最新刊期
卷 38 ， 期 3 ， 2015
- 摘要：Background: Graphene Oxide (GO) is a type of two-dimension carbon nanomaterial with promising environmental application due to its good solubility in water, high absorbability and catalytic activity. Humic Acid (HA) is the main component of Natural Organic Matter (NOM) in water, which could be adsorbed on the surface of GO nanosheets via π-π interaction and then affect the physicochemical properties of GO in aqueous system. Purpose: Investigating the interaction between GO and HA will provide some insights for environmental application of GO. Methods: We employed Synchrotron Radiation Circular Dichroism spectroscopy (SRCD), Ultraviolet-Visible spectroscopy (UV-Vis) and Fourier Transform Infrared spectroscopy (FTIR) to explore the interaction between GO and HA under different mass ratio of HA to GO, environmental pH and temperature. Results & Conclusion: UV-Vis spectroscopy of GO-HA showed that the intensity of the absorption peak at 228 nm gradually increased when the mass ratio of HA to GO increased to 4:1 from 1:4 and the FTIR C-O stretching vibration shifted and decreased, indicating the strong π-π interaction and hydrogen bonding between GO and HA. GO showed a broad peak at about 240 nm in SRCD spectra which origin from its surface O-containing functional groups, folding or curl of the nanosheets. SRCD indicated the interaction between GO and HA could change the dispersion behavior of GO and then affect CD activity of GO-HA, depending on the mass ratio of HA to GO, environmental pH and temperature. GO-HA showed higher CD activity with the increased pH and decreased temperature (4 °C) due to the increase of folding state. Abstract关键词：Graphene Oxide (GO);Humic Acid (HA);Interaction;Synchrotron Radiation Circular Dichroism spectroscopy (SRCD)
- 22
- |
- 10
- |
- 1
发布时间：2021-03-03 - 摘要：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). Abstract关键词：In-phase/Quadrature (I/Q) demodulation;Amplitude imbalance;Phase imbalance;Calibration
- 19
- |
- 11
- |
- 3
发布时间：2021-03-03 - 摘要：Background and Purpose: EPU200 (Elliptically Polarized Undulator) is designed to produce radiation with low on-axis power density in Shanghai Synchrotron Radiation Facility (SSRF) for experiment requirements of users. Methods: EPU200 is the first novel permanent magnet undulator which has eight rows of magnetic blocks and can produce different kinds of polarized radiation with low on-axis power density. The magnetic structure is installed on four aluminum beams, so there are two magnetic blocks which are installed in one magnet keeper. The arrangement of the magnetic blocks is complex, so there are various magnetic forces on the magnets. And the space between the magnetic blocks is small. Results: The mechanical structure and installation of the magnetic structure are accomplished, and the calculation results of magnetic force by Radia program are obtained. Conclusion: The results show that the magnetic structure of EPU200 by ANSYS Workbench ensures the feasibility of this structure.Cited关键词：Novel undulator;Magnetic structure;Mechanical design;Finite element analysis
- 22
- |
- 14
- |
- 0
发布时间：2021-03-03 - 摘要：Background: Monte Carlo method is regarded as the most accurate method for dose rate calculation at present, whereas its time-consuming defect increases complication for its application in industrial irradiation processing and experiment. Purpose: For a single-rack cobalt irradiation facility with loaded activity of 8.4PBq, a study of optimizing MCNP (Monte Carlo N Particle Transport Code) parameters was done to improve computational efficiency of dose rate. Methods: The effects of five parameters on MCNP computational efficiency, including the thread numbers of parallel computation, tally method, cell size, cutoff energy, and methods dealing with γ-induced electrons were discussed. Results: With certain precision and relative error, the least time-consuming situation was achieved with a set of five parameters, including parallel computation with hyper-thread mode, *F6 tally, cell size of 1cm, γ transport mode and γ-cutoff energy of 100keV. Conclusion: In this work, the cost of time was reduced about 57 times, and the improvement of MCNP computational efficiency was realized.Cited关键词：Single-rack cobalt irradiation facility;Absorbed dose rate;MCNP (Monte Carlo N Particle Transport Code);Computational efficiency
