最新刊期
      卷 41 ， 期 9 ， 2018

        NUCLEAR ELECTRONICS AND INSTRUMENTATION

      • Chaoming SUN,Jiqiang GE,Kaihua SUN
        Vol. 41, Issue 9, Article number: 090401(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090401
        摘要：BackgroundTo a great extent, the acquired image quality in digital radiography depends on the calibration status of digital X-ray detector.PurposeIn order to avoid fluctuation or deterioration of the image quality, the calibration and performance optimization of digital X-ray detector were studied.MethodsThe detector calibration procedure and signal transformation process inside the detector were analyzed, then a series of calibration tests by changing the X-ray energy and its intensity were carried out.ResultsThe tests show that non-uniformity among pixels of the detector is obviously suppressed after effective calibration and gray values of the image are distributed uniformly. If the X-ray intensity is higher in the calibration process, signal noise ratio (SNR) of the calibrated image will be higher accordingly, thus the image quality will be improved. If X-ray energy of the calibration process equals to that of radiographic testing, the output of detector will be calibrated well.ConclusionAfter analysis of the tests, we know that the key to optimize the correction method of the digital detector is to choose an appropriate calibration factor. For the image from a detector of not well calibrated, measures still can be adopted to improve the image quality as follow. The deteriorated image should be restored to a detector response under certain exposure, and then the response can be used to perform a good calibration with another appropriate calibration factor.  
        关键词：Digital radiography;Flat panel detector;Calibration;Image quality   
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        发布时间：2021-05-19
      • Lin CHAI,Han WANG,Jialing WU,Weiwei QU,Wanxin WEN,Gaolong ZHANG
        Vol. 41, Issue 9, Article number: 090403(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090403
        摘要：BackgroundWith the development of semiconductor photon detector technology, a novel signal readout device named multi pixel photon counter (MPPC) has gradually been developed and applied in radiation detection. PurposeThis study aims to verify the performance of the MPPC and compare it with photomultiplier tube (PMT) in linearity and energy resolution. MethodsFirst of all, scintillation detectors with MPPC coupling with scintillation crystals such as thallium-doped sodium iodide (NaI(Tl)), CsI, and Bi4Ge3O12(BGO) crystals was constructed to test three characteristic γ-ray energy peaks of 137Cs and 60Co. Then the same tests were done with PMT (Hamamatsu H7195) coupling with these crystals as the parallel experiments. Simultaneously, the output signal of the MPPC was collected by using a waveform digitizer (CAEN DT5730) and a self-made pre-amplifier. ResultsThe results show that the MPPC has a slightly worse energy resolution compared to that of PMT, but reserves a similar energy linearity. ConclusionThis MPPC could be applied in circumstances such as the space detection and medical applications instead of PMT.  
        关键词：Multi-pixel photon counter;Energy resolution;Linearity;Scintillation crystal;Waveform digitizer   
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        发布时间：2021-05-19
      • Qiang HUANG,Lei YANG,Zhen CHEN,Xiaoheng XU,Mengchao ZHANG,Dongcang LI
        Vol. 41, Issue 9, Article number: 090402(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090402
        摘要：BackgroundThe pile-up effect of stochastic pulse could have detrimental impact to the nuclear energy spectrum acquisition system, and make the relevant nuclear energy spectral resolution even worse at high count rates. Purpose & MethodsIn order to restrain the adverse effect, we proposed pulse-width analysis method, which was based on the high speed digital sampling technique of full-pulse waveform, to real time distinguish and reject nuclear pulse pile-up signals at high count rates. In this sense, experiments were performed from both signal source and radioactive source to verify this method. ResultsThe feasibility of this method had been proved on the basis of signal source of imitating nuclear radiation pulse. In the meantime, the γ rays of 60Co and 137Cs radioactive source were measured by using NaI scintillation detector under the experiment platform. ConclusionThe results illustrate that pulse-width analysis method can continuously monitor the situation of pulse post-stacking events and leading-edge stacking events, and also has significant effect on improving the resolution of digital γ spectrometer at high count rates.  
        关键词：Pile-up discrimination;Pulse-width analysis;High count rates;Digital γ spectrometer   
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        发布时间：2021-05-19

