Tritium permeation, retention and release properties of beryllium pebbles

Beryllium pebbles of 1 mm diameter produced by Rotating Electrode Method (REM) were exposed to thermodesorption tests after preliminary loading of hydrogen/tritium gas mixture in the temperature range between 973 and 1373 K for 1-12 h. The aim of the work is to clarify the application of the used loading method for modeling of neutron irradiation from the point of view of tritium loading into beryllium samples with bulk uniformity. The formation of surface beryllium oxide layer on pebbles during the loading leads to limitation of tritium/hydrogen permeation into the loaded beryllium pebbles. The thickness of the oxide layers increases with the growth of loading temperature at the investigated temperature area. The optimal loading temperature for beryllium pebbles is supposed to be not higher than 973 K.