Generally, non-destructive testing methods based on the fast neutron technology, such as the associated alpha particle detection technology, can detect hidden hazardous materials without affecting the detected object. The effective neutrons are labeled by recoil alpha particles produced in a D-T reaction, which can significantly improve the signal-to-noise ratio of neutron detection. Meanwhile, the spatial information of the detected object can be obtained based on the spatial resolution of alpha particles. Therefore, neutron detection methods based on accompanying alpha particles have important application prospects in the field of security inspection. The principle and system composition of the neutron detection method based on associated alpha particles are briefly introduced herein. Then, key components of the detection system, such as the neutron tube, alpha particle detector, and gamma detector, are described. Next, the associated alpha particle neutron detection system, which is being studied worldwide, and its progress are presented. Finally, the prospects of this detection method are discussed.

BackgroundThe high-precision magnetoelectric velocity sensor can measure the vibration of the superconducting cavity in a low-temperature environment.PurposeThis study aims to quantitatively investigate the effects of temperature on the vibration characteristics of a superconducting cavity and provide recommendations for designing mechanical and cryogenic systems cryomodule.MethodsThe superconducting cavity in a 1.3 GHz cryomodule of the Shanghai HIgh repetitioN rate XFEL and Extreme light facility (SHINE) was taken as research object. The mechanical vibration in frequency range of 1~100 Hz, with a direction perpendicular to the beam direction was concerned, and six vibration sensors were arranged at two measuring points to monitor the velocity signals of different components. Subsequently, the displacement power spectral density, displacement root mean square, and frequency response function of superconducting cavity at the temperature of 300.0 K, 125.0 K, and 2.0 K were quantitatively analyzed using the spectrum analysis method.ResultsVibrations of the superconducting cavity caused by the flow at 2.0 K is 9.4% and 4.5% in the vertical and transverse directions, respectively, of that caused by ground source at the Shanghai Synchrotron Radiation Facility. In a cryogenic environment, the new vibration source is the cold flow, and the different fluid states have different effects on the vibration of the superconducting cavity in the vertical and lateral directions.ConclusionsThe study is valuable for guiding the tests and optimal design of cryomodules. The vibration of superconducting cavities at low temperatures can be measured using high-precision magnetoelectric velocity sensors. It is necessary to measure and analyze the potential source and its impact to satisfy the sub-micron beam stability requirements of superconducting linac and suppress the cavity frequency shift caused by mechanical vibration.

BackgroundThe beam measurement group of Shanghai Synchrotron Radiation Facility (SSRF) has developed a new software package, HOTCAP, for high-speed oscilloscope-based three-dimensional bunch charge and position measurements to investigate the transient process of injection and beam instability in a high-energy electron storage ring. However, the software package does not specifically optimize the algorithm efficiency for data-processing speed.PurposeThis study aims to optimize real-time performance of the HOTCAP software so that the time required to complete the processing and analysis of single-measurement data fully satisfies the requirements of real-time measurements.MethodsAn operational efficiency test and algorithm optimization were conducted for each functional module of the HOTCAP software package to improve the overall performance. The specific time consumption data of each module in the processing flow were calculated, and the most time-consuming algorithm for extracting the three-dimensional position of charges was specially optimized to reduce duplicate calculations by using cached variables.ResultsAfter optimization, the processing time of the single-measurement data is reduced by more than 10 times.ConclusionsThe optimized HOTCAP software by this study satisfies the real-time monitoring and online data release requirements of the high-energy electron storage ring status.

