最新刊期
卷 0 ， 期 0 ， 2020
- 摘要：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 CaCO3and 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.关键词：Dust storm;Backward trajectories;X-ray absorption near edge structure(XANES);Particulate matter
- 13
- |
- 12
- |
- 0
发布时间：2021-03-05 - 摘要：Background: In order to open up the application field and improve the source, the Hefei Light Source(HLS) is taken a major upgrade. Purpose: The paper mainly introduces the way of building and measuring of alignment control network during the HLS upgrade. Methods: The global horizontal control network points’ data are measured by total station. All control network points’ 3D-measurement data are obtained by laser tracker and elevation data are got by N3 Level. The function of Unified Spatial Metrology Network(USMN) of SA software is used to make a three dimensional adjustment combining data from different devices. The concept of measurement uncertainty is used to describe the measurement quality of network points. In order to check the correctness of the adjustment result, the software of MAA was employed to make three-dimensional adjustment as well as plane adjustment done by SURVEY adding elevation adjustment by NASEW2003. Results: Through the actual measurement and data processing, the accuracy of actual measurement is 0.09 mm, better than the designed accuracy of 0.15 mm. Compared with the results adjustment by different software, the result of SA is demonstrated to be reliable. Conclusion: The result demonstrates that the designed scheme of alignment control network of HLS upgrade is reasonable and feasible.关键词：Hefei Light Source(HLS);Control network;Laser tracker;Unified Spatial Metrology Network(USMN);Measurement uncertainty
- 19
- |
- 14
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Shields are commonly constructed for a radionuclide neutron source in an actual calibration room in practice. Purpose: Monte Carlo(MC) calculation and experiments were applied to evaluate the effects of scattered neutrons on the neutron radiation field generated by Cf-252 neutron source with a shield. Methods: The effects of scattered neutrons caused by the shield of Cf-252 neutron source were evaluated by calculating the neutron spectra, neutron flux rate and neutron ambient dose equivalent with MC simulation. Similarly, the effects of scattered neutrons caused by the walls, ground and roof of source room were analyzed. Results: The calculation results show that the neutron flux-ambient dose equivalent conversion factor changes from 385 pSv·cm2of a bare Cf-252radionuclide from an idealized situation to 280 pSv·cm2with the shield. The contribution of scattered neutrons from the walls, ground and roof is proportional to the square of distance between wall and source. The experimental data on dose rate are consistent with the calculated results and indicate the reliability of this method. Conclusion: This study provides a practical and feasible way to calibrate the radiation protection instruments using a non-standard radionuclide neutron radiation field.关键词：Neutron radiation field;Shield;Scattering neutron;Monte Carlo method
- 16
- |
- 15
- |
- 0
发布时间：2021-03-05 - 摘要：Background: With the rapid development of radiation technology, demands of functional and structural integration have been put forward for the photon shielding material. Purpose: To meet this need, a new type of carbon fiber reinforced polyimide composite has been designed and tested. Methods: Shielding properties of composite materials of different PbO contents are modeled based on MCNP. According to the simulation results,shielding material is designed and prepared. And its shielding properties, mechanical properties as well as radiation-resistant properties are tested. Results: Through photon shield experiment and mechanical performance experiment, the composite material has good shielding performance for photons. Its photon transmission rate at thickness of 4.80-mm is 54.13% for137Cs(662 keV) gamma-ray, bend strength and stretch strength at 1.2-mm thickness can reach 263 MPa and 369 MPa, respectively. After 90-kGy irradiation, the stretch strength can retain83.47% of its performance. Conclusion: Therefore, the material possesses great application potential in medicine and industry such as gamma ray flaw detection.关键词：Composite;Photon shield;Transmittance;Tensile strength;Bending strength;Modulus
- 14
- |
- 12
- |
- 0
发布时间：2021-03-05 - 摘要：Background:107Pd is an important long-lived fission product of Palladium isotope which is important in cosmology, nuclear technology and environmental studies. The analysis of Pd by Thermal Ionization Mass Spectrometry(TIMS) is difficult because Pd has high ionization potential(8.33 eV). Purpose: The paper attempts to improve mass efficiency of Palladium in TIMS. Methods: Three loading reagents including TaF5, colloidal graphite and phosphate silica-gel are compared. In the three loading reagents, colloidal graphite and phosphate silica-gel are better than TaF5, their mass efficiency can reach 10–7. Using V-type filament, the most of mass efficiency reaches4.55×10–7which is twice as high as that by using single filament. Results: The isotope ratio of 2- g Pd sample was measured with the loading reagent of phosphate silica-gel,106Pd/108Pd deviated 0.36% with standard value, RSD was0.14%(n=10). Conclusion: The experimental results show that the measurement of microgram Palladium sample can obtain good accuracy and precision by using appropriate loading reagents and V-type filament.关键词：Pd;Palladium;Thermal ionization mass spectrometry;Mass efficiency
