Abstract
Because of large capacity of hydrogen occlusion in graphite, both hydrogen recycling and tritium retention are key issues for future utilization of graphite. Below 500K, where hydrogen does not seem to diffuse in, saturated level of hydrogen in graphite exposed to plasma is as high as 0.4 in H/C ratio. Above 500K hydrogen behavior in graphite becomes very complex and no adequate model has established yet. In the present paper, current knowlege of hydrogen behavior in graphite has been summarized and some ideas for understanding hydrogen recycling and suggestions for future work are given.
