大功率离子源负载端数据采集系统研制

大功率离子源是整个中性束注入装置的核心部件。离子源灯丝、弧等关键部件的运行状态对系统实验参数设定、故障判断至关重要。为了实时监控灯丝、弧的运行状态,设计了一款大功率离子源负载端数据采集系统。系统采用伏频(V/F)转换技术实现了采样信号的远程隔离传输。PXI系统和Lab VIEW将采样信号进行实时显示。实验结果表明,在直流和调制注入模式下,系统实现了离子源灯丝和弧电压的远程实时监控。     

Study on the Hydrogenated Diamond-Like Carbon Films Synthesized by RF-PECVD from n-decane

Using a mixture of n-decane and hydrogen, diamond-like carbon thin films (DLCTFs) with high growth rate of 35?nm/min are deposited by radio frequency plasma enhanced chemical vapor deposition. We show that n-decane can be considered as a promising carbon source in DLCTF deposition. The properties of the deposited films such as structure, hydrogen content, deposition rate and refractive index are studied for 20, 50 and 100?sccm hydrogen flow rates (HFRs). It is shown that the deposition rate has a maximum of 35?nm/min for HFR?=?20?sccm and by increasing hydrogen concentration, deposition rate drops to 19?nm/min for HFR?=?100?sccm. The Raman spectra reveal that the films represent hydrogenated diamond-like carbon features. The photoluminescence background of the Raman spectra is used as a measure for hydrogen content of the films. The hydrogen content varies from 29 to 46% which yields a various amount of sp³ fraction. The results of the spectroscopic ellipsometry indicate that by increasing HFR, refractive index decreases from 2.1 to 1.9 at 632?nm. The aforementioned trends are attributed to the increase of hydrogen content in DLCTFs which is in very good agreement with enhancing of the photoluminescence background of the Raman spectra.     

Removal and Recovery of Uranium using Microorganisms Isolated from Japanese Uranium Deposits

Attempts were made to remove and to recover uranium present in nuclear fuel effluents and mine tailings using microorganisms isolated from a Japanese uranium mine. Hundreds strains of microorganisms were screened to establish which microorganisms removed the most uranium. Of the tested microorganism strains, an extremely high uranium removing ability was found in some bacteria, including Lactobacillus sp., which can remove about 2,200 μmol uranium per gram dry wt. of microbial cells within one hour. These microbial cells can remove uranium from the uranium refining wastewater with a high efficiency. Lactobacillus cells can remove more uranium from seawater than the other microorganisms which have superior uranium removing capacities from non-saline uranium solutions. The Lactobacillus cells immobilized with a polyacrylamide gel have excellent handling characteristics and can be repeatedly used in the adsorption-desorption cycles. The Lactobacillus cells can be used as an adsorbing agent for the removal and recovery of uranium present in nuclear fuel effluents, mine tailings, seawater, and other waste sources.     

Influence of Nitrogen on Hydrogenated Amorphous Carbon Thin Films Deposited by Plasma Focus Device

To carry out our research, a plasma focus device is used to deposit thin films of nitrogen doped hydrogenated amorphous carbon (a-C:H:N) onto the stainless steel-AISI-304 substrates at room temperature. Thin films are deposited with the same numbers of focus shots, at the same distance from the anode tip and with different partial pressures of nitrogen in the mixtures of acetylene/nitrogen as working gas. The nitrogen contents of deposited films are studied using nuclear reaction analysis (NRA) techniques. The results prove that nitrogen contents of the samples do not increase significantly by increasing partial pressure of nitrogen of the working gas for both sets of the samples. Moreover, NRA results exhibit the limitation of nitrogen incorporated into the samples, when this experimental setup is used. G-peak position and peak intensity ratio of the D-band to G-band (I_D/I_G) are used to investigate the diamond characters. Also, they show that sp² clustering is highly dependent on the nitrogen atomic contents and angular position of the samples. Scanning electron microscopy (SEM) shows the granular surface morphology of the films. Furthermore, it shows that angular position of the samples with respect to the anode axis plays an important role in the grain size of the surface of the samples. The thickness of the films decreases significantly by increasing angular position of the samples, while it decreases slightly by increasing partial pressure of nitrogen of the working gas. The Vickers surface hardness of the thin films exhibits significant dependency on the sp² clustering.     

