CNRF is a neutron radiography facility that uses cold neutrons installed in the JRR-3 beam hall. After JRR-3 resumed operations in 2021 following a 10-year shutdown, only an imaging system using imaging plates (IPs) was available at the CNRF. Although high-resolution images could be acquired, the system was unsuitable for continuous imaging required for computed tomography (CT) scans and dynamic imaging. Additionally, performing quantitative analysis from these images was difficult. Thus, we have introduced a new imaging system with a light-tight box, scintillator, and CMOS camera. We demonstrated the performance of the system using a new Gd test pattern. The developed camera system successfully obtained the transmission images of the test pattern. Additionally, the spatial resolution of the system was estimated to be approximately 60 µm. In contrast, CNRF was not suitable for CT imaging etc. owing to its poor L/D value, and the neutron beam must be enhanced in future research.

Abstract We present a new method for paleomagnetic investigations, polarized neutron imaging, a non‐destructive magnetic imaging technique benefiting from the high penetration depth and spin of the neutron allowing spatial characterization of the magnetic field within a sample. We showcase the general capabilities of the technique by performing 3D vector tomography reconstructing the full magnetic field inside a 10 mm × 13 mm × 2 mm fragment of the remagnetized Martian meteorite NWA 7034. This was done in preparation for the Mars sample return mission where the orientation of samples on Mars is known. The magnetic field was measured with a spatial resolution of 215 μm and lower field bound of 0.5 mT mm.

Local variations in residual stress/strain and microstructure during fatigue crack growth in compact tension specimens of SUS304 austenitic stainless steel were investigated using complementary methods: pulsed neutron Bragg-edge imaging (NBEI), neutron diffraction (ND), digital image correlation (DIC) and electron backscatter diffraction (EBSD). Surface strain fields were evaluated using DIC and EBSD. NBEI provided two-dimensional averaged microstructure information, whereas ND yielded detailed three-dimensional distributions of residual lattice (elastic) strain and stress. This study particularly focused on how NBEI is helpful in understanding overall damage characteristics in the vicinity of a crack tip two-dimensionally. Distribution of microstructural parameters associated with crack growth, such as lattice constant, crystallite size, and texture, across the entire specimen was considered using Bragg-edge spectral analysis. The plastic zone in front of the crack tip, characterized by reduced crystallite size, was observed during crack propagation. After final fracture, two distinct zones with reduced crystallite size were identified: one caused by localized plastic deformation near the crack tip, and the other by bending at the back end of the specimen. This paper introduces the four experimental techniques and describes their respective features. Each method has its own advantages and limitations; However, by integrating their results, a more comprehensive understanding of the overall stress/strain field can be achieved.

Anodic Ti-based porous transport layers (PTLs) are paramount for advancing high-efficiency proton exchange membrane water electrolyzers (PEMWEs). One of the major challenges with the development of PEMWE is the PTL/catalyst layer interface passivation, which is commonly alleviated by coating precious metals such as Pt. Herein, we report, for the first time, the usage of polarized neutron imaging (PNI) on a half-half PTL approach to investigate current distribution inside the PTL layer under the influence of Ti passivation under PEMWE operando condition. First, the electrochemical study of PEMWE reveals an obvious advantage of Pt coating in preventing Ti passivation by showing 822 mV less overpotential at 1 A cm-2 (1.771 V) for the superior sample (Pt-coated PTL) compared to the PEMWE with pristine Ti PTL (2.539 V). Second, it is confirmed that using ex situ electronic and structural characterizations, Ti passivation cannot be recognized, suggesting a temporary passivation process in an operating PEMWE. Employing PNI for operando mapping of the current distribution inside the PEMWE shows that most of the electrical current favors the Pt-coated PTL, perfectly aligned with the results obtained from the high-resolution operando neutron radiography in which around 60% of the produced oxygen was found in the Pt-coated PTL.

