1. Japan Atomic Energy Agency 801-1 Mukouyama, Naka, Ibaraki 311-0193, Japan
2. Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8550, Japan
3. National Institute for Fusion Science 322-6 Oroshi-cho, Toki, Gifu 509-5292, Japan
4. Kyoto University, Institute of Advanced Energy Gokasho, Uji, Kyoto 611-0011, Japan