放射源远程遥控搜寻系统的设计及实验验证

设计了由辐射剂量仪、遥控机器人和手机或信号无线发送接收器等构成的远程遥控搜寻丢失放射源的机器人系统。采取两种方法(手机QQ视频和信号无线发送与接收)实现剂量仪数据和机器人坐标位置的远程无线实时获取。根据放射源辐射场分布规律,建立了辐射场剂量率分布数据库;设计了简单易行的机器人行走路线,快速获取9点剂量率数据;通过比较数据之间的关系和查询数据库确定放射源的具体位置,从而快速找到丢失的放射源,大大降低放射源对搜寻人员的辐射伤害,遥控距离达30 m,辐射剂量降低900倍。     

Method for Using Measurements of the Contamination of Bottom Deposits to Estimate the Source of Radioactive Substances Flowing into a River

A method of estimating the strength of a stationary source of radioactive substances entering a river is proposed. The method is based on statistically reliable measurements of the concentration of radionuclides in bottom deposits. The stationary model of the transport of a radioactive impurity in a two-dimensionally uniform flow is used to determine a relation between the concentration of radionuclides in bottom deposits and the strength of the source. The model is based on the two-dimensional equation for turbulent diffusion and takes account of the interaction of radioactive substances between the water mass (solution, suspension) and bottom deposits. The source of ⁶⁰Co entering the Don River with contaminated underground waters as a result of an incident, which occurred in 1985, in a storage site for liquid wastes from the Novovoronezh nuclear power plant is examined as an example. The average yearly inflow of the radionuclide is estimated to be ∼1·10¹⁰ Bq/yr, which is several times less than the estimates made by experts. __________ Translated from Atomnaya Energiya, Vol. 99, No. 3, pp. 221–228, September, 2005.     

一种确定活性炭滤盒源中碘活度分布的方法

I-131是一种重要的人工放射性核素,是核设施的重要检测对象。目前主要利用均匀分布的Ba-133源代替碘源对I-131的检测仪器进行校准。但在量值传递过程中,I-131校准标准源的分布情况直接影响标准源的定值,对检测仪器的校准产生影响。利用平面源确定不同深度的探测效率,建立效率深度曲线,拟合结果为η(x)=0.007 655e^{-0.020 6x}。由此通过数学分析建立I-131的活度效率方程,利用正反测量结果进行求解,确定其活度分布情况。三个待测I-131源的分布情况为均匀分布、指数分布以及平面分布,均匀分布的源正反测量结果偏差不超过1%,平面分布的源正反测量结果偏差大于50%,指数分布源的偏差介于两者之间。结果表明,通过源分布的快速求解判断,便于校准标准源的准确制备以及现场校准流程的建立。     

Reaction of Recoil Tritium Atoms in a Mixture of Carbon Tetrachloride and Aliphatic Acids

Yields of products from neutron irradiation of a mixture of carbon tetrachloride as additive and aliphatic acids containing lithium chloride have been investigated. In each system, the major products were HT, T-labeled aliphatic acid and T-labeled hydrocarbons. The yield resulting from the abstraction reaction of hydrogen atoms bonded to carbon atoms was affected by the concentration of the additive and depended on the C-H bond strength. On the other hand, the substitution reaction of recoil tritium was not influenced by the concentration of additive. The yield of degradated products from the mixture was smaller than from the irradiation of pure acid. This may be interpreted to be the result of dimer formation in a non-polar solvent.     

A Source for Multiply-Charged Ions and Acceleration of C, N and O Ions by IPCR Cyclotron

The design and performance of the ion source which is now used in the IPCR variable energy cyclotron are described. The source is of the electron-bombarded hot cathode type having two cylindrical cathodes of tungsten and a water-cooled copper anode containing a replaceable molybdenum slit plate. The arc discharge is established continuously but not pulsed. The source is usually operated very stably under an arc power of 1.5 to 3kW with a gas flow rate of 1 to 2 cc/min. The lifetime of the source is mainly limited by the erosion of the upper tungsten cathode at about 24 hours. At present, C4+, N4+, O4+, N5+ and O5+ ions are accelerated up to 48~100, 56~1100, 70~95, 56~125 and 70~125 MeV respectively, and a few micro-amperes of these ions are extracted from the cyclotron. The vacuum obtainable in the accelerating chamber is usually 2 ~ 4 × 10-6 mHg, and the loss of ion beam by the charge exchange effect is comparatively small. Extracted ion beams are used in several experiments for about 1900 hours in a year.     

Influence of Microwave Power on the Properties of Hydrogenated Diamond-Like Carbon Films Prepared by ECR Plasma Enhanced DC Magnetron Sputtering

Electron cyclotron resonance (ECR) plasma was applied to enhance the direct current magnetron sputtering to prepare hydrogenated diamond-like carbon (H-DLC) films. For different microwave powers, both argon and hydrogen gas are introduced separately as the ECR working gas to investigate the influence of microwave power on the microstructure and electrical property of the H-DLC films deposited on P-type silicon substrates. A series of characterization methods including the Raman spectrum and atomic force microscopy are used. Results show that, within a certain range, the increase in microwave power affects the properties of the thin films, namely the sp3 ratio, the hardness, the nanoparticle size and the resistivity all increase while the roughness decreases with the increase in microwave power. The maximum of resistivity amounts to 1.1×109 Ωcm. At the same time it is found that the influence of microwave power on the properties of H-DLC films is more pronounced when argon gas is applied as the ECR working gas, compared to hydrogen gas.     

