Advanced Materials Research Vols. 724-725

Abstract: We report on the characteristics of argon inductively coupled plasma (ICP) for the ITER neutral beam injection system. In argon ICP, it was found by using Langmuir probe that the radial distribution of electronic density (N_e) was uniform while the radial distributions of both electron temperature (kT_e ) and electric potential (V_P) were non-uniform. The former depend on two factors: the variation of N_e was small, and the value of N_e was very large. The latter is owing to the generation and disappearance of the negative ions in the ICP, where the additional dynamic processes produce the instability. In addition, both kT_e and V_P profiles were very similar at the cylinder height H=14 cm, which proves the plasma sheath theory to some extent. Finally, both kT_e and V_P began flatter with the reduction of the cylinder height, which is owing to the decrease of the negative ions in the ICP.

Abstract: Nuclear energy is a carbon-free, clean and efficient energy. It is very important in the progress of human civilization and modern development of the world, however, there are still some problems such as nuclear leak and nuclear waste. In this paper, the worlds nuclear energy utilization and nuclear power plant constructions are reviewed and plans are forecasted. The basic reason of previous nuclear power plant accidents in history is summarized. Taking 2011 Tohuku earthquake-fukushima nuclear power station accident as an example,threats to the nuclear power plant by earthquake are investigated and impacts on social, economic and ecological environment caused by nuclear power station accident are analyzed. This paper drew lessons from previous accidents and put forward a variety of countermeasures which are from both the technical and management aspects. We also appeal people all over the world to respect the nature, enjoy the nature, and to create and enjoy the new civilization of human beings.

Abstract: Since heat exchanger is an important device that can control temperature distribution of the liquid Lead-Bismuth Eutectic (LBE) loop, its proper design makes sure investigations on key technologies of Accelerator Driven Sub-critical System (ADS) can be carried out smoothly. Based on heat transfer theory, a design proposal was presented for the cooler of the multi-functional forced convection LBE loop KYLIN-II that is being developed by FDS team. The cooler is a double-pipe countercurrent heat exchanger cooled by heat transfer oil YD-350L. Numerical analysis based on the commercial software ANSYS FLUENT 14.5 was also performed to validate that design proposal in design case and two different operation cases. Theoretical design parameters agreed well with those of the numerical simulation. Deviations of some important parameters (i.e. temperatures of fluids and overall heat transfer coefficient of the cooler) between theoretical values and numerical simulation results were under 2%. The bulk temperature and film temperature of the oil were lower than 305 °C and 360 °C respectively, which were acceptable for heat transfer oil. All these results indicated that the design proposal in the paper was reasonable and could be applied to the design of KYLIN-II LBE loop.

Abstract: As is well known, the disposal of high level nuclear waste is one of the key issues restricting the sustainable development of nuclear energy in the world. The partitioning and transmutation strategy (P&T) has been considered as an alternative for the disposal of high level nuclear waste in future advanced nuclear fuel cycles. For the transmutation of high level nuclear waste, accelerator driven sub-critical system (ADS) has been regarded as the most feasible choice. In this paper, the main technical characteristics of ADS system are described, the world research status and development trends of ADS are introduced, and ADS study plans in China are discussed.

Abstract: Radioactive wastewater on accident cases is characterized by large quantity and complex quality, so the treatment process must be able to meet the request of large quantity, low energy consumption and mobile processing. The quantity and quality of radioactive wastewater under core melt accident case was estimated. The different characteristics of the radioactive waste treatment technology were compared. The practicable technologies and processes for emergency treatment of radioactive waste was analyzed. The recommended flow chart for emergency radioactive wastewater treatment was given out. Some suggestions were given for the research on the emergency treatment of radioactive wastewater technology.

