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15 April 2021, Volume 44 Issue 4 Previous Issue   
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SYNCHROTRON RADIATION TECHNOLOGY AND APPLICATIONS
Methods study on high-resolution bunch charge measurement based on cavity monitor
Shanshan CAO,Yongbin LENG,Renxian YUAN,Longwei LAI,Jian CHEN
Nuclear Techniques. 2021, 44 (4):  40101-040101.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040101
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Background

Bunch charge is the most fundamental characteristic parameter of the particle beam. The Shanghai Soft X-ray Free Electron Laser Device Facility (SXFEL) needs to add a charge feedback loop to accurately control the bunch charge and the resolution of a real-time single bunch charge measurement is required to be better than 0.5%. At present, commonly used monitors that can realize online non-intercepting bunch charge measurement include beam current transformers, button-type or strip-type electrodes, and cavity-type probes, etc. Among them, the beam current transformer is susceptible to various electromagnetic interference, and its resolution is difficult to be improved; the button probe and the stripline probe have obvious bunch position dependence. The cavity probe has high sensitivity and high signal-to-noise ratio (SNR), position independence under paraxial conditions, thus it is very suitable for high-resolution bunch charge measurement.

Purpose

This study aims to explore the methods of high-resolution bunch charge measurement based on cavity monitors.

Methods

Based on the traditional cavity probe signal measurement system using an external local oscillator signal mixing scheme, a new dual-cavity mixing scheme with a simple system structure without local oscillator frequency synthesis was proposed. It could work independently without synchronization timing signals. Both schemes were evaluated by beam experiments in the SXFEL facility.

Results

The experimental results show that the resolution of the single-cavity external IF (intermediate frequency) mixing scheme is better than 0.07% while the resolution of the dual-cavity mixing scheme is better than 0.2%.

Conclusions

Both schemes can achieve a high-resolution bunch charge measurement and satisfy the requirements of SXFEL user facility.

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ACCELERATOR, RAY TECHNOLOGY AND APPLICATIONS
Simulation study on the performance of micro X-ray tube with diamond optical window
Yiqiang XING,Jiankun ZHAO,Weicheng LI,Yibao LIU,Wei LIU,Shuang JIANG
Nuclear Techniques. 2021, 44 (4):  40201-040201.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040201
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Background

As a hot material, diamond has been widely used in various civil and military equipment with high hardness (Mohs hardness is 10), compressive strength (greater than 1.2 GPa), excellent thermal (thermal conductivity at room temperature is 20~22 W·cm-1·K-1, thermal expansion coefficient at room temperature is only (1.1~1.3)×10-6 K-1), optical (higher transparency to X-rays) and electrical properties. Traditional optical window material beryllium is harmful to the human body and industrial hazards, its hardness, thermal conductivity and the thermal expansion coefficient are much lower than that of diamond.

Purpose

This study aims to explore the performance of micro X-ray tube with diamond optical window by simulation, obtain the best thickness of diamond for X-ray tube optical window and its shielding effect against low, medium and high energy X-ray.

Methods

The Monte Carlo method was used to calculate the effective transmission ratio, peak back ratio and transmission ratio of characteristic X rays with diamond optical window in high energy region. The X-ray tube with 50 kV tube voltage and 1.0 mA tube current was taken as an example to determine the optimal thickness of diamond.

Results

Simulation results show that the Kα characteristic X-ray effective transmittance and peak to total X-ray ratio of the silver target increase continuously with the increase of the diamond window thickness, and the optimum diamond thickness is 2.0 mm. Under the optimal thickness of 2.0 mm, the effective transmittance is 154.5%, high-energy X-ray transmittance is 74.5%, and the characteristic X-ray peak back ratio is 27.9%.

Conclusions

Diamond can be used as a substitute for beryllium optical windows and has good application prospect.

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Study of beam model of medical linear accelerator based on virtual single point source
Huijuan LI,Shengxiu JIAO,Zhongben CHEN,Xiaowei LIU
Nuclear Techniques. 2021, 44 (4):  40202-040202.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040202
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Background

The beam model of medical linac is one of the bases of dose calculation. It is of great significance to study the beam model of medical linear accelerator in clinical application of radiation dose calculation.

Purpose

This study aims to provide a virtual point source model of medical linear accelerator X-ray beam, and to discuss the applicability of the model by fitting the measured dose distribution.

Methods

The X-ray beam was divided into primary ray and scattered ray. The primary ray was modeled as an anisotropic point source whilst the scattered ray was modeled as a point source whose intensity was related to the radiation field. The model parameters were obtained by fitting the measured absorbed dose distribution in water phantom.

Results

For Varian Trilogy 6 MV linear accelerator, the dose distribution given by the fitting model is in good agreement with the measured dose distribution, and the difference between the measured value and the fitting value of the total scattering factor (SCP) is less than 1.5%. For 3 cm × 3 cm, 10 cm× 10 cm and 40 cm× 40 cm radiation fields, from 1.4 cm (maximum dose depth) to 20 cm underwater depth, the average differences between the fitting and the measured value are 1.3%, 1.3% and 1.1% respectively. The average differences between the fitting and measured values of off-axis dose in the area with off axis dose ratio (OAR) greater than 90% are 2.35%, 0.75% and 0.53% respectively at the depth of 10 cm.

Conclusions

The virtual point source model of X-ray beam can well reconstruct the absorbed dose in phantom.

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Design of real-time feedback system of dynamic current for spot scanning in medical heavy-ion facility
Haoyu JIANG,Jiang ZHAO,Zhongzu ZHOU,Dezhi WANG,Daqing GAO
Nuclear Techniques. 2021, 44 (4):  40203-040203.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040203
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Background

Spot scanning therapy is an accurate radiotherapy method in medical heavy-ion facilities. The process of spot scanning therapy is that the current of scanning power supply changes rapidly in real-time. The accuracy control of beam position depends on the repeatability of the scanning power supplies and the stability of the model parameters during spot scanning therapy. However, the amplitude of position current is small and changes rapidly, it is easy to be submerged by noise, which makes it difficult for the treatment terminal to obtain accurate scanning dynamic current remotely.

Purpose

This study aims to design and implement a real time feedback system of point scan position current for quick analysis and optimization of the accuracy and repetition of the point scanning position current for medical heavy-ion facility.

Methods

The Xilinx's new scalable processing platform Zynq-7000 SoC (System on Chip) was employed to implement this system by combining high speed Fiber-optic communication with PCIE (Peripheral Component Interface Express) serial bus technology. Both the waveform data acquisition of Direct Coupled Current Transformer (DCCT) and feedback calculation of the remote power supply output current were achieved in the platform. The position current feedback system was tested in field of Lanzhou heavy ion therapy facility.

Results

The field test results show that the system can obtain the position current data of spot scanning in real time, and the measured position current deviation is 0.106 8 A, satisyfying the design requirement of less than 0.17 A.

Conclusions

The study provides an effective technical means for the precision control and optimization of spot scanning position current.

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Application research of γ energy spectrum analysis based on improved grey wolf algorithm
Wei LIU,Jiankun ZHAO,Yibao LIU,Weicheng LI,Yiqiang XING
Nuclear Techniques. 2021, 44 (4):  40204-040204.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040204
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Background

Traditional γ energy spectrum analysis methods have the disadvantages of long time, many steps and low accuracy.

Purpose

This study aims to propose an improved gray wolf algorithm based on qualitative analysis to obtain nuclide information faster and more accurately.

Methods

The convergence factor based on the inverted S-curve was adopted in the improved gray wolf algorithm to maintain the balance between the global search and the local search of the algorithm, and solve the problem of local optimum that the original gray wolf algorithm fallen into easily. A dimension-by-dimension update strategy was introduced to improve the accuracy and efficiency of optimization. Finally, this improved gray wolf algorithm was applied to experimental test on the gamma spectra of "Soil standard source" and "Marin cup standard source".

Results

Experimental results show that the improved gray wolf algorithm has a better analysis effect on multi-nuclides mixed gamma spectra. The analysis speed is 59% faster than the original gray wolf algorithm.The analytical error of all nuclides in the soil standard source can be controlled within ±10%. The average absolute error of 8 nuclides is within 4%. Except for 226Ra and 235U in the Marin Cup standard source, the errors of other nuclides are less than 10%. The average absolute error of the 8 nuclides is within 7%.

Conclusions

The improved gray wolf algorithm provides a new method for rapid analysis of nuclides.

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NUCLEAR CHEMISTRY, RADIOCHEMISTRY, RADIOPHARMACEUTICALS AND NUCLEAR MEDICINE
Preparation of ZIF-8 loaded citric acid-coated nano-zerovalent-iron and its adsorption properties for U(VI)
Jiang HE,Fei GAO,Feng ZHANG,Feng FENG,Shilong SHI,Jun LIU
Nuclear Techniques. 2021, 44 (4):  40301-040301.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040301
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Background

The separation, removal and recovery of U(VI) from water is of great significance to the sustainable development of nuclear energy.

Purpose

This study aims to prepare a composite material ZIF-8 loaded by citric acid-coated nano-zero-valent iron (nZVI@CA/ZIF-8), and investigate its adsorption behavior and mechanism for U(VI).

Methods

nZVI@CA/ZIF-8 was chemically synthesized and its adsorption properties for U(VI) were analysised by various characterization methods. The effect of time, initial pH, uranium concentration, temperature and ionic strength on Batch U(VI) adsorption were investigated from the aspects of adsorption kinetics, isotherms and thermodynamics. X-ray diffraction spectra (XRD), scanning electron microscopy - energy dispersive spectroscopy (SEM/EDS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectra (FTIR) were used to characterize and analyse the adsorption behavior and mechanisms.

Results

The results show that the equilibrium adsorption capacity of uranium is about 115.0 mg?g-1 when the initial uranium concentration is 50.00 mg?L-1 at pH 4.0 and 25 ℃. The U(VI) adsorption amount of nZVI@CA/ZIF-8 increases with the increase of initial pH, initial U(VI) concentration and temperature, and maintains good U(VI) adsorption performances even at high Na+ ionic concentration (0.5 mol·L-1). The equilibrium adsorption capacity of uranium is about (110.0±5.0) mg·L-1 when the initial uranium concentration is 50.00 mg·L-1 at pH 4.0 and 25 ℃. The adsorption is a spontaneous endothermic monolayer chemical process, which can be deduced by the pseudo-second-order kinetic and Freundlich models. Brunauer Emmett teller (BET) measurement suggests that nZVI@CA/ZIF-8 displays a porous structure and a large specific surface area (1 271 m2?g-1). Results of XRD and SEM-EDS demonstrate that the crystal structure and microscopic morphology of ZIF-8 and nZVI are present in the composite. Test results of XPS and FTIR verify that U(VI) can be reduced to U(IV) by nZVI particles exists the nZVI particles could reduce on the surface of composite in the form of UO2. Moreover, nZVI@CA/ZIF-8 can also adsorb U(VI) from the solution by forming Zn-O-U coordination bonds.

Conclusions

This study can provide technical and theoretical references for the synthesis of metal-organic framework composites and the study of its U(VI) removal from radioactive wastewater.

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NUCLEAR ELECTRONICS AND INSTRUMENTATION
Study on spectrum stabilization technique for a portable LaBr3(Ce) gamma spectrometer
Chen CHEN,Huan WU
Nuclear Techniques. 2021, 44 (4):  40401-040401.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040401
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Background

As one of the most important issues in the field of gamma spectrum analysis, the main function of spectrum stabilization is to suppress the "spectral line drift" caused by environmental changes. Portable LaBr3(Ce) gamma spectrometer is mainly used to analyze and process the gamma spectra of radionuclides and obtain qualitative and quantitative information about radionuclides. It often works in the field complex environment where the spectrum drift is inevitable, hence must have the function of spectrum stabilization.

Purpose

This study aims to improve the performance of spectrum stabilization technique for a portable LaBr3(Ce) gamma spectrometer.

Methods

The intrinsic characteristic peak of LaBr3(Ce) detector and the peak of 40K in the natural background were made of as the reference peaks. Then, the concept of "spectrum similarity" was defined to calculate the similarity between the measured spectrum and the standard background spectrum. Finally, a new spectrum stabilization method using standard reference peak and "spectrum similarity" was proposed to measure and correct the deviation. Experiments were carried out verify the performance of this new method.

Results

Experimental results show that the technology can effectively stabilize spectrum in the temperature range of -30 ℃ to 50 ℃ without calibration of the relationship curve between the reference peak and the temperature, and the peak drift of the reference peak is stable within ±1 channel even if the temperature changes more than 50 ℃?h-1.

Conclusions

This technology effectively improves the application range of portable LaBr3(Ce) spectrometers.

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Development of a super-high rang γ monitor for high temperature and pressure environment
Guangzhi SUN,Shunli QIU,Wei XIAO,Le ZENG,Haifeng LIU,Yu PEI,Mengtuan GE,Yulin ZHOU,Hui CHENG
Nuclear Techniques. 2021, 44 (4):  40402-040402.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040402
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Background

Under accident conditions of nuclear power plants, radiation measurement is needed in the high temperature, high humidity and high pressure environment in the containment vessel where the ordinary radiation monitor does not work normally.

Purpose

This study aims to design and implement a super-high range γ-dose monitor used in the high temperature and high pressure environment of nuclear power station containment vessel.

Methods

The overall design of the monitor, the structure design of the ionization chamber detector, the calculation of the compressive strength of the detector, and the design of a wide range weak current measurement circuit were carried out based on current-voltage-frequency conversion. The ionization chamber detector located in the containment vessel could bear with the lose of coolant accident (LOCA) environment with high temperature up to 200 ℃ and high pressure of 0.7 MPa. The monitor was calibrated by standard radioactive installation and mega radioactive device. Then the LOCA experiment vessel to was employed to test the high temperature and pressure endurance.

Results

Test resultresult shows that the monitor has good sensitivity linearity within the range of 1 mGy·h-1 to 50 000 Gy·h-1, and can provide stable signal under LOCA environment.

Conclusions

The device is suitable for γ radiation monitor under accident conditions.

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Ion pulse ionization chamber for online measurements of the radon activity concentration
Tianli QIU,Meng LI,Xianglun WEI,Herun YANG,Peng MA,Chengui LU,Limin DUAN,Rongjiang HU,Zhoubo HE,Juncheng LIANG,Ming ZHANG
Nuclear Techniques. 2021, 44 (4):  40403-040403.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040403
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Background

Radon and its daughters are seriously harmful to human respiratory organs.

Purpose

This study aims to accurately measure the concentration of radon in ambient air by ion pulse ionization chamber for online measurements.

Methods

Based on the principle that alpha rays emitted by radon and its daughters ionize air molecules, a detection system based on ion pulse ionization chamber was developed to record the information of single radioactive particles and accurately measure the concentration in the air. Double shielding structure to adopted to suppress the noise effectively for the detector, and ionized data was obtained by ion pulse collection and oscilloscope waveform sampling. The radon content in the air was measured in different locations, and the effective signals and counts were obtained.

Results & Conclusions

The measurement results show that the full width at half maximum (FWHM) of the 241Am alpha particle energy resolution is 17% under the detector's working voltage range of -400 to -1?200 V. The radon concentrations in the air measured at two campus sites in Lanzhou city are (22.05±0.86) Bq·m-3 and (20.31±0.84) Bq·m-3, respectively, that conform to the provisions of GB/T 50325?2020 on indoor radon concentration.

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Simulation study on time resolution optimization of silicon drift detector
Nian YU,Yupeng XU,Yanke CAI,Yuxuan ZHU,Xiaofan ZHAO,Can CHEN
Nuclear Techniques. 2021, 44 (4):  40404-040404.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040404
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Background

The silicon drift detector (SDD) has been widely used in space exploration in recent years. The SDD has outstanding energy resolution, but its time resolution is not very satisfactory. The charge packet generated by the interaction between the incident photon and the detector takes some time to drift to anode. The drift time depends on the distance between the interaction position and the anode, and usually can't be measured directly. Therefore, the uncertainty of drift time is the main factor that affects the time resolution of the SDD system.

Purpose

This study aims to propose a method called pulse amplitude ratio to measure the drift time so as to improve the time resolution of the SDD system.

Methods

The correspondence between the drift time and the rise time of the output signal of the charge sensitive amplifier (CSA) was made use of. The rise time was measured by the pulse amplitude ratio of triangular and trapezoidal shaping, hence the drift time was obtained by measuring the pulse amplitude ratio. Matlab/Simulink module and Xilinx module of system generator were used to build the system for simulation of the readout chain for pulse amplitude ratio measurement. The relationship between pulse amplitude ratio and CSA output signal, and the influence of SDD and CSA electronic noise on pulse amplitude ratio were investigated in details.

Results

Simulation results show that the pulse amplitude ratio of the shaping network only depends on the rise time, and the electronic noise of SDD and CSA can cause the measurement error.

Conclusions

The influence of electronic noise of SDD can be reduced by using optimized parameters of the shaping network, and the accuracy of the corrected arrival time can be improved by about one order of magnitude.

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NUCLEAR PHYSICS, INTERDISCIPLINARY RESEARCH
Numerical simulation of controllable source neutron porosity logging based on CLYC detector
Yue ZHOU,Huawei YU,Meng WANG,Benqiang DU,Zhijie LIU
Nuclear Techniques. 2021, 44 (4):  40501-040501.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040501
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Background

Using Cs2LiYCl6:Ce (CLYC) instead of 3He detector in neutron porosity logging has become a new idea for the development of logging tools.

Purpose

This study aims to investigate the feasibility of using a new CLYC crystal based detector in neutron porosity logging.

Methods

The Monte Carlo simulation method was employed to study the thermal neutron counting flux of 6Li CLYC detector with different purities and sizes. Thermal neutron counting of this new detector was compared with that of 3He detector under different pressures, the replacement of CLYC detector was verified according to the neutron porosity response of different detectors.

Results

The results show that the new CLYC detector has high thermal neutron counting efficiency when its purity of 6Li and size are large. Compared with 3He detector, the CLYC detector with low thermal neutron detection efficiency has a near/far detector ratio similar to that of 3He detector after optimizing the combination of source diatances which can be effectively applied to obtain formation porosity.

Conclusions

This study provides a theoretical basis for the detector selection and replacement of neutron porosity logging tools in the future.

