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15 July 2020, Volume 43 Issue 7 Previous Issue   
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SYNCHROTRON RADIATION TECHNOLOGY AND APPLICATIONS
3D imaging of rat brain neural network using synchrotron radiation
Shuntong KANG, Tong WU, Zhuohui CHEN, Mengqi ZHANG
Nuclear Techniques. 2020, 43 (7):  70101-070101.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070101
Abstract ( 42 )   HTML ( 10 )   PDF(pc) (1359KB) ( 20 )   Save
Background

Synchrotron radiation technology has a wide application prospect. X-ray absorption contrast imaging can not only obtain the three-dimensional (3D) morphological structure of neurons, but also improve the effective spatial resolution of detection, which meets the requirements of micro-neural network imaging research. It is feasible and effective to construct high-resolution 3D visualization network of brain neural network when combined with Golgi-Cox staining.

Purpose

This study aims to explore the application of synchrotron radiation absorption contrast imaging technology in the observation of 3D imaging of Golgi-Cox-stained mouse brain micro-neural network.

Methods

Twelve normal C57 mice were randomly divided into two groups, A and B, and perfused with brain tissue. Group A was treated without staining. The brains of group B were stained with Golgi-Cox and dehydrated in gradient ethanol. Specimens were scanned for absorption contrast imaging at X-ray imaging and biomedical application beam line station (BL13W1) in Shanghai Synchrotron Radiation Facility (SSRF), and data processing was performed by using software such as Amira.

Results

The imaging results show that both the cerebellar neural network structure and single neuron morphology in mouse are accurately presented. X-ray absorption contrast imaging technology, as an advanced three-dimensional rendering method of microscopic neural network, provides a new three-dimensional visualization method for morphological research of mouse brain neurons.

Conclusions

Synchrotron radiation can achieve high-precision 3D neuroimaging, which overcomes the disadvantages of traditional staining 2D histology, such as the damage of sections to specimens. This method combined with Golgi-Cox staining, can be used for the construction of regional neural networks and non-destructive research on the integrity of the brain.

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Synchrotron radiation photoemission spectroscopy study on the phenomenon of alloying during stanene growth
Lei ZHAO, Chen LIU, Xiaoning WANG, Gholam Turghunjan, Jinmei LI, Jiali ZHAO, Yuxuan GUO, Haijie QIAN, Ibrahim Kurash, Jiaou WANG
Nuclear Techniques. 2020, 43 (7):  70102-070102.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070102
Abstract ( 37 )   HTML ( 6 )   PDF(pc) (2813KB) ( 43 )   Save
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Characterization of dermal fiber architecture based on X-ray phase contrast micro-tomography
Mingxia YUAN, Xiaowei CHEN, Bo SONG, Xiangzhi ZHANG, Hongyi LI
Nuclear Techniques. 2020, 43 (7):  70103-070103.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070103
Abstract ( 19 )   HTML ( 2 )   PDF(pc) (1770KB) ( 24 )   Save
Background

More and more studies have shown that the tissue fluid in the skin can flow along the fiber track for a long distance. This fluid flow with fiber filaments as the orbit is related to the fiber skeleton of the dermis and subcutaneous tissue layers, and the three-dimensional fiber skeleton structure has not been characterized.

Purpose

This study aims provide a high-resolution characterization method for understanding the long-range flow phenomenon of tissue fluid in the skin.

Methods

X-ray phase contrast microscopy imaging technology in the Shanghai Synchrotron Radiation Facility (SSRF) BL13W1 beamline was employed to obtain the three-dimensional fiber skeleton structure inside the dermis and subcutaneous tissue layer. Combined with computer graphics, we successfully characterized the three-dimensional fiber skeleton in human skin.

Results

It is found that the fibrous skeleton in the dermis has a long-range order and is closely related to the depth of the dermis.

Conclusions

This study provides a high resolution characterization method for understanding the long-range flow of tissue fluid in skin.

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ACCELERATOR, RAY TECHNOLOGY AND APPLICATIONS
Proposal for X-ray vortices production based on nonlinear laser Compton scattering
Heping GENG, Hailong WU, Jianhui CHEN, Zhentang ZHAO
Nuclear Techniques. 2020, 43 (7):  70201-070201.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070201
Abstract ( 36 )   HTML ( 1 )   PDF(pc) (1463KB) ( 32 )   Save
Background

An optical vortex is an electromagnetic wave with a phase that varies azimuthally along the direction of propagation. The generation and application research of X-ray vortices are becoming more and more popular in recent years.

Purpose

This study aims to propose a generation scheme of a compact and inexpensive X-ray vortices source based on nonlinear laser Compton scattering (LCS).

Methods

Laser Compton scattering (LCS) was caused by high power circularly polarized light and relativistic electron beam. This LCS provided a practical method for generating tunable, near-monochromatic, well-collimated X-rays in a compact, relatively inexpensive source.

Results

Photons with energy of 1 keV is produced by head on nonlinear LCS interaction of 6.5 MeV electron beam and 800 nm Ti: Sapphire laser beam.

Conclusions

Compared with synchrotron, X-ray vortices source based on nonlinear LCS is a compact and inexpensive source. It provides a practical method for the laboratory to research the generation and application of X-ray vortices.

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Development of data archiving and retrieval system for HLS-II based on HBase
Shangcong XIN, Xiaokang SUN, Chuan LI, Ke XUAN, Gongfa LIU
Nuclear Techniques. 2020, 43 (7):  70202-070202.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070202
Abstract ( 13 )   HTML ( 0 )   PDF(pc) (831KB) ( 9 )   Save
Background

HLS-II is a dedicated synchrotron radiation source with featured spectrum in vacuum ultraviolet and soft X-rays regions. The retrieval speed of the HLS-II historical data is critical for the performance analysis and fault diagnosis.

Purpose

This study aims to develop a HBase-based data archiving and retrieval system (HDARS) to improve the retrieval speed of HLS-II historical data.

Methods

A data extraction algorithm was designed to extract characteristic data from raw data with the different time granularities when HDARS was archiving data. The raw data and characteristic data were stored in the HBase raw data table and redundant data table, respectively. When querying long-term historical data, the proper time granularity was calculated by HDARS according to the time range of the query. Then, the characteristic data with this granularity in the redundant table were retrieved and returned.

Results

The system has been working stably since it was brought into operation. It responds to the query requests in any time range within 1 s.

Conclusions

HDARS meets all needs of HLS-II historical data query, completely solves the problem of slow retrieval of long-term historical data at a cost of small additional redundant storage space.

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A preliminary study of the performance for high energy neutron radiography convertor
Yang WU, Bin TANG, Yong LIU Bin SUN, Heyong HUO, Wei YIN
Nuclear Techniques. 2020, 43 (7):  70203-070203.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070203
Abstract ( 24 )   HTML ( 0 )   PDF(pc) (1106KB) ( 18 )   Save
Background

High energy neutron radiography is a potentially powerful method for non-destructive inspection due to the extremely high penetration depth of fast neutrons in comparison with other radiation in most materials of industrial interest. Convertor is one of the key components in a high energy neutron radiography. Plastic scintillator, fiber matrix, pressed fluorescent screen, and waveshift fiber converter, etc. can be used in a high energy neutron radiography system based on charge coupled device (CCD) camera. The performances of these convertors are different.

Purpose

This study aims at performance test of these different convertors as to determine the application characteristics or scenarios of different converters.

Methods

First of all, for the problems in the definition of the detection efficiency of traditional neutron radiography conversion screen, the definition was revised on the basic of physical principle. Then, the efficiency and spatial resolution of the three types of convertor were tested by neutron radiography experiment, and the absolute efficiency was calculated based on experimental system parameter.

Results

Pressed fluorescent screen has the best spatial resolution and waveshift fiber converter has the best absolute efficiency.

Conclusions

The waveshift fiber converter screen achieves a good balance between resolution and efficiency. Pressed fluorescent screen can be used in high-energy neutron photography scenes with high resolution requirements. The plastic scintillator is only suitable for high-energy neutron photography under the conditions of strong neutron source and large collimation ratio, and its high sensitivity to γ-rays has a great impact on imaging quality.

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NUCLEAR ELECTRONICS AND INSTRUMENTATION
Structure design of time-to-digital converter based on interconnect interpolation
Guofei YANG Hong ZHOU
Nuclear Techniques. 2020, 43 (7):  70401-070401.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070401
Abstract ( 17 )   HTML ( 3 )   PDF(pc) (1480KB) ( 21 )   Save
Background

In the all-digital phase-locked loop (ADPLL), the time-to-digital converter (TDC) is used to measure the fractional phase difference between the digital controlled oscillator (DCO) output clock and the reference clock. The higher the resolution of TDC, the better the phase noise characteristics of the loop.

Purpose

This study aims to improve the phase noise of ADPLL and enhance the resolution of TDC by using interconnect delay.

Methods

Firstly, the system structure of TDC based on interconnect line interpolation was proposed. Then, an interconnect delay method with process deviation insensitivity was implemented to realize the equal delay mechanism, and a layout structure of the ring was discussed.

Results

The experimental results show that the resolution of TDC designed by the proposed method is up to 5.35 ps in 0.18 μm CMOS process.

Conclusions

The design method of TDC based on interconnect interpolation proposed in the paper can improve the resolution.

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Study of radiation monitoring system based on fiber and pulsed-OSL technology
Wenbo LI, Dingfeng LIU, Mingming SHEN, Rongjun LI Xiaoling WU, Wenkang DENG
Nuclear Techniques. 2020, 43 (7):  70402-070402.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070402
Abstract ( 17 )   HTML ( 0 )   PDF(pc) (2384KB) ( 10 )   Save
Background

Optically stimulated luminescence (OSL) technology has recently been successfully used in the field of personal dosimetry, etc.. OSL detectors normally have the advantages of small size, strong anti-electromagnetic interference, anti-radiation, and wide dose linear range while detectors for traditional radiation monitoring system are large in size, susceptible to electromagnetic interference, and poor radiation resistance.

Purpose

This study aims to design a remote online radiation dose (rate) monitoring system based on OSL technology for diversity applications.

Methods

Al2O3:C was used as the radiation-sensitive material, with high sensitivity and long lifetime. Pulsed-OSL technology was adopted to ignore the high-intensity luminescence of the lens and fiber caused by laser exposure. Remote radiation monitoring was realized by using fiber to transmit stimulation light and OSL. The interference filter and absorbing filter were combined to block all reflected stimulation light. The OSL detector was located in the radiation field for performance test experiment, while other components were located outside the radiation field.

Results

Experimental results show that this radiation monitoring system has a dose measurement range of 79 μGy~5 Gy, energy responses (60 keV~1.5 MeV, relative to 137Cs) are within ±25% of the air kerma measurement (with endcap of 1.5 mm Fe) and ambient dose equivalent measurement (with endcap of 0.1 mm Al), while the angular response is within ±10% for 0°~135° (relative to 0°).

Conclusions

Radiation monitoring system based on fiber and pulsed-OSL technology has advantages of small-size detector, strong anti-electromagnetic interference, low detection limit, and wide measurement range, hence suitable for online real-time remote monitoring of dose (rate) in nuclear facilities such as nuclear power plant and nuclear power ship.

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NUCLEAR PHYSICS, INTERDISCIPLINARY RESEARCH
Study of neutron irradiation effects on bipolar linear regulator
Cai LI, Yiyuan WANG, Jiantou GAO, Shuai CUI, Bin CHEN, Chunlin WANG
Nuclear Techniques. 2020, 43 (7):  70501-070501.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070501
Abstract ( 6 )   HTML ( 0 )   PDF(pc) (892KB) ( 5 )   Save
Background

Bipolar linear voltage regulator is widely used in space equipment, its displacement effect needs to be evaluated due to neutron irradiation in space environment.

Purpose

This study aims at the neutron irradiation effect of bipolar linear voltage regulator under different load bias.

Methods

Neutron irradiation test was carried out on bipolar linear voltage regulators. Different load biases were applied to the components to monitor the changes of online output voltage during irradiation. Output voltage of the component was tested after irradiation under different load currents, and compared with the output voltage during online radiation test.

Results

The output voltage during irradiation decreases with the influence of the neutron, the greater the load, the more obvious the displacement damage effect. Detailed component tests under different loads after irradiation show that the difference of output voltage under different bias voltages was caused by different loads.

Conclusions

The irradiation bias has no significant effect on the displacement of the bipolar linear regulator, and the driving capability of the bipolar linear regulator reduces severely due to the neutron displacement effect, which makes it lose the load adjustment capacity. Therefore, the load should be reasonably selected for evaluation in accordance with application requirements of engineering evaluation.

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Experimental measurement study on 127Xe intercomparison sample for CTBT radionuclide laboratories
Qi LI, Yuanqing FAN, Shilian WANG, Yinzhong CHANG, Yungang ZHAO, Shujiang LIU, Huaimao JIA, Xinjun ZHANG
Nuclear Techniques. 2020, 43 (7):  70502-070502.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070502
Abstract ( 8 )   HTML ( 0 )   PDF(pc) (914KB) ( 3 )   Save
Background

Compared with four radioactive xenon isotopes (131Xem, 133Xem, 133Xe and 135Xe) involved in the comprehensive test ban treaty (CTBT), 127Xe has a longer half-life, hence is easy to be purified, and exists in environment at extremely low level. The Provisional Technical Secretariat (PTS) of the Preparatory Commission for Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) plans to conduct quality assurance activities for noble gas systems of international monitoring system (IMS) through reanalyzing the 127Xe spike samples from IMS stations in the radionuclide laboratories.

Purpose

This study aims to assess the reliability of 127Xe measurement scheme in Beijing radionuclide laboratory through the intercomparison of 127Xe radioactivity organized by PTS.

Methods

The 127Xe sample contained in the stainless steel bottle was transferred to a gas cell with carbon fiber bottom and stainless steel body. Then the 127Xe sample was measured by an HPGe detector which was calibrated the detection efficiency by the standard source accurately. The radioactivity of 127Xe was quantified by analyzing the gamma spectra.

Results

The radioactivity of 127Xe determined by this study is (53±10) Bq. The deviation between measurement result and reference value is 4.3%.

Conclusions

From the evaluation scores of this intercomparison, the accurate measurement result is achieved by Beijing radionuclide laboratory.

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NUCLEAR ENERGY SCIENCE AND ENGINEERING
Analysis and optimization of flow distribution for the reactor core of China initiative accelerator driven system
Jun WEN, Tianji PENG, Xukai FAN, Dajun FAN, Wangsheng TIAN, Dawei WANG, Long GU
Nuclear Techniques. 2020, 43 (7):  70601-070601.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070601
Abstract ( 20 )   HTML ( 1 )   PDF(pc) (1789KB) ( 21 )   Save
Background

Flow rate distribution is a significant study object in the reactor core design of China initiative accelerator driven system (CiADS). Reasonable flow rate distribution will ensure reactor core work safely.

Purpose

This study aims to optimize flow distribution in the coolant inlet area of each fuel assembly of CiADS so that the outlet temperature distribution is flat.

Method

Firstly, the top and bottom nozzle flow field were calculated by computational fluid dynamics (CFD) software. Secondly, based on the above results, the porous media model was employed to establish the flow and heat transfer analysis model of the whole reactor for numerical simulation of the flow distribution in the core, and the power coefficient was used as the reference for reactor core flow distribution.

Results

These calculation results show that the flow distribution and power coefficients are almost consistent, and the outlet temperature distribution for the fuel assemblies has been flattened. Both the pressure drop characteristics and coefficient of resistance properties of the top and bottom nozzle obtained by simulation provide the necessary parameters for analyzing the flow distribution of the core.

Conclusions

Based on the calculations, the coolant inlet area of each fuel assembly has been optimized. These calculation results show that the flow distribution and power coefficients are almost consistent, and the outlet temperature distribution for the fuel assemblies has been flattened. Thus, the fuel assembly could be operated under the safety conditions. Meanwhile, these results can provide some reference data for the subsequent hydraulic analysis.

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A numerical study of lateral compressive strength of 3D needle-punched C/C control rod guide tubes
Yuexia GUAN, Xinkuan LIU, Guangli ZENG, Yantao GAO
Nuclear Techniques. 2020, 43 (7):  70602-070602.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070602
Abstract ( 14 )   HTML ( 2 )   PDF(pc) (1390KB) ( 26 )   Save
Background

C/C composite material is one of candidate materials for molten salt reactor control rod guide tubes due to its excellent mechanical properties at elevated temperature.

