最新刊期
      卷 39 ， 期 9 ， 2016

        NUCLEAR PHYSICS, INTERDISCIPLINARY RESEARCH

      • Huaqing ZHENG,Bin LI,Jing SONG,Lijuan HAO,Pengcheng LONG,Liqin HU,Yican WU
        Vol. 39, Issue 9, Article number: 090502(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090502
        摘要：BackgroundIn the radiation shielding analysis of advanced nuclear reactor with Monte Carlo method,it is one of the researches focuses on using variance reduction methods more effectively. PurposeAn adaptive variance reduction method based on automatic mesh generating and weight window smoothing is developed in this paper. MethodsWith hybrid calculation of Monte Carlo method and deterministic theory,consistent adjoint driven importance sampling(CADIS)method was developed by automatic mesh generating with computer aided design(CAD)and pre-calculation of free path.The adjoint flux calculation results with deterministic method are treated as core values to generate source biasing parameters and weight window parameters in the form of mesh.And smooth treatment is introduced for alleviating the lower bound of weight window violent change to make sure the efficiency of particle bias in different areas and improve calculation efficiency.This method can solve the convergence problem in Monte Carlo simulation with large space geometry. ResultsThe adaptive method has been applied in the shielding calculation of China lead-based reactor(CLEAR)cover with complex geometry and massive shielding body.The result showed that the computing efficiency is improved by nearly 10 times. ConclusionThe adaptive variance reduction method can be applied to the shielding calculation of advanced nuclear fission reactor.  
        关键词：Monte Carlo;Hybrid calculation;Variance reduction;Radiation shielding   
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        发布时间：2021-05-24
      • Lianjing QIN,Meili LI,Lan JIANG,Haiqing SONG
        Vol. 39, Issue 9, Article number: 090501(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090501
        摘要：BackgroundAs an important content of radiation environmental monitoring in China,the atmospheric aerosol radioactive level has attracted much attention. PurposeThis study aims to find out variation regularity and affecting factors of radionuclide concentrations in atmospheric aerosol. MethodsThe radioactivity concentrations of total α,total β,210Pb,210Po and 7Be in the atmosphere of Guangzhou urban were determined from January 2014 to December 2015. ResultsThe annual average concentrations of total α,total β,210Pb,210Po and 7Be were 0.12mBq·m-3,0.75 mBq·m-3,0.93 mBq·m-3,0.23 mBq·m-3,3.16 mBq·m-3,respectively.All of the minimum monitoring data occurred in September,however,the lowest activity period for each item was not the same,and the total α,total β appeared in November,210Pb,210Po appeared in February,and 7Be was in January. ConclusionThe radioactivity concentrations reflected obvious seasonal trends.210Pb,210Po and 7Be had the strong correlation with PM10 and PM2.5.210Pb,210Po intended to be absorbed on PM2.5 rather than PM10,while 7Be showed an opposite result.  
        关键词：Atmospheric aerosol;Radioactivity concentration;Correlation;PM10;PM2.5   
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        发布时间：2021-05-24