BackgroundWhen conducting experiments at a synchrotron radiation facility, it is necessary to scan the position of the sample or the beam energy within a certain range. The scanning modes are categorized as step scanning and on-the-fly. In the step-scanning mode, there is a significant amount of dead time in the motion mechanism, which leads to long data acquisition times and low experimental efficiency. By contrast, the on-the-fly mode allows for continuous motion while triggering the detectors and sensors, avoiding the dead time of the motion mechanism and greatly improving the efficiency of the experiments.PurposeThis study aims to propose and implement a hardware-triggered on-the-fly system to achieve rapid and continuous scanning during experimental processes for Hefei light source (HLS).MethodsThe proposed on-the-fly system mainly consisted of a synchronous signal acquisition module, a synchronous motion control module, and a software control module. The design of the hardware synchronous trigger module in the synchronous signal acquisition module was based on the field-programmable gate array (FPGA) development board Zynq7020. The encoder signals were decoded into position signals and used to trigger other devices based on position or time. This made it the central component for the on-the-fly mode. The design of the synchronous motion control module was based on a highly synchronous EtherCAT bus. The motion controller supported multi-axis coordination and programmable trajectory motion to meet the requirements of different experiments. The software control module utilized the experimental physics and industrial control system (EPICS) architecture for device control, and experiment flow control and data acquisition were implemented using Bluesky platform. Finally, the proposed on-the-fly system has been deployed and tested at the Soft X-ray Magnetic Circular Dichroism (XMCD) experimental station of HLS.ResultsThe experimental results demonstrate that the on-the-fly mode system not only meets the spectral performance requirements, but also reduces the single acquisition time from tens of minutes in the step-scanning mode to approximately 1 min.ConclusionsTherefore, the on-the-fly system designed and implemented in this study significantly improves the experimental efficiency and user experience.

BackgroundSextupoles are an important component of storage ring octonal unit in high energy synchrotron radiation sources. They require complex technological processes and precise center extraction. Therefore, it is necessary to find out the most reasonable calibration scheme for the mechanical center.PurposeThis study aims at the calibration scheme for the mechanical center extraction of high energy photon Ssurce (HEPS) sextupoles, and obtaining the corrected mechanical central coordinate system.MethodsThe method of directly measuring the reference plane of the sextupole was adopted for the mechanical center calibration of magnets. By rotating the conventional calibration coordinate system with a given pole seam deviation angle, the three polar seam surfaces were brought closer to the theoretical positions to decrease the main diagonal component of the sextupoles. The mechanical center calibrations were performed twice for each hexacode iron to further reduce the impact of the polar seam error.ResultsThe calibration results show that the calibration repeat accuracy is 0.005 mm for the sextupole. The standard deviation between the measured value and the design value of the pole seam spacing is 0.015 mm. Additionally, the standard deviation of the reference point before and after the rotation of the coordinate system is 0.09 mm, with a maximum rotation angle of 0.6 mrad.ConclusionsThe calibration scheme of this study can be used to improve the calibration accuracy and provide reference for the calibration of similar equipment. It ensures smooth installation of accelerator devices and is of significant importance for accelerator collimation measurements.

BackgroundAccurately quantifying the uranium in uranium yellow cake material is the key to selecting the subsequent processing technology. As an essential nondestructive testing method for uranium-containing materials, the active multiplicity method is proposed to quantify uranium by recording and analyzing 238U fission information induced by neutron sources. However, the quantitative results are biased owing to the neutron self-shielding of the uranium yellow cake material itself and differences in water content between samples.PurposeThis study aims to rapidly measure the uranium content of uranium yellow cake material using active multiplicity method and further improve of measurement accuracy.MethodsFirst of all, following the comparison of the excitation effects of different neutron sources on a sample using the MCNP (Monte Carlo N-Particle Transport) program, a 241Am-Be source was selected to simulate the sample measurement process and optimized using MATLAB programming combined with MCNP. Then, the curve of multiplication factor M versus the uranium mass was obtained by simulation, and an appropriate M was selected according to the net content of the sample. Finally, the quantitative error caused by the difference between neutron absorption and water content in the process was investigated, and the double rate was corrected using the relationship between S0/Si and D0/Di and then calculated.ResultsThe simulation results of a series of samples with different masses and water contents show that a large gap is found between M and the leakage multiplication factor ML caused by neutron self-shielding. The error in uranium quantification is less than 5%; neutron self-shielding due to the change in water content affects the single, double, and triple counting rates (S/D/T). The relative error of uranium quantification can be controlled at around 10%.ConclusionsThis study has significance and important reference value for further research on the application of the active multiplicity method in the production and measurement of uranium yellow cake.