Purpose

This study aims to promote the application of C/C composite in molten salt reactors, and evaluate the ultimate load and damage process of 3D needle-punched C/C guide tubes.

Methods

First of all, the ultimate compressive load of a control rod guide tube was measured by a quasi-static lateral compression experiment. Then, a three-dimensional progressive damage model of the control rod guide tube was established on the base of Tsai-Wu strength tensor theory and considering the reduction of material stiffness during progressive damage of composite materials. Based on this model, a user subroutine was developed to predict its lateral compressive strength. Finally, the ultimate bearing capacity of guide pipes of different sizes was obtained by simulation, and the quasi-static lateral compression process was simulated and compared with the experimental results.

Results & Conclusions

The numerical results show that the damage model can predict the ultimate bearing capacity of control rod guide tube. Further calculations of guide tubes of different sizes show that the ultimate load is closely related to the radius and thickness of the control rod guide tube.

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Applicability analysis of aerosol reentrainment model based on revent experiment
Liwen HE, Liqiang HOU, Lili TONG, Xuewu CAO
Nuclear Techniques. 2020, 43 (7):  70603-070603.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070603
Abstract ( 13 )   HTML ( 1 )   PDF(pc) (1027KB) ( 14 )   Save
Background

During nuclear power plant accident, operations such as containment depressurization will lead to strong evaporation of liquid. The phenomenon that aerosol in the liquid phase is entrained back into the atmosphere under the action of steam is called re-entrainment. It will increase the risk of radioactive sources leaking into the environment.

Purpose

This study aims to evaluate the applicability of Kataoka & Ishi's and Cosandey's aerosol re-entrainment models based on the Revent experiment results.

Methods

First of all, these models were converted into programming languages. Analytical models were established for the experiments, and simulation studies were carried out under experimental condition of different pressure and gas composition. Then the results of model prediction and experimental measurement were compared and analyzed to evaluate the applicability of these models for aerosol re-entrainment behaviour.

Results & Conclusions

Cosandey's model is more suitable for predicting the re-entrainment behavior of different aerosol particles in the containment during nuclear power plants accident.

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Simulation study on the characteristics of driving line rod drop based on passive acceleration
Xungang CHEN, Jintao MO, Ying LUO, Dapeng YAN, Yueyin SHEN, Haoxuan NIU
Nuclear Techniques. 2020, 43 (7):  70604-070604.  DOI: 10.11889/j.0253-3219.2020.hjs.43.070604
Abstract ( 7 )   HTML ( 2 )   PDF(pc) (1219KB) ( 18 )   Save
Background

Under the condition of tilting and swinging marine environment, the driving line of modular floating reactor (MFR) faces with a worse dropping rod environment than that under the condition of vertical fixation.

Purpose

This study aims to explore the characteristics of driving line rod drop based on passive acceleration for MFR.

Methods

First of all, a spring was added to the driving line to realize the passive acceleration rod drop. Then, the simulation study of the drop behavior of the driving line rod of MFR was carried out on the base of the existing one dimensional hydraulic simulation model of drive line rod drop and considering the influence of the spring transient force. Culation software “MATLAB” and dynamics simulation software “Motion” were combined to obtain variation curves of displacement, velocity and hydraulic force in the process of control rod dropping.

Results & Conclusions

Simulation results show that the spring has certain improvement effect on the control rod drop time, which helps to overcome the resistance when the control rod drops in the state of sloping and swing.

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Application of super-resolution optical microscopy in biology
MAO Xiuhai, DU Jiancong, HUANG Qing, FAN Chunhai, DENG Suhui
Nuclear Techniques    2013, 36 (6): 60502-060502.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.060502
Abstract404)      PDF(pc) (6093KB)(6046)       Save

Background: A noninvasive, real-time far-field optical microscopy is needed to study the dynamic function inside cells and proteins. However, the resolution limit of traditional optical microscope is about 200 nm due to the diffraction limit of light. So, it’s hard to directly observe the subcellular structures. Over the past several years of microscopy development, the diffraction limit of fluorescence microscopy has been overcome and its resolution limit is about tens of nanometers. Methods: To overcome the diffraction limit of light, many super-resolution fluoresce microcopies, including stimulated emission of depletion microscopy (STED), photoactivation localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM), have been developed. Conclusions: These methods have been applied in cell biology, microbiology and neurobiology, and the technology of super-resolution provides a new insight into the life science.

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Cited: Baidu(2)
Research status of energy dispersive X-ray fluorescence spectrometer
ZHAO Fengkui, WANG Aimin
Nuclear Techniques    2013, 36 (10): 100402-100402.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.100402
Abstract203)      PDF(pc) (1792KB)(4776)       Save

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.

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Cited: Baidu(1)
Calibration method and experiment based on I/Q demodulation principle
ZHANG Zhigang, ZHAO Yubin, XU Kai, ZHENG Xiang, LI Zheng, ZHAO Shenjie, CHANG Qiang, HOU Hongtao, MA Zhenyu, LUO Chen, MAO Dongqing, SHI Jing, WANG Yan, LIU Jianfei
Nuclear Techniques    2015, 38 (3): 30102-030102.   DOI: 10.11889/j.0253-3219.2015.hjs.38.030102
Abstract389)      PDF(pc) (1625KB)(3428)       Save
Background: In-phase/Quadrature (I/Q) demodulation technology is widely used in radio frequency signal phase control system. As the intrinsic errors in hardware, such as the imbalances of gain and phase in 90° hybrid and 0° hybrid, direct current (DC) offsets and phase errors from length difference of circuits, the output signal is an ellipse and the output phase is nonlinear to the input radio frequency (RF) signal. The detection of phase precision is influenced. Purpose: This study aims to reduce the effects of errors existed in the I/Q demodulators. Methods: A calibration method for I/Q demodulation technique is proposed and applied to research and development of I/Q integrate circuits, which is based on the surface mounted devices (SMD) chip. Results: Experimental tests showed that the phase error was less than ±0.15°, the amplitude stability was less than ±1%, and the channel delay was less than 10 ns. Conclusion: This calibration method, together with the designed circuit board for the RF signal front end preprocessing can reduce the effects of intrinsic errors efficiently. It has been being used in upgrading of beam trip diagnostic system in the storage ring of Shanghai Synchrotron Radiation Facility (SSRF).
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Cited: Baidu(2)
Thermophysical properties of liquid lead-bismuth eutectic
SU Ziwei, ZHOU Tao, LIU Mengying, ZOU Wenzhong
Nuclear Techniques    2013, 36 (9): 90205-090205.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.090205
Abstract434)      PDF(pc) (1946KB)(3218)       Save

Background: Liquid lead-bismuth eutectic (LBE) is important spallation target materials and candidate coolant materials in accelerator driven subcritical (ADS)system. Purpose: Its thermodynamic physical properties are keys to understand the basic problems in ADS R&D. Methods: By the calculation of scientific laws as well as fitting other scholars’ experimental results, we tried to obtain the above thermodynamics physical properties. Results: By the calculation, we got formula about characteristic temperatures, density, specific heat, viscosity and thermal conductivity of liquid lead-bismuth alloy. And by fitting other scholars’ experimental results, we got the fitting formula. Conclusions: Finally, by the contrast analysis, we found that the fitting formula and calculation formula agree well, and fitting formula more approaches the experimental value with a high accuracy whose differential deviation is not over 1%.

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Cited: Baidu(8)
Decay time characteristics of plastic scintillator
HUANG Zhanchang, YANG Jianlun
Nuclear Techniques    2015, 38 (6): 60203-060203.   DOI: 10.11889/j.0253-3219.2015.hjs.38.060203
Abstract450)      PDF(pc) (677KB)(2953)       Save
Background: The plastic scintillator is mostly used for the inertia confinement fusion determination systems. It is necessary to know the scintillator decay time. Purpose: The aim is to measure the decay time of the plastic scintillator and analyze the applicability of single photon method. Method: The plastic scintillator is excited by 137Cs, and the decay time of the plastic scintillator is measured by single photon method. The ST401 and EJ232 plastic scintillators are measured by this device. The theory of single photon method is analyzed via statistics and the measurement process is simulated by Monte Carlo method. Results: The results are 2.9 ns with 50 ns for ST401 and 1.6 ns with 30 ns for EJ232 via double exponential fitting. The device has a dynamic range of over 104 and an intrinsic time resolution under 0.8 ns. The experiment result agrees to the simulated one. Conclusion: The comparison between the experiment result and the simulation result indicates that with the mean counts of stop detector no more than 0.1, the result measured by single photon method can be approximated to the decay time of plastic scintillator.
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Synchrotron μ-XRF and XAFS in element distribution and speciation of air, soil and biological samples
YUAN Jing, LUO Liqiang
Nuclear Techniques    2014, 37 (08): 80101-080101.   DOI: 10.11889/j.0253-3219.2014.hjs.37.080101
Abstract339)      PDF(pc) (1225KB)(2926)       Save
Background: Synchrotron radiation micro probe analysis technique has been improved rapidly in recent years. Accurate qualitative or quantitative information on the interest element in environmental and biological samples such as atmospheric particles, soil, plant and earthworm plays a crucial role in the understanding of the effect of these elements in the samples. However, determination of these samples with complex matrices is a difficulty in multiple disciplines. With the rapid development of this area, the synchrotron-based techniques have been introduced to this area and have been widely used in analyzing various complex samples due to its superiority in fast and non-destructive determination. Purpose: In this review, the synchrotron source and its advantages in investigation on elemental analysis of the complex natural samples are introduced. Then, the applications of Synchrotron micro-X-ray fluorescence (μ-SXRF) and Synchrotron X-ray absorption fine spectroscopy (XAFS) in atmospheric particles, soil, plant and earthworm are reviewed, covering the distribution and the speciation of elements in these samples. Methods: μ-SXRF permits in situ mapping of biologically important elements of the sample even at sub-micrometer scale so that the spatially resolved element distribution maps can be obtained. XAFS allows determination of the speciation of high heterogeneity samples by providing the element oxidation state and local coordination environment. Results and Conclusion: μ-SXRF and XAFS have been widely used in element distribution and speciation of nature samples, especially for micro scale samples or micro area of samples such as atmospheric particles, soil, plant and earthworm. It is relevant to study thoroughly the presence, source, mobilization and fate of the elements using the information. Some challenges and future perspectives of the research and the tendency of development of synchrotron radiation technology have also been suggested.
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Design of high voltage power supply of miniature X-ray tube based on resonant Royer
LIU Xiyao, ZENG Guoqiang, TAN Chengjun, LUO Qun, GONG Chunhui, HUANG Rui
Nuclear Techniques    2013, 36 (8): 80403-080403.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.080403
Abstract495)      PDF(pc) (1714KB)(2734)       Save

Background: In recent years, X rays are widely used in various fields. With the rapid development of national economy, the demand of high quality, high reliability, and high stability miniature X-ray tube has grown rapidly. As an important core component of miniature X-ray tube, high voltage power supply has attracted wide attention. Purpose: To match miniature, the high voltage power supply should be small, lightweight, good quality, etc. Based on the basic performance requirements of existing micro-X-ray tube high voltage power supply, this paper designs an output from 0 to ?30 kV adjustable miniature X-ray tube voltage DC power supply. Compared to half-bridge and full-bridge switching-mode power supply, its driving circuit is simple. With working on the linear condition, it has no switching noise. Methods: The main circuit makes use of DC power supply to provide the energy. The resonant Royer circuit supplies sine wave which drives to the high frequency transformer’s primary winding with resultant sine-like high voltage appearing across the secondary winding. Then, the voltage doubling rectifying circuit would achieve further boost. In the regulator circuit, a feedback control resonant transistor base current is adopted. In order to insulate air, a silicone rubber is used for high pressure part packaging, and the output voltage is measured by the dividing voltage below ?5 kV. Results: The stability of circuit is better than 0.2%/6 h and the percent of the output ripple voltage is less than 0.3%. Keeping the output voltage constant, the output current can reach 57 ?A by changing the size of load resistor. This high voltage power supply based on resonant Royer can meet the requirement of miniature X-ray tube. Conclusions: The circuit can satisfy low noise, low ripple, low power and high voltage regulator power supply design. However, its efficiency is not high enough because of the linear condition. In the next design, to further reduce power consumption, we could improve the efficiency by controlling the current of resonant circuit.

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Pulse shape discrimination and energy calibration of EJ301 liquid scintillation detector
CHANG Le, LIU Yingdu, DU Long, WANG Yuting, CAO Xiguang, ZHANG Guoqiang, WANG Hongwei, MA Chunwang, ZHANG Song, ZHONG Chen, LI Chen
Nuclear Techniques    2015, 38 (2): 20501-020501.   DOI: 10.11889/j.0253-3219.2015.hjs.38.020501
Abstract1023)      PDF(pc) (1146KB)(2730)       Save
Background: EJ301 liquid scintillation detector has good time characteristics, pulse shape discrimination ability and the neutron detection efficiency. Purpose: This study aims to achieve the energy calibration, the pulse shape discrimination (PSD) ability etc. of EJ301 organic liquid scintillation detector. Methods: The waveform digital sampler DT5720 and digital pulse processing-pulse shape discrimination (DPP-PSD) control software were employed to simplify the data acquisition system. The pulse shape discrimination parameters such as the widths of long and short gates could be set up by software. The Compton peaks of 241Am (0.0595MeV), 137Cs-60Co (0.662 MeV, 1.171MeV, 0.662 MeV) and 40K (1.461 MeV) sources were used to obtain experimental data for pulse shape discrimination and the energy calibration of EJ301. Results: Experimental results show EJ301 detector has high efficiency, strong neutron/gamma-PSD ability. Conclusion: DT5720 and DPP-PSD control software have powerful function and are easy to use for both the PSD and energy calibration of EJ301. EJ301 organic liquid scintillation detector can be used for neutron measurement, and is suitable for measuring fast neutron energy spectrum and time of flight.
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Cited: Baidu(6)
A method of communication between EPICS IOC and EtherCAT devices
HE Yongcheng, WANG Chunhong, WU Xuan
Nuclear Techniques    2014, 37 (11): 110102-110102.   DOI: 10.11889/j.0253-3219.2014.hjs.37.110102
Abstract638)      PDF(pc) (913KB)(2632)       Save
Background: EtherCAT (Ethernet Control Automation Technology) is a kind of real-time Ethernet fieldbus protocol for industrial automation. The control system of many large-scale scientific facilities such as Beijing electron-positron collider (BEPCII), Chinese spallation neutron source (CSNS) was designed based on EPICS (Experimental Physics and Industrial Control System). Purpose: The aim is to implement EtherCAT as a real-time high speed control system solution for the EPICS based control system. Methods: The communication between EPICS IOC (Input/Output Controller) and EtherCAT devices was realized by using the OPC (Object Linking and Embedding for Process Control) Gateway driver. A real-time temperature monitoring appliance was taken as testing example. Results: The test results show that the communication between EPICS IOC and EtherCAT devices using the OPC Gateway driver is efficiently implemented. Conclusion: EtherCAT devices can be applied to communicate with the EPICS IOC to achieve real-time high-speed control by using the OPC Gateway driver.
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Cited: Baidu(1)
Physics design of a compact medical cyclotron
HE Xiaozhong, YANG Guojun, LONG Jidong, PANG Jian, ZHANG Kaizhi, SHI Jinshui
Nuclear Techniques    2014, 37 (01): 10201-010201.   DOI: 10.11889/j.0253-3219.2014.hjs.37.010201
Abstract418)      PDF(pc) (1105KB)(2620)       Save

Background: A compact cyclotron with energy of 11 MeV and current of 50 ?A is under construction in Institute of Fluid Physics of China Academy of Engineering Physics. The compact cyclotron is developed for medical isotope production. Purpose: To minimize the cost and to shorten the time of the development of the compact cyclotron, a lot of efforts were dedicated to the physics design of the compact cyclotron. Methods: Physics design of the main magnet was performed using TOSCA software, and start-to-end beam dynamics design was performed using home-made software CYCDYN. Results: Physics design of the compact cyclotron was given in details. Design methods and results of the main subsystems (including ion source, radial sector focusing magnet, RF cavity, central region and extraction system) were also given in this paper. Conclusion: Now commissioning of this cyclotron has been finished, and the goal for extracting proton beams of 11 MeV and 50 uA on average has been achieved. Physics design of the cyclotron has been validated by the commissioning results.