        NUCLEAR ENERGY SCIENCE AND ENGINEERING

      • Lu LU,Limin ZHENG
        Vol. 39, Issue 9, Article number: 090603(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090603
        摘要：BackgroundThe main design feature of Generation Ⅲ passive power plant is that the passive safety principles are adopted,so the system,equipment and structure are simplified significantly,and the plant safety,reliability and economy are greatly improved.And the utility requirements document(URD)requirements are met by Generation Ⅲ passive power plant. PurposeIn this paper,a calculation is made to analyze and verify that the requirement in URD volume Ⅲ chapter 5 which is related to the automatic depressurization system(ADS)function is met.The requirement is that sufficient reactor coolant system(RCS)inventory and/or makeup shall be provided so that ADS initiation shall not be required for 8-h following a small leak of reactor coolant system,i.e.,2.27-m3·h-1 of cold fluid in excess of available charging capacity. MethodsThe small break loss of coolant accident(LOCA)safety analysis code NOTRUMP is used in this calculation.And NOTRUMP is a one dimension,system analysis code. ResultsThe results show that the core makeup tanks(CMTs)remain in recirculation phase during the 2.27-m3·h-1 leak of RCS transient.The water levels in CMTs do not decrease,and the ADS are not actuated accordingly. ConclusionThe URD requirement described above that ADS initiation shall not be required for 8-h following a small leak of reactor coolant system,i.e.,2.27-m3·h-1 of cold fluid in excess of available charging capacity is met for AP1000 nuclear power plant.  
        关键词：RCS leak;ADS;URD   
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        发布时间：2021-05-24
      • Shuai WANG,Changhong PENG,Yun GUO
        Vol. 39, Issue 9, Article number: 090601(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090601
        摘要：BackgroundMelting process is very complex in serious accident of reactor.However,because of the complex structure and materials,it is too hard to investigate the phenomenon directly. PurposeThis paper aimed at clarifying the factors affecting the melting process. MethodsA simple melting process of phase change materials(paraffin)inside a cylindrical container is presented experimentally in this study.Under different boundary conditions of the cylindrical outside surface,paraffin was heated to melt by the heating rod placed in the center of the cylindrical container. ResultsPhase front and liquid fraction during the melting process are obtained by interpolation method. ConclusionDue to heat conduction in early stage,paraffin near heating rod begins to melt,and then the generation and intensification of natural convection accelerate phase change in the upper region of the cylinder,causing significant temperature stratification in the upper region.Moreover,temperatures flat phenomena at some positions are described and discussed in detail.Besides,the effect of different heating power and boundary conditions on melting rate is compared,as well as the temperature of water bath.  
        关键词：Melting process;Phase change;Paraffin;Cylindrical cavity;Natural convection   
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        发布时间：2021-05-24
      • Chun XUE,Haiqing ZHANG,Zhiyong ZHU,Jun LIN
        Vol. 39, Issue 9, Article number: 090602(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090602
        摘要：BackgroundMolten salt reactor(MSR),a fourth generation reactor,possesses good economy and inherent safety properties.By using the fuel assembly in molten-salt-cooled reactor,it is expected that the fuel load and release can be easier and reliable,which is similar to that widely used in LWR(Light Water Reactor). PurposeBased on spherical TRISO(Tristructural Isotropic)coated particle fuel elements,this study aims to design a fuel assembly model for the high-temperature molten-salt-cooled reactor. MethodsThe MCNP(A Monte Carlo N-Particle Transport Code)is employed to investigate the feasibility and behavior of the fuel assembly by analyzing the infinite multiplication factorKinf,the reactivity temperature coefficient(RTC)and the void reactivity(VR)of the FLiBe coolant as a function of the composition,density and wall thickness of the assembly material,the TRISO coated particles packing factor and the enrichment of7Li in FLiBe salt. Results and ConclusionThe results show that carbon-based materials are significantly better than silicon-carbide-based materials for fuel assembly.Increasing the TRISO packing factor and enrichment of7Li helps to improve neutron economy and security properties of the reactor.  
        关键词：MSR;Fuel assembly;TRISO particle;Reactivity temperature coefficient   
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        发布时间：2021-05-24

