最新刊期
卷 39 ， 期 10 ， 2016
- 摘要：Background X-ray is widely used in various industries whilst the filament power supply is an important core component of X-ray tube. Traditional technology that applies 220-V AC input power frequency, power factor correction, the step-down transformer heating filament works fine for medium and large X-ray tube filament power supply, but is unsuitable for the micro X-ray tube. Purpose This study aims to develop a novel filament power supply for practical micro X-ray tube. Methods According to the characteristics of the micro X-ray tube, the push-pull circuit and a closed-loop feedback circuit were employed for the filament drive power supply. UCC3808 pulse width modulation (PWM) control chip was used to generate two opposite phase PWM signals, and the driving efficiency was improved through the UCC37324 metal-oxide-semiconductor (MOS) tube high current drive, so as to achieve the back-end of push-pull driving circuit. The tube current signal was converted into isometric voltage signal through the precision resistor, and then be introduced into the feedback loop through closed-loop control of the system to achieve a constant tube current, and maintain high efficiency and low power consumption. Results The input power is measured to be 11W, and efficiency to be more than 80% when firstly connected to a 1.5-Ω power resistance, which meets the power consumption requirements of the filament power supply. Then an actual X light tube filament was connected for practical test, results show it is in working order with tube flow stability of 0.227%.Conclusions: The filament power supply proposed in this paper meets the requirements of practical micro X-ray tube, its stability is mainly induced by the ripple of high voltage power on the filament, and the unoptimized parameters of tube flow closed-loop feedback loop. These will be improved in the future work.关键词：Micro X-ray tube;Filament power supply;Push-pull circuit;Tube current closed-loop feedback circuit
- 34
- |
- 12
- |
- 1
发布时间：2021-05-24
Nuclear Electronics and Instrumentation
- 摘要：Background:GaAs is widely used as the second generation semiconductor material in the fields of aerospace and radiation detection. Purpose:Study of the irradiation effects of GaAs is of guiding significance for the evaluation of the radiation resistance of GaAs devices. Methods:Semi-insulating GaAs were irradiated by 250-keV H+ and 4.5-MeV Kr17+ ions with fluences ranging respectively from 1×1012 cm-2 to 3×1014 cm-2 and 3×1011 cm-2 to 3×1014cm-2. Photoluminescence (PL) spectrum and Raman scattering spectra were used to measure GaAs samples before and after irradiation. Results:PL spectrum shows that the intensity of CAs peaks and phonon replicas decrease with increasing fluence of H+ irradiation. The IGa-VAs peak in 913 nm was increased at lower fluence and decreased at higher fluences. But all the peaks completely disappeared with Kr17+ irradiation. The results of Raman spectra show that the longitudinal-optical (LO) phonon peak at 295-cm-1 slides towards the low-frequency side and broadens its width asymmetrically by Kr17+ irradiation, while it has no obvious change by proton irradiation. Conclusion:The difference between the effect of proton and Kr17+ irradiation is due to the difference of the displacement damage by three orders of magnitude at least. The evolution process of damage defects in GaAs is obtained by using Multi-step damage accumulation (MSDA) model, and then the trends of optical properties and crystalline structure are well explained.关键词：GaAs;Irradiation effect;Photoluminescence spectrum;Raman scattering spectra
- 34
- |
- 12
- |
- 0
发布时间：2021-05-24 - 摘要：Background:d0 ferromagnetism challenges the understanding of magnetism in insulators. MgO, which is important for magnetic tunnel junctions, is an ideal material for investigating d0 ferromagnetism. The ferromagnetism in MgO has attracted great interests. Purpose:This study aims to investigate the influence of γ-ray irradiation on point defect configurations and magnetic properties of (100)-oriented MgO single crystals. Methods:The point defect configurations in irradiated-MgO single crystals were experimentally studied using synchrotron radiation diffuse scattering and ultraviolet-visible (UV-vis) absorption spectroscopy. Based on Huang's scattering theory, the isointensity profile of diffuse scattering was calculated by MATLAB program. The magnetic properties were measured by superconducting quantum interference device (SQUID). Results:ω-2θ scans and rocking curves of (200) and (311) peaks of samples indicated generation of point defects and lattice distortion in irradiated MgO single crystals. The presence of Frenkel defects in irradiated MgO single crystals was evidenced by reciprocal space mappings around the (200) reflection and UV-vis absorption spectra. The M-H and M-T curves of irradiated MgO single crystals remained the same as that of the unirradiated, demonstrating that the magnetic properties of irradiated MgO were unchanged. Conclusion:Lots of anion vacancies are generated by γ-ray irradiation in (100) MgO single crystals. However, the anion vacancies cannot induce d0 ferromagnetism in MgO single crystals.