1. Energy and Environmental Systems Laboratory, Hitachi, Ltd., 7-2-1 Omika-cho, Hitachi-shi, Ibaraki 319-1221, Japan
2. Hitachi-GE Nuclear Energy, Ltd., 1-1 Saiwai-cho 3-chome, Hitachi-shi, Ibaraki 317-0073, Japan
3. Japan Atomic Power Company, 1-1 Kanda-Mitoshiro-cho, Chiyoda-ku, Tokyo 101-0053, Japan