        NUCLEAR ELECTRONICS AND INSTRUMENTATION

      • Yingrui HU,Xiaoqiang LI
        Vol. 39, Issue 9, Article number: 090403(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090403
        摘要：BackgroundThe SPIR-IDENT(Site Protection Against Intrusion of Radioactive Material)advance spectroscopic pedestrian portal released by MGP company in recent years could detect and identify actual radiological threats in real time,but no similar domestic product with independent property rights exists in China at present. PurposeThis study aims to develop a radioactivity identifying pedestrian portal with independent property rights to enhance the ability of protection against radiological threats,such as intrusion of special nuclear materials or radiological dispersion devices into critical infrastructure. MethodsA 2-L NaI detector is employed to connect with a large scale Field Programmable Gate Array(FPGA)based digital processing system.Digital trapezoidal filter,spectroscopy processing block including spectroscopy composition,smoothing and peak-seeking were implemented in a single FPGA,and a μC/OS-Ⅱ soft-core was imported to perform digital spectroscopy stabilization,nuclide identification and classification in this FPGA.The spectra processing method was optimized by using hardware multiplier and hardware divider to improve the algorithm speed to satisfy the system requirement. ResultsExperimental test shows that the radioactivity identifying pedestrian portal can detect and discriminate radioactive at the distance of less than 1m from the center point of detector within 1 s.The energy resolution is 7.44% @662 keV and the minimum detectable activity is 41.9 kBq. ConclusionWith the large scale embedded FPGA technology and the nuclear pulse digitized processing and shaping technology,a bulk volume NaI detector can be used to implement an effective radioactivity identifying pedestrian portal.  
        关键词：NaI detector;Embedded FPGA;Isotope identification;Minimum detectable activity   
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        发布时间：2021-05-24
      • Jiaqing YAN,Yuguang XIE,Tao HU,Junguang LYU,Li ZHOU
        Vol. 39, Issue 9, Article number: 090402(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090402
        摘要：BackgroundThe thick gaseous electron multiplier(THGEM)is homemade with the hole diameter of 150μm,pitch of 400μm,and thickness of 100μm. PurposeA THGEM-based 2D position detector is developed for low energy electron detection. MethodsThe influences of film's thickness,air-layer's thickness,etc.,on the electron transfer efficiency and transverse diffusion were simulated by Geant4 and using the 5.9-keV X-rays,and the gas gain,energy resolution were measured in different gas mixtures. ResultsAccording to the simulation results,the design and structure of the detector were optimized and the maximum gas gain of single and double layer THGEMs reached 1×104 and 6×104,respectively,and the energy resolution was higher than 23% for both single-and double-layer THGEMs. ConclusionThe spatial resolution is required less than 200μm in 50mm×50mm sensitive area.  
        关键词：THGEM;Low energy electron;2D position   
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        发布时间：2021-05-24
      • Yichao MA,Na ZHU,Hongshe DANG,Sen QIAN,Wenjing BAI
        Vol. 39, Issue 9, Article number: 090401(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090401
        摘要：Background:Many performance parameters of photomultiplier tube(PMT)are tested on the basis of the single photoelectron spectroscopy,so single-photon source is essential to the batch test of PMT and requirements of light source for precise single photo electron spectrum measurement.Purpose:The study aims to design a single-photon pulse generator used in batch test for PMT.Methods:A control panel for the adjustable pulse signal generator with multi-channel output is designed and implemented after the performance test analysis of PMT.A MAX10-10M08SAE144C8G FPGA(Field-Programmable Gate Array)chip,a STM32F107 ARM(Acorn RISC Machine)controller and a DP83848 Ethernet chip are integrated to realize desired functionalities.PC sends commands to STM32F107via Ethernet;then ARM controller analyzes commands and sends them to FPGA to achieve adjustable duty cycle,and adjustable frequency,adjustable amplitude pulse output through the level conversion chip.Results:Compared with the most often used RIGOO-DG5352 signal generator,the newly-designed single-photon pulse generator showed better performance on both the fall time and the rise time.Conclusion:The output signals of this single-photon pulse generator could match the requirements in the PMT single photo-electron spectrum test.Also it can be extended to multi-channel outputs for PMT batch test.  
        关键词：PMT;FPGA;Single optical electronic test;Pulse signal generator   
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        发布时间：2021-05-24

