Jun 2007, Volume 1 Issue 2
    

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  • Strategic position and development prospects of nuclear energy in China
    SHEN Wenquan
    2007, 1(2): 125-128. https://doi.org/10.1007/s11708-007-0015-9
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    By analyzing the challenges of China s energy supply, an excellent perspective of nuclear power development in the country has been described. Taking into account the near-, mid-, and long-term development requirements, a comprehensive, coordinated and sustainable nuclear power program is proposed. Thus, our national nuclear industry can not only catch up with the world s advanced level in proper time, but also possess enough stamina for sustainability.
  • PWR-FBR with closed fuel cycle for a sustainable nuclear energy supply in China
    XU Mi
    2007, 1(2): 129-134. https://doi.org/10.1007/s11708-007-0016-8
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    From the thermal reactor to the fast reactor and then to the fusion reactor; this is the three-step strategy that has been decided for a sustainable nuclear energy supply in China. As the main thermal reactor type, the commercialized development phase of the pressurized water reactor (PWR) has been stepped up. The development of the fast reactor (FBR) is still in the early stage, marked by China experimental fast reactor (CEFR), which is currently under construction. According to the strategy study on the fast reactor development in China, its engineering development will be divided into three steps: the CEFR with a power of 65 MWt/20 MWe; the China prototype fast reactor (CPFR) with a power of 1 500 MWt/600 MWe; and the China demonstration fast reactor (CDFR) with a power of 2 500 3 750 MWt/1 000 1 500 MWe. With regards to the fuel cycle, a 100 t/a PWR spent fuel reprocessing pilot plant and a 500 kg/ a MOX fabrication plant are under construction. A project involving the construction of an industrial reprocessing plant and an MOX fabrication plant are also under application phase.
  • The summary of researches on ADS in China
    XIA Haihong, ZHAO Zhixiang, LI Jigen, SHI Yongqian, HAN Yinlu, ZHU Shengyun, XU Yongli, GUAN Xialing, CUI Baoqun, FU Shinian
    2007, 1(2): 135-140. https://doi.org/10.1007/s11708-007-0017-7
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    The conceptual study on the accelerator driven system (ADS) that lasted for about five years ended in 1999 in China. As one project of the National Basic Research Program of China (973 Program) in the energy domain, which is sponsored by the China Ministry of Science and Technology (MOST), a five-year-program of fundamental research of ADS physics and related technology was launched in 2000 and passed national review at the end of 2005. The China Institute of Atomic Energy (CIAE), the Institute of High Energy Physics (IHEP), the Institute of Heavy Ion Physics in Peking University (PKU-IHIP) and other institutions jointly carried out the research. The research activities were focused on HPPA physics and technology, reactor physics of external source driven sub-critical assembly, nuclear data base and material study. For HPPA, a high current injector consisting of an ECR ion source, LEBT and an RFQ accelerating structure of 3.5 MeV was built. In reactor physics study, a series of neutron multiplication experimental study has been carried out and still being done. The VENUS facility has been constructed as the basic experimental platform for neutronics study in ADS blanket. It s a zero power sub-critical neutron multiplying assembly driven by external neutron produced by a pulsed neutron generator. The theoretical, experimental and simulation study on nuclear data, material properties and nuclear fuel circulation related to ADS is carrying on to provide the database for ADS system analysis. The main results on ADS related researches will be reported.
  • Studies on advanced water-cooled reactors beyond generation III for power generation
    CHENG Xu
    2007, 1(2): 141-149. https://doi.org/10.1007/s11708-007-0018-6
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    China s ambitious nuclear power program motivates the country s nuclear community to develop advanced reactor concepts beyond generation III to ensure a long-term, stable, and sustainable development of nuclear power. The paper discusses some main criteria for the selection of future water-cooled reactors by considering the specific Chinese situation. Based on the suggested selection criteria, two new types of water-cooled reactors are recommended for future Chinese nuclear power generation. The high conversion pressurized water reactor utilizes the present PWR technology to a large extent. With a conversion ratio of about 0.95, the fuel utilization is increased about 5 times. This significantly improves the sustainability of fuel resources. The supercritical water-cooled reactor has favorable features in economics, sustainability and technology availability. It is a logical extension of the generation III PWR technology in China. The status of international R&D work is reviewed. A new supercritical water-cooled reactor (SCWR) core structure (the mixed reactor core) and a new fuel assembly design (two-rows FA) are proposed. The preliminary analysis using a coupled neutron-physics/thermal-hydraulics method is carried out. It shows good feasibility for the new design proposal.