        LOW ENERGY ACCELERATOR, RAY AND APPLICATIONS

      • Chunlong YAO,Zhejie ZHU,Jianjian SHI,Xuehui XU,Yichu WU
        Vol. 41, Issue 9, Article number: 090201(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090201
        摘要：BackgroundMagnesium hydroxide and magnesium oxide are both important metal compounds with many excellent properties which make them have great application prospects in various fields of industry and environmental protection, such as flame-retardant, antibacterial agents, water/gas treatment, catalysts. PurposeThis paper focus on analysis of the microstructure of magnesium hydroxide at different calcining temperatures, especially the changes of vacancy clusters and pores before and after phase transition temperature. MethodsNano-magnesium hydroxide was prepared by direct precipitation method with the addition of polyethylene glycol (PEG) surfactant and nano-magnesium oxide was obtained by calcining nano-magnesium hydroxide. The microstructure and defects of both magnesium hydroxide and magnesium oxide were investigated by positron annihilation lifetime spectroscopy (PALS), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), field emission scanning electron microscopy (FESEM) and nitrogen adsorption-desorption experiment. ResultsThe original magnesium hydroxide particle prepared by direct precipitation method has flake -like morphology with about 15 nm thickness. Corresponding magnesium oxide is a sphere-like particle with a size of about 30 nm and good dispersivity. The positron lifetime measurement found that two long lifetime components τ3 and τ4 reflect the information of micropores and mesopores in the samples, respectively. When the nano-magnesium hydroxide transformed to nano-magnesium oxide in the temperature range of 250~300℃, relative intensity I4 increases significantly and I3 decreases rapidly, indicating that the number of mesopores increases suddenly, while the number of micropores decreases rapidly. The pore size calculated by the improved Tao-Eldrup model is consistent with the pore size (2~4 nm) measured by nitrogen adsorption-desorption experiment. ConclusionFlake-like nano-magnesium hydroxide was synthesized by precipitation method with the addition of PEG surfactant. Sphere-like nano-magnesium oxide was obtained by calcining nano-magnesium hydroxide in the temperature range of 300~700℃. During the phase transition from nano-magnesium hydroxide to nano-magnesium oxide, a large number of micropores are migrated and integrated into larger mesoporous pores because of growth and recombination of the grain. On the other hand, the removement of water molecules promotes formation, migration and aggregation of the vacancy clusters and microvoids.  
        关键词：Positron annihilation;Magnesium hydroxide;Magnesium oxide;Phase transition;Pore   
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        发布时间：2021-05-19
      • Su XU,Qingxian ZHANG,Qingju HE,Tao WU,Gang ZHANG,Cong SHI,Kun SUN,Yunlong XIAO
        Vol. 41, Issue 9, Article number: 090203(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090203
        摘要：BackgroundNeutron depth profiling (NDP) method is widely used in semi-conductor production, ion implantation research, material science and other fields. PurposeThis study aims to explore the reliability of simulation software in NDP energy spectrum analysis, and compare the results of simulating NDP by SRIM, MCNP, FLUKA, and GEANT4. MethodsFirst of all, the differences of four software in simulation for alpha spectrum are discussed. Then, the experimental alpha spectrum of National Institute of Standards and Technology (NIST) standard is used to evaluate the simulation results of MCNP, FLUKA and GEANT4 in NDP analysis. ResultsThe simulation results of alpha spectrum show that the peak position of alpha spectrum is close to each other when the thickness of silicon is less than 2μm. ConclusionsThree software, i.e., MCNP, FLUKA and GEANT4, could be used to simulate the alpha spectrum in NDP analysis whilst the MCNP achieves better accurate full width at half maximum (FWHM) and the peak position of alpha spectrum.  
        关键词：Neutron depth profiling;FLUKA;GEANT4;MCNP;SRIM;SRM2137   
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        发布时间：2021-05-19
      • Jincheng JIA,Xiaolong LI,Wu LU,Jing SUN,Xin WANG,Mohan LIU,Xinyu WEI,Shuai YAO,Qi GUO
        Vol. 41, Issue 9, Article number: 090202(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090202
        摘要：BackgroundBipolar junction transistors (BJTs) in spacecraft may be damaged by ionizing radiation.PurposeThis study aims to investigate the dose rate effect and the radiation response of the voltage comparator.MethodsTypical bipolar voltage comparators LM339 of the same batch produced by Texas Instruments (TI) are irradiated by 60Co-γ at high-and low-dose-rate under different bias conditions. Some parameters of the voltage comparator subjected to ionization radiation, such as input bias current, open loop gain and low-level output voltage, are observed. The changing law of sensitive parameters of voltage comparator and the concrete degradation mode in the circuit level are analyzed.ResultsThe degradation in performance of voltage comparator corresponding to low rate dose irradiation exhibits more dramatically enhancement, i.e. enhanced low dose rate sensitivity.ConclusionsThe radiation response of the voltage comparator is severely affected by the bias conditions.  
        关键词：Bipolar voltage comparator;60Co-γ irradiation;Dose rate effect   
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        发布时间：2021-05-19