BackgroundIonizing radiation can cause damage to animal's intestinal tissue. Citrulline is produced in the intestinal epithelial cell and has been proven to possess a protective effect on the gastrointestinal tract.PurposeThis study aims to investigate the protective effects and the underlying mechanisms of citrulline in the context of radiation-induced intestinal injuries.MethodsFirstly, a mouse model of an acute radiation-induced intestinal injury was established, incorporating a normal control, a simple irradiation, and an irradiation plus citrulline group. Then, these groups were employed to scrutinize the protective effects and mechanisms associated with citrulline. Subsequently, hematoxylin-eosin staining was used to examine the morphology of the mice's intestinal tissue, and the Elisa kit was employed to quantify endotoxin levels in plasma, as well as nitric oxide and inducible nitric oxide synthase in the intestinal tissue. Finally, focal adhesion kinase and Occludin levels in the intestinal tissue were assessed using western blotting.ResultsThe experimental results demonstrate that intraperitoneal injection of 1 g?kg-1?d-1 citrulline for one week following irradiation significantly extend the median survival time of irradiated mice and increase their body weight. Moreover, it markedly reduces plasma endotoxin levels, elevate the expression levels of focal adhesion kinase (FAK) and intestinal tight junction protein (Occludin), and decreases the expression levels of nitric oxide (NO) and inducible nitric oxide synthase (iNOS) in the intestinal tissue.ConclusionsCitrulline enhances the integrity of the intestinal barrier in irradiated mice, improves barrier function, mitigates nitrosative stress, and demonstrates a protective impact on radiation-induced intestinal damage in mice.

BackgroundThe very small-angle neutron scattering (VSANS) spectrometer is currently being constructed at the China spallation neutron source (CSNS). The neutron detector plays a key role in meeting the detection requirements of the spectrometer.PurposeThis study aims to achieve accurate measurement of neutron diffraction in the small angle scattering mode which requires the position resolution of the neutron detector to be ≤2 mm, and the detection efficiency to be ≥60%@0.4 nm.MethodsA large-area position-sensitive neutron scintillator detector mainly composed of 6LiF/ZnS(Ag) scintillation screen, wavelength shift fiber (WLSF), and a silicon photomultiplier (SiPM) was designed and developed to achieve high efficiency and high-resolution real-time detection of thermal neutrons. The optical transmission performance of the 0.5-mm-diameter wavelength shift fiber was investigated in detail. The gain and the thermal noise characteristics of various SiPMs were examined. Finally, a 300 mm×300 mm engineering prototype of the detector was developed and tested by experiments. The detection efficiency was calculated with comparison of the incident neutron counts of the stander 3He tube whilst the detector's position resolution was tested using a boron-doped aluminum plate with a narrow slit bearing the label 'CSNS'.ResultsThe neutron beam test results show that the position resolution of the detector is 1.2 mm×1.2 mm and that the neutron detection efficiency is (61.8±0.2)%@0.4 nm.ConclusionsThe high-resolution neutron scintillator detector developed in this study satisfies the engineering design target, and meets the neutron scintillator detector meets the neutron diffraction measurement needs for the VSANS spectrometer of the CSNS.

BackgroundEffective measurement using dual Geiger-Müller (GM) counter tubes hinges on the range switch control technology. This technology facilitates the selection of the appropriate counter tube for measurement. Nonetheless, the performance disparities between the two types of GM counter tubes imply that the conventional method of bifurcating the measurement range into two sections results in reduced linearity for the overlapping measurement ranges.PurposeThis study aims to propose a new control method for range switching to enhance the linearity of the overlapping ranges in the measurement using dual GM counter tubes.MethodsA dual GM counter detector was consisted of a low range GM counter tube with measurement range of 0.1 μ Sv· h-1~10 mSv·h-1, and a high range GM counter tube with measurement range of 1 mSv·h-1~100 Sv·h-1. The measurement range of 0.1 μSv·h-1~100 Sv·h-1 was segmented into three categories: low, medium, and high. Rapid and automatic transitions between these three ranges were facilitated by high-voltage control circuit, measurement range control circuit and dead time regulation circuit. During the medium range of 1~10 mSv·h-1 measurement, two range switching threshold points were set within the overlapping area, and data from the two GM counters were weighting processed respectively in the single-chip processor, hence appropriate weighting factors that maximize the linear fit of the measurement results of the dual GM counter were obtained. Finally, the 241Am source and 60Co ource were employed to test the dual GM counter detector circuits.ResultsPreliminary test results indicate that the proposed dual GM counter detector facilitates fast automatic transitions among the three measurement ranges, and the linear fit of the counter tube in the overlapping area from 1 000 μGy·h-1 to 10 000 μGy·h-1 is enhanced, making the linear fit of the dual GM counter reach up to 0.999 1 within the measurement range of 251~25 130 μGy·h-1.ConclusionsThe overall measurement linearity of the dual GM counter is effectively improved by proposed control method of this study for range switching.

