1. Nuclear Power R&D Center; Tokyo Electric Power Company, 4-1 Egasaki, Tsurumi, Yokohama, 230-8510, Japan
2. Power and Industrial Systems R&D Laboratory, Hitachi, Ltd., 7-2-1 Omika, Hitachi, Ibaraki, 319-1221, Japan
3. Nuclear Systems Division, Hitachi, Ltd., 3-1-1 Saiwai, Hitachi, Ibaraki, 317-8511, Japan