1. Japan Atomic Energy Research Institute, Department of Nuclear Reactor Engineering Tokai, Ibaraki, 319-11, Japan
2. Tohoku University, Cyclotron and Radioisotope Center, Aramaki, Aoba-ku, Sendai 980, Japan
3. Kyoto University, Department of Nuclear Engineering, Yoshida, Sakyo-ku, Kyoto 606, Japan
4. Japan Atomic Energy Research Institute, Takasaki Establishment Watanuki-cho, Takasaki, 371-12, Japan
5. Tohoku University, Department of Nuclear Engineering, Aramaki, Aoba-ku, Sendai 980, Japan