最新刊期
卷 0 ， 期 0 ， 2020
- 摘要：Background: Time synchronization is one of the core technology of realizing the real-time control of accelerator under the distributed control system architecture. The ordinary crystal frequency deviation of IEEE1588 causes low synchronous accuracy, which doesn’t meet the needs of high precision synchronization. Purpose: This paper proposes an algorithm to improve the synchronization precision caused by the crystal frequency deviation. Methods: According to the basic principle of IEEE1588 time synchronization, a dynamic frequency compensation (DFC) algorithm module was designed and a test platform was built to verify the feasibility and practicability of the algorithm. The influence of the synchronous cycle and delay jitter of the switch on the synchronization accuracy were analyzed. Results: Experimental results showed the great precision improvement of synchronization after using DFC algorithm. Conclusion: Low synchronous accuracy caused by the crystal frequency deviation can be improved by using DFC algorithm implemented for precision time protocol (PTP) of IEEE 1588.Cited关键词：IEEE1588;Dynamic frequency compensation;Synchronous cycle;Delay jitter
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发布时间：2021-03-03 - 摘要：Background: The determination method of 235U fission number by detecting fission products using HPGe detector has been established before. But in some special cases, we need to get the fission number in-time in high intensity radiation environment. HPGe detector has its limitation due to the complex g spectrum accompany with high flux. Purpose: To get rid of the limitation mentioned above, a new method is introduced by detecting the delayed g-rays absorbed dose rates. Methods: By using independent fission yield together with radioactive decay dates from CENDL 3.0 and ENDF BVII.1, dynamic calculation for total absorbed dose rate in air 1 meter from the source whose compositions were thermal neutron-induced fission products of 235U has been done. Results: A set of absorbed dose rate data of 235U fission products irradiated through fast rabbit irradiation system on Xi’an pulse reactor was recorded. The deviation of the fission neutron number between method by g-rays absorbed dose rates and method by HPGe detector is 7%. Conclusion: It’s feasible to determine the fission neutron number of 235U using delayed g-rays absorbed dose rates in a high intensity radiated environment.Cited关键词：Fission neutron number;Absorbed dose rate;Fission products
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发布时间：2021-03-03 - 摘要：Background：The In situ leaching (ISL) of uranium mining is an important method to nuclear reactors for sustainable utilization of nuclear energy. Surfactants have their potential role in the increasing permeability of ore bed and the leaching rate of uranium in ISL. Purpose: The aim is to study the application of surfactants in ISL and identify whether the addition of surfactants have any effect on the resin property. Method: The influence of several surfactants such as OP-10, FSO, LVA, LF221 and their complexes on resin adsorption and elution of uranium from production solutions for ISL were researched by column experiments. Results: The results show that adding 50−100mg•L−1 different surfactants and their complexes into the production solutions for ISL has no significant influence on the resin adsorption and elution of uranium, in which the adsorption curve, sorption capacity of resin and recycling of resin are the same with the experimental results without surfactants. The adding of surfactants can increase the peak concentration of uranium in eluents and reduce the residual uranium content in resin, which promotes the elution efficiency. It also showed that the complexes of OP-10 and FSO are the best among various surfactants. Conclusion: As mentioned above, the surfactants can be used in ISL of uranium mining very well.Cited关键词：Resin adsorption;Elution;Surfactant;In situ leaching of uranium mining
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发布时间：2021-03-03 - 摘要：Background: Plasma stealth is one of the most important branches of the electromagnetic stealth technology. ?-ray could ionize the air and excite the plasma. Under certain conditions, the plasma has stealth effect to the radar wave. Purpose: The aim is mainly to investigate the plasma stealth excited by 90Sr/90Y. Methods: We calculated the density distribution of the plasma excited by 90Sr/90Y with different radioactivity through configuring the weighting factor based on the decay energy spectrum of 90Sr/90Y with the electron diffusion and recombination in the air taken into consideration, and obtained the reflectivity of the plasma that was excited by infinite metal plate coated with 90Sr/90Y to electromagnetic waves with different incident angles and frequencies using the WKB (Wentzel-Kramers-Brillouin) method. Results: The reflectivity of the plasma with the radioactivity being 3.7×1010Bq?cm?2 and 3.7×1011Bq?cm?2 to the vertically incident electromagnetic wave of 1.5 GHz could reach ?2.2dB and ?7.45dB respectively. Conclusion: In the range of 1–100GHz, the reflectivity increases monotonically with the frequency, while decreases monotonically with the increase of incident angle. The stealth effect of the plasma excited by 90Sr/90Y with a certain radioactivity is of significance.Cited关键词：Plasma;Electron density;Reflectivity;Stealth technology;Radioactively exciting
