Improvement of hydrogen isotope exchange reactions on Li4SiO4 ceramic pebble by catalytic metals

Abstract Li 4 SiO 4 ceramic pebble is considered as a candidate tritium breeding material of Chinese Helium Cooled Solid Breeder Test Blanket Module (CH HCSB TBM) for the International Thermonuclear Experimental Reactor (ITER). In this paper, Li 4 SiO 4 ceramic pebbles deposited with catalytic metals, including Pt, Pd, Ru and Ir, were prepared by wet impregnation method. The metal particles on Li 4 SiO 4 pebble exhibit a good promotion of hydrogen isotope exchange reactions in H 2 –D 2 O gas system, with conversion equilibrium temperature reduction of 200–300 °C. The out-of-pile tritium release experiments were performed using 1.0 wt% Pt/Li 4 SiO 4 and Li 4 SiO 4 pebbles irradiated in a thermal neutron reactor. The thermal desorption spectroscopy shows that Pt was effective to increase the tritium release rate at lower temperatures, and the ratio of tritium molecule (HT) to tritiated water (HTO) of 1.0 wt% Pt/Li 4 SiO 4 was much more than that of Li 4 SiO 4 , which released mainly as HTO. Thus, catalytic metals deposited on Li 4 SiO 4 pebble may help to accelerate the recovery of bred tritium particularly in low temperature region, and increase the tritium molecule form released from the tritium breeding materials.