1. Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors Oh-okayama, Meguro-ku, Tokyo 152, Japan
2. Japan Atomic Energy Research Institute, Tokai Establishment, Tokai-mura, Ibaraki-ken 319-11, Japan
3. NAIG Nuclear Research Laboratory, Nippon Atomic Industry Group Company, Ltd., Ukishima-choy Kawasaki-ku, Kawasaki 210, Japan