Effect of catalytic metals on tritium release from ceramic breeder materials

In most current designs of D–T fusion reactor breeding blankets employing Li-based ceramics as breeder materials, the use of a helium sweep gas containing 0.1% of hydrogen is contemplated to extract tritium via isotopic exchange reactions. However, at temperatures lower than 400 °C, the release process of tritium from the breeders is known to be rather slow. For this reason, there is still a need to develop techniques that promote the release of bred tritium. In order to improve the recovery of tritium from blankets over a wide range of temperature, palladium and nickel were deposited on Li4SiO4 pebbles by the incipient wet impregnation method. Out-of-pile tritium release experiments were conducted using the ceramic breeders irradiated in a research reactor. The experimental results reveal the benefit of the addition of catalytic additive metals, which is effective to increase the tritium release rate from ceramic breeder materials especially at comparatively lower temperatures.