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    20 July 2018, Volume 52 Issue 7
    Development of Multi-group Constant Processing Software Ruler
    LIU Ping;WU Xiaofei;LI Songyang;WU Haicheng;WEN Lili;WANG Wenming;ZHANG Huanyu
    2018, 52(7):  1153-1159.  DOI: 10.7538/yzk.2018.52.07.1153
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    The multi-group constant processing software Ruler was developed based on the modern software engineering development standard. The well-proven models and methods for generating multi-group constants were used, including resonance reconstruction, Doppler broadening, thermal scattering processing, group cross section and scattering matrices computing, as well as resonance self-shielding treatment. The Ruler consists of 11 modules, which are the main driver, data input and output module, public mathematics module, system common subroutine module, data mode converting module, resonance reconstruction module, Doppler broadening module, unresolved resonance self-shielding module, thermal data generating module, neutron multi-group constants producing module and WIMS-D format data library preparing module, respectively. The validation of Ruler was done against the multi-group generation and benchmarks. It shows that the computational accuracy of Ruler agrees well with that of the NJOY99 code system, but Ruler is much more advanced in the aspects of the computing speed, the maintainability and the extendibility.

    Development and Validation of Nuclear Data Processing Code NECP-Atlas
    ZU Tiejun;XU Jialong;WU Hongchun;CAO Liangzhi
    2018, 52(7):  1160-1165.  DOI: 10.7538/yzk.2018.52.07.1160
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    A home-developed nuclear data processing code named as NECP-Atlas was described in this paper, which included different code modules for different data procession functions. This code can generate WIMS-D or WIMS-E format multigroup library from evaluated nuclear data file, through reconstruction of resolved resonance cross section and linearization of cross sections, Doppler broadening, calculation of unresolved resonance cross sections, calculation of thermal neutron scattering cross sections, calculation of multigroup cross section, and so on. The NECP-Atlas code was tested against WIMSD library update project (WLUP) benchmark and international criticality safety benchmark evaluation project (ICSBEP). The numerical results show that the NECP-Atlas code can get results comparable with NJOY-2016 code.

    Calculation Method for Subgroup Parameters with Accurate Resonance Interference Treatment
    LI Song;ZHANG Qian*;ZHAO Qiang;LI Peijun
    2018, 52(7):  1166-1173.  DOI: 10.7538/yzk.2018.52.07.1166
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    The traditional subgroup parameters are generated under the assumption that only one resonant nuclide is in the system. However, this assumption is not in accordance with the real condition of fuel pellet which may contain different kinds of nuclides, and the resonance interference effect can’t be consi-dered in this method. To solve this problem, a new calculation method of subgroup parameters was proposed in this paper. The effective cross sections of all resonant nuclides in the fuel were used to make the resonance integral table, and the resonance interference effect was treated during this procedure. The numerical results show that the new subgroup parameters have better accuracy for resonance interference treatment.

    Feasibility Study of Heterogeneous Resonance Integral Table of 238U
    ZHANG Qian;LI Song;ZHAO Qiang;WU Hongchun;ZHUANG Kun
    2018, 52(7):  1174-1180.  DOI: 10.7538/yzk.2018.52.07.1174
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    As the complexity and accuracy requirement increase of neutronics calculation of the next generation reactor, it is necessary to introduce the heterogeneous resonance integral table into the multi-group cross section library replacing the homogeneous resonance integral table. The accuracy of embedded self-shielding calculation using heterogeneous resonance integral tables of 238U prepared in different schemes was analyzed. The results show that the density of the moderator and the concentration of boron are crucial in the practical application of heterogeneous resonance integrals. Based on the analysis results, the current scheme of the 2D heterogeneous resonance integral table was improved by a 4D interpolation table to cover all possible operating conditions of PWR. Numerical results show that the improved heterogeneous resonance integral table enhances the accuracy of resonance calculation and improves the applicability of the multi-group library.

