Release of tritium from boron carbide

The release of tritium from B4C powder and a single crystal has been investigated in the temperature range 400-8000C. High-energy tritons, produced by bombarding a Cu target with 104 MeV α-particles, were used to prepare samples with a uniform tritium distribution. The release curves were analysed under the assumptions that (a) the diffusion within the B4C is the rate-controlling step and (b) the effective average grain size can be deduced from the specific surface area of the powder. The release of tritium from sintered material, with densities of 70-95% of the theoretical density, as well as from preoxidized samples has also been investigated. The diffusion coefficient DB2O3 for tritium in B2O3 is more than two orders of magnitude smaller than D(B4C). (author)