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Cited: Baidu(3)
Monte Carlo calculation of dose point kernel and absorbed dose distribution for electrons and photons
CHEN Shaowen, HUANG Long, WU Muying, TANG Qiang, LIU Xiaowei, ZHANG Chunxiang
Nuclear Techniques    2013, 36 (7): 70205-070205.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.070205
Abstract402)      PDF(pc) (1953KB)(2419)       Save

Background: The dose point kernel and the absorbed fraction are essential in the absorbed dose calculation for radionuclide therapy. Purpose: To calculate the scaled dose point kernels for 1MeV monoenergetic electrons and 32P, 90Y , 131I radionuclides, the absorbed fractions for 0.2 MeV and 4 MeV monoenergetic electrons and 32P, 90Y radionuclides which uniformly distributed in water spheres of various mass ranging from 10?2 to 103 g, and the radial distributions of absorbed dose rates for 32P, 131I, 90Y nuclides and 15 keV, 30 keV, 100 keV photons which uniformly distributed in a water (tumor) spherical shell (0.22?r?0.66cm) with an activity of 1MBq/cm3. Methods: EGSnrc Monte Carlo programs were used for simulation. Results: The calculation results were compared with those of other works. Conclusions: The results could give some help to absorbed dose calculations for radionuclide therapy.

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Cited: Baidu(1)
Design of nuclear imaging system based on MURA coded aperture collimator
CHEN Lihong, LI Yongping, ZHAO Cuilan, YUAN Chao
Nuclear Techniques    2013, 36 (8): 80402-080402.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.080402
Abstract412)      PDF(pc) (1691KB)(2395)       Save

Background: Location nuclear imaging systems have been used in many fields, such as astronomical observation, radioactive source monitoring, nuclear development, biomedicine, etc. Purpose: It puts forward much higher requirements of monitoring and control of safety of nuclear facilities and radioactive sources. In this paper, a new portable nuclear imaging system is designed, which can be used in far field imaging. Methods: It uses high resolution detector which consists of LaBr3 crystal and H8500 position sensitive photomultiplier to meet the design requirements of high resolution. In order to acquire the higher radiation collection efficiency, we choose modified uniformly redundant arrays (MURA) as system collimator. It uses the maximum likelihood-expectation maximization (MLEM) algorithms in reconstruction procedure. Results: The test results show that the imaging system can image the far field radioactive source clearly. The field-of-view of our system can achieve the design goal: ±10°?±20°, and its resolution can be variable among 0.923°?2.038°. Conclusions: It can meet the design requirements of resolution and FOV very well. This radiation imaging system can achieve miniaturization and portability radiation imaging robot which is suited for the long-range control.

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Cited: Baidu(2)
GEANT4 simulation and imaging reconstruction by backprojection algorithm for Compton camera
DING Changji, MAO Benjiang, YUAN Yonggang, JIANG Zhigang, YANG Chaowen
Nuclear Techniques    2015, 38 (11): 110402-110402.   DOI: 10.11889/j.0253-3219.2015.hjs.38.110402
Abstract880)      PDF(pc) (2109KB)(2394)       Save
Background: Due to its imaging principle advantages and the development of detectors, nuclear electronics, Compton camera has once again put forward. Purpose: This study aims to build a Compton camera via Monte Carlo simulation and test its backprojection algorithm. Methods: By using Monte Carlo simulation software GEANT4, a Compton camera with stripes structure is designed and data for reconstruction image of source is read out. Backprojection imaging reconstruction algorithm is studied for getting the reconstruction of source. Results: Using backprojection algorithm and simulated Compton camera, when the distance between source and the scattering detector is 40 mm, the spatial resolution is FWHM=8.0 mm, angular resolution is 3° and γ photon imaging efficiency is 0.38%, which are better than most of the pinhole and coded aperture γ camera imaging. Conclusion: Because of the existence of large amount of data, Compton camera needs long calculation time for measuring data. The next step is improving simulated Compton camera to study its performance parameters, while the maximum likelihood algorithm could improve the spatial resolution of Compton camera.
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Cited: Baidu(1)
Calculation and analysis of radioactive source term in PWR assemblies
CHEN Haiying, QIAO Yahua, WANG Shaowei, CHEN Yan, LAN Bing, ZHANG Chunming
Nuclear Techniques    2014, 37 (04): 40601-040601.   DOI: 10.11889/j.0253-3219.2014.hjs.37.040601
Abstract479)      PDF(pc) (473KB)(2392)       Save

Background: When fission occurs in fuel of reactor core, it produces a large amount of radioactive materials, which may cause harm to the environment and human health. Purpose: The radioactive materials in fuel could provide input data for shielding design of reactor coolant radioactive source term, analysis of accident source term and radioactive consequence assessment. Methods: The calculation of radioactive source in fuel was studied for pressurized water reactor, the calculation methods and models were established using ORIGEN-S, and the difference of nuclides radioactivity under different burnup was also studied. The effect of different versions of ENDF/B cross-section database on the calculation results was analyzed, so as to provide a basis for the calculation of radioactive source in fuel. Results: The results showed that the method established by ORIGEN-ARP was more suitable for calculating radioactive source term in fuel assemblies and the different versions of ENDF/B database had a great impact on radioactivity calculation. Conclusion: Based on the ENDF/B-VII database, using ORIGEN-ARP to calculate radioactive source term in fuel assemblies could not only improve efficiency, but also improve the calculation accuracy.

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Cited: Baidu(1)
P3HT/PCBM polymer thin films studied by synchrotron-based grazing incidence X-ray diffraction
YANG Yingguo, ZHENGGUAN Haojie, JI Gengwu, FENG Shanglei, LI Xiaolong, GAO Xingyu
Nuclear Techniques    2014, 37 (02): 20101-020101.   DOI: 10.11889/j.0253-3219.2014.hjs.37.020101
Abstract536)      PDF(pc) (1612KB)(2359)       Save

Background: The microstructures of P3HT (poly(3-hexyl-thiophene)) in P3HT/PCBM ([6,6]-phenyl C61-butyric acid methyl ester) thin films play a key role in governing the performance of organic solar cells (OSCs) based on these films. Purpose: We aim to study the self-organization of P3HT in the P3HT/PCBM thin films annealed at different temperatures. Methods: Using different incidence angles, information about the microstructures of P3HT at different depths in these films was obtained by synchrotron based grazing incidence X-ray diffraction (GIXRD). Results: It is shown that the crystalline structure of P3HT has been substantially improved by thermal annealing. One dimensional GIXRD clearly indicates that P3HT edge-on structures in the inner layers have been improved with their number increased in comparison with those at the surface and the interface layers. In addition, thermal annealing also helps the formation of P3HT face-on structures in the films, as evidenced by 2 dimensional GIXRD. Conclusion: The improved structures in these films lead to more charge transport channels formed to improve the carrier mobility, which in turn helps the improvement of OSCs. Thus, the present GIXRD results will improve the understanding of annealing effects at different depths of the P3HT/PCBM thin films for enhanced OSCs devices.

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Research on 1.6-GeV proton translation process using Geant4
YAO Zhiming, SONG Guzhou, HEI Dongwei, MA Jiming, ZHOU Ming, DUAN Baojun, SONG Yan, HAN Changcai
Nuclear Techniques    2014, 37 (03): 30205-030205.   DOI: 10.11889/j.0253-3219.2014.hjs.37.030205
Abstract447)      PDF(pc) (732KB)(2353)       Save

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.

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Application progress of solid 29Si, 27Al NMR in the research of cement-based materials
FENG Chunhua, WANG Xijian, LI Dongxu
Nuclear Techniques    2014, 37 (01): 10502-010502.   DOI: 10.11889/j.0253-3219.2014.hjs.37.010502
Abstract282)      PDF(pc) (273KB)(2337)       Save

Background: The solid-state Nuclear Magnetic Resonance (NMR) is an effective method for the research of cement-based materials. Now it focuses on using solid 29Si and 27Al NMR to research the hydration structure of the cement-based materials in cement chemistry. Purpose: A theoretical guidance is proposed for solid 29Si and 27Al NMR technology used in cement chemistry research. Methods: We reviewed the application of solid 29Si and 27Al NMR in the cement-based materials and analyzed the problem among the researches. Results: This paper introduced an fundamental, relevant-conditions and basic parameters of NMR, and studied the technical parameters of solid 29Si and 27Al NMR together with the relationship among the hydration structure of cement-based material. Moreover, this paper reviewed the related domestic and overseas achievements in the research of hydration structure of the cement-based materials using solid 29Si and 27Al NMR. Conclusion: There were some problems in the research on cement-based materials by technology of solid 29Si and 27Al NMR. NMR will promote the Hydration theory of cement-based material greatly.

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Cited: Baidu(2)
Measurement and study of the photocathode quantum efficiency of photoelectric conversion device
XIA Jingkai, QIAN Sen, WANG Wenwen, NING Zhe, CHENG Yaping, WANG Yifang, JIANG Xiaoshan, WANG Zheng, LI Xiaonan, QI Ming, HENG Yuekun, LIU Shulin
Nuclear Techniques    2014, 37 (09): 90401-090401.   DOI: 10.11889/j.0253-3219.2014.hjs.37.090401
Abstract509)      PDF(pc) (784KB)(2314)       Save
Background: Photoelectric devices such as photomultiplier tubes (PMTs), photo diodes (PDs) and solar cells are widely used in many applications, so reliable evaluation on the performances of such devices is quite necessary, especially for the accurate measurements and calibrations on the photocathode quantum efficiency (QE). Purpose: We aim to build up a cathode performance evaluation system and study the properties of different types of cathodes. Methods: Two different methods named as the relative measurement and the direct measurements were employed to measure the QE values of cathodes. In addition, a 2D platform was built to achieve convenient and accurate processes for the plane type photocathode position uniformity test. Results: With the evaluation system, the cathode properties of dozens of photoelectric devices were tested. The measured QE results, either from the relative or the direct measurement, are consistent with the data provided by the manufacturers or a third party. Conclusion: Our cathode evaluation system is reliable and could be used to study the detailed photocathode properties such as QE, spectral response and position uniformity.
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Cited: Baidu(1)
Real-time signal transmission performance tests with optical fiber based on Aurora protocol
LU Ruiqi, ZENG Jianping, ZHAO Yubin, REN Hailong
Nuclear Techniques    2015, 38 (3): 30404-030404.   DOI: 10.11889/j.0253-3219.2015.hjs.38.030404
Abstract459)      PDF(pc) (569KB)(2300)       Save
Background: General Purpose Powder Diffractometer (GPPD) is one of Chinese Spallation Neutron Source (CSNS) diffractometers, which adopts Symptom Scale of Neurotransmitter Deficiency (SSND) detecting the position and the flight time of neutron when it hits, and the electronics system processes the detected neutron information. The shooting time T0, as a time reference point of the electronics system, is a real time signal. Traditional cable transmission meets the real-time signal transmission requirements, however, laying work will be rather complex and bring great difficulties to project since numerous of cable was needed. Purpose: The electronics control circuits is needed to transfer the received signal T0 to the lower electronics in real time with low propagation delay and low jitter via optical fiber, and the the propagation delay is less than 1 μs which including the 15-m optical fiber delay, the jitter is less than 0.1 μs. Methods: This paper describes a transferring scheme based on Spartan6 XC6SLX75T FPGA using Aurora protocol via optical fiber. The testing program is based on ISE Design Suite14.4 FPGA development platform, adopting high-precision oscilloscopes to the measure and calculate the transmission delay and jitter of different rise time signal T0 repeatly. Results: Repeated measurements show that the maximum propagation delay is less than 600ns and that the maximum jitter is less than 4 ns, in addition, the stability of jitter stability is good, and it meets the system requirements. Conclusion: It is feasible to use Aurora protocol via optical fiber to transfer real-time signal T0. Signal rise time has a certain influence on the delay and jitter, longer signal rise time corresponds longer delay and greater the jitter, so to shorten rise time of signal can reduce the transmission delay and jitter.
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Research of accelerator-based neutron source for boron neutron capture therapy
LI Changkai, MA Yingjie, TANG Xiaobin, XIE Qin, GENG Changran, CHEN Da
Nuclear Techniques    2013, 36 (9): 90203-090203.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.090203
Abstract422)      PDF(pc) (2256KB)(2281)       Save

Background: 7Li(p,n) reaction of high neutron yield and low threshold energy has become one of the most important neutron generating reactions for Accelerator-based Boron Neutron Capture Therapy(BNCT). Purpose: Focuses on neutron yield and spectrum characteristics of this kind of neutron generating reaction which serves as an accelerator-based neutron source and moderates the high energy neutron beams to meet BNCT requirements. Methods: The yield and energy spectrum of neutrons generated by accelerator-based 7Li(p,n) reaction with incident proton energy from 1.9 MeV to 3.0 MeV are researched using the Monte Carlo code-MCNPX2.5.0. And the energy and angular distribution of differential neutron yield by 2.5-MeV incident proton are also given in this part. In the following part, the character of epithermal neutron beam generated by 2.5-MeV incident protons is moderated by a new-designed moderator. Results: Energy spectra of neutrons generated by accelerator-based 7Li(p,n) reaction with incident proton energy from 1.9 MeV to 3.0 MeV are got through the simulation and calculation. The best moderator thickness is got through comparison. Conclusions: Neutron beam produced by accelerator-based 7Li(p,n) reaction, with the bombarding beam of 10 mA and the energy of 2.5 MeV, can meet the requirement of BNCT well after being moderated.

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Research on the key technology of high-power solid-state pulse modulator
LI Feng, CHEN Zhihao, WU Yonghua
Nuclear Techniques    2013, 36 (7): 70104-070104.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.070104
Abstract423)      PDF(pc) (1674KB)(2227)       Save

Background: For construction of free-electron laser (FEL) apparatus, we designed a high-power solid-state modulator system based on the module of insulated gate bipolar transistor (IGBT) switch. Purpose: To meet the higher performance requirements of linear accelerator microwave power source for the FEL. Methods: The module circuit of the high-power modulator is introduced, as well as the critical auxiliary circuit including protection circuit of IGBT, damping circuit, demagnetization circuit and compensating circuits. Results: The whole modulator system is simulated by using software and the module differences that may occurred. The modulator with inductive adder topology can generate a 130 kV, 100A and 13MW pulse power. Conclusions: The results show that the inductive adder pulse modulator technology is feasible.

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Software management in EPICS environment
LEI Lei, HAN Lifeng, XU Haixia, LI Yongping
Nuclear Techniques    2015, 38 (6): 60501-060501.   DOI: 10.11889/j.0253-3219.2015.hjs.38.060501
Abstract449)      PDF(pc) (579KB)(2221)       Save
Background: Compared with commercial SCADA (Supervisory Control and Data Acquisition) software, EPICS (Experimental Physics and Industrial Control System) control system has no uniform way for software management at present. Developers in different projects deploy and invoke EPICS software modules in different ways. However, it is particularly important to manage the software modules scientifically and normatively for projects like thermonuclear fusion reactor, proton therapy and Thorium Molten Salt Reactor (TMSR), which helps to improve the reliability, maintainability and usability of system. Purpose: We aim to deploy EPICS software modules automatically and call them normatively. Methods: We implement the directory management using Linux Filesystem Hierarchy Standard (FHS), deploy software modules with Red Hat Package Manager (RPM) and shell scripts and manage all software modules with Linux service. Results: The scheme runs very well and reduces manual operation greatly. Conclusion: The results indicate that this scheme can address some issues in the usage of EPICS, which may help to build a unified, fully automated software platform for TMSR I&C system.
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CFD simulation analysis and validation for CPR1000 pressurized water reactor
ZHANG Mingqian, RAN Xiaobing, LIU Yanwu, YU Xiaolei, ZHU Mingli
Nuclear Techniques    2013, 36 (10): 100601-100601.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.100601
Abstract237)      PDF(pc) (5349KB)(2191)       Save

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.