BackgroundThe total dose effect of ionization on satellites in Geostationary Earth Orbit (GEO) is caused by space particle radiation in GEO.PurposeThis study aims to combine high-performance cerium-doped yttrium-lutetium silicate (LYSO:Ce) crystals with an aluminum layer to shield the effect of proton irradiation for effective electron radiation dose detection.MethodsFirstly, the detector model was established using Geant4, the shielding effects of different materials for LYSO:Ce detector were compared. Then, the response characteristics of the detector were analyzed, and the factors affecting the output response of the detector at different shielding layer thicknesses were investigated.ResultsThe results showed that the effect of proton irradiation can be eliminated by using 0.022 mm aluminum as the shielding layer. The LYSO:Ce crystal-based detector has a good linear response, and the secondary electrons and photons generated when electrons pass through the shield improve the response sensitivity of the detector. The ionization stopping power of the electron is approximately inversely proportional to the square of the incident electron velocity, and the detector response to radiation is enhanced when the transmission distance between the electron and the detector was appropriately increased. The highest electron detection efficiency of the detector occurs in the energy range of 0.04~1 MeV.ConclusionsThis study on the characteristics of electron radiation dose detector on the basis of LYSO:Ce crystals combined with an aluminum layer provides a technical reference and theoretical support for designing new scintillator space radiation detectors.

BackgroundA megawatt-class nuclear power system has been developed by coupling a heat pipe reactor with a supercritical carbon dioxide (S-CO2) Brayton cycle. This system offers advantages in terms of high safety, power density, and compactness.PurposeThis study aims at the operation characteristics of this power system with high efficiency and compactness.MethodsThe coupling code of a self-developed heat pipe reactor transient analysis code, Transient Analysis code for heat Pipe and AMTEC power conversion space Reactor power System (TAPIRS), and supercritical carbon dioxide Brayton cycle transient analysis code (SCTRAN/CO2) were utilized to analyze the open-loop dynamic characteristics under conditions of reactivity disturbance, load disturbance, cooling water temperature disturbance, and cooling water mass flowrate disturbance. Then, the control system was designed. On this basis, three load variation operation conditions, i.e., linear load variation, stepped load variation, and load rejection, were simulated and analyzed.ResultsThe simulation results show that the rotational speed of the new nuclear power system is sensitive to the disturbances and needs to be controlled. The bypass flowrate increases under low load conditions, hence the flowrate of the compressor needs to be controlled as well. The system can adjust the load from 0% to 100% at a rate of 6% FP (full power)·min-1. It is capable of implementing stepped load changes, although it experiences slightly more pronounced fluctuations. Under load rejection conditions, the stabilization time might be prolonged, but it will eventually stabilize with all parameters remaining within safe limits.ConclusionsThis study provides a reference for the conceptual design of new nuclear power systems with high efficiency and compactness.

BackgroundThe direct simulation of the γ radiation field in a large space has a very low calculation efficiency.PurposeThis study aims to apply the global variance reduction (GVR) method to the calculation of the γ radiation field in a large space.MethodsFirstly, the volume correction factor was introduced for modifying the lower limit of the weight window wth to address the over-splitting problem caused by the volume difference between the counting cells/grids. The global quality factor (FOMG factor) calculated by the flux-based GVR method using the volume correction was 39 times higher than that obtained by direct simulation. Then, a non-counting area correction method was proposed to address the time-consuming problem encountered in non-counting area calculation while the FOMG factor was further improved by 40%. Finally, based on both the volume correction and non-counting area correction, the calculation of the γ radiation field were compared with that of seven GVR methods based on the particle error, weight, track, number, energy, collision and flux, respectively. The smoothing factor SI was introduced into the flux-based GVR method for results further analysis. [Results and Conclusions] The results show that the FOMG factor calculated by the seven GVR methods is about 2~3 orders of magnitude higher than that obtained by direct simulation, and the standard deviation σ is reduced by 2~3 orders of magnitude. The FOMG factor calculated by the weight-based GVR method is 2 304 times higher than that obtained by direct simulation; this value yields the best variance reduction effect among all GVR methods. As SI increases, the lower limit of the weight window wth of the simulation decreases, and the FOMG factor first increases and then decreases. When SI=0.8, the calculated FOMG factor has the largest value, which is 3 246 times higher than that obtained by direct simulation.