    Shielding Calculation of Jinping Underground Laboratory for Nuclear Astrophysics
    ZHANG Huanyu;LIAN Gang;LIU Ping;REN Jie;RUAN Xichao;WU Qi;TANG Xiaodong
    2018, 52(7):  1181-1185.  DOI: 10.7538/yzk.2018.52.07.1181
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    Jinping Underground Laboratory for Nuclear Astrophysics provides ultra-low background environment for the study of nuclear astrophysics critical reaction. In addition, the use of 400 kV high current and high stability accelerator makes the direct measurement of the interested energy zone in nuclear astrophysics (Gamow window) possible. In order to avoid the damage caused by the background of accelerator to the laboratory’s ultra-low background, it’s necessary to estimate the background of the accelerator and establish the overall shielding system formal. The preliminary design of shielding system was simulated by MCNP method based on the comprehensive evaluation nuclear database CENDL-NP recommended by China Nuclear Data Center. In order to improve the precision of MCNP method in computing deep neutron penetration problem, weight window technique and changing geometric condition were used to reduce the variance. The results of calculation show that the shielding system of the laboratory effectively reduces the background caused by the accelerator.

    Application of Evaluated Nuclear Data in Design of Heat Pipe Cooled Space Reactor
    LI Songyang;WANG Dingqu;JIANG Yueyuan;LI Weihua;GUO Wenli
    2018, 52(7):  1186-1193.  DOI: 10.7538/yzk.2018.52.07.1186
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    Heat pipe cooled space reactor is an important candidate for space reactor power system. The materials applied in space reactor core are quite different to those in PWR core. Taking HP-SMTCs reactor core as an example, materials containing rhenium, molybdenum, lithium and beryllium are widely used. In order to examine the influence of evaluated nuclear data of these isotopes to the nuclear design of heat pipe cooled space reactor, Monte Carlo criticality calculations were done using cross section data from various sources and versions for HP-SMTCs core in different configurations. Neutron data files from ENDF/B series, JEFF and CENDL for rhenium and molybdenum which can stand high temperature environment were discussed. The Monte Carlo calculation results were compared. Sensitivity coefficients were calculated for main isotopes in the core, and finally the demand for evaluated nuclear data in space reactor area was pointed out.

    Study on Critical Effect of Nuclear Fuel Fission Product
    YIN Shenggui;XIA Zhaodong;LIANG Shuhong;ZHU Qingfu;CAO Jian
    2018, 52(7):  1194-1199.  DOI: 10.7538/yzk.2018.52.07.1194
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    Critical experiments on the four fission products including Ag, Sm, Gd and Nd were conducted on uranyl nitrate solution experiment facility. The fissile material of the core was solid-liquid two-phase, solid fuel was uranium dioxide and liquid fuel was uranyl nitrate. The fuel rods were arranged in hexagonal lattice, and were soaked in uranyl nitrate solution. The results of the critical experiment were compared with those of the Monte Carlo code MONK. The theoretical calculation results are in good agreement with the critical experimental results. The negative reactivity worth introduced by the fission product sample is considerable and the spectrum change shows that the absorption of neutrons by the fission product sample plays a conclusive role in the energy region below the thermal energy point.

    Measurement and Analysis of Leakage Neutron Spectrum from Gallium Sample
    HAN Rui;CHEN Zhiqiang;NIE Yangbo;TIAN Guoyu;LUO Fei;SUN Qi;SHI Fudong;ZHANG Suyalatu;SONG Lin;ZHANG Xin;RUAN Xichao;REN Jie
    2018, 52(7):  1200-1205.  DOI: 10.7538/yzk.2017.youxian.0786
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    Based on the neutronics integral experimental setup at China Institute of Atomic Energy, the leakage neutron spectra from gallium samples were measured by time-of-flight technique with a BC501A scintillation detector. For the benchmark analysis of the neutron evaluated nuclear data of gallium, the leakage neutron spectra were simulated by MCNP 4C code with the ENDF/B-Ⅶ.1, JEFF-3.2 and TENDL-2015 evaluated nuclear data libraries and compared with experimental data and TALYS code calculated results. The results show that the measured data are well reproduced by simulation with the TENDL-2015 library below the 9 MeV. The calculation results of JEFF-3.2 and TENDL-2015 libraries give better agreement with the measured data in the elastic scattering energy region. For the inelastic scattering peak around 12 MeV, JEFF-3.2 library shows a better agreement with the measured data, and TALYS results indicate that the contribution of discrete levels is dominated contribution.

