Figure of merit for the quality of ZrO2 coatings on stainless steel and nickel-based alloy surfaces

A figure of merit (FOM) has been developed to define the quality of ceramic (e.g., ZrO₂) coatings on metal and alloy [Type 304SS and Alloy 600] surfaces. Zirconia (ZrO₂) coatings were developed as a means of protecting the metal/alloy surfaces from stress corrosion cracking (SCC) in boiling water reactor (BWR) primary heat transport circuits, by inhibiting the cathodic reaction (reduction of oxygen and hydrogen peroxide) on the surface external to the crack. The distribution of pores in the coating plays an important role in corrosion prevention, such that the lower the porosity of the coating, the better the protection afforded to the system against SCC. Since the reactors operate at high temperature (e.g., at 288 °C under full power conditions), the temperature dependence of the FOM was investigated. The figure of merit (FOM) was developed by measuring impedance data over a wide range of frequency (10 mHz-5 kHz) at temperatures of 25, 100, 200, and 288 °C in hydrogenated, buffered solutions, with the hydrogen electrode reaction (HER) being used as a “fast” redox couple. An “equivalent circuit” analog was first developed from the bare surface impedance data and this analog was then employed in a second step to model the pore bottom in defining the pore distribution on the coated surface. A lognormal distribution (LND) of the pores was assumed and the parameters of the LND were determined using a constrained optimization technique to fit the model to the experimental data for the coated surface at different temperatures. The results suggest that, as temperature increases, the coating becomes more porous, making the substrate more susceptible to corrosion cracking. At 288 °C, 87% of the SS and 85% of the Ni-alloy surfaces become porous with the pore radius varying from 0.0001 cm to 0.01 cm.     

Analysis of failed nuclear plant components

Argonne National Laboratory has conducted analyses of failed components from nuclear power- gener-ating stations since 1974. The considerations involved in working with and analyzing radioactive compo-nents are reviewed here, and the decontamination of these components is discussed. Analyses of four failed components from nuclear plants are then described to illustrate the kinds of failures seen in serv-ice. The failures discussed are (1) intergranular stress- corrosion cracking of core spray injection piping in a boiling water reactor, (2) failure of canopy seal welds in adapter tube assemblies in the control rod drive head of a pressurized water reactor, (3) thermal fatigue of a recirculation pump shaft in a boiling water reactor, and (4) failure of pump seal wear rings by nickel leaching in a boiling water reactor. Work supported by Commonwealth Edison Company under ACK 85026.     

Bioleaching of refractory gold ore （ Ⅲ ）——Fluid leaching Jinya refractory gold concentrate by Thiobacillus ferrooxidans

A novel fluidized-bed reactor was designed and installed for bloleaching in a semi-continuous way, by which a process for biuleaching-cyanidation of Jinya refractory gold arsenical concentrate was studied. The arsenic extraction rate reaches 82.5 % after 4-day batch biooxidation of the concentrate under the optimized condition of pH 2.0, ferric ion concentration 6.Sg/L and pulp concentration 10%. And leached rate of gold in the following cyanida.tion is over 90%. The parameters of three series fluidized-bed reactors exhibit stability during the semi-continuous bioleaching of the concentrate.Armmic in the concentrate can be got rid of 91% after 6-day leaching. Even after 4 days, 82% of arsenic extraction rate was still obtained. The recovery rates of gold are 92 % and 87.5 % respectively in cyaniding the above bioleached residues.The results will provide a base for further commercial production of gold development.     

A study of function mechanism of hemxamethyl tetra-amine in gelation process of uranium

The UO2 ceramic microspheres are the most important materials in the spherical fuel elements for high temperature reactor (HTR). A process for preparation of UO2 kernels known as total gelation process of uranium (TGU) was developed as the production process of 10 mW HTR at Tsinghua University. The TGU process is based on the traditional sol-gel process, external gelation process and internal gelation process of uranium (EGU and IGU), which implies that the gelation action is initiated both by ammonia out of the gel particles and hemxamethyl tetra-amine (HMTA) inside the gel particles. The gelation behavior and the properties of uranium microspheres were investigated of the solution with and without HMTA. It is observed that good spherical particles can be obtained without HMTA in the sol, which indicates a more controllable and industrialized route will be set up. Contrasts between this route and the traditional EGU were also listed .     

