Japan Atomic Energy Agency

Observation of relativistic bond weakening in seaborgium hexacarbonyl

Abstract The seventh row of the periodic table of the elements has been completed with the discovery of the five heaviest elements from flerovium (Fl, Z = 114) through oganesson (Og, Z = 118) 1 . Chemical properties of the superheavy elements (SHE, Z ≥ 104) are unique owing to th...

Toward AI-agent-driven particle transport simulations: implementation of AI-assisted workflows for PHITS

Monte Carlo particle transport codes are powerful tools, but their use requires substantial knowledge of input preparation, execution, and result analysis. In this study, we present a code-side strategy for applying existing AI assistants and AI agents to PHITS. Two complementary...

Water Activity Governs Ice Nanocrystal Evolution in Rapidly Frozen Sugar Solutions

Abstract Formation and evolution of ice nanocrystals in rapidly frozen sugar solutions were investigated using spin-contrast-variation small-angle neutron scattering (SCV-SANS). As the sugar concentration decreased, the SCV-SANS signal from nanocrystalline ice plates decreased re...

Framework nanoarchitectonics of fullerene-derived catalyst

In this review article, we examine the significance of developing catalysts via nanoarchitectonics by focusing on fullerenes as the primary material and frameworks as the nanoscale structural motif. Nanoscale frameworks such as C 60 , MOFs, and 2D carbon networks enable a precise...

Development and characterization of low-scattering vanadium nanoparticle targets for short-range interaction searches

We developed high-purity vanadium-based nanoparticle targets for neutron scattering experiments aimed at exploring gravity-like short-range new interactions in the submicron regime. Vanadium and V-Ni nanoparticles were fabricated using top-down and bottom-up methods and quantitat...

Estimation of global population-weighted annual eye lens dose from cosmic ray exposure.

This study presents the application of an analytical model, PARMA, to estimate the population-weighted annual absorbed dose to the lens of the eye due to cosmic rays. Cosmic ray flux data incorporating geographical altitude, together with the global population data from 2020, wer...

Liquid–Metal-Induced Metal–Support Interactions for CO2 Hydrogenation

Abstract Metal–support interaction (MSI) is central to numerous industrial heterogeneous catalytic processes yet its classical realization typically requires high-temperature treatment (typically >500 °C), which often induces metal sintering and excessive encapsulation. Herein, w...

Amorphous Tungsten Driving Extraordinary Long‐Range Interlayer Exchange Coupling and Large Spin‐Orbit Torque

ABSTRACT Artificially‐designed magnetic hetero‐structures with an antiferromagnetic alignment of magnetization in magnetic layers, which exploit the interlayer exchange coupling (IEC) through a non‐magnetic layer, are called synthetic antiferromagnets (SyAF) and are a treasure tr...

Deformable precipitates locally modify fault-mediated plasticity for strength-ductility synergy

Precipitates in structural alloys are conventionally understood as passive obstacles to dislocation motion. Here we show that semi-coherent hexagonal close-packed precipitates in a low-stacking-fault-energy Ni50Co30Ru20 multi-principal element alloy cooperate with planar-fault pl...

Improved core design and integrated back-end fuel cycle scheme for 200 MWt marine molten chloride fast reactor

This study presents an improved core design and the introduction of integrated back-end fuel cycle scheme for a 200 MWt Molten Chloride Fast Reactor (MCFR) intended as nuclear marine propulsion. The objective is to increase fuel burnup and reducing uranium consumption whilst main...

Development of the three-dimensional CFD model of heat exchanger type steam reformer for hydrogen production

A helium-heated multi-tube steam reformer is required for large-scale hydrogen production utilizing high temperature gas-cooled reactors (HTGRs). However, scale-up of the reformer causes axial and radial temperature distributions, which affect reaction rates and hydrogen producti...

Structure-Guided Enhancement of High-Temperature Thermoelectric Performance in Molten-Salt-Derived Weathered Biotite for Waste-Heat Recovery

Abstract Thermoelectric materials capable of operating at 600–900 °C are attractive for recovering industrial and nuclear waste heat toward a carbon-neutral society. Here, we report the structure-guided enhancement of high-temperature thermoelectric performance in natural weather...

Safety design approach for sodium-cooled fast reactor coupled to thermal energy storage system with sodium-molten salt heat exchanger improving heat transfer performance

A sodium-cooled fast reactor (SFR) can make flexibility with variable renewable energy by coupling a thermal energy storage (TES) system with molten salt. One of technical issues for the SFR coupled with TES is a heat exchanger (HX) between sodium and molten salt. In particular,...

Decoupling skeleton stability and water dynamics in C–S–H by in situ SAXS and H2O/D2O-atmosphere SANS

Humidity-induced microstructural changes in calcium silicate hydrate (C–S–H) have been widely studied by small-angle X-ray scattering (SAXS) and proton nuclear magnetic resonance (1H NMR) relaxometry; yet neither technique has been able to separate the contributions of the Ca–Si...

Direct speciation of ultra-trace platinum in marine ferromanganese oxides by wavelength-dispersive XAFS

Abstract Ultra-trace platinum (Pt) in marine ferromanganese oxides (FMOs) has remained inaccessible to direct XAFS analysis because of its extremely low abundance and severe interferences from co-existing elements. We achieved the first direct speciation of Pt at the 1 μg g−1 lev...

Neutron Source Localization Using Plate-Shaped Fast Neutron Detectors

To ensure nuclear security at major public events, portable detectors are essential for surveying wide areas and verifying the absence of nuclear and radioactive materials. Fast neutron detectors enable surveys for localizing neutron-emitting sources and nuclear materials over wi...

Antiferromagnetic order and crystalline electric field in noncentrosymmetric hexagonal R E Ru 6 As 4 ( R E = Sm and Yb )

We investigated the electronic properties of $RE{\mathrm{Ru}}_{6}{\mathrm{As}}_{4}(RE=\mathrm{La}, \mathrm{Ce}, \mathrm{Sm}, \text{and} \mathrm{Yb})$ using single-crystalline samples grown by the Bi-flux method. These compounds crystallize in the noncentrosymmetric hexagonal ${\m...

Analysis of molten particles from the Moto-Ujina Beach, Hiroshima

Abstract Color-sorted spherical molten particles extracted from Moto-Ujina Beach sand were analyzed by inductively coupled plasma–mass spectrometry, thermal ionization mass spectrometry, micro-PIXE analysis to obtain the elemental concentrations, 235 U/ 238 U isotope ratios, and...

Prediction of plutonium content of BWR/MOX fuel using a neural network

The Nuclear Material Balance (NMB) code is a comprehensive nuclear fuel cycle simulator developed by the Institute of Science Tokyo and the Japan Atomic Energy Agency. By modeling a fleet of reactors, fuel cycle simulators like NMB can help to optimize uranium and plutonium utili...