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Home / Publications / Journals / Fusion Science and Technology / Volume 54 / Number 2

Influence of Oxygen on Permeation of Hydrogen Isotopes Through Group 5 Metals

Yuji Hatano, Andrei Busnyuk, Vasily Alimov, Alexander Livshits, Yukio Nakamura, Masao Matsuyama

Fusion Science and Technology / Volume 54 / Number 2 / August 2008 / Pages 526-529

Technical Paper / Materials Interactions

Group 5 metals (V, Nb and Ta) are potential candidates of tube material in vacuum permeator for tritium recovery from Pb-17Li liquid blanket system. From this viewpoint, the influence of oxygen on the surface reaction rates of hydrogen on V and Ta were examined in an ultra-high vacuum apparatuses at elevated temperatures, and the results were compared with the data on Nb acquired in a previous study. The surface reaction rates of hydrogen on V and Ta, and consequently permeation rates, decreased with increasing oxygen concentration in the bulk as previously observed for Nb. These observations were ascribed to the increase in surface oxygen coverage with increasing bulk oxygen concentration. The weakest influence of oxygen on hydrogen permeation rate was observed for V. The expected permeation rate through V under typical blanket conditions, however, was not necessarily high due to high oxygen solubility in V. The evaluation indicated that the highest permeation rate should be obtained with Nb under typical blanket conditions.

 
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