        SYNCHROTRON RADIATION TECHNOLOGY AND APPLICATIONS

      • Ping ZHOU,Chunxia HONG,Yuzhu WANG,Chunming YANG,Feng TIAN,Fenggang BIAN,Jie WANG
        Vol. 39, Issue 9, Article number: 090101(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090101
        摘要：Background:Biological small angle X-ray scattering beamline(BioSAXS)is one of the five beams of six beamlines of Protein Science Shanghai Facility,and its motion control system and data acquisition system are important for the beamline operation. Purpose:This study aims to design and implement the motion control system and data acquisition system of BioSAXS. Methods:The synApps and motor packages of Experimental Physics and Industrial Control System(EPICS)is employed to achieve motion control system,data acquisition and control of area detector,together with the control interface for motion control,and X-ray light intensity detection,are implemented and integrated by using Control System Studio(CSS). Results:Unified user interface for beamline control and data acquisition system for BioSAXS are realized,and the system has been successfully applied to the debugging and running of BioSAXS Beamline. Conclusion:This proposed system fulfills the functions for motion control system and data acquisition system for BioSAXS.  
        关键词：BioSAXS;EPICS;CSS;Control system;Data acquisition system   
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        发布时间：2021-05-24

        NUCLEAR CHEMISTRY, RADIOCHEMISTRY, RADIOPHARMACEUTICALS AND NUCLEAR MEDICINE

      • He YANG,Hu ZHANG,Li LI,Xiaohong HUANG,Riteng WANG
        Vol. 39, Issue 9, Article number: 090301(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090301
        摘要：Background:Extraction and separation of neptunium is one of the topics focused in reprocessing.Hydrazine nitrate is often used as a cleaning agent for nitrous acid in the Purex process.In addition,due to the selectivity of hydrazine nitrate for the redox reactions of Np(VI)and Pu(IV),theoretically the difference of the reaction rate can be used to separate the neptunium from uranium and plutonium.Purpose:In order to explore the feasibility of separation for neptunium and plutonium with hydrazine nitrate,this paper adopts the single stage extraction experiments to research the process of reductive stripping of neptunium and plutonium.Methods:By investigating the effects of the concentration on nitric acid and hydrazine nitrate,as well as reaction temperature on the reductive stripping process,the Np(VI)and Pu(IV)stripping kinetics equation and apparent activation energy were determined.Further,the half reaction time of reductive stripping Np(VI)and Pu(IV)with hydrazine nitrate can be obtained by means of kinetics equation,and a preliminary exploration for Np(VI)/Pu(IV)separation was carried out.Results and Conclusion:The rate equations of the reaction Np(VI)with hydrazine and Pu(IV)with hydrazine were respectively obtained.Further,the half reaction time of reductive stripping Np(VI)and Pu(IV)with hydrazine nitrate can be obtained by means of kinetics equation,and a preliminary exploration for Np(VI)/Pu(IV)separation was carried out  
        关键词：Hydrazine;Reduction stripping;Separation of neptunium and plutonium   
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      • Dan MENG,Weijuan WANG,Wei WEN,Yang DU,Yinhang ZHOU,Zhaoyi TAN,Heyi WANG
        Vol. 39, Issue 9, Article number: 090302(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090302
        摘要：Background:In the environment tritium exists primarily as tritiated water(HTO).However,tritium can also be incorporated into organically bound tritium(OBT)in plants and animals,and the OBT of environmental organisms can reflect the environmental tritium level.Purpose:In order to accurately evaluate the level of tritium in the biological environment,the furnace of tritium-carbon oxidation burning-pyrolyser pyrolysis has been developed to analyze the OBT activity of environmental plant on the base of the principle of high temperature catalytic oxidation.Methods:In this paper,the preparation condition of the pyrolyser-furnace was optimized through a lot of experiments,and the uncertainty of OBT in typical plant was studied.Results:The results indicate that the optimum preparation conditions of OBT in plant are with the oxygen flow rate of the working tube at 100 mL·min-1,the catalytic oxidation temperature at 800°C and the combustion temperature at 600℃.At this point,the recovery rate of combustion for different samples was kept above 85%.Conclusion:The sample preparation process of optimized condition is more secure and the combustion of plant sample is more complete,which completely meet the requirement of OBT analysis in environmental plant,and this method can be used in the tritium level measurement and evaluation in the environmental organism.  
        关键词：Organically bound tritium;Tritium-carbon oxidation burning furnace;Preparation condition   
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        发布时间：2021-05-24

