1. Japan Nuclear Fuel Ltd., Safety Technology Office, Obuchi, Rokkasho-mura Aomori 039-3212, Japan
2. NPO Institute of Science and Technology for Society, Irifune 3-49-102 Urayasu, Chiba 279-0012, Japan
3. The University of Tokyo, School of Engineering, Department of Nuclear Engineering and Management, 7-3-1 Hongo, Bunkyoku, Tokyo 113-8656, Japan