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A numerical method for extracting dual-energy value of X-ray transmission image based on MCNP
XIANG An, CHEN Ruitao
Nuclear Techniques    2014, 37 (07): 70203-070203.   DOI: 10.11889/j.0253-3219.2014.hjs.37.070203
Abstract306)      PDF(pc) (1384KB)(2188)       Save
Background: Traditional dual-energy X-ray inspection technology serves to classify different materials based on the proper value related with effective atomic number. Purpose: This paper aims to solve the problem of the relevance between the proper value and material’s thickness (thickness effect), which reduces the reliability of dual-energy inspection technology. Methods: A numerical method which combines Simpson formula and sequential quadratic programming (SQP) method is proposed to eliminate the thickness effect of dual-energy values. The process of X-ray inspection is simulated by Monte Carlo method based on MCNP. Probability-classification method is used to evaluate the effectiveness of diminishing error probability of material-classification, and classification boundaries of different materials. A practical X-ray inspection machine is used to verify this method. Results: The experimental results indicate that not only the thickness effect is diminished obviously by this method, but also the classification boundaries are effectively achieved. Conclusion: The dual-energy value of X-ray transmission image can be extracted by our proposed method with effectiveness and practical applicability.
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Measurement of γ absorption dose rate through measuring the full energy peak of γ spectrum
HE Jun, YANG Chaowen
Nuclear Techniques    2014, 37 (07): 70403-070403.   DOI: 10.11889/j.0253-3219.2014.hjs.37.070403
Abstract535)      PDF(pc) (704KB)(2170)       Save
Background: At present most radiation dose meters have the serious problem of energy response, and they just use the count rate plus relative correction method to measure the dose rate. This method has large error, and cannot distinguish the type of radionuclide, also cannot obtain the contribution of each radionuclide to the dose rate. Purpose: The research of new method is to measure the dose rate and improve the accuracy of measurement. Methods: The method of γ dose rate measurement through measuring full energy peak of γ spectrum was put forward, the angular response function of parallel γ ray injected into detector was defined. The average angular response over full space in the energy range from 0.02 MeV to 3 MeV was calculated by Monte Carlo simulation for ?50mm×50mm NaI(Tl) detector. Measurement tests have been done using standard radioactive sources of 137Cs, 60Co, 152Eu, 133Ba and in reference radioactive field of 137Cs, 60Co, 226Ra, 241Am in a national lab. Results: The test errors are smaller than 2% compared with the theoretical value for standard sources, and smaller than 3% compared with the value of PTW 10 L spherical chamber for reference radiation field. Conclusion: The results show that the method is suitable for the dose rate measurement for a wide range of energy without experimental calibration, can calculate the dose rate of different energy ray, and at the same time identify the radioactive nuclides in the radiation source.
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Cited: Baidu(1)
Detection efficiency simulation and measurement of 6LiI/natLiI scintillation detector
DU Long, CHANG Le, WANG Yuting, ZHANG Song, CAO Xiguang, WANG Hongwei, ZHANG Guoqiang, ZHONG Chen, LI Chen
Nuclear Techniques    2014, 37 (04): 40201-040201.   DOI: 10.11889/j.0253-3219.2014.hjs.37.040201
Abstract450)      PDF(pc) (658KB)(2160)       Save

Background: Being of very high detection efficiency and small size, Lithium iodide (LiI) scintillator detector is used extensively in neutron measurement and environmental monitoring. Purpose: Using thermal reactor, neutron detectors will be tested and calibrated. And a new neutron detector device will be designed and studied. Methods: The relationship between the size and detection efficiency of the thermal neutron detector 6LiI/natLiI was studied using Monte Carlo code GEANT4 and MCNP5 package, and the thermal neutron efficiency of detector was calibrated by reactor neutrons. Results: The theoretical simulation shows that the thermal neutron detection efficiency of detector of 10-mm thickness is relatively high, the enriched 6LiI is up to 98% and the nature natLiI 65%. The thermal neutron efficiency of detector is calibrated by reactor thermal neutrons. Considering the neutron scattering by the lead brick, high density polythene and environment neutron contribution, the detection efficiency of 6LiI detector is about 90% and natLiI detector 70%. Conclusion: The detector efficiency can reach the efficiency value of theoretical calculations.

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Cited: Baidu(6)
MCNP coupled with post-processing software application development
HE Zehong, YE Minyou, WANG Zhongwei, MAO Shifeng, XU Kun
Nuclear Techniques    2015, 38 (6): 60601-060601.   DOI: 10.11889/j.0253-3219.2015.hjs.38.060601
Abstract740)      PDF(pc) (911KB)(2141)       Save
Background: Neutron flux and thermal distributed computing are vital parts of the process of nuclear fusion reactor design, its representative calculation software MCNP is based on the Monte Carlo method. However, the output of MCNP is a text file, thus the results are not conveniently and visually represented by manual analysis, and cannot be directly imported into post-processing software such as Ensight, Paraview and ANSYS for processing. Purpose: In order to enhance the efficiency of data analysis of MCNP output, a coupling program between the MCNP and post-processing software is proposed and implemented in this paper. Methods: The Microsoft Visual Studio 2010 (VS2010) is taken as a development platform, the coupling program is developed using C/C++ programming language to perform numerical/logic operations and various kinds of data format conversion required by post-processing software such as Ensight, Paraview and ANSYS, etc. Results: The coupling program was tested via “while-box” method, logical operations of MCNP calculation results, and data format conversion of MCNP data file processed by this program are satisfied for the requirement of the post-processing software for visual analysis. Conclusion: It provides effective support tools that bridge the connection between MCNP and the post-processing software for practical engineering design.
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Optimizing design for the maze exit of a 10-MeV electron irradiation accelerator
DUAN Zongjin, CHEN Yukai, REN Guangyi, HE Lijuan, LI Yuxiong, CHEN Zhi
Nuclear Techniques    2013, 36 (11): 110203-110203.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.110203
Abstract239)      PDF(pc) (3938KB)(2122)       Save

Background: Irradiation accelerator is being used more and more widely, but the optimizing of radiation shielding is always a problem to be solved. Purpose: To make the dose rates of the maze exit lower and the cost to achieve it less, it is of great significance to design a shielding which is cheap and effective. Methods: The radiation dose rates at different maze exits of a 10-MeV industrial electron linear accelerator were compared by formula and Monte Carlo (Fluka) method. A real-time measurement system composed of Mini Digital Data Logging (Mini-DDL) and Gamma detectors was also used. Results: With one corner added to the exit, another scattering would be generated. The dose rate of exit before changing was 3?4?Gy?h?1 while it was 200nGy?h?1 after that. Conclusion: The radiation dose rate at the exit will be reduced by one order of magnitude because of another scattering generated by the added turn to the maze exit. All of these do not increase any additional cost and conform to the ALARA (as low as reasonably achievable) principle. It provides a good reference for the future design of shielding for industrial electron linear accelerator.

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Cited: Baidu(3)
Preparation of FLiNaK molten salt
ZONG Guoqiang, CHEN Bo, ZHANG Long, SUN Jiahong, DONG Qun’an, CHEN Wei, XIAO Jichang
Nuclear Techniques    2014, 37 (05): 50604-050604.   DOI: 10.11889/j.0253-3219.2014.hjs.37.050604
Abstract785)      PDF(pc) (716KB)(2100)       Save

Background: Possessing a series of advantages, such as low neutron absorption cross section, much lower vapor pressure and good heat transfer performance fluoride molten salts are widely used in the high-temperature hydrogen, solar storage, nuclear fuel and other energy fields. Among them, ternary mixture of LiF-NaF-KF (FLiNaK) is one of the most common candidate molten salt systems. Purpose: We aim to examine the effect of temperature, time, crucible material and fluoride reagents on the quality of the molten salt, and preliminarily master key process parameters for preparation of FLiNaK molten salt. Methods: The formation of FLiNaK molten salt was studied by a vacuum melting platform. The optional preparation conditions were obtained through the screening of melting temperature, timing, crucible material and fluorination reagent. Results: In the presence of NH4HF2, the oxygen content in FLiNaK salt could be controlled below 2×10?4. Metal ion impurities in molten salt, according to the general requirements of the quality standard for molten salt reactor, of which Be, Cu, Fe, Zr and Cd contents are less than 5×10?6. And impurities of sulfate and phosphate anions are less than 1×10?4 and 3×10?5, respectively. Conclusion: Using the present preparation method, the corrosion of furnace was greatly reduced. It was an efficient, low-cost, and safe process for the preparation of FLiNaK molten salt.

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Cited: Baidu(7)
High temperature gas-cooled pebble bed reactor steady state thermal-hydraulics analyses based on CFD method
SONG Shixiong, WEI Quan, CAI Xiangzhou, GUO Wei
Nuclear Techniques    2013, 36 (12): 120601-120601.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.120601
Abstract614)      PDF(pc) (4976KB)(2084)       Save

Background: Based on general purpose CFD code Fluent, the PBMR-400 full load nominal condition thermal-hydraulics performance was studied by applying local thermal non-equilibrium porous media model. Purpose: In thermal hydraulics study of the gas cooled pebble bed reactor, the core of the reactor can be treated as macroscopic porous media with strong inner heat source, and the original Fluent code can not handle it properly. Methods: By introducing a UDS in the calculation domain of the reactor core and subjoining a new resistance term, we develop a non-equilibrium porous media model which can give an accurate description of the core of the pebble bed. The mesh of CFD code is finer than that of the traditional pebble bed reactor thermal hydraulics analysis code such as THERMIX and TINTE, thus more information about coolant velocity fields, temperature field and solid phase temperature field can be acquired. Results: The nominal condition calculation results of the CFD code are compared to those of the well-established thermal-hydraulic code THERMIX and TINTE, and show a good consistency. Conclusion: The extended local thermal non-equilibrium model can be used to analyse thermal-hydraulics of high temperature pebble bed type reactor.

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PWR core transient temperature numerical simulation based on porous media model
CHEN Sen, LIU Yu, TIAN Maolin, TIAN Wenxi, QIU Suizheng, SU Guanghui
Nuclear Techniques    2015, 38 (9): 90601-090601.   DOI: 10.11889/j.0253-3219.2015.hjs.38.090601
Abstract343)      PDF(pc) (1552KB)(2083)       Save

Background: The coolant flow and heat transfer in the reactor are significant to the safety of pressure water reactor (PWR). Purpose: This study aims to obtain the coolant flow and heat transfer characteristics in the reactor core. Methods: The complete model of pressure vessel is built by Pro/E, and the thermal hydraulic characteristics of the core are simulated with commercial software CFX by using the porous medium model in the core. Results: The simulation results show that the application of porous media model can display the core coolant temperature distribution effectively and correctly, and the asymmetric operation conditions can cause asymmetric on reactor core. The transient accident calculation results show that the highest temperature of the coolant appears in the upper of the core. Conclusion: The porous media model can be used in the reactor core and it has a certain reference value for the thermal-hydraulic safety of pressurized water reactor.

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Three-dimensional visualization of fibrochondrocytes in rabbit patella-patellar tendon junction using synchrotron radiation-based X-ray phase contrast tomography
CHEN Huabin, HU Jianzhong, ZHOU Jingyong, ZHENG Cheng, WANG Zhanwen, CHEN Can, CAO Yong, YIN Xianzhen, LYU Hongbin
Nuclear Techniques    2015, 38 (11): 110101-110101.   DOI: 10.11889/j.0253-3219.2015.hjs.38.110101
Abstract332)      PDF(pc) (3229KB)(2054)       Save

Background: Synchrotron radiation-based X-ray phase-contrast computed tomography (SR-XPCT) is an advanced tool for nondestructive analysis of three dimensional inner microstructure of samples, and plays an important part in the researches such as spinal cord microvasculature and lung bronchium. Purpose: This study was to investigate the three-dimensional morphology of fibrochondrocytes in rabbit patella-patellar tendon junction (PPTJ) using SR-XPCT, and develop an advanced imaging method. Methods: Three PPTJs were harvested from healthy mature female New Zealand rabbits. The specimens were scanned by SR-XPCT at BL13W1 of Shanghai Synchrotron Radiation Facility (SSRF) in China. The tomographic image was captured by Charge Coupled Device (CCD) detector with a 0.65-μm resolution. The three-dimensional visualization images of PPTJ were reconstructed by VG Studio Max. After that, the specimens were embedded by paraffin for Safranin O/Fast-green staining. Results: High-resolution three-dimensional visualization images of PPTJ and the parameters of the chondrocytes in fibrocartilage zone were successfully obtained via the SR-XPCT. With spherical and ellipsoidal morphologic features and its configuration characteristics in three dimension, the fibrochondrocytes revealed by SR-XPCT were consistent with the results of traditional histological staining. The parameters of chondrocytes showed that the mean diameter of chondrocyte was (10.139±1.265) μm, the mean volume was (291.187±87.283) μm3 and 75.4% of the chondrocytes’ volume ranged from 200 μm3 to 400 μm3, the mean sphericity degree was 0.711±0.079, and 84.9% of chondrocytes’ sphericity degree ranged from 0.605 to 0.805. Conclusion: The three-dimensional microstructure of the PPTJ was intuitively, accurately and undistortedly realized by the SR-XPCT, which may act as a novel instrument to access the three-dimensional microstructure changes during the PPTJ healing process.

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Comparative analysis and measurement of focus spot for X-ray source
SUN Chaoming, TANG Guangping, LI Qiang, WANG Zengyong
Nuclear Techniques    2015, 38 (11): 110202-110202.   DOI: 10.11889/j.0253-3219.2015.hjs.38.110202
Abstract414)      PDF(pc) (5036KB)(2051)       Save
Background: Image quality in radiographic testing is often conditioned by the size and distribution of X-ray source. However, determination of focal spot is not performed effectively in practice, thus it is difficult to accurately control the image quality in the testing. Purpose: This study aims to obtain a quick and efficient test method to evaluate the focal spot for X-ray source. Methods: Test tools such as pinhole plate, star test pattern and duplex wire image quality indicator (IQI) were used to measure the focal spot of a portable X-ray source separately. Several measurements were carried out and compared in details. Results: Results of star test pattern and duplex wire IQI were coincident, but different from the results of pinhole imaging method obviously. Conclusion: Nominal focal spot size of an X-ray source may be considerably different from that in practice use, so it is necessary to timely evaluate characteristics of the focal spot. The duplex wire IQI can usually replace star test pattern to measure un-sharpness in radiographic testing images and to evaluate focal spot size.
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Method of digital Dither adding for digital multi-channel pulse amplitude analyzer
CHEN Xiaomeng, ZHANG Yuzhong, AI Xianyun, LIANG Weiping, XIAO Wuyun
Nuclear Techniques    2015, 38 (5): 50401-050401.   DOI: 10.11889/j.0253-3219.2015.hjs.38.050401
Abstract412)      PDF(pc) (2008KB)(2013)       Save
Background: The key technology of digital multi-channel pulse amplitude analyzer (DMCA) has been surmounted in China, however, with the increasing of the translation gain increases of DMCA, one of the difficulties is how to make the nonlinear performance index of the system reach the standard. Technology of Dither has been used to realize “Bit Gain” in overseas research while it is still a deficiency in DMCA study in China. Purpose: This study aims to study the application of Dither technology in DMCA and discuss relevant digital Dither technology for DMCA. Method: Based on DMCA architecture characteristics, Dither signal is produced and removed in field programmable gate array (FPGA) by linear feedback shift register (LFSR), and is added to DMCA by the circuit of base line. Energy resolution and differential nonlinearity (DNL) of DMCA system has been measured to study the effect of Dither on DMCA. The mechanism of how the Dither affects DMCA has been analyzed. Results: Experimental tests showed that DNL of DMCA is improved by adding Dither while keep the same the energy resolution, verifying the applicability of this method. Conclusion: The technology method of digital Dither adding for DMCA is of practical significance to the further research to improve the precision of DMCA.
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Cited: Baidu(6)
Impact of dust storm on chemical species of S, Cl and Ca in Shanghai atmosphere particles
LONG Shilei, LIU Ke, ZENG Jianrong, CAO Lingling, BAO Liangman, LIN Jun, LI Yan, MA Chenyan
Nuclear Techniques    2013, 36 (10): 100101-100101.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.100101
Abstract216)      PDF(pc) (2372KB)(2011)       Save

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 CaCO3 and 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.