用碳纳米管从硝酸溶液中回收镅

研究了用碳纳米管从放射性废硝酸溶液中进行镅的回收。在浓硝酸溶液中,碳纳米管对镅的吸附率小于1％;随着硝酸浓度的降低,镅的吸附率迅速升高,当溶液的pH值大于5时,碳纳米管对镅的吸附率达到99.95％以上。用1．5mol／L硝酸进行解吸,一次解吸能够从碳纳米管回收99％以上的镅。     

聚酰亚胺中空纤维膜对CO_2、O_2、H_2O和Xe的分离性能

为了富集环境中的氙,使用中空纤维膜对气体进行预处理,去除掉大量的杂质气体,如氮气、氧气、二氧化碳和水蒸气,氙得以浓缩。为此,建立了膜分离实验装置,实验研究了不同的温度、流量、级切、膜数量、连接方式、气源压力等条件下聚酰亚胺中空纤维膜富集氙并去除CO_2、H_2O和O_2等杂质气体的性能。实验结果表明,气体流量和环境温度对膜的分离性能没有明显影响,采用3根或4根膜串联的方式时氙的损失率较小;在级切为2/3时,氙的损失率不大于10%,CO_2、H_2O和O_2的去除率分别不低于99%、90%和90%;空气样品氙的损失率略大于地表下气体样品。     

余热排出系统安全壳外破口事故源项分析

当余热排出(RHR)系统入口管道在安全壳贯穿件下游发生断裂时,放射性核素随一回路冷却剂的排放直接释放到环境中。本文根据RHR系统安全壳外破口事故的特点,提出了一套评估放射性后果的计算方法。同时,评估了在不同的RHR系统隔离时间下的放射性后果。根据计算结果和GB 6249—2011的要求,选择300s作为发生该类事故后隔离RHR系统的限值,为我国自主化第三代核电厂RHR系统隔离方案设计提供一个设计基准。     

偕胺肟基改性碳纳米管对铀的吸附性能研究

对多壁碳纳米管（MWNTs）进行偕胺肟基改性,采用透射电子显微镜（TEM）和傅里叶变换红外光谱仪（FTIR）进行表征,研究了改性前后MWNTs在不同条件下对铀的吸附性能。结果表明,在pH=2～8的范围内,未改性的碳纳米管（raw-MWNTs）与偕胺肟基改性碳纳米管（AO-MWNTs）对铀的吸附容量均是先增大后降低,pH值为5时达到最大。随着铀初始浓度的增大,raw-MWNTs和AO-MWNTs对铀的吸附容量逐渐升高。当铀初始浓度为10 mg/L时,AO-MWNTs对铀振荡吸附30 min后达到平衡,吸附容量可达18.93 mg/g,而raw-MWNTs对铀振荡吸附60 min后趋于稳定,吸附容量可达9.59 mg/g。AO-MWNTs对铀的吸附符合Langmuir和Freundlich模型,最大理论吸附容量为106.38 mg/g。     

Optical Characterization of Amorphous Hydrogenated Carbon(a-C:H)Thin Films Prepared by Single RF Plasma Method

Methane(CH4) plasma was used to produce amorphous hydrogenated carbon(aC:H) films by a single capacitively coupled radio frequency(RF) powered plasma system.The system consists of two parallel electrodes:the upper electrode is connected to 13.56 MHz RF power and the lower one is connected to the ground.Thin films were deposited on glass slides with different sizes and on silicon wafers.The influence of the plasma species on film characteristics was studied by changing the plasma parameters.The changes of plasma species during the deposition were investigated by optical emission spectroscopy(OES).The structural and optical properties were analyzed via Fourier transform infrared(FTIR) spectroscopy,X-ray diffraction(XRD) and UV-visible spectroscopy,and the thicknesses of the samples were measured by a profilometer.The sp~3/sp~2 ratio and the existing H atoms play a significant role in the determination of the chemical properties of thin films in the plasma.The film quality and deposition rate were both increased by raising the power and the flow rate.     

Active Carbon Regeneration Experiment of Cold Neutron Source System on CARR

<正>When cold neutron source system on China Advanced Research Reactor(CARR)is running,the helium of helium refrigeration system required to pass through the compressor.But the compressor that we used is screw compressor,so in the process of the compressor compressed there is part of oil and impurities will be out of the compressor with helium.In order to purity of