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发布时间：2021-03-03 - 摘要：Background: Determination of the uranium isotope abundance ratio of fuel pins is a significant stage for the quality control in safe operations of reactor. Purpose: The aim is to establish a method to examine the 235U abundance of fuel rod with fast neutron as an excitation source. Methods: Taking the fission-yield ratios of / and / as the subjects of research, the relation curves between the average yield ratios and the 235U isotopic abundance as well as the expressions , in which the average yield ratio ( ) is a function of the 235U isotopic abundance (H0), were obtained and presented based on the previous studies. Results: In order to testify the accuracy of the method, the simulation sample of 72.2% is measured by working curve, and RSD is less than 2%. Within the limit of error, the results of sample analysis are in correspondence with those of passive gamma ray method. Conclusion: All of these results indicate that the method is feasible to determine the 235U abundance of fuel rod.Cited关键词：Fission yield;Uranium isotope;Abundance;Difference method
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发布时间：2021-03-03 - 摘要：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.Cited关键词：Radiography;Proton;Translation process;Monte-Carlo simulation
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发布时间：2021-03-03 - 摘要：Background: The interaction between continental and oceanic process is much intense in coastal region. The terrestrial freshwater mixes with seawater here which leads to the chemical constituents in water undergo rapid change. Purpose: The aim is to analyze and study the distribution characteristics of 224Ra and 226Ra and their influence factors in the water of Jiaozhou Bay area. Methods: The water samples of 224Ra and 226Ra were collected from groundwater, river water and seawater around the Jiaozhou Bay from April to May, 2012. In the laboratory, the activities of 224Ra absorbed on the Mn-fiber were measured through the continuous emanation method. Finally, the Mn-fiber was sealed for more than 7 days, and the activities of 226Ra absorbed on the Mn-fiber were measured through the direct emanation method. Results: The results show that the activities of 224Ra and 226Ra in groundwater and river water are much higher in the granitic area which has higher concentration of 232Th and 238U. Because of mixing with seawater, the salinity of groundwater and river water in coastal region rises which leads to the increasing amounts of 224Ra and 226Ra desorbed from the particles, resulting in higher activities of 224Ra and 226Ra in coastal region. Affected by the input of river (dissolved and desorbed from suspended particles) and submarine groundwater discharge (SGD), the activities of 224Ra and 226Ra are relatively higher in nearshore seawater, then with the decay of 224Ra and mixing dilution effect of the offshore seawater, the activities of 224Ra gradually decrease from nearshore region to the open ocean. The activities of 226Ra in the seawater of Jiaozhou Bay remain high-level values, and there are only a few zones of low 226Ra activities. The main reasons are that the activities of 226Ra from terrestrial freshwater are close to those from offshore seawater and the half-life of 226Ra is very long. Conclusion: The activities of 224Ra and 226Ra in groundwater relate to the rock around Jiaozhou Bay and the water salinity. In addition to rock and water salinity, the activities of 224Ra and 226Ra in river water are also concerned with human activities and the process of groundwater recharge. The activities of 224Ra and 226Ra in seawater depend on the sources and sinks of radium isotopes.Cited关键词：Groundwater;River water;Seawater;224Ra;226Ra