    Uncertainty Analysis of Nuclear Data for Th-U and U-Pu Fuel Cycles in Molten Salt Reactor
    HU Jifeng;WANG Xiaohe;WU Jianhui;CAI Xiangzhou;HAN Jianlong;CHEN Jingen
    2018, 52(7):  1206-1213.  DOI: 10.7538/yzk.2018.52.07.1206
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    Uncertainty of reactor physical design is one of the necessary parameters for the QMU (quantification of margins and uncertainties) validation of the Generation-Ⅳ nuclear reactors, and uncertainty of nuclear data is an important source. Using BUND (burnup uncertainty of nuclear data) code to couple TRITON and TSUNAMI-3D modules of SCALE code, calculations of uncertainties for the effective multiplication factor keff in the molten salt reactor for Th-U and U-Pu fuel cycles were performed. The results were compared with the calculation results of uncertainty for keff by the covariance data from ENDF/B-Ⅶ.1. It is found that, at the beginning of life, the uncertainties for keff of Th-U and U-Pu fuel cycles are 0.490% and 0.582%, respectively, and they increase with burnup time. At the end of life, reaction channels 239Pu (nubar), (n,f), (n,γ), 105Rh (n,γ), 135Xe(n,γ) and 234U (n,γ), 143Nd (n,γ), 131,135Xe(n, γ) are significant for keff uncertainties of U-Pu and Th-U fuel cycles.

    First Principle Calculation on Adsorption and Diffusion Behavior of Si Atom on CeO2(111) Surface
    JIA Huiling;REN Baogen;LIU Xuejie;JIA Yankun;LI Mei;WU Jinxiu
    2018, 52(7):  1214-1221.  DOI: 10.7538/yzk.2017.youxian.0693
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    In order to research the microscopic behavior of Si atom adsorbed on CeO2(111) surface, the adsorption, electronic structure and diffusion behavior of Si atom on CeO2(111) surface were studied using the first principle method. The adsorption energy was calculated. The electron states density, charge density distribution, diffusion activation energy of the most and sub-stable adsorption sites of Si atom on the CeO2(111) surface were also calculated. The results show that Si atom is most easily adsorbed on the surface layer of O atoms, in which the O bridge site (Obri) has the strongest adsorption, and the adsorption strength at the O top site (Ot) and the O three-fold site (Oh) is second. Si atom only has a great influence on the structure of the nearest surface of O atoms, which is consistent with the increase of the charge density overlap between the Si atom and its nearest neighbor O atoms. The Si atom most easily diffuses from the Obri site to Oh site while around the Ot site, and the required activation energy for diffusion is 0.849 eV.

    Adsorption Ability of Polyaniline/TiO2 Composite for U(Ⅵ) in Aqueous Solution
    XING Yongguo;ZHANG Zhibin;HUA Rong;JIANG Xiaohui;WANG Youqun;LIU Jinhui
    2018, 52(7):  1222-1230.  DOI: 10.7538/yzk.2018.52.07.1222
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    Polyaniline (PANI)/TiO2 was synthesized via polymerization of aniline on the surface of TiO2 which was prepared by a sol-gel method. And the surface functional groups, thermal stability and surface elemental composition of TiO2, PANI and PANI/TiO2 were characterized by FT-IR, TGA and XPS. Effects of pH, contacting time, initial U(Ⅵ) concentration, temperature on the U(Ⅵ) adsorption were investigated and optimized by static batch experiments. The results of FT-IR, TGA and XPS indicate that PANI/TiO2 composite is successfully prepared. The optimum pH value for U(Ⅵ) adsorption on TiO2, PANI and PANI/TiO2 is 5.0, 4.5 and 5.0, respectively. The adsorption isotherms and kinetics as well as the thermodynamics were studied using various models. The results show that the adsorption processes are fitted well to the Langmuir and pseudo-second order equations. In addition, the monolayer adsorption capacity of TiO2, PANI and PANI/TiO2 is 11.49, 22.41 and 43.29 mg/g, respectively. The adsorption processes of TiO2, PANI and PANI/TiO2 for U(Ⅵ) are spontaneous and endothermic in nature. And, the PANI/TiO2 composite shows excellent reusability, whose adsorption capacity only decreases by 15.4% when it is used at the fifth time.

