1. Japan Atomic Energy Research Institute, Tritium Engineering Laboratory Department of Fusion Engineering Research, Shirakata Shirane 2-4 Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan
2. Los Alamos National Laboratory, Energy Science and Application Tritium Science and Engineering, P.O. Box 1663, Los Alamos, New Mexico 87545