Tritium retention in plasma facing materials of JET ITER-Like-Wall retrieved from the vacuum vessel in 2012 (ILW1), 2014 (ILW2) and 2016 (ILW3)

Study of Structural and Strength Changes in Lithium-Containing Ceramics-Potential Blanket Materials for Nuclear Power, Subjected to High-Dose Proton Irradiation

The paper considers the hydrogenation processes in Li₂TiO₃ ceramics under irradiation with protons with an energy of 500 keV and fluences of 1 × 10¹⁰-5 × 10¹⁷ ion/cm². The choice of the type of irradiation, as well as the irradiation fluences, is based on the possibilities of modeling hydrogenation processes and studying the kinetics of structural changes caused by the accumulation of radiation damage. The choice of Li₂TiO₃ ceramics as objects of research is due to their prospects for using as blanket materials of thermonuclear reactors for the tritium production and accumulation. It was found that the formation of point defects and their subsequent evolution associated with the formation of complex compounds and the filling of pores, followed by the formation of gas-filled bubbles, the presence of which leads to a decrease in crack resistance and resistance to destruction of the near-surface layer. Based on the data on structural changes and evolution of the crystal lattice parameters, its swelling, a description of the destruction processes associated with hydrogenation in Li₂TiO₃ ceramics was proposed. Also, during the studies, it was found that at irradiation fluences above 1 × 10¹⁷ ion/cm², the appearance of impurity inclusions characteristic of the TiO₂ phase was observed, the presence of which indicates the crystal lattice destruction processes because of accumulation of radiation damage and deformations caused by them. Critical doses are established at which there is a sharp deterioration in strength and crack resistance, reflecting the resistance of ceramics to mechanical external influences.