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NUCLEAR ENERGY SCIENCE AND ENGINEERING
Simulation study on COPRA corium pool based on COMSOL
Guangyu ZHU,Jinkun MIN,Li ZHANG,Yidan YUAN
Nuclear Techniques. 2021, 44 (4):  40601-040601.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040601
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Background

COMSOL is considered to be an ideal approach to study the complicated physical processes in the corium pool because of its good simulation ability in multiphysics field.

Purpose

This study aims to build a computational model by COMSOL to explore the turbulent flow field and phase change in the corium pool.

Methods

Based on non-isothermal flow calculation module, the non-eutectic binary mixture of 20%NaNO3-80%KNO3 used in COrium Pool Research Apparatus (COPRA) experiment was simulated by using phase-change material model. The radiation heat transfer in the closed cavity at the top of corium pool was translated into the radiation heat transfer between the upper surface and the environment available as boundary condition in COMSOL.

Results

Simulation results show that in addition to the evident natural convection main flow, a mass of vortexes are existed in the corium pool, which lead to the thermal stratification of the corium pool in steady-state. Under the influence of natural convection main flow and gravity, the crust thickness along the cooling wall surface decreases with the vessel polar angle of corium pool increases.

Conclusions

The current computational model is helpful for severe accident mitigation system design.

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Study on the reinforcement process and performance of carbon fiber fabric for graphite control rod guide tube of molten salt reactor
Bo HUANG,Hong JIANG,Zhoutong HE,Fanggang LIU,Hui TANG,Xingtai ZHOU
Nuclear Techniques. 2021, 44 (4):  40602-040602.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040602
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Background

The control rod guide tube (CRGT) is needed to facilitate the movement of the control rod in the molten salt reactor (MSR). Graphite material is resistant to neutron radiation, high temperature and molten salt corrosion, and has small neutron absorption cross section, hence it is an ideal CRGT material except for the comparatively low strength and toughness. It is believed that reinforcing the graphite CRGT with carbon fiber fabric (CFF) is a promising way to promote its application in molten salt reactor.

Purpose

This study aims to optimize the preparation parameters of the CFF reinforcement for CRGT.

Methods

First of all, the CFF was pre-impregnated with precursor solution in a vacuum environment, and wound on the graphite tube with a certain tension. Secondly, samples with different densification cycles and winding layers were prepared through multiple pressure impregnation, curing and carbonization cycles of the Precursor-Infiltration-Pyrolysis (PIP) process. Then, the mechanical properties of carbon fiber cloth reinforced graphite tube samples and the reference samples were tested. Finally, the microstructure and failure mode of the damaged samples were analyzed for further optimizing the preparation process to improve the material performance.

Results & Conclusions

The results show that the CFF winding and PIP method enhances the strength and toughness of the graphite tube, and the preparation parameters have been optimized that make the reinforced graphite CRGT with carbon fiber fabric (CFF) possible to be applied to MSR.

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Development and verification of fuel management code for liquid-fueled molten salt reactor based on deterministic code system
Kaicheng YU,Maosong CHENG,Zhimin DAI
Nuclear Techniques. 2021, 44 (4):  40603-040603.  DOI: 10.11889/j.0253-3219.2021.hjs.44.040603
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Background

Molten salt reactor (MSR), a candidate of the Generation IV reactors, has the advantages of inherent safety and good neutron economy. The circulation flow of fuel, on-line refueling and reprocessing are the three features of liquid fuel in MSR. Due to the features of liquid fuel, the fuel management regulations for conventional reactors that use solid fuels are not applicable to liquid-fueled MSR.

Purpose

This study aims to develope a new fuel management code named ThorNEMFM to analyze liquid fuel management of MSR.

Methods

First of all, the self-developed deterministic code ThorCORE3D was coupled with the cross section processing module and a burnup calculation module. Then a fuel management analysis program ThorNEMFM was developed for liquid fuel molten salt reactor to realize on-line feeding and fission product processing. Finally, the ThorNEMFM was verified on molten salt reactor experiment (MSRE), molten salt breeder reactor (MSBR) and molten salt fast reactor (MSFR).

Results

The results of benchmarks for MSRE, MSBR and MSFR indicate that ThorNEMFM has a high accuracy with benchmarks in comparison with the reference.

Conclusions

ThorNEMFM is suitable for calculation and analysis of fuel management of MSR.

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Application of super-resolution optical microscopy in biology
MAO Xiuhai, DU Jiancong, HUANG Qing, FAN Chunhai, DENG Suhui
Nuclear Techniques    2013, 36 (6): 60502-060502.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.060502
Abstract453)      PDF(pc) (6093KB)(6420)       Save

Background: A noninvasive, real-time far-field optical microscopy is needed to study the dynamic function inside cells and proteins. However, the resolution limit of traditional optical microscope is about 200 nm due to the diffraction limit of light. So, it’s hard to directly observe the subcellular structures. Over the past several years of microscopy development, the diffraction limit of fluorescence microscopy has been overcome and its resolution limit is about tens of nanometers. Methods: To overcome the diffraction limit of light, many super-resolution fluoresce microcopies, including stimulated emission of depletion microscopy (STED), photoactivation localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM), have been developed. Conclusions: These methods have been applied in cell biology, microbiology and neurobiology, and the technology of super-resolution provides a new insight into the life science.

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Cited: Baidu(3)
Research status of energy dispersive X-ray fluorescence spectrometer
ZHAO Fengkui, WANG Aimin
Nuclear Techniques    2013, 36 (10): 100402-100402.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.100402
Abstract207)      PDF(pc) (1792KB)(5086)       Save

Background: Energy dispersive X-ray fluorescence spectrometer has been improved rapidly in these years. Purpose: Research status of energy dispersive X-ray fluorescence spectrometers is reviewed, covering the main components in the spectrometer and spectra processing algorithms. Methods: On the component aspect, the working principles and performances of high-voltage generator, X-ray excitation sources, especially X-ray tubes and detector are compared. On the spectra processing aspect, results of different algorithms in spectrum de-noising, background subtraction, decomposition of the peaks and calculating the intensity of the fluorescence are analyzed separately. Results: On the component aspect, the effects to sensitivity and resolution of the spectrometer being caused by the high-voltage of the voltage generator, intensity of X-ray and resolution of the detector are concluded. On the spectra processing aspect, feasibilities of various algorithms are suggested. The advantages of wavelet transform, artificial neural network and partial least-squares method are discussed. Conclusion: Present difficulties in further improving of the spectrometer performance are analyzed. The prospect and the necessity of further research of EDXRF have been suggested.

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Cited: Baidu(1)
Calibration method and experiment based on I/Q demodulation principle
ZHANG Zhigang, ZHAO Yubin, XU Kai, ZHENG Xiang, LI Zheng, ZHAO Shenjie, CHANG Qiang, HOU Hongtao, MA Zhenyu, LUO Chen, MAO Dongqing, SHI Jing, WANG Yan, LIU Jianfei
Nuclear Techniques    2015, 38 (3): 30102-030102.   DOI: 10.11889/j.0253-3219.2015.hjs.38.030102
Abstract459)      PDF(pc) (1625KB)(3770)       Save
Background: In-phase/Quadrature (I/Q) demodulation technology is widely used in radio frequency signal phase control system. As the intrinsic errors in hardware, such as the imbalances of gain and phase in 90° hybrid and 0° hybrid, direct current (DC) offsets and phase errors from length difference of circuits, the output signal is an ellipse and the output phase is nonlinear to the input radio frequency (RF) signal. The detection of phase precision is influenced. Purpose: This study aims to reduce the effects of errors existed in the I/Q demodulators. Methods: A calibration method for I/Q demodulation technique is proposed and applied to research and development of I/Q integrate circuits, which is based on the surface mounted devices (SMD) chip. Results: Experimental tests showed that the phase error was less than ±0.15°, the amplitude stability was less than ±1%, and the channel delay was less than 10 ns. Conclusion: This calibration method, together with the designed circuit board for the RF signal front end preprocessing can reduce the effects of intrinsic errors efficiently. It has been being used in upgrading of beam trip diagnostic system in the storage ring of Shanghai Synchrotron Radiation Facility (SSRF).
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Cited: Baidu(2)
Thermophysical properties of liquid lead-bismuth eutectic
SU Ziwei, ZHOU Tao, LIU Mengying, ZOU Wenzhong
Nuclear Techniques    2013, 36 (9): 90205-090205.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.090205
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Background: Liquid lead-bismuth eutectic (LBE) is important spallation target materials and candidate coolant materials in accelerator driven subcritical (ADS)system. Purpose: Its thermodynamic physical properties are keys to understand the basic problems in ADS R&D. Methods: By the calculation of scientific laws as well as fitting other scholars’ experimental results, we tried to obtain the above thermodynamics physical properties. Results: By the calculation, we got formula about characteristic temperatures, density, specific heat, viscosity and thermal conductivity of liquid lead-bismuth alloy. And by fitting other scholars’ experimental results, we got the fitting formula. Conclusions: Finally, by the contrast analysis, we found that the fitting formula and calculation formula agree well, and fitting formula more approaches the experimental value with a high accuracy whose differential deviation is not over 1%.

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Cited: Baidu(9)
Decay time characteristics of plastic scintillator
HUANG Zhanchang, YANG Jianlun
Nuclear Techniques    2015, 38 (6): 60203-060203.   DOI: 10.11889/j.0253-3219.2015.hjs.38.060203
Abstract529)      PDF(pc) (677KB)(3302)       Save
Background: The plastic scintillator is mostly used for the inertia confinement fusion determination systems. It is necessary to know the scintillator decay time. Purpose: The aim is to measure the decay time of the plastic scintillator and analyze the applicability of single photon method. Method: The plastic scintillator is excited by 137Cs, and the decay time of the plastic scintillator is measured by single photon method. The ST401 and EJ232 plastic scintillators are measured by this device. The theory of single photon method is analyzed via statistics and the measurement process is simulated by Monte Carlo method. Results: The results are 2.9 ns with 50 ns for ST401 and 1.6 ns with 30 ns for EJ232 via double exponential fitting. The device has a dynamic range of over 104 and an intrinsic time resolution under 0.8 ns. The experiment result agrees to the simulated one. Conclusion: The comparison between the experiment result and the simulation result indicates that with the mean counts of stop detector no more than 0.1, the result measured by single photon method can be approximated to the decay time of plastic scintillator.
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Synchrotron μ-XRF and XAFS in element distribution and speciation of air, soil and biological samples
YUAN Jing, LUO Liqiang
Nuclear Techniques    2014, 37 (08): 80101-080101.   DOI: 10.11889/j.0253-3219.2014.hjs.37.080101
Abstract385)      PDF(pc) (1225KB)(3023)       Save
Background: Synchrotron radiation micro probe analysis technique has been improved rapidly in recent years. Accurate qualitative or quantitative information on the interest element in environmental and biological samples such as atmospheric particles, soil, plant and earthworm plays a crucial role in the understanding of the effect of these elements in the samples. However, determination of these samples with complex matrices is a difficulty in multiple disciplines. With the rapid development of this area, the synchrotron-based techniques have been introduced to this area and have been widely used in analyzing various complex samples due to its superiority in fast and non-destructive determination. Purpose: In this review, the synchrotron source and its advantages in investigation on elemental analysis of the complex natural samples are introduced. Then, the applications of Synchrotron micro-X-ray fluorescence (μ-SXRF) and Synchrotron X-ray absorption fine spectroscopy (XAFS) in atmospheric particles, soil, plant and earthworm are reviewed, covering the distribution and the speciation of elements in these samples. Methods: μ-SXRF permits in situ mapping of biologically important elements of the sample even at sub-micrometer scale so that the spatially resolved element distribution maps can be obtained. XAFS allows determination of the speciation of high heterogeneity samples by providing the element oxidation state and local coordination environment. Results and Conclusion: μ-SXRF and XAFS have been widely used in element distribution and speciation of nature samples, especially for micro scale samples or micro area of samples such as atmospheric particles, soil, plant and earthworm. It is relevant to study thoroughly the presence, source, mobilization and fate of the elements using the information. Some challenges and future perspectives of the research and the tendency of development of synchrotron radiation technology have also been suggested.
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Cited: Baidu(1)
Pulse shape discrimination and energy calibration of EJ301 liquid scintillation detector
CHANG Le, LIU Yingdu, DU Long, WANG Yuting, CAO Xiguang, ZHANG Guoqiang, WANG Hongwei, MA Chunwang, ZHANG Song, ZHONG Chen, LI Chen
Nuclear Techniques    2015, 38 (2): 20501-020501.   DOI: 10.11889/j.0253-3219.2015.hjs.38.020501
Abstract1099)      PDF(pc) (1146KB)(2878)       Save
Background: EJ301 liquid scintillation detector has good time characteristics, pulse shape discrimination ability and the neutron detection efficiency. Purpose: This study aims to achieve the energy calibration, the pulse shape discrimination (PSD) ability etc. of EJ301 organic liquid scintillation detector. Methods: The waveform digital sampler DT5720 and digital pulse processing-pulse shape discrimination (DPP-PSD) control software were employed to simplify the data acquisition system. The pulse shape discrimination parameters such as the widths of long and short gates could be set up by software. The Compton peaks of 241Am (0.0595MeV), 137Cs-60Co (0.662 MeV, 1.171MeV, 0.662 MeV) and 40K (1.461 MeV) sources were used to obtain experimental data for pulse shape discrimination and the energy calibration of EJ301. Results: Experimental results show EJ301 detector has high efficiency, strong neutron/gamma-PSD ability. Conclusion: DT5720 and DPP-PSD control software have powerful function and are easy to use for both the PSD and energy calibration of EJ301. EJ301 organic liquid scintillation detector can be used for neutron measurement, and is suitable for measuring fast neutron energy spectrum and time of flight.
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Cited: Baidu(9)
Design of high voltage power supply of miniature X-ray tube based on resonant Royer
LIU Xiyao, ZENG Guoqiang, TAN Chengjun, LUO Qun, GONG Chunhui, HUANG Rui
Nuclear Techniques    2013, 36 (8): 80403-080403.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.080403
Abstract506)      PDF(pc) (1714KB)(2827)       Save

Background: In recent years, X rays are widely used in various fields. With the rapid development of national economy, the demand of high quality, high reliability, and high stability miniature X-ray tube has grown rapidly. As an important core component of miniature X-ray tube, high voltage power supply has attracted wide attention. Purpose: To match miniature, the high voltage power supply should be small, lightweight, good quality, etc. Based on the basic performance requirements of existing micro-X-ray tube high voltage power supply, this paper designs an output from 0 to ?30 kV adjustable miniature X-ray tube voltage DC power supply. Compared to half-bridge and full-bridge switching-mode power supply, its driving circuit is simple. With working on the linear condition, it has no switching noise. Methods: The main circuit makes use of DC power supply to provide the energy. The resonant Royer circuit supplies sine wave which drives to the high frequency transformer’s primary winding with resultant sine-like high voltage appearing across the secondary winding. Then, the voltage doubling rectifying circuit would achieve further boost. In the regulator circuit, a feedback control resonant transistor base current is adopted. In order to insulate air, a silicone rubber is used for high pressure part packaging, and the output voltage is measured by the dividing voltage below ?5 kV. Results: The stability of circuit is better than 0.2%/6 h and the percent of the output ripple voltage is less than 0.3%. Keeping the output voltage constant, the output current can reach 57 ?A by changing the size of load resistor. This high voltage power supply based on resonant Royer can meet the requirement of miniature X-ray tube. Conclusions: The circuit can satisfy low noise, low ripple, low power and high voltage regulator power supply design. However, its efficiency is not high enough because of the linear condition. In the next design, to further reduce power consumption, we could improve the efficiency by controlling the current of resonant circuit.

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Cited: Baidu(3)
A method of communication between EPICS IOC and EtherCAT devices
HE Yongcheng, WANG Chunhong, WU Xuan
Nuclear Techniques    2014, 37 (11): 110102-110102.   DOI: 10.11889/j.0253-3219.2014.hjs.37.110102
Abstract691)      PDF(pc) (913KB)(2751)       Save
Background: EtherCAT (Ethernet Control Automation Technology) is a kind of real-time Ethernet fieldbus protocol for industrial automation. The control system of many large-scale scientific facilities such as Beijing electron-positron collider (BEPCII), Chinese spallation neutron source (CSNS) was designed based on EPICS (Experimental Physics and Industrial Control System). Purpose: The aim is to implement EtherCAT as a real-time high speed control system solution for the EPICS based control system. Methods: The communication between EPICS IOC (Input/Output Controller) and EtherCAT devices was realized by using the OPC (Object Linking and Embedding for Process Control) Gateway driver. A real-time temperature monitoring appliance was taken as testing example. Results: The test results show that the communication between EPICS IOC and EtherCAT devices using the OPC Gateway driver is efficiently implemented. Conclusion: EtherCAT devices can be applied to communicate with the EPICS IOC to achieve real-time high-speed control by using the OPC Gateway driver.
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Cited: Baidu(2)
Physics design of a compact medical cyclotron
HE Xiaozhong, YANG Guojun, LONG Jidong, PANG Jian, ZHANG Kaizhi, SHI Jinshui
Nuclear Techniques    2014, 37 (01): 10201-010201.   DOI: 10.11889/j.0253-3219.2014.hjs.37.010201
Abstract489)      PDF(pc) (1105KB)(2724)       Save

Background: A compact cyclotron with energy of 11 MeV and current of 50 ?A is under construction in Institute of Fluid Physics of China Academy of Engineering Physics. The compact cyclotron is developed for medical isotope production. Purpose: To minimize the cost and to shorten the time of the development of the compact cyclotron, a lot of efforts were dedicated to the physics design of the compact cyclotron. Methods: Physics design of the main magnet was performed using TOSCA software, and start-to-end beam dynamics design was performed using home-made software CYCDYN. Results: Physics design of the compact cyclotron was given in details. Design methods and results of the main subsystems (including ion source, radial sector focusing magnet, RF cavity, central region and extraction system) were also given in this paper. Conclusion: Now commissioning of this cyclotron has been finished, and the goal for extracting proton beams of 11 MeV and 50 uA on average has been achieved. Physics design of the cyclotron has been validated by the commissioning results.