    Study of Bounding Electron Doppler Broadening Correction with Compton Profile Based on RMC Code
    PAN Qingquan;WANG Kan;LI Hao;SHANG Xiaotong
    2018, 52(7):  1231-1236.  DOI: 10.7538/yzk.2017.youxian.0637
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    The Monte Carlo code RMC has the capacity of neutron-photon-electron coupling calculation and can complete the precise shielding calculation. The Compton scattering simulation was carried out in photon transport process with the photon-atomic library. Through the analysis of the Compton scattering physical principle and the Doppler broadening method, the bounding electron Doppler broadening correction was completed with Compton profile and a selective treatment of free electron and bounding electron was achieved by using RMC code. The radionuclide test was carried out to observe the effect of Doppler broadening spectroscopy, and the correctness of the method is proved. Through the calculation and comparison of a typical pressurized water reactor component, the necessity and correctness of the Doppler broadening correction are verified.

    Research of Neutron Fluence of Neutron Absorber Material
    LIU Dongpeng;XIA Zhaodong*;ZHU Qingfu;LI Xiaohui
    2018, 52(7):  1237-1242.  DOI: 10.7538/yzk.2017.youxian.0639
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    Neutron fluence can be used as an indicator of accelerated irradiation experiments. In order to examine the neutron absorption properties of neutron absorber material by accelerated irradiation, the neutron fluence at different storage time of neutron absorber material was calculated. By studying the initial enrichment and burnup of spent fuel assemblies, spent fuel pool temperature and soluble boron concentration, the envelopment of neutron fluence during the storage in the spent fuel pool was obtained. At the same time, the 10B consumption at different storage time was calculated. The results show that the neutron absorption properties of the material in the storage of 10-60 a don’t change significantly. The results of this paper can support to examine the neutron absorption properties of material.

    Thermal Ageing Embrittlement Behavior of Ni-Cr-Mo-V Steel Weld Metal for Reactor Pressure Vessel
    WANG Chenglong;TONG Zhenfeng;ZHANG Changyi;YANG Xingwang;NING Guangsheng;YANG Wen
    2018, 52(7):  1243-1249.  DOI: 10.7538/yzk.2017.youxian.0730
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    The study of thermal ageing embrittlement of temperature sets of reactor pressure vessel surveillance Ni-Cr-Mo-V steel weld metal was conducted. Weld metal is the weakness of the reactor pressure vessel and its service time gets to 120 430 h (the operating temperature is normalized to 300 ℃). The impact test of the 3 batches of weld surveillance sample indicates that the weld metal is embrittled during thermal ageing. Through the study, significant change is not found in the microstructure and micro-Vickers hardness during thermal ageing, indicating that there is no hardening embrittlement mechanism in the thermal ageing process. The study of impact fracture and Auger electron spectroscopy indicates that the impurity element P segregates to the grain boundaries and lowers their cohesion during the long-term thermal ageing. Therefore, the reactor pressure vessel Ni-Cr-Mo-V steel weld metal occurs non hardening embrittlement which is probably caused by the intergranular segregation of impurity element P during the long-term thermal ageing.