        NUCLEAR PHYSICS, INTERDISCIPLINARY RESEARCH

      • Bing JIANG,Zeen YAO,Wei WEN,Tie HE,Guangyi ZHAO,Li AN
        Vol. 41, Issue 9, Article number: 090503(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090503
        摘要：BackgroundThe measurement of tritium production rate for tritium breeding blanket is one of the important issues that to be studied in fusion nuclear power system. PurposeA preparation method of liquid scintillation sample for lithium carbonate probe was developed for the measurement of tritium production rate. Methods & ResultsThe results showed that the method of dissolution of lithium carbonate by hydrochloric acid can produce high transparency and no liquid scintillation sample layer. ConclusionCompared to other mixed acid treatments, this method reduces the steps for finding the optimum volume ratio of the mixed acid, and simplifying the preparation of liquid scintillation samples of lithium carbonate pellets. The study of the refining process shows that in a 20 mL liquid scintillation measuring vial, the volume of liquid scintillation fluid is at least 10 mL and the volume of hydrochloric acid should not exceed 0.2 mL for the volume of hydrochloric acid which can just dissolved the lithium carbonate pellet. The compatibility of the liquid sample prepared by this method is stable for a long time, but the degree of quenching will vary. The effect of quenching changes on tritium measurement should be taken into account.  
        关键词：Tritium production rate;Lithium carbonate pellet;The preparation of liquid scintillation sample;Compatibility;Stability   
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        发布时间：2021-05-19
      • Lijun XU,Hongsheng YE,Lijun DIAO,Weidong ZHANG,Rui LUO,Ming LI,Min LIN,Xinpeng SONG,Wen XIA,Yizhen CHEN,Zhenhong XIAO,Kesheng CHEN
        Vol. 41, Issue 9, Article number: 090502(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090502
        摘要：BackgroundUnder the condition of nuclear accident, the distribution of radioactivity in the boundary soil is difficult to be determined. It is necessary to develop a reference soil that has a variety of radionuclides such as 60Co, 90Sr, 137Cs, 241Am, and so on. PurposeDue to the fact that the soil contaminated by accidental radioactivity is difficult to find, it is proposed to use artificial addition of radionuclides to prepare the reference soil. MethodsThe difference in the local composition of the soil and the difference in particle size with respect to the adsorption of radionuclide may form a so-called "hot spot", resulting in inhomogeneity. In order to solve this problem, three nuclides 60Co, 90Sr and 137Cs are selected for the preparation with stepwise addition method. ResultsThree groups and eighteen times of measurement data for each nuclide were calculated in a homogeneity test with F-value exam. The result is F ≤ Fα, which meets the requirements. ConclusionThe homogeneity of the reference material can be solved by an improvement method:1) changing the aqueous solution to an organic-aqueous solution in the first step of mixing; 2) using a ball milling mixing method instead of the three-dimensional mixing method in the mixing of the soil powders.  
        关键词：Reference material;Radioactive "hot spots";Mix;Homogeneity;Test   
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        发布时间：2021-05-19
      • Xingya WANG,Wei XIAO,Lijuan ZHANG,Xingyu GAO
        Vol. 41, Issue 9, Article number: 090501(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090501
        摘要：BackgroundStyryl phosphoric acid (SPA) is considered to be one of the best selective collectors for rutile flotation. However, high consumption and considerable environmental pressure have limited its wide applications. PurposeIn this research, n-nonyl alcohol (NNA) was used as the auxiliary collector to reduce SPA dosage. ResultsThe experimental results indicated that when SPA was used as the single collector, the rutile flotation presented an optimum index of recovery being 52.26% and the grade being about 45% with a SPA concentration of 0.8×10-4 mol·L-1. But when 0.4×10-4 mol·L-1 SPA and 0.4×10-4 mol·L-1 NNA were used as the mixed collectors, the recovery increased to 82%, and the grade reached 47%. The obtained flotation indexes of the mixed collectors were obviously superior to those of the single collector, and the dosage of SPA in the mixed collectors was only half of that in the single collector. MethodsThe synergistic adsorption mechanism was investigated by Zeta potential measurements and Fourier Transform Infrared Spectrometer (FT-IR) analysis. ConclusionNNA increased the foam amount and improved its stability, and quickly reduced the surface tension of the solutions; SPA adsorbed first on the rutile surface, and NNA then bound to SPA by hydrogen bonding.  
        关键词：Rutile flotation;Synergistic adsorption;Foam property   
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        发布时间：2021-05-19

