Fissile nuclear material identification in shielding conditions using a neutron resonance analysis technique

Volume: 67, December 2025, pages 59-67

Authors: Fabiana Rossi ^a, Jaehong Lee ^a, Yuki Yoshimi ^b, Kota Hironaka ^a, Mitsuo Koizumi ^a, Tomooki Shiba ^a, Kazushi Terada ^c, Jun-ichi Hori ^c

^a Japan Atomic Energy Agency, Integrated Support Center for Nuclear Non-proliferation, Security and Human Resource Development, 2-4 Shirane, Tokai-mura, Ibaraki, Japan, 319-1195
^b OUTSOURCING TECHNOLOGY Inc.、Marunouchi Trust Tower Main 16 & 17F, 1-8-3 Marunouchi, Chiyoda-ku, Tokyo 100-0005, Japan
^c Kyoto University, Institute for Integrated Radiation and Nuclear Science, 2-1010 Asashiro-Nishi, Kumatori-cho, Osaka 590-0494
 

Abstract: The Japan Atomic Energy Agency's Integrated Support Center for Nuclear Non-proliferation, Security and Human Resource Development is developing an advanced neutron resonance analysis system for the identification and quantification of fissile materials. This system integrates three complementary techniques: neutron resonance transmission analysis, neutron resonance capture analysis, and neutron resonance fission neutron analysis. High-energy neutrons generated using the electron linear accelerator beamline at the Institute for Integrated Radiation and Nuclear Science of Kyoto University, are moderated and directed through a series of collimators to the experimental area, where the sample is positioned. Surrounding the sample, plastic scintillators with neutron-gamma pulse shape discrimination capabilities allow for the collection and analysis of prompt gamma rays and fission neutron signals, while un-scattered neutrons passing through the sample are detected by a downstream glass scintillator. We conducted a series of experiments using natural uranium samples with different thicknesses enclosed in lead shielding. The results show that even if the presence of lead generates significant background noise due to neutron scattering and reflection, a clear identification of ²³⁵U signatures is possible. These findings highlight the system’s versatility and effectiveness in shielding scenarios, offering a promising tool for nuclear security and non-proliferation applications.

Keywords: neutron resonance, natural uranium, mass correlation, safeguards, non-proliferation

Reference guideline: Rossi, F., Lee, J., Yoshimi, Y., Hironaka, K., Koizumi, M., Shiba, T., Terada, K., Hori, J., ( 2025). Fissile nuclear material
identification in shielding conditions using a neutron resonance analysis technique, ESARDA Bulletin - The
International Journal of Nuclear Safeguards and Non-prol iferation, 67, 59-67.
https://doi.org/10.3011/ESARDA.IJNSNP.2025.5