    Visual Experimental Investigation on Characteristic of Confined Bubble Evolution in Narrow Space
    CHEN Deqi;LI Chong;HUANG Yanping;LU Qi;WANG Yanlin;HE Xueqiang
    2018, 52(7):  1250-1255.  DOI: 10.7538/yzk.2017.youxian.0657
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    A visual experimental investigation was carried out to research the characteristics of bubble evolution with natural convection in narrow space. The deionized water was used as working fluid. The experimental section was made by polycarbonate with narrow space size of 2 mm×10 mm×250 mm. To observe the bubble evolution from the bottom of experimental section, the heating section was made by FTO conductive glass. The characteristic curves of bubble growth were depicted with different heat fluxes. The results show that changes of the length and the width of bubbles conform exponential function during bubble growth. The aspect ratios of bubbles fluctuate nearby a constant value at the end of bubble growth. The rate of bubble growth is not linear with the imposed heat flux, which is affected by various parameters. Also, the characteristics of confined bubble coalescence were discussed in this paper.

    Experimental Investigation on Microbubble Emission Boiling on Imbedded Heating Surface
    YANG Kai;TANG Jiguo*;SUN Licheng;XIE Guo;BAO Jingjing;MO Zhengyu
    2018, 52(7):  1256-1261.  DOI: 10.7538/yzk.2017.youxian.0640
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    In order to analyze the effect of relative location of heating surface on microbubble emission boiling (MEB), the subcooled boiling occurred on an imbedded heating surface was experimentally studied, and compared with that on a flush heating surface. At liquid subcooling of 25-50 K, MEB was observed on an imbedded heating surface that lowers tank bottom for 3 mm. The heat flux in MEB reaches 5.55 MW/m2 at liquid subcooling of 50 K. Visualized results indicate that a vapor film forms on the heating surface, and expands and shrinks frequently in regime of MEB occurred on the imbedded heating surface. The increase of liquid subcooling enlarges the period of expansion and shrinkage of the film while has limited effect on its amplitude. Furthermore, the lateral expansion of vapor film in MEB can be limited by the surrounding edge of the imbedded heating surface significantly.

    Study of Gas-liquid Two-phase Flow Pattern in Three-side Heating Narrow Rectangular Channel
    ZHOU Yunlong;CHEN Xu;GUO Xintian;ZHANG Wenchao
    2018, 52(7):  1262-1267.  DOI: 10.7538/yzk.2017.youxian.0689
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    Taking deionized-water as working fluid, the flow pattern transformation process in a three-side heating narrow rectangular channel with a 3 mm×43 mm cross section was studied with visualization experiment. A high speed camera was used to record visualization data. Four main flow patterns, bubble flow, slug flow, stirring flow and gas film plug flow, were observed, and the transformation process of bubble forms inside channels of various flow patterns was recorded in detail. The critical point of the flow pattern transformation was recorded and the flow patterns of three-side heating narrow rectangular channel were drawn. The trend and formation mechanism of the boundary curves of flow pattern transformation in flow pattern map were analyzed. Compared with the existing flow patterns of similar channel size, it shows that the flow pattern transformation process and the trend of some flow pattern transformation curves are very different between the three-side heating flows and the adiabatic air-water flows. Due to the effect of narrow-side heating section, the flow pattern transformation process is also significantly different from that in single-side heating channel. The gas film slug flow does not appear either under the adiabatic or the single-side heating conditions.

    Study on Improved Fractional Order Controller of Steam Generator Water Level
    GUO Dan;XIA Hong*
    2018, 52(7):  1268-1275.  DOI: 10.7538/yzk.2017.youxian.0660
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    The steam generator exists the serious false water level phenomenon in a transient disturbance. The difficulty of controlling water level in the low power increases. In order to study the low power water level control problem of steam generator, a time-varying linear parameter change model was established by using linear parameter change theory. A fractional order controller for the steam generator model was proposed based on this model. According to fractional calculus theory, fractional order PIλDμ was adopted. Oustaloup indirect discretization method was used to realize the fractional order PIλDμ control and the Oustaloup method was improved. The influence of four order parameters of inner-loop and outer-loop and two parameters of the improved method varying on system control performance was studied when the load changed. In different power intervals, the simulation experiments of the improved cascade fractional PIλDμ controller were carried out in the case of the same load change. The analysis result shows that the designed improved cascade fractional PIλDμ controller can resist interference effectively. The four order parameters of inner-loop and outer-loop and two parameters of the improved method varying influence control effect to a certain degree. Adjusting the parameters reasonable can improve the transient characteristics of the system obviously.

