Plasma and Fusion Research

Volume 17, 2405096 (2022)

Regular Articles

Evaluation of Induced Radioactivity Generated during LHD Deuterium Plasma Experiments
Sachiko YOSHIHASHI, Hayato YAMADA, Makoto KOBAYASHI1), Takeo NISHITANI, Atsushi YAMAZAKI, Mitsutaka ISOBE1), Kunihiro OGAWA1) and Akira URITANI
Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
(Received 7 January 2022 / Accepted 30 June 2022 / Published 24 August 2022)


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.


neutron, induced radioactivity, activation, LHD, decommissioning

DOI: 10.1585/pfr.17.2405096


  • [1] T. Nishitani et al., Plasma Fusion Res. 11, 2405057 (2016).
  • [2] T. Nishitani et al., Fusion Eng. Des. 123, 1020 (2017).
  • [3] Y. Nakano et al., Plasma Fusion Res. 9, 3405141 (2014).
  • [4] T. Tanaka et al., Fusion Eng. Des. 146, 496 (2019).
  • [5] T. Tanaka et al., Plasma Fusion Res. 14, 3405162 (2019).
  • [6] M. Kobayashi et al., Plasma Fusion Res. 15, 2405043 (2020).
  • [7] R.B. Firestone, Table of Isotopes, 8th edition (John Wiley & Sons, Inc., 1996).
  • [8] T. Sato et al., J. Nucl. Sci. Technol. 55, 684 (2018).
  • [9] K. Shibata et al., J. Nucl. Sci. Technol. 48(1), 1 (2011).
  • [10] O. Iwamoto et al., J. Korean Phys. Soc. 59(2), 1224 (2011).
  • [11] G. Chiba et al., J. Nucl. Sci. Technol. 48(2), 172 (2011).
  • [12] T. Kai et al., JAERI-Data/Code 2001-016. 3 (2001).
  • [13] P.J. Griffin et al., User's Manual for SNL-SAND-II Code, Sandia National Labs (1994).