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Cited: Baidu(3)
Research on 1.6-GeV proton translation process using Geant4
YAO Zhiming, SONG Guzhou, HEI Dongwei, MA Jiming, ZHOU Ming, DUAN Baojun, SONG Yan, HAN Changcai
Nuclear Techniques    2014, 37 (03): 30205-030205.   DOI: 10.11889/j.0253-3219.2014.hjs.37.030205
Abstract491)      PDF(pc) (732KB)(2696)       Save

Backgroud: Chinese Spallation Neutron Source under construction consists of a proton accelerator which can speed up protons to 1.6 GeV. High-energy proton beams are used for radiography due to their high penetrability. Purpose: In order to understand how protons interact with materials when transmitting an object, the transport process of 1.6-GeV protons in different materials is simulated by Geant4. Methods: Energy loss, multiple coulomb scattering, inelastic and elastic collisions with nucleus are simulated independently by setting the physics process in Geant4. Beryllium, copper and tungsten are chosen as low-Z, middle-Z and high-Z material respectively. With respect to the effect of thickness, Tungsten of 5 g?cm?2, 10 g?cm?2 and 15 g?cm?2 is chosen as the material. Results: Number, energy and direction of motion are changed after protons penetrate an object. Changes are related to the composition and thickness of materials. Conclusion: The simulation results imply that transmission, energy-loss and distribution of scattering angle can reflect the thickness (in g?cm?2) and material composition of an object.

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Application progress of solid 29Si, 27Al NMR in the research of cement-based materials
FENG Chunhua, WANG Xijian, LI Dongxu
Nuclear Techniques    2014, 37 (01): 10502-010502.   DOI: 10.11889/j.0253-3219.2014.hjs.37.010502
Abstract329)      PDF(pc) (273KB)(2644)       Save

Background: The solid-state Nuclear Magnetic Resonance (NMR) is an effective method for the research of cement-based materials. Now it focuses on using solid 29Si and 27Al NMR to research the hydration structure of the cement-based materials in cement chemistry. Purpose: A theoretical guidance is proposed for solid 29Si and 27Al NMR technology used in cement chemistry research. Methods: We reviewed the application of solid 29Si and 27Al NMR in the cement-based materials and analyzed the problem among the researches. Results: This paper introduced an fundamental, relevant-conditions and basic parameters of NMR, and studied the technical parameters of solid 29Si and 27Al NMR together with the relationship among the hydration structure of cement-based material. Moreover, this paper reviewed the related domestic and overseas achievements in the research of hydration structure of the cement-based materials using solid 29Si and 27Al NMR. Conclusion: There were some problems in the research on cement-based materials by technology of solid 29Si and 27Al NMR. NMR will promote the Hydration theory of cement-based material greatly.

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Cited: Baidu(2)
Measurement and study of the photocathode quantum efficiency of photoelectric conversion device
XIA Jingkai, QIAN Sen, WANG Wenwen, NING Zhe, CHENG Yaping, WANG Yifang, JIANG Xiaoshan, WANG Zheng, LI Xiaonan, QI Ming, HENG Yuekun, LIU Shulin
Nuclear Techniques    2014, 37 (09): 90401-090401.   DOI: 10.11889/j.0253-3219.2014.hjs.37.090401
Abstract580)      PDF(pc) (784KB)(2584)       Save
Background: Photoelectric devices such as photomultiplier tubes (PMTs), photo diodes (PDs) and solar cells are widely used in many applications, so reliable evaluation on the performances of such devices is quite necessary, especially for the accurate measurements and calibrations on the photocathode quantum efficiency (QE). Purpose: We aim to build up a cathode performance evaluation system and study the properties of different types of cathodes. Methods: Two different methods named as the relative measurement and the direct measurements were employed to measure the QE values of cathodes. In addition, a 2D platform was built to achieve convenient and accurate processes for the plane type photocathode position uniformity test. Results: With the evaluation system, the cathode properties of dozens of photoelectric devices were tested. The measured QE results, either from the relative or the direct measurement, are consistent with the data provided by the manufacturers or a third party. Conclusion: Our cathode evaluation system is reliable and could be used to study the detailed photocathode properties such as QE, spectral response and position uniformity.
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Cited: Baidu(1)
Monte Carlo calculation of dose point kernel and absorbed dose distribution for electrons and photons
CHEN Shaowen, HUANG Long, WU Muying, TANG Qiang, LIU Xiaowei, ZHANG Chunxiang
Nuclear Techniques    2013, 36 (7): 70205-070205.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.070205
Abstract425)      PDF(pc) (1953KB)(2567)       Save

Background: The dose point kernel and the absorbed fraction are essential in the absorbed dose calculation for radionuclide therapy. Purpose: To calculate the scaled dose point kernels for 1MeV monoenergetic electrons and 32P, 90Y , 131I radionuclides, the absorbed fractions for 0.2 MeV and 4 MeV monoenergetic electrons and 32P, 90Y radionuclides which uniformly distributed in water spheres of various mass ranging from 10?2 to 103 g, and the radial distributions of absorbed dose rates for 32P, 131I, 90Y nuclides and 15 keV, 30 keV, 100 keV photons which uniformly distributed in a water (tumor) spherical shell (0.22?r?0.66cm) with an activity of 1MBq/cm3. Methods: EGSnrc Monte Carlo programs were used for simulation. Results: The calculation results were compared with those of other works. Conclusions: The results could give some help to absorbed dose calculations for radionuclide therapy.

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Cited: Baidu(1)
GEANT4 simulation and imaging reconstruction by backprojection algorithm for Compton camera
DING Changji, MAO Benjiang, YUAN Yonggang, JIANG Zhigang, YANG Chaowen
Nuclear Techniques    2015, 38 (11): 110402-110402.   DOI: 10.11889/j.0253-3219.2015.hjs.38.110402
Abstract938)      PDF(pc) (2109KB)(2535)       Save
Background: Due to its imaging principle advantages and the development of detectors, nuclear electronics, Compton camera has once again put forward. Purpose: This study aims to build a Compton camera via Monte Carlo simulation and test its backprojection algorithm. Methods: By using Monte Carlo simulation software GEANT4, a Compton camera with stripes structure is designed and data for reconstruction image of source is read out. Backprojection imaging reconstruction algorithm is studied for getting the reconstruction of source. Results: Using backprojection algorithm and simulated Compton camera, when the distance between source and the scattering detector is 40 mm, the spatial resolution is FWHM=8.0 mm, angular resolution is 3° and γ photon imaging efficiency is 0.38%, which are better than most of the pinhole and coded aperture γ camera imaging. Conclusion: Because of the existence of large amount of data, Compton camera needs long calculation time for measuring data. The next step is improving simulated Compton camera to study its performance parameters, while the maximum likelihood algorithm could improve the spatial resolution of Compton camera.
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Cited: Baidu(1)
Design of nuclear imaging system based on MURA coded aperture collimator
CHEN Lihong, LI Yongping, ZHAO Cuilan, YUAN Chao
Nuclear Techniques    2013, 36 (8): 80402-080402.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.080402
Abstract470)      PDF(pc) (1691KB)(2513)       Save

Background: Location nuclear imaging systems have been used in many fields, such as astronomical observation, radioactive source monitoring, nuclear development, biomedicine, etc. Purpose: It puts forward much higher requirements of monitoring and control of safety of nuclear facilities and radioactive sources. In this paper, a new portable nuclear imaging system is designed, which can be used in far field imaging. Methods: It uses high resolution detector which consists of LaBr3 crystal and H8500 position sensitive photomultiplier to meet the design requirements of high resolution. In order to acquire the higher radiation collection efficiency, we choose modified uniformly redundant arrays (MURA) as system collimator. It uses the maximum likelihood-expectation maximization (MLEM) algorithms in reconstruction procedure. Results: The test results show that the imaging system can image the far field radioactive source clearly. The field-of-view of our system can achieve the design goal: ±10°?±20°, and its resolution can be variable among 0.923°?2.038°. Conclusions: It can meet the design requirements of resolution and FOV very well. This radiation imaging system can achieve miniaturization and portability radiation imaging robot which is suited for the long-range control.

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Cited: Baidu(2)
P3HT/PCBM polymer thin films studied by synchrotron-based grazing incidence X-ray diffraction
YANG Yingguo, ZHENGGUAN Haojie, JI Gengwu, FENG Shanglei, LI Xiaolong, GAO Xingyu
Nuclear Techniques    2014, 37 (02): 20101-020101.   DOI: 10.11889/j.0253-3219.2014.hjs.37.020101
Abstract565)      PDF(pc) (1612KB)(2489)       Save

Background: The microstructures of P3HT (poly(3-hexyl-thiophene)) in P3HT/PCBM ([6,6]-phenyl C61-butyric acid methyl ester) thin films play a key role in governing the performance of organic solar cells (OSCs) based on these films. Purpose: We aim to study the self-organization of P3HT in the P3HT/PCBM thin films annealed at different temperatures. Methods: Using different incidence angles, information about the microstructures of P3HT at different depths in these films was obtained by synchrotron based grazing incidence X-ray diffraction (GIXRD). Results: It is shown that the crystalline structure of P3HT has been substantially improved by thermal annealing. One dimensional GIXRD clearly indicates that P3HT edge-on structures in the inner layers have been improved with their number increased in comparison with those at the surface and the interface layers. In addition, thermal annealing also helps the formation of P3HT face-on structures in the films, as evidenced by 2 dimensional GIXRD. Conclusion: The improved structures in these films lead to more charge transport channels formed to improve the carrier mobility, which in turn helps the improvement of OSCs. Thus, the present GIXRD results will improve the understanding of annealing effects at different depths of the P3HT/PCBM thin films for enhanced OSCs devices.

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Preparation of FLiNaK molten salt
ZONG Guoqiang, CHEN Bo, ZHANG Long, SUN Jiahong, DONG Qun’an, CHEN Wei, XIAO Jichang
Nuclear Techniques    2014, 37 (05): 50604-050604.   DOI: 10.11889/j.0253-3219.2014.hjs.37.050604
Abstract824)      PDF(pc) (716KB)(2474)       Save

Background: Possessing a series of advantages, such as low neutron absorption cross section, much lower vapor pressure and good heat transfer performance fluoride molten salts are widely used in the high-temperature hydrogen, solar storage, nuclear fuel and other energy fields. Among them, ternary mixture of LiF-NaF-KF (FLiNaK) is one of the most common candidate molten salt systems. Purpose: We aim to examine the effect of temperature, time, crucible material and fluoride reagents on the quality of the molten salt, and preliminarily master key process parameters for preparation of FLiNaK molten salt. Methods: The formation of FLiNaK molten salt was studied by a vacuum melting platform. The optional preparation conditions were obtained through the screening of melting temperature, timing, crucible material and fluorination reagent. Results: In the presence of NH4HF2, the oxygen content in FLiNaK salt could be controlled below 2×10?4. Metal ion impurities in molten salt, according to the general requirements of the quality standard for molten salt reactor, of which Be, Cu, Fe, Zr and Cd contents are less than 5×10?6. And impurities of sulfate and phosphate anions are less than 1×10?4 and 3×10?5, respectively. Conclusion: Using the present preparation method, the corrosion of furnace was greatly reduced. It was an efficient, low-cost, and safe process for the preparation of FLiNaK molten salt.

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Cited: Baidu(9)
Calculation and analysis of radioactive source term in PWR assemblies
CHEN Haiying, QIAO Yahua, WANG Shaowei, CHEN Yan, LAN Bing, ZHANG Chunming
Nuclear Techniques    2014, 37 (04): 40601-040601.   DOI: 10.11889/j.0253-3219.2014.hjs.37.040601
Abstract517)      PDF(pc) (473KB)(2453)       Save

Background: When fission occurs in fuel of reactor core, it produces a large amount of radioactive materials, which may cause harm to the environment and human health. Purpose: The radioactive materials in fuel could provide input data for shielding design of reactor coolant radioactive source term, analysis of accident source term and radioactive consequence assessment. Methods: The calculation of radioactive source in fuel was studied for pressurized water reactor, the calculation methods and models were established using ORIGEN-S, and the difference of nuclides radioactivity under different burnup was also studied. The effect of different versions of ENDF/B cross-section database on the calculation results was analyzed, so as to provide a basis for the calculation of radioactive source in fuel. Results: The results showed that the method established by ORIGEN-ARP was more suitable for calculating radioactive source term in fuel assemblies and the different versions of ENDF/B database had a great impact on radioactivity calculation. Conclusion: Based on the ENDF/B-VII database, using ORIGEN-ARP to calculate radioactive source term in fuel assemblies could not only improve efficiency, but also improve the calculation accuracy.

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Cited: Baidu(1)
Real-time signal transmission performance tests with optical fiber based on Aurora protocol
LU Ruiqi, ZENG Jianping, ZHAO Yubin, REN Hailong
Nuclear Techniques    2015, 38 (3): 30404-030404.   DOI: 10.11889/j.0253-3219.2015.hjs.38.030404
Abstract481)      PDF(pc) (569KB)(2447)       Save
Background: General Purpose Powder Diffractometer (GPPD) is one of Chinese Spallation Neutron Source (CSNS) diffractometers, which adopts Symptom Scale of Neurotransmitter Deficiency (SSND) detecting the position and the flight time of neutron when it hits, and the electronics system processes the detected neutron information. The shooting time T0, as a time reference point of the electronics system, is a real time signal. Traditional cable transmission meets the real-time signal transmission requirements, however, laying work will be rather complex and bring great difficulties to project since numerous of cable was needed. Purpose: The electronics control circuits is needed to transfer the received signal T0 to the lower electronics in real time with low propagation delay and low jitter via optical fiber, and the the propagation delay is less than 1 μs which including the 15-m optical fiber delay, the jitter is less than 0.1 μs. Methods: This paper describes a transferring scheme based on Spartan6 XC6SLX75T FPGA using Aurora protocol via optical fiber. The testing program is based on ISE Design Suite14.4 FPGA development platform, adopting high-precision oscilloscopes to the measure and calculate the transmission delay and jitter of different rise time signal T0 repeatly. Results: Repeated measurements show that the maximum propagation delay is less than 600ns and that the maximum jitter is less than 4 ns, in addition, the stability of jitter stability is good, and it meets the system requirements. Conclusion: It is feasible to use Aurora protocol via optical fiber to transfer real-time signal T0. Signal rise time has a certain influence on the delay and jitter, longer signal rise time corresponds longer delay and greater the jitter, so to shorten rise time of signal can reduce the transmission delay and jitter.
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Detection efficiency simulation and measurement of 6LiI/natLiI scintillation detector
DU Long, CHANG Le, WANG Yuting, ZHANG Song, CAO Xiguang, WANG Hongwei, ZHANG Guoqiang, ZHONG Chen, LI Chen
Nuclear Techniques    2014, 37 (04): 40201-040201.   DOI: 10.11889/j.0253-3219.2014.hjs.37.040201
Abstract496)      PDF(pc) (658KB)(2403)       Save

Background: Being of very high detection efficiency and small size, Lithium iodide (LiI) scintillator detector is used extensively in neutron measurement and environmental monitoring. Purpose: Using thermal reactor, neutron detectors will be tested and calibrated. And a new neutron detector device will be designed and studied. Methods: The relationship between the size and detection efficiency of the thermal neutron detector 6LiI/natLiI was studied using Monte Carlo code GEANT4 and MCNP5 package, and the thermal neutron efficiency of detector was calibrated by reactor neutrons. Results: The theoretical simulation shows that the thermal neutron detection efficiency of detector of 10-mm thickness is relatively high, the enriched 6LiI is up to 98% and the nature natLiI 65%. The thermal neutron efficiency of detector is calibrated by reactor thermal neutrons. Considering the neutron scattering by the lead brick, high density polythene and environment neutron contribution, the detection efficiency of 6LiI detector is about 90% and natLiI detector 70%. Conclusion: The detector efficiency can reach the efficiency value of theoretical calculations.

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Cited: Baidu(9)
MCNP coupled with post-processing software application development
HE Zehong, YE Minyou, WANG Zhongwei, MAO Shifeng, XU Kun
Nuclear Techniques    2015, 38 (6): 60601-060601.   DOI: 10.11889/j.0253-3219.2015.hjs.38.060601
Abstract789)      PDF(pc) (911KB)(2391)       Save
Background: Neutron flux and thermal distributed computing are vital parts of the process of nuclear fusion reactor design, its representative calculation software MCNP is based on the Monte Carlo method. However, the output of MCNP is a text file, thus the results are not conveniently and visually represented by manual analysis, and cannot be directly imported into post-processing software such as Ensight, Paraview and ANSYS for processing. Purpose: In order to enhance the efficiency of data analysis of MCNP output, a coupling program between the MCNP and post-processing software is proposed and implemented in this paper. Methods: The Microsoft Visual Studio 2010 (VS2010) is taken as a development platform, the coupling program is developed using C/C++ programming language to perform numerical/logic operations and various kinds of data format conversion required by post-processing software such as Ensight, Paraview and ANSYS, etc. Results: The coupling program was tested via “while-box” method, logical operations of MCNP calculation results, and data format conversion of MCNP data file processed by this program are satisfied for the requirement of the post-processing software for visual analysis. Conclusion: It provides effective support tools that bridge the connection between MCNP and the post-processing software for practical engineering design.
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Research of accelerator-based neutron source for boron neutron capture therapy
LI Changkai, MA Yingjie, TANG Xiaobin, XIE Qin, GENG Changran, CHEN Da
Nuclear Techniques    2013, 36 (9): 90203-090203.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.090203
Abstract458)      PDF(pc) (2256KB)(2335)       Save

Background: 7Li(p,n) reaction of high neutron yield and low threshold energy has become one of the most important neutron generating reactions for Accelerator-based Boron Neutron Capture Therapy(BNCT). Purpose: Focuses on neutron yield and spectrum characteristics of this kind of neutron generating reaction which serves as an accelerator-based neutron source and moderates the high energy neutron beams to meet BNCT requirements. Methods: The yield and energy spectrum of neutrons generated by accelerator-based 7Li(p,n) reaction with incident proton energy from 1.9 MeV to 3.0 MeV are researched using the Monte Carlo code-MCNPX2.5.0. And the energy and angular distribution of differential neutron yield by 2.5-MeV incident proton are also given in this part. In the following part, the character of epithermal neutron beam generated by 2.5-MeV incident protons is moderated by a new-designed moderator. Results: Energy spectra of neutrons generated by accelerator-based 7Li(p,n) reaction with incident proton energy from 1.9 MeV to 3.0 MeV are got through the simulation and calculation. The best moderator thickness is got through comparison. Conclusions: Neutron beam produced by accelerator-based 7Li(p,n) reaction, with the bombarding beam of 10 mA and the energy of 2.5 MeV, can meet the requirement of BNCT well after being moderated.