关键词：ray irradiation;MgO single crystal;Point defect;Diffuse scattering;d0 ferromagnetism
- 26
- |
- 11
- |
- 0
发布时间：2021-05-24 - 摘要：Background:90Sr is the key monitoring object in the domestic and foreign environment because of its high fission yield and long half-life. There are mainly three methods in current standards, which are all used to measure the content of 90Y for calculating the content of 90Sr. All these methods have long experimental periods. Purpose:This study aims to build a method to detect 90Sr in biological samples rapidly and effectively and to shorten the detection period. Methods:A new 90Sr detection method in biological samples is built. And a new Sr·Spec solid phase extraction resin is used to separate and purify90Sr in this method, combined with digestion pretreatment, carbonate precipitation, low background alpha and beta measurement. Results:This method is to determine directly the content of 90Sr. The detection period was shortened obviously and the recovery of Sr was about 80%. Conclusion:Experimental results show that the new method is rapid and effective for 90Sr detection in biological samples.关键词：Biological samples;90Sr;Sr·Spec resin;Rapid;Detection
- 20
- |
- 11
- |
- 1
发布时间：2021-05-24 - 摘要：Background:Put forward the demands for low concentrations of elements in the X-ray absorption fine structure (XAFS) study on synchrotron radiation facility requires high sensitive solid state detectors. Silicon Drift Detector (SDD) is a small fluorescence detector that can be equipped with semiconductor refrigeration to achieve high count rate and high energy resolution. Its commercial products are becoming gradually mature. Purpose:This study aims to develop a small SDD based data acquisition (DAQ) system for XAFS beamline 1W2B experimental station at Beijing Synchrotron Radiation Facility (BSRF) and programmed the corresponding DAQ software for users. Methods:A XR-100FAST SDD from Amptek Inc was employed together with related electronics and ORTEC 974 counter for 1W2B experiment station. Corresponding DAQ software for user was developed using LabVIEW on the back-end control computer. CuSO4 solution containing Cu 100 mg·L-1 is prepared as a sample for testing this DAQ with SDD as detector, and Fourier transform of the radial distribution function is applied to experimental data analysis. Results:The final data shows information on the local structure of the first coordination of oxygen around Cu atoms. Conclusion:The test results of CuSO4 solution with concentration of 100 mg·L-1 proved that the new DAQ system equipped at 1W2B experimental station could satisfy the requirements of XAFS experiment fluorescence mode.关键词：Synchrotron radiation;SDD;XAFS;LabVIEW
- 47
- |
- 10
- |
- 0
发布时间：2021-05-24 - 摘要：Background:The avalanche photodiode (APD) has the advantages of small size, high detection efficiency, internal gain and insensitivity to magnet fields. But the internal gain and the signal-noise ratio (SNR) of the output signal of pulse are affected by bias voltage and temperature. Purpose:This study aims to test the effect of bias voltage and temperature on the APD-based front-end readout of scintillation detector. Methods:The avalanche photodiode is employed as the photodetector for CsI(Tl) scintillation, and equiped a charge sensitive preamplifier of low noise to form a probe. The energy resolution of scintillation detector with this probe was tested on a 137Cs radiation source under different bias voltage and temperature. Results:The experimental results show that the energy resolution of the detection system is affected by both the bias voltage and the temperature. When the bias voltage at both ends of the APD is 370 V, the energy resolution is 4.98% for the gamma ray with the energy of 662 keV at the room temperature. Conclusion:The energy resolution will increase with the decrease of temperature within the range of -20℃ to 40℃.关键词：APD;CsI(Tl)scintillation crystal;Bias voltage;Temperature;Energy resolution
- 25
- |
- 11
- |
- 0
