Isotope exchange reaction on solid breeder materials

Lithium ceramic materials such as Li2O, LiAlO2, Li2ZrO3, Li2TiO3 and Li4SiO4 are considered to be as candidate for the tritium breeding material in a deuterium–tritium (D–T) fusion reactor. In the recent blanket designs, helium gas with hydrogen or deuterium is planned to be used as the blanket purge gas to reduce tritium inventory and promote tritium release from the breeding material. In addition, the rate of isotope exchange reaction between hydrogen isotopes in the purge gas and tritium on the surface of the breeding material is necessary to analyze the tritium release behavior from the breeding materials. However, the rate of isotope exchange reactions between hydrogen isotopes in the purge gas and tritium on the surface of those materials has not been quantified until recently. Recently, the present authors quantified the rate of isotope exchange reaction on Li2O and Li2ZrO3. The overall mass transfer coefficients representing the isotope exchange reaction between H2 and D2O on breeding materials or the same between D2 and H2O are experimentally obtained in this study. Comparison to isotope exchange reaction rates on various breeding materials is also performed in this study. Discussions about the effects of temperature, concentration of hydrogen in the purge gas or flow rate of the purge gas on the conversion of tritiated water to tritium gas are also performed.