  • China ADS sub-critical experimental assembly—Venus-1 and preliminary experiment
    SHI Yongqian, XIA Pu, LUO Zhanglin, ZHAO Zhixiang, DING Dazhao, ZHU Qinfu, XIA Haihong, LI Jigen, ZHANG Wei, CAO Jian, QUAN Yanhui, LUO Huangda, WU Xiaofei
    2007, 1(2): 150-157. https://doi.org/10.1007/s11708-007-0019-5
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    China s accelerator-driven sub-critical system (ADS) sub-critical experimental assembly Venus-1 and the preliminary experiment is presented. The core of Venus-1 is a coupled one of a fast neutron zone and a thermal neutron zone. The fast neutron zone is at the centre of the core and formed by natural uranium fuel. A fast neutron spectrum field can be produced in the fast neutron zone and used for the transmutation of minor actinides (MAs). The thermal neutron zone surrounds the fast neutron zone and is formed by low-enriched uranium fuel. It is a fission zone. An epithermal neutron zone between the fast neutron zone and the thermal neutron zone can be established for the transmutation of long-lived fission products (LLFP). On July 18, 2005, the first fuel element was loaded into the Venus-1 sub-critical assembly and some preliminary experiments about the sub-critical neutronics were performed. The Venus-1 can be driven by an Am-Be source or other steady neutron source (Cf-252, D-D reaction and D-T reaction) to study the effect of the external neutron source with different energies or a D-T pulsed neutron source on the dynamic characteristics.
  • Transmission probability method based on triangle meshes for solving the unstructured geometry neutron transport problem
    WU Hongchun, LIU Pingping, ZHOU Yongqiang, CAO Liangzhi
    2007, 1(2): 158-166. https://doi.org/10.1007/s11708-007-0020-z
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    The fuel assembly or core with unstructured geometry is frequently used in the advanced reactor. To calculate the fuel assembly, the transmission probability method (TPM) is widely used. However, the rectangular or hexagonal meshes are mainly used in the TPM codes for the normal core structure. The triangle meshes are most useful for expressing the complicated unstructured geometry. Even though the finite element method and Monte-Carlo method are well suited for solving the unstructured geometry problem, they are very time-consuming. Therefore, a TPM code based on the triangle meshes is developed here. This code was applied to the hybrid fuel geometry, and compared with the results of the MCNP code and other codes. The results of the comparison were consistent with each other. The TPM with triangle meshes can thus be applied to the two-dimensional arbitrary fuel assembly.
  • Natural convection heat transfer of water in a horizontal circular gap
    SU Guanghui, WU Yingwei, Kenichiro Sugiyama
    2007, 1(2): 167-173. https://doi.org/10.1007/s11708-007-0021-y
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    An experimental study on the natural convection heat transfer on a horizontal downward facing heated surface in a water gap was carried out under atmospheric pressure conditions. A total of 700 experimental data points were correlated using Rayleigh versus Nusselt number in various forms, based on different independent variables. The effects of different characteristic lengths and film temperatures were discussed. The results show that the buoyancy force acts as a resistance force for natural convection heat transfer on a downward facing horizontal heated surface in a confined space. For the estimation of the natural convection heat transfer under the present conditions, empirical correlations in which Nusselt number is expressed as a function of the Rayleigh number, or both Rayleigh and Prandtl numbers, may be used. When it is accurately predicted, the Nusselt number is expressed as a function of the Rayleigh and Prandtl numbers, as well as the gap width-to-heated surface diameter ratio; and uses the temperature difference between the heated surface and the ambient fluid in the definition of Rayleigh number. The characteristic length is the gap size and the film temperature is the average fluid temperature.
