1. Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency, 4002 Narita-cho, Oarai-machi, Ibaraki 311-1393, Japan
2. Oarai Research and Development Institute, Japan Atomic Energy Agency, 4002 Narita-cho, Oarai-machi, Ibaraki 311-1393, Japan
3. Institute for Materials Research, Tohoku University, 2145-2, Narita-cho, Oarai-machi, Higashiibaraki-gun, Ibaraki 311-1313, Japan
4. Department of Nuclear Technology, Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka, Niigata 940-2188, Japan