        LOW ENERGY ACCELERATOR, RAY AND APPLICATIONS

      • Le ZHENG,Jidong LONG,Pan DONG,Zhaohui LAN,Yufei PENG
        Vol. 39, Issue 9, Article number: 090204(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090204
        摘要：Background:The metallic hydrogen(deuterium)electrode vacuum arc ion source which can discharge plasma mainly containing metal ions,hydrogen ions and deuterium ions,is generally used to the ion gun or the small accelerator.Purpose:To study the deuterium ions ratio affected by the arc current,the deuterium ion ratio produced by the discharge of vacuum arc ion source with metallic deuterium electrode was measured.Methods:To separate metal ions,hydrogen ions and deuterium ions,the magnetic analysis was used.And the ions current was measured by the scintillators and Faraday cups.Results:Experimental results showed that,within a certain range of arc current,the greater the plasma density is,the change of plasma emission surface affected the collective of ions current more obviously.And within the range of 30-80 A,deuterium ion ratio increased with the arc current,but the ratio became stable when arc current exceeded 60 A.Conclusion:The magnetic analysis platform can be used to obtain the deuterium ions ration of vacuum arc ion source.Within a certain range of arc current,the arc current can increase the deuterium ions ratio.  
        关键词：Vacuum arc;Metallic hydrogen;Ion source;Ion species   
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      • Chenglong LI,Zhenxing TANG,Yuanji PEI
        Vol. 39, Issue 9, Article number: 090203(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090203
        摘要：Background:The development of high performance electron beam source has been a challenge for Free-electron Laser(FEL)based THz source which is critical for the energy,energy spread and emittance of the electron beam.Purpose:This work aims to find out the mechanism of emittance growth and developing a compensation technique for this emittance growth in the Radio Frequency(RF)gun cavity.Methods:First of all,a RF gun cavity is designed using POISSON Superfish to calculate its electro-magnetic field distribution for analysis of the emittance growth mechanism.Then,a compensation scheme is developed by employing a pair of solenoids to reduce the space charge emittance.Finally,the effectiveness of scheme is evaluated using the commonly used reliable simulation program ASTRA.Results:The simulation results show that the normalized transverse emittance of a 5.67-MeV electron bunch with 200 pC is reduced to 0.373 mm·mrad while the energy spread is reduced to 2.3‰.For a 5.67-MeV electron bunch with 1000 pC,the emittance and energy spread are reduced to 0.934 mm·mrad and 7.6‰,respectively.Conclusion:Simulation of the final design shows that the performance of the electron beam produced by the RF gun has achieved the requirements for THz source.  
        关键词：High quality electron beam source;Photocathode RF gun;Emittance;Compensation solenoid;Space charge force;Energy spread   
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      • Chao ZHAO,Zhen YANG,Fangdong TANG,Linfeng HE,Yihe XU,Xiaojun LU
        Vol. 39, Issue 9, Article number: 090201(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090201
        摘要：Background:With the development of the nuclear safety technology in China,more and more environmental gamma radiation dose rate meters were fixed in the field to monitor the environmental radiation in real time.Calibration of these meters is inconvenient to do on-site.Purpose:This study aims to design and implement a portable irradiation device for on-site calibration of these dose rate meters.Methods:An irradiation collimator was designed through Monte Carlo simulation as the kernel component of the irradiation device,and an automated supporting platform with functionalities of ranging,shifting,switching attenuation plates and remote control of intensity and position was developed as the additional component.Experiments and Monte Carlo simulations were conducted to test the performance of the irradiation device and calibrate the air kerma rate in the radiation filed of it.Field-testing was also performed to check the practicability of this irradiation device on condition of on-site calibration.Results:The adjustable range of the air kerma rate in the reference radiation filed was 0.27-34.86μGy·h-1.The self-developed irradiation device had good performance on reproducibility,self-scattering,homogeneity and practicability in field application.Conclusions:A portable irradiation device was designed and developed through Monte Carlo simulation for the calibration of on-site dose rate meter,it can be used to achieve the traceability of the fixed environmental gamma radiation dose rate meter.  
