Neutronic characteristics of a partially damaged reactor model with varying numbers of damaged fuel assemblies

Nguyen, H. H.

Annals of Nuclear Energy, 230, p.112171_1 - 112171_13, 2026/06

https://doi.org/10.1016/j.anucene.2026.112171

This study examined the effects of the moderator-to-fuel volume ratio, fuel debris shape, and the number of damaged fuel assemblies on the neutronic characteristics of a partially damaged reactor model, where the fuel assemblies at the core center melt to fuel debris while the fuel assemblies at the outer region remain intact. The investigations were conducted using the Serpent code and the JENDL-5 library. The results show that when fuel debris is surrounded by intact fuel assemblies, the k can be classified into two groups based on the shape of the fuel debris. Conversely, in scenarios where the fuel debris is not fully encircled by intact fuel assemblies, the shape of the fuel debris has a negligible impact on the k. Additionally, the relationship between the number of neutrons entering and leaving the fuel debris determines how the shape of the fuel debris affects the k.

Pilot full-scale demonstration of a prototype table-top neutron resonance transmission analysis system for nuclear material detection

Guembou Shouop, C. J.; Tsuchiya, Harufumi

Communications Engineering (Internet), 5, p.11_1 - 11_14, 2026/01

https://doi.org/10.1038/s44172-025-00564-6

Development of nano-sized graphene flowers as neutron reflectors; Intensify neutron beam caused by coherent scattering

Teshigawara, Makoto; Ikeda, Yujiro*; Muramatsu, Kazuo*; Sutani, Koichi*; Kimijima, Koichi*; Fukuzumi, Masafumi*; Noda, Yohei*; Koizumi, Satoshi*; Kawamura, Yuji*; Saruta, Koichi; et al.

Canadian Journal of Physics, 103(12), p.1225 - 1231, 2025/12

https://doi.org/10.1139/cjp-2025-0088

Science using neutrons in the nanometer (nm) wavelength region as probes is expanding into a wide range of fields, from basic research in materials and life science to industrial applications. Dramatic increase in the intensity of the beam source is required to drive such research. We have focused on coherent scattering caused by nano-sized particle aggregations to increase the intensity of neutron beams. Nanodiamond is being vigorously researched and developed with the aim of practical application. On the other hand, we have focused on graphene, which has higher van der Waals forces by an order of magnitude and stronger bonding, sp2, between carbons than nanodiamond. This is expected to lead to its processability into a lumped for and to adapt to higher radiation fields. By promoting chemical vapor deposition (CVD), we have established a technique to form nano-sized graphene (called graphene flower) with a shape similar to a sunflower flower. In this talk, we report on the neutron scattering properties that contribute to the coherent scattering of the newly developed graphene flower.

Development of nuclear security technologies for a large public event (Collaboration research)

Takahashi, Tone; Mochimaru, Takanori*; Koizumi, Mitsuo; Yoshimi, Yuki*; Yamanishi, Hirokuni*; Wakabayashi, Genichiro*; Ito, Fumiaki*

JAEA-Review 2025-039, 34 Pages, 2025/11

JAEA-Review-2025-039.pdf:2.18MB

To prevent acts of terrorism involving nuclear or radioactive materials at major public events, it is required to have surveillance technologies that either prevent these materials from being brought in or detect quickly if somebody brings them in secretly. Setting radiation gate monitors to survey pedestrians and vehicles is one of the effective methods. However, considering the possibility of individuals bypassing these monitors, complementary technologies are needed to continuously survey areas inside the gates. To survey extensive areas, radiation mapping is effective. By using multiple detectors and aggregating the data, the survey becomes much more efficient. We have developed mobile detectors capable of simultaneously measuring location data and radiation levels outdoors, with the ability to aggregate measurement results via a network and immediately visualize them on a map. For indoor environments, we have developed a technology that integrates radiation measurement results with environmental mapping created using SLAM (Simultaneous Localization and Mapping) to produce 3D maps of the surveyed areas. Additionally, we have been working on the development of a source search technology using a fast neutron detector to quickly detect neutron sources, including nuclear materials. In this report, we describe a concept of the wide area survey system and report technology development results so far.

