Tritium Retention and Permeation Through Aluminum APT Tubes

Tritium retention in the walls of the He-3 tubes caused by energetic 3He(n,p)3H triton flux is examined by accelerator-based implantation experiments. Retention, measured by post-implantation thermodesorption, is separated into a mobile, permeating and a trapped, near-surface concentration. The mobile fraction is observed to saturate at about 10appm, while the trapped fraction increases linearly with fluence with a retention fraction of 30% until surface blistering occurs. The consequences of this tritium permeation and inventory to APT and potential methods to reduce these quantities are discussed. Published by Elsevier Science Inc.