A neutron resonance absorption imaging technique to visualize two-dimensional distributions with element discrimination has been developed at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex. We measured neutron transmission spectra from 1 eV to 100 keV while rotating a sample containing iron, zirconium, nickel, molybdenum, and aluminum rods. The distributions of hafnium (impurity of zirconium) and molybdenum were clearly obtained by a straightforward analysis using the most prominent resonances. Then an analysis using multiple resonances of each element simultaneously was performed finding that the accuracy of elemental identification was improved, and iron and nickel distributions became clearer. However, these analysis methods sometimes have difficulties in the case of overlapping materials since a resonance shape can be deteriorated by those of other materials. Such an example was demonstrated with the case of iron and nickel. To overcome the issue and aiming for further improvement, we proposed a method to fit the transmission spectrum in a wide range assuming the existence of possible elements, successfully visualizing both the distributions of the sample metals and those of hafnium and manganese (impurities of zirconium and iron). The newly introduced analysis technique will contribute to the establishment of a standard analytical procedure for general users of the facility.

Determining temperatures with small uncertainties is important for neutron thermometry, which is required for both fundamental science and industrial applications. Conventionally, neutrons transmitted through a sample in shielded materials are detected. The sample temperature is then derived by analyzing the energy dependence of the transmission neutrons at resonances influenced by the Doppler-broadening effect. However, reducing the temperature-determination uncertainty is extremely hard with the conventional method, because it is determined only by the small changes at the resonances, i.e., temperature-sensitive components, compared to the primary neutrons. Therefore, we propose a new thermometry named neutron self-indication thermometry (NSIT), which combines the Doppler-broadening effect with a self-indication technique that irradiates the sample and an indicator containing the same nuclide as the sample. The NSIT can enhance temperature sensitivity by measuring prompt gamma-rays to indirectly obtain the temperature-sensitive components at resonances by employing the same resonance twice. The temperature sensitivity and uncertainty of the NSIT were compared with those of the conventional method by varying the sample temperatures from 23.0 degrees C to 492.6 degrees C. The results demonstrated that the NSIT was approximately 1.6 times more sensitive and had lower uncertainty in determining temperature. These findings highlight the potential of the NSIT as an effective alternative to remote thermometry.

Tracer diffusion coefficients of lithium-ions in the sintered samples of Li1.5Al0.5Ge1.5(PO4)(3) (LAGP) have been measured through the neutron radiography (NR) technique in the wide temperature range from 25 degrees C to 500 degrees C. The diffusion data above and below 300 degrees C were collected using pulsed and reactor-generated neutrons, respectively, which coincide with each other at 300 degrees C exhibiting a single curve in the Arrhenius plot. The roomtemperature diffusion coefficient and the activation energy below 300 degrees C are obtained as 1.47 x 10(-9) cm(2) s(-1) and 0.37 eV, respectively. The activation energy of the conductivity diffusion coefficient almost agrees with the tracer one, and the deduced Haven ratio of 0.40 is consistent with the concerted migration model of the lithiumions.

The energy-resolved neutron imaging system, RADEN at J-PARC, has been providing to users a Rietveld-type analysis code, RITS, for pulsed neutron Bragg-edge transmission (BET) imaging with a graphical user interface (GUI) version, for fitting spectral data obtained with this instrument. In the last year, we updated the computational platform of GUI-RITS software from Scientific Linux 6 (SL6) and Python 2 to Windows 10 and Python 3, and added some functions to improve usability. The license agreement for this updated software is the Berkeley Software Distribution (BSD) 2-Clause License (non-copyleft) and is currently available for download from the RADEN website.

The compressive residual stress on the gear tooth's surface, a vital parameter to control mechanical properties, such as strength, has a beneficial effect on the component's fatigue life. A novel procedure, double induction quenching (DIQ), effective for improving the fatigue strength of gear products, has been used for producing gears with steep gradients of compressive residual stress generated in the tooth surface. We performed a Bragg edge imaging experiment at a pulsed neutron source to determine the spatial distribution of the {110} lattice spacing (d110) and the broadening of the {110} Bragg edge (w110) on the DIQ gear product after tooth-bending fatigue tests to which different loading cycles were applied. No significant difference occurred in the d110 and the w110 at Hofer's critical section (tensile side) of the teeth with different loading conditions within the accuracy of data analysis. However, we detected a decrease in the w110 and changes in the residual lattice strain distribution in the axial direction (through the thickness) along the tooth root directions at the opposite side of Hofer's critical section for both teeth after 3 x 105 and 8 x 105 cycles, relieving the compressive residual stresses during the fatigue process. The residual stress close to the gear tooth surface determined by X-ray diffraction using sequential polishing showed a slight relaxation and redistribution from the tensile side in the hoop direction, complementary to the neutron Bragg edge imaging information in the axial direction.