- 20
- |
- 12
- |
- 0
发布时间：2021-03-03 - 摘要：Background: Due to the integration of the advantages of the inorganic filler phase and the polymer phase, the organic-inorganic hybrid membrane, which can overcome the trade-off effect between permeability and selectivity, is widely used in many areas. Purpose: The aim is to study the microstructure of the PDMS-MIL-101(Cr) (Poly (dimethyl siloxane)-Material Institute Lavoisier-101(Cr)), which is a polymer-metal organic framework (MOFs) materials hybrid membrane. Methods: Positron annihilation lifetime spectroscopy (PALS) and coincidence Doppler broadening energy spectroscopy (CDBES) were used. Results: PALS results showed that the size of both the space at cross linking site and the free volume of polymer matrix decreased when the MIL-101(Cr) keep increasing, which indicates that MOFs penetrated into the free volume of polymer. Moreover, according to the CDB ratio spectra of hybrid membranes to single silicon crystal, it can be found that the effect of positron preferential annihilation with oxygen atoms was weakened with much more MIL-101(Cr) in hybrid membranes, and a fraction of positrons annihilated with the electrons of metal atoms locating at the center of subnanometer particles of MIL-101(Cr). It is inferred that after entering the free volume of polymer, MIL-101(Cr) particles may interact with oxygen atoms, thus partly block the way for positron’s access to oxygen atoms. Conclusion: Positron annihilation technique is proved to be effective to characterize the microstructure of organic-inorganic hybrid membranes. Abstract关键词：Positron annihilation;Free volume;Hybrid membrane;PDMS-MIL-101 (Poly (dimethyl siloxane)-Material Institute Lavoisier-101)
- 31
- |
- 13
- |
- 2
发布时间：2021-03-03 - 摘要：Background: In the process of nuclear related production or processing, nuclear fuel and other radioactive substances will produce radioactive aerosols which is harmful to the environment and human health. The commercial available monitor of radioactive material is either poor in continuity or limited in measuring radioactive aerosols. Purpose: This study aims to design a radioactive aerosol monitor for continuous concentration surveillance of radioactive aerosol in real time. Method: This instrument’s stability and efficiency has been improved with the IPC+ARM architecture and the SQLite database which can store massive amounts of nuclear data and other information. After operating the spectral data which gathered by multi-channel pulse height analysis with α/β ratio method, we embedded some algorithms that recommended on ISO 11929-5 to calculate the concentration. Results: We have achieved a high precision and the instrument has been run steadily for a long time. Conclusion: This paper described the design for continuous monitoring of radioactive aerosol, and enhances the stability and efficiency of the system in hardware and software. Finally, in the processing of spectral data collected by multi-channel pulse amplitude analyzer, we have achieved a high precision with ISO11929-5 algorithms and verified the feasibility of the system. Abstract关键词：Radioactive aerosol;Continuous monitoring device;IPC+ARM;SQLite;ISO 11929-5
- 22
- |
- 13
- |
- 0
发布时间：2021-03-03 - 摘要：Background: The Main Cooler Storage Ring at Heavy Ion Research Facility in Lanzhou (HIRFL-CSRm) has 30 power supplies for the quadrupole magnets, with a big volume of 1 000 mm×1 000 mm×2 000 mm. Purpose: We attempt to significantly reduce the size of the equipment and improve the integration of the components and power density of the power supply. Methods: Firstly, a suitable and original topology is selected for overall design. Through changing the construction of the parts of the rectifier filter, power converter, high-frequency filter and the controller, digitalization, modularization and standardization were applied to reduce the costs and the geometric dimension. Thermal simulation of the power unit was performed before the prototype is completed, and the Electro Magnetic Compatibility (EMC) was tested finally. Results: The size of new designed power supply was decreased to 600 mm×800 mm×1800 mm, and the performance testing results satisfied all of the design requirements. Conclusion: The modularized design of high power pulsed power supply not only reduce the geometric volume, increasing its power density, but also improve its overall performance, proving a feasible and meaningful reference for high power density equipment. Abstract关键词：High power density;Pulsed power supply;Modularization;Thermal simulation;Electro Magnetic Compatibility (EMC)