Abstract: In this paper; technological challenges and commercialization barriers for Proton Exchange Membrane (PEM) fuel cell are presented. Initially, the criteria that must be met by the energy source of the future is presented from the point of view of the authors. Sustainability, high energy content and combustion independence are recognized as the main decisive factor of future fuels, which are all met by hydrogen, consequently the application of fuel cells as combustion free direct energy converters of the future. Fuel cell technology as an alternative to heat engines is discussed in the context of the current status of fuel cells in various applications. Finally, the challenges facing fuel cell technology to replace heat engines from the commercial and research points of view are presented and discussed supported by current trends in the industry. It is concluded that there have been several advancements and breakthrough in materials, manufacturing and fabricating techniques of fuel cells since the eighties, many of these challenges which are associated with cost and durability still exist when compared with the already matured technology of internal combustion engines. Any effort to achieve these goals would be a significant contribution to the technology of the fuel cell.

Abstract: High temperature proton exchange membrane (HT-PEM) fuel cell is considered as one of the most probable fuel cells to be large-scale applied due to characteristics of high efficiency, friendly to environment, low fuel requirement, ease water and heat management, and so on. However, carbon monoxide (CO) content in fuel plays an important role in the performance of HT-PEM fuel cells. Volt-ampere characteristics and AC impedance of HT-PEM fuel cell are tested experimentally in this paper, and effects of CO in fuel on its performance are analyzed. The experimental results show that CO in fuel increases remarkably the Faraday resistance of HT-PEM fuel cell and decreases the electrochemical reaction at anode; the more CO content in fuel is, the less HT-PEM fuel cell performance is; with the increasing cell temperature, the electrochemical reaction on the surface of catalyst at anode is improved and the poisonous effects on the HT-PEM fuel cell are alleviated.

Abstract: Co/CeO₂ catalysts showed good catalytic performances in terms of activity, selectivity and stability for intermediate temperature ethanol steam reforming, while low temperature activity should be improved. Thus, effect of nickel incorporation into Co/CeO₂ catalysts for ethanol steam reforming was investigated on the consideration of high activity for CC bond cleavage at low temperature of nickel, while cobalt may improve yield of hydrogen due to the depression of CH₄ formation. A series of Co-Ni/CeO₂ catalysts were prepared by coprecipitation, characterized by low temperature N₂ adsorption, X-ray diffraction, temperature programmed reduction, and catalytic performance measurement for ethanol steam reforming. The results indicated that 10.0% nickel incorporation into Co/CeO₂ resulted in much better catalytic performances, complete conversion of ethanol into C₁ species and hydrogen yield about 60.0% at 350°C were obtained. Further increase of nickel content decreased catalytic performance. The high performance of the Co₁₀-Ni₁₀/CeO₂ was attributed to enhancement of surface Ce⁴⁺ reduction and fine particles of metal.

Abstract: The hydrolysis reaction of sodium borohydride (NaBH₄) can generate highly pure hydrogen. In this paper, the Co-La-B catalyst is prepared using the simple chemical reduction method. Its catalytic reactivity is studied for different NaBH₄ concentrations, NaOH concentrations, the catalyst amounts and the reacting temperatures. For both NaBH₄ concentration and NaOH concentration, the hydrogen generation rate climbs to the peak when they stay around 8 wt.%. The hydrogen generation rate can also be promoted by increasing the catalyst amount and raising the reacting temperature. Structural characterizations of the catalysts are performed from SEM and XRD photos. The value of activation energy for the hydrogen generation process is calculated to be 42.33 kJ/mol and it compares favorably with some other previously reported values.

Abstract: CuO-decorated core-shell montmorillonite-TiO₂ colloids were prepared and characterized with transmission electron microscope, powder X-ray diffraction analysis, Brunauer-Emmett-Teller analysis and UV-vis spectrua. Meanwhile, their photocatalytic activity for hydrogen evolution from water was explored under UV irradiation using methanol as a sacrificial reagent. The results indicate that they are an efficient photocatalyst with a rate of H₂ evolution of 219 μmol·h^-1·g^-1 which is higher than that of anatase TiO₂ nanoparticles.