发布时间：2021-05-24 - 摘要：Background:Nano-scale structure in solutions can be studied by small angle X-ray scattering (SAXS) techniques at synchrotron radiation facilities. For solution samples, no suitable in-situ variable temperature tank is available to meet the Beijing Synchrotron Radiation Facility (BSRF) 1W2A station's requirements. Purpose:This study aims to develop an in-situ variable temperature tank for solution samples according to the special requirements of SAXS and light parameters of 1W2A station at BSRF. Methods:The liquid samples are heated from both sides to reach a uniform status from 5℃ to 95℃. The solution thicknesses can be adjusted according to their compositions and can maintain a constant during the heating process, which is helpful to increase the data quality. The sample and corresponding background diluent are heated or cooled simultaneously and can be measured alternately. ANSYS was employed to verify the proper structure of the tank. Results:Thermoanalysis results show the rational design of this liquid sample tank, and the temperature was further calibrated for high precision. The structural changes of polyamideamine with temperature were measured using this tank. Conclusion:The proposed variable temperature tank meets the requirements of SAXS in-situ measurements for solution samples at BSRF. All expected functionalities have been satisfied.关键词：SAXS;In-situ variable temperature tank;Temperature correction
- 17
- |
- 9
- |
- 1
发布时间：2021-05-24 - 摘要：Background:Heterogeneous catalysis plays an important role in current energy industry, which demands a deep insight of the catalysis mechanism. In most catalyst related studies, online characterization methods that can yield fast evaluation results and kinetics information under industrial reaction conditions are always desired. Purpose:A novel apparatus for operando catalytic characterization with high flexibility of controlling reaction conditions is introduced. Methods:It performs accurate temperature control from liquid nitrogen region to~500℃ and allows mass spectroscopy (MS) online characterization from atmosphere to high pressure. Results:The apparatus is applied for a temperature programmed desorption (TPD) staring from -150℃ on an Au/TiO2 catalyst CO pre-adsorbed surface. Results show that the setup performs temperature control with good flexibility at low temperature. Conclusion:The apparatus combines features of both wide range temperature controlling and high sensitivity characterization under pressurized conditions, which makes it a powerful tool for understanding catalysis behavior under ambient or high pressure conditions.关键词：Heterogeneous catalysis;Operando analysis;Low temperature control;High pressure reaction
- 25
- |
- 9
- |
- 0
发布时间：2021-05-24
- 摘要：Background Traditional Monte Carlo particle transport calculation codes traverse all the tally cards to find which tallies should be scored at the end of each simulation step. The run time of this procedure almost grows linearly with the number of total tally number. When the tally number is large, the tally procedure costs far more time than the transport calculation. Purpose This paper proposed a tree-based method for scoring massive tallies. Methods The method builds a tally assist tree that all the nodes map one-for-one to the geometry cells. All the tally information read from the input file is stored in the tree. At the end of each simulation step, by mapping the geometry information of the cell where the particle is currently in to a node in the tree, the tallies need to be scored is directly retrieved from the node. Results To test the proposed method, the run time of the Hoogenboom benchmark reactor model with different tally numbers is measured. Conclusion The results show that this method can improve the computation efficiency of massive tally problems.关键词：Monte Carlo;Particle transport;Tally assist tree;Massive tallies
- 31
- |
- 11
- |
- 0