- 18
- |
- 13
- |
- 0
发布时间：2021-03-03 - 摘要：Background: Multi-purpose Reflectometer (MR) is one of the three spectrometers under construction at China Spallation Neutron Source (CSNS). The reflection arm is a key component in MR, which is used to carry the neutron detector. The size of the reflection arm is 1750 mm×1000 mm×800mm (L×W×H), and the weight is 1200kg. The reflection arm should rotate around the sample center with a rotation range of 130°, and the accuracy of the rotation should be higher than 0.001°. Purpose: This study aims to design the structure with the combination of air bearing support and friction wheel drive for the movement request of heavy load, large travel and high precision in the reflection arm. Methods: A high precision rotation stage with air bearing support is developed to verify the feasibility of this structure in which no contact and friction between reflection arm and granite floor when the air bearing works. The air floating stage is supported by three sets of air bearings, which is placed on a granite platform with the size of 1000mm×2000mm, a sample stage base is located on one side of the granite platform, a sheet steel is used to connect the air floating stage and the cross roller bearing which is installed in the sample stage base, a friction wheel is installed in the side of the air floating stage. The rotation range of the air floating stage is 45°, and the load of the air floating stage under test is 800kg. Results: The accuracy test indicates that the rotation stage with air bearing support can offer the repeatability positioning accuracy of 0.00031°, and the positioning accuracy of 0.0009° within the scope of whole rotation range. Conclusion: These results show that the structure with the combination of air bearing support and friction wheel drive can satisfy the movement requirement of the reflection arm in MR. Abstract关键词：Air bearing support;Friction wheel drive;Accuracy test
- 18
- |
- 9
- |
- 1
发布时间：2021-03-03 - 摘要：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. Abstract关键词：Chinese Spallation Neutron Source (CSNS);General Purpose Powder Diffractometer (GPPD);Real-time signal;Jitter;Aurora protocol;Optical
- 16
- |
- 10
- |
- 0
发布时间：2021-03-03 - 摘要：Background: In deep penetration application such as well-logging, medical physics and radiation shielding, analog Monte Carlo method will cause long calculation time and large variance. The newly released Monte Carlo code MCNP5 version 1.51 allows almost all of MCNP’s variance reduction techniques to be used with pulse height tally. Purpose: This paper aims to find an optimize pulse height variance reduction technique (PHVRT) to solve low efficiency with pulse-height tallies in deep penetration problems. Methods: A variety of variance reduction techniques including an auto-important sampling method-Mesh-based weight windows were proposed, and all kinds of variance reduction techniques proposed were tested and results with different variance reduction techniques were compared. Results: Mesh-based weight windows used with DXTRAN and forced collision get good calculation efficiency. After optimizing, the efficiency can be improved with large amplitude. Conclusion: Mesh-based weight window used with other variance reduction techniques can resolve deep penetration problem effectively. Abstract关键词：Deep penetration;Pulse height tally;Variance reduction;Mesh-based weight windows
- 29
- |
- 9
- |
- 5
发布时间：2021-03-03 - 摘要：Background: To assess the capability of radionuclide laboratories, the proficiency test exercises (PTEs) of filter samples have been carried out by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) once a year since 2000. Purpose: This article presents the experience that Beijing radionuclide laboratory participated in PTE2012. Methods: A total of twenty four nuclides were added in the reference sample, of which eleven are considered “major” and thirteen are considered “minor”. The sample was measured by an HPGe detector with 76% relative detection efficiency. Results and Conclusion: Eleven major and twelve minor nuclides were identified in the reference sample. The measurement activities of major nuclides are accurate and the zero time that determined by the 95Nb/95Zr activity ratio is in agreement with the reference value, and the deviation is only 0.03 d. Abstract关键词：Comprehensive Nuclear-Test-Ban Treaty (CTBT);Filter sample;Proficiency test exercise (PTE);Activity;Zero time