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Radio-synthesis and application research advance of amino acid molecular tracers labeling with 18F and 11C for tumor PET imaging
HE Shanzhen, WANG Shuxia, WANG Peng, LI Shilei, TANG Ganghua
Nuclear Techniques    2014, 37 (08): 80302-080302.   DOI: 10.11889/j.0253-3219.2014.hjs.37.080302
Abstract336)      PDF(pc) (905KB)(1997)       Save
Background: Positron emission tomography (PET) is in rapidly developing as a powerful imaging technique for diagnosis, efficacy evaluation and prognosis of tumor. In contrast to 18F-FDG, the amino acid tracers were helpful additional tools for differentiating tumor tissue and inflammation, edematous, necrotic and fibrotic tissue because of their low uptake in those tissues, so that amino acid tracers appear to be more specific than the widely used 18F-FDG. As a result, a number of attempts have been undertaken for radio-synthesis of amino acid with short half-life nuclide 18F and 11C. Purpose: The aim is to review and discuss the present knowledge on synthesis methods and preliminary clinic application of labeling amino acid. Methods: The advances on the synthesis methods and preliminary clinic application of labeling amino acid in recent years were introduced and discussed. Results: In recent years, many new 18F or 11C-labeled amino acids have been developed and their preliminary clinic applications were studied. Conclusion: The review provides an overview of this class of radiolabeled amino acids and highlights the current synthesis status and the key preliminary clinic applications.
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Turbulent heat transfer of liquid metal inside the sub-channels of reactor core
GE Zhihao, PENG Yongsheng, LYU Yijun, DENG Weiping, ZHAO Pinghui
Nuclear Techniques    2015, 38 (9): 90603-090603.   DOI: 10.11889/j.0253-3219.2015.hjs.38.090603
Abstract447)      PDF(pc) (1254KB)(1991)       Save
Background: Liquid metal has been proposed as the coolant of the fourth generation nuclear reactor and the accelerator driven sub-critical system. Due to its low molecular Prandtl number (Pr), liquid metal differs from other coolants like water or gas in heat transfer. Purpose: This study aims to investigate the character of heat transfer of liquid metal inside the reactor core. Methods: Speziale-Sarkar-Gatski (SSG) Reynolds stress model was applied to the Computational Fluid Dynamics (CFD) prediction of liquid metal flow and heat transfer inside the sub-channels of the reactor core. Effect of different dimensionless parameters, e.g. Reynolds number (Re), Pr, Grashof number (Gr) and pitch-to-diameter ratio (P/D) on the turbulent heat transfer calculated results was investigated. Results: The dimensionless convective heat transfer coefficient (Nu), predicted by the CFD method, agrees well with the experimental data and the empirical relations. Conclusion: Based on the analysis of various dimensionless parameters, it is found that the heat exchange performs better in triangular fuel assembly sub-channels than that in square sub-channels, under the same condition of P/D and Re. The inhomogeneous circumferential distributions of temperature and heat transfer can be effectively improved by increasing Re and P/D or choosing coolants with large Pr. When Re is larger than 10000, the buoyancy effect on liquid metal heat transfer could be ignored.
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Synthesis of Dumbbell-like Au nanostructure and its light-absorbance study  
SHEN Jianlei, XU Yan, LI Kun, SONG Shiping, FAN Chunhai
Nuclear Techniques    2013, 36 (6): 60501-060501.   DOI: DOI: 10.11889/j.0253-3219.2013.hjs.36.060501
Abstract246)      PDF(pc) (9293KB)(1971)       Save

Background: By changing the size or the morphology of Au nanostructures, they can absorb different wavelength light due to the localized surface plasmon resonance (LSPR). Because Au nanorods show good ability to transform light into heat (photothermal effect), they have been wildly used to deliver the drugs and release them controllably. However, when applying such nanostructures for in vivo treatments, Au nanorods must have long aspect ratio which often make it hard to prepare heterogeneous nanostructures. Purpose: A new method to synthesize Au nanostructures with uniform size and to achieve long wavelength light absorbance is needed. This work attempts to synthesize such Au nanostructures by using bio-nano techniques. Methods: New nanostructures are prepared by growing Au nanoparticles on the surface of Au nanorods modified with DNA molecules. Results: Dumbbell-like Au nanostructures were prepared firstly. Its maximum absorbance locates at near ultraviolet region, which means that it can be used as a potential tool for the deep-skin photothermal treatment. Moreover, other two kinds of nanostructures, i.e. Au nanorods with Au splinter at two ends and sea urchin-like nanostructures, are also studied. Conclusions: We successfully fabricated novel Au nanostructures which can be used for drug delivery, surface-enhanced Raman spectroscopy and catalysis.

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Influencing factors of dose equivalence for X and γ rays with different energy based on Monte Carlo
GUO Huiping, LYU Wenhui, LYU Ning, WEI Zhihao
Nuclear Techniques    2014, 37 (01): 10203-010203.   DOI: 10.11889/j.0253-3219.2014.hjs.37.010203
Abstract297)      PDF(pc) (1144KB)(1950)       Save

Background: The accuracy of dosimeter measurement of X and γ rays needs to be resolved. Purpose: The aim is to study the correction term of the equivalent process of low-energy X-ray and the natural radioactive source. Methods: Instead of the standard sources, X-ray machine was adopted on the dose instrument calibration. The influence factors of the equivalence between low-energy X-ray and high-energy X or γ rays were simulated using Monte Carlo (MCNP) software. Results: The influences of distance, space scattering, response of detector on dose equivalence were obtained. The simulation results were also analyzed. Conclusion: The method can be used in dose equivalent correction for low-energy X-ray, high-energy X or γ rays, which is significant for the widespread use of X rays.

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Design and verification of test method for the single event effect in flash-based FPGA
YANG Zhenlei, WANG Xiaohui, SU Hong, LIU Jie, YANG Haibo, CHENG Ke, TONG Teng
Nuclear Techniques    2015, 38 (2): 20404-020404.   DOI: 10.11889/j.0253-3219.2015.hjs.38.020404
Abstract373)      PDF(pc) (2156KB)(1939)       Save
Background: With the increased application of Field Programmable Gate Array (FPGA) in the field of spaceflight, Single Event Effect (SEE) of FPGA is attracting more and more attentions recently. Purpose: The aim is to study single event effect in flash-based FPGA manufactured by Microsemi. Methods: VersaTile and RAM Block from the flash-based FPGA are selected as the research object. First of all, the simulation verification of the method was performed by using ModelSim toolkit. Then the experimental tests of FPGA samples were carried out using SEE testbed based on the Heavy Ion Research Facility in Lanzhou (HIRFL). Results and Conclusion: The simulation results verify that the test methods are effective, and the Single Event Upset (SEU) are detected timely and accurately. Experimental results on the SEE test base using 86Kr of HIRFL showed its rationality and validation.
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Cited: Baidu(5)
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Electron ion collider in China
Xu CAO, Lei CHANG, Ningbo CHANG, Xurong CHEN, Zhuojun CHEN, Zhufang CUI, Lingyun DAI, Weitian DENG, Minghui DING, Chang GONG, Longcheng GUI, Fengkun GUO, Chengdong HAN, Jun HE, Hongxia HUANG, Yin HUANG, Kaptari L P, Demin LI, Hengne LI, Minxiang LI, Xueqian LI, Yutie LIANG, Zuotang LIANG, Guoming LIU, Jie LIU, Liuming LIU, Xiang LIU, Xiaofeng LUO, Zhun LYU, Boqiang MA, Fu MA, Jianping MA, Yugang MA, Lijun MAO, Mezrag C, Jialun PING, Sixue QIN, Hang REN, Roberts C D, Guodong SHEN, Chao SHI, Qintao SONG, Hao SUN, Enke WANG, Fan WANG, Qian WANG, Rong WANG, Ruiru WANG, Taofeng WANG, Wei WANG, Xiaoyu WANG, Xiaoyun WANG, Jiajun WU, Xinggang WU, Bowen XIAO, Guoqing XIAO, Jujun XIE, Yaping XIE, Hongxi XING, Hushan XU, Nu XU, Shusheng XU, Wenbiao YAN, Wencheng YAN, Xinhu YAN, Jiancheng YANG, Yi-Bo YANG, Zhi YANG, Deliang YAO, Peilin YIN, Wenlong ZHAN, Jianhui ZHANG, Jinlong ZHANG, Pengming ZHANG, Chao-Hsi CHANG, Zhenyu ZHANG, Hongwei ZHAO, Kuang-Ta CHAO, Qiang ZHAO, Yuxiang ZHAO, Zhengguo ZHAO, Liang ZHENG, Jian ZHOU, Xiang ZHOU, Xiaorong ZHOU, Bingsong ZOU, Liping ZOU
Nuclear Techniques    2020, 43 (2): 20001-020001.   DOI: 10.11889/j.0253-3219.2020.hjs.43.020001
Abstract1100)   HTML88)    PDF(pc) (5822KB)(841)       Save

Lepton scattering is an established ideal tool for studying inner structure of microscopic particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High intensity heavy-ion accelerator facility (HIAF) which is currently under construction, together with an additional electron ring. The proposed collider will provide highly polarized electrons (with the polarization ~80%), protons and Helium-3 (both with the polarization ~70%), as well as unpolarized ion beams from carbon to uranium with viable center of mass energy from 15 GeV to 20 GeV and the luminosity of (2~4)×1033 cm-2?s-1. The main foci of the EicC will be the precision measurements of proton structure in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment, in particular, the short range correlation of nucleons and the cold nuclear matter effects; the exotic hadronic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with the cutting-edge technology. During preparation of the document, we have received valuable inputs and help from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and hadron physics as well as accelerator and detector technology in China.

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Research on atlas-based brain segmentation for HD integrated PET/MRI image
Zaisheng LI, Lingzhi HU, Qun CHEN
Nuclear Techniques    2019, 42 (10): 100301-100301.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100301
Abstract119)   HTML0)    PDF(pc) (1027KB)(89)       Save
Background

Integrated positron emission tomography (PET) / magnetic resonance imaging (MRI) is a multimodal imaging system which can acquire PET and MRI images simultaneously. Due to the unique advantages in reflecting the anatomical structure and physiological function, PET/MRI has been widely commonly used in diagnosis of many brain diseases. Brain segmentation is of great significance to the quantitative study of brain images and the common method used in clinical diagnosis is atlas-based brain segmentation, which can be applied to both MRI images and PET images. Brain segmentation based on atlas for integrated PET/MRI image system only needs one modelity as the segmentation results can be mapped to another modelity.

Purpose

This study aims to determine which modality should be used for atlas-based segmentation for high definition (HD) integrated PET/MRI image.

Methods

Comparative experiments with two image groups were designed and performed. In the first group, 150 PET images were registered to PET brain template to obtain brain segmentation. In the second group, 150 MRI images were registered to MRI brain template to obtain brain segmentation. Six regions were selected to calculate the dice value. Comparing the segmentation results of the two sets of images with their results based on first, the modality with a higher average dice value would be more suitable for atlas-based brain segmentation.

Results

In PET group, the dice values of six regions were 0.62, 0.55, 0.63, 0.62, 0.71 and 0.69, respectively. In MRI group, the dice values of six regions were 0.68, 0.64, 0.79, 0.81, 0.77 and 0.79. The error coming from registering PET images to PET brain template was larger than that of registering MRI images to MRI brain template.

Conclusions

PET-based segmentation accuracy is lower than MRI-based segmentation precision, hence the MRI image is more suitable for atlas-based brain segmentation.

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Intelligent commissioning system based on EPICS and differential evolution algorithm for synchrotron radiation beamline
Yingzhi SHI, Mei GAO, Wenhong JIA, Guangzhi YIN, Xingyu GAO, Yonghua DU, Lifang ZHENG
Nuclear Techniques    2020, 43 (5): 50101-050101.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050101
Abstract97)   HTML9)    PDF(pc) (1311KB)(167)       Save
Background

In synchrotron radiation facilities, it is important to keep beamlines operating in optimal conditions. The debugging process is normally very time consuming due to the irregular light source beam point, and it is not easy to get global optimum.

Purpose

This study aims to develop an intelligent debugging system based on Experimental Physics and Industrial Control System (EPICS) and differential evolution algorithm for synchrotron radiation beamline commissioning.

Methods

First of all, based on the differential evolution algorithm, intelligent optimization model of beamline was established. Then the automatic optimization of beam adjusting process was implemented by using LabVIEW program and communication with the EPICS-based control system was achieved by CaLab interface module. Functions of the user interface, motion control, algorithm implementation and evolution processing were integrated in the LabVIEW program. Finally, this intelligent commissioning system was tested at the X-ray diffractive (XRD) beamline of SSRF (Shanghai Synchrotron Radiation Facility) for optimization of the beam flux at sample position by adjusting the beamline optical components.

Results & Conclusions

Online tests results show that this intelligent commissioning system converges to the optimal solution quickly, and the convergence time is about 30 min, more than one order of magnitude higher than manual optimization efficiency.

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Design of charge sensitive preamplifier based on RC low pass feedback
Yi ZENG Guoqiang GE Liangquan HU Chuanhao HE Li HOU Yang LI Xinchi RONG
Nuclear Techniques    2019, 42 (9): 90402-090402.   DOI: 10.11889/j.0253-3219.2019.hjs.42.090402
Abstract94)   HTML2)    PDF(pc) (792KB)(74)       Save
Background

Traditional charge-sensitive preamplifiers use high-resistance resistors as low-frequency feedback circuit. The thermal noise introduced by high-resistance resistors is the main source of preamplifier noise.

Purpose

This study aims to design and develop a novel charge-sensitive preamplifier by using N-channel junction field effect transistor and RC (Resistor-Capacitance) low-pass network instead of traditional high resistance feedback resistor.

Methods

A junction field-effect transistor and an integrated operational amplifier were used to form an amplifying circuit with advantages of high input impedance and large open-loop gain. A high-pass loop was formed by a small capacitance capacitor to provide a high-frequency feedback loop for the circuit and integrates nuclear pulse current at the same time. The RC low-pass network constituted a DC (direct current) feedback loop to provide a stable DC operating point for the circuit, and a voltage divider for the N-channel junction field effect transistor operating in a forward bias state to realize a feedback capacitor for continuous discharge of its charge.

Results

The charge-sensitive preamplifier was connected with BPX66 Si-PIN detector and the 241Am source was measured at room temperature. The energy resolution of 3.03%@59.5 keV was achieved.

Conclusions

Compared with the traditional resistive capacitance feedback charge-sensitive amplifier, this circuit can effectively over-come the noise introduced by the large-resistance feedback resistor, especially for semiconductor detectors such as Si-PIN.

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Design and measurement of CTFEL magnets
Longgang YAN, Yuzhu CUI, Hao ZHANG, Derong DENG, Qing LI, Yingshun ZHU, Xingfan YANG, Ming LI
Nuclear Techniques    2019, 42 (10): 100203-100203.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100203
Abstract91)   HTML3)    PDF(pc) (1020KB)(52)       Save
Background

China Academy of Engineering Physics THz Free electron laser (CAEP THz FEL), referred to as CTFEL, is the first scientific facility in China that can provide users with high power and wide-spectrum terahertz waves. As an accelerator-based radiation source, magnet is one of the most important components for the transportation, measurement and manipulation of electron bunch.

Purpose

This study aims at the design and measurement of magnets to satisfy that requirements of CTFEL.

Methods

According to the specifications of CTFEL magnets, the magnet system was designed to consist three solenoids, three 45° dipoles, one 90° dipole, six circular quadrupoles and six square quadrupoles. The problems of design and their solution schemes were described. The magnetic field distribution, integral field distribution, transverse field distribution and magnetic axis were measured.

Results & Conclusion

The test results show that all magnets satisfied the specification requirements. At present, all magnets have been completely installed and commissioned to ensure the laser operation of the CTFEL facility.

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Simulation study on scattering interference in 60Co dual-projection radiation imaging system based on Monte Carlo method
Minzi NI, Zhentao WANG, Peng CONG, Litao LI
Nuclear Techniques    2020, 43 (4): 40202-040202.   DOI: 10.11889/j.0253-3219.2020.hjs.43.040202
Abstract89)   HTML9)    PDF(pc) (1056KB)(48)       Save
Background

In 60Co dual projection radiation imaging system, the radiation sources are arranged at the bottom and side while their corresponding ionization chamber detectors are set respectively in the gantry. With the synchronous movement of the sources and the gantry, the system can obtain both side-view and upward-view images of the objects simultaneously. However, due to the presence of scatter, the imaging of the two projection planes will interfere with each other.

Purpose

This study aims to reduce the effect of scattering between two projection planes and improve the imaging quality of the system by using Monte Carlo method.