    Investigation of Two-phase Reverse Flow in U-tube under Low Mass Quality Condition
    CHU Xi;CHEN Wenzhen;HAO Jianli;ZHANG De
    2018, 52(7):  1276-1281.  DOI: 10.7538/yzk.2017.youxian.0701
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    The two-phase reverse flow phenomenon may occur in the inverted U-tubes of steam generator (SG) for natural circulation. A theoretical model of flow and heat transfer for two-phase flow in U-tubes based on the homogenous flow model was established in this paper. A pressure drop-mass flow curve was derived to investigate the mechanisms of two-phase reverse flow in U-tubes. The effects of inlet mass quality and fluid temperature in secondary side on the reverse flow were also analyzed. Then the theoretical results were verified by the RELAP5/MOD 3.3 codes. The research shows that increasing the SG secondary side pressure may reduce reverse flow phenomenon in U-tubes, and the phenomenon more likely occurs when the inlet mass quality increases.

    Experimental Study on Helium Flow Characteristic in Randomly Packed Pebble Bed
    WU Zhenxing;WU Yingwei*;TANG Simiao;LIU Di;QIU Suizheng;SU Guanghui;TIAN Wenxi
    2018, 52(7):  1282-1287.  DOI: 10.7538/yzk.2017.youxian.0706
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    In the tritium breeding regions of helium cooled solid blanket of fusion reactor, the pressure drop characteristics of helium in packed pebble beds are of great significance to the design of the pump power. Based on the background of the tritium breeding regions, the effects of helium flow rate, particle diameter, and the channel length on the pressure drop characteristics were investigated in packed pebble beds. The test section is a rectangular channel with the size of 20 mm×20 mm×500 mm. Flow rate is within 0.1-0.6 m/s and particle diameter is 0.5, 0.8, 1.0, 1.5, 2.0 mm in this experimental study. The experimental results show that pressure drop is positively correlated with the helium flow rate and channel length of beds, and pressure drop is negatively correlated with particle diameter. Compared with Ergun correlation, the experimental values are higher than the calculated values of Ergun correlation in condition with smaller particle diameters due to the effects of the compressibility. Ergun correlation modified with the compressibility was deduced by the momentum equation. The results show that the calculated values of Ergun correlation modified with the compressibility are in good agreement with the experimental data. This study would provide the data support for the design of the tritium breeding regions and the verification for the numerical simulation.

    Design of Fast Reactor Fuel Assembly Based on Kriging Method
    LI Song;YANG Hongyi;ZHOU Zhiwei;FENG Yuheng
    2018, 52(7):  1288-1293.  DOI: 10.7538/yzk.2017.youxian.0650
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    In order to study the influence of flow and heat transfer on the thermal hydraulic characteristics of fast reactor fuel assemblies, the Kriging method was used to study design parameters of the assemblies. The result shows that the P/D and H/D ranges change gradually in a certain direction towards the origin, when the pressure drop of the assembly increases with constant average outlet temperature. While the P/D and H/D range change is not directional when the average outlet temperature of the assembly increases with constant pressure drop. According to the calculation results, the design parameters of assemblies can be obtained under given input limit conditions, which can provide reference for the selection of fuel assemblies for larger fast reactors in the future.

