基于同步辐射技术研究上海大气细颗粒物分布特征

用同步辐射X射线荧光分析(SRXRF)测定了上海市大气中粒径0.03-10 μm的13级颗粒物的元素组分,用X射线吸收近边谱(XANES)研究了颗粒物中S的化学价态.结果发现,在生活区和郊区,超细颗粒(<0.4 μm)对粒子质量浓度贡献较大,而工业区则细颗粒(1-10μm)对质量浓度贡献较大.元素浓度测定表明,吴淞工业区大气颗粒物中S、Ca、Ti、V、Cr、Fe、Ni、Cu、Zn和Pb元素浓度最高,且Ni、Mn、As和Pb等污染元素在细颗粒尤其是超细颗粒中有明显富集.化学价态测定显示,钢研所采样点不同粒径颗粒物中的S主要以硫酸盐形态存在,而在粒径<0.1μm 超细颗粒中还存在着一些还原态的低价态S.     

环境样品放射化学分析导论

一、放射化学分析在环境辐射监测中的作用放射化学分析是利用核素或核反应的特性,采用化学分离和核辐射测量的方法进行核素或元素分析。从学科上看,它是从放射化学与分析化学中派生出来的一个分支。随着原子能事业的发展,放射化学分析在核化学、放射化学、放射医学、环境保护、分析化学、地球和宇宙化学、考古学以及原子能工业、电子工业、地质矿山和冶金等部门得到越来越广泛的应用。     

化学种态分析软件CHEMSPEC最新进展

我国高放废物地质处置研发工作已经步入建造地下实验室阶段。地下实验室建造安全评价和未来的处置库性能评价中均需要关键放射性核素在相应深部地质条件下的扩散和迁移参数,而关键核素的扩散和迁移参数与核素在相应水岩体系中的化学种态密切相关。为满足我国核设施退役治理工作的需要,尤其是我国高放废物地质处置相关安全评价的需要,北京大学核环境化学课题组于2008年开始编写具有完全著作权的化学种态分析软件CHEMSPEC。经过多次修改和完善,目前已经具备了较好的计算功能。本文介绍该软件在表面配合模型、数据库补充和程序优化方面的最新进展,以实例形式介绍该软件的新性能,以期为我国相关实验研究者使用该软件提供参考。     

欢迎订阅 《核化学与放射化学》2023年征订启事 欢迎投稿北大核心CSCD

《核化学与放射化学》,1979年创刊,由中国核学会核化学与放射化学分会主办,是原子能技术类核心期刊。本刊的宗旨是为核化学与放射化学科学技术领域提供一个学术交流、成果推广的园地,以促进核化学与放射化学学科的发展。主要报道核化学与放射化学基础研究、放化工艺研究、辐射化学、同位素化学及有关分离分析方法的科研成果,适当报道国内外核化学与放射化学的新成就、发展动态及重要会议消息等。本刊主要设有综述、核燃料循环化学、核化学与放射分析化学、环境放射化学、放射性药物与标记化合物、放射化学交叉学科等栏目。读者对象主要是从事核化学与放射化学研究工作的研究人员、大专院校相应专业的师生以及有关的科技人员。     

《核化学与放射化学》2021年征订启事 欢迎订阅 欢迎投稿

《核化学与放射化学》,1979年创刊,由中国核学会核化学与放射化学分会主办,是原子能技术类核心期刊。本刊的宗旨是为核化学与放射化学科学技术领域提供一个学术交流、成果推广的园地,以促进核化学与放射化学学科的发展。主要报道核化学与放射化学基础研究、放化工艺研究、辐射化学、同位素化学及有关分离分析方法的科研成果,适当报道国内外核化学与放射化学的新成就、发展动态及重要会议消息等。本刊主要设有综述、核燃料循环化学、核化学与放射分析化学、环境放射化学、放射性药物与标记化合物、放射化学交叉学科等栏目。读者对象主要是从事核化学与放射化学研究工作的研究人员、大专院校相应专业的师生以及有关的科技人员。     