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发布时间：2021-03-03 - 摘要：Background: The noninvasive imaging of cell death plays an important role in the evaluation of degenerative diseases and detection of tumor treatments. Duramycin, a peptide with 19-amino acid, is produced by Streptoverticillium cinnamoneus. It binds specifically to phosphatidylethanolamine (PE), a novel molecular target for cell death. Purpose: The aim is to develop a synthetic method to label duramycin using 18F ion. The automated synthesis was carried out by multi-step procedure on the modified PET-MF-2V-IT-I synthesizer. Methods: Firstly, the prosthetic group of 4-nitrophenyl 2-[18F]fluoropropionate (18F-NFP) was automatically synthesized by a convenient three-step procedure. Secondly, 18F-FPDuramycin was synthesized by conjunction of 18F-NFP with duramycin, which was purified by a solid-phase extraction cartridge. Orthogonal test was performed to confirm the suitable reaction conditions (solvent, base and temperature). Results: The radiochemical yields of 18F-NFP were (25±5)% (n=10, decay-uncorrected) based on [18F]fluoride in 80 min. 18F-FPDuramycin was obtained with yield of (70±3)% (n=8, decay-uncorrected) based on 18F-NFP within 20 min. The radiochemical purity of 18F-FPDuramycin was greater than 99% and the specific activity was greater than (23.7±13.7) GBq??mol?1 (n=10). Conclusion: 18F-FPDuramycin injection is easy to be prepared with “two-pot reaction” and is a promising radiotracer used for the clinical and scientific study on positron emission tomography (PET) imaging.Cited关键词：Automated synthesis;18F-FPDuramycin;Cell death;Phosphatidylethanolamine;Radiolabeling
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发布时间：2021-03-03 - 摘要：Background: Nuclear track membranes offer distinct advantages over conventional membranes due to their precisely determined structure. Their pore size, shape and density can be controlled intentionally so that a membrane with the required characteristics can be produced. The track etching technology plays an important role in the production of nuclear track membranes. Purpose: The effect of potassium permanganate solution pretreatment on the etching rate for polyethylene terephthalate film (PET) is studied in this work. Methods: The conductivity method is used in this research. Under different conditions, the PET films were pretreated for 1 h, 2 h, 3 h, 4 h, 5 h and 6 h by potassium permanganate solution. 5%, 15%, 25%, 35% of 2-mol?L?1 sulfuric acid solutions were added in 0.1mol?L?1 potassium permanganate solution. Results: Track etching rate reached a peak at 2 h, Afterwards, with the pretreatment time increasing, the track etching rate declined, and the longer of the pretreatment time, the smaller of the bulk etching rate. Half cone angle either. Adding to sulfuric solution, the experimental results show that the effect on track etching rate is small, with the amount of sulfuric acid increasing, bulk etching rate becomes larger, the same change with half cone angle. In addition, the DC voltage used in the conductivity method also has impact on the track etching rate. Conclusion: The experiment has provided a method to improve the etching rate.Cited关键词：Potassium permanganate solution;Track etching rate;Bulk etching rate;Half cone angle
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发布时间：2021-03-03 - 摘要：Background: Liquid fluoride-salt-cooled high temperature reactor, one of the GEN-IV reactors, has great advantages comparatively, and the research on its fuel is of great significance. Purpose: The aim is to study the physical properties of high-temperature pebble-bed reactors loaded with six different fuel mixtures. Methods: We used SCALE5.1 package to compute some important parameters like excess reactivity, full power operation days, burnup and neutron spectrum. Results: The results show that the true conversions of 232Th are much less than those of 238U when mixed with 233U or 235U. With 239Pu for starting, 232Th contributes to making the reactor running longer than that with 238U. Conclusion: With respect to saving fuel and extending the life of the core, without online refueling and reprocessing, 232Th is underperformed in thermal reactor compared with 238U, however, it is the opposite in epithermal neutron reactor.Cited关键词：High-temperature reactor;Pebble-bed reactor;Pebble;TMSR (Thorium Molten-Salt Reactor);Epithermal neutron reactors
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发布时间：2021-03-03 - 摘要：Background: Thorium-Uranium cycle plays an important role in the future’s power production technology. Nuclear data involved are urgently needed for engineering design and other purposes since there are obvious differences between the existing evaluated data. Macroscopic neutron integral experiment can be used as a good tool to survey the confusion. Purpose: Macroscopic neutron integral experiment based on radioactive method was carried out to measure the generation ratio of 233U nuclide and the average radiation capture cross section of 232Th while a ThO2 sample was irradiated by fast neutrons leakage from a fast critical facility. We expect that these data can be used as a reference for the research of Th-U cycle. Methods: Radiation capture reactions of 232Th nuclides occur when the nuclides are irradiated by neutrons. 