- 14
- |
- 10
- |
- 1
发布时间：2021-03-03 - 摘要：Background: In the non-destructive measurement, including the analysis of material composition of nuclear forensics, fission product analysis of nuclear terrorism event and large sample activation analysis, there is a big challenge for the detection efficiency calibration. Purpose: This paper analyzed the basic principle of the relative efficiency method of radiation samples with multi-nuclide, and established the relative efficiency fitting method for multi-nuclide. Methods: Through the peak information of the fission products from a special irradiated uranium sample, the efficiency fitting of dual-nuclide (parent-daughter nuclides) and three nuclides (no parent-daughter nuclides) was verified. Results: The study showed that the calibration factor of the self-calibration method with multi-nuclide was consistent with the factor of the parent-daughter nuclides’ decay in the error range of 2%. Conclusion: Results laid the foundation for the non-destructive analysis techniques of the radioactive samples with special shapes. Abstract关键词：Relative efficiency;Multi-nuclide;Least square method
- 15
- |
- 11
- |
- 0
发布时间：2021-03-03 - 摘要：Background: High-temperature molten salt has a wide range of applications, which has been considered as an extremely potential medium for heat transfer and storage in concentrating solar thermal power plants and molten salt reactors. Purpose: The aim is to obtain the heat transfer characteristics of molten salt during fluoride volatility processing of spent fuel reprocessing in molten salt reactor. Methods: Based on the convective heat transfer experimental apparatus of ternary nitrate salt and oil, the heat transfer characteristics of molten salt in the laminar flow region was studied. Calculation correlation for Nusselt number (Nu) was evaluated against the experimental data. Results: Based on the Sieder-Tate correlation, a new correlation was proposed by fitting experimental data. The new correlation was evaluated by using Fluent6.3 software. Conclusion: The new correlation can accurately predict the heat transfer characteristics of molten salt in laminar flow region by comparison with the temperature distribution in the heat exchanger. Abstract关键词：Molten salt;Laminar flow region;Heat transfer
- 24
- |
- 11
- |
- 4
发布时间：2021-03-03 - 摘要：Background: Tritium, as a by-product in the core of Thorium-based Molten Salt Reactors (TMSRs), easily diffuses through the structure materials at high temperatures and into the atmosphere. Purpose: To reduce the damage of tritium to the environment, it is necessary to research the permeation behaviors of tritium in the candidate structural materials of TMSRs. Methods: In this study, Hastelloy alloy C230, Hastelloy alloy C276, Hastelloy alloy N and GH3535, the candidate structural materials of TMSRs, were used. With the method of gas driven permeation, hydrogen and deuterium were used to simulate the permeation process of tritium and their permeabilities in these materials were examined at the temperature range of 400?700 oC. Results: The fluxes of hydrogen and deuterium were proportional to the square root of the gas pressure. Their permeabilities were a little different in these alloys and increased with experimental temperature. The relationship between the permeability and the reciprocal of the temperature was suit for Arrhenius formula. Conclusion: The permeabilities of hydrogen isotopes in GH3535 and Hastelloy alloy N are very close, which is in the same magnitude with that in Hastelloy alloy C230 and Hastelloy alloy C276. At the experimental temperatures, the ratios of the permeability between hydrogen and deuterium in these materials are all close to 1.4, which is consistent with the classical diffusion theory. According to the theory, pre-exponential factors for tritium permeation in these materials are 1.1×10?7?1.6×10?7 mol?m?1?s?1?Pa?1/2 and activation energy is 59?62 kJ?mol?1.Cited关键词：Hydrogen isotope;Molten Salt Reactor (MSR);Structural material;Permeability
