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In this study, a series of aluminum borate ceramics (ABCs) with needle-like whiskers were obtained using a low-cost, solid-state, pressureless sintering ceramic route, without any additives during the preparation process. The effects of different alumina/boric acid molar ratios and sintering temperatures on the phase composition, microstructure, mechanical properties, specific surface area, pore size distribution, and sub-cadmium neutron shielding properties of ABCs were studied using orthogonal experiments. It was observed that pure phase aluminum borate (Al18B4O33) ceramics could be obtained at 1100 ℃, forming a mass of needle-like whiskers. The whiskers' aspect ratio, fracture work, specific surface area, and pore size distribution of ABCs are maximized when ABCs are sintered at 1100 ℃ with 9:6 alumina/boric acid molar ratio. In this condition, ABCs (0.5 cm) can shield 70% of sub-cadmium neutrons (E<0.4 eV). These findings demonstrate the great potential of aluminum borate ceramics for neutron shielding applications. [ABSTRACT FROM AUTHOR]

Ionizing irradiation, as a new pretreatment method for the anaerobic fermentation of organic pollutants, is featured with fast reaction speed, good treatment effect, no need to add any chemical reagents, and no secondary pollution. This study explores the mechanism of improving anaerobic fermentation performance of rice samples pretreated by cobalt-60 gamma irradiation through the influence on fermentation substrate, acidogenic phase and methanogenic phase. The results reveal that the soluble chemical oxygen demand of the irradiated rice sample at an absorbed dose of 9.6 kGy increases by 12.4 times due to the dissolution of small molecules of fat-soluble organic matter. The yield of biogas in the acidogenic phase increases by 22.2% with a slight increase in hydrogen gas content. The yield of biogas and methane gas content in the methanogenic phase increases by 27.3% and 15%, respectively. Microbial genome analysis, performed with MiSeq high-throughput sequencing and metagenomic methods, suggests the microbial abundance and metabolic functions in the anaerobic fermentation process change significantly as a result of the pretreatment by gamma irradiation. [ABSTRACT FROM AUTHOR]

The high energy and compact size of circular electron accelerator (betatron)make it an excellent non-destructive testing tool. At a laboratory in Nanjing University of Aeronautics and Astronautics, a new betatron has been installed. In consideration of safety, the accelerator laboratory was accurately modeled, and a custom photon source was introduced and validated to accurately simulate the distribution of rays within the laboratory. Consequently, the dose rate map was generated, the high-dose zone was marked and the safety of the shielding was demonstrated. [ABSTRACT FROM AUTHOR]

In fast neutron multiplicity counting measurement, misclassification of γ signals and loss of neutrons introduce significant measurement errors. To address these problems, machine learning (ML) algorithms were employed to improve the n/γ discrimination of liquid scintillators. A dual-scintillator time-of-flight device combined with charge comparison (CC) method was used to select reliable datasets from the D-T neutron generator. Decision Tree, Random Forest, and Back-Propagation Neural Network (BPNN) were developed and compared with the CC method. The CC method and ML algorithms were validated using 137Cs sources. The results showed that the ML algorithms had effective n/γ discrimination capabilities. The BPNN exhibited the highest DERγ (1.26%) and DERn (1.64%) discrimination performance, which reduced neutron loss and γ misclassification. In addition, the trained BPNN was used in practical measurement. [ABSTRACT FROM AUTHOR]

The neutron moderator structure of a prompt gamma-ray neutron activation analysis (PGNAA) system based on a deuterium–tritium (DT) neutron generator was re-optimized. In this study, a 1 cm lead combined with a 2 cm high-density polyethylene (HDPE) was set as a new moderator. The thermal neutron flux, fast neutron flux of more than 6 MeV and total neutron flux in the samples increased by 22%, 41% and 41%, respectively. The signal-to-interference ratio (SIR) increased from 15 to 19%. The measurement results with samples containing different element contents indicated that the detection sensitivity of the analyzer with the new moderator structure was significantly improved. [ABSTRACT FROM AUTHOR]

Multifunctional radiation shielding materials are important for the development of miniaturised nuclear reactors. Bi6B10+2xO24+3x (x = − 2, − 1,0,1,2) compounds were economically and conveniently synthesised by using a solid-state sintering reaction of bismuth oxide and boric acid. The effects of liquid phase boron oxide migration due to sintering temperature and boric acid content on the microscopic morphology, crystalline phase composition and macroscopic properties of the samples were systematically investigated. And the studies highlight that when the content of boric acid particles increases, the nucleation and growth of bismuth borate is accelerated, which promotes the sintering of the ceramic and have a positive effect on improving the physical properties of materials. The ceramic with x = 1 exhibited the highest cold elastic modulus (28.41 GPa), cold flexural strength (18.55 MPa) and room temperature thermal conductivity (0.3420 W/(m·K)). Radiation shielding tests showed neutron and gamma shielding of 63.7% and 39% for the ceramic with x = 1 when the sample thickness was 1.5 cm. Thus, based on the information gathered from our research, Bi6B10+2xO24+3x (x = − 2, − 1,0,1,2) ceramics were expected to be designed as an integrated nuclear reactor shielding/insulation material. [ABSTRACT FROM AUTHOR]

