1. a Faculty of engineering, Himeji Institute of Technology , Shosha Himeji, 671-22, JAPAN
2. b Oarai Engineering Center, Power Reactor and Nuclear Fuel Development Corporation , Oarai, Higashi-Ibaraki, Ibaraki, 311-13, JAPAN
3. c Government Industrial Research Institute Osaka , Ikeda, Osaka, 563, JAPAN