Methods

Firstly, a simulation model based on Monte Carlo method was established, and its reliability was verified by comparing the simulation data with the experimental data of the scattering distribution at no-load. Secondly, the scattering effects of different projection plane spacings, different shielding materials (tungsten, lead, steel, and aluminum) around the detector with different installation positions, and thickness of the shielding layer on the scatter were calculated based on the model built. Finally, shielding correction effect of 2.5 cm thick lead layer was evaluated.

Results

Simulation results show that when the projection plane spacing is 40 cm and 80 cm, the scattering can be reduced to less than 55% and 40% of that of the 10 cm plane spacing respectively. When projection plane spacing is 40 cm, a lead shield placed between the gantry support and the side-view ionization chambers can achieve best shielding effect at the same thickness compared with steel and aluminum. When the thickness of the lead is 2.5 cm, scattering will be further reduced by 80%.

Conclusions

This study provides a reference and guidance for the hardware improvement and upgrade of the dual-projection system for scattering correction.

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A survey of heatpipe space nuclear reactor power supply
Ao WANG, Fengyang SHEN, Gu HU, Jian AN Weijian GUO
Nuclear Techniques    2020, 43 (6): 60002-060002.   DOI: 10.11889/j.0253-3219.2020.hjs.43.060002
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Background

With the in-depth exploration of space, the power supply requirements for energy supply are gradually increasing. Space nuclear reactor power supply stands out in the deep space exploration mission due to its advantages of passivity, long life and high reliability, hence heat pipe nuclear reactor has become the focus of research in the field of space nuclear reactor.

Purpose

This study aims to evaluate the progress and technology of heat pipe space nuclear reactor used as power supply.

Method

First of all, the conceptual design of heatpipe reactor in the early stage and its application in Kilopower was summarized. Then the details of heatpipe power system (HPS), the heatpipe-operated mars exploration reactor (HOMER), safe affordable fission engine (SAFE) and Kilopower were investigated with emphasis on the structure design, fuel selection, heatpipe arrangement and power design of each reactor.

Results

This survey provides ideas and references for future research and design of heatpipe space nuclear reactor power system.

Conclusions

The design of heatpipe reactor is highly flexible and innovative. The use of different alkali metal heat pipes and thermoelectric conversion methods has a direct impact on the system power and the quality of the entire system. The combination of heat pipe and various thermoelectric conversion methods can be attempted.

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Development and verification of a coupled code of steady-state neutronics and thermal-hydraulics for molten salt fast reactor
Bin DENG, Jingen CHEN, Long HE, Shaopeng XIA, Chenggang YU, Xiangzhou CAI
Nuclear Techniques    2019, 42 (11): 110602-110602.   DOI: 10.11889/j.0253-3219.2019.hjs.42.110602
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Background

There is a strong coupling between the neutronics and thermal-hydraulics in the non-moderated can-type core of molten salt fast reactor (MSFR).

Purpose

This work aims to develop and verify coupled code for steady-state neutronics and thermal-hydraulics for the MSFR.

Methods

The coupling code was developed using python programming language to exchange the power distribution, fuel salt temperature and density distributions between OpenMC (Monte Carlo particle transport simulation code) and OpenFOAM (computational fluid dynamics software). Based on the coupling code, a benchmark model of MSFR was established, and the effects of the number of neutonics region division and the different initial conditions on the k eff, fuel salt velocity and temperature distributions were studied. Finally, the simulation results were compared with the reference results of MSFR.

Results

The three-dimensional power distribution, neutron flux distribution, fuel salt velocity field and temperature field distributions can be obtained by using this coupled code. The benchmark of MSFR shows that different initial conditions have no effect on k eff, and an alternative number and scheme of neutronics region division are recommended. The simulation results keep a good agreement with the reference results of MSFR.

Conclusions

This coupled code can provide reliable results for the steady-state neutronics and thermal-hydraulics coupling of MSFR.

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Design of a cryo-cooled double multilayer monochromator in USAXS beamline at SSRF
Xiaopei SUN, Wanqian ZHU, Zhongmin XU, Hongliang QIN
Nuclear Techniques    2019, 42 (11): 110101-110101.   DOI: 10.11889/j.0253-3219.2019.hjs.42.110101
Abstract84)   HTML17)    PDF(pc) (1072KB)(186)       Save
Background

A double multilayer monochromator (DMM) is required in the time-resolved ultra small angle X-ray scattering (USAXS) beamline during Shanghai Synchrotron Radiation Facility (SSRF) phase II construction.

Purpose

This study aims at the structure design of DMM for the USAXS beamline of SSRF to satisfy the requirements.

Methods

Based on condition of indirectly cooled by liquid nitrogen, thermal slope error of the multilayer was analyzed and detailed mechanical design of the DMM was introduced. Based on the analysis of the errors caused by the multilayer crystal optics attitude adjustment and the planar four-bar motion mechanism, a Sinbar mechanism based on Pivot and bearing rotating was designed for the DMM. [Results &

Conclusion

Basical analysis and calculation results show the design scheme can meet the requirements of monochromator stability and ultra-high angle resolution. At present, the monochromator is manufacturing and its performance will be tested and reported in the future.

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Design of the super-small angle Canted front-end at SSRF
Dandan JIA, Min ZHANG, Yongjun LI, Shuai WU, Limin JIN, Song XUE
Nuclear Techniques    2019, 42 (9): 90101-090101.   DOI: 10.11889/j.0253-3219.2019.hjs.42.090101
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Background

The current beam lines structure design cannot satisfy the requirement of the first combined beamline station with soft and hard X-rays in Shanghai synchrotron radiation facility (SSRF).

Purpose

This study aims to design the super-small angle Canted front-end at SSRF to support a wide-energy-range experimental platform with multiple methods for energy material research.

Methods

Two undulators, elliptical polarization undulator (EPU) and in vacuum undulator (IVU), were employed in the wide-range energy material beamline (E-Line) that contains soft and hard X-rays located in the straight line with a Canted angle of 2 mrad. The separated plane mirror, SM1, was designed to be located at the front-end. After SM1, the soft line was deflected 2.4°, allowing two dedicated beam lines to be set.

Results

The two beam lines share the front-end components, and can independently operate the components of the front-end. The front-end of E-Line adopt a new structure and layout different from the standard ones that can handle the heat load up to 7.81 kW. Compared with the key equipment of other common insert device front-end with only one through-light aperture, the one of this front-end was designed with two through-light apertures.

Conclusion

The installation of E-Line front-end has been accomplished, and the structure and layout fully satisfy the technical requirements of the beamline.

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Analysis and evaluation of stress relaxation for the high temperature bolt connecting structure in scram system of the TMSR-LF1
Zuokang LIN, Wen WANG, Huiqing FAN, Maoyuan CAI, Lifang ZHAI, Xiaochun ZHANG
Nuclear Techniques    2019, 42 (10): 100601-100601.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100601
Abstract83)   HTML2)    PDF(pc) (998KB)(103)       Save
Background

The temperature of the bolt connecting structure is around 650 ℃ in the scram system of the thorium molten salt reactor-liquid fuel 1 (TMSR-LF1) and the connecting components include three kinds of material, which have different coefficients of thermal expansion. Thermal expansion during the heating process, from room temperature to 650 ℃, and creep in the long lifetime of reactor will affect the bolt pretension, which may touch the safety of the scram system.

Purpose

This study aims to analyse the stress relaxation of the bolting structure, and assess structural safety for the scram system of TMSR-LF1.

Methods

The ANSYS program was employed for the mechanical analysis of the bolt connecting model. The stress analysis and creep stress-relaxation analysis of the structure under the combined action of bolting preload and thermal expansion were performed.

Results

The high temperature creep of bolted structural materials and the variation of stress relaxation caused by the creep and its influence on the pre-tightening force of bolted connection structures are obtained for the whole lifetime of the reactor. And the evaluation of the bolt is completed under.

Conclusions

According to American society of mechanical engineers (ASME) standard in coordinate with ASME-III-5-HBB rules for bolt mechanical analysis and safety evaluation, the connecting bolt structure designed for TMSR-LF1 is demonstrated safe and reliable in the whole lifetime.

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MCNP simulations of medical diagnostic X-ray spectra
Yan KONG, Weihai ZHUO, Bo CHEN, Chao ZHAO
Nuclear Techniques    2019, 42 (11): 110301-110301.   DOI: 10.11889/j.0253-3219.2019.hjs.42.110301
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Background

In medical diagnostic radiology, detailed knowledge of X-ray spectra is required for evaluating the image quality and patients’ or staff’s radiation dose.

Purpose

This study aims to simulate medical diagnostic X-ray spectra by using Monte Carlo method.

Methods

First of all, a simplified X-ray machine head geometry model was constructed in MCNP (A general Monte Carlo N-Particle transport code) software. Then, the X-ray spectra and surface source data files in the output window were calculated under tube voltage ranging from 50 kVP to 150 kVP, filter ranging from 0.5 mm (Al) to 5 mm (Al) and anode angles ranging from 6° to 14°.

Results

Database of medical diagnostic X-ray spectra and surface sources in the output window are obtained by various machine X-ray head parameters. The calculated spectra are comparable to those of other X-ray spectra software.

Conclusions

X-ray source and its spectra can be correctly simulated by electronically hitting the target through Monte Carlo simulation, providing a basis for future applications.

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Smoothing analysis of the particle accelerator beam orbit by moving least squares
Zhonghe LIU, Zongchun LI, Yinggang GUO, Hua HE, Wenbin ZHAO
Nuclear Techniques    2019, 42 (10): 100202-100202.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100202
Abstract77)   HTML0)    PDF(pc) (1060KB)(64)       Save
Background

The particle accelerator has a short downtime and requires high relative accuracy between magnets.

Purpose

This study aims to improve the smoothing analysis efficiency of beam orbit by using moving least squares method.

Methods

Firstly, the original smoothed data was preprocessed to make the ring magnet data linearly distributed. Secondly, the fitting area was meshed, the grid points were extracted and the appropriate basis function and weight function were selected. Then, three indicators of the smooth analysis were given and the whole calculation process was designed. Finally, the smoothing effects of the averaging method, the least squares fitting and iteration method and the method of this paper were compared and analyzed by simulation data.

Results

The experimental results show that the fitting curve obtained by the method of this paper is the smoothest and the magnet adjustment times are the least under the same conditions.

Conclusions

To a certain extent, the adjustment time is saved and the adjustment efficiency is improved.

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Reconstruction of point spread function of incoherent light by redundant information extraction and its application in synchrotron radiation imaging system
Huijuan XIA, Yanqing WU, Lei ZHANG, Yuanhe SUN, Renzhong TAI
Nuclear Techniques    2020, 43 (1): 10101-010101.   DOI: 10.11889/j.0253-3219.2020.hjs.43.010101
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Background

The point spread function (PSF) of X-ray indirect imaging system is difficult to measure accurately through experiments, and the theoretical construction process is complex, hence it is difficult to meet the actual situation, resulting in poor image quality.

Purpose

This study aims to obtain the PSF of X-ray indirect imaging system by reconstructing PSF with redundant information to obtain a more accurate PSF under incoherent illumination.

Methods

First of all, theoretical analysis was performed for the measuring problem of incoherent optical PSF. Since the optical transfer function (OTF) was the fourier transform of PSF, and coherent transfer function (CTF) was closely related to OTF, nonlocality of incoherent optical information distribution was used to reconstruct the central region of the PSF. Then, the redundent information in a 2D grating scintillation imaging system was extracted to reconstruct the PSF by converting incoherent diffraction field to coherent diffraction field. Finally, experimental data obtained from BL13W beamline station of Shanghai synchrotron radiation facility (SSRF) were employed to evaluate PSF and image restoration results of scintillator imaging system.

Results

Experimental results of synchrotron radiation imaging show that this method can recover the image more accurately than other PSF measurement methods.

Conclusion

The PSF reconstructed by redundant information method can not only restore the image accurately, but also avoid a lot of complex problems.

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Data acquisition system for single photoelectron spectra of photoelectric detector
Feng GAO, Sen QIAN, Zhe NING, Zhigang WANG, Lishuang MA, Yao ZHU, Pengyu CHEN, Shiyu YIN, Zhile WANG
Nuclear Techniques    2019, 42 (10): 100404-100404.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100404
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Background

There are two methods to test the single photoelectron spectra (SPE) performance of the photomultiplier tubes (PMT) and Silicon Photomultiplie (SiPMT) with either the charge-to-digital-converter (QDC) module or flash amplitude-to-digital-converter (FADC) module.

Purpose

This study aims to investigate the difference of data acquisition between FADC and QDC for single photoelectron spectra (SPE) of photoelectric detector.

Methods

Single photoelectron spectra (SPE) of 20-inch PMTs of the same model, as well as SiPMT of same mode, were measured under the same testing conditions using FADC module and QDC module. Gain, signal events, detection efficiency, the ratio of peak to valley and energy resolution were compared in details.

Results

Both QDC and FADC can be used as data acquisition tools for PMT SPE test, but each has its own advantages and disadvantages.

Conclusions

According to the system’s specific demand for photoelectric detector, either of the two modules could be chosen.

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Study on flow friction characteristics of single-phase flow in annular narrow channel
Jun PENG
Nuclear Techniques    2019, 42 (10): 100603-100603.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100603
Abstract75)   HTML1)    PDF(pc) (1479KB)(32)       Save
Background

Eccentricity in the manufacture and assembly of nuclear fuel assemblies will affect the annular channel.

Purpose

This study aims to investigate the characteristics of the single-phase flow in narrow annular channels.

Methods

Computational fluid dynamics (CFD) simulation on single-phase flow friction characteristic in straight annuli channel with different width (h=0.775~1.742 mm, 0.69<r i/r o<0.86) in ranges of laminar flow (300<Re<1 800) and fully developed turbulent flow (104<Re<105) were carried out by commercial code FLUENT. The influence of different eccentricity (e=0.01~0.5) was also considered.

Results

The results show that for laminar flow the simulated friction factors are completely agreed with that of the analytic solution. When the Reynolds number is in the range of 104~5×104, the Blausius correlation achieves more exact results with CFD; and while the Reynolds number is in the range of 5×104~105, the McAdams correlation gets more consistent results with CFD.

Conclusions

Based on the above conclusions, proposed correlation f=0.257 5Re -0.23 can well predict in the whole Reynolds number in the range of 104~105. Furthermore, the friction factor is a function of eccentricity, a relatively weak function of width, and independent of the Reynolds number.

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Development of a SiPM-based practical plastic scintillation fiber dosimeter
Cuiping YANG, Jie XIN, Dongdong ZHOU, Yiqiu LI, Lin CHAI, Simei YOU, Baoguo ZHANG, Wanxin WEN, Ming ZHANG, Rensheng WANG
Nuclear Techniques    2019, 42 (10): 100402-100402.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100402
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Background

A real-time, high position resolved in-vivo dose measurement of critical health tissues and tumors is one of the most direct quality assurance (QA) tools in the radiotherapy. Plastic scintillator fiber dosimeters (PSFDs) have great advantages in dose verification due to its small size, good radiation resistance and good tissue equivalence.

Purpose

This study aims to develop a plastic scintillation fiber dosimeter (PSFD) based on silicon photomultiplier (SiPM), and investigate its performance in clinical applications.

Methods

With a stable LED pulse optical source, the leakage current of SiPM was measured by the picoammeter. Time stability and repeatability of the dosimeter, temperature response and the influence of the transmission fiber curvature on the SiPM leakage current were systematically studied. The dynamic range of the dosimeter was measured by using a small animal radiotherapy machine and LED pulse optical source.

Results

The results show that the leakage current changes <1% when the dosimeter works continuously for 8 h at constant temperature of 20 ℃, and the leakage current changes <0.5% during 32 h of intermittent operation. When the temperature change is less than 0.5 ℃, or the transmission fiber radius of curvature is greater than 11 cm, the output current change is less than 1%. The linear dynamic range of the dosimeter measurement is 100~9 000 cGy?min-1.

Conclusions

The developed dosimeter basically meets the accuracy requirements of the clinical dose verification.

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Simulating the effect of Prebuncher-Chopper on pulsing slow positron beam
Longpeng LIU, Fuyan LIU, Shilun PEI, Peng KUANG, Baoyi WANG, Peng ZHANG, Huaiqiang ZHANG, Xingzhong CAO
Nuclear Techniques    2019, 42 (9): 90202-090202.   DOI: 10.11889/j.0253-3219.2019.hjs.42.090202
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Background

Slow positron annihilation lifetime spectrum measurement is an important analytical method for high sensitivity and non-destructive detection of material micro-defects. Pulsed positron system is the core component of this technology.

