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Rare-earth phosphor materials have been investigated for several decades due to their high X-ray absorption coefficient and emission efficiency, but these materials tend to reveal lower resolution and packing density when fabricated in bulk. In this work, we investigated the BaFBr:Eu2+ micro/submicro/nano-crystal phosphor material prepared using a precipitation method, and we demonstrate the dependence of the optical properties of these phosphors on the annealing temperature and Eu2+ concentration. The optimum preparation conditions were determined to be an annealing temperature of 600 °C for 2 h and an Eu2+ doping concentration of 0.1 mol%, achieving a quantum yield of 53.19%. Furthermore, the average lifetime is 669 ns. In comparison with typical bulk phosphors, the shape and size distribution of the crystallites, which is about 100 nm on average, may improve the resolution and enhance the fluorescence performance. The results of this study thus offer a new strategy for the development of highly efficient storage phosphors.

A moveable multi-use neutron imaging facility was constructed based on a compact accelerator D-T neutron source, for use in thermal and fast neutron radiography and tomography. Experiments were carried out to investigate the imaging quality for different standard samples. The smallest width of a slit that can be tested by digitized thermal neutron radiography was found to be 0.06 mm, while the smallest diameter of holes tested by digitized fast neutron radiography was 0.5 mm. A gadolinium wire of 0.2 mm in diameter within a multi-material structure was reconstructed clearly with thermal neutron tomography, and holes in a light material were reconstructed with fast neutron tomography.

In order to investigate the swelling behavior and fuel–cladding interaction mechanism of U–10Zr alloy metallic fuel at very low burnup, an irradiation experiment was concisely designed and conducted on the China Mianyang Research Reactor. Two types of irradiation samples were designed for studying free swelling without restraint and the fuel–cladding interaction mechanism. A new bonding material, namely, pure aluminum powder, was used to fill the gap between the fuel slug and sample shell for reducing thermal resistance and allowing the expansion of the fuel slug. In this paper, the concise irradiation rig design is introduced, and the neutronic and thermal–hydraulic analyses, which were carried out mainly using MCNP (Monte Carlo N-Particle) and FLUENT codes, are presented. Out-of-pile tests were conducted prior to irradiation to verify the manufacturing quality and hydraulic performance of the rig. Nondestructive postirradiation examinations using cold neutron radiography technology were conducted to check fuel cladding integrity and swelling behavior. The results of the preliminary examinations confirmed the safety and effectiveness of the design.

The inspection of the process of gas pressure change is important for some applications (e.g. gas tank stockpile or two phase fluid model) which need quantitative and non-touchable measurement. Neutron radiography provides a suitable tool for such investigations with nice resolution. The quantitative cold neutron radiography (CNR) is developed at China Mianyang Research Reactor (CMRR) to measure the hydrogen gas pressure with metal shield. Because of the high sensitivity to hydrogen, even small change of the hydrogen pressure can be inspected by CNR. The dark background and scattering neutron effect are both corrected to promote measurement precision. The results show that CNR can measure the hydrogen gas pressure exactly and the pressure value average relative error between CNR and barometer is almost 1.9%.

Based the China Mianyang Research Reactor (CMRR) and D-T accelerator neutron source, thermal neutron, cold neutron and fast neutron imaging facilities are all installed at China Academy of Engineering Physics (CAEP). Various samples have been imaged by different energy neutrons and shown the neutron imaging application in industry, aerospace and so on. The facilities parameters and recent neutron imaging development will be shown in this paper.

Coded source imaging (CSI) technique could increase the utilization rate of neutron when high L/D required in neutron imaging. The images need to be reconstructed from the raw projections. The reconstruction would amplify the noise of the raw projection, which will affect the quality of reconstructed images. Study of Signal to Noise Ratio (SNR) in CSI shows image quality depends on geometry structure and neutron beam parameters. With analysis method based on correlation reconstruction arithmetic, SNR was detailed to assess the effects from different geometry factors. Numerical simulation as a further supplement proves the rationality of analysis method. The comparison of SNR between CSI and traditional neutron radiography (NR) shows that the SNR of CSI could be better than NR in some conditions.