In this research, a built-in PGNAA device for industrial analysis was initially optimized and designed. A D-T neutron generator and BGO scintillator detector were as the core, as well as the geometries of modules in the device were optimized based on the Signal-to-noise ratio optimization method in MCNP software, and the experimental device was built based on the optimized model. In addition, after the neutron self-shielding effect correction, the elemental spectra were calculated for sample analysis. Finally, the aqueous solution samples were initially set and measured both in simulation and experiment for investigation, and the elemental sensitivity was furtherly compared for discussing the performance of device. [ABSTRACT FROM AUTHOR]

In gamma ray full spectral analysis, the risk that the covariance matrix is ill-conditioned is high, especially in prompt gamma ray neutron activation analysis technology. The ill-conditioned matrix increases the sensitivity of the system to errors. To address this issue, this study offered an optimization approach that involved adding minor disturbances to the covariance matrix and determining the value of the disturbances using the particle swarm optimization algorithm. After optimization, the datasets from two verification experiments became more stable. [ABSTRACT FROM AUTHOR]

To address hidden explosive identification in luggage, a luggage detection system was designed based on PGNAA technology in this study. A multidetector structure was designed, and hardware modules were optimized based on a Signal-to-Noise-Ratio optimization method. Furthermore, a Weighted Spectra Library (WSL) method was proposed for spectral analysis. Combining the optimized device with the WSL method, the feasibility of the device for explosive detection was assessed both in MCNP simulation and by experimental measurement. Finally, the measurement performance of the device was further investigated, the minimum detectable mass of explosive was 200 g, and the minimum detection time was 60 s at 1000 g explosive based on the present system. [ABSTRACT FROM AUTHOR]

A PGNAA set-up consisting of a 241Am-Be neutron source and a HPGe detector was proposed to determine rare-earth elements in leachate during infiltration process, and was conducted to analyze samples containing gadolinium, samarium, and neodymium. A good agreement between the experimental net peak areas and the MCNP simulated ones was observed. The net peak areas of gadolinium, samarium, and neodymium versus their corresponding masses were then analyzed. The results showed linear dependences after neutron self-shielding correction, and the minimum detectable concentrations were 27.94 mg/L (Gd), 4.77 mg /L (Sm) and 1077 mg/L (Nd), respectively. [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]

In order to measure the energy spectra of secondary neutrons in proton and heavy-ion radiotherapy, a neutron spectrometer has been developed. In this paper, two organic scintillation detectors combined with photomultiplier tubes were used to form a dual-scintillator time-of-flight spectrometer. The performance of this spectrometer was tested with a DT neutron generator, and the detection efficiency of each detector as well as the spectrometer were simulated by Geant4 toolkit. It's shown that the time resolution of the spectrometer is 0.797 ns with an energy resolution of 26.4% for neutrons with an energy of 14 MeV at a flight distances over 150 cm. [ABSTRACT FROM AUTHOR]

As an excellent tool, neutron generators have been used widely in prompt gamma-ray neutron activation analysis (PGNAA) technology. In this work, a new PGNAA laboratory was proposed to equip a D–T neutron generator. For safety reasons, radiation shielding of the laboratory was designed, and its protection efficiency was validated by using MCNP simulations and experiments. The results show that the proposed shielding can meet the radiation protection set by the International Commission on Radiological Protection and the Chinese government. [ABSTRACT FROM AUTHOR]

Food waste has a high utilization value, but its high moisture content brings more disadvantages to its storage, transportation and energy utilizations. Dehydration of food waste is conducive to subsequent treatment, and herein, the effects of ionizing radiation pretreatment on the dehydration performance of tofu protein waste were examined. The mechanical centrifugation dehydration, moisture distribution, bond energy (Hb), drying time, and drying rate indicated that ionizing radiation pretreatment significantly enhanced the supernatant volume, free water content, and drying rate, while reducing Hb and drying time. Moreover, the mechanism underlying the enhanced dehydration performance was discussed based on particle size analysis, Scanning electron microscope, UV–vis spectroscopy and pH value. [ABSTRACT FROM AUTHOR]

