Temperature-programmed desorption of tritium loaded into beryllium

The influence of grain size and amount of beryllium oxide BeO on the tritium release characteristics of the S-65H and I-220H beryllium grades was investigated. The beryllium samples were loaded with hydrogen at a temperature of 1123 K for 6 h at a pressure of 4 bar in a gas mixture of molecular protium with 45 wppm tritium. The tritium release measurements were performed using a stepped heating ramp with steps of 50 K in the temperature range of 473-1373 K with a duration of each step of 1 h. Five major release peaks were observed. Interpretations of the nature of the peaks are suggested. In particular, we ascribe the low-temperature peaks (300-723 K) to desorption from the surface and connect the shift of the peak at elevated temperature (900-1000 K) with the enhanced diffusion of hydrogen along grain boundaries. The high temperature peak (1123-1373 K) is attributed to dissociation of beryllium hydroxide Be(OH)2, which is formed on the surface and grain boundaries of a sample in a reaction of hydrogen isotopes with beryllium oxide.