously inside a breeding blanket. Graphical abstract: Image 1 Highlights: In-situ hydrogen permeation test from F82H wall of LTZO ceramic breeder pebble bed. Surface corrosion oxide layers on RAFM F82H steel reduced hydrogen permeation. The corrosion layer achieved permeation reduction factors of 20–50 at 598 K. The activation energies of hydrogen permeation were 0.65–0.78 eV. The layers showed a thermal stability with a possible self-repairing ability.