    Heat Transfer Analysis of In-vessel Melt Retention in Ellipsoidal and Spherical Lower Heads
    LIU Fang;ZHANG Yapei;TIAN Wenxi;SU Guanghui;QIU Suizheng
    2018, 52(7):  1294-1299.  DOI: 10.7538/yzk.2017.youxian.0613
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    In the severe accident, the core melt with high temperature is redistributed in the pressure vessel and exerts a thermal load on the pressure vessel wall, which may lead to the failure of pressure vessel. Based on the Fortran90 language, in-vessel melt retention (IVR) analysis code IVRASA-ELLIP in severe accident of ellipsoidal lower head was developed, which was used to analyze the heat transfer and IVR of the pressure vessel with the ellipsoidal lower head under the severe accident. IVRASA-ELLIP was used to calculate the heat transfer of the VVER-1000, and the results of the wall heat flux, the oxide crust thickness and the wall thickness of the pressure vessel were obtained. The results of heat transfer of AP1000 were obtained through IVRASA code, which were compared with the results of VVER-1000. The results show that with the same initial parameters, the wall heat flux of the ellipsoidal lower head is smaller than that of the spherical lower head, the amount of ablation of the pressure vessel wall with the ellipsoidal lower head is smaller than that with the spherical lower head, and the oxide crust thickness in the pressure vessel with the ellipsoidal lower head is thicker than that with the spherical lower head.

    Development and Validation of Multidimensional Fuel and Coolant Interaction Analysis Code COSMETRIC
    GUO Yuxiang;ZHONG Mingjun;XIONG Jinbiao;ZHANG Liang;LIU Xiaojing
    2018, 52(7):  1300-1307.  DOI: 10.7538/yzk.2017.youxian.0632
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    The fuel-coolant interaction analysis code COSMETRIC was developed based on MCBA-SIMPLE algorithm. The code was validated against the representative test cases of KROTOS facility. Comparison between the simulation and KROTOS37 experiment results shows that the code is competent to simulate the corium melt fragmentation and drastic evaporation of coolant during the premixing phase. The code also proves to be reliable to predict the amplitude of peak pressure and propagation speed of pressure shock in explosion phase through comparison with the KROTOS21 test results. Sensitivity analysis was carried out to further evaluate the influence of the initial void fraction, the dimensionless time scale in the hydrodynamic fragmentation model and the initial fragment size on the magnitude of pressure shock. It is found that lager initial void fraction leads to lower pressure shock and slower propagation speed, while the increased initial fragment size and dimensionless time scale can reduce pressure magnitude but increase the propagation speed.

    Multi-layer Clad and Non-rigid Pellet Mechanical Modeling and Its Application
    DENG Yangbin;HE Yanan;WU Yingwei;TIAN Wenxi;QIU Suizheng;SU Guanghui
    2018, 52(7):  1308-1315.  DOI: 10.7538/yzk.2017.youxian.0611
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    Based on the finite difference method, the mechanical model of multi-layer cylindrical body was established for accident tolerant fuel (ATF). The new model was implemented in FRAPCON 4.0 code to replace the original Fracas model. By the simulation for the same research objective, the characteristics of the new and old models were analyzed and the rationality and advancement of modification were validated. The comparison indicates that most of parameters agree well, demonstrating that the non-rigid fuel assumption is reasonable to some extent for the traditional fuel. However, the old model is over conservative in contact pressure prediction, and the upgraded code provides more reasonable result. Finally, the potential application of the multi-layer mechanical model and the upgraded FRAPCON 4.0 in the fuel behavior analysis was predicted.

    Modeling and Control of Penning Ion Source in Neutron Tube
    QIAO Shuang;FAN Qi;YANG Zhiqing;ZENG Jun;LI Gang*
    2018, 52(7):  1316-1320.  DOI: 10.7538/yzk.2017.youxian.0681
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    Because the ion source current in the neutron tube lags the storage current, the regulation speed and stability of the ion source current are not high enough, and then the stability of neutron yield is affected. Based on the analysis of a large number of experimental data, the mathematical model of the neutron tube ion source was established, and the corresponding control algorithm was designed in this paper. The test results show that the constructed ion source model agrees well with the condition of actual ion source. The improved control algorithm can reduce the time for stabilizing the ion source current and increase the stability of neutron yield.