溶剂热结晶法制备纳米氧化铁的工艺研究

采用溶剂热结晶法制备工艺，以硫酸亚铁（FeSO4）为原料，聚乙二醇为溶剂，NH3H2O为沉淀剂，制备纳米氧化铁。然后利用XRD和SEM等分析手段，对样品进行表征，研究结果如下：当pH由6升高到10时，反应时间由90min可以缩短到30min，氧化铁的晶体形态从粒状逐渐向片状晶过渡，颜色加深：当反应温度由140℃升高到170℃时，反应时间由90min缩短到45min，晶体的平均粒度由50nm增加到800nm，均匀性降低，晶体形态由球晶向针状晶过渡，颜色逐渐变红。在本实验条件下，最佳的pH=7，最佳的水热温度为160℃，最佳的水热时间为60min。     

Research on graphite powders used for HTR-PM fuel elements

Different batches of natural graphite powders and electrographite powders were characterized by impurity, degree of graphitization, particle size distribution, specific surface area, and shape characteristics. The graphite balls consist of proper mix-ratio of natural graphite, electrographite and phenolic resin were manufactured and characterized by thermal conductivity, anisotropy of thermal expansion, crush strength, and drop strength. Results show that some types of graphite powders possess very high purity, degree of graphitization, and sound size distribution and apparent density, which can serve for matrix graphite of HTR-PM. The graphite balls manufactured with reasonable mix-ratio of graphite powders and process method show very good properties. It is indicated that the properties of graphite balls can meet the design criterion of HTR-PM. We can provide a powerful candidate material for the future manufacture of HTR-PM fuel elements.     

乙炔法氯乙烯合成固定床反应器的建模及分析

针对我国广泛应用的乙炔法氯乙烯合成固定床反应器,结合氯乙烯合成的反应动力学、催化剂的失活动力学,同时引入了传热方程,建立了完整的列管式氯乙烯合成固定床反应器的数学模型。将该模型用于工业生产,模拟了传热系数沿管长的变化,列管内反应温度沿管长的变化并与生产数据对比,验证了模型的正确性。最后分析了乙炔空速、冷却水温度对管内温度分布和乙炔转化率的影响。     

核电站堆芯温度场软测量方法研究

核电站堆芯内部温度是反应堆安全运行的重要参数,由于受到测点安装条件的限制,无法直接测量。为解决该问题,在现有压水堆堆芯功率模型的基础上,结合稳态传热热量守恒方程,构建堆芯温度场的计算模型,推算出堆芯内部温度。并通过数值模拟计算结果与堆芯出口实测值的比较,运用数据不确定度作为判断依据,验证了方法的可行性,得到了堆芯内部不同截面的二维温度分布图,为堆芯内部温度的实时监测提供了理论依据。     

高级氧化-IC-曝气工艺处理克林霉素生产废水实例

某药业股份有限公司克林霉素生产废水采用高级氧化-IC-曝气工艺处理,重点介绍了工程的调试启动。工程运行结果表明,出水水质稳定,COD为112mg/L,BOD5为23mg/L,SS为48mg/L,NH3-N为37.1mg/L,TN为49.6mg/L,硫化物为0.72mg/L,急性毒性(以HgCl2毒性当量计)为0.05mg/L,pH为8.22,处理后出水毒性和有机物浓度都大大降低,各项水质指标符合《化学合成类制药工业水污染物排放标准》(GB 21904-2008)的要求。     

750kV高漏抗变压器式分级可控高抗应用研究

针对某地区750kV输变电系统存在运行电压偏高的问题,提出了一种将高漏抗变压器式分级可控高抗SCSR应用于该750kV输变电系统的设计方案;分析了SCSR的工作原理,采用电磁暂态仿真软件建立了系统仿真模型,分别仿真了系统在正常状态和故障状态下SCSR投入时抑制工频过电压和潜供电流及容量调节的效果。仿真结果表明,SCSR可有效降低该750kV输变电系统的稳态运行电压,提高系统稳定性。