发布时间：2021-05-24 - 摘要：Background Investigations of the distribution and variation of gamma radiation field play an important role in nuclear installation monitor and radioprotection. Purpose In order to obtain the gamma radiation field distribution, one has to deal with the problem of reconstructing the whole gamma radiation field using the small scaled, discrete and irregular distributed experimental data. Methods In present paper, several classic scattered data interpolation techniques are introduced with the emphasis on parallel radial basis function interpolation method, and the Multiquadric algorithm is applied to reconstruct the gamma field. Results For the gamma radiation with rotational symmetry, it is found that, the reconstruction results from Multiquadric method is much better than the result from the built-in interpolation method based on the same sampling data, where the average relative error of Multiquadric result is only 9.47% of the later. For the gamma radiation field with π/2 symmetry, an optimized method for sampling data is proposed and it is found that the average relative error of Multiquadric interpolation results after optimization has been reduced by 64.51% or so. Conclusion Multiquadric method can be applied for the reconstruction of the gamma radiation filed based on small scaled, discrete and irregular distributed detected gamma field information with high precision, and the experimental investigations are also in progress.关键词：Gamma radiation field;Data reconstruction;Visualization;Scattered data interpolation
- 62
- |
- 15
- |
- 0
发布时间：2021-05-24
Nuclear Physics, Interdisciplinary Research
- 摘要：Background One of the functions of the integrated head package is to cool down control rod drive mechanism (CRDM), which is realized through convective flow and heat transfer of cooling gas. Purpose Concerning the integrated head package of ACP100 nuclear reactor, we rigorously compared the thermal-fluid computation results. The emphasis of numerical simulation and comparison was laid on the effect of gas compressibility on heat transfer of cooling gas. Methods The complete mesh model is built by HyperMesh and the thermal-fluid computation results are simulated with commercial ANSYS/CFX software and treating fluid media as both compressible and incompressible gases. Results The simulation results show that the gas compressibility has great impact on the distribution of temperature, velocity and pressure fields. Conclusion Ignoring the compressibility of gas would give an underestimation of maximum temperature on CRDM surfaces, lower maximum velocity and smaller pressure drop on CRDM gaps.关键词：Compressible gas;Integrated head package;Computational fluid dynamic(CFD);Convective heat transfer
- 20
- |
- 10
- |
- 1
发布时间：2021-05-24 - 摘要：Background In-vessel retention (IVR) has become an important severe accident mitigation strategy for advanced light water reactor in recent years. The successful implementation of IVR depends on the external reactor vessel cooling (ERVC) technique. In case of core melt, the bottom head of reactor pressure vessel (RPV) becomes deformed due to the thermal impacts of high temperature, and causes the narrowing of external coolant channel which is the gap between pressure vessel outer wall and insulation layer. This phenomenon could lead to local heat transfer deterioration and then causes the failure of IVR. Purpose The aim of this paper is to analyze the deformation of reactor pressure vessel under IVR condition. Methods The thermal and mechanical calculations of reactor pressure vessel are performed by using the finite element methods. This work can be divided into two steps. The first step is the evaluation of the thermal field of RPV, and the second step is the calculation of stress and displacement of RPV based on its temperature fields. Results The result shows that the maximum vertical deformation of RPV caused by the thermal dilatation is 13.11 mm, while the deformation caused by the other mechanical loads is only about 0.61 mm. After 100-h, the creep leads the vertical deformation increases to 13.85 mm from 13.72 mm. The size reduction of external coolant channel due to the reactor pressure vessel deformation is between 13.85 mm and 18.75 mm. Conclusion With internal pressure of 1 MPa, the deformation of reactor pressure vessel produced by high temperature creep increases as time increases, but the value remains small. The thermal dilatation is the most important factor of the reactor pressure vessel deformation under IVR condition.关键词：IVR;ERVC;Critical heat flux(CHF);External coolant channel
- 20
- |
- 11
- |
- 5