Purpose

This study aims to obtain periodic positron pulses with high time resolution for lifetime measurement and to provide a signal marking the time of positron generation.

Methods

In this paper, the Parmela program was applied to simulate and calculate the effect of different beam parameters on positrons bunching based on the “Prebuncher-Chopper” pulsed system. Effect of different beam parameters on 150 ps (half-width) bunching was simulated and compared with calculation results of “Prebuncher-Chopper” bunching system.

Results

The results show that increasing beam energy, reducing beam energy spread and reducing beam spot size are beneficial to improve pulse efficiency. Moreover, when the positron beam energy is greater than 500 eV, the energy spread is less than 5 eV and the beam spot is less than 12 mm, the positron utilization ratio is more than 20% and the bunching efficiency is more than 85% using “Prebuncher-Chopper” pulsed system.

Conclusion

In contrast to the “Chopper-Prebuncher” system, “Prebuncher-Chopper” pulsed system can provide a higher positron utilization rate under the same beam parameters. Meanwhile, the time resolution (≤150 ps) and the bunching efficiency (≤85%) meet the measurement requirement.

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Conceptual design of Mars molten salt reactor
Shihe YU, Qiang SUN, Heng ZHAO, Rui YAN, Yang ZOU, Bing LAN
Nuclear Techniques    2020, 43 (5): 50603-050603.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050603
Abstract74)   HTML6)    PDF(pc) (689KB)(58)       Save
Background

Mars exploration has recently become a mainstream trend in space research. The establishment of a Mars base is an inevitable choice for human to study and develop Mars. Compared with the solar energy storage system, the nuclear reactor as a Mars base energy system has significant advantages in terms of system mass, operational flexibility, and environmental robustness.

Purpose

This study aims to propose core design scheme of Mars molten salt reactor (M2SR-1) and calculation model in aspects of reactor physics, critical safety and thermal.

Methods

The Monte Carlo N Particle Transport Code (MCNP) and Oak Ridge Isotope Generation and Depletion Code (ORIGEN) were employed to establish core physical calculation model. Calculation and analysis were performed in aspects of physical, safety, thermal and so on.

Results

Computational results reveal that the scheme of M2SR-1 meets the requirement of 8-year-life under full power operation. Under different hypothesis falling environments, the effective multiplication factor of nuclear reactor is less than 0.98, satisfying the criticality safety requirements.

Conclusion

This study provides basic theoretical reference for the design of planet surface molten salt reactor.

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Design of novel lead-free flexible composites for radiation protection and simulation of protective effect
Siqi YAN, Peng CHENG, Guangyi YU, Hanzhou LIU, Churan FEI, Xiaoping OUYANG
Nuclear Techniques    2020, 43 (5): 50201-050201.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050201
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Background

The number of radioactive practitioners has increased rapidly due to the wide application of X-ray, resulting in widespread attention to radiation protection. Lead is commonly used as a shielding material, but is extremely toxic and harmful to human health. The lead-based protective clothing on the market is too heavy and uncomfortable to wear.

Purpose

This study aims to design flexible composites of lead-free for shielding X-ray of different energy ranges and evaluating its shielding effect.

Methods

The X-ray mass attenuation coefficients of high atomic number materials were calculated according to National Institute of Standards and Technology (NIST) method. Hence, the ideal functional fillers were selected as shielding materials instead of lead. The MCNP5 code was employed to evaluate protective performance of lead-free flexible composites consisting of various doped metal elements with high atomic number.

Results

Simulation results show that Bi doping is an ideal substitute for Pb doping, and Bi2O3 can be used as the first-rate functional filler in lead-free flexible composites. Shielding performance of the composite doped with Bi2O3 and Gd2O3 is obviously improved during the energy of 54~66 keV whilst the composites doped with Bi2O3 and W functional fillers achieve the best X-ray attenuation at around 70 keV of X-ray.

Conclusions

A variety of bismuth-based flexible composites have been designed to replace lead-based materials. Bi2O3 is the optimal filling material for X-ray scattering energy less than 54 keV, incorporation of two functional materials, Bi2O3 and Gd2O3, can effectively improve the absorption effect of the composites for X-ray scattering energy in range of 54~66 keV. In the energy range of 66~100 keV, incorporation of two functional materials, Bi2O3 and W, is the optimal filling method whilst it is best to fill Bi2O3 alone to shield X-ray scattering energy greater than 100 keV.

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Development of U-shaped carbon foil in medical heavy ion accelerator
Fengqiong LIU, ZiWei LU, Hongbin ZHANG, Xinjuan RONG, Ronghua LI, Haixia LI, Zhankui LI, Xiuhua WANG
Nuclear Techniques    2019, 42 (10): 100201-100201.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100201
Abstract71)   HTML0)    PDF(pc) (811KB)(65)       Save
Background

Carbon stripping foil as a stripper is one of the important components of medical heavy ion accelerator. It is essential to develop the carbon stripping foil that meets the requirements of medical heavy ion accelerators.

Purpose

This study aims to develop U-shaped carbon foil for medical heavy ion accelerator.

Methods

AC carbon arc discharge method was employed to develop the carbon stripping foil, and its properties were measured by the methods of scanning electron microscopy (SEM) and Raman characterization. The “U-shaped” target frame was used to ensure that target frame did not affect the normal operation of ions in the injected ring. The edge of target frame was designed to be as narrow as 2 mm wide, and the effective area of the carbon stripping foil was 1 600 mm2 (40 mm × 40 mm).

Results

The thickness of the carbon stripping foil is 15 μg·cm-2, and the thickness uniformity is 97.65%. The SEM test results show that the surface of the carbon stripping film is smooth and the internal structure is compact. The Raman test results show that the G peak near 1 580 cm-1 is stronger than the D peak located near 1 300 cm-1, indicating the degree of graphitization of the film is higher, and the 2D peak near 2 700 cm-1 is weak, indicating that the number of graphite molecules is higher.

Conclusion

The carbon stripping foil developed in this study has a certain mechanical toughness thereby completing the automatic mold changing process of the carbon stripping foil.

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Design and implementation of neutronics computing cloud platform based on SaaS mode
Zhongyang LI, Bin WU, Shengpeng YU, Lijuan HAO, Jing SONG, Pengcheng LONG, Yican WU
Nuclear Techniques    2019, 42 (10): 100604-100604.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100604
Abstract70)   HTML2)    PDF(pc) (820KB)(53)       Save
Background

The high-fidelity nuclear reactor model requires a large amount of computing resources and a high-performance computing platform. High-performance computing platforms are cumbersome to operate and are not conducive to designers, while the cloud platform has the characteristics of super large scale and easy to use, hence has good application value for neutronics calculation.

Purpose

This study aims to establish a neutron computing cloud platform for users.

Methods

Combined with cloud computing technology, a neutron computing cloud platform based on Software as a Service (SaaS) mode was designed and implemented. Neutronics computing functions and related databases were set up to run in the cloud to provide SaaS mode computing services for end users.

Results

Users can use computing resources anytime and anywhere through the browsers to effectively improve the efficiency of neutronics calculation.

Conclusions

The cloud platform proposed in this paper can be used for general nuclear design computation.

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The study on the gain of microchannel plate
Xiaodong ZHANG, Xiaoping OUYANG, Junzhang HE, Chen WEI, Xiufeng WENG, Xinjian TAN, Zhuming FU
Nuclear Techniques    2019, 42 (10): 100403-100403.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100403
Abstract68)   HTML3)    PDF(pc) (744KB)(51)       Save
Background

Microchannel plate (MCP) is an electron multiplier device with an ultra-fast time response, which can be directly used for the detection of charged particles. The gain of MCP has a large influence on the properties of the neutron detector.

Purpose

This study aims to investigate the gain of the MCP through theoretical simulation and experimental test.

Methods

First of all,a sub-ns time-response neutron detector based on recoiled proton and MCP was developed for experimental test.The Monte Carlo method was used to simulate the number of secondary electrons generated by a single electron multiplying on a single microchannel, and the electron gain of a single-chip MCP at different voltages was calculated. Then, the gain characteristics of two MCPs were studied by alpha particle experiments.

Results

The calculation results show that the theoretical gain of a single-chip MCP is consistent with the MCP factory inspection report. The experimental results show that when the supply voltage of each MCP is 800 V, the gain of double MCP is about 9.0×106.

Conclusions

The method clarified in the paper is reliable and feasible, and provides a new technical approach for the study of MCP gain. It also provides a theoretical basis for studying the performance of MCP neutron detectors.

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Calculation and analysis of neutron and gamma shielding performance based on boron-containing stainless steel materials
Yu ZHANG, Yingming SONG, Xiaohang YU, Jian SHI, Zhonghang XU, Yan WANG, Mengting FU
Nuclear Techniques    2019, 42 (9): 90201-090201.   DOI: 10.11889/j.0253-3219.2019.hjs.42.090201
Abstract67)   HTML3)    PDF(pc) (1063KB)(60)       Save
Background

The simulation calculation of shielding performance of radiation protection materials at home and abroad is usually limited to one simulation of the Monte Carlo method, while the fine-grained calculation of gamma ray shielding of secondary products is less.

Purpose

This study aims to analyze shielding performance and activation products of boron-containing stainless steel materials.

Methods

Monte Carlo particle transport program combined with fuel consumption calculation and analysis program (MCNP5/ORIGEN2.1) was employed to calculate and analyze the shielding properties and activation products of stainless steel materials for radiation protection. Combined with the specific requirements of radiation shielding design, evaluation method of neutron/gamma integrated shielding performance was proposed. Based on the simplified model of three-layer shielding structure of single-layer external irradiation of nuclear reactor, the shielding effect of neutron in the neutron/γ mixed radiation field, photon, (n, γ) reaction photons and secondary activation product photons inside the material were simulated by boron stainless steel and ordinary stainless steel, and the overall shielding performance of the protective material was evaluated.

Results & Conclusions

The actual average photon transmittance of boron stainless steel is slightly lower than that of ordinary stainless steel, both of them have the same gamma-ray shielding performance, but boron stainless steel has advantages over ordinary stainless steel in weight reduction.

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Study of the measurement of the thickness of diffusion aluminizing layer based on X-ray fluorescence
Jichao LIU, Cheng WANG, Pengli DAI
Nuclear Techniques    2020, 43 (2): 20201-020201.   DOI: 10.11889/j.0253-3219.2020.hjs.43.020201
Abstract63)   HTML7)    PDF(pc) (1028KB)(39)       Save
Background

Aluminizing is often used as a protective coating for aero-engine turbine blades, but the current nondestructive testing equipment can not achieve accurate measurement of the coating thickness. The uniformity of aluminizing thickness has a great impact on the performance of turbine blades and the safety and stability of engine.

Purpose

This study aims to develope a nondestructive measurement method for the thickness of diffusion aluminized layer based on X-ray fluorescence absorption.

Methods

First of all, according to the theoretical calculation formula of X-ray fluorescence absorption, the linear relationship between the logarithm of the fluorescence intensity ratio (lnR) and the thickness of the fluorescence penetrating material (x) was obtained. Then a unitary linear regression model related to the main elements of K403 alloy and a multiple regression model based on the forward selection variable method were established. Finally, the comparative study of the prediction results of the two models was carried out.

Results

The experimental results show that the multi regression calculation model is relatively stable in comparison with the unitary regression calculation model, and the average relative error of measurement results under different thicknesses is only 3.2%.

Conclusions

The proposed method provides a convenient and feasible guiding idea for solving the problem of measuring the thickness of diffusion permeable layer.

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Study on the breeding characteristics study of chlorine and fluorine salt fast reactor
Xuemei ZHOU, Dongguo LI, Liaoyuan HE, Guimin LIU
Nuclear Techniques    2020, 43 (4): 40001-040001.   DOI: 10.11889/j.0253-3219.2020.hjs.43.040001
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[Background and

Purpose

The molten salt fast reactor is one of the advanced nuclear energy systems which has attracted much attention because of its outstanding advantages in fuel proliferation, nuclear waste transmutation and inherent safety. Liquid fluorine salt or chlorine salt is usually used as fuel carrier salt and coolant in molten salt fast reactor, which has high breeding properties.

Methods

Based on the dual-fluid molten salt reactor core structure, a comprehensive simulation program SCALE (Standardized Computer Analyses for Licensing Evaluation) were adopted to simulate and calculate the U-Pu fuel breeding ratio of two kinds of fluorine-salt fast reactors and one chlorine-salt fast reactor under the same metal solubility.

Results

The breeding ratios of different breeding and reflecting layers were simulated, and the changes of neutron energy spectra in fission and breeding zones were analyzed. The breeding ratio of chlorine salt fast reactor increases with the increase of the thickness of the breeding layer and the reflector layer, but the growth rate decreases. When the thickness of the breeding layer of the fast reactor is small, the variation of the breeding layer has little effect on the breeding ratio. When the thickness increases to 60 cm, the variation of the breeding layer thickness has almost no effect on the breeding ratio. The variation of reflector size has no effect on the breeding ratio. The critical state of the reactor core and the neutron energy spectrum in the fission region are not affected by the thickness of the breeder layer and the reflector layer.

Conclusions

At the same temperature and molar ratio, chlorine fast reactor has higher U-Pu fuel breeding ratio than fluorine fast reactor. This provides a theoretical basis for basic salt selection and size design for molten salt fast reactor diffusion.

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Stress analysis and structural analysis and optimization of high temperature molten salt pump in TMSR-SF0 based on ANSYS
Huiqing LIN Liangcheng CAI Maoyuan HUANG Chaochao ZHANG Xiaochun FU Yuan FAN
Nuclear Techniques    2019, 42 (9): 90604-090604.   DOI: 10.11889/j.0253-3219.2019.hjs.42.090604
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Background

High temperature molten salt pump, the design temperature can go up to 700 °C, is one of the key equipment in the primary loop in the simulator of Thorium-based Molten Salt Reactor with Solid Fuel (TMSR-SF0). The structural integrity of the pump is crucial to the safe operation of the reactor.

Purpose

This study aims to reduce the load-controlled stress level of the molten salt pump tank of TMSR-SF0 to meet the evaluation requirements of American Society of Mechanical Engineers (ASME) BPV code.

Methods

Three different schemes of the reinforcing rib for the bottom flat head including triangular shape, #-shape, and dual-#-shape were proposed and analyzed to optimize the initial tank design. The influence of the reinforcing rib spacing on the stress of pump tank in the dual-# scheme had been studied, and the optimal combination of parameters was found. According to the results of above analyses, the final tank design scheme was obtained, and then evaluated in accordance with ASME BPV code section III, Division 5.

Results

The results show that all of the three schemes can significantly reduce the stress level of the pump tank, dual-#-shape scheme was the best, and then followed by the #-shape scheme and triangular shape scheme.

Conclusions

The final reinforcing rib design scheme for the bottom flat head of the pump tank is a dual-# scheme, which can reduce its stress from 413.4 MPa to 65.4 MPa, with a drop of 84.2%, and meet the stress assessment limit of ASME standard.

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Evaluation of super homogenization method for pin-by-pin core calculation
Bin ZHANG, Yunzhao LI, Hongchun WU
Nuclear Techniques    2020, 43 (6): 60001-060001.   DOI: 10.11889/j.0253-3219.2020.hjs.43.060001
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Background

The new generation of pin-by-pin calculation method has gradually become the state-of-the-art approaches along with the improvement of computer technology and the development of core design.The difference between the pin-by-pin calculation and the traditional two-step scheme leads to the homogenization technique difficult to implement.

Purpose

This study aims to evaluate super homogenization techniques for pin-by-pin core calculationwith emphasis on equivalent homogenization constants.

Methods

Super homogenization method was used as one of the main homogenization techniques of pin-by-pin calculation. For fuel assembly, the traditional super homogenization method was employed to generate the group constants. For reflector assembly with neutron leakage, the super homogenization method related to space leakage was applied to the generation of equivalent homogenization constant including super homogenization factor.

Results

Based on the three-dimensional C5G7 benchmark, the application performance of the super homogenization method in pin-by-pin calculation is evaluated. The eigen-value relative error of pin-by-pin calculation is -0.001 6, assembly-power and pin-power relative errors are less than 5.5%.

Conclusions

Numerical results showed that the pin-by-pin calculations have the higher accuracy than the assembly-homogenized results.

