1. Hitachi, Ltd., Hitachi Research Laboratory 7-2-1 Omika-cho, Hitachi-shi, Ibaraki 319-1221, Japan
2. Hitachi-GE Nuclear Energy, Ltd. Hitachi Works, 3-1-1 Saiwai-cho, Hitachi-shi, Ibaraki 317-0073, Japan
3. Tohoku University, School of Engineering Department of Quantum Science and Energy Engineering 6-6-01-2 Aoba-ku, Sendai-shi, Miyagi 980-8579, Japan