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Verification of the Thermal Neutron Shielding Effect of the Shielding Door of the LHD Experimental Hall

Takuya SAZE, Hitoshi MIYAKE and Minoru SAKAMA¹⁾

National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 Japan

1)

Department of Radiation Physics, Engineering and Biology, Division of Biomedical Information Sciences, Institute of Health Biosciences, The University of Tokushima, Tokushima 770-8509, Japan

(Received 5 July 2018 / Accepted 11 July 2018 / Published 10 August 2018)

Abstract

Evaluating the performance of the shielding walls and shielding doors at radiation facilities is important to ensure proper radiation safety management. In the first period of the deuterium experiment, the neutron-shielding ability of the shielding door of the experimental hall containing the large helical device (LHD) was evaluated using the gold-foil activation method. The gold foil was inserted into a small gap between the shielding door and the shielding wall. Meanwhile, the shielding effect of the wall against the neutrons and gamma rays was verified using the badge-type dosimeters that were placed both inside and outside the experimental hall near the wall. The radiation derived from Au-198, which was visualized using by imaging plate, reached approximately 35 cm inside the shielding door. The results provided visual evidence that the shielding door safely excluded the thermal neutrons that were generated in an LHD. Furthermore, the measurement results of the badge-type dosimeters confirmed that the neutrons and gamma rays were completely trapped by the concrete wall of the experimental hall.

Copyright (c) 2018 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

thermal neutron, gold foil activation method, imaging plate, shielding door, LHD, deuterium experiment

DOI: 10.1585/pfr.13.1205101

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References

• [1] Y. Takeiri, T. Morisaki, M. Osakabe et al., Nucl. Fusion 57, 102023 (2017).
• [2] M. Sakama, Journal of the Korean Physical Society 59, No. 2, 1995 (2011).
• [3] T. Saze et al., Nucl. Instrum. Methods A. 406, 343 (1998).
• [4] T. Saze et al., Nucl. Instrum. Methods Phys. Res. A 443, 578 (2000).
• [5] S.F. Mughabghab et al., Neutron Cross Sections - Vol. 1. (Academic Press, Inc., New York, 1981).
• [6] Schmidt FAR., The attenuation properties of concrete for shielding of neutrons of energy less than 15 MeV., Oak Ridge National Laboratory, Oak Ridge, TN, 1970.