- 31
- |
- 9
- |
- 2
发布时间：2021-03-03 - 摘要：Background: As one of the six candidates recommended by the fourth generation reactor forum, Molten Salt Reactor (MSR) owns many features such as high outlet temperature, high energy density, and anhydrous cooling. In the core of the first Thorium Molten Salt Reactor with Solid Fuel (TMSR-SF1), most of the structure materials are graphite. 13C in graphite and the impurities N and O in coolant can be activated to produce 14C. 14C has long half-life, it can be involved in various complex biological cycle with other stable nuclides 12C and 13C. In TMSR-SF1, 14C is widely distributed in the coolant, the active core and the structure materials. Purpose: The aim is to study the production and release of 14C in TMSR-SF1. Methods: According to the design parameters of TMSR-SF1, TRITON (Transport Rigor Implemented with Time-dependent Operation for Neutronic depletion) of SCALE6.1 (Standardized Computer Analyses for Licensing Evaluation) was applied for the transport burnup coupled calculation. Results: Computational results show that the radioactivity of 14C in main loop mainly comes from the activation of N, and the total amount of radioactivity of 14C in the main loop is 0.34 TBq each year. Conclusion: TMSR-SF1 could meet the current emissions standards of 14C according to current design parameters. Abstract关键词：Thorium Molten Salt Reactor with Solid Fuel (TMSR-SF1);14C;Production;Release
- 25
- |
- 12
- |
- 0
发布时间：2021-03-03 - 摘要：Background: The study of natural circulation of Lead Bismuth Eutectic (LBE) has great significance for the Accelerator Driven Sub-critical systems (ADS). Purpose: This study aims to analyze the factors and the interaction between different factors on natural circulation flow of LBE. Methods: Based on the previous experimental results obtained by ADS team, the factorial analysis method is applied to study the steady flow of lead bismuth eutectic under natural circulation using typical data. Results: The pipe diameter size accounts for about 65.94% of the total influence on the steady state flow whilst the temperature difference accounts for 16.89%, the temperature difference and tube diameter interaction accounts for 7.44%, the height difference and tube diameter account for 2.7%. Conclusion: The pipe diameter size is the most important influence factor of the steady flow of lead bismuth eutectic, much larger than all others such as temperature difference, interaction between temperature difference, tube diameter, and the interaction between height difference and tube diameter. Abstract关键词：Lead Bismuth Eutectic (LBE);Natural circulation;Factorial analysis
- 20
- |
- 11
- |
- 0
发布时间：2021-03-03 - 摘要：Background: The neutron absorbing materials used for spent fuel storage grids in the nuclear power plant need to meet the structural and functional integration requirements. Purpose: This paper has proposed the high content B4C/Al neutron absorbing materials reinforced by carbon fiber. Methods: Monte Carlo method has been used to calculate the neutron transmittances of carbon-fiber reinforcing B4C/Al neutron absorbing materials (Cf/B4C/Al). Result: The effects of some factors on the neutron transmittances of Cf/B4C/Al composite have been studied such as B4C and Cf contents, incident neutron energy and material thickness, which also have been compared with those of B4C/Al materials. Conclusions: The results show that for 1 eV?0.1 MeV incident neutron, when the content of B4C is less than 35%, the addition of carbon fibers can significantly improve the neutron shielding performance of B4C/Al composite. For 100-eV incident neutron, the transmittance of the material decreases exponentially with the increase of B4C content. The neutron transmission of Cf/B4C/Al decreases with the increase of carbon fiber content up to 10%. The optimal component ratios of Cf/B4C/Al were designed as 35% B4C and 10% Cf. In order to shield the neutron radiation as effectively as a 0.5-mm-thick cadmium plate, the thickness of Cf/B4C/Al was also designed as 9.42 mm. The study will provide the theoretical guidance for the design and application of the neutron absorbing materials. Abstract关键词：Cf/Al/B4C;MCNP;Neutron transmittance;Components design
- 18
- |
- 12
- |
- 0
发布时间：2021-03-03
- 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：675330 Visits Today：406
0