  • Estimation of thermodynamic properties of the ternary molten salt system, LiF-NaF-BeF2, by the modified Peng-Robinson equation
    ZHANG Dalin, QIU Suizheng, SU Guanghui, JIA Dounan
    2007, 1(2): 174-180. https://doi.org/10.1007/s11708-007-0022-x
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    The molten salt reactor (MSR), which is one of the generation IV reactors, can meet the demand of transmutation and breeding. The thermodynamic properties of the molten salt system like LiF-NaF-BeF2 influence the design and construction of the fuel salt and coolant in the MSR for the new generation. In this paper, the equation of state of the ternary system 15%LiF-58%NaF-27%BeF2, over the temperature range from 873.15 to 1 073.15 K at one atmosphere pressure, is described using a modified Peng-Robinson (PR) equation. The densities of the ternary system and its components are estimated by this equation directly, and compared with the experimental data. Based on the equation of state, the other thermodynamic properties such as the enthalpy, entropy and heat capacity at constant pressure are estimated by the residual function method and the fugacity coefficient method respectively. The densities calculated by PR equation are highly in agreement with the experimental data, and the enthalpy, entropy and heat capacity evaluated by the two different methods are consistent with each other. It can be concluded that the modified PR equation can be applied to evaluate the density of the molten salt system, and it is recommended that it be used as the basis to estimate the enthalpy, entropy and heat capacity of the molten salt system.
  • Study on rigid-flexible coupling dynamics of hub-plate system
    ZHAO Feiyun, XIE Yongcheng, ZHANG Ming, HE Yinbiao
    2007, 1(2): 181-188. https://doi.org/10.1007/s11708-007-0023-9
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    Dynamic modeling of a rotating flexible hub-plate system is investigated by using Jourdain s variation principle in which the finite element method (FEM) is used as discretization method for a flexible plate. Different from the previous modeling of a plate with a prescribed large overall motion, the coupling between large overall motion of the system and elastic deformation of the flexible plate is taken into account in the proposed coupling model. The quadratic terms are included in the strain-displacement expression, such that the dynamic stiffening terms are included. Simulation of a rotating hub-plate system indicates that the linear model based on linear strain-displacement assumption may lead to erroneous results in the case of high rotation speed. Conservation of energy verifies the validity of the proposed model. Furthermore, frequency analysis of a hub-plate system shows the difference between the frequencies of the system with free and prescribed large overall motion, and parameter analysis of the system reveals the coupling characteristics of the rotational motion and the deformation.
  • Development of a steady thermal-hydraulic analysis code for the China Advanced Research Reactor
    TIAN Wenxi, QIU Suizheng, GUO Yun, SU Guanghui, JIA Dounan, LIU Tiancai, ZHANG Jianwei
    2007, 1(2): 189-194. https://doi.org/10.1007/s00000-007-0024-8
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    A multi-channel model steady-state thermal-hydraulic analysis code was developed for the China Advanced Research Reactor (CARR). By simulating the whole reactor core, the detailed mass flow distribution in the core was obtained. The result shows that structure size plays the most important role in mass flow distribution, and the influence of core power could be neglected under single-phase flow. The temperature field of the fuel element under unsymmetrical cooling condition was also obtained, which is necessary for further study such as stress analysis, etc. of the fuel element. At the same time, considering the hot channel effect including engineering factor and nuclear factor, calculation of the mean and hot channel was carried out and it is proved that all thermal-hydraulic parameters satisfy the Safety design regulation of CARR .
  • Development and application of a random walk model of atmospheric diffusion in the emergency response of nuclear accidents
    CHI Bing, LI Hong, FANG Dong
    2007, 1(2): 195-201. https://doi.org/10.1007/s11708-007-0025-7
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    Plume concentration prediction is one of the main contents of radioactive consequence assessment for early emergency response to nuclear accidents. Random characteristics of atmospheric diffusion itself was described, a random walk model of atmospheric diffusion (Random Walk) was introduced and compared with the Lagrangian puff model (RIMPUFF) in the nuclear emergency decision support system (RODOS) developed by the European Community for verification. The results show the concentrations calculated by the two models are quite close except that the plume area calculated by Random Walk is a little smaller than that by RIMPUFF. The random walk model for atmospheric diffusion can simulate the atmospheric diffusion in case of nuclear accidents, and provide more actual information for early emergency and consequence assessment as one of the atmospheric diffusion module of the nuclear emergency decision support system.
  • Numerical simulation of sudden-expansion two-phase flows with two-scale second-order moment particle turbulence model
    ZENG Zhuoxiong, HAN Shoulei, ZHOU Lixing
    2007, 1(2): 202-206. https://doi.org/10.1007/s11708-007-0026-6
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    A two-scale second-order moment particle turbulence model is developed, based on the concept of particle large-scale fluctuation due to turbulence and particle small-scale fluctuation due to collision. The model is employed to simulate gas-particle flows in a sudden-expansion chamber. Simulation results are compared with the experimental results and with those obtained by the single-scale second-order moment two-phase turbulence model. It is shown that the two-scale model is with higher calculating accuracy than the single-scale model.