发布时间：2021-05-24 - 摘要：Background Neutral beam injection is one of the main auxiliary heating methods in controllable nuclear fusion experiment. The positive ion source is adopted in the EAST-NBI (Experimental Advanced Superconducting Tokamak-Neutral Beam Injection) device, and during its operation, there is a large energy deposition on ion source components, especially on the electron dump. According to previous research, when beam power is 3.5 MW, the average power density deposited on electron dump is around 4.4 MW·m-2, which may cause great burden for its heat transfer capacity. Purpose Research on the heat transfer conditions of electron dump is of great significance. Methods A numerical simulation method is adopted to calculate the heat transfer effect with the change of beam power and inlet pressure of cooling water, and the maximum operating time of electron dump is obtained. Results The results show that the heat transfer effect decreases with beam power growth, and by enhancing the inlet pressure of cooling water via booster pump, heat transfer capacity gets better to some extent, which can extend the maximum operating time of electron dump. Conclusion This research can guide EAST-NBI ion source to operate safely and steadily. Moreover, it can lay a foundation for increasing heat transfer capacity via structure optimization in future work, which is meaningful for the development of long pulse and high power ion source.关键词：Neutral beam injection;Electron dump;Heat transfer;Maximum operating time;Numerical simulation
- 22
- |
- 12
- |
- 2
发布时间：2021-05-24 - 摘要：Background Thorium-based molten salt reactor nuclear power system project is one of the "Strategic Priority Program" of Chinese Academy of Sciences, and its strategic goal is to develop the fourth generation moltensalt cooled fission reactor nuclear power system. Based on the system design of 10-MWt molten salt reactor-solid fuel, a safety analysis software is developed for the pebble bed reactor system and verified the correctness and accuracy for the high-temperature gas-cooled reactor of results calculated via this software program. Purpose This study aims at accident analyses of uncontrolled rod cluster control assembly bank withdrawal for thorium molten salt reactor-solid fuel (TMSR-SF) by using the developed program. Methods The TMSR-SF reactor core model is built according to the designed parameters. Analyses of the impacts of different shutdown limits and shutdown signals on the withdrawal accident of the TMSR-SF uncontrolled rod cluster control assembly bank is carried out through the safety analysis models such as neutron kinetics model, fluid flow and heat transfer model, control model, etc., in the developed program. Results In the withdrawal accident of the uncontrolled rod cluster control assembly bank of the TMSR-SF, the maximum temperature of the reactor fuel temperature is no more than 860℃. Conclusions Computional results show that the higher the limit value of over power shutdown is, the greater the outlet temperature is; the longer the signal delay time is, the later the reactor shutdown happens, and the higher the core power and fuel temperature is. Compared with the limit value of shutdown, the outlet temperature reaches the limit later in time sequence, the maxumum fuel temperature is much lower than the fuel pebble melting temperature limit of 1 600℃ under no circumstances.关键词：TMSR-SF;Safety analysis;Uncontrolled rod cluster control assembly bank withdrawal;Application development
- 20
- |
- 6
- |
- 5
发布时间：2021-05-24 - 摘要：Background As a new type of reactor, thorium-based molten salt reactor (TMSR) has unique safety and operation characteristics. Its thermal-hydraulic features are enormously different from other reactors, thus worth doing transient analysis. Purpose This study aims at disturbed transient analysis of TMSR for fundamental comprehension of its safety and operation characteristics. Methods The structure and design scheme of the core of 1-GW solid fuel thorium-based molten salt reactor (TMSR-SF) have been presented. Structural emulation platform for transient analysis is proposed with the thermo-hydraulic model being developed on the basis of RELAP5, and the control system model being constructed by using the MATLAB/Simulink software. Results The results of emulation test for operational transient, such as rapid power reduction, step load reducing, linear load reducing and temperature of secondary loop inlet reducing show that the reactor control system is effective to bring the reactor into a safe and steady state without actuation of reactor protection system. Conclusion Analysis results show that the design satisfied the requirements of 1-GW TMSR-SF operational transient. It also indicates that the platform can perfectly simulate the variable power transient conditions.关键词：TMSR;Transient analysis;RELAP5;Simulink;Control rod
- 20
- |
- 10
- |
- 2
发布时间：2021-05-24
Nuclear Energy Science and Engineering
- Address：2019 Jialuo Road, Jiading, Shanghai, China Postal code：201800
- Tel：021-39194977 Email：LHB@sinap.ac.cn
- Technical support is provided by Beijing Founder electronics co., LTD 沪ICP备05005479号-1
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
- Total Visits：675265 Visits Today：341
0