1. Departement of Nuclear Technology, Nagaoka University of Technology, Nagaoka, Niigata, Japan
2. Oarai Research and Development Institute, Japan Atomic Energy Agency, Oarai-Machi, Higashi-Ibaraki-Gun, Japan
3. International Research Center for Nuclear Science, Institute for Materials Research, Tohoku University, Oarai-Machi, Higashi-Ibaraki-Gun, Japan