  • Investigations on multicycle spray detonations
    LI Mu, YAN Chuanjun, ZHENG Longxi, WANG Zhiwu, QIU Hua
    2007, 1(2): 207-212. https://doi.org/10.1007/s00000-007-0027-5
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    Experimental investigations were carried out on a 50-I.D. multicycle pulse detonation engine (PDE) model, and liquid fuel (gasoline) was used. The average of pressure peak, as measured by piezoelectricity pressure transducer, increased versus distance to thrust wall before fully-developed detonation came into being. According to the pressure history, the pressure in detonation tube would not rise abruptly until the flame front advanced a certain distance downstream the spark. Just at that moment, two compression waves spreading to opposite direction were formed. One was enforced by combustion and became detonation rapidly. The other was weakened because of obstacles and insufficiency of fuel. Two methods were used to determine the induction length of two-phase detonation wave through the pressure history. Ignition delay time was found to be longer than deflagration-to-detonation transition (DDT) time, and the sum of the two would change little as cycle frequency increased. So they could be the most important factors controlling two-phase PDE frequency. Filling process and blowdown process were also analyzed.
  • Influence of mineral transformation on emission of particulate matters during coal combustion
    LIU Xiaowei, XU Minghou, YU Dunxi, GAO Xiangpeng, CAO Qian, HAO Wei
    2007, 1(2): 213-217. https://doi.org/10.1007/s00000-007-0028-4
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    Combustion of pulverized coal was studied in a drop tube furnace to understand coal mineral properties with the emission of particulate matters (PM). Experimental conditions were selected as follows: coal particle size was smaller than 63 μm; reaction temperature was 1 100vH, 1 250vH and 1 400vH respectively; oxygen content was 20% and 50% respectively. PM was collected with a 13-stagelow pressure impactor (LPI) having an aerodynamic cut-off diameter ranging from 10.0 μm to 0.03 μm for a size-segregated collection. Such properties as concentration, particle size distribution and elemental composition of PM were investigated. The experimental results indicate that the emitted PM has a bimodal distribution having two peaks around 4.0 μm and 0.1 μm. Increasing temperature leads to the formation of more PM; varied oxygen content leads to much change of emitted PM. PM was also subjected to XRF analysis to quantify the elemental composition. The results show that PM of 0.1 μm is rich in sulfates. Meanwhile, SiO2 and Al2O3 are prevalent in PM of 4.0 μm, which means that the last peak around 4.0 μm is mainly aluminosilicate salts.
  • Application of digital holography to circle flow bed boiler measurement
    PU Shiliang, WANG Qinghui, CEN Kefa, Denis Lebrun, REN Kuanfang
    2007, 1(2): 218-222. https://doi.org/10.1007/s11708-007-0029-3
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    The spatial distribution of particles in the boiler is very important in the study on the circle flow bed boiler (CFB). Digital in-line holography technique was applied to obtain the spatial and diameter distribution of the particles inside the boiler. A HE-NE laser was used to illuminate the particles inside the CFB through two glass windows and the in-line diffraction pattern was recorded by a CCD camera. The diffraction can be interpreted as a convolution between a family of wavelet functions and the object function. So the three-dimensional (3D) images of the particles in the two-phase flow were reconstructed by the convolution between diffraction pattern and wavelet functions. The particle diameters and 3D coordinates were calculated from the reconstructed 3D images by a series of image-processing methods, followed by a discussion of the experimental results.
  • Emergy evaluation of polygeneration systems
    WANG Lingmei, LI Zheng, NI Weidou
    2007, 1(2): 223-227. https://doi.org/10.1007/s00000-007-0030-x
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    To expand the application range of the emergy evaluation method, an emergy evaluation index, which can reflect the particular feature of polygeneration systems, has been elaborated on the basis of energy and emergy conservation, guided by the fundamental principle of emergy analysis. With this index, the cost structure, emission effect and energy saved were all considered on the same level of importance. To exemplify, some power polygeneration systems (methanol-power generation, hydrogen-power generation) are considered using coal as the basic fuel. The results showed that emergy evaluation indices are practical for comprehensively evaluating polygeneration systems and their sustainability, which is influenced by such factors as the joining mode of polygeneration and the technologies used. The sustainability of polygeneration systems, which work on an appropriate ratio of fuel-to-electric power basis, is higher than that of singular production systems.
