Tritium absorption and desorption in ITER relevant materials: comparative study of tungsten dust and massive samples

Abstract

Tritium adsorption and desorption from well characterized tungsten dust are presented. The dust used are of different types prepared by planetary milling and by aggregation technique in plasma. For the milled powder, the surface specific area (SSA) is 15.5m2/g. The particles are poly-disperse with a maximum size of 200nm for the milled powder and 100nm for the aggregation one. Prior to tritiation the particles are carefully de-oxidized. Both samples are experiencing a high tritium inventory from 5GBq/g to 35GBq/g. From comparison with massive samples and considering that tritium inventory increases with SSA, it is shown that surface effects are predominant in the tritium trapping process. Extrapolation to the ITER environment is undertaken with the help of a Macroscopic Rate Equation model. It is shown that, during the life time of ITER, these particles can exceed rapidly 1GBq/g.