中子活化瞬发γ射线元素分析技术初探

自六十年代中期以来,中子活化瞬发γ射线元素分析技术(PNAA)在地质勘探、材料成份分析、工业流线监测、以及医学生物学中得到实际应用。与通常的中子活化(NAA)技术相比,它分析的是样品主要成份的百分比含量,由于可利用同位素中子源,这样可在现场进行在线测定。PNAA和NAA一样,都是非破坏性分析,它适宜于大块物质的体分析、生物     

铀芯块样品的核法证分析研究

正核法证学研究能有效应对核安全事件和潜在的核恐怖威胁,防止放射性犯罪或恐怖袭击。通过对核燃料循环不同阶段的核材料分析,揭示核材料的初始来源和整个历程,发现由于不同地质条件与工业过程而遗留在核材料独特的、可区分的特点。在核材料分析过程中,核材料"年龄"、痕量杂质与稳定同位素组成等特征非常重要。本工作以核燃料循环中最重要的产品铀芯块为分析对象,采用核法证分析技术溯源铀芯块的     

从工业γ射线探伤应用中的辐照事故看企业放射源管理

工业γ射线探伤放射源相比其他核技术利用行业用放射源,由于其体积小、重量轻、便于携带等特点,在管理不善情况下,更容易发生事故并产生较大的危害。本文简要总结了我国及其他国家工业γ射线探伤应用中的辐射事故教训,分析事故发生原因,提出工业探伤放射源的管理建议以减少因放射源失控造成的辐射事故的发生。     

美国控制数据公司简介

目前美国控制数据(CDC)公司的Cyber计算机已在全世界核电工业中广泛应用,特别是四大核电设备制造厂(西屋、通用电气公司、燃烧公司及巴布科克和威尔科克斯公司)在反应堆的设计和分析中全都采用cy ber系统。在核电工业中,有许多核应用软件都是     

从工业γ射线探伤应用中的辐照事故看企业放射源管理

工业γ射线探伤放射源相比其他核技术利用行业用放射源，由于其体积小、重量轻、便于携带等特点，在管理不善情况下，更容易发生事故并产生较大的危害。本文简要总结了我国及其他国家工业γ射线探伤应用中的辐射事故教训，分析事故发生原因，提出工业探伤放射源的管理建议以减少因放射源失控造成的辐射事故的发生。     

中子水分仪测量方式的改进研究

中子水分仪在工业现场应用时,有时会因被测量物料中水分不均匀而引起测量误差。本工作利用蒙特卡罗方法模拟了中子水分仪应用中由于物料中水分不均匀所带来的测量误差。为了减小由于水分不均匀带来的测量误差,提出了一种新型的测量方式,即透射加散射测量方式。实验证明,透射加散射测量方式能够有效降低中子水分仪在被测量物料水分分布不均匀情况下的测量误差。该方法用于水分分布复杂条件下的现场测量还需作进一步的分析和研究。     

铀成矿学现实问题

目前,由于对铀矿床形成条件的观点不同。还缺乏一种统一的铀矿床分类方法。苏联学者提出以大地构造学为基础的前寒武纪含铀区域的划分方案。在划分出的每个前寒武纪地壳大地构造单元类型中均产有一定工业类型的矿床(表1)。工业矿床产于活动带和克拉通活     

内生铀矿床成矿物质来源

众所周知,研究地质过程的演化问题是研究地质科学的基础。地质学家非常重视金属矿床在地槽褶皱系、地台和构造岩浆活化区发展史中的位置。由于铀在自然界中非常活跃,以及工业铀矿床产出的地质环境的多样性,因此在这方面铀矿床具有特殊的意义。     

氟和含氟化物的分离和测定方法

一、前言氟及其化合物广泛分布于自然界中,与人类关系极为密切。例如氟化物在原子能工业中起着关键性的作用;在石油、橡胶、塑料等部门中也是重要的组成元素,很有价值;在农药、医药、制铝、冷冻、水处理等工业中也有重要的地位;甚至环境保护、生物生态、人类健康等都有重要作用。因此,其测定方法早为人类所重视。由于氟是极其活泼的元素,与许多元素都有强烈的络合作用,如与常见的元素铁、     

