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

Nakamura, Hirofumi; Hatano, Yuji*; Yamanishi, Toshihiko

Deuterium behavior in the metal exposed to hot heavy water has been investigated in order to understand the oxidation driven tritium permeation in the fusion reactor. Disks of SS304, F82H and Ni and gold plated SS304 and F82H were oxidized in an autoclave at 573K. After the oxidation, soaked 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. Obtained results were followings, (1) The oxide thickness has grown with the soaking time, and solved deuterium amount also increases with oxidation time for all materials. (2) Deuterium exists at the interface of the oxide and metal for all materials. (3) Deuterium in the gold plated samples were less than that in the bare SS304 about 1/5. (4) 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 solution into the material would be initiated by the deuterium gas production at the oxidation process of metal. Gold plating as the oxidation protection could be effective to prevent deuterium solution into the metal.