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There has been an urgent demand for novel neutron shielding materials (NSMs) with high mechanical strength and low acid corrosion rate to be used in compact shielding design. In this contribution, BPO4 ceramics (BPCs), one of the candidates for such materials, was successfully fabricated by a two-step method using H3BO3 and H3PO4 as raw materials. The evolution of the microstructures was then investigated, followed by testing of mechanical/thermal properties, acid corrosion resistance, and neutron shielding performance. The experimental results indicated that the calcination temperature as well as H3BO3 content in raw materials intuitively affected the densification process of the BPCs. The as-pared BPCs showed reliable mechanical properties with maximum CMOR, compressive strength and elastic modulus of 26.99 MPa, 86.89 MPa and 28.42 GPa, respectively, which also showed a high neutron shielding rate and low acid corrosion rate of 65.11% and 0.016%. The obtained results imply that the BPCs was a promising NSM for use in compact shielding design. [ABSTRACT FROM AUTHOR]

There is an urgent demand for multifunctional insulation materials with neutron shielding ability that can be particularly used in the nuclear energy system. GdBO3 ceramics are one of the candidates for such materials. In this study, GdBO3 ceramics were successfully synthesized using a simple solid‐phase method. The effect of boric acid content on the micro and macro properties of GdBO3 ceramics was explored. The experimental results indicate that the thermal conductivity of the resulting GdBO3 ceramics ranged from.12 to.68 W/(m⋅K), and lower thermal conductivity was achieved with smaller pore size and higher apparent porosity of the sintered product. Moreover, the mechanical properties of the samples in multiple temperature ranges can be improved by increasing boric acid content. Finally, neutron shielding permeability study, performed on the samples in different thicknesses, reveal that GdBO3 ceramics possessed excellent neutron shielding performance (NSP). The obtained results manifest that GdBO3 ceramics with outstanding heat insulation and NSP have a potential application in a nuclear reactor. [ABSTRACT FROM AUTHOR]

Fast neutron detection is significant for neutron imaging and flux monitoring but cannot be directly achieved by inorganic semiconductors. The traditional detection is mainly mediated by an organic scintillator and a coupled photodetector, resulting in signal losses. Here, a direct detection method for fast neutrons is demonstrated based on organic semiconducting single crystals (OSSCs) detectors. Methyl 4‐hydroxybenzoate (4MHB, C6H5O‐COOCH3) and 4‐hydroxycyanobenzene (4HCB, C6H5O‐CN). The organic semiconductor acts as a fast neutron sensitive material due to its high hydrogen density, simultaneously as a semiconductor that generates the electric signal. The detectors based on 4MHB crystals can quantitatively measure the dose and energy of the fast neutron flux with a response time of 0.5 µs and detection efficiency of 78.5% cm−3. Effects of functional groups on fast neutron detection performances are also investigated as a guideline to synthesis new molecules for this purpose. Furthermore, neutron radiation effects on these detectors are investigated. Hydrogen‐related point defects are generated by fast neutrons, but device performances remain robust after irradiation of 1013 n cm−2 fast neutrons. This study demonstrates that OSSCs show great potential as direct fast neutron detectors and particularly have highly‐localized and tissue‐equivalent properties that benefit neutron imaging and cancer therapy applications. [ABSTRACT FROM AUTHOR]

An inelastic neutron scattering system was developed to determine the elemental composition of large metallic materials. The geometrical size of the system was optimized by using Monte Carlo simulation. An experimental setup consisted of a DT neutron generator and a HPGe detector was built based on the optimized configuration and applied to analyze titanium samples. The net peak areas of titanium versus sample mass showed a linear dependence and the mass detection limit was 64 g. The prompt gamma spectra were compared to simulation data. The results demonstrated a good agreement for the signal-to-background ratio of titanium peak between measurements and simulations. [ABSTRACT FROM AUTHOR]

Elemental imaging plays an important role in characterizing the chemical and physical properties of large samples. In this work, a position-sensitive technique using prompt gamma ray neutron activation analysis (PGNAA) was applied to image the internal composition of large samples with 10–20 cm thicknesses. An inelastic neutron scattering system consisting of a D-T neutron generator and a high-purity germanium (HPGe) detector was built and used for elemental distribution analysis of a large metal sample containing iron, titanium, and copper. The 2D elemental imaging of the three elements was performed using the designed system. The effect of inhomogeneous neutron field was also corrected using Monte Carlo simulations. The results indicate that ~4 cm spatial resolution can be achieved. The position-sensitive elemental analysis based on inelastic neutron scattering reaction is efficient for bulk metal sample analysis. [ABSTRACT FROM AUTHOR]