哈萨克斯坦铀工业的困厄及对策

哈萨克斯坦拥有丰富的铀、石油、天然气、煤资源,是世界上最重要的能源矿产地之一。在计划经济向市场经济的转换进程中,哈萨克斯坦铀工业的生存与发展遇到了强劲的挑战和机遇。一方面,由于资金匮乏,铀生产设备与工艺陈旧,铀工业活动导致的环境问题严重,给铀工业的生存带来众多困厄;另一方面,哈境内业已探明的大量低成本、可地浸砂岩铀资源是国家潜在的宝贵财富。多渠道引进外资(向世界银行贷款改造、开发地浸砂岩铀矿山,让外资或由外商与哈合营开发铀矿、积极出口铀、接纳境外核废等)已成为哈萨克斯坦在新世纪初振兴铀工业的希望。     

Identification of radiation treatment of wheat （Triticum aestivum. L）and rice （Oryza sativa. L） samples using thermoluminescence of contaminating minerals

Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence （TL） is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture （NIFA）, Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities （TL1） than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves （TL2）. The ratio of the area of first glow curve to that of second glow curve （TL1/TL2） was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results （comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves）, all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.     

The preclinical pharmacological study of dopamine transporter imaging agent 18F-FP-β-CIT

The paper is to study pharmacologic characteristics of 18F-FP-β-CIT (18F-N-(3-fluoropropyl)-2β- carbomethoxy-3β- (4-iodophenyl)nortropane) as an imaging agent for dopamine transporter. The radiochemical purity of 18F-FP-β-CIT in aqueous solution was over 95% after standing at room temperature for 4h. Biodistribution displayed rapid uptake in rat brain (1.375 %ID/organ at 5min and 0.100 %ID/organ at 180 min) and the striatal uptake was 1.444,0.731, 0.397, 0.230 and 0.146 %ID/g at 5, 30, 60, 120 and 180 min, respectively. The values of striatum/cerebellum,striatum/frontal cortex and striatum / hippocampus in rat's brain at 30 min were 3.38, 2.17 and 2.40 respectively. The uptake in striatum can be blocked by β-CFT, suggesting that 18F-FP-β-CIT binds to DAT peculiarly. The compound was rapidly cleared from monkey's blood. The striatal uptake was bilaterally decreased in the left-sided lesioned PD rats, compared with normal control. Brain PET imaging studies in normal monkey showed that 18F-FP-β-CIT was concentrated in striatum. The test of undue toxicity showed that the dose received by mice was 1250 times as by human, which indicates that 18F-FP-β-CIT is very safe. So 18F-FP-β-CIT is a promising PET imaging agent for DAT with safety and validity.     

PLASMA SCIENCE AND TECHNOLOGY AUTHOR INDEX TO VOLUME 16(2014)

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Radioactivity levels in soil of salt field area,Kelambakkam,Tamilnadu,India

Soil samples in and around salt field area have been analyzed for natural radioactivity concentration using gamma ray spectrometer.The activity concentration for ~(232)Th,~(238)U and ~(40)K are ranged from 27.88 to 45.27 Bq/kg, from BDL to 13.30 Bq/kg,and from 135.54 to 381.28 Bq/kg,respectively.The measured activity concentrations for these radionuclides were compared with world average activity of soil.The average activity concentration of ~(232)Th in the present study is 1.19 times higher than world median value while the activity of ~(238)U and ~(40)K is found to be lower. The absorbed dose rates due to these radionuclides were calculated.The average absorbed gamma dose rate due to the presence of ~(232)Th,~(238)U and ~(40)K in soil samples is 36.99 nGy·h~(-1).These results indicate no radiological anomaly. The data presented in this study will serve as a base line survey for primordial radionuclides concentration in the study area.     

Non-FDG PET imaging of brain tumors

Due to relatively high uptake of glucose in the brain cortex, the use of FDG PET imaging is greatly limited in brain tumor imaging, especially for low-grade gliomas and some metastatic tumours. More and more tracers with higher specificity were developed lately for brain tumor imaging. There are 3 main types of non-FDG PET tracers： amino acid tracers, choline tracers and nucleic acid tracers. These tracers are now widely applied in many aspects of brain tumor imaging. This article summarized the general use of non-FDG PET in different aspects of brain tumor imaging.     