        NUCLEAR ENERGY SCIENCE AND ENGINEERING

      • Rui CHEN,Shumin ZHOU
        Vol. 41, Issue 9, Article number: 090601(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090601
        摘要：BackgroundFor a nuclear energy system with fast neutron spectrum, the cross section in unresolved resonance energy region is affected by the temperature effect and changes, hence, it is not possible to accurately obtain the section of each energy corresponding to the resonance peak in the energy region. When calculating the cross sections under various temperatures, the calculation method different from the resolved resonance energy region must be taken. PurposeThis study aims to propose a novel multi-temperature cross section generation method to improve efficiency with given accuracy. MethodsBased on the investigation of the status of the worldwide on-the-fly nuclear cross section generation methods for the unresolved resonance energy region in Monte Carlo neutron transport, the Neville interpolation is used for better efficiency according to the cross section features of probability table at different temperatures. This multi-temperature cross section generation method was verified on two publicly available reactor core models. ResultsPerformance test results on international fast reactor core models, i.e., Bigten1 and Bigten2, show that the deviation of the method and the reference value is less than 10 pcm, which proves the accuracy and effectiveness of the method. ConclusionThe accuracy and effectiveness of this proposed method showed its applicability for reactor multi-physical coupling simulation.  
        关键词：Neutron cross section;Monte Carlo;Unresolved resonance energy region;Neville interpolation   
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        发布时间：2021-05-19
      • Chundong HU,Mengting LI,Yahong XIE,Yuqing CHEN
        Vol. 41, Issue 9, Article number: 090603(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090603
        摘要：BackgroundChina fusion engineering test reactor (CFETR) neutral beam injector (NBI) prototype is being actively designed and built. The radiation will be generated during the operation of the prototype. In order to ensure the safety of staff, it is very important to analyze the radiation and types and design the radiation shielding at the design stage. PurposeTo study the radiation dose of the CFETR neutral beam test facility with hydrogen beam energy of 200 keV. MethodsAccording to the established model of physics parameter and geometry, the radiation dose of the key points of the negative ion based neutral beam injector system with the beam energy of 200 keV was simulated by Monte Carlo N particle transport code (MCNP). ResultsThe vacuum wall has some self-shielding effects, but it does not decrease the dose to the dose limits setting by the International Atomic Energy Agency (IAEA). ConclusionThis result can provide important reference for the design of radiation shielding for CFETR neutral beam system.  
        关键词：CFETR neutral beam test facility;MCNP;Radiation dose   
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        发布时间：2021-05-19
      • Cheng HOU,Tao YU,Jinsen XIE,Wenjie ZENG,Zhenping CHEN,Qin XIE,Zijing LIU,Pengcheng ZHAO,Lihua HE
        Vol. 41, Issue 9, Article number: 090602(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090602
        摘要：BackgroundAccording to the quasi-static method, the kinetic parameters can be calculated by the convolution of the weighting function, kinetic operators and the shape function. The traditional shape function and weighting function are not suitable for kinetic analysis of source driven sub-critical system. PurposeIn order to improve the calculation accuracy and understand physical characteristics of the source driven sub-critical system better, different shape functions and weighting functions were applied to improved quasi-static method, and they were evaluated respectively. MethodsIndividually, the λ regular flux, α regular flux and the steady flux of source driven sub-critical system are adopted as the initial shape functions. Theλ-eigenequation and α-eigenequation of the critical weighting function of kinetic parameter model, and the global weighting function of kinetic parameter model are used for the weighting function. Then the kinetic parameters and the neutron kinetic results of the starting progress and beam loss conditions can be calculated in the sub-critical system. ResultsThe results of the IQS method are compared with the results obtained directly from the spatio-temporal dynamics equation. We can find that the weighting function is the dominant factor that affect the kinetic parameters and the kinetic results. And during the starting progress, the steady flux of source driven sub-critical system and the λ-eigenequation of the critical weighting function model have obvious superiority in describing the kinetic characters of the source driven sub-critical system; for the beam loss conditions, adopting the global weighting function model to calculate the weighting function is suitable for the sub-critical system. ConclusionThe phenomenon that the change of weighting function falls behind the transition of the external neutron source indicates that the extraneous neutron source's effect on neutron importance is inhomogeneous and the inhomogeneous character should be taken into consideration when optimizing the weighting function models.  
        关键词：Neutron kinetics;ADS sub-critical reactor;Weighting function;IQS method   
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        发布时间：2021-05-19
      • Zhiwei LU,Yongdong ZHANG,Lei LI,Tong LIU,Jiaxiang XUE
        Vol. 41, Issue 9, Article number: 090604(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090604
        摘要：BackgroundInert matrix dispersion pellet (IMDP), based on the fuel technology of high temperature gas cooled reactor, a type of accident tolerant fuel, takes inert material as matrix, has high thermal conductivity compared to UO2. PurposeIn this study, effect of temperature, burnup, thermal barrier between tristructural isotropic (TRISO) and matrix on the effective thermal conductivity (ETC) of the IMDP is studied by finite element analysis (FEA) method. MethodsA FEA model is developed by ABAQUS combined its secondary development function. ResultsThe ETC of IMDP decreases as temperature and burnup increases. Under normal operation condition, the centerline temperature of IMDP is 400℃ or more lower than UO2. When the thermal barrier between TRISO and matrix increases from 0 to 4×10-4 m2·℃·W-1, the ETC of IMDP decreases approximately 16% and 19% respectively at beginning of life (BOL) and middle of life (MOL). ConclusionsIMDP has superior heat transfer performance than UO2. Thermal barrier between TRISO and matrix has more significant impact on BOL IMDP than MOL IMDP. Thermal barrier between 0 to 4×10-4 m2·℃·W-1 has more significant impact on ETC of IMDP than other values.  
        关键词：Accident tolerant;Inert matrix;Nuclear fuel;Heat transfer   
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        发布时间：2021-05-19