    Calculation of Equilibrium Orbit in Cyclotron Based on Simplex Method
    ZHOU Kai;SONG Yuntao;DING Kaizhong;GE Jian;WANG Zhong
    2018, 52(7):  1321-1325.  DOI: 10.7538/yzk.2017.youxian.0672
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    A physical problem of cyclotron equilibrium orbit was changed into a mathematical problem of solving the minimum value of the objective function by introducing the objective function which describes the orbit closing degree, and the optimal solution of the objective function was found out by using the simplex method so that the problem of the equilibrium orbit was solved. The method can be used to solve the corresponding equilibrium orbit only if any two of initial energy, initial azimuth, initial radius and initial radial momentum are given.

    Micro-beam and Broad-beam Experimental Research of Multiple-cell Upset in 65 nm Dual-well CMOS SRAM
    LI Lili;WANG Dong;LIU Xiajie;LYU Yonghong;LI Kunfeng;CAI Li;SHI Shuting;HUI Ning;GUO Gang
    2018, 52(7):  1326-1334.  DOI: 10.7538/yzk.2017.youxian.0577
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    The heavy-ion micro-beam experiment and broad-beam experiment were performed in two 65 nm dual-well CMOS static random access memories (SRAMs) in normal incident angle, respectively. Single event upset (SEU) cross section and the main physical mechanisms of multiple-cell upset (MCU) were investigated by combining MCU pattern, position and counts with the memory cell array layout. The results show that the micro-beam spot is small and uniform, which makes sure that the ions do not hit the peripheral circuits. The ratio of MCU caused by NMOS transistor and the total SEU events is up to 32%, which indicates the charge sharing between NMOS transistors can not be ignored, while there’s no MCU caused by PMOS transistor during the tests, which infers that the high density well contact can inhibit the charge sharing between PMOS transistors effectively. Moreover, reducing the spacing between the drain and the N-well/P-well interface can lessen the probability of SEU. While reducing the spacing between the same kind of transistors in a memory cell as well as increasing the spacing between the same kind of transistors of adjacent memory cells can also weaken the charge sharing, which leads to less MCU.

    Research on Influence of Collecting Electrode in Two-dimensional Air-ionization Chamber Dose Detector Based on EGSnrc
    XING Guilai;TAN Chunming;WANG Liqiang
    2018, 52(7):  1335-1340.  DOI: 10.7538/yzk.2017.youxian.0666
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    The collecting electrode is an important part of the two-dimensional air-ionization chamber dose detector, which affects the accuracy of dose measurement. In order to study the influence of collecting electrode on dose measurement, the Monte Carlo program EGSnrc was used for simulation calculation. The simulation involved photons with different energy, different materials (C, Al, Cu) for collecting electrode and different thicknesses of the collecting electrode (5.70 μm). The quantitative analysis based on the simulation was given. The results show that carbon is the best choice for collecting electrode within the process condition. When the copper is the only choice, the thickness of the electrode should be as small as possible and the measurement results need to be corrected.

    Detection Efficiency Calibration of Portable γ Spectrometer for 137Cs and 131I Solution Samples
    YAN Xuekun;ZHANG Yan*;LI Yang;LUO Ming
    2018, 52(7):  1341-1344.  DOI: 10.7538/yzk.2017.youxian.0614
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    The portable γ spectrometer can be used for identification of typical nuclides in the primary coolant and acquiring their activity concentrations in situ. The source-peak efficiency should be calibrated to ascertain the relationship between the net area under the characteristic peak of typical nuclide and its genuine activity concentration in the water sample. The efficiency calibration curve was acquired by measuring the mixed solution of 133Ba, 137Cs and 60Co nuclides, and then 137Cs standard liquid and simulated 131I standard liquid were measured respectively. Test results indicate that the spectrometer can identify typical nuclides 137Cs and 131I, and the measuring relative error of activity concentration is less than 10%, which satisfies the requirement of measurement accuracy and sensitivity for fuel element rupture detection.