- 11
- |
- 14
- |
- 0
发布时间：2021-03-05 - 摘要：Background: The development of measuring technologies of radioactive contamination becomes more and more important. Long Range Alpha Detector(LRAD) can effectively solve some problems such as the short ranges of alpha particles, weak penetration ability and so on. LRAD also has advantages that the alpha radioactivity of interior surface of irregular pipes or just irregular surface can be measured nondestructively and precisely. Purpose:This paper attempts to obtain the measured value of multi-point sources and large contamination areas in pipes. And the comparative experiments of impact factors of two different radioactive surface sources(different nuclides and radioactivities) have been done. Methods: In the experiment, a new domestic LRAD is utilized to measure the alpha activity of interior surface of steel pipes. Here, the inner diameter of pipes is 78 mm and there are two kinds of pipes:straight pipe and U-bend pipe. The radioactive sources include241Am(3 772.2 Bq) and239Pu(224.4 Bq). The distance between different sources takes values of 0 cm, 10 cm, 20 cm and 40 cm, respectively, and the distance between the whole mixed radioactive source and detector increases by step of 20 cm. Results: When the relative distance of the two surface sources is 10 cm, the detection efficiency of LRAD is higher than that of relative distance of 0 cm, 20 cm and 40 cm, which matches the result of theoretical analysis. When241Am is closer to the detector than239Pu,measuring results are much higher than those of the opposite situation. And in the same position, when the two sources are put together, the measured results are lower than those of the sum of each single source. Conclusion:Based on the experimental results, a self-developed new LRAD measurement system has been used to measure two non-point sources in pipes.关键词：Long Range Alpha Detector(LRAD);Two-surface source;Detector-source distance;Relative distance
- 12
- |
- 12
- |
- 0
发布时间：2021-03-05 - 摘要：Background: 1-H-1-(3-[18F]fluoro-2-hydroxypropyl)-2-nitroimidazole(18F-FMISO) is a specific molecular imaging probe for tumor hypoxia imaging, and its PET/CT imaging has an important clinical value for planning cancer radiotherapy target volume. Purpose: This study aimed to develop an improved, automated production of18F-FMISO and to perform Micro-PET/CT imaging of tumor hypoxia. Methods: Based on the labeling precursor NITTP and a simple "one-pot" method, an upgraded Explora GN module together with Explora LC was adopted to run radiofluorination(NITTP(10 mg), MeCN(1.0 mL), 120oC,5.0 min), hydrolysis(HCl(1.0 mol/L,1.0 mL), 130oC, 8.0 min) and high performance liquid chromatography(HPLC) purification to produce18F-FMISO automatically. Moreover, Radio-HPLC and Radio-TLC were applied for the quality control, and Micro-PET/CT scanner for hypoxia imaging of SW1990 pancreatic tumor-bearing mice. Results: As results,18F-FMISO was obtained with the synthesis time for about 65 min, the radiochemical yield of(30 5.0)%(no decay corrected, n=20),the radiochemical purity of above 99%, the specific activity of(2.04 0.17)×1011Bq· mol–1, plus with the enhanced chemical purity. Moreover, MicroPET/CT imaging showed that18F-FMISO presented whole-body distribution in SW1990 tumor-bearing mice, and the optimized time point for tumor hypoxia imaging was 3 h post injection with the uptake ratios of tumor-to-muscle of 3.00 0.08. Conclusion: In sum, we developed an improved, automated production of18F-FMISO with high performance liquid chromatography purification, high radiochemical yield, high specific activity and high reliability, and also verified its MicroPET/CT imaging of tumor hypoxia for providing experimental reference data.关键词：18F-FMISO;Tumor hypoxia imaging;Automated synthesis module;High performance liquid chromatography(HPLC) separation;Micro-PET/CT
- 16
- |
- 12
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Developing a style of special imaging device, such as positron emission mammography, is very important for early-stage breast cancer detection and cure. Purpose: The aim is to design planar detectors for positron emission mammography. Methods: The detector was segmented into a pixilated array consisting of 22×74elements. Its crystal pitch and crystal cross section are 2 mm and 1.88 mm×1.88 mm, respectively. The effective area is 44 mm×148.56 mm. The array is coupled to 3 Hamamatsu H8500 position sensitive photomultiplier tubes in neck and neck way. Results: For left detector head, its energy resolution ranged from 10.54% to 19.84% full width of maximum(FWHM), with a mean of 13.34%. For right head, its energy resolution ranged from 11.75% to 33.72%FWHM, with a mean of 14.17%. Coincidence timing resolution for the detector pair is measured to be 2.6 ns FWHM.Effective prompt event rate is 21×103s 1. The image spatial resolutions in X and Y direction are 1.14 mm and 1.20 mm,respectively. Conclusion: The results show that the planar detectors of positron emission mammography are suitable for detecting early-stage breast cancer.关键词：Position emission mammography;Cerium-doped Lutetium Yttrium Orthosilicate;H8500;Symmetric charged division circuit;Detector
- 10
- |
- 11
- |
- 0
发布时间：2021-03-05 - 摘要：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.关键词：Energy dispersive X-ray fluorescence spectrometer;Detector research;Spectra processing;Research status
