Tritium release performance of biphasic Li2TiO3–Li4SiO4 ceramic pebbles fabricated by centrifugal granulation method

Abstract

At present, the biphasic Li2TiO3–Li4SiO4 ceramic pebbles with high lithium content and crushing load have been viewed as promising tritium breeders for maintaining the safety-state operation of the D-T fusion reactor. The tritium release behavior of Li2TiO3–Li4SiO4 ceramic pebbles fabricated by centrifugal granulation method was investigated by using the Thermal Desorption Spectroscopy apparatus at Shizuoka University. It can be found that the Li2TiO3–Li4SiO4 ceramic pebbles show three tritium release peaks, and most of the tritium was released as HTO observed from T-TDS spectra, and the peaks at 581 K and 734 K are mainly due to tritium release from Li2TiO3 in core and shell. The peak at 813 K is mainly deemed as tritium release derived from the Li4SiO4 shell. The content of tritium release from biphasic Li2TiO3–Li4SiO4 ceramic is up to 11.5 MBq g−1, but the amount of gas species (HT) is only 0.126 MBq g−1. Besides, the isothermal heating experiment showed that the tritium release behavior was subject to diffusion process and de-trapping in defect sites. At the same time, the irradiation defects of E′-center, O-related center, and Ti3+ for breeding material can be found by using an ESR device, and the isochronous heating experiments have manifested that the amount of irradiated defect decreases as heating temperature increases, which indicates that the tritium release behavior is closely related to defect annihilation process. Therefore, the advanced Li2TiO3–Li4SiO4 ceramic breeder can be fabricated based on tritium release result, which will be conducive to meet the practical application of breeder in the future.