The Nuclear Material Balance [1] (NMB) code is a nuclear fuel cycle simulator developed by the former Tokyo Institute of Technology (present Institute of Science Tokyo) and the Japanese Atomic Energy Agency. The code allows the simulation of the full nuclear fuel cycle, including front-end, reactor and back-end operations for an extended number of reactor designs, fuels, reprocessing and...
In fusion reactors, large angle neutron scattering reactions significantly affect neutronics calculations, particularly for the reactor blanket. Previous integral experiments for large angle scattering cross section data at JAEA/FNS revealed discrepancies between experimental and calculated values [1]. Therefore, benchmarking studies on large angle scattering cross sections were indispensable....
Currently, several approaches have been investigated for dose evaluation in the boron neutron capture therapy (BNCT). (1) In clinical practice, the absorbed dose is typically evaluated using the gold wire activation technique combined with pre-treatment PET scans, which provide both the neutron flux and boron concentration. (2) Another approach introduces MRI-sensitive structures, such as...
A series of critical experiments was implemented on a mockup PWR-type fuel assembly loaded with B4C neutron absorber rods (B4C rods) in a tank-type critical assembly (TCA) in 1983 [1]. The mockup assembly was a 15x15 lattice consisting of 204 UO2 fuel rods with 3.2 wt% enrichment and 21 water holes. It was surrounded by a driver lattice region composed of 2.6 wt% enrichment UO2 fuel rods. In...
Fast neutron detection plays an essential role in various fields, including nuclear data measurement, radiation shielding design and dose evaluation. In fast neutron measurements, gamma-rays are typically accompanied by neutrons in the radiation field, requiring effective neutron-gamma (n-g) discrimination. For this reason, organic scintillators are widely used because of their fast response...
In this study, we evaluated and improved the simulation method of the DD neutron field in the OKTAVIAN facility at Osaka University, aiming to establish it as a standard neutron field. In previous studies [1], discrepancies were observed between the experimental angular distribution of DD neutron intensity and simulation results. To address this issue, we developed a new 3D simulation method...
Ensuring the security of nuclear reactor facilities is one of the most pressing challenges in the nuclear field. Theft or illegal transport of nuclear materials, and sabotage of nuclear facilities, are serious threats to safety and stability. Addressing these risks requires technologies that can detect and identify nuclear materials without damaging them. However, existing approaches have been...
Charge-changing cross section ($\sigma_{\mathrm{CC}}$) measurements play an essential role in advancing our understanding of nuclear structure. In heavy-ion beam experiments, atomic number ($Z$) identification is performed by combining the measurement of energy loss ($\Delta E$) with that of the particle velocity ($\beta$). Under typical conditions, the flight path is long enough to determine...
To calculate reliably and accurately concentrations and activities for nuclides generated or depleted by neutron reactions and radioactive decays in nuclear fuel, it is necessary to use the updated nuclear decay data such as half-lives, branching ratios, and $\gamma$-ray spectra. The Evaluated Nuclear Structure Data File (ENSDF) contains required decay data for all nuclides, which is...
The electron linear accelerator at the Institute for Integrated Radiation and Nuclear Science, Kyoto University (KURNS-LINAC) is an L-band accelerator installed in 1965. In nuclear data measurements at KURNS-LIAC, pulsed neutron sources consisting of a water-cooled tantalum target as a photo-neutron source and light water moderators were used. The time resolutions of those pulsed neutron...
The charge radius of an atomic nucleus is an important physical quantity representing its size. By considering the charge distribution of nucleons, it can be converted into the radii of the proton density distribution within the nucleus. Charged radii have been derived from measurements of electron scattering and isotope shifts; however, due to experimental limitations, the measurable nuclides...
In heavy-ion beam experiments, the charge-state distribution of ions after passing through materials is an important quantity for improving the accuracy of beam transmission efficiency and interaction cross-section measurements. In the transmission method for measuring interaction cross sections, precise prediction or measurement of the charge-state distribution is essential to ensure...
As a material-damage index due to the radiation, displacement per atom (dpa) is used widely, which is given by the particle fluence and the displacement cross section, which can be obtained by the electrical resistivity change of target materials due to the proton irradiation by the Matthiessen rule. The sample had to be cooled at cryo-temperature to observe the very small resistivity change...