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Preliminary design of beam dump for CEPC-linac
Haoyu SHI, Qingbin WANG, Zhongjian MA, Yadong DING
Nuclear Techniques    2019, 42 (10): 100204-100204.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100204
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Background

Circular electron positron collider (CEPC) is a high-energy accelerator, some beam produced by CEPC but not injected to energy intensifier need to be absorbed properly to keep the safety of the machine and the environment.

Purpose

This study aims to design the beam dump, and give a process of design for the beam dumps used in high-energy accelerators.

Methods

The Monte-Carlo program FLUKA was employed for the preliminary design scheme of CEPC linac beam dump. As the basis of absorber design, different calculating methods of beam range was proposed and checked with Empirical formula.

Results

The relationship between material selection of shield and overall shielding thickness is revealed. The introduction of variance reduction technique improves the accuracy of calculation results.

Conclusions

The empirical formula to estimate the stop range of electron is basically correct and same with the Monte-Carlo simulation. And the design itself is helpful to CEPC Project.

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Theoretical research on location of fuel assemblies failure using the activity ratio of134Cs and 137Cs
Lin ZHU, Guanglei LIU, Jingjing LIU
Nuclear Techniques    2019, 42 (10): 100602-100602.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100602
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Background

It is very important to locate ruptured fuel assemblies rapidly and accurately not only for emergency core refueling, but also for shortening critical path of overhaul.

Purpose

This study aims at location of fuel assemblies failure using the activity ratio of 134Cs and 137Cs.

Methods

The relationship between the ratio of 134Cs to 137Cs activity and fuel consumption in the fuel assembly was theoretically calculated, and the theoretical model was modified by ORIGEN software.

Results & Conclusions

It is found that the activity ratio of 134Cs to 137Cs increases with the increase of the burn-up, and decreases with the increase of fuel assembly enrichment. With the improved 134Cs to 137Cs activity ratio and burnup model, the burnup of damaged fuel assemblies at different enrichment levels in pressurized water reactor (PWR) nuclear power plants can be determined, and then the damaged fuel assemblies can be quickly located.

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Study of the detection unit of the calorimeter for the next generation Compton telescope
Wufeng LIU, Xiangman LIU, Shuwen TANG, Zhiyu SUN, Yuhong YU, Wei WANG, Ruofu CHEN, Fang FANG, Junling CHEN, Duo YAN, Yongjie ZHANG, Shitao WANG, Xueheng ZHANG, Ke YUE, Jianwei LU, Bingqian ZHOU, Yixuan ZHAO
Nuclear Techniques    2020, 43 (1): 10203-010203.   DOI: 10.11889/j.0253-3219.2020.hjs.43.010203
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Background

Compared with other energy regions, little research of gamma-ray astronomy in the MeV energy region has been carried out, hence insufficient exploration of astrophysical information is available in the MeV energy region.

Purpose

This study aims to investigate the gamma-ray astronomy of MeV energy region so as to provide reference for the design of the next generation Compton telescope calorimeter.

Methods

A dual-ended readout gamma-ray detector was designed as the elementary detection unit of a calorimeter. The detector was made of a long CsI(Tl) bar with the size of 10 mm×10 mm×80 mm and wrapped by the ESR film. The photodiode (PD), the avalanche photodiode (APD) and the silicon photomultiplier tube (SiPM) were used respectively as photoelectric converters for the detector, and they were tested by using 137Cs source at different positions on the detector.

Results

The results show that the total energy and interaction position of the incident gamma-ray can be determined by reading the signal amplitudes at two ends of the three photoelectric converters. The energy resolution for 662 keV gamma-ray is 5.9% (full width at half maxima, FWHM) and the position resolution is about 5.7 mm (FWHM), which is the best performance obtained in the case of SiPM readout.

Conclusions

The detection unit designed in this paper can meet the performance requirements of the calorimeter of the next generation Compton telescope.

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Research on optimum detection angle and switching point of non-radioactive nuclear ash bucket level meter
Xicheng XIE, Yuanyuan ZHANG, Yajuan GUO, Wanchang LAI
Nuclear Techniques    2019, 42 (10): 100401-100401.   DOI: 10.11889/j.0253-3219.2019.hjs.42.100401
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Background

Material level detection is a very important issue for the automatic control of thermal power. How to monitor the material and powder level has become an urgent problem for the thermal power plant.

Purpose

This study aims to find out the best detection angle and switching point to provide theoretical guidance for instrument development and sensitivity improvement.

Methods

First of all, Monte Carlo simulation was applied to the optimum design of the best detection angle for non-radioactive nuclear ash hopper level meter in the range of 0°~90°. Then the angle between the ash bucket wall and the horizontal plane for the optimum detection angle was determinated. Finally, a complete model of dust hopper and passive nuclear level gauge for electrostatic precipitator (ESP) was established, and the high and low switch points material level were by "second derivative method".

Results

When the angle between the probe and the horizontal line reaches 30°, the maximum energy flux is detected while the angle between the ash bucket wall and the horizontal plane is 61.224°. The absorption dose rate curve of material level meter with different fly ash height at 30° detection angle is obtained.

Conclusions

This study provides theoretical guidance for the development of non-radioactive nuclear ash hopper level meter instrument and improvement of sensitivity in thermal power plants.

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Detector design and performance test for coded camera of large area and high sensitivity
Yan LI, Qiang WANG, Xianchao HUANG, Lei SHUAI, Daquan CAO, Yiwen ZHANG, Yao YANG, Xuanhou HU, Xiuzuo LIANG, Jun WU, Guoqiang ZENG, Zhiming ZHANG
Nuclear Techniques    2020, 43 (5): 50402-050402.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050402
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Background

The traditional gamma camera cannot locate the contaminated area of nuclear accident, and cannot obtain the information of the contaminated area and degree in real time.

Purpose

This study aims to develop a coded aperture gamma camera detector system with large area and high sensitivity.

Methods

A detector module of large area CsI (Tl) crystal array coupled with photomultiplier tube array was proposed. It consisted of 121 CsI (Tl) crystals at the size of 15 mm×15 mm×15 mm, and 2×2 array composed of 4 detector modules was taken as γ camera detector. Multi-channel readout electronics composed of amplification, filter shaping and single-to-differential conversion circuit was independently designed for readout processing of detector signals. Finally, the performance of this detector system was evaluated by experimental tests.

Results

The results indicate that the detector module can achieve the position resolution, and its average energy resolution is 9.4% under the excitation of 662 keV γ-ray.

Conclusions

The detector system can satisfied the design requirements of coded aperture γ camera of high sensitivity in terms of position resolution, energy resolution, uniformity of peak position and detection efficiency.

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Development of a 4π phoswich detector for measuring radioactive inert gases
Dongdong ZHOU, Simei YOU, Jie XIN, Cuiping YANG, Wanxin WEN, Yue YANG, Baoguo ZHANG, Rensheng WANG, Ming ZHANG
Nuclear Techniques    2020, 43 (5): 50401-050401.   DOI: 10.11889/j.0253-3219.2020.hjs.43.050401
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Background

The radiation field of the radioactive inert gas generated in a nuclear power station is mainly β-γ mixed field. The phoswich detector has good ability to discriminate β and γ rays.

Purpose

This study aims to develop a set of 4π phoswich detector to accurately measure the energy spectrum of the mixed field and distinguish β-γ rays.

Methods

The phoswich detector mainly consisted of a hollow cylindrical plastic scintillator EJ-200 with layer thickness of 1 mm and a cesium iodide scintillator CsI (Tl) with side wall thickness of 20 mm overlay on the outer layer of EJ200. The two photomultiplier tubes (PMT) were placed at both end surfaces of the cylinder respectively, and coupled by using silicone oil. The DT5790 dual digital pulse shape analyzer of CAEN company and the digital pulse processing-pulse shape discrimination (DPP-PSD) were used to obtain the detector output signals, and results were processed by ROOT and MATLAB software. Finally the detector was calibrated by use 133Ba and 137Cs radiation sources.

Results & Conclusions

The β-γ signal discrimination is realized by mathematical methods in back end computer software, indicating that the detector is capable of measuring radioactive inert gas.

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Study of the low voltage power module for SiPM
Shiyu YIN, Pengyu CHEN, Lishuang MA, Sen QIAN, Yao ZHU, Feng GAO, Yang WANG, Zhigang WANG, Zhe NING
Nuclear Techniques    2019, 42 (9): 90403-090403.   DOI: 10.11889/j.0253-3219.2019.hjs.42.090403
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Background

Silicon photomultiplier (SiPM) also named multi-pixel photon counter (MPPC) has excellent performance, but it is difficult to carry out large scale testing due to the limitations of the power supply board.

Purpose

This study aims to test the performance of the self-developed voltage-adjustable, batch-programmable SiPM low-voltage power supply module.

Methods

The performance of the new type of SiPM power driver board developed by our laboratory was tested and analyzed by the method of comparative test with commercial power supply. [Results &

Conclusion

The performances of proposed power module are comparable to that of the commercial module, and satisfy the reqiurments of SiPM batch test.

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Progress of single event effects and hardening technology of CMOS image sensors
Yulong CAI, Yudong LI, Lin WEN, Qi GUO
Nuclear Techniques    2020, 43 (1): 10502-010502.   DOI: 10.11889/j.0253-3219.2020.hjs.43.010502
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Background

CMOS imager sensors (CISs) used in the space radiation environments are susceptible to single event effects (SEEs), which can cause images corruption and even CIS function failure.

Purpose

This study aims to evaluate the progress of SEEs and hardening technology of CIS.

Methods

In this paper, the SEEs on the CIS are reviewed by summarizing the investigation from different particles such as heavy ions, protons, electrons and neutrons, and from different types of SEEs: including single event transient (SET), single event upset (SEU), single event functional interrupt (SEFI) and single event latch-up (SEL). Progresses of SEEs hardening technology on CIS are briefly investigated.

Results & Conclusions

This paper analyzes the SEEs and problems to be solved urgently on hardening technology on the CIS technology, which provides theoretical reference for further researches in the future.

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Simultaneous quick measurements of combined synchrotron EDXAFS and EDXRD
LIU Zhijie,LUO Zhenlin
Nuclear Techniques    2019, 42 (12): 8-12.   DOI: 10.11889/j.0253-3219.2019.hjs.42.120102
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Background

X-ray absorption fine structure (XAFS) and X-ray diffraction (XRD) are the commonly used techniques to determine the short-range and long-range order of atomic arrangement in materials.

Purpose

This study aims to perform XAFS and XRD measurements quickly and simultaneously for in situ kinetic structural investigation.

Methods

A method of combining synchrotron energy-dispersive X-ray absorption fine structure (EDXAFS) and energy-dispersive X-ray diffraction (EDXRD) was proposed. The white light of synchrotron radiation was used that could theoretically provide microsecond scale representation speed and time resolution.

Results & Conclusions

With a potential temporal resolution of micron seconds, this strategy provides a possibility for quick and simultaneous characterization of short- and long-range structural information of materials that sheds light on in-situ real-time investigation of structural evolution in materials in real conditions.

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Preparation of amidoxime-based ultra-high molecular weight polyethylene fiber for removing uranium from fluorine-containing wastewater
Xinxin FENG, Long QIU, Mingxing ZHANG, Maojiang ZHANG, Yulong HE, Rong LI, Guozhong WU
Nuclear Techniques    2020, 43 (2): 20301-020301.   DOI: 10.11889/j.0253-3219.2020.hjs.43.020301
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Background

During the uranium enrichment process, the generated wastewater containing fluoride and uranyl ions, has potential threat to aquatic ecosystem and human health. Thus, the uranium concentration in the wastewater and its secondary sources must be reduced to an acceptable value before being discharged into the environment.

Purpose

This study aims to graft acrylonitrile (AN) and methacrylic acid (MAA) onto ultra-high molecular weight polyethylene (UHMWPE) fiber to synthesize amidoxime (AO)-based sorbent for removing uranium (U(VI)) from simulated wastewater containing fluoride ions.

Methods

The AO-based sorbent was prepared by radiation grafting of AN and MAA onto UHMWPE fiber, followed by amidoximation. The chemical structures and surface morphologies of the pristine and modified UHMWPE fiber were characterized by Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The uranium adsorption performance of the sorbent was investigated by batch adsorption in simulated wastewater.

Results and Conclusions

1) The uranium sorption kinetics and isotherm of AO-based UHMWPE fiber were in congruence with the pseudo-second-order model and the Langmuir model, respectively. 2) The maximum U(VI) adsorption capacity in simulated wastewater (U(VI): 40 mg?L-1; sodium fluoride (NaF): 10 g?L-1; sorbent dosage: 0.2 g?L-1; time: 21 d) was 151.98 mg?g-1, which is basically consistent with the theoretical saturated adsorption capacity (153.85 mg?g-1). 3) The removal ratio of U(VI) in simulated wastewater reached 99.93% by increasing sorbent dosage (1.5 g?L-1), and the residual uranium (28 μg?L-1) can meet the national discharge standard (< 50 μg?L-1).

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Experimental study on irradiation damage dose of 180 nm CMOS MCU
Faguo CHEN, Rong GUO, Guodong LI, Runcheng LIANG, Yi HAN, Mingming YANG
Nuclear Techniques    2019, 42 (11): 110401-110401.   DOI: 10.11889/j.0253-3219.2019.hjs.42.110401
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Background

The radiation effects of semiconductor devices include single event upset effect, total ionizing dose effect and dose rate effect. The total ionizing dose effect on electronic systems becomes a priority for the improvement of reliability of radiation-tolerance robots.

Purpose

This study aims to measure the irradiation damage dose of STM32 microcontroller unit fabricated by 180 nm complementary metal oxide semiconductor(CMOS) technology with on-line and off-line experimental testing approaches.

Methods

A test system which consisted of minimum circuits, dosimeter, communication circuit and host computer was developed. On-line and off-line irradiation experiments were performed on 89 samples using 60Co source with different dose rates. Among these samples, 14 samples were on-line irradiated under 63.3 Gy(Si)?h-1 and 101.2 Gy(Si)?h-1 dose rates whilst 75 samples were off-line irradiated under dose rates range of 227.2 Gy(Si)?h-1 to 855.0 Gy(Si)?h-1.

Results

The irradiation damage dose are (235.4±16.4) Gy(Si) and (197.4±13.0) Gy(Si), respectively, corresponding to the on-line testing with 63.3 Gy(Si)?h-1 and 101.2 Gy(Si)?h-1 dose rates. The irradiation damage dose of off-line testing is between 391.5 Gy(Si) and 497.6 Gy(Si).

Conclusions

On chip flash memory is the first damaged hardware unit in STM32 microprocessor, and the tolerant dose limit of off-line test is significantly higher than that of on-line test.

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Influence of 7Li enrichment in FLi/FLiBe on Th-U conversion performancefor molten salt fast reactor
Jun ZHOU, Jingen CHEN, Chenggang YU, Chunyan ZOU
Nuclear Techniques    2019, 42 (11): 110601-110601.   DOI: 10.11889/j.0253-3219.2019.hjs.42.110601
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Background

Lithium is an important component of coolant in liquid molten salt reactor (MSR). The neutron absorption cross section of the isotope 6Li is much larger than that of 7Li. Hence, the content of 6Li in the coolant has an important influence on the Th-U conversion performance for MSR.

Purpose

This paper aims to provide an appropriate reference for the choice of 7Li enrichment in the engineering design of molten salt reactor by studying the influence of 7Li enrichment in FLi/FLiBe on Th-U conversion performance for molten salt fast reactor (MSFR).

Methods

With the help of molten salt reactor reprocessing sequence (MSR-RS), neutron spectrum, 233U inventory, conversion ratio and 233U net production, evolution of Li and tritium production with 7Li enrichment from 99.5% to 99.995% were explored on MSFR with FLi and FLiBe, respectively.

Results

The computation results show that MSFR with FLi has a better Th-U conversion performance than that with FLiBe, and the influence of 7Li enrichment on Th-U conversion performance becomes wake when 7Li enrichment is higher than 99.9%. Compared with the 99.995% 7Li enrichment, the Th-U conversion ratio of 99.9% 7Li enrichment decreases by about 1.6% and the tritium production increases by about 8%.

Conclusions

Considering the cost of enriching 7Li and the Th-U conversion performance, a 99.9% 7Li enrichment is recommended for MSFR with both FLi and FLiBe.

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