Experimental Study on Mechanical Characteristics of Li₂TiO₃ Pebble Beds Under Cyclic Loading

The lithium titanate (Li₂TiO₃) ceramic pebble bed is one of the main tritium breeder candidates in the solid blankets of fusion reactors. Under the extreme operating conditions of fusion blankets, such as neutron irradiation, high temperatures, structural material extrusion, and stress concentration, the mechanical characteristics of tritium breeding pebble beds not only affect the mechanical performance of the blanket but also affect tritium production and extraction. Therefore, an experimental apparatus was built to characterize the mechanical behavior of 0.47 and 0.99 mm Li₂TiO₃ pebble beds. A uniaxial compression test was performed under the cyclic mechanical loads of 4, 6, and 8 MPa, respectively. It was shown that large irreversible residual strain appeared in the Li₂TiO₃ pebble bed with the increase of loading cycles and that the mechanical characteristics of the pebble beds were greatly affected by different mechanical loads and particle sizes. The current results provide relevant experimental data that can support the design of fusion blankets.