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Software management in EPICS environment
LEI Lei, HAN Lifeng, XU Haixia, LI Yongping
Nuclear Techniques    2015, 38 (6): 60501-060501.   DOI: 10.11889/j.0253-3219.2015.hjs.38.060501
Abstract494)      PDF(pc) (579KB)(2319)       Save
Background: Compared with commercial SCADA (Supervisory Control and Data Acquisition) software, EPICS (Experimental Physics and Industrial Control System) control system has no uniform way for software management at present. Developers in different projects deploy and invoke EPICS software modules in different ways. However, it is particularly important to manage the software modules scientifically and normatively for projects like thermonuclear fusion reactor, proton therapy and Thorium Molten Salt Reactor (TMSR), which helps to improve the reliability, maintainability and usability of system. Purpose: We aim to deploy EPICS software modules automatically and call them normatively. Methods: We implement the directory management using Linux Filesystem Hierarchy Standard (FHS), deploy software modules with Red Hat Package Manager (RPM) and shell scripts and manage all software modules with Linux service. Results: The scheme runs very well and reduces manual operation greatly. Conclusion: The results indicate that this scheme can address some issues in the usage of EPICS, which may help to build a unified, fully automated software platform for TMSR I&C system.
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CFD simulation analysis and validation for CPR1000 pressurized water reactor
ZHANG Mingqian, RAN Xiaobing, LIU Yanwu, YU Xiaolei, ZHU Mingli
Nuclear Techniques    2013, 36 (10): 100601-100601.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.100601
Abstract245)      PDF(pc) (5349KB)(2300)       Save

Background: With the rapid growth in the non-nuclear area for industrial use of Computational fluid dynamics (CFD) which has been accompanied by dramatically enhanced computing power, the application of CFD methods to problems relating to Nuclear Reactor Safety (NRS) is rapidly accelerating. Existing research data have shown that CFD methods could predict accurately the pressure field and the flow repartition in reactor lower plenum. But simulations for the full domain of the reactor have not been reported so far. Purpose: The aim is to determine the capabilities of the codes to model accurately the physical phenomena which occur in the full reactor vessel. Methods: The flow field of the CPR1000 reactor which is associated with a typical pressurized water reactor (PWR) is simulated by using ANSYS CFX. The pressure loss in reactor pressure vessel, the hydraulic loads of guide tubes and support columns, and the bypass flow of head dome were obtained by calculations for the full domain of the reactor. The results were validated by comparing with the determined reference value of the operating nuclear plant (LingAo nuclear plant), and the transient simulation was conducted in order to better understand the flow in reactor pressure vessel. Results: It was shown that the predicted pressure loss with CFD code was slightly different with the determined value (10% relative deviation for the total pressure loss), the hydraulic loads were less than the determined value with maximum relative deviation 50%, and bypass flow of head dome was approximately the same with determined value. Conclusion: This analysis practice predicts accurately the physical phenomena which occur in the full reactor vessel, and can be taken as a guidance for the nuclear plant design development and improve our understanding of reactor flow phenomena.

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Cited: Baidu(1)
Research on the key technology of high-power solid-state pulse modulator
LI Feng, CHEN Zhihao, WU Yonghua
Nuclear Techniques    2013, 36 (7): 70104-070104.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.070104
Abstract458)      PDF(pc) (1674KB)(2278)       Save

Background: For construction of free-electron laser (FEL) apparatus, we designed a high-power solid-state modulator system based on the module of insulated gate bipolar transistor (IGBT) switch. Purpose: To meet the higher performance requirements of linear accelerator microwave power source for the FEL. Methods: The module circuit of the high-power modulator is introduced, as well as the critical auxiliary circuit including protection circuit of IGBT, damping circuit, demagnetization circuit and compensating circuits. Results: The whole modulator system is simulated by using software and the module differences that may occurred. The modulator with inductive adder topology can generate a 130 kV, 100A and 13MW pulse power. Conclusions: The results show that the inductive adder pulse modulator technology is feasible.

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A numerical method for extracting dual-energy value of X-ray transmission image based on MCNP
XIANG An, CHEN Ruitao
Nuclear Techniques    2014, 37 (07): 70203-070203.   DOI: 10.11889/j.0253-3219.2014.hjs.37.070203
Abstract328)      PDF(pc) (1384KB)(2257)       Save
Background: Traditional dual-energy X-ray inspection technology serves to classify different materials based on the proper value related with effective atomic number. Purpose: This paper aims to solve the problem of the relevance between the proper value and material’s thickness (thickness effect), which reduces the reliability of dual-energy inspection technology. Methods: A numerical method which combines Simpson formula and sequential quadratic programming (SQP) method is proposed to eliminate the thickness effect of dual-energy values. The process of X-ray inspection is simulated by Monte Carlo method based on MCNP. Probability-classification method is used to evaluate the effectiveness of diminishing error probability of material-classification, and classification boundaries of different materials. A practical X-ray inspection machine is used to verify this method. Results: The experimental results indicate that not only the thickness effect is diminished obviously by this method, but also the classification boundaries are effectively achieved. Conclusion: The dual-energy value of X-ray transmission image can be extracted by our proposed method with effectiveness and practical applicability.
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Measurement of γ absorption dose rate through measuring the full energy peak of γ spectrum
HE Jun, YANG Chaowen
Nuclear Techniques    2014, 37 (07): 70403-070403.   DOI: 10.11889/j.0253-3219.2014.hjs.37.070403
Abstract574)      PDF(pc) (704KB)(2238)       Save
Background: At present most radiation dose meters have the serious problem of energy response, and they just use the count rate plus relative correction method to measure the dose rate. This method has large error, and cannot distinguish the type of radionuclide, also cannot obtain the contribution of each radionuclide to the dose rate. Purpose: The research of new method is to measure the dose rate and improve the accuracy of measurement. Methods: The method of γ dose rate measurement through measuring full energy peak of γ spectrum was put forward, the angular response function of parallel γ ray injected into detector was defined. The average angular response over full space in the energy range from 0.02 MeV to 3 MeV was calculated by Monte Carlo simulation for ?50mm×50mm NaI(Tl) detector. Measurement tests have been done using standard radioactive sources of 137Cs, 60Co, 152Eu, 133Ba and in reference radioactive field of 137Cs, 60Co, 226Ra, 241Am in a national lab. Results: The test errors are smaller than 2% compared with the theoretical value for standard sources, and smaller than 3% compared with the value of PTW 10 L spherical chamber for reference radiation field. Conclusion: The results show that the method is suitable for the dose rate measurement for a wide range of energy without experimental calibration, can calculate the dose rate of different energy ray, and at the same time identify the radioactive nuclides in the radiation source.
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Cited: Baidu(1)
Optimizing design for the maze exit of a 10-MeV electron irradiation accelerator
DUAN Zongjin, CHEN Yukai, REN Guangyi, HE Lijuan, LI Yuxiong, CHEN Zhi
Nuclear Techniques    2013, 36 (11): 110203-110203.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.110203
Abstract261)      PDF(pc) (3938KB)(2232)       Save

Background: Irradiation accelerator is being used more and more widely, but the optimizing of radiation shielding is always a problem to be solved. Purpose: To make the dose rates of the maze exit lower and the cost to achieve it less, it is of great significance to design a shielding which is cheap and effective. Methods: The radiation dose rates at different maze exits of a 10-MeV industrial electron linear accelerator were compared by formula and Monte Carlo (Fluka) method. A real-time measurement system composed of Mini Digital Data Logging (Mini-DDL) and Gamma detectors was also used. Results: With one corner added to the exit, another scattering would be generated. The dose rate of exit before changing was 3?4?Gy?h?1 while it was 200nGy?h?1 after that. Conclusion: The radiation dose rate at the exit will be reduced by one order of magnitude because of another scattering generated by the added turn to the maze exit. All of these do not increase any additional cost and conform to the ALARA (as low as reasonably achievable) principle. It provides a good reference for the future design of shielding for industrial electron linear accelerator.

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Cited: Baidu(4)
High temperature gas-cooled pebble bed reactor steady state thermal-hydraulics analyses based on CFD method
SONG Shixiong, WEI Quan, CAI Xiangzhou, GUO Wei
Nuclear Techniques    2013, 36 (12): 120601-120601.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.120601
Abstract626)      PDF(pc) (4976KB)(2148)       Save

Background: Based on general purpose CFD code Fluent, the PBMR-400 full load nominal condition thermal-hydraulics performance was studied by applying local thermal non-equilibrium porous media model. Purpose: In thermal hydraulics study of the gas cooled pebble bed reactor, the core of the reactor can be treated as macroscopic porous media with strong inner heat source, and the original Fluent code can not handle it properly. Methods: By introducing a UDS in the calculation domain of the reactor core and subjoining a new resistance term, we develop a non-equilibrium porous media model which can give an accurate description of the core of the pebble bed. The mesh of CFD code is finer than that of the traditional pebble bed reactor thermal hydraulics analysis code such as THERMIX and TINTE, thus more information about coolant velocity fields, temperature field and solid phase temperature field can be acquired. Results: The nominal condition calculation results of the CFD code are compared to those of the well-established thermal-hydraulic code THERMIX and TINTE, and show a good consistency. Conclusion: The extended local thermal non-equilibrium model can be used to analyse thermal-hydraulics of high temperature pebble bed type reactor.

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Cited: Baidu(1)
Method of digital Dither adding for digital multi-channel pulse amplitude analyzer
CHEN Xiaomeng, ZHANG Yuzhong, AI Xianyun, LIANG Weiping, XIAO Wuyun
Nuclear Techniques    2015, 38 (5): 50401-050401.   DOI: 10.11889/j.0253-3219.2015.hjs.38.050401
Abstract450)      PDF(pc) (2008KB)(2148)       Save
Background: The key technology of digital multi-channel pulse amplitude analyzer (DMCA) has been surmounted in China, however, with the increasing of the translation gain increases of DMCA, one of the difficulties is how to make the nonlinear performance index of the system reach the standard. Technology of Dither has been used to realize “Bit Gain” in overseas research while it is still a deficiency in DMCA study in China. Purpose: This study aims to study the application of Dither technology in DMCA and discuss relevant digital Dither technology for DMCA. Method: Based on DMCA architecture characteristics, Dither signal is produced and removed in field programmable gate array (FPGA) by linear feedback shift register (LFSR), and is added to DMCA by the circuit of base line. Energy resolution and differential nonlinearity (DNL) of DMCA system has been measured to study the effect of Dither on DMCA. The mechanism of how the Dither affects DMCA has been analyzed. Results: Experimental tests showed that DNL of DMCA is improved by adding Dither while keep the same the energy resolution, verifying the applicability of this method. Conclusion: The technology method of digital Dither adding for DMCA is of practical significance to the further research to improve the precision of DMCA.
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Cited: Baidu(9)
Micro SR-XRF analysis on underglaze copper red porcelain of Ming dynasty
GUAN Li, ZHU Jian, FAN Changsheng, YANG Yimin, CHEN Dongliang, XU Wei, ZHANG Jing, WANG Lihua
Nuclear Techniques    2013, 36 (7): 70103-070103.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.070103
Abstract341)      PDF(pc) (1341KB)(2146)       Save

Background: The firing techniques of producing underglaze copper red porcelain emerged in the Yuan dynasty and reached its maturity during the Ming and Qing Dynasties in Jingdezhen city. The technique of producing underglaze red porcelain was sensitive to the firing temperature and atmosphere, so it was very hard to produce and also difficult to display red color under the surface successfully. Purpose & Methods: The micro SR-XRF technique was employed to analysis a piece of sherd of underglaze copper red porcelain of early Ming dynasty. The Chemical compositions of glaze and color areas were presented, and the elemental contents in different color areas were obtained by using line-scanning techniques. Results: Some elements such as As and Pb were contained in raw materials, and the content of Cu had obviously increased with the color changing from gray to red. The results indicated that the nature mineral possibly used as the pigment for underglazed copper red porcelain coloration, and the color appearance also depends on the amount of copper in the pigments contained. Conclusions: This paper presents the advantage of the synchrotron radiation XRF technology and contributes to the science evidences for the Chinese ancient porcelain handcraft research.

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Turbulent heat transfer of liquid metal inside the sub-channels of reactor core
GE Zhihao, PENG Yongsheng, LYU Yijun, DENG Weiping, ZHAO Pinghui
Nuclear Techniques    2015, 38 (9): 90603-090603.   DOI: 10.11889/j.0253-3219.2015.hjs.38.090603
Abstract478)      PDF(pc) (1254KB)(2141)       Save
Background: Liquid metal has been proposed as the coolant of the fourth generation nuclear reactor and the accelerator driven sub-critical system. Due to its low molecular Prandtl number (Pr), liquid metal differs from other coolants like water or gas in heat transfer. Purpose: This study aims to investigate the character of heat transfer of liquid metal inside the reactor core. Methods: Speziale-Sarkar-Gatski (SSG) Reynolds stress model was applied to the Computational Fluid Dynamics (CFD) prediction of liquid metal flow and heat transfer inside the sub-channels of the reactor core. Effect of different dimensionless parameters, e.g. Reynolds number (Re), Pr, Grashof number (Gr) and pitch-to-diameter ratio (P/D) on the turbulent heat transfer calculated results was investigated. Results: The dimensionless convective heat transfer coefficient (Nu), predicted by the CFD method, agrees well with the experimental data and the empirical relations. Conclusion: Based on the analysis of various dimensionless parameters, it is found that the heat exchange performs better in triangular fuel assembly sub-channels than that in square sub-channels, under the same condition of P/D and Re. The inhomogeneous circumferential distributions of temperature and heat transfer can be effectively improved by increasing Re and P/D or choosing coolants with large Pr. When Re is larger than 10000, the buoyancy effect on liquid metal heat transfer could be ignored.
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PWR core transient temperature numerical simulation based on porous media model
CHEN Sen, LIU Yu, TIAN Maolin, TIAN Wenxi, QIU Suizheng, SU Guanghui
Nuclear Techniques    2015, 38 (9): 90601-090601.   DOI: 10.11889/j.0253-3219.2015.hjs.38.090601
Abstract388)      PDF(pc) (1552KB)(2135)       Save

Background: The coolant flow and heat transfer in the reactor are significant to the safety of pressure water reactor (PWR). Purpose: This study aims to obtain the coolant flow and heat transfer characteristics in the reactor core. Methods: The complete model of pressure vessel is built by Pro/E, and the thermal hydraulic characteristics of the core are simulated with commercial software CFX by using the porous medium model in the core. Results: The simulation results show that the application of porous media model can display the core coolant temperature distribution effectively and correctly, and the asymmetric operation conditions can cause asymmetric on reactor core. The transient accident calculation results show that the highest temperature of the coolant appears in the upper of the core. Conclusion: The porous media model can be used in the reactor core and it has a certain reference value for the thermal-hydraulic safety of pressurized water reactor.

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Comparative analysis and measurement of focus spot for X-ray source
SUN Chaoming, TANG Guangping, LI Qiang, WANG Zengyong
Nuclear Techniques    2015, 38 (11): 110202-110202.   DOI: 10.11889/j.0253-3219.2015.hjs.38.110202
Abstract492)      PDF(pc) (5036KB)(2121)       Save
Background: Image quality in radiographic testing is often conditioned by the size and distribution of X-ray source. However, determination of focal spot is not performed effectively in practice, thus it is difficult to accurately control the image quality in the testing. Purpose: This study aims to obtain a quick and efficient test method to evaluate the focal spot for X-ray source. Methods: Test tools such as pinhole plate, star test pattern and duplex wire image quality indicator (IQI) were used to measure the focal spot of a portable X-ray source separately. Several measurements were carried out and compared in details. Results: Results of star test pattern and duplex wire IQI were coincident, but different from the results of pinhole imaging method obviously. Conclusion: Nominal focal spot size of an X-ray source may be considerably different from that in practice use, so it is necessary to timely evaluate characteristics of the focal spot. The duplex wire IQI can usually replace star test pattern to measure un-sharpness in radiographic testing images and to evaluate focal spot size.
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Three-dimensional visualization of fibrochondrocytes in rabbit patella-patellar tendon junction using synchrotron radiation-based X-ray phase contrast tomography
CHEN Huabin, HU Jianzhong, ZHOU Jingyong, ZHENG Cheng, WANG Zhanwen, CHEN Can, CAO Yong, YIN Xianzhen, LYU Hongbin
Nuclear Techniques    2015, 38 (11): 110101-110101.   DOI: 10.11889/j.0253-3219.2015.hjs.38.110101
Abstract351)      PDF(pc) (3229KB)(2108)       Save

Background: Synchrotron radiation-based X-ray phase-contrast computed tomography (SR-XPCT) is an advanced tool for nondestructive analysis of three dimensional inner microstructure of samples, and plays an important part in the researches such as spinal cord microvasculature and lung bronchium. Purpose: This study was to investigate the three-dimensional morphology of fibrochondrocytes in rabbit patella-patellar tendon junction (PPTJ) using SR-XPCT, and develop an advanced imaging method. Methods: Three PPTJs were harvested from healthy mature female New Zealand rabbits. The specimens were scanned by SR-XPCT at BL13W1 of Shanghai Synchrotron Radiation Facility (SSRF) in China. The tomographic image was captured by Charge Coupled Device (CCD) detector with a 0.65-μm resolution. The three-dimensional visualization images of PPTJ were reconstructed by VG Studio Max. After that, the specimens were embedded by paraffin for Safranin O/Fast-green staining. Results: High-resolution three-dimensional visualization images of PPTJ and the parameters of the chondrocytes in fibrocartilage zone were successfully obtained via the SR-XPCT. With spherical and ellipsoidal morphologic features and its configuration characteristics in three dimension, the fibrochondrocytes revealed by SR-XPCT were consistent with the results of traditional histological staining. The parameters of chondrocytes showed that the mean diameter of chondrocyte was (10.139±1.265) μm, the mean volume was (291.187±87.283) μm3 and 75.4% of the chondrocytes’ volume ranged from 200 μm3 to 400 μm3, the mean sphericity degree was 0.711±0.079, and 84.9% of chondrocytes’ sphericity degree ranged from 0.605 to 0.805. Conclusion: The three-dimensional microstructure of the PPTJ was intuitively, accurately and undistortedly realized by the SR-XPCT, which may act as a novel instrument to access the three-dimensional microstructure changes during the PPTJ healing process.

