Tritium retention and migration in beryllium

With the recent successful operation in JET, beryllium must be considered a leading plasma-facing material. However, little is known about beryllium's hydrogen isotope retention and migration properties. This paper presents the results of a coordinated experimental program performed o characterize the hydrogen isotope retention and release in beryllium. In the first set of experiments, measurements of the plasma-driven permetation of deuterium through beryllium membranes were conducted. No detectable permeation was obtained for temperatures below 670 K, and the higher temperature results wer strongly affected by the oxide layers on the samples. In the second set of experiments, samples were exposed to a D-T plasma in the Tritium Plasma Experiment. The samples were subsequently removed for dissolution tritium counting. The retention was seen to initially decreasing with exposure temperature, but reached a local maximum at 770 K. (orig.)D