It is hopeful that fusion-fission hybrid energy system will become an effective approach to achieve long-term sustainable development of fission energy. U-10Zr alloy (which means the mass ratio of Zr is 10%) fuel is the key material of subcritical blanket for fusion-fission hybrid energy system which the irradiation performance need to be considered. Indirect neutron radiography is used to detect the irradiated U-10Zr alloy because of the high residual dose in this paper. Different burnup samples (0.1%, 0.3%, 0.5% and 0.7%) have been tested with a special indirect neutron radiography device at CMRR (China Mianyang Research Reactor). The resolution of the device is better than 50 µm and the quantitative analysis of swelling behaviors was carried out. The results show that the swelling behaviors relate well to burnup character which can be detected accurately by indirect neutron radiography.

Polarimetric neutron tomography provides a powerful tool for direct visualization of magnetic fields in the bulk of matter. However, the measurable field strength has been severely restricted because neutron spin precession angles have to be limited below π due to the phase wrapping problem. In this article we show that in most cases the spin precession limit can be extended by identifying and correcting discontinuities in the sinograms. We present an improved method so that Algebraic reconstruction technique can be applied in the precession interval [ π , 2 π ] to improve the reconstruction quality. Robustness of this method against device parameters and statistical noise has been studied through numerical simulation, some unexpected influence have been found and discussed.

To carry on neutron imaging researches (radiography/tomography), we built a Cold Neutron Radiography Facility (CNRF), based on the China Mianyang Research Reactor (CMRR) at Institute of Nuclear and Chemistry (INPC). This CNRF system utilizes cold neutrons from the C1 neutron guide. The facility consists of beam shutter, flight tubes, beam limiter, object handling system, imaging system, beam stop and data acquisition system. The maximum neutron flux at the sample position is 6 × 106 n/cm2/s, approximately. There are seven pinholes in the collimator system, to offer a possible L/D from 200 to 1300. With different imaging lenses, the imaging system could provide four different FOVs. The performance parameters are tested by Siemens Star and ASTM standard devices-beam purity indicator (BPI) and image sensitivity indicator (SI). Our results show the resolution of CNRF is better than 20 μ m (i.e. 25lp/mm), and its typical radiography image is of Category-I, as defined in ASTM E545.

Fast neutron radiography is a promising application for accelerator based neutron sources. The potential effectiveness of this technique depends on the development of suitable imaging detectors for fast neutrons. Zinc sulphide based scintillators have the largest light output per event in the family of imaging scintillators used so far in fast neutron radiography. This paper investigated different aspects of this scintillator in order to determine the factors which might affect the light output. A mathematical model was established to estimate effectiveness of this scintillator. Zinc sulphide screens were prepared with ZnS particles of different concentrations in polypropylene matrix. A 14 MeV fast neutron source was used in the experiments. The light output was detected using a CCD camera or a film coupled to the scintillator screen. The results showed that the optimum scintillators is around 3 mm in thickness with the weight ratio of 2:1 for ZnS and polypropylene.

14 MeV Fast neutrons has good penetrability and the 14 MeV fast neutron radiography can meet the need of Non-Destructive Test of the structure and lacuna of heavy-massive sample, whose shell is made of heavy metal and in which there are some hydrogen materials, and the study of fast neutron digital radiography just begins in China. By the use of a D-T accelerator, a digital imaging system made up of a fast neutron scintillation screen made of ZnS(Ag) and polypropylene, lens and a scientific grade CCD, the experimental study of fast neutron radiography has been done between 4.3×1010−6.8×1010 n/s of neutron yield. Some 14 MeV fast neutron digital radiographs have been gotten. According to experimental radiographs and their data, the performance of the fast neutron scintillation screen and the basic characters of 14 MeV fast neutron radiography are analyzed, and it is helpful for the further research.

Neutron radiography (NR) is one of the most important nondestructive testing methods, which is sensitive to low density materials. Especially, Neutron transfer imaging method could be used to test radioactivity materials refraining from y effect, but it is difficult to realize tomography. Coded source neutron imaging (CSNI) is a newly NR method developed fast in the last several years. The distance between object and detector is much longer than traditional NR, which could be used to test radioactivity materials. With pre-reconstruction process from fold-cover projections, CSNI could easily realize tomography. This thesis carries out preliminary study on the nuclear fuel element testing by coded source neutron imaging. We calculate different enrichment, flaws and activity in nuclear fuel elements tested by CSNI with Monte-Carlo simulation. The results show that CSNI could be a useful testing method for nuclear fuel element testing.