Influence of various gases and water vapors on the processes of tritium release from two-phase lithium ceramics

The processes of tritium generation and release in lithium-ceramic breeder blankets are affected by many factors, for example, the presence of impurities in the purge gas. As was shown earlier, oxygen, water vapor and hydrogen have the greatest influence on gas release from lithium ceramics. Hydrogen is planned to be specifically added to the purge gas mixture in breeder blanket to facilitate tritium release. The paper presents data of reactor experiments on irradiation of two-phase lithium ceramics (65 mol% Li4SiO4 /35 mol% Li2TiO3) under conditions of supplying various gases and water vapor into the chamber with samples. We analyzed the sections of experiments in which sequential, step-by-step injection of water, oxygen, hydrogen and deuterium vapors into a continuously pumped chamber with samples at steady-state quasi-equilibrium release of tritium from ceramics was carried out. Using a mass spectrometer, the gas composition in the chamber and, in particular, the release features of tritium-containing molecules, were recorded. Based on the obtained data, the mechanisms of tritium interaction with the investigated gases and water vapor on the ceramic surface were determined, as well as their influence on the processes of tritium release from ceramics.