BackgroundWith the continuous development of society and economy, nuclear energy has emerged as a crucial solution to address global energy shortages. However, uranium reserves on land have diminished after nearly half a century of extraction, resulting in irreversible harm to the natural environment. Consequently, seawater uranium extraction has become a more eco-friendly and abundant source of uranium resources, compared to terrestrial uranium mining. And extracting uranium from seawater emerges as a prudent strategy.PurposeThis study aims to use kinetic chromatography to extract uranium from seawater and investigate the separation mechanism.MethodsLeveraging the concepts of dynamic chromatography, a pulsed-injection energy-endowed kinetic chromatography column was developed. The column utilized spherical SiO2 with a diameter of 0.2 mm and a length of 5 m as the filler. After filling, it encompassed approximately 30 600 chromatographic separation units. A peristaltic pump for pulse injection was applied to the kinetic chromatography system, and a switching pulse injection device was equipped to enable time control splitting. Subsequently, a self-developed on-line spectrophotometric detector was utilized to monitor the concentration of target components in the solution in real-time so as to avoid human control errors during multistage separation experiments. Additionally, the behavior of uranyl ions in kinetic chromatography under varying conditions and determine the best separation conditions was investigated by experiments using different mobile phase carriers, pH values, injection flow rates, energy-endowed modes, and energy-endowed series, and various energy-endowed methods, including water bath heating, ultrasonic, and external magnetic fields, were employed to achieve optimal separation conditions. Finally, the separation factor of uranium and sodium ions in actual seawater uranium extraction was calculated to explore the separation mechanism by separate studies of uranium, europium, and sodium ions, as well as an actual seawater uranium extraction.ResultResults of this series of studies demonstrates that the best separation effect is achieved when using hydrochloric acid as the mobile phase carrier in dynamic chromatography, with a pH of 2, a sample flow rate of 4.109 mL·min-1, water bath heating as the energy-endowed mode, a heating temperature of 50 ℃, and a heating series of 4. Under these optimal conditions, the separation factor between uranium and sodium ions can reach 1.1854 in the separation studies of uranium, europium and sodium ions. In the real seawater uranium extraction study, the separation factor between uranium and sodium ions can reach 1.575. After simulation and calculation, the theoretical separation of uranium and sodium ions in seawater requires a minimum of 20 levels.ConclusionsThe efficient and rapid extraction and separation of uranium from seawater is facilitated in this study using a pulsed-injection energy-endowed kinetic chromatography column. This separation strategy allows for the efficient separation of light and heavy particles without interaction of the mobile and stationary, resulting in a high sample recovery rate and no need for column regeneration. This technique has potential for the separation of other nuclides, making it a versatile tool for nuclear chemistry research.

BackgroundHigh-order harmonics of neutron diffusion equations can be used to reconstruct the neutron flux distribution in a reactor core, but traditional source iteration methods or modified source iteration methods have low solving efficiency.PurposeThis study aims to provide a reliable and efficient method for reconstructing the neutron flux distribution in reactor cores.MethodsFirstly, the neutron diffusion equation was discretized using the finite difference method. Then, the implicitly restarted Arnoldi method (IRAM) was employed to solve the eigenvalue problem of the neutron diffusion equation and obtain high-order harmonic samples for different macroscopic cross-section states. Subsequently, a low-order model for the neutron diffusion equation was constructed by using these samples and a combination of proper orthogonal decomposition (POD) and Galerkin projection, and an error model was developed to characterize the accuracy of eigenvalue and harmonic calculations. Finally, relevant programs were developed to reconstruct the neutron flux distribution in the two-dimensional steady-state TWIGL benchmark problem and validate the accuracy of the model.ResultsThe computation results show that the IRAM exhibits high accuracy in solving the high-order eigenvalues and harmonic problems of the neutron diffusion equation, with an error on the order of 10-14. The reconstruction of the neutron flux distribution based on the POD-Galerkin low-order model also maintains a high level of accuracy. The solution error increases with the order of the eigenvalues, with an error magnitude less than or equal to 10-12. The reconstructed neutron flux distribution closely matches the reference solution in the reactor core, and the error in the effective multiplication factor is only 8.7×10-5. Additionally, the computation time for the low-order model is only 10.18% of the full-order model.ConclusionsThis study provides a reliable and efficient method for reconstructing the neutron flux distribution in reactor cores. The method can be used not only to reconstruct the steady-state neutron flux distribution but also has the potential to predict the transient neutron flux distribution, which is expected to be further expanded in future applications.