        NUCLEAR CHEMISTRY, RADIOCHEMISTRY, RADIOPHARMACEUTICALS AND NUCLEAR MEDICINE

      • Ying YUAN,Siguang WANG
        Vol. 41, Issue 9, Article number: 090301(2018) DOI: 10.11889/j.0253-3219.2018.hjs.41.090301
        摘要：BackgroundPandaX-Ⅲ is designed to search for the neutrinoless double-beta decay (0υββ) with high pressure136Xe gas time projection chambers at the China Jinping underground laboratory (CJPL). This rare decay can be easily covered by background, so ultra-low-background materials should be chosen as the construction for PandaX-Ⅲ. PurposeThis work attempts to establish a method to determine Th and U in copper based on inductively coupled plasma mass spectrometry (ICP-MS). MethodsThe samples were digested by 8 mol·L-1 HNO3. 230Th and 235U were spiked in the digestion solution for quantitative analysis. TEVA resin and UTEVA resin were chosen for separation of Th and U from copper. After the Th and U were pre-concentration by the resins columns, ICP-MS was applied to the determination. ResultsDetection limits of 0.036 pg(232Th)·g-1 (0.15 μBq(232Th)·kg-1) and 0.070 pg(238U)·g-1 (0.87μBq(238U)·kg-1) were achieved for blank sample, detection limits of 0.21 pg(232Th)·g-1 (0.85 μBq(232Th)·kg-1) and 0.45 pg(238U)·g-1(5.56 μBq(238U)·kg-1) were achieved for copper sample. ConclusionsThe method based on ICP-MS for the determination of Th and U in copper was presented, and can undertake the task of the radioactive assay of detector components for PandaX-Ⅲ.  
        关键词：ICP-MS;Single crystal copper;TEVA;UTEVA;Trace;Th;U   
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