IN-REACTOR TRITIUM RELEASE EXPERIMENT FROM MOLTEN LITHIUM-LEAD ALLOY (LI17PB83)

An in situ tritium release experiment from molten Li17Pb83 alloy was performed under neutron irradiation at 300-700-degrees-C to investigate the chemical form and release rate of tritium. The dominant chemical form of the released tritium (> 99.9%) from fresh Li17Pb83 was the water-insoluble component (HT, T2), irrespective of the H-2 concentration in He carrier gas (0, 100, 1000, 10000 ppm). After 10 runs, however, the fraction of the water-insoluble component decreased considerably, and depended strongly upon the H-2 concentration in He carrier gas. The tritium release rate was affected by the carrier gas composition and flow mode (sweeping or bubbling). These results suggest that the tritium release is affected by a surface reaction on the molten alloy as well as diffusion and convection in the melt.