Mullite reticulated porous ceramics (RPCs) were fabricated with fly ash, alumina, and andalusite by polymer sponge replica technique, followed by the process of vacuum infiltration with recoating slurry included. And the effect of different recoating slurry with different particle size fly ash on the properties of mullite RPCs was studied. The matrix slurry and recoating slurry were investigated and optimized. And then, the microstructure, composition of phases, and mechanical properties of mullite RPCs were examined by SEM (scanning electron micrograph), XRD (X-ray diffraction), and hydraulic universal testing machine. Moreover, the influence of particle size of fly ash on the thermal shock stability was analyzed by calculating residual stress model and grey relational model. The result indicated that the specimens that were recoated by the slurry with the smaller particle size of fly ash might have more excellent properties. [ABSTRACT FROM AUTHOR]

The effects of different dose rates on the degradation of 2,6-dichlorophenol (2,6-DCP) in aqueous solution were investigated at about 2 × 104 Gy absorbed dose, using a 10 MeV electron beam accelerator. It was found that the removal efficiency decreased with increasing dose rate at all initial concentrations of 0.5, 1 and 2 g L−1, and the effect was significantly diminished by addition of P25 TiO2 nanoparticles. Alkaline medium were unfavorable for degradation of 2,6-DCP. Hydrogen peroxide (H2O2) could promote the removal efficiency at a lower dose rate rather than at a higher one. [ABSTRACT FROM AUTHOR]

In the present study, the explosion-proof detection integrated system (EPDS) is designed for social security. With the D-T neutron generator and BGO detector as the core components, the hardware modules in EPDS are optimized based on SNR evaluation in MCNP simulation. With the 50 MPa load on the internal surface in ANSYS software, the small deformation of wall (6.0354 mm) shows the good explosion-proof performance of EPDS. Furthermore, 6 kinds of explosives with 5 ordinary goods are measured, and the results shows the good resolution capability based on the element ratio method. Finally, with the investigation of detection results under different time gradient, the minimum detection time is discussed as 600 s. [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]

In the present study, the multi-detectors device was designed for landmine detection based on the MCNP simulation. With the D-T neutron generator and BGO detectors set as the core of device, boron-doping polyethylene with 5% boron was chosen for decreasing the activated noise in device. Based on the designed device, the method was proposed to detect the accurate position of buried landmine by discussing the relationship of nitrogen response between different detectors. With the calculation of simulation results, it indicated the accurate position of landmine could be acquired with a small deviation according the method. Finally, based on the established device, experimental measurement was made for furtherly investigating the validity of method. [ABSTRACT FROM AUTHOR]

In the present study, the coal on-line analysis system is optimized, and the signal-to-noise ratio (SNR) is quantified and set as the evaluation criterion for device optimization. 3 cm lead with 3 cm polyethylene is set as moderator, and 13 cm lead is for a better shielding. Besides, the neutron generator is set at the center of device, and 72 cm is set as the better distance of axis between neutron generator and detector. Finally, by comparing with the previous experimental results, the Mean Absolute Percentage Error of element with the value less than 1% is improved after device optimization by SNR evaluation. [ABSTRACT FROM AUTHOR]

Degradation mechanism of p-cresol in aqueous solutions by gamma-ray irradiation was investigated at various initial p-cresol concentrations with different absorbed doses. The results show that p-cresol in aqueous solutions can effectively be degraded by gamma-ray irradiation. Chemical oxygen demand was used to assess the degree of mineralization of p-cresol. The degradation can be enhanced by the additions of free Radical Scavengers. The degradation products were identified by high-performance liquid chromatography with tandem mass spectrometric. Degradation mechanism of p-cresol in aqueous solutions were proposed according to the products analysis. [ABSTRACT FROM AUTHOR]

Hexavalent chromium is a type of toxic chemical, it may cause allergies, hereditary genetic defects and cancer in humans by inhalation, and it is also a persistent danger to the environment. However, chromium metal, trivalent chromium and tetravalent chromium have low toxicities. In this study, semiconductor materials (quartz fibre and TiO) were added to a hexavalent chromium solution and the removal efficiency of hexavalent chromium as a function of the γ-ray irradiation dose, as well as the catalytic mechanism, was investigated. It was observed that the reduction of hexavalent chromium by γ-ray irradiation was largely promoted in the presence of semiconductor materials; the semiconductor materials act as catalysts under the gamma-ray irradiation. The hexavalent chromium in the solution can be converted to an insoluble precipitate by gamma-ray irradiation. These results are highly beneficial to apply semiconductor materials as catalysts for the removal of contaminants by radiation. [ABSTRACT FROM AUTHOR]

