Plasma and Fusion Research
Volume 17, 2405096 (2022)
Regular Articles
- Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
- 1)
- National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
Abstract
Neutrons are generated in a fusion plasma and induce various radionuclides via a nuclear reaction with fusion reactor materials. Evaluating the kinds of nuclide and the amount of induced radioactivity is important for decommissioning planning and regular maintenance. In this study, we verified a long-term prediction model of induced radioactivity in the large helical device (LHD) model by comparing induced radioactivity generated during deuterium plasma experiments in LHD with results calculated using a high-energy particle-induced radioactivity code. The metals employed for activation were SUS316L, Co, Mo, and Ni. During the deuterium plasma experiments, these materials were placed on an 8-O port of the LHD, and the induced radioactivity was measured weekly. To computed induced radioactivity using DCHAIN-SP, the neutron energy spectrum was computed using the LHD model with the Monte-Carlo simulation code PHITS. Although the calculated and measured radioactivity of 58Co and 54Mo agreed well, the calculated values of 60Co and 99Mo were underestimated. However, low-energy components could be improved by incorporating peripheral devices into the LHD model, resulting in more accurate radioactivity predictions.
Keywords
neutron, induced radioactivity, activation, LHD, decommissioning
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