- 19
- |
- 11
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Real-time, fast, accurate, nondestructive inspection(NDI) and quantitative analysis for chemical warfares are very imperative for chemical defense, anti-terror and nation security. Purpose: Associated Particles Technique(APT)/Neutron Time of Flight(TOF) has been developed for non-invasive inspection of sealed containers with chemical warfare agents. Methods: A prototype equipment for chemical warfare is consisted of an APT neutron generator with a 3×3 matrix of semiconductor detectors of associated alpha-particles, the shielding protection of neutron and gamma-ray, arrayed NaI(Tl)-based detectors of gamma-rays, fully-digital data acquisition electronics, data analysis, decision-making software, support platform and remote control system. Inelastic scattering gamma-ray pulse height spectra of sarin,VX, mustard gas and adamsite induced by 14-MeV neutron are measured.The energies of these gamma rays are used to identify the inelastic scattering elements, and the intensities of the peaks at these energies are used to reveal their concentrations. Results: The characteristic peaks of inelastic scattering gamma-ray pulse height spectra show that the prototype equipment can fast and accurately inspect chemical warfare.Conclusion: The equipment can be used to detect not only chemical warfare agents but also other hazardous materials, such as chemical/toxic/drug materials, if their chemical composition is in any way different from that of the surrounding materials.关键词：Chemical weapon;Associated Particles Technique/Neutron Time of Flight(API-TOF);Non-destructive evaluation;Characteristic gamma-ray
- 12
- |
- 12
- |
- 0
发布时间：2021-03-05 - 摘要：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.关键词：Computational fluid dynamics;Full domain;Pressure loss;Hydraulic load;Bypass flow
- 15
- |
- 12
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Flange is an important component used in the connection between pipes or between pipe and equipment. It is widely used in mechanical industry, petrochemical industry and nuclear industry. Ordinary flange could be oxidized or corroded under high temperature and strong corrosion condition, which leads to flange’s failure.Purpose: The aim is to design and validate the double sealing flange which could be used in high temperature and strong corrosion condition stably and supplied as a reliable detachable connection for petrochemical industry and nuclear industry under high temperature and strong corrosion environment. Methods: New flange is designed using flexible graphite spiral wound gaskets and C style metal ring double sealing structure. The unique protection gas design ensures the graphite spiral wound gasket used in high temperature reliably. Test bed is built to verify the stability of the flange. Results: Pressure reducing of graphite spiral wound gasket is only 0.01 MPa at 750 oC,0.7 MPa for 43 h,there is not obvious oxidation phenomenon at the same time. The leakage rate of metal C sealing ring is 1.51×10–4atm cc/s, and the metal C ring sealing’s performance meets the engineering requirements.Conclusion: The leakage rate of double sealing flange is almost zero under 0.7 MPa at 750 oC, which meets the engineering requirements. It avoids oxidizing at high temperature and corroding under strong corrosion condition.关键词：Flange;Piping connection;Double sealing
- 12
- |
- 16
- |
- 0
发布时间：2021-03-05 - 摘要：Background: Nuclear materials accountancy must be developed for nuclear facilities, which is required by regulatory in China. Currently, there are some unresolved problems for nuclear materials accountancy of bulk nuclear facilities. Purpose: The retention values and measurement errors are analyzed in nuclear materials accountancy of Power Water Reactor(PWR) fuel plant to meet the regulatory requirements. Methods: On the basis of nuclear material accounting and evaluation data of PWR fuel plant, a deep analysis research including ratio among random error variance, long-term systematic error variance, short-term systematic error variance and total error involving Material Unaccounted For(MUF) evaluation is developed by the retention value measure in equipment and pipeline. Results: In the equipment pipeline, the holdup estimation error and its total proportion are not more than 5%and 1.5%, respectively. And the holdup estimation can be reagarded as a constant in the PWR nuclear material accountancy. Random error variance, long-term systematic error variance, short-term systematic error variance of overall measurement, and analytical and sampling methods are also obtained. A valuable reference is provided for nuclear material accountancy. Conclusion: In nuclear material accountancy, the retention value can be considered as a constant. The long-term systematic error is a main factor in all errors, especially in overall measurement error and sampling error. The long-term systematic errors of overall measurement and sampling are considered important in the PWR nuclear material accountancy. The proposals and measures are applied to the nuclear materials accountancy of PWR fuel plant, and the capacity of nuclear materials accountancy is improved.关键词：Nuclear material accounting;Material Unaccounted For(MUF);Key measurement point;Balance area;Retention value
- 15
- |
- 12
- |
- 0
发布时间：2021-03-05
- 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