上海地区生活垃圾焚烧灰渣元素组成及微观特征研究

利用同步辐射X射线荧光法(Synchrotron radiation X-ray fluorescence,SR-XRF)、离子色谱(Ion Chromatography,IC)、扫描电镜及其能谱分析(Scanning electron microscopy and X-ray energy dispersive microanalysis,SEM-EDX)、同步辐射微束X射线荧光法(Synchrotron radiation micro-beam X-ray fluorescence,μ-XRF)等手段研究上海某垃圾焚烧厂生活垃圾焚烧产物飞灰(Fly ash,FA)、炉渣(Bottom ash,BA)的元素浓度、离子组成、微观形貌、元素面分布,采用电感耦合等离子体质谱(Inductively Coupled Plasma Mass Spectrometry,ICP-MS)和X射线吸收精细结构谱(X-ray absorption near-edge structure,XANES)研究灰渣中Pb的同位素比值和化学种态。研究发现,飞灰中多数金属元素浓度高于炉渣中的,Pb、Cd明显富集于飞灰中,元素的富集因子显示Pb、Cd、Cu、Zn等呈极度污染状态。灰渣中水溶性成分主要为Ca、Na、K的氯化盐和硫酸盐,飞灰中离子浓度普遍高于炉渣中的。飞灰颗粒相对于炉渣颗粒粒径小、表面粗糙,更易于重金属的吸附。灰渣颗粒物的元素Pb、Zn、Cu、Cr、Fe、Mn等并不是均匀分布的,而是呈现局部明显富集。飞灰和炉渣Pb的来源相似,化学种态相似,主要为PbCl2、PbS和PbO。生活垃圾在焚烧过程中元素的迁移分布与元素本身的特性、焚烧环境相关,上海地区生活垃圾焚烧飞灰是危险废弃物,需稳定化处理后才能填埋,炉渣的资源化利用必需经过预处理。     

对环境放射化学学科体系的探讨

环境放射化学是一门新兴的边缘学科,对其学科体系进行探讨十分必要。本文简述了这门新学科产生的背景和发展的历史;对环境放射化学的定义作了论述,并按不同方法对这门学科的研究内容作了分类和阐述;提出了环境放射化学研究的五个特点,并对该学科当前需研究的若干问题进行了讨论。     

分子活化分析法研究地质样品中铂族元素的化学种态

用化学逐级溶解、镍流火试金项富集及中子活化分析法研究了中国东部大陆地幔橄榄岩捕掳体中铂族元素的化学种态。分析结果表明，6个物相中单个铂族元素的质量分数加和与铂话元素总量分析结果基本相符；硫化物相中铂话元素分布特征的研究，进一步说明了硫化物的熔出是部分熔融过程中地幔橄榄岩铂族元素分异的重要机制之一。     

Se在北山花岗岩地下水中的化学形态及浓度控制分析

利用地球化学模拟软件GWB(Geochemist’s Workbench),研究了Se在我国高放废物预选场址北山花岗岩地下水中的化学形态及浓度控制因素。结果表明,Eh和pH对Se的化学形态影响较大,在处于弱碱性的北山花岗岩地下水中,溶解态的Se主要以SeO32-、HSeO3-和HSe-的形式存在。北山花岗岩地下水属于高矿化水,在保持地下水组分不变的情况下,当固定Eh为0mV,pH在5～12之间变化时,Se浓度主要受Se(0)、CuSe2、Cu3Se2或CuSe等矿物的沉淀所控制;当固定pH为7.56,硒浓度随Eh变化则主要受FeSe2、Se(0)、CuSe2、Cu3Se2或CuSe等矿物的沉淀所控制。与Fe2+相比,Cu2+更易与Se反应形成沉淀。从本文的模拟结果来看,由于Se在北山花岗岩地下水中易形成硒-矿物沉淀,使得溶液中的Se浓度能维持在较低水平,因此有利于阻滞对氧化还原条件敏感的核素79Se的迁移。     

分子活化分析

评述了可用于元素化学种态研究的分子活化分析技术的基本概念、实验方法、优缺点、以及在生物、环境和地学中的应用，并展望了分子活化分析的发展前景。     

Estimation of the inventory of the radioactive wastes in Fukushima Daiichi NPS with a radionuclide transport model in the contaminated water

Quantification of the radioactive waste inventory remaining inside the reactors at Fukushima Daiichi NPS is necessary to effectively plan their recovery, treatment, and disposal. Analysis of radionuclide concentrations and secondary wastes in the contaminated water treatment system can provide a means to estimate the radioactive waste inventory, which is not possible by more direct methods due to problems of accessibility and high levels of radiation. A predictive model has therefore been developed to estimate the radioactive waste inventory from the radionuclide concentrations and throughputs in the contaminated water. Model fitting has enabled the estimation of the key parameters, such as the initial radionuclide concentration C₀, the continuous release rate F, and inventory of source of continuous release I_S0. An estimated one-third of the total ¹³⁷Cs inventory has already made its way into the water treatment system as secondary wastes, whereas half still remains inside the damaged reactors as of 13 March 2014.     