In order to solve the background influence of cadmium detection in saline water using prompt gamma neutron activation analysis (PGNAA) technique, a series experiments have been designed and carried out. Furthermore, a method based on internal standard was used to correct the neutron self-shielding effect, and the background influence has been decreased sequentially. The results showed a good linear relationship between the characteristic peak counts and the concentrations of cadmium after the neutron self-shielding correction. And in the detection of saline water by PGNAA technique, the proposed methodology can be used to reduce the influence of background with the self-shielding effect correction. [ABSTRACT FROM AUTHOR]

A method based on internal standard is proposed to correct the thermal neutron self-shielding effect of aqueous samples containing elements with large thermal neutron absorption cross-section using prompt gamma-ray neutron activation analysis. The experiments for determination of boron and cadmium dissolved in water were carried out to validate the method using a setup with a 300 mCi Am-Be source and a cylindrical 4 × 4 inch (diameter × height) BGO detector. The results showed the proposed methodology can be used to correct the self-shielding effects for the aqueous samples by prompt gamma neutron activation analysis. [ABSTRACT FROM AUTHOR]

The development of nuclear power releases large amounts of radionuclides into the natural environment. Herein, the sorption of radionuclide Ni on bentonite from Gaomiaozi county (Inner Mongolia, China) at different experimental conditions such as pH, contact time, ionic strength, foreign cations and anions, and temperatures were investigated by using batch technique. The results indicated that the sorption of Ni on the bentonite was quickly at first contact time and then increased slowly with increasing contact time. The sorption of Ni was strongly dependent on ionic strength at low pH values and independent of ionic strength at high pH values. The sorption of Ni on bentonite was mainly dominated by outer-sphere surface complexation or ion exchange at low pH values, whereas inner-sphere surface complexation was the main sorption mechanism at high pH values. The Langmuir, Freundlich, and D-R models were applied to simulate the sorption isotherms of Ni at three different temperatures, and the thermodynamic parameters (i.e., Δ H°, Δ S° and Δ G°) calculated from the temperature-dependent sorption isotherms indicated that the sorption of Ni on bentonite was an endothermic and spontaneous process. Experimental results indicate that the bentonite is a suitable material for the preconcentration and solidification of Ni from large volume of solutions in radionickel pollution cleanup. [ABSTRACT FROM AUTHOR]

A prompt gamma neutron activation analysis (PGNAA) set-up was developed for the elements detection in aqueous solution, which includes a 241Am-Be neutron source and a 4-inch BGO detector. The geometry of set-up is determined by a series of simulations with the MOCA code to improve the efficiency of the elements detection. The thermal neutron flux and the gammaray self-absorption are considered during the optimization calculations. Experiments were performed to validate the set-up using samples including chlorine and mercury, respectively. The result shows that the characteristic peak count has linear relationship with the chlorine and mercury concentration changing. The minimum detectable concentrations of chlorine and mercury were found as 54 mg/L and 51.4 mg/L, respectively. [ABSTRACT FROM AUTHOR]

When X-ray fluorescence (XRF) technology is used to measure the sulfur concentration in coal online, the measurement accuracy is affected by the coal's uneven surface and the particle size. In order to improve the accuracy of sulfur concentration measurement, an online measurement system, consisting of a portable X-ray fluorescence instrument and an auxiliary distance correction module, was developed in this paper. By measuring the standard coal samples of known sulfur concentration, we obtained a calibration curve that can be used to analyze the sulfur concentration. We studied the relationship between the X-ray fluorescence intensity ( I) and the distance ( D) from surfaces to instrument. The results showed that there was a good linear relationship between I and D when the sulfur content was certain. Based on these knowledge, the distance correction formula of X-ray fluorescence intensity was proposed. By applying the distance correction formula to experimental sulfur concentration measurement, we demonstrated that the measurement accuracy can be significantly increased. [ABSTRACT FROM AUTHOR]

In Fast Neutron Multiplicity Counting (FNMC), neutron cross-talk caused by elastic scattering between two or more detectors is unavoidable, posing a critical challenge to the accuracy of FNMC. This study focuses on an FNMC apparatus composed of liquid scintillator detectors, investigating the impact of polyethylene neutron scattering structures on first- and second-order cross-talk rates. By analyzing the position and energy distribution of neutrons scattered within detectors and incident onto adjacent detectors, targeted polyethylene structures were designed to minimize crosstalk rates within the system. Calculations were conducted on shielding structures of various sizes and positions to achieve optimal neutron crosstalk suppression under specific detector layout conditions. Experimental validation confirmed the reliability of Geant4 simulation results and the effectiveness of the polyethylene shielding structures. Through simulations conducted on a 1 × 8 detector system composed of 3-inch EJ-301 liquid scintillator detectors, it was found that the implementation of shielding structures significantly reduced cross-talk rates across all orders. [ABSTRACT FROM AUTHOR]