1. Department of Mechanical and Control Engineering , Kyushu Institute of Technology , 1-1 Sensui-cho, Tobata-ku, Kitakyushu, Fukuoka, 804-8550 Japan
2. Department of Mechanical Engineering , Aoyama Gakuin University , 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258 Japan
3. Safety Department, Safety and Quality Division, Japan Nuclear Fuel Limited , 4-108 Okitsuke, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori, 039-3212 Japan