Intense Correlationship Proved Between Irradiation Damage and Performances of Tritium Breeding Materials

Severe irradiation environment would bring damage to the microstructure of the materials and affect the stable operation and tritium recovery of fusion reactor. Therefore, the efficient tritium production from tritium breeding materials is the guarantee for the realization of tritium self-sufficiency in fusion reactor.

A research group who have been focusing on tritium breeding materials for years conducted a series of study on the mechanism of irradiation-induced change of microstructure and the effects on mechanical, tritium release, and thermal performances in solid tritium breeding materials, which provided a reference method for evaluating the material’s irradiation stability, and guidance for material optimization.

The team is led by QI Qiang from the Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, and the latest results have been published in Nuclear Fusion.

In this research, the research group adopted 2MeV helium ion to irradiate Li₂TiO₃, a kind of tritium breeding material. The changes of microstructure and mechanical performance were investigated by multi-path characterization. The correlation between the type of damage and nanoindentation hardness was established based on the hardness theory, clarifying the mechanism of irradiation damage acting on mechanical performance.

The systematical studies on tritium release performances from candidate and advanced tritium breeding materials, which are preferred by Chinese Fusion Engineering Testing Reactor (CFETR), provided suggestions for the selection of tritium breeding materials. In the study conducted earlier this year, the team investigated its tritium release behavior. The characteristic parameters of tritium release and retention revealed the key effects of tritium release.

As for preservation of future hundreds of tons’ tritium breeding materials employed in fusion reactor, they also gave recommendations. Corresponding thermal data were obtained in the thermal performance study under irradiation and long-term high temperature service conditions, which provided support for the design of the blanket in fusion reactor.

The team's research involves the effect of irradiation on thermal and mechanical performances, tritium release behavior from neutron-irradiated tritium breeders, stability of long-term high-temperature service. They provided reference for the design of fusion reactor blanket and optimization of tritium breeder materials.

Fig. 1 Raman spectra of different regions of Li2TiO3 irradiated by He ions (Image by GU shouxi/QI Qiang)

Fig. 2 Tritium release spectra of neutron-irradiated tritium breeding materials (Image by GU shouxi/QI Qiang)