BackgroundU3Si2 is regarded as one of the most promising accident-tolerant nuclear fuels for light water reactors and is expected to replace the UO2 nuclear fuel in the future. Currently, spark plasma sintering (SPS) is an advanced technique for preparing U3Si2 pellets; however, the influence of SPS parameters on the performance of the pellets is unclear.PurposeThis study aims to investigate the effects of different sintering parameters (temperature and pressure) on the mechanical and thermal properties of the U3Si2 pellets prepared using SPS technology.MethodsThe thermal diffusivity of U3Si2 pellets was measured using a laser flash apparatus, and the thermal conductivity of the pellets was calculated. The mechanical properties of the pellets, including hardness, Young's modulus, and fracture toughness, were measured using nanoindenter. Thereafter, the influence of different sintering temperatures in the range of 1 000~1 300 ℃ and pressures in the range of 30~90 MPa on the mechanical and thermal properties of U3Si2 pellets were carefully examined.ResultsThe measurement results show that the thermal conductivity of the as-synthesized pellets increases linearly with temperature in the range 27~700 ℃. Moreover, increasing the sintering temperature and pressure improves the thermal conductivity of the U3Si2 pellets. The hardness and Young's modulus of the pellets increase with an increase in sintering temperature. They also exhibit a trend of first increasing and then stabilizing with increasing pressure, and tend to fully stabilize at 60 MPa. Moreover, the fracture toughness of the pellets decreases with the increase of sintering temperature and increases with increasing pressure.ConclusionsBased on the above results, optimized SPS parameters for the U3Si2 pellets are proposed, and this study provides a reference for the preparation of high-performance U3Si2 pellets.

BackgroundLiquid molten salt reactors that use chloride salts as fuel are characterized by the high solubility of heavy metals and a hard energy spectrum, hence are ideal for transmuting transuranic nuclides (TRU). A small modular reactor exhibits the characteristics of a modular design and construction, which is one of the future development directions for nuclear energy.PurposeThis study aims to investigate the TRU incineration characteristics of a small modular chloride fast reactor (sm-MCFR) that can be refueled online and applied to the disposal of TRU in nuclear waste produced by pressurized-water reactors.MethodsFirstly, a 50-MW sm-MCFR scheme was proposed, and its neutron properties, as well as the performance of TRU incineration, were explored using the Monca program TMCBurnup (TRITON MODEC Coupled Burnup Code), a combination of the SCALE 6.1 (Standardized Computer Analyses for Licensing Evaluation) and the high-precision point burn-up program MODEC (Molten Salt Reactor Specific DEpletion Code). Then, the analysis of critical parameters, burn-up evolution, and the transmutation efficiency of both TRU mixed with Depleted Uranium (DU) and TRU combined with 232Th were investigated, using a straightforward post-processing approach.ResultsThe findings of this study indicate that using TRU as fission fuel in the sm-MCFR requires the online addition of TRU. When the heavy metal balance is maintained, the effective multiplication factor (keff) is less than 1. Conversely, when the balance is not maintained, keff > 1, allowing continuous operation. When operating at full power for 40 years, the core's residual TRU content will be significantly higher than the initial fuel load, with 657 kg remaining for the TRU+Th mix and 725 kg for the TRU+DU mix. Notably, the sm-MCFR demonstrates efficient transmutation when TRU is added online without maintaining the heavy metal balance. Over 40 years at full power, the transmutation rates will be 41% for TRU+DU and 49% for TRU+Th, effectively reducing the production of long-lived small-actinide elements.ConclusionsThe sm-MCFR can effectively incinerate TRU and provide a feasible scheme for minimizing spent fuel.