Boron areal densities in pure boron samples were determined using energy-resolved neutron measurements. For non-destructive measurement of boron content, the neutron-energy spectrum was measured with prompt γ -ray activation analysis. It was confirmed that the areal density of samples could be measured with 1% to 10% accuracy for high boron content by neutron energy spectrum analysis. The viability of this analysis is also discussed compared with the traditional quantitative analysis.

To develop a lead-bismuth eutectic (LBE) cooled nuclear reactor , phase transition phenomena of LBE are very important. In the solidification of LBE, the crystalline structure is varied with the cooling process. The volumetric expansion of LBE must be clarified for the safety of an LBE cooled nuclear reactor. The time dependence of the volumetric expansion depends on the crystalline microstructure. In this study, the crystalline microstructure of the LBE samples solidified with the different cooling processes was investigated by the neutron Bragg edge imaging technique. Spatially integrated and local microstructure characteristics of LBE samples were analyzed. Characteristics of preferred orientation of LBE microstructure were clarified.

To determine neutron capture cross-sections and elemental/isotopic compositions accurately via neutron capture reactions, shape effects caused by uniformity of samples must be considered. However, the estimation of shape effects is difficult to verify in some cases: sealed samples and valuable objects. In this study, the effects on sealed radioactive samples were estimated experimentally. A capability of energy-resolved neutron imaging enabled us to confirm significant localization of the sealed 129I sample non-destructively. It is revealed that shape effects should be corrected for obtaining accurate experimental results. Consequently, we conclude that energy-resolved neutron imaging will be effective to improve analytical accuracy.

Lithium tracer diffusion coefficients have been measured in Li1.3Al0.3Ti1.7(PO4)(3) (LATP) and LATP - LaPO4 composite solid electrolytes in the temperature range between 300 degrees C and 500 degrees C by means of neutron radiography technique that utilizes the difference in neutron attenuation of 6Li and 7Li isotopes. The diffusion coefficient of LATP - LaPO4 composite is higher than that of pristine LATP, although the difference is much smaller than that estimated from the room temperature conductivity. This suggests that the bulk diffusion becomes the predominant diffusion mechanism at 300 degrees C to 500 degrees C instead of the diffusion along the space charge layer formed around the LaPO4 dispersants.

In this paper, we have studied an additively manufactured metallic component, intended for ultra-high vacuum application, the exit-snout of the MACHINA transportable proton accelerator beam-line. Metal additive manufacturing components can exhibit heterogeneous and anisotropic microstructures. Two non-destructive imaging techniques, X-ray computed tomography and Neutron Tomography, were employed to examine its microstructure. They unveiled the presence of porosity and channels, the size and composition of grains and intergranular precipitates, and the general behavior of the spatial distribution of the solidification lines. While X-ray computed tomography evidenced qualitative details about the surface roughness and internal defects, neutron tomography showed excellent ability in imaging the spatial density distribution within the component. The anisotropy of the density was attributed to the material building orientation during the 3D printing process. Density variations suggest the possibility of defect pathways, which could affect high vacuum performances. In addition, these results highlight the importance of considering building orientation in the design for additive manufacturing for UHV applications.

A spallation neutron source using mercury has been operated since 2008 on J-PARC. In the mercury, radioactive nuclide including tritium have been produced. The target vessel made of stainless steel is required to be exchanged periodically. In this paper, we report tritium behavior observed in series of the first exchange work done in 2011. Analysis on the tritium release behavior from the stainless steel on the basis of a simple desorption models was also shown.