Evaluation of neutron attenuation properties using helium-4 scintillation detector for dry cask inspection

• Published in: Nuclear engineering and technology Vol. 55; no. 9; pp. 3506 - 3513
• Main Authors: Moon, Jihun, Kim, Jisu, Chung, Heejun, Kwak, Sung-Woo, Lim, Kyung Taek
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2023; Elsevier; 한국원자력학회
• Subjects: dry cask; Helium-4 detector; Neutron detection; Neutron shielding; S670e; 원자력공학; S670e; dry cask; Neutron shielding; Helium-4 detector; Neutron detection
• ISSN: 1738-5733; 2234-358X
• DOI: 10.1016/j.net.2023.06.039

In this paper, we demonstrate the neutron attenuation of dry cask shielding materials using the S670e helium-4 detector manufactured by Arktis Radiation Ltd. In particular, two materials expected to be applied to the TN-32 dry cask manufactured by ORANO Korea and KORAD-21 by the Korea Radioactive Waste Agency (KORAD) were utilized. The measured neutron attenuation was compared with our Monte Carlo N-Particle Transport simulation results, and the difference is given as the root mean square (RMS). For the fast neutron case, a rapid decline in neutron counts was observed as a function of increasing material thickness, exhibiting an exponential relationship. The discrepancy between the experimentally acquired data and simulation results for the fast neutron was maintained within a 2.3% RMS. In contrast, the observed thermal neutron count demonstrated an initial rise, attained a maximum value, and exhibited an exponential decline as a function of increasing thickness. In particular, the discrepancy between the measured and simulated peak locations for thermal neutrons displayed an RMS deviation of approximately 17.3–22.4%. Finally, the results suggest that a minimum thickness of 5 cm for Li-6 is necessary to achieve a sufficiently significant cross-section, effectively capturing incoming thermal neutrons within the dry cask.