1. Department of Energy Technology, Research Institute, Ishikawajima-Harima Heavy Industries Co., Ltd., Isogo-ku, Yokohama 235, Japan
2. Department of Chemical Engineering, Kyushu University, Higashi-ku, Fukuoka 812, Japan
3. Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki-ken 319-11, Japan