基于NPL-NMC系统的γ测量子系统的建模与优化

在军控核查中,核部件的质量、丰度、年龄属性需采用无损方法进行核查,NPL-NMC系统是一套利用中子多重性测量核部件质量属性的装置,为建立完善的属性测量系统,还需在NPL-NMC系统的基础上建立γ测量子系统。本文通过设计γ测量子系统在NPL-NMC系统上的布局及对中子屏蔽的优化,使系统能对铀部件的丰度、年龄属性进行测量。模拟计算结果表明,该γ测量子系统能很好地满足军控核查对铀部件丰度、年龄属性测量的要求。     

Improvement of carbon fiber surface properties using electron beam irradiation

Carbon fiber-reinforced advance composites have been used for structural applications,mainly on account of their mechanical properties.The main factor for a good mechanical performance of carbon fiber-reinforced com- posite is the interfacial interaction between its components,which are carbon fiber and polymeric matrix.The aim of this study is to improve the surface properties of the carbon fiber using ionizing radiation from an electron beam to obtain better adhesion properties in the resultant composite.EB radiation was applied on the carbon fiber itself before preparing test specimens for the mechanical tests.Experimental results showed that EB irradiation improved the ten- sile strength of carbon fiber samples.The maximum value in tensile strength was reached using doses of about 250 kGy.After breakage,the morphology aspect of the tensile specimens prepared with irradiated and non-irradiated car- bon fibers were evaluated.SEM micrographs showed modifications on the carbon fiber surface.     

Measurement system for SSRF pulsed magnets

This paper describes the magnetic field measurement system for pulsed magnets in SSRF.The system consists of magnetic probes,analog active integrator,oscilloscope,stepper motor and a controller.An application pro- gram based on LabVIEW has been developed as main control unit.After the magnetic field mapping of a septum magnet prototype,it is verified that the test results accord with the results of theoretical calculation and computer simulation.     

旁路阀调节对高温气冷堆闭式布雷顿循环瞬态特性影响研究

闭式布雷顿循环是第4代高温堆核能系统的关键技术之一,其典型的动态过程是旁路阀调节。为分析这一过程,建立了循环中关键部件的动态模型,其中压气机在径向平衡模型基础上耦合了对附面层发展的预测,兼顾了计算效率与准确性;换热部件模型基于双曲型守恒律方程,对工质的热物性和参数的快速变化有较好的适应性。在此基础上根据回路的质量守恒和压力平衡原则将各部件的模型耦合,建立了系统的动态模型。由于旁路阀调节是氦气透平发电系统主要的功率快速调节手段,瞬态效应较为显著,以模块式高温气冷堆（HTR-10GT）旁路阀开启后的过渡过程作为算例,分析了主要循环参数的响应特性,并通过分析,给出了降低输出功率的机制。计算结果表明：系统的容积惯性对旁路阀调节的响应速度影响较大,而阀门的开度则决定了系统在末态的输出功率;回热器的温度冲击现象可能发生在调节过程中,但可通过两旁路阀联动的方式缓解;反应堆出口温度变化幅度很小,因此反应堆模型的准确程度对结果基本无影响。     

CEFR 100%额定功率运行汽轮机发电能力分析

中国实验快堆(CEFR)首次100%额定功率发电运行中,实际电功率较设计值相差较多。为判断影响机组实际发电能力的主要原因,以现场采集的运行数据和汽轮机厂商提供的设计资料为基础,进行了相应的计算分析。对汽轮机内效率进行修正,绘制汽轮机近似热力过程曲线,并通过实测的各段抽汽压力,在热力过程曲线上获得抽汽焓值;利用换热器的能量守恒和流量守恒的基本方程进行除氧器和各加热器的热平衡计算,获得各段抽汽的流量;利用汽轮机的功率计算方程,得到汽轮机发电功率的计算值。通过计算值与实际值的比较分析,得出主蒸汽参数不达标是影响CEFR汽轮机发电能力的主要因素。