高放废物处置库野马泉预选场址地下水放射性同位素特征

甘肃北山野马泉地区是我国高放废物处置库预选场址之一.文章阐述高放废物处置库天然类比研究的主要内容,并阐述类比研究中涉及的地球化学问题.以野马泉岩体为例,研究地下水铀、钍含量及放射性特征、铀同位素特征.初步认为,在当地的地质、水文地质等环境条件下,铀的迁移能力有限,迁移距离较小.这一认识为预选场址评价提供了重要的信息和依据.?＃     

花岗岩中高放废物地质处置库系统分析方法研究

首先以甘肃北山预选区花岗岩场址为例,提出该场址中高放废物地质处置库概念设计和结构设计,然后以系统分析方法论为基础,描述处置库的系统功能、结构、环境及其演化过程.并以模拟软件GoldSim为工具,建立该处置库演化过程的计算机模型,最后以该计算机模型为模拟实验平台,模拟处置库中辐射毒性时空分布,分析模型中的参数灵敏度,优化设计参数,并预测和评价处置库性能.其研究成果可为合理配置资源和有效协调各研究项目之间关系提供技术支持.     

澳大利亚确定低放核废物国家最终处置库场址

【澳大利亚铀信息中心2003年5月16日报道】 澳大利亚科学部部长2003年5月9日宣布,澳大利亚国家最终处置库将位于40a号场址。 40a号场址位于澳大利亚南部伍默拉地区,是该地区3个适于作为低放和短寿命中放废物的国家最终处置库的候选场址之一。2001～2003年,澳大利亚一直根据《1999环境和生物多样性保护法案》对该地区的3个场址进行评估。在参考了有关处置库建议的《环境影响报告》(EIS)后,澳大利亚环境和遗产部部长指出,教育、科学和培训部必须在40a号或45a号场址建造国家最终处置库。 科学部之所以做出这种选择是因为相对于45a号场址,40a…     

塞拉菲尔德被选为英国低中放废物处置库场址

【英国《国际核工程》1991年9月号第6页报道】作为进一步调查发展英国中低放废物地下处置库场址,英国核工业放射性废物管理局(Nirex)已选择了塞拉菲尔德,而没有选择当里。耗资5000万英镑历时两年的调查发现,上述两个场址的地质状况都有可能适合作为处置库场址;但是,运往该处置库的60%的     

高放废物处置库野马泉预选地段地下水铀存在形式及迁移特征

甘肃北山野马泉地区是我国高放废物处置库预选场址之一。本文以该预选场址为例,在地下水铀、钍含量及其同位素比值测试、分析基础上,计算了铀存在形式。结果表明,地下水中的铀主要以U(OH)₄(aq)形式存在。探讨了铀的迁移特征,认为在当地的地质、水文地质等环境条件下,铀的迁移能力很低。     

瑞典核废物最终处置库计划得到支持

【英国《国际核工程》2004年7月刊报道】瑞典国家核燃料和废物管理公司(SKB)建设核废物最终处置库的计划得到公众支持。2个核废物最终处置库候选场址所在地区的最新民意调查表明,69%的奥斯萨玛(Osthammar)居民支持或全力支持在当地建设深层地质处置库,而奥斯卡港(Oskarshamn)的这一数字为72%。自从上一次民意调查以来,不但候选场址所在地区的公众对处置库计划的支持率一直在上升,而且周边地区的公众支持率也在增加。SKB总经理ClaesThegerstrom表示,民意调查结果表明,离候选场址越近的居民越支持处置库的建设。这可能是由于经过多年的宣…     

对我国高放废物处置研发工作的几点建议

论述了高放废物处置库与一般地下工程设施的区别,以及处置库场址的选址工作与低中放废物处置场和核电站场址的选址工作异同点。强调要高度重视高放废物处置的安全性,这是由于高放废物毒性大、半衰期长、安全处置期长;由于处置库堆放的废物总比活度大,且高放废物处置在地下深处,因而,如果一旦处置库系统遭受破坏,就难以进行人工干预。笔者认为,在区域预选和地区(地段)预选阶段,查明场址区域地壳稳定性问题是其首要任务。文章就处置方案等若干问题进行了讨论。     

我国高放废物地质处置库场址筛选总体技术思路探讨

绿合对比瑞典、加拿大、芬兰和美国等国高放废物地质处置场址筛选技术思路,分析国外高放废物地质处置库场址筛选过程中取得的经验、教训,总结了我国处置库选址工作取得的成果和存在的问题.在综合研究基础上,分析提出我国高放废物地质处置库场址筛选总体技术思路,包括应遵循的原则、工作范围、目标和总体技术步骤等,以利于今后处置库选址工作更系统、规范和统一.     

法国泥岩中的高放废物候选处置库场址Cigéo

为了便于对比研究,我国高放废物地质处置的处置库围岩,除选择花岗岩外,还对黏土岩进行了研究,这项工作虽起步于20世纪80年代中叶,但当时未得出我国在黏土岩中建造处置库可行性的确切结论.近年来,我国再度启动黏土岩中高放废物处置库场址的选址工作,以查明我国在黏土岩中建库的可行性.国外有些国家,如比利时和法国等,对此领域进行过多年的研究,并取得了一些十分可喜的成果,主要介绍位于黏土岩中的法国Bure URL和以此为基础发展起来的Cigéo候选处置库场址的选址工作,包括选址历程、场址推荐理由、Bure URL概况、候选处置库设计方案、今后法国在此领域的研发工作规划和笔者的几点认识.按现规划,Cigéo处置库将于2018年开始建造,2025年开始运行.     