Re-evaluation of nuclear criticality characteristics for infinite and finite heterogeneous lattice systems composed of uranium-zirconium hydride fuel rods used in the TRIGA annular core pulse reactor NSRR

Yanagisawa, Hiroshi; Motome, Yuiko

JAEA-Research 2025-010, 197 Pages, 2025/11

JAEA-Research-2025-010.pdf:3.5MB

For understandings of nuclear criticality risks of TRIGA fuel rods and review of safety measures for handling them, nuclear criticality characteristics for infinite and finite heterogeneous lattice systems composed of the NSRR fuel rods were re-evaluated with the use of a detailed computational model for the fuel rod. The MVP version 3 code was used with the JENDL libraries including the latest version, JENDL-5, for the re-evaluation. As the criticality characteristics, variations of neutron multiplication factors of the infinite and water-reflected finite systems were examined in detail with parameters of the lattice pitch and density of moderator water. From the results of the re-evaluated criticality characteristics, the minimum critical number of fuel rods for the water-reflected hexagonal shaped lattice system was obtained to be 46.8 0.2 using the JENDL-5 library. Moreover, the attainability of criticality without the water as moderator and reflector was examined because the zirconium hydride moderator and graphite reflector are equipped with the TRIGA fuel rod. It was found that the criticality is possible to be attained by 115.7 0.6 of the number of fuel rods, which is the smaller number of fuel rods than loaded in the NSRR standard core, even though no water exists.

Real-space local dynamics in 1,2,3-triazole using inelastic neutron scattering

Shinohara, Yuya*; Iwashita, Takuya*; Nakanishi, Masahiro*; Liu, Y.*; Cooper, V. R.*; Kofu, Maiko*; Nirei, Masami; Dmowski, W.*; Hickner, M. A.*; Egami, Takeshi*

Journal of Physical Chemistry B, 129(47), p.12330 - 12337, 2025/11

https://doi.org/10.1021/acs.jpcb.5c06367

Production of Cu and Cu with accelerator neutrons by deuterons and their separation from zinc

Nagai, Yasuki*; Kawabata, Masako*; Saeki, Hideya*; Motoishi, Shoji*; Hashimoto, Kazuyuki; Tsukada, Kazuaki; Motomura, Arata*; Ota, Akio*; Takashima, Naoki*; Hashimoto, Shintaro; et al.

Frontiers in Nuclear Medicine (Internet), 5, p.1657125_1 - 1657125_11, 2025/10

https://doi.org/10.3389/fnume.2025.1657125

In recent years, the radionuclide pair of Cu and Cu has attracted attention as an ideal theranostic agent. We proposed a novel production method utilizing a neutron source generated by deuteron beams at an accelerator facility. By irradiating enriched Zn samples with this neutron source, we measured the absolute activity and radionuclidic purity of the produced Cu. The results were consistent with calculations performed using PHITS and JENDL-5 developed by the Japan Atomic Energy Agency, confirming the reliability of the calculation method and demonstrating its capability to estimate the yields of trace radionuclides that are difficult to measure experimentally. Furthermore, we successfully separated Cu from the irradiated Zn sample using our developed sublimation and column separation techniques. These findings suggest that the production of Cu and Cu can be achieved in an economically sustainable manner at multiple sites.

Corrigendum to "Neutron diffraction study on the deuterium composition of nickel deuteride at high temperatures and high pressures" [Phys. B Condens. Matter. 587 (2020) 412153]

Saitoh, Hiroyukki*; Machida, Akihiko*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Sato, Toyoto*; Orimo, Shinichi*; Aoki, Katsutoshi*

Physica B; Condensed Matter, 714, p.417234_1 - 417234_3, 2025/10

https://doi.org/10.1016/j.physb.2025.417234

Corrigendum to "Neutron diffraction study on the deuterium composition of nickel deuteride at high temperatures and high pressures" [Phys. B Condens. Matter. 587 (2020) 412153] was reported.

Advancing materials studies for high-power proton accelerators in J-PARC

Makimura, Shunsuke*; Matoba, Shiro*; Sunagawa, Hikaru*; Naoe, Takashi; Wakui, Takashi; Ishida, Taku*; Matsubara, Tsurayuki*; Fukao, Yoshinori*; Takahashi, Hitoshi*; Watanabe, Hiroaki*; et al.

Proceedings of 71st ICFA Advanced Beam Dynamics workshop on High-Intensity and High-Brightness Hadron Beams (HB2025) (Internet), p.359 - 363, 2025/10

https://meow.elettra.eu/83/pdf/FRIAA01.pdf

In modern proton accelerators, the survivability of beam-intercepting devices, such as targets, beam windows and beam dumps, under intense beam irradiation is a key factor limiting the achievement of higher beam power. This article introduces the challenges faced by the secondary particle production targets and beam windows at the Japan Proton Accelerator Research Complex (J-PARC), and the developments undertaken to overcome these challenges.

Enhanced work hardening in ferrite and austenite of duplex stainless steel at 200 K; neutron diffraction study

Yamashita, Takayuki*; Koga, Norimitsu*; Mao, W.*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Fujii, Hidetoshi*; Umezawa, Osamu*

Materials Science & Engineering A, 941, p.148602_1 - 148602_11, 2025/09

https://doi.org/10.1016/j.msea.2025.148602