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Influencing factors of dose equivalence for X and γ rays with different energy based on Monte Carlo
GUO Huiping, LYU Wenhui, LYU Ning, WEI Zhihao
Nuclear Techniques    2014, 37 (01): 10203-010203.   DOI: 10.11889/j.0253-3219.2014.hjs.37.010203
Abstract317)      PDF(pc) (1144KB)(2076)       Save

Background: The accuracy of dosimeter measurement of X and γ rays needs to be resolved. Purpose: The aim is to study the correction term of the equivalent process of low-energy X-ray and the natural radioactive source. Methods: Instead of the standard sources, X-ray machine was adopted on the dose instrument calibration. The influence factors of the equivalence between low-energy X-ray and high-energy X or γ rays were simulated using Monte Carlo (MCNP) software. Results: The influences of distance, space scattering, response of detector on dose equivalence were obtained. The simulation results were also analyzed. Conclusion: The method can be used in dose equivalent correction for low-energy X-ray, high-energy X or γ rays, which is significant for the widespread use of X rays.

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Radio-synthesis and application research advance of amino acid molecular tracers labeling with 18F and 11C for tumor PET imaging
HE Shanzhen, WANG Shuxia, WANG Peng, LI Shilei, TANG Ganghua
Nuclear Techniques    2014, 37 (08): 80302-080302.   DOI: 10.11889/j.0253-3219.2014.hjs.37.080302
Abstract361)      PDF(pc) (905KB)(2049)       Save
Background: Positron emission tomography (PET) is in rapidly developing as a powerful imaging technique for diagnosis, efficacy evaluation and prognosis of tumor. In contrast to 18F-FDG, the amino acid tracers were helpful additional tools for differentiating tumor tissue and inflammation, edematous, necrotic and fibrotic tissue because of their low uptake in those tissues, so that amino acid tracers appear to be more specific than the widely used 18F-FDG. As a result, a number of attempts have been undertaken for radio-synthesis of amino acid with short half-life nuclide 18F and 11C. Purpose: The aim is to review and discuss the present knowledge on synthesis methods and preliminary clinic application of labeling amino acid. Methods: The advances on the synthesis methods and preliminary clinic application of labeling amino acid in recent years were introduced and discussed. Results: In recent years, many new 18F or 11C-labeled amino acids have been developed and their preliminary clinic applications were studied. Conclusion: The review provides an overview of this class of radiolabeled amino acids and highlights the current synthesis status and the key preliminary clinic applications.
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Impact of dust storm on chemical species of S, Cl and Ca in Shanghai atmosphere particles
LONG Shilei, LIU Ke, ZENG Jianrong, CAO Lingling, BAO Liangman, LIN Jun, LI Yan, MA Chenyan
Nuclear Techniques    2013, 36 (10): 100101-100101.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.100101
Abstract225)      PDF(pc) (2372KB)(2045)       Save

Background: Dust storm originated from the northwest region of China brought dust particles for Shanghai every spring, which resulted in serious particulate pollution. However, the studies of the impact of dust storm on the Shanghai atmospheric aerosols were limited to the concentrations of ions and elements. It is considered that the chemical species of atmospheric aerosols were much more necessary for the evaluation of the impact of dust storm on the particulate pollution in Shanghai. Purpose: Based on the elements concentration variations, backward trajectories of air masses and chlorine, calcium, sulfur species in aerosols during the dust event, the impact of dust storm on the chemical species of aerosols in Shanghai was studied. Methods: Elements concentrations of the samples were analyzed by X-ray fluorescence (XRF) based on synchrotron radiation. To identify the potential importance of different source regions on aerosol composition during dust events, the air mass trajectories were calculated by using the model HYSPLIT version 4 developed by NOAA/ARL. Chemical species of S, Cl, Ca were analyzed by synchrotron radiation X-ray absorption near edge structure (XANES). Sulfur K-edge XANES is capable of distinguishing various sulfate species in a non-destructive way and we used linear combination fitting procedure to quantify the concentrations of sulfate species in PM. Results: Elements concentration variations during the dust storm period showed that crust elements (Si, Al, Ca, K, Mg, Fe, Ti) in particles increased substantially during dust storm. However, pollution elements (S, Zn, Pb, Cu, V, Cr, As) from local region decreased by the clean effect of dust storm. Combined XANES of S, Cl, Ca in particulate samples with backward trajectories, the possible sources and reasons of their chemical species were studied. During dust storm, sulfur mainly existed as CaSO4?2H2O, Cl existed as organic chloride and Cl?, Ca existed as CaCO3. In the samples of other days, sulfur was mainly existed as (NH4)2SO4, Cl existed as organic chloride and Ca existed as Gypsum. The source of Cl? was sea salts which brought by dust storm along the way. Gypsum (CaSO4?2H2O) was formed in the reactions of CaCO3 and SO42? during the transportation. Conclusion: It is shown that synchrotron radiation XANES is a powerful tool to identify chlorine, calcium and especially sulfur species in aerosol samples. Dust storm not only transported amount of crust particles but also brought particles along the way to atmosphere environment in Shanghai. During the transportation, dust particles could chemically react with the pollution particles of the local region.

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Synthesis of Dumbbell-like Au nanostructure and its light-absorbance study  
SHEN Jianlei, XU Yan, LI Kun, SONG Shiping, FAN Chunhai
Nuclear Techniques    2013, 36 (6): 60501-060501.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.060501
Abstract254)      PDF(pc) (9293KB)(2034)       Save

Background: By changing the size or the morphology of Au nanostructures, they can absorb different wavelength light due to the localized surface plasmon resonance (LSPR). Because Au nanorods show good ability to transform light into heat (photothermal effect), they have been wildly used to deliver the drugs and release them controllably. However, when applying such nanostructures for in vivo treatments, Au nanorods must have long aspect ratio which often make it hard to prepare heterogeneous nanostructures. Purpose: A new method to synthesize Au nanostructures with uniform size and to achieve long wavelength light absorbance is needed. This work attempts to synthesize such Au nanostructures by using bio-nano techniques. Methods: New nanostructures are prepared by growing Au nanoparticles on the surface of Au nanorods modified with DNA molecules. Results: Dumbbell-like Au nanostructures were prepared firstly. Its maximum absorbance locates at near ultraviolet region, which means that it can be used as a potential tool for the deep-skin photothermal treatment. Moreover, other two kinds of nanostructures, i.e. Au nanorods with Au splinter at two ends and sea urchin-like nanostructures, are also studied. Conclusions: We successfully fabricated novel Au nanostructures which can be used for drug delivery, surface-enhanced Raman spectroscopy and catalysis.

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A survey of heatpipe space nuclear reactor power supply
Ao WANG, Fengyang SHEN, Gu HU, Jian AN Weijian GUO
Nuclear Techniques    2020, 43 (6): 60002-060002.   DOI: 10.11889/j.0253-3219.2020.hjs.43.060002
Abstract492)   HTML16)    PDF(pc) (790KB)(616)       Save
Background

With the in-depth exploration of space, the power supply requirements for energy supply are gradually increasing. Space nuclear reactor power supply stands out in the deep space exploration mission due to its advantages of passivity, long life and high reliability, hence heat pipe nuclear reactor has become the focus of research in the field of space nuclear reactor.

Purpose

This study aims to evaluate the progress and technology of heat pipe space nuclear reactor used as power supply.

Method

First of all, the conceptual design of heatpipe reactor in the early stage and its application in Kilopower was summarized. Then the details of heatpipe power system (HPS), the heatpipe-operated mars exploration reactor (HOMER), safe affordable fission engine (SAFE) and Kilopower were investigated with emphasis on the structure design, fuel selection, heatpipe arrangement and power design of each reactor.

Results

This survey provides ideas and references for future research and design of heatpipe space nuclear reactor power system.

Conclusions

The design of heatpipe reactor is highly flexible and innovative. The use of different alkali metal heat pipes and thermoelectric conversion methods has a direct impact on the system power and the quality of the entire system. The combination of heat pipe and various thermoelectric conversion methods can be attempted.

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Preliminary design of modularized lead cooled small reactor
Huiwen XIAO, Xiang LI, Guoming LIU, Youqi ZHENG
Nuclear Techniques    2020, 43 (8): 80001-080001.   DOI: 10.11889/j.0253-3219.2020.hjs.43.080001
Abstract210)   HTML6)    PDF(pc) (2356KB)(72)       Save
Background

As the coolant of the reactor, lead and lead-based alloy has excellent thermal properties. Developing lead cooled reactor attracts has been practicing with major investment in many countries, such as European union countries, Russia, Korea, Japan, China and so on.

Purpose

This study aims at the preliminary design of modularized lead cooled small reactor.

Methods

First of all, the neutron transport, depletion, reaction coefficient and kinetic parameters were calculated by using SARAX, a fast reactor neutronics calculation software developed by Xi’an Jiaotong University. High enrichment fuel was adopt for compact light-weight, and two different enrichment fuel was chosen to flat the power distribution. Two group control rods and one group of emergency shutdown rods were placed in the core to satisfy the requirement of reactivity and emergency shutdown. The B4C with good absorbing capacity in fast and thermal energy region was used as the neutron absorb material of control rods while tungsten with high density and excellent neutron absorb capacity was mixed with B4C as the neutron absorber material of the emergency shutdown rods. Then neutronics parameters of reactor core were calculated from the beginning of full power operation to the whole life cycle.

Results

The calculation results show that the 6EFPY life length of this design is achieved, mass of actinide elements decreases and mass of 239Pu was increases apparently. Important reactivity feedback coefficients, such as coolant density coefficient, coolant void value and expansion coefficient are negative, and the value of control rods and safety rods are enough to shutdown reactor in the whole life cycle. Highest clad temperature and fuel center temperature, line power density are within allowed limits.

Conclusions

The main neutronics parameters in the whole life cycle of this preliminary design meet the safety requirements.

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Intelligent commissioning system based on EPICS and differential evolution algorithm for synchrotron radiation beamline
Yingzhi SHI, Mei GAO, Wenhong JIA, Guangzhi YIN, Xingyu GAO, Yonghua DU, Lifang ZHENG
Nuclear Techniques    2020, 43 (5): 50101-050101.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050101
Abstract200)   HTML11)    PDF(pc) (1311KB)(215)       Save
Background

In synchrotron radiation facilities, it is important to keep beamlines operating in optimal conditions. The debugging process is normally very time consuming due to the irregular light source beam point, and it is not easy to get global optimum.

Purpose

This study aims to develop an intelligent debugging system based on Experimental Physics and Industrial Control System (EPICS) and differential evolution algorithm for synchrotron radiation beamline commissioning.

Methods

First of all, based on the differential evolution algorithm, intelligent optimization model of beamline was established. Then the automatic optimization of beam adjusting process was implemented by using LabVIEW program and communication with the EPICS-based control system was achieved by CaLab interface module. Functions of the user interface, motion control, algorithm implementation and evolution processing were integrated in the LabVIEW program. Finally, this intelligent commissioning system was tested at the X-ray diffractive (XRD) beamline of SSRF (Shanghai Synchrotron Radiation Facility) for optimization of the beam flux at sample position by adjusting the beamline optical components.

Results & Conclusions

Online tests results show that this intelligent commissioning system converges to the optimal solution quickly, and the convergence time is about 30 min, more than one order of magnitude higher than manual optimization efficiency.

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Conceptual design of Mars molten salt reactor
Shihe YU, Qiang SUN, Heng ZHAO, Rui YAN, Yang ZOU, Bing LAN
Nuclear Techniques    2020, 43 (5): 50603-050603.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050603
Abstract192)   HTML9)    PDF(pc) (689KB)(183)       Save
Background

Mars exploration has recently become a mainstream trend in space research. The establishment of a Mars base is an inevitable choice for human to study and develop Mars. Compared with the solar energy storage system, the nuclear reactor as a Mars base energy system has significant advantages in terms of system mass, operational flexibility, and environmental robustness.

Purpose

This study aims to propose core design scheme of Mars molten salt reactor (M2SR-1) and calculation model in aspects of reactor physics, critical safety and thermal.

Methods

The Monte Carlo N Particle Transport Code (MCNP) and Oak Ridge Isotope Generation and Depletion Code (ORIGEN) were employed to establish core physical calculation model. Calculation and analysis were performed in aspects of physical, safety, thermal and so on.

Results

Computational results reveal that the scheme of M2SR-1 meets the requirement of 8-year-life under full power operation. Under different hypothesis falling environments, the effective multiplication factor of nuclear reactor is less than 0.98, satisfying the criticality safety requirements.

Conclusion

This study provides basic theoretical reference for the design of planet surface molten salt reactor.

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Design and verification of small intelligent programmable SiPM power supply
Huiliang HOU, Yuefeng HUANG, Maosong CHENG, Zhimin DAI
Nuclear Techniques    2020, 43 (6): 60402-060402.   DOI: 10.11889/j.0253-3219.2020.hjs.43.060402
Abstract161)   HTML7)    PDF(pc) (2678KB)(76)       Save
Background

As a new solid-state photosensor, silicon photomultiplier (SiPM) has high gain (106), low power consumption (supply current is several μA), small size (several square milimeters), low operating voltage (less than 100 V) and other advantages. Compared with traditional photomultiplier tube, SiPM does not affected by magnetic fields. However, there is a disadvantage that the gain of SiPM is greatly affected by temperature, the gain will decrease by about 5×105 for every 10 °C rise in temperature, which will have a greater impact on energy spectrum measurement and radiation imaging applications.

Purpose

This study aims to design and develop a small programmable SiPM power supply for temperature independent gain.

Methods

First of all, a high-voltage power supply module was designed for SiPM, making use of the gain regulation by voltage. Temperature sensor, DC-DC power chip, etc., were integrated into an ARM-based micro control unit (MCU) module for automatic SiPM power supply. Then the effect of voltage compensation to gain in the temperature range of 5 ℃ to 40 ℃ was verified by using digital multi-channel analyzer with comparison of the channels of full energy peak on the energy spectrum of 241Am source.

Results

The channel of full energy peak which indicates the gain of the SiPM is stable by using the voltage compensation (gain drift correction), and the maximum drift of the SiPM gain from 5 ℃ to 40 ℃ decreases from 87.3% before compensation to 2.76%.

Conclusions

Gain drift correction achieved by a small intelligent programmable SiPM power supply broadens the scope of SiPM application.

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Review of nuclear technology in the application of COVID-19 epidemic prevention and control
Zhe WANG, Fanyu LIN, Xian SUN, Gaoyang YE, Yuexiang LU
Nuclear Techniques    2020, 43 (12): 120001-120001.   DOI: 10.11889/j.0253-3219.2020.hjs.43.120001
Abstract151)   HTML13)    PDF(pc) (1884KB)(118)       Save

In the early stage of the outbreak of COVD-19 in Wuhan city at the end of 2019, the demand for medical protective equipment increased rapidly. Many problems emerged, such as poor quality and short supply of protective masks, shortage of medical supplies caused by long sterilization cycles, difficult treatment of the medical waste and wastewater of which might cause the secondary infection. Herein, three specific applications of nuclear technology were summarized to fight against the COVID-19. The first one is the nuclear pore membrane (NPM) produced by nuclear technology. It can be used to fabricate face masks with high filtration efficiency and good reusability after simple processing. Hence the problems of poor reusability and poor filtration effects of common disposable masks can be solved by using NPM technology. The second application is the radiation sterilization technology in the process of producing medical supplies such as masks and protective clothing. The long cycle of common sterilization technology makes the demand exceed supply whereas the radiation sterilization technology can greatly shorten the production cycle and increase output, which could alleviate the shortage of medical supplies in anti-epidemic process. The third application is the use of γ-ray, X-ray or high-energy electron to sterilize medical wastewater and garbage, among which massive of surviving coronavirus are still infectious. It can treat large-volume of wastewater rapidly with a broad vision of application. Due to these unique advantages, nuclear technology has been playing an important role in this epidemic prevention and control, it possesses broader development prospects in the future.

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FPGA remote firmware update method based on SiTCP communication protocol with rollback function
Zhang CHEN, Zheng WANG, Jun HU
Nuclear Techniques    2020, 43 (11): 110401-110401.   DOI: 10.11889/j.0253-3219.2020.hjs.43.110401
Abstract147)   HTML33)    PDF(pc) (796KB)(84)       Save
Background

Field programmable gate array (FPGA) is widely used in many places, including readout system of large-scale high-energy physics experiments. This kind of experiments usually has large electronic systems with thousands of channels implemented together with FPGAs. Furthermore, these detectors and electronics are often located in special environments such as radiation field, under water or underground, hence the traditional single FPGA update method with joint test action group (JTAG) cable becomes unsuitable or inapplicable.

Purpose

This study aims to realize FPGA remote firmware update without additional Ethernet chips or network protocol, and ensure the security mechanism of the process and multi-FPGA updating extendibility in the future.

Methods

A new approach using silicon transmission control protocol (SiTCP) technique was proposed. The update firmware in the UDP packages was sent under the SiTCP protocol by MATLAB in host computer to FPGA, and the process of Flash memory programming to update firmware was dominated by FPGA, placing the role of PHY and MAC chips. The secure rollback function was implemented in the modified structure of FPGA firmware with separate update data area and original data area.

Results

UDP broadcasting has the ability to multi-FPGA updating, remote firmware update is achieved and tested the secure rollback mechanism well.

Conclusions

This method is suitable for remote operation with advantages such as no need for additional Ethernet chips, built-in safety function to fall back to a known situation, and extendibility of multi-FPGA updating.

