Deuterium behavior at the interface of oxidized metal under high temperature heavy water

Deuterium behavior into the metals soaked in hot heavy water has been investigated in order to understand the oxidation initiated tritium infiltration in the fusion reactor. Disks of SS304, F82H and Ni and gold plated SS304 and F82H as the tritium permeation coating were soaked in an autoclave at 573 K. After the soaking, residual deuterium in the specimen was measured by the thermal desorption method and elemental depth distribution in the specimen was measured by a glow discharge optical elemental spectroscopy method. As the results, the oxide thickness has grown with the soaking time, and infiltrated deuterium amount also increases with oxidation time. Deuterium exists at the interface of the oxide and metals. Deuterium in the gold plated specimens was less than that in the bare SS304 about 1/5. Deuterium in nickel was less than that in the SS304 by one orders magnitude and oxide thickness was also thinner than SS304. Those results indicate that deuterium infiltration into the material would be initiated by the deuterium gas generated at the oxidation process of metal. Gold plating as the permeation reduction coating could be relatively effective to prevent deuterium infiltration into the metal in SS304.