        关键词：On-site calibration;Irradiation device;Irradiation collimator;Scattering;Homogeneity   
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      • Yajun JIA,Yongjiang LI,Xiao ZHANG,Xiaoying MA,Chao WU,Ming LYU,Yuehu PU
        Vol. 39, Issue 9, Article number: 090202(2016) DOI: 10.11889/j.0253-3219.2016.hjs.39.090202
        摘要：Background:Particle beam therapy has been proved to be an effective and important method for treating cancer patients.There are more than 60 particle beam treatment centers in the world according to recent statistics.At Shanghai Institute of Applied Physics(SINAP),the first domestic prototype of a proton treatment system based on synchrotron accelerator is being developed.In order to optimize the system design for future development and estimate the performances of the prototype therapy machine using advanced active beam scanning techniques,a sophisticated simulation tool is needed.Purpose:The primary goal is to develop a computer code which can simulate the irradiation process for treating typical static and moving targets by using beam scanning technique.Using the developed code,detailed case studies will be performed to gain insights of the impacts of various machine parameters on the final dose distributions.Methods:The simulation code is composed of three major parts,namely the data preparation,irradiation action simulation,and weighted superposition of the dose contributions from all tens of thousands of scanned beam spots.The data preparation includes reading accelerator beam and scanning parameters,generating 3-dimensional(3D)energy-normalized Bragg curve,allocating scanning beam spots inside the target volume,preparing relative beam weights of each scanning beam spot and computing the absolute particle number to be irradiated to each beam spot.Then scanning irradiation is simulated by a spot-wise time integration of the beam spills mocking the function of a beam dose monitor taking the respiratory gating and all the time delays encountered in the scanning system into account.Multi-threading parallel computing is used to speed up the simulation process.Results:Using the developed simulation code,irradiation processes with discrete spot scanning technique of a static and another moving rectangular target inside a water phantom are successfully simulated.With assumed parameters including scanning speeds,beam current time structure,beam shutoff time delay,scanning spot pitches,prescribed dose,homogeneous 3D dose distributions conformal to the target volume can be obtained.The simulation also shows that beam shutoff time on the order of 200 μs can significantly spoil the dose distribution due to larger delivered number of particles to each beam spot as compared with the planned values unless the beam current from the accelerator is kept sufficiently low.The code shows that in irradiation of a moving target,both the beam gating method and careful selection of faster scanning direction are very effective methods to reduce the interplay effects caused by the motions of the scanning beam and the target.Dose rate and total irradiation time of treating a given target under realistic beam and scanning parameters are easily obtained.Using an 8 core Intel i7-4790 CPU PC,the simulation takes typically 1.5 h for the studied cases.Conclusions:A useful simulation code is successfully developed and used to study scanning irradiation of static as well as moving targets.Impact of beam switching-off response time and beam intensity on the 3D dose distribution is quantitatively clarified.These results will be considered in works aiming at optimizing the design parameters of new proton therapy systems.It is also shown that respiratory gating technique can effectively mitigate the influence of target motion and distinctly improves the dose distribution.Future research will focus on refining the simulation models and introducing GPU based parallel computing to shorten the time needed for carrying out the simulations.  
        关键词：Proton therapy;Spot scanning;Bragg curve respiration gating;Dose distribution;Beam shutoff delay;Simulation   
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