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Design of novel lead-free flexible composites for radiation protection and simulation of protective effect
Siqi YAN, Peng CHENG, Guangyi YU, Hanzhou LIU, Churan FEI, Xiaoping OUYANG
Nuclear Techniques    2020, 43 (5): 50201-050201.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050201
Abstract146)   HTML5)    PDF(pc) (783KB)(84)       Save
Background

The number of radioactive practitioners has increased rapidly due to the wide application of X-ray, resulting in widespread attention to radiation protection. Lead is commonly used as a shielding material, but is extremely toxic and harmful to human health. The lead-based protective clothing on the market is too heavy and uncomfortable to wear.

Purpose

This study aims to design flexible composites of lead-free for shielding X-ray of different energy ranges and evaluating its shielding effect.

Methods

The X-ray mass attenuation coefficients of high atomic number materials were calculated according to National Institute of Standards and Technology (NIST) method. Hence, the ideal functional fillers were selected as shielding materials instead of lead. The MCNP5 code was employed to evaluate protective performance of lead-free flexible composites consisting of various doped metal elements with high atomic number.

Results

Simulation results show that Bi doping is an ideal substitute for Pb doping, and Bi2O3 can be used as the first-rate functional filler in lead-free flexible composites. Shielding performance of the composite doped with Bi2O3 and Gd2O3 is obviously improved during the energy of 54~66 keV whilst the composites doped with Bi2O3 and W functional fillers achieve the best X-ray attenuation at around 70 keV of X-ray.

Conclusions

A variety of bismuth-based flexible composites have been designed to replace lead-based materials. Bi2O3 is the optimal filling material for X-ray scattering energy less than 54 keV, incorporation of two functional materials, Bi2O3 and Gd2O3, can effectively improve the absorption effect of the composites for X-ray scattering energy in range of 54~66 keV. In the energy range of 66~100 keV, incorporation of two functional materials, Bi2O3 and W, is the optimal filling method whilst it is best to fill Bi2O3 alone to shield X-ray scattering energy greater than 100 keV.

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Detector design and performance test for coded camera of large area and high sensitivity
Yan LI, Qiang WANG, Xianchao HUANG, Lei SHUAI, Daquan CAO, Yiwen ZHANG, Yao YANG, Xuanhou HU, Xiuzuo LIANG, Jun WU, Guoqiang ZENG, Zhiming ZHANG
Nuclear Techniques    2020, 43 (5): 50402-050402.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050402
Abstract138)   HTML14)    PDF(pc) (1410KB)(86)       Save
Background

The traditional gamma camera cannot locate the contaminated area of nuclear accident, and cannot obtain the information of the contaminated area and degree in real time.

Purpose

This study aims to develop a coded aperture gamma camera detector system with large area and high sensitivity.

Methods

A detector module of large area CsI (Tl) crystal array coupled with photomultiplier tube array was proposed. It consisted of 121 CsI (Tl) crystals at the size of 15 mm×15 mm×15 mm, and 2×2 array composed of 4 detector modules was taken as γ camera detector. Multi-channel readout electronics composed of amplification, filter shaping and single-to-differential conversion circuit was independently designed for readout processing of detector signals. Finally, the performance of this detector system was evaluated by experimental tests.

Results

The results indicate that the detector module can achieve the position resolution, and its average energy resolution is 9.4% under the excitation of 662 keV γ-ray.

Conclusions

The detector system can satisfied the design requirements of coded aperture γ camera of high sensitivity in terms of position resolution, energy resolution, uniformity of peak position and detection efficiency.

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A comparative study of PET-MRI brain quantitative accuracy: the effect of MRI based segmentation and PET based segmentation on SUVR calculation
Zaisheng LI, Shuangshuang SONG, Tianyi ZENG, Jie LU, Lingzhi HU, Qun CHEN
Nuclear Techniques    2020, 43 (5): 50301-050301.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050301
Abstract131)   HTML2)    PDF(pc) (1529KB)(164)       Save
Background

In clinical application and scientific research of positron emission tomography (PET), the standard uptake value (SUV) is commonly used for disease assessment. In order to reduce the deviations of SUV among clinical PET images, standard uptake value ratio (SUVR) based on a specific reference region is substituted for SUV. Accurate SUVR is hardly achieved directly from PET images due to the difficulty of accurately segmenting reference regions from PET images with low resolution and high noise. The integrated positron emission tomography-magnetic resonance imaging (PET-MRI) can simultaneously acquire MRI images and PET images, hence the combination of MRI image and PET image is expected to improve the accuracy of SUVR.

Purpose

This paper study aims to investigate the effect of MRI segmentation and PET segmentation on SURV calculation to improve the PET-MRI brain quantitative accuracy.

Methods

First of all, integrated PET-MRI was used to acquire MRI and PET images of 12-age-controlled healthy volunteers simultaneously. Then the MRI images and PET images were segmented into reference regions by the atlas-based method. Based on reference regions derived from MRI and PET respectively, the SUVRs of left / right cerebrum, cerebral cortex, cerebral white matter, frontal lobe, parietal lobe, temporal lobe and occipital lobe were calculated. For each group of SUVRs, the coefficient of variation (CV) of SUVRs was calculated to measure consistency level. Finally, quantitative analysis was performed to evaluate which segmentation method offered better SUVR consistency among volunteers.

Results

CV of SUVRs based on cerebellar gray matter from MRI images and PET images were 0.020/0.021, 0.023/0.026, 0.031/0.028, 0.028/0.031, 0.033/0.036, 0.022/0.024, 0.044/0.045 and 0.052/0.055, 0.054/0.055, 0.058/0.063, 0.053/0.058, 0.063/0.065, 0.048/0.050, 0.059/0.065 respectively. When the cerebellum was chosen as reference region, MRI results and PET results were 0.017/0.019, 0.021/0.025, 0.029/0.025, 0.026/0.030, 0.032/0.036, 0.020/0.022, 0.044/0.045 and 0.046/0.050,0.049/0.051, 0.052/0.057, 0.048/0.054, 0.059/0.061, 0.044/0.045, 0.056/0.062 respectively.

Conclusions

Compared with SUVRs based on reference region segmented from PET images, SUVRs based on reference region segmented from MRI images have better consistency with smaller coefficient of variation.

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Evaluation of super homogenization method for pin-by-pin core calculation
Bin ZHANG, Yunzhao LI, Hongchun WU
Nuclear Techniques    2020, 43 (6): 60001-060001.   DOI: 10.11889/j.0253-3219.2020.hjs.43.060001
Abstract131)   HTML7)    PDF(pc) (1169KB)(47)       Save
Background

The new generation of pin-by-pin calculation method has gradually become the state-of-the-art approaches along with the improvement of computer technology and the development of core design.The difference between the pin-by-pin calculation and the traditional two-step scheme leads to the homogenization technique difficult to implement.

Purpose

This study aims to evaluate super homogenization techniques for pin-by-pin core calculationwith emphasis on equivalent homogenization constants.

Methods

Super homogenization method was used as one of the main homogenization techniques of pin-by-pin calculation. For fuel assembly, the traditional super homogenization method was employed to generate the group constants. For reflector assembly with neutron leakage, the super homogenization method related to space leakage was applied to the generation of equivalent homogenization constant including super homogenization factor.

Results

Based on the three-dimensional C5G7 benchmark, the application performance of the super homogenization method in pin-by-pin calculation is evaluated. The eigen-value relative error of pin-by-pin calculation is -0.001 6, assembly-power and pin-power relative errors are less than 5.5%.

Conclusions

Numerical results showed that the pin-by-pin calculations have the higher accuracy than the assembly-homogenized results.

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3D imaging of rat brain neural network using synchrotron radiation
Shuntong KANG, Tong WU, Zhuohui CHEN, Mengqi ZHANG
Nuclear Techniques    2020, 43 (7): 70101-070101.   DOI: 10.11889/j.0253-3219.2020.hjs.43.070101
Abstract126)   HTML11)    PDF(pc) (1359KB)(101)       Save
Background

Synchrotron radiation technology has a wide application prospect. X-ray absorption contrast imaging can not only obtain the three-dimensional (3D) morphological structure of neurons, but also improve the effective spatial resolution of detection, which meets the requirements of micro-neural network imaging research. It is feasible and effective to construct high-resolution 3D visualization network of brain neural network when combined with Golgi-Cox staining.

Purpose

This study aims to explore the application of synchrotron radiation absorption contrast imaging technology in the observation of 3D imaging of Golgi-Cox-stained mouse brain micro-neural network.

Methods

Twelve normal C57 mice were randomly divided into two groups, A and B, and perfused with brain tissue. Group A was treated without staining. The brains of group B were stained with Golgi-Cox and dehydrated in gradient ethanol. Specimens were scanned for absorption contrast imaging at X-ray imaging and biomedical application beam line station (BL13W1) in Shanghai Synchrotron Radiation Facility (SSRF), and data processing was performed by using software such as Amira.

Results

The imaging results show that both the cerebellar neural network structure and single neuron morphology in mouse are accurately presented. X-ray absorption contrast imaging technology, as an advanced three-dimensional rendering method of microscopic neural network, provides a new three-dimensional visualization method for morphological research of mouse brain neurons.

Conclusions

Synchrotron radiation can achieve high-precision 3D neuroimaging, which overcomes the disadvantages of traditional staining 2D histology, such as the damage of sections to specimens. This method combined with Golgi-Cox staining, can be used for the construction of regional neural networks and non-destructive research on the integrity of the brain.

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PreSAXS1.0, a program package for small-angle scattering of X-ray data pre-analysis
Xiaoyun LI, Xiuhong LI
Nuclear Techniques    2020, 43 (9): 90101-090101.   DOI: 10.11889/j.0253-3219.2020.hjs.43.090101
Abstract126)   HTML7)    PDF(pc) (2637KB)(74)       Save
Background

The rapid development of small-angle scattering of X-ray (SAXS) has massively increased the speed of experiments to be performed and produced a large amount of raw data collected during each experiment. Although some software can available for batch processing, there are some difficulties in batch processing for deluged raw data, and there is no domestic batch processing available before.

Purpose

This study aims to develop a package for single and batch processing to pre-analyze SAXS/WAXS patterns and the deluge data.

Methods

Based on MATLAB platform, a semiautomatic data processing program PreSAXS 1.0 was implemented. It composed of four main capabilities: background subtraction, beam-center determination, sample-to-detector distance (SDD) calibration and the one-dimensional integrated intensity curves obtaining from deluged two-dimensional patterns. A comprehensive standard database was developed for fast indexing, and the circle fitting method was used to simulate the scattering/diffraction rings to find beam-center and calibrated SDD. The interpolation method from MATLAB was embedded in the package to improve the calculation speed.

Results

The beamcentre find, SDD calibration, and I-q curves are perfectly appropriate to Irena, Raw software. After pre-data analysis, the data are saved as ASCII code and can be used for director read or further analysis by other software.

Conclusions

PreSAXS 1.0 is easy to operate with user friendly interface, satisfies majority requirements of batch processing for SAXS data pre-analysis. However, PreSAXS 1.0 still needs to be improved, such as function extension, faster calculation speed and data analysis for GISAXS, etc.

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The effect of scram rod drop time on the consequences of molten salt reactor reactivity insertion transient
Kai WANG, Xiaowei JIAO, Qun YANG, Yanhua WANG Chaoqun WU, Zhaozhong HE
Nuclear Techniques    2020, 43 (9): 90606-090606.   DOI: 10.11889/j.0253-3219.2020.hjs.43.090606
Abstract125)   HTML2)    PDF(pc) (1823KB)(65)       Save
Background

The scram rod drop time is an important parameter for reactor safety analysis, which is of great significance to the safety of molten salt reactor (MSR). The process and the consequences of the design basis events of the MSR will be significantly influenced by the dropping time of scram rod.

Purpose

This study aims to analyse the effect of the scram rod drop time on the consequences of MSR reactivity insertion transient.

Methods

First of all, the RELAP-MS based RELAP5-TMSR (reactor excursion and leak analysis program-thorium molten salt reactor) code was employed to establish the safety analysis model for the transient simulation of TMSR-LF. Then, the sensitivity of control rod withdrawal speed to transient consequences was analyzed, next, reactivity introduction event caused by the withdrawal of a control rod at full power was taken into account to analyse the vartions of power, temperatures of fuel salt and structure materials. Influence of scram rod dropping time in emergency shutdown on transient consequences of reactivity introduction in MSR was analyzed.

Results

Even if the scram rod drop time reaches as long as 10 min, the maximum temperature of Harrington alloy is 708.2 °C, and the maximum temperature of fuel salt is 709.2 °C, which is below the safety limit.

Conclusions

The molten salt reactor has good safety characteristics, low requirements for scram rod drop time, and the ability to deal with reactivity insertion event.

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Design of moderator for boron neutron capture therapy based on D-D neutron source
Yi GONG, Xingcai GUAN, Qiang WANG Tieshan WANG
Nuclear Techniques    2020, 43 (9): 90303-090303.   DOI: 10.11889/j.0253-3219.2020.hjs.43.090303
Abstract124)   HTML6)    PDF(pc) (1750KB)(86)       Save
Background

Boron neutron capture therapy (BNCT) is a promising targeted cancer radiotherapy. The neutron source is pivotal to BNCT. The epithermal neutron flux is one of crucial characteristics for the BNCT neutron source. Therefore, in order to evaluate the quality of the BNCT neutron source, neutron flux detectors have been developed to measure the epithermal neutron flux accurately in our previous work.

Purpose

This study aims to design a moderator for the D-D neutron source for evaluating the performances of the developed BNCT neutron flux detectors.

Methods

The MCNP5 (Monte Carlo N Particle Transport Code, version 5) was employed for the BNCT moderator design based on the D-D neutron source. First of all, the neutron spectrum of a D-D neutron source passing through a single-layer moderating material with different thickness was simulated. Then combined calculation was carried out for three moderator layers configured by different materials with various thickness.

Results

A suitable configuration of the BNCT moderator based on the D-D neutron source is obtained, that is, the combination of 5 cm thick polyethylene (PE) layer + 24 cm thick titanium trifluoride (TiF3) layer + 22 cm thick magnesium fluoride (MgF2) layer is adapted as the moderator material, 20 cm thick nickel (Ni) layer is employed as the reflector and 0.03 cm thick cadmium (Cd) sheet is used as the thermal neutron filter.

Conclusions

The moderated neutron beam can be used to evaluate the performances of the developed BNCT neutron flux detectors.

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A random signal emulator for silicon drift detector based FPGA
Nian YU, Yupeng XU, Jia HUO, Yong CHEN, Weiwei CUI, Wei LI, Ziliang ZHANG, Dawei HAN, Yusa WANG, Can CHEN, Yuxuan ZHU, Xiaofan ZHAO
Nuclear Techniques    2020, 43 (8): 80402-080402.   DOI: 10.11889/j.0253-3219.2020.hjs.43.080402
Abstract121)   HTML5)    PDF(pc) (2117KB)(60)       Save
Background

The enhanced X-ray Timing and Polarimetry mission (eXTP) is a space science mission designed to study fundamental physics under extreme conditions of density, gravity and magnetism. The spectroscopic focusing array (SFA) is one of eXTP's four payloads, and its main function is to achieve spectrum and timing measurements with high dynamic range and high signal-to-noise ratio (SNR). The SFA uses multi-pixel silicon drift detector (SDD) as the focal plane detector.

Purpose

This study aims to design an SDD signal emulator for the performance test of SFA readout electronics.

Methods

The field programmable gate array (FPGA) was used as the core device of this emulator, making use of its abundant programmable logic resources to generate multiple groups of oscillatory loops. First of all, the configurable logic blocks inside the FPGA were designed as multiple oscillating rings, and its outputs were XOR-ed as true random numbers generator (TRNG). By Bernoulli trials, the uniform random numbers were converted into exponential pulse sequence. Then, the NIST (National Institute of Standards and Technology) suite was employed to test the quality of the TRNG output. Finally, the time interval distribution and counting rate characteristic of output pulses for the emulator were tested.

Results

The sequence of true random numbers of 1 000 Mbits have passed the NIST randomness test. The time interval of the output pulses for the emulator follows the exponential distribution. The dynamic range of counting rate is 1.6 ks-1 to 813.8 ks-1. The voltage range of the output pulse is 2.5 mV to 50 mV, and the minimum time interval is 9.6 ns. The signal emulator can work steadily for a long time.

Conclusions

The SDD signal emulator proposed in this paper can meet the requirements of performance tests for the SFA readout electronics.

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Synchrotron radiation photoemission spectroscopy study on the phenomenon of alloying during stanene growth
Lei ZHAO, Chen LIU, Xiaoning WANG, Gholam Turghunjan, Jinmei LI, Jiali ZHAO, Yuxuan GUO, Haijie QIAN, Ibrahim Kurash, Jiaou WANG
Nuclear Techniques    2020, 43 (7): 70102-070102.   DOI: 10.11889/j.0253-3219.2020.hjs.43.070102
Abstract119)   HTML6)    PDF(pc) (2813KB)(77)       Save
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Research and application of neutron resonance in medium-heavy nuclei
Xianguo TUO, Fule LIU, Qibiao WANG, Chao DENG, Rui SHI, Keliang MU, Jiang NIU
Nuclear Techniques    2020, 43 (10): 100201-100201.   DOI: 10.11889/j.0253-3219.2020.hjs.43.100201
Abstract116)   HTML3)    PDF(pc) (2206KB)(58)       Save
Background

Neutrons play an important role in nuclear detection applications, and make up for the shortcomings of X-ray detection insensitivity to the atomic number. In a specific energy range, the cross section of neutron reaction varies drastically with the neutron energy, and resonance occurs. The resonance spectrum of nuclides is unique, and qualitative and quantitative analysis of nuclides can be carried out based on this. Among them, the resonance energy range of medium-heavy nuclei is in the eV~keV energy range, which is an important part of neutron resonance analysis.

Purpose

Due to the lack of conclusive articles on neutron resonance in medium-heavy nuclei, this paper summarizes the current research on neutron resonance.

Methods

By querying a large number of journal papers and books related to neutron resonance, the theory and application of neutron resonance of medium and heavy nuclear are summarized.

