Tritium release from neutron-irradiated Li2O sintered pellets: fluence dependence

The tritium release curves from the lower density region (71-86% TD) sintered pellets which were irradiated by thermal neutrons up to the fluences of 4x1020, 2x1021, 2x1022 and 2x1023 n/m2 have one peak around 570, 590, 610 and 620 K, respectively. It means that no dependence on porosity is observed for these densities and fluences. This suggests that the tritium generated by thermal neutron irradiation is trapped in the irradiation defects introduced by irradiation of the bulk. The curves from the intermediate density region (87-89% TD) pellets which were irradiated up to same fluences as the lower also have one peak around 620, 640, 660 and 680 K, respectively. This means that the peaks tend to shift to higher temperatures by thermal neutron fluence, much the same as the 71-86% TD pellets. The curves from the higher density region (90-92.5% TD) pellets irradiated up to 4x1020 n/m2 have plural peaks. The curves from the pellets irradiated up to 2x1021, 2x1022 and 2x1023 n/m2 also have the same number of peaks, and a dependence of the temperatures of the peaks on the fluences is not observed