中国公开放射性废物处置计划

【欧洲核学会《核新闻网》1994年11月11日报道】中国原子能机构(CAEA)副主任李定凡最近宣布了中国的放射性废物处置政策的细节。 中国计划建造4座低、中放固体废物的区域性处置库。 在中国西北部一座处置库的初步设计工作业已开始。该处置设施的第一期处置能力为6万立方米,但根据长期规划,其最终处置能力将达20万立方米。 在中国南部的另一座处置库的场址选择工作和可行性研究现已完成。其余2处场址     

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.     

Characteristics of pulsed photo-stimulated luminescence and thermoluminescence for the identification of gamma irradiated poultry eggs

Pulsed photo-stimulated luminescence (PPSL) is a simple screening method that can be employed qualitatively at the spot for the detection of eggs treated with ionizing radiation.Due to the variations in the results during storage,the eggs of ostrich,duck,hen,and quail were irradiated to doses of 0,1,2,and 3 kGy.Most of the samples were incorrectly identified during storage after four months of irradiation.Thermoluminescence (TL) technique was also tried by using egg shells in order to confirm the irradiation treatment in eggs.TL glow curves were recorded between the temperatures 50℃to 400℃at the rate of 5°/s for all the control and irradiated samples.On the basis of integrated areas of first glow curves (TL1),the glow curve ratios (TL1/TL2) and the shapes of maxima of TL1, the irradiation treatment of all the eggs was confirmed.Furthermore,the presence of calcite and aragonite minerals that cause the TL signal in the egg shells were studied using X-ray diffraction spectrometry.     

数字射线扫描成像系统MTF的测试分析

为有效实现数字射线扫描成像检测系统性能的定量分析评价,据此进行检测工艺参数的优化,对数字射线扫描成像检测系统调制传递函数(Modulation transfer function,MTF)进行了测试分析。采用刀口工具、双线型像质计、分辨率测试卡,对系统在不同焦点大小、放大倍数、运动方向的检测情况,分别进行了MTF的测试并进行了比较。结果表明,双线型像质计与分辨率测试卡的测试结果基本一致,但双线型像质计更便于对比度的定量计算;双线型像质计的对比度传递函数近似符合二次曲线,经转换得到的调制传递函数值高于刀口法的测试值,刀口法计算数值偏低的原因在于运动不平稳所带来的不利影响。分析表明,数字射线扫描成像系统性能受到多个因素的共同影响,MTF测试结果可较全面地对影响因素进行定量评价,可用于确定最佳的检测参数或找出等价的参数组合。     

基于物理体模CT图像的1岁儿童体素体模构建

本文介绍了基于1岁儿童物理体模（Model 704-D）的CT图像和中国成年男性参考人体素体模(CRAM)的1岁儿童体素体模（CPP01）的构建,包括通过对物理体模扫描得到OCP01体模（基于儿童物理体模的CT图像建立的一粗略的体素体模）,进而构建和优化CPP01。该体素体模的各器官组织的质量与GBZ/T 200.2-2007所给数据的相对偏差约在5%以内,且其外部轮廓和主要器官的位置与Model 704-D相匹配。     

Activity level of gross α and gross β in airborne aerosol samples around the Qinshan NPP

The monitoring results of gross α and gross β activity from 2001 to 2005 for environmental airborne aerosol samples around the Qinshan NPP base are presented in this paper. A total of 170 aerosol samples were collected from monitoring sites of Caichenmen village, Qinlian village, Xiajiawan village and Yangliucun village around the Qinshan NPP base. The measured specific activity of gross α and gross β are in the range of 0.02 ～ 0.38 mBq/m3 and 0.10 ～ 1.81 mBq/m3, respectively, with an average of 0.11 mBq/m3 and 0.45mBq/m3, respectively. They are lower than the average of 0.15 mBq/m3 and 0.52mBq/m3, of reference site at Hangzhou City. It is indicated that the specific activity of gross α and gross β for environmental aerosol samples around the Qinshan NPP base had not been increased in normal operating conditions of the NPP.     

Simulation of the mixing process in FCIs with hydrodynamic fragmentation model

Fuel Coolant Interactions (FCIs) are important issues in nuclear reactor severe accident analysis. In FCIs, fragmentation model of molten droplets is a key factor to estimate degree of possible damage. In this paper, the mixing process in FCIs is studied by the simulation of MIXA experiment with hydrodynamic fragmentation model. The result shows that hydrodynamic fragmentation model underestimates the fragmentation rate of high temperature molten droplets under the condition of low Weber numbers. It is concluded that models based on thermal fragmentation mechanism should be adopted to analyze the FCI process and its consequence.     

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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NUCLEAR SCIENCE AND TECHNIQUES Volume 25,2014

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Probing stray surface electric patch fields using Rydberg atoms

The stray electric “patch” fields present at a Au(1 1 1) surface are investigated by studying the ionization of Rydberg atoms incident at near-grazing angles. Measurements of the threshold conditions required to observe the resulting ions are used to estimate how large such stray fields can be. The data show that the stray fields can be sizeable, as large as ∼10³ V cm⁻¹ 100 nm from the surface and ∼20 V cm⁻¹ 500 nm from the surface, and illustrate the potential of Rydberg atoms for detecting and characterizing surface electric fields.