Results & Conclusions

At present, there have been many research results, and they have been widely used in temperature measurement, imaging, non-destructive analysis, nuclear data measurement, and other aspects. In this regard, by reviewing the literature and books on neutron resonance, the research status of neutron resonance at domestic and overseas are summarized and analyzed, and its development tendency is forecast.

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Development of a 4π phoswich detector for measuring radioactive inert gases
Dongdong ZHOU, Simei YOU, Jie XIN, Cuiping YANG, Wanxin WEN, Yue YANG, Baoguo ZHANG, Rensheng WANG, Ming ZHANG
Nuclear Techniques    2020, 43 (5): 50401-050401.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050401
Abstract114)   HTML13)    PDF(pc) (989KB)(73)       Save
Background

The radiation field of the radioactive inert gas generated in a nuclear power station is mainly β-γ mixed field. The phoswich detector has good ability to discriminate β and γ rays.

Purpose

This study aims to develop a set of 4π phoswich detector to accurately measure the energy spectrum of the mixed field and distinguish β-γ rays.

Methods

The phoswich detector mainly consisted of a hollow cylindrical plastic scintillator EJ-200 with layer thickness of 1 mm and a cesium iodide scintillator CsI (Tl) with side wall thickness of 20 mm overlay on the outer layer of EJ200. The two photomultiplier tubes (PMT) were placed at both end surfaces of the cylinder respectively, and coupled by using silicone oil. The DT5790 dual digital pulse shape analyzer of CAEN company and the digital pulse processing-pulse shape discrimination (DPP-PSD) were used to obtain the detector output signals, and results were processed by ROOT and MATLAB software. Finally the detector was calibrated by use 133Ba and 137Cs radiation sources.

Results & Conclusions

The β-γ signal discrimination is realized by mathematical methods in back end computer software, indicating that the detector is capable of measuring radioactive inert gas.

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Calculation and analysis of steam generation tube rupture accident source term in PWR
Yuxuan FAN, Jingyu ZHANG, Xiaodong WANG, Yixue CHEN, Qingyang GUO, Qiuying LIANG, Wenwen XIONG
Nuclear Techniques    2020, 43 (6): 60005-060005.   DOI: 10.11889/j.0253-3219.2020.hjs.43.060005
Abstract105)   HTML2)    PDF(pc) (823KB)(31)       Save
Background

When an accident occurs in a pressurized water reactor (PWR), the radioactive nuclides are released into the environment and endanger the safety of the environment and the staff. Therefore, the analysis of the radioactive source term released into the environment after the accident is critical to the radiation protection of PWR.

Purpose

This study aims to calculate and analyze the source term of the steam generation tube rupture (SGTR) accident in PWR power plant.

Methods

According to the frequency of the accident and the severity of the consquences, the accident was divided into two conditions: pre-accident the iodine peek release and accident concurrent iodine peek release. Calculation models were established for radio-nuclide migration and diffusion after accident, and the parameters of advanced pressurized water reactor AP1000 were used for calculation and verification with emphasis on the radioactivity of inert gases and volatile nuclides iodine in the environment. [Results and

Conclusions

The calculation results show that the radioactive source term calculated by proposed model in this paper is quite consistent with the design source term. The release activity of noble gas is in good agreement with the design source term under two accident conditions, but the release activity of iodine is quite different.

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Design of gas bremsstrahlung absorber at high energy photon source beamlines
Pingcheng LIU, Qiongyao LIU, Zhongjian MA, Huijie ZHANG, Mingyang YAN, Qingbin WANG
Nuclear Techniques    2020, 43 (9): 90102-090102.   DOI: 10.11889/j.0253-3219.2020.hjs.43.090102
Abstract103)   HTML4)    PDF(pc) (2408KB)(92)       Save
Background

The high energy photon source (HEPS) currently under construction in Beijing will be the brightest synchrotron radiation facilities in the world. The high energy electrons which generate the desired synchrotron radiation interact with matter (for example, residual gas molecules in the vacuum chamber), to produce a spectrum of bremsstrahlung photons with energies up to the electron energy – in HEPS 6 GeV. The bremsstrahlung is highly penetrating, and it can produce exotic reactions in any material that it strikes, leading to the production of other radiations, especially photoneutrons. The beam stops are made of either lead or tungsten of rectangular shape in order to prevent the gas bremsstrahlung when transmitting through beamline to an experimental enclosure.

Purpose

This study aims to design a new gas bremsstrahlung absorber to reduce the dose equivalent rate by simulation calculation based on the spectrum of scattered photons and photoneutrons for HEPS beamlines.

Methods

Based on the technical specification, layout and related parameters of HEPS and the first optical enclosure (FOE), Monte Carlo simulation software FLUKA was mainly utilized to investigate the gas bremsstrahlung production in HEPS straight sections. A complete treatment of electron, positron and photon interactions at energies above 100 eV were calculated for the gas bremsstrahlung generated in the HEPS storage ring straight section and the gas bremsstrahlung transmitted through the beamline and scatters from components and the radiation emanating through the hutch wall.

Results

The results show that the beam stop is effective in shielding photons, but the photoneutrons in HEPS beamlines is inevitable. The equivalent rate of neutrons outside the shield wall is still high. The maximum energy of neutrons in photonuclear reaction reaches upto 300 MeV. Giant resonance neutrons (0.1~5 MeV) account for 91% of the total flux of photoneutrons. Using polyethylene as local shield is a very effective method.

Conclusions

The combined shielding of lead and boron containing polyethylene can effectively reduce the neutron dose equivalent rate inside and outside FOE of HEPS beamlines.

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The elements and specification of 18F-FDG PET-CT and PET-MR tumor imaging report in Shanghai
Nuclear Techniques    2021, 44 (1): 10001-010001.   DOI: 10.11889/j.0253-3219.2021.hjs.44.010001
Abstract102)   HTML26)    PDF(pc) (880KB)(395)       Save
Positron emission tomography (PET) is an imaging device that can reflect biochemical metabolism in
vivo. When combined PET with X-ray computed tomography (CT) or magnetic resonance (MR), the biochemical
metabolic characteristics and pathological structure of tissues are all well represented. Compared with PET-CT, PETMR
has higher resolution for soft tissues, and shows the shape, boundary and surrounding conditions of the lesions
more clearly. More importantly, PET and MR scan synchronously, hence the scanning time is reduced, and the
radiation of CT is avoided. However, it is difficult to popularize the application of PET-MR due to its high inspection
cost. Moreover, the high magnetic field environment of MR limits its application in patients with implanted medical
devices, such as cardiac pacemaker, cochlear implant and insulin pump.
For non-nuclear medicine doctors, the examination report is the most intuitive basis for diagnosis and treatment
of patients. Therefore, it is necessary to describe the morphology of suspicious tumor and the its 18F-FDG uptake
value in the report. In order to standardize the 18F-FDG PET-CT and PET-MR tumor imaging reports, nuclear
medicine experts in Shanghai compiled the elements and specification of 18F-FDG PET-CT tumor imaging report and
18F-FDG PET-MR tumor imaging report, and presented in this paper as two complete specification reports
independengly. More details for each report template and sample download link address are provided for reference.
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Analysis and optimization of flow distribution for the reactor core of China initiative accelerator driven system
Jun WEN,Tianji PENG,Xukai FAN,Dajun FAN,Wangsheng TIAN,Dawei WANG,Long GU
Nuclear Techniques    2020, 43 (7): 65-74.   DOI: 10.11889/j.0253-3219.2020.hjs.43.070601
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Background

Flow rate distribution is a significant study object in the reactor core design of China initiative accelerator driven system (CiADS). Reasonable flow rate distribution will ensure reactor core work safely.

Purpose

This study aims to optimize flow distribution in the coolant inlet area of each fuel assembly of CiADS so that the outlet temperature distribution is flat.

Method

Firstly, the top and bottom nozzle flow field were calculated by computational fluid dynamics (CFD) software. Secondly, based on the above results, the porous media model was employed to establish the flow and heat transfer analysis model of the whole reactor for numerical simulation of the flow distribution in the core, and the power coefficient was used as the reference for reactor core flow distribution.

Results

These calculation results show that the flow distribution and power coefficients are almost consistent, and the outlet temperature distribution for the fuel assemblies has been flattened. Both the pressure drop characteristics and coefficient of resistance properties of the top and bottom nozzle obtained by simulation provide the necessary parameters for analyzing the flow distribution of the core.

Conclusions

Based on the calculations, the coolant inlet area of each fuel assembly has been optimized. These calculation results show that the flow distribution and power coefficients are almost consistent, and the outlet temperature distribution for the fuel assemblies has been flattened. Thus, the fuel assembly could be operated under the safety conditions. Meanwhile, these results can provide some reference data for the subsequent hydraulic analysis.

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Neutron capture cross section measurement of 197Au with pulse height weighting techniques
Xinxiang LI, Longxiang LIU, Wei JIANG, Jie REN, Hongwei WANG, Gongtao FAN, Xiguang CAO, Xinrong HU, Yue ZHANG, Junwen WANG, Zirui HAO, Bing JIANG, Xiaohe WANG, Jifeng HU, Jincheng WANG, Dexin WANG, Suyalatu ZHANG, Yingdu LIU, Xu MA, Chunwang MA, Yuting WANG, Zhendong AN, Jianjun HE, Jun SU, Liyong ZHANG
Nuclear Techniques    2020, 43 (8): 80501-080501.   DOI: 10.11889/j.0253-3219.2020.hjs.43.080501
Abstract94)   HTML4)    PDF(pc) (2184KB)(35)       Save
Background

Pulse height weighting technology is a data processing method for measuring neutron capture cross section with C6D6 detector.

Purpose

This study aims to measure the neutron capture cross section of 197Au on the back-n target station of China spallation neutron source (CSNS) by using Pulse height weighting technology, and verify the feasibility and data processing of this method.

Methods

First of all, detection efficiency of the detector, the pulse height weighting function of C6D6 and other basic terms under different target conditions were simulated by Geant4 Monte Carlo code, so that the weighted detector efficiency was proportional to the gamma energy. Then experimental measurement of neutron capture cross section of 197Au was carried out by the Au target calibration data in the experiment.

Results & Conclusions

The experimental results show that the measured neutron capture cross section data are consistent with the ENDF/B-VIII.0 evaluation data. Inconsistent size of the carbon target and the sample target, and the increase of the proton beam power will cause a large error in the background subtraction.

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Research on pulsed laser heating method applied in high-pressure XRD measurement
Weiran CUI, Xiaodong LI, Yu GONG, Yanchun LI, Dongliang YANG, Junran ZHANG, Yixuan XU
Nuclear Techniques    2020, 43 (8): 80101-080101.   DOI: 10.11889/j.0253-3219.2020.hjs.43.080101
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Background

Compared with the traditional continuous-wave laser heating method, the pulse laser heating (PLH) technology can minimize the heating time to prevent the potential chemical reactions in the sample chamber of diamond anvil cell.

Purpose

This study aims to construct an in-situ pulsed laser heating method which can be applied in high pressure X-ray diffraction experiments.

Methods

Based on the continuous-wave laser heating system of the high-pressure beamline of Beijing synchrotron radiation facility (BSRF), a signal generator was used to synchronize the pulsed laser, charge coupled device (CCD) spectrometer and X-ray detector, made it capable to heat the sample with pulsed laser, and collect the thermal radiation spectrum and high-pressure diffraction data during heating. The temperature stability, repeatability and temperature gradient of Pt samples heated by pulsed laser under high pressure were measured, and the in-situ X-ray diffraction experiments were completed by using the cumulative time method.

Results

Experimental results show that the axial temperature gradient is larger when the temperature is low, but decreases with the increase of temperature. The PLH high-pressure XRD experimental data of Pt with good quality are collected by using the in-situ X-ray diffraction patterns.

Conclusions

The in-situ PLH method for high-pressure X-ray diffraction experiments enables the pulsed laser to have heating ability at the high-pressure beamline of BSRF, and lays a foundation for the future research on the application of related methods at the new High Energy Photon Source (HEPS) in Beijing.

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Proposal for X-ray vortices production based on nonlinear laser Compton scattering
Heping GENG, Hailong WU, Jianhui CHEN, Zhentang ZHAO
Nuclear Techniques    2020, 43 (7): 70201-070201.   DOI: 10.11889/j.0253-3219.2020.hjs.43.070201
Abstract92)   HTML1)    PDF(pc) (1463KB)(72)       Save
Background

An optical vortex is an electromagnetic wave with a phase that varies azimuthally along the direction of propagation. The generation and application research of X-ray vortices are becoming more and more popular in recent years.

Purpose

This study aims to propose a generation scheme of a compact and inexpensive X-ray vortices source based on nonlinear laser Compton scattering (LCS).

Methods

Laser Compton scattering (LCS) was caused by high power circularly polarized light and relativistic electron beam. This LCS provided a practical method for generating tunable, near-monochromatic, well-collimated X-rays in a compact, relatively inexpensive source.

Results

Photons with energy of 1 keV is produced by head on nonlinear LCS interaction of 6.5 MeV electron beam and 800 nm Ti: Sapphire laser beam.

Conclusions

Compared with synchrotron, X-ray vortices source based on nonlinear LCS is a compact and inexpensive source. It provides a practical method for the laboratory to research the generation and application of X-ray vortices.

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Improvement and performance analysis of cusp-like pulse shaping algorithm
Xinyang FAN, Min WANG, Xu HONG, Tibo YANG, Guanghui LIAO, Zhouxuan OUYANG
Nuclear Techniques    2021, 44 (1): 10402-010402.   DOI: 10.11889/j.0253-3219.2021.hjs.44.010402
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Background

Digital shaping algorithms are widely applied to improving the energy resolution of digital nuclear instruments.

Purpose

This work aims to improve and analyze the performance of cusp-like shaping algorithm for digital nuclear signal with emphasis on the influence of shaping parameters on the shape of the shaped pulse.

Methods

Based on the peak pulse forming algorithm, flat-top parameter was introduced into cusp-like pulse shaping algorithm. The fast silicon drift detector (FAST-SDD) detector produced by Amptek company was employed to measure the pulse signal obtained from manganese sample, the effect of shaping parameters on the shape of the output signal and the separation of pile-up pulses were investigated by the cusp-like pulse shaping method, and compared with the common trapezoidal pulse shaping methods. In addition, Cusp-like shaping and trapezoidal pulse shaping were used for the sampled nuclear pulse signals, and then amplitude discrimination was performed to obtain energy spectrum information. Finally, the influences of the two methods on the counting rate and energy resolution of the same time were studied.

Results

The results show that the cusp-like pulse shaping has a fast falling edge and a narrow pulse width, makes it easier to separate the pile-up pulses than triangle pulse shaping.

Conclusions

Under the same peak time, trapezoidal pulse shaping has more advantages in energy resolution than cusp-like shaping, while cusp-like pulse shaping shows better performance in count rate.

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Research on application of time-varying tune calculation algorithms on SSRF
Xing YANG,Longwei LAI,Fangzhou CHEN
Nuclear Techniques    2020, 43 (12): 120101-120101.   DOI: 10.11889/j.0253-3219.2020.hjs.43.120101
Abstract91)   HTML5)    PDF(pc) (2671KB)(28)       Save
Background

Tune is one of the most important characteristic parameters of storage ring, it seldom changes over time, hence can be obtained by a simple harmonic analysis on the beam position data. In some particular process, tune will change with time.

Purpose

This study aims to explore and optimize the time-varying tune calculation algorithms for the tune drift caused by the nonlinear effect of Lattice during the decay of the residual transverse oscillation damping, after the injection of the storage ring.

Methods

First of all, the applicability of the wavelet algorithm and numerical analysis of fundamental frequencies (NAFF) algorithm for time-varying tune calculation was analyzed, and their performances were on above physical process of nonlinear effect of the storage ring were compared. Then the better Morlet wavelet algorithm was employed to quantitatively analyze the drift of tune during the injection of the Shanghai Synchrotron Radiation Facility (SSRF) storage ring and evaluate the nonlinear intensity changes of the SSRF during different operating period.

Results

Algorithm comparison results show that both algorithms can realize the dynamic analysis of time-varying tune, but the wavelet method shows better performance. Evaluation results of nonlinear strength change of SSRF storage ring show that when the data analysis window is selected as 6 000 cycles, a track offset change 0.3 mm, and tune change as small as 0.000 1 can be detected. During the period of storage ring injection, the tune changes obviously.

Conclusions

By applying the morlet wavelet algorithm, the complete trajectory of the tune drift can be tracked.

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Design and numerical simulation of Stirling heater for molten salt space reactor
Heng ZHAO, Yang ZOU, Ye DAI, Hongjie XU, Jie ZHANG, Fan HE
Nuclear Techniques    2020, 43 (10): 100601-100601.   DOI: 10.11889/j.0253-3219.2020.hjs.43.100601
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Background

Stirling heater is used for heat capture in the molten salt space reactor power generating system, and its heat transfer performance has a great influence on the output power and efficiency of the space reactor energy conversion system.

Purpose

This study aims to improve the heat transfer performance of the heater by numerical simulation of designed fins in molten salt channel and porous Stirling internal thermal receiver.

Methods

The computational fluid dynamics program Fluent was employed to design and optimize the structure of the heater. Thermal-hydraulic characteristics of different fins and molten salt channel types, such as flow field, pressure field and heat flux distribution were simulated and compared.

Results

Adding fins in the molten salt channel can improve the heat transfer performance of the Stirling heater, and with the increase of fin height and the decrease of fin spacing, the heat transfer performance further improves. Compared with radial inlet and tangential inlet, the double-radial inlet and outlet channels have more uniform heat flux distribution and better heat transfer performance.

Conclusions

The results of this study provide useful references for the design of the Stirling heater in molten salt space reactor.

