Exchange of tritium implanted into oxide ceramics for protium by exposure to air vapors at room temperature

The exchange of tritium, implanted into an oxide ceramic with a pure tritium ion beam, for protium by exposure to normal air at room temperature has been measured in a collaboration experiment with the Tritium Laboratory group, JAERI. It is shown that the release of THO produced by the exchange H2O+T→THO+H at the surface of the crystallites decreases monotonically with exposure time, while the release of TH gas increases in the beginning, reaches a maximum and decreases monotonically as the time increases. The latter behavior of TH gas release gives an important evidence for bulk recombination of H uptaken from the surface with T implanted. These results are discussed based on the one-way diffusion model proposed previously for the explanation of the D–H exchange experiment.