1. Faculty of Education and Integrated Arts and Sciences; Waseda University; Shinjuku-ku; Tokyo; 169-8050; Japan
2. Department of Earth Sciences; Resources and Environmental Engineering; Graduate School of Creative Science and Engineering; Waseda University; Shinjuku-ku; Tokyo; 169-8050; Japan
3. Research Institute of Science and Engineering; Waseda University; Shinjuku-ku; Tokyo; 169-8050; Japan
4. Kyoto Fission-Track Co. Ltd; Kita-ku; Kyoto; 603-8832; Japan