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Neutronics analysis of commercial pressurized water reactor loaded with FCM fuel
Xue QIN, Mancang LI, Hongkuan LIAO, Yingrui QIN Dong YU, Zhumin JIANG, Shuai WANG, Yun CAI, Rui GUO
Nuclear Techniques    2020, 43 (8): 80007-080007.   DOI: 10.11889/j.0253-3219.2020.hjs.43.080007
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Background

During the Fukushima accident, the shortcomings of the existing UO2-zirconium alloy fuel form in resisting severe accidents were exposed. Fully ceramic microencapsulated fuel (FCM) disperses tri-structural iso-tropic (TRISO) fuel particles in a SiC matrix and has the ability to contain fission products, hence can effectively improve the ability of nuclear fuel to maintain structural integrity under severe accidents. FCM fuel can reduce the risk of large quantities of radioactive materials leakage in nuclear power plants, it is one of the main research objects of accident tolerant fuel (ATF). Compared with the traditional UO2 ceramic fuel pellets, the U loading of FCM fuel has better moderation ability and less U loading. When the FCM fuel is used in a commercial pressurized water reactor (PWR), it may cause the positive moderator temperature coefficient (MTC) and loss of inherently safety of the core.

Purpose

This study aims to analyse the neutronics characteristics of commercial PWR using FCM fuel from the perspective of inherent safety and economy.

Methods

The UO2-Zr alloy fuel assemblies in the form of standard AFA3G 17×17 grid were taken as reference objects. The NESTOR software independently developed by China national nuclear corporation (CNNC) was employed to analyse the neutron characteristics of FCM fuel (UN core) assembly in forms of 17×17 grid and 13×13 grid. The overall physical performances of the reactor core composed of FCM fuel (UN core) in the form of a 13×13 grid were evaluated.

Results

Computational results show that FCM fuel (UN core) assembly in the form of 13×13 grid containing gadolinium poisons meets the requirements of under moderation, and the FCM fuel (UN core) assembly in the form of 13×13 grid can be adapted by large commercial PWR with negative MTC at the initial stage while the fuel consumption depth and cycle length of the first cycle core are basically equivalent to those of the reference core.

Conclusions

FCM fuel assemblies used in commercial PWR can initially meet the inherent security and economic requirements. Further research work will be carried out to optimize the analysis of core power flattening.

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Research on optimal design of new neutron detector based on 6Li + CdTe
Long MA, Lichao TIAN, Yanyun MA, Zhongliang LYU, Peng HAN, Meng PENG, Xiaohu YANG, Guobo ZHANG, Xiaoxiao LI, Fei SHAN
Nuclear Techniques    2020, 43 (8): 80401-080401.   DOI: 10.11889/j.0253-3219.2020.hjs.43.080401
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Background

Facing the internationally serious shortage of 3He gas, a novel neutron detector based on 6Li+CdTe was proposed in 2018, which has high neutron detection efficiency and low γ sensitivity, showing a good application prospect.

Purpose

This study aims to conduct an optimal design of the neutron detector based on 6Li+CdTe and explore its application to the special nuclear material monitoring system.

Methods

First, the structure and operating principle of a typical 6Li+CdTe unit was analyzed. Then the Monte Carlo simulation of MCNP6 was employed to optimize the key parameters of this detector. Finally, integrated analysis was performed using this model for the special nuclear material monitoring system.

Results

The optimal thickness of the CdTe absorption layer is 10 μm. When the number of 6Li+CdTe detection units reaches 6 layers with the optimal 6Li layer of 60 μm, the detection efficiency is more than 50%. A detector system with an area of 4 m×32 cm, surrounded by polyethylene of 3 cm in the front and 10 cm in the side and back, can meet the requirements of the special nuclear material monitoring system.

Conclusions

The novel neutron detector with optimal design can be used as the alternative of 3He based neutron detector in the special nuclear material monitoring system.

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Placement scheme of burnable poisons in a small modular fluoride-cooled high temperature reactor
Sijia LIU, Guifeng ZHU, Rui YAN, Yang ZOU, Hongjie XU
Nuclear Techniques    2020, 43 (5): 50602-050602.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050602
Abstract87)   HTML3)    PDF(pc) (1569KB)(33)       Save
Background

Small modular fluoride-cooled high temperature reactor (SM-FHR), with inherent safety and high temperature output ability, will accelerate the diversified development of world energy and meet the demand of comprehensive utilization of energy.

Purpose

This study aims to simplify the reactivity control of SM-FHR, one of the key design goals, by using burnable poisons of boron carbide to lower the excess reactivity of SM-FHR.

Methods

Based on the SM-FHR design model, burnup code MOBAT was used to analyze the excess reactivity curves under different loads, different particle sizes and different space distribution of burnable poisons in fuel compacts.

Results

Calculation results show that an optimal scheme exists when volume ratio of fuel to burnable poison (F/P) is 52, and particle size is 200 μm with lower loading in some outer assembles. Its excess reactivity is reduced from 38 000 ×10-5 to 2 500 ×10-5, and the power peak factor after layout of burnable poisons is only 1.26. The burnup time is decreased, but it still meets refueling cycle expectation for more than 2 full power years.

Conclusions

The layout scheme of burnable poisons proposed in this paper makes the core burnup depth and power distribution flattened, hence improving the core safety.

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Analysis of Th-U breeding in molten salt fast reactor
Dongguo LI, Guimin LIU
Nuclear Techniques    2020, 43 (5): 50604-050604.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050604
Abstract86)   HTML3)    PDF(pc) (2012KB)(59)       Save
Background

Because of its superior performance, molten salt reactor has been selected as one of the candidates for the fourth-generation reactors, and has become the focus of international attention.

Purpose

In the molten salt fast neutron reactor, we try to find the most suitable molten salt fuel scheme to achieve the purpose of high proliferation of fissile nuclides.

Methods

Based on the two-fluid cooling cycle scheme, independent cooling cycles of fission molten salt fuel and breeding molten salt, a comprehensive simulation program SCALE (Standardized Computer Analyses for Licensing Evaluation) was employed to achieve high breeding ratio (BR) in the molten salt fast reactor by utilizing the high solubility characteristics of thorium and uranium heavy metal salts in fluorinated or chlorinated molten salts at high temperatures. Three feasible molten salt fuel schemes (LiF+ThF4+UF4, NaF+ThF4+UF4, and NaCl+ThCl3+UCl3) were compared by calculating the neutron energy spectrum and the reactivity temperature coefficient. Influence factors of BR, such as the sizes of fission zone, breeding zone and ZrC reflective layer, the isotopic abundance of 6Li and 35Cl in the molten salt, molten salt density error on the calculation accuracy, and the evolution of fissile nuclides with reactor operating time, were computationally analyzed.

Results

The breeding ratio (BR) of reactor reaches about 1.2 in all three molten salt fuel schemes when the diameter and height of the fission zone are both 260 cm.

Conclusions

With optimization of the reactor geometry, and the composition and isotopic abundance of the molten salt fuel, a high breeding ratio of the reactor is achievable for the thorium-uranium fuel cycle of molten salt fast reactor.

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Research on beam-base alignment for 120 MeV electron linear accelerator
Bin SUN, Yu WANG, Dongwei HEI, Binkang LI, Xinjian TAN, Xiufeng WENG, Jun LIU, Xiaodong ZHANG, Zhuming FU
Nuclear Techniques    2020, 43 (6): 60202-060202.   DOI: 10.11889/j.0253-3219.2020.hjs.43.060202
Abstract86)   HTML1)    PDF(pc) (1273KB)(50)       Save
Background

120 MeV electron linear accelerator has high requirement for beam emittance, and the traditional optical collimation cannot meet the requirement.

Purpose

This study aims to use beam-based alignment (BBA) method to achieve higher precision collimation and obtain better beam quality.

Methods

According to the configuration of 120 MeV electron linear accelerator, all of beam position monitor (BPM) measurement data of the corresponding position under different energy were collected, then, the dispersion-free steering (DFS) algorithm was used to simulate the correction of accelerator matching transmission section in different beam jitter conditions.

Results

The simulation results indicate that the algorithm can minimize the transverse offset of quadrupole to 50 μm.

Conclusions

The DFS algorithm can reduce the trajectory distortion in the low beam jitter accelerator.

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Preliminary neutronics design of space nuclear reactor based on molten salt cooling
Ting LI, Kun ZHUANG, Wen SHANG, Xiaobin TANG
Nuclear Techniques    2020, 43 (8): 80006-080006.   DOI: 10.11889/j.0253-3219.2020.hjs.43.080006
Abstract86)   HTML1)    PDF(pc) (1499KB)(31)       Save
Background

Space nuclear reactor (SNR) has attracted more and more attention worldwide due to its significant advantages in deep space exploration. Different from the traditional liquid metal, gas and heat pipe cooling methods, molten salt coolant can dissolve fission materials with good heat transfer properties, hence can be used as a coolant in SNR scheme.

Purpose

This study aims at the preliminary neutronics design for molten salt cooled SNR.

Methods

Based on the design scheme of SNR, Monte Carlo code SERPENT and database ENDF/B-Ⅶ.1 were employed for preliminary neutron design of SNR with molten salt cooling. The effects of different fuel, cladding materials, rod pitch on the kinf of fuel rods and effects of different molten salts, reflector materials on the keff of core were investigated. Finally, a preliminary SNR core scheme based on fluoride salt 7LiF-BeF2-UF4 (66.4-32.7-0.9 mol%) to cool UC fuel (235U, mass fraction at 80%) was proposed.

Results

The results show that keff of fuel rods is closely related to the fuel material, it increases with the 235U enrichment of fuel and decreases with the rod pitch.

Conclusions

Different molten salts and reflector materials have great influences on keff of reactor core, but the 235U enrichment of UF4 in coolant is not sensitive to keff.

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Analysis of U-Pu breeding in molten salt fast reactor
Dongguo LI, Xuemei ZHOU, Guimin LIU
Nuclear Techniques    2020, 43 (8): 80003-080003.   DOI: 10.11889/j.0253-3219.2020.hjs.43.080003
Abstract86)   HTML2)    PDF(pc) (1886KB)(40)       Save
Background

Molten salt reactor has been selected as one of the candidates for the fourth generation reactors due to its superior performance, and molten salt fast reactor has become one of the hot research subjects in the world.

Purpose

This study aims to find the most suitable molten salt fuel scheme in the uranium-plutonium cycle to achieve the purpose of high proliferation of fissile nuclides.

Methods

Based on the two-fluid cooling cycle scheme, independent cooling cycles for fission molten salt fuel and breeding molten salt, a comprehensive simulation program SCALE (Standardized Computer Analyses for Licensing Evaluation) was employed to calculate the neutron spectrum and reactivity temperature coefficient of three feasible molten salt fuel schemes (LiF+PuF4+UF4, NaF+PuF4+UF4 and NaCl+PuCl3+UCl3). High breeding ratio (BR) in the molten salt fast reactor was realized by utilizing the high solubility characteristics of plutonium and uranium heavy metal salts in fluorinated or chlorinated molten salts at high temperatures. Influence factors of BR, such as the sizes of fission zone, breeding zone and ZrC reflection layer, the isotopic abundances of 6Li and 35Cl in the molten salt, as well as the dynamic change of BR with running time, were computationally analyzed.

Results

The BR of two fluorinated molten salt schemes reaches about 1.06 whilst BR of the chlorinated molten salt scheme reaches 1.46 when the diameter and height of the fission zone are both 260 cm.

Conclusions

Combined with the phase diagram of molten salt, the variation curve of BR with the molar concentration of heavy metals and the variation curve of the maximum value of BR with the average operating temperature of molten salt, the operating temperature of molten salt, the molar concentration of heavy metals and the reactor BR can be be quickly determinated in the conceptual design of the molten salt fast reactor.

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Automatic calibration system of small angle X-ray scattering experiment station at SSRF
Chunxia HONG, Ping ZHOU, Wenqiang HUA, Chunming YANG, Fenggang BIAN
Nuclear Techniques    2021, 44 (1): 10102-010102.   DOI: 10.11889/j.0253-3219.2021.hjs.44.010102
Abstract84)   HTML5)    PDF(pc) (1458KB)(50)       Save
[Background]

The quality of the experimental data is closely related to the optimal optical conditions of the end-station in the small-angle X-ray scattering (SAXS) beamline (lower scattering background, accurate beam intensity before and after the sample, etc.). At present, the optical conditions of the end-station are manually optimized in SAXS beamline (BL16B1) of shanghai synchrotron radiation facility (SSRF), which can not utilize the user's time effectively.

Purpose

This study aims to design and implement an automatic calibration procedure with Python on the platform of EPICS (experimental physics and industrial control system) and CSS (control system studio).

Methods

Firstly, the direct beam was searched and targeted using slit blades scanning, and then beam center was automatically optimized according to the single-objective and multi-objective optimization methods of genetic algorithm, the calibration is not completed until an optimal scattering background image is obtained.

Results

The results show that the automatic beamline calibration system can complete the motors optimization of slits and beamstop in 30 min, much faster than manual operation.

Conclusions

Proposed automatic calibration system simplifies the optical path optimization of experimental station and improves the automation of the SAXS beamline station at SSRF.

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Analysis of Th-U and U-Pu fuel cycle in a 2 500 MWth molten chloride salt fast reactor
Xiaoxiao LI, Chenggang YU, Yuwen MA, Xiangzhou CAI, Jingen CHEN, Xingwei CHEN
Nuclear Techniques    2020, 43 (11): 110601-110601.   DOI: 10.11889/j.0253-3219.2020.hjs.43.110601
Abstract83)   HTML2)    PDF(pc) (1492KB)(26)       Save
Background

The molten chloride salt fast reactor (MCFR) has advantages of high solubility of nuclear fuel and fast neutron spectrum, which makes it possible to achieve high breeding and transmutation efficiency.

Purpose

This study aims to investigate the neutronics characteristics of Th-U fuel cycle and U-Pu fuel cycle in a 2 500 MWth MCFR, including the critical characteristic, burnup evolution, and breeding and transmutation performance.

Methods

The 233U and 239Pu were used as ignition fuels of Th-U fuel cycle (U3+Th) and U-Pu fuel cycle (Pu9+DU) respectively, and their fertile materials were 232Th and depleted uranium (DU), correspondingly. The analysis of the transition modes TRU+Th and TRU+DU with TRU as ignition fuel are also introduced.

Results

Considering the neutron absorption rate of actinides, neutrons produced per fission (ν) and the conversion ratio (CR), nuclear fuel cycle mode of U3+Th needs a variable feed of fissile fuel to maintain the critical operation of the core, whereas Pu9+DU, TRU+DU and TRU+Th can be operated for a long time without on-line refueling, that is 46 a, 50 a and 29 a, respectively.

Conclusions

TRU+Th fuel cycle mode is promising to MCFR due to its high self-sustaining breeding and high effective transmutation.

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Research on the influence of slope error on free-electron laser focusing spot
Ximing ZHANG, Zhi GUO, Xiangyu MENG, Xiangzhi ZHANG, Zuanming JIN, Yong WANG
Nuclear Techniques    2020, 43 (6): 60101-060101.   DOI: 10.11889/j.0253-3219.2020.hjs.43.060101
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Background

The self-amplified spontaneous emission (SASE) free-electron laser beamline, dedicated for live-cell imaging, is under construction in the Shanghai soft X-ray free-electron facility. The energy range of the beamline is from 100 eV to 1 000 eV and the beamline covers two branch lines, including frontend, attenuator, plane mirror PM1, variable-line-spacing grating PM2, monochromator, bendable mirror, Kirkpatrick-Baez (KB) mirrors and ellipsoidal mirror etc. The Kirkpatrick-Baez mirrors of the north branch line consisting of a plane mirror and two elliptical cylinder mirrors are used for biological-cell imaging. The surface of mirrors should be highly reliable and precise in the system of the free-electron laser beamline. Slope error of optical elements during the production processing is an important criterion for measuring the surface quality of optical elements. The slope error of mirror is associated with the height error, and affects the coherent and wavefront of the beam, and further affects the final light spot.

Purpose

This study aims to explore the variation of the slope error on X-ray coherent and wavefront after propagating in the beamline, and choose appropriate mirror whose slope error has little influence on the beam.

Methods

The software SHADOW and SRW were employed for the simulation to trace the X-ray propagation in the KB mirror and the whole beamline.

Results

When the slope error of plane mirrors is controlled between 0.1 μrad and 0.2 μrad, the slope error of elliptical cylinder mirrors is less than 0.4 μrad, and the height error is approximately 3 nm, the high-quality image with spot size less than 4 μm is obtained, satisfying the imaging needs of biological imaging experimental station.

Conclusions

Results of this study provide comprehensive detailed data for the optimal design of soft X-ray free-electron laser beamline.

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Irradiation demagnetization of permanent magnets in insertion device for high-energy synchrotron radiation light source
Pingcheng LIU, Qiongyao LIU, Zhongjian MA, Huijie ZHANG, Mingyang YAN, Qingbin WANG
Nuclear Techniques    2020, 43 (10): 100101-100101.   DOI: 10.11889/j.0253-3219.2020.hjs.43.100101
Abstract82)   HTML11)    PDF(pc) (1227KB)(35)       Save
Background

In synchrotron radiation facilities, the insertion devices are installed on the storage ring to produce high brightness, high coherence, and adjustable polarization synchrotron radiation, which are composed of periodic permanent magnet arrays. The permanent magnets are continuously exposed to beam loss electrons due to the Touschek effect. As a result, the permanent magnets can be more or less damaged and deteriorates the magnetic field of insertion devices. Radiation-induced demagnetization of permanent magnets in the insertion device is one of the critical issues for synchrotron radiation facilities.

Purpose

This study aims to simulate the irradiation field and radiation damage of the Nd2Fe14B permanent magnet insertion devices during the routine operation of the high energy photon source (HEPS).

Methods

First of all, Monte Carlo code FLUKA was utilized to calculate the relationship between the absorbed dose and demagnetization of Nd2Fe14B magnet array based on the Spring-8 experiment. Then the different electronic sampling modes were set to calculate the irradiation field in the insertion device according to the actual beam loss conditions at HEPS. Finally, the demagnetization and countermeasures were analyzed according to the spatial distribution of absorbed dose.

Results

When HEPS works in top-up mode, the irradiation of the magnetic pole in the upstream end of the insertion device is more severe. Most of the absorbed dose (about 99.7%) is contributed by photon, electron and positron. According to the beam loss parameters by physical calculation, the expected life of the insertion device is 2.1 to 4.6 years.

Conclusions

Placing local shielding layer and increasing the gap are the effective measures to protect the insertion devices, hence slow down radiation demagnetization of permanent magnet.

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