The interaction cross section (σI) is a fundamental observable that provides valuable information about the spatial extent of atomic nuclei and can be used to derive the nuclear matter radius. By determining nuclear radii, we can improve our understanding of nuclear structure and how nuclear size changes across the nuclear chart.
Traditionally, nuclear charge radii have been obtained from...
Se-79 produced during the operation of nuclear reactors needs to be disposed with transmutation technology due to its high radioactivity and geological migration. For developing reasonable transmutation scheme, it is important to improve the accuracy of Se-79 neutron capture cross section. Despite its importance, there is still almost no experimental data available for capture cross section...
In Accelerator-Driven systems (ADS), reliable cross-section data for fast neutron interacting with radioactive waste are essential for improving the prediction accuracy of transmutation performance [1]. Due to the high radiotoxicity of the waste, it is difficult to use it directly as a target; therefore, a neutron target is desired. However, the fabrication of a stable neutron target is not...
The nuclear force that forms the nuclei is described as interactions between nucleons. The three-nucleon force (3NF) acting among three nucleons is essential to provide descriptions for various nuclear phenomena with high precision. Among the components of the 3NF, the spin-dependent part is still insufficiently understood [1]. To investigate spin-dependent parts of 3NFs, we are planning the...
The three-nucleon force (3NF) is crucial for understanding various nuclear properties, including the binding energy of light nuclei and observables in few-nucleon scattering. In few-nucleon scattering, 3NF effects have been observed in the cross section for deuteron-proton elastic scattering at around 100 MeV/nucleon [1]. 3NF effects have been observed in the cross section for deuteron-proton...
Accurate fission product yield (FPY) data are essential for reactor design and safety studies. Existing nuclear data libraries provide FPY only at limited neutron energies, leaving large gaps in the intermediate region that affect predictions for accelerator-driven systems (ADS) and advanced reactors. We developed a physics-informed machine-learning model using a Bayesian Neural Network (BNN)...
A preliminary benchmark study has been conducted to investigate the large-angle neutron scattering cross section of liquid nitrogen (LN₂). This work is motivated by the crucial role of nitrogen as a constituent nuclide in several materials used for the blanket and shielding systems of fusion reactors. Despite its importance, existing nuclear data for nitrogen remain insufficiently accurate,...
Isomer production is important in nuclear applications, such as radiation safety and radioactive waste management, and theoretical nuclear physics, such as level structure. Although the isomer production can be described by EBITEM [1] in PHITS [2], the number of reactions used as benchmarks is limited. Thus, further verification of the EBITEM’s performance is essential.
To confirm the...
Chromium (Cr) matters from two perspectives. In reactors, Cr is a major alloying element in stainless steels throughout cores and internals. Its 1--100 keV neutron-capture cross section directly affects reaction rates and $k_{\mathrm{eff}}$ [1]. In astrophysics, accurate MACS are crucial for modeling nucleosynthesis [2]. However, current datasets and evaluations show discrepancies in this...
The cross sections of neutron-induced charged-particle emission reactions such as (n,p) and (n,α) for many nuclides have not been measured as well as those of the neutron capture reaction. In the present work, building upon our previous confirmation of the feasibility of the sample-added scintillator technique for detecting neutron-induced charged-particle emission reactions, we plan to extend...
The history of element synthesis (Z>92) began with the discovery of $_{93}$Np in 1940. Since then, elements up to $_{118}$Og have been officially recognized. The superheavy elements from $_{114}$Fl to $_{118}$Og were first successfully synthesized directly using a $^{48}\text{Ca}$ projectile. However, this approach is considered impractical for element 119 due to the extreme difficulty in...
This study used the CoH$_3$ code [1] to perform a theoretical interpretation of neutron double-differential cross-sections (DDXs) for two nuclei, Tantalum (Ta) and Bismuth (Bi) [2-3], with the goal of investigating the underlying reaction mechanisms. We modified the exciton model by introducing a phenomenological factor to govern the transition rate from the initial, simple configuration to...