  • Nitrous oxide formation and emission in selective non-catalytic reduction process
    YANG Weijuan, ZHOU Junhu, ZHOU Zhijun, CEN Kefa
    2007, 1(2): 228-232. https://doi.org/10.1007/s11708-007-0031-9
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    Pulverized coal-fired boilers are not nitrous oxide sources because of high temperature combustion. But selective non-catalytic reduction may produce N2O by NO reduction reactions. Chemical kinetics calculation and experimental research were used to find out the mechanism between N2O and N-agent species, N-agent/NO nitrogen stoichiometric ratio (NSR), reaction temperature, reaction time, etc. The results show that N2O emission decreases with increasing reaction temperature and NSR decreases when reaction time is enough. N2O concentration first increases then decreases as SNCR reactions keep on occuring. Ammonia SNCR tests indicated that N2O emission was 0 7 μmol/mol. About 8.7% of NO was transformed to N2O, and N2O emission was 27.8 μmol/mol at urea-SNCR test. Urea-SNCR is likely to bring N2O emission problem.
  • Numerical simulation of laminar premixed combustion in a porous burner
    ZHAO Pinghui, CHEN Yiliang, LIU Minghou, DING Min, ZHANG Genxuan
    2007, 1(2): 233-238. https://doi.org/10.1007/s11708-007-0032-8
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    Premixed combustion in porous media differs substantially from combustion in free space. The interphase heat transfer between a gas mixture and a porous medium becomes dominant in the premixed combustion process. In this paper, the premixed combustion of CH0/air mixture in a porous medium is numerically simulated with a laminar combustion model. Radiative heat transfer in solids and convective heat transfer between the gas and the solid is especially studied. A smaller detailed reaction mechanism is also used and the results can show good prediction for many combustion phenomena.
  • Combustion characteristics of a direct-injection diesel engine fueled with Fischer-Tropsch diesel
    HUANG Yongcheng, ZHOU Longbao, PAN Keyu
    2007, 1(2): 239-244. https://doi.org/10.1007/s11708-007-0033-7
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    Fischer-Tropsch (F-T) diesel fuel is characterized by a high cetane number, a near-zero sulphur content and a very low aromatic level. On the basis of the recorded incylinder pressures and injector needle lifts, the combustion characteristics of an unmodified single-cylinder direct-injection diesel engine operating on F-T diesel fuel are analyzed and compared with those of conventional diesel fuel operation. The results show that F-T diesel fuel exhibits a slightly longer injection delay and injection duration, an average of 18.7% shorter ignition delay, and a comparable total combustion duration when compared to those of conventional diesel fuel. Meanwhile, F-T diesel fuel displays an average of 26.8% lower peak value of premixed burning rate and a higher peak value of diffusive burning rate. In addition, the F-T diesel engine has a slightly lower peak combustion pressure, a far lower rate of pressure rise, and a lower mechanical load and combustion noise than the conventional diesel engine. The brake specific fuel consumption is lower and the effective thermal efficiency is higher for F-T diesel fuel operation.
  • Modification of premixed combustion in shear layers by grid turbulence
    MU Kejin, WANG Yue, ZHANG Zhedian, NIE Chaoqun
    2007, 1(2): 245-250. https://doi.org/10.1007/s11708-007-0034-6
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    The influence of grid turbulence on the shear layer of a jet and the premixed flames embedded in it was investigated in the present study. The velocity field of the jet was measured by using hot-wire anemometry. It was found that grid turbulence reduced turbulence intensities in the shear layer and suppressed low frequency fluctuation. Moreover, the energy contained in small-scale fluctuation was increased and turbulence became homogeneous. The results indicate that grid turbulence inhibits the formation of a large-scale coherent structure in the shear layer. Flame temperature was measured by using a compensated fine-wire thermocouple. It was found that grid turbulence reduced low frequency fluctuation of the flame fronts, increased the small-scale wrinkles and elevated the mean temperature of the flame zone. The results show that grid turbulence can enhance and stabilize premixed flames in shear flow.