Environment‐oriented low‐cost Al2O3 reticulated porous ceramics with hierarchical pore structure were fabricated by the polymer sponge replica method combined with vacuum infiltration methods, using Al2O3 powders and SiC solid waste (SCSW) as raw material and a pore‐forming agent. The effects of SCSW addition amount on mechanical properties, microstructure and pore size of Ceramics were investigated. The results showed that the thermal shock resistance of specimens increased gradually with addition of SCSW, however, the median pore diameter increased firstly and then decreased, due to the generation of mullite and liquid phase. After calcination, the residual stress was generated within the coating layer because of the difference in the thermal expansion coefficients of ceramic matrix and coating layer, which could improve the properties of Ceramics by deflecting and bifurcating crack growth path. The results showed that the best dosage of SCSW was 30 wt%. [ABSTRACT FROM AUTHOR]

In terms of improving the alkali corrosion resistance of corundum castables, coating technology is applied to preparing the excellent properties of corundum castables with a glaze layer. The work focuses on the effect of the ratio of Al2O3/SiO2 on the properties of Li2O-Al2O3-SiO2 glazes. Furthermore, the influence of Li2O-Al2O3-SiO2 glazes on the alkali corrosion resistance of corundum castables is investigated. The results show that at a high temperature with increasing of the ratio of SiO2/Al2O3 in Li2O-Al2O3-SiO2 glazes, the viscosity and amount of liquid phase in the glaze increase gradually, which has a great influence on the quality of the glaze at a high temperature. And as the ratio of Al2O3/SiO2 in the glaze is between 6 and 8, the apparent porosity of corundum castables with the glaze layer decreases significantly resulting in preventing the permeation of alkali vapor into the castables, which can improve the alkali corrosion resistance and mechanical properties of corundum castables dramatically. Moreover, as the thermal expansion coefficient of the matrix is higher than the glaze layer, the compressive residual stress (tangential direction) will exist in the glaze layer, resulting in enhancing crack bifurcation, which is beneficial to improving the properties of corundum castables. [ABSTRACT FROM AUTHOR]

Emission intensity plays an important role in laser–induced breakdown spectroscopy. A new sample preparation method is proposed to enhance the emission intensity for determining metallic elements. A layer of epoxy resin film is cured on the surface of a metal sheet sample, and a laser beam is used to ablate the film and form a circular hole through it. Results show that by using the proposed method, the emission intensity for Al, Cr, Cu, Fe and W increases by 66.7%–699.6%, and the relative standard deviation (RSD) decreases from 6.5%–25.5% to 0.2%–12.9%. This suggests that emission lines with high intensity and low RSD can be obtained using the proposed method. This convenient and low–cost method has the potential for improving the quantification and imaging performance of bulk samples. [Display omitted] • A new method is proposed to improve the analysis performance for LIBS. • The spectral intensity of Al, Cr, Cu, Fe and W were enhanced by at least 60%. • The RSDs for Al, Cr, Cu, Fe and W were decreases from 6.5%–25.5% to 0.2%–12.9%. [ABSTRACT FROM AUTHOR]

Time-encoded imaging could be useful for searching potential radioactive sources for preventing illicit transportation and trafficking of nuclear materials. A 2-D, dual-particle, time-encoded imager was developed for gamma-ray and neutron source imaging. The influence of central detector and coded mask rotation speed to imaging performance, such as angular resolution, signal-to-noise ratio and detection time, was investigated by Am–Be neutron source imaging experiments. The EJ276 plastic scintillator (Size: Φ5.08 cm × 5.08 cm) and CLYC scintillator (Size: Φ2.54 cm × 2.54 cm) couple to photomultiplier tubes was set as the central detector, respectively. Under the experiment conditions (Am–Be neutron source; 300 mCi; 1.8 m), for the neutron and gamma-ray images with EJ276 detector, the best horizontal and vertical angular resolution was (3.7°, 4.8°) and (5.9°, 6.6°), minimum detection time was 100 s and 600 s, respectively; for the neutron and gamma-ray images with CLYC detector, the best horizontal, vertical angular resolution was (3.1°, 3.1°) and (3.5°, 3.3°), minimum detection time was 2200 s and 1600 s, respectively. For different central detector, the results showed that the smaller volume of detector, the better angular resolution; the lower detection efficiency, the longer detection time. For different rotation speed, too fast rotation speed can lead to failure to locate the source. • New coded mask design approach simplifies machining processes. • Batch Monte Carlo simulations help to obtain response functions efficiently. • Smaller detector size can improve spatial resolution but increases detection time. • Too fast rotation speed of coded mask can lead to failure to locate the radioactive sources. [ABSTRACT FROM AUTHOR]