233U nuclides will be generated after two cascade decays by emitting beta rays from the activation products, which are 233Th nuclides. The ThO2 sample was prepared as a slice of 20mm×10 mm from 0.74336-g ThO2 powders of 99.9% enriched. The neutron flux was measured by activation method which was 4.07×109 cm?2?s?1 at the sample’s irradiation position while the facility worked at the power level of 180 watts. The leakage neutrons’ energy distribution was calculated by MC method and it is very close to the fission spectrum with the averaged energy of 1.42 MeV. After irradiation and then a period of cooling time the gamma rays emitted from the sample were measured by an HPGe spectrometer which had been pre-calibrated. From these data the activity of 233Pa was calculated and then the generation ratio of 233U and the average radiation capture cross section of 232Th were calculated. The measured average radiation capture cross section was compared with the cross sections calculated based on the ENDFB-VII.1, CENDL-3.1, JENDL-4.0, BROND2.2 databases. Results: The measured generation ratio of 233U was 4.01×10?12 with an uncertainty of 6.1% while the neutron fluence at the irradiation place was 2.99×1013 cm?2 and the measured average radiation capture cross section of 232Th was 134.3 mb with an uncertainty of 12.4%. The average radiation capture cross section calculated based on CENDL-3.1 database was 18.5% smaller than the measured one. Conclusion: More experimental data are needed to evaluate the serviceability of the cross sections of 232Th (n,γ) reaction from different databases.Cited关键词：Th-U cycle;Nuclear fuel analysis;Critical facility;Activity;Average cross section
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发布时间：2021-03-03 - 摘要：Background: The Molten Salt Reactor (MSR) is one of the six advanced reactor types for future nuclear energy systems in the Generation IV International Forum (GIF), possessing the advantages of good neutron economics, inherent safety, processing online, nuclear nonproliferation, etc. Due to the fluid fuel, a part of delayed neutron precursors drifts out of the reactor and decays in the loop, which is different from the solid-fuel reactor. Purpose: The distribution of delayed neutrons with different fuel velocity for Molten Salt Reactor Experiment (MSRE) is analyzed to provide reference for safety design of MSR. Methods: Based on the neutron kinetics and approximate method of homogeneous reactor, a distribution model of delayed neutron was presented. This model is applied to the distribution study of delayed neutrons with different fuel velocity. Results: The number of delayed neutrons in a core radius of 20 cm was more than that in a core radius of 30 cm. When the flow velocity of fuel decreased by a half, the discrepancy of delayed neutrons between the fifth-group and sixth-group precursors is within 6%. Conclusion: The number of delayed neutrons is increasing toward the center of reactor core. The group of delayed neutron precursors with shorter half-time has little effect on the flow velocity of molten salt.Cited
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发布时间：2021-03-03 - 摘要：Background: In the second generation pressurized water reactor, the Control Rod Drive Mechanism (CRDM) is mainly cooled by the blast blower, which consumes more energy and is of lower security. Based on the layout of the CRDM group in the Daya Bay nuclear power plant, the EMC-B type of CRDM is taken as research object. Purpose: The temperature distribution of the CRDM group was simulated to verify the feasiblity of natural circluation cooling of air. Methods: Several Computational Fluid Dynamics (CFD) based programs were employed for this research. Firstly, Pro/ENGINEER was applied to establish the 3D model of the CRDM group; then the geometrical model was meshed with ICEM; finally, the flow field and temperature distribution were solved by using FLUENT. Results: The temperature field of the CRDM can be divided into three regions, and the temperature of the middle CRDM was highest, while the temperature of the region between the middle and outside regions was lowest due to the relative weak convection. The highest coil temperature is 198 °C, below the limit value of 200°C. Conclusion: The CRDM and the coils may be cooled effectively by natural convection of air under given conditions.Cited
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发布时间：2021-03-03 - 摘要：Background: In order to change the status that nuclear power software technology lags behind the foreign countries, the thermal-hydraulic safety analysis program COSINE is being developed. Purpose: To complete the solution of the hydraulics equation, a fully considered model of detailed vapor and liquid interphase friction was proposed. Methods: With reference to some mature interphase friction models, we developed the FORTRAN program for the model and designed appropriate numerical routines to test the model. And the RELAP5/Mod3.2 was applied to results comparison of the rationality and accuracy of the model. Results and Conclusion: The results show that the model is valid and the program can run normally.Cited关键词：Thermal hydraulics analysis;Interphase friction;Model development;Program test
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