Development of a Dynamic Food Chain Model DYNACON and Its Application to Korean Agricultural Conditions

A dynamic food chain model DYNACON was developed to simulate the radionuclide transfer on agricultural ecosystems. DYNACON estimates the radioactivity in each compartment of food chains for three radionuclides, nine plant species and five animal products as a function of the deposition date. A number of the parameter values used in this study are representative of Korean agricultural conditions. The model was expressed by coupled differential equations and the radioactivity in each compartment was solved as a function of time following an acute deposition. Although DYNACON is structurally based on existing models, it was designed in order to simulate more realistic radionuclide behavior in Korean agricultural conditions and to save computation time. It was found that the radioactivity in foodstuffs depends strongly on the date of deposition. A comparative study between DYNACON and an equilibrium model showed good agreement for depositions that occur during the growing season of plants. DYNACON is going to be implemented in a Korean real-time dose assessment system FADAS.     

Modelling the effect of diffusion into the rock matrix on radionuclide migration

Diffusion into the rock matrix is potentially an important retardation mechanism for nuclides leached from an underground radioactive waste repository in a fractured hard rock. Models of this diffusion process are discussed and incorporated into three-dimensional radionuclide migration models. Simple solutions to these models are derived for two regions: the region near to the repository where the nuclide is diffusing into effectively infinite rock, and that much further downstream where the concentrations in the rock and fractures are almost in equilibrium. These solutions are used to evaluate the possible impact of migration. It is shown that retardation factors in excess of 100 and reductions in the peak concentration at a given point on the flow path by three or four orders of magnitude are possible for non-sorbed ions, which would otherwise be carried by the flow and not retarded at all.     

水体放射性连续监测系统设计与仿真

论文设计了内陆水体中放射性核素连续在线监测系统,并采用蒙特卡罗方法对系统参数进行了优化。论文通过计算~(131)I、~(137)Cs、~(60)Co在不同水体厚度下探测灵敏度,结合系统造价,确定了系统最优化探测体积,并依据四川省水体中天然放射性核素浓度,计算了~(131)I、~(137)Cs、~(60)Co的判断限、探测限和定量限,该结果为内陆水体中放射性核素连续在线监测系统构建提供了技术参考和依据。     

Models for the release from fuel of Ce, La, Sr, and Eu in accident conditions

During a hypothetical severe nuclear accident involving a pressurised water reactor, it is of primary importance to assess the potential radionuclide releases into the environment. With that view in mind, analytical models have been developed for the release kinetics from fuel of four low-volatile fission products (namely cerium, lanthanum, strontium, and europium) in severe accident conditions. The vaporisation of those fission products from fuel has been evaluated by means of thermodynamic equilibrium calculations. The effects of the fuel temperature and the oxygen potential on the chemical form and volatility of the fission products have been determined. Finally, these models have been integrated in the ASTEC and have been subsequently validated against annealing experiments with various oxidizing and reducing conditions.     

高放废物地质处置库预选场址水文地质研究进展

深地质处置是目前国际上普遍接受的高放废物最终处置方案。对于这种处置方案而言，最有可能使处置库系统中放射性核素释放并进入生物圈的机制是地下水的作用。本文阐述了这种地下水的作用，包括地下水与工程屏障的相互作用、地下水在地质屏障中的核素迁移作用及核素滞留作用；介绍了处置库场址评价中水文地质研究的国际进展和动向；重点介绍了我国高放废物处置库预选场址水文地质研究进程和概况。     

循环柱实验装置的建立及其在核素迁移实验研究中的应用

本文介绍循环柱实验装置的特点以及在核素迁移实验研究中的应用。该装置是将实验介质如石英砂或黄土填充在有机玻璃柱中，联接所有管路接头并密封，即可进行实验。采用该装置进行实验时，淋洗液在柱中多次循环，直到循环流出液的放射性浓度基本不变，它具有静态和动态实验的特性。经实验验证，所建立的循环柱实验装置设计配置合理、运行稳定、操作方便。采用不同介质分别与^237Np和^238Pu在循环水作用下，进行了核素迁移实验。结果表明：循环柱实验结果与静态实验结果有明显的相对可比性（即相关性），它可替代静态法和动态法，用来测定吸附分配比、分析核素在介质中的迁移分布状况。所得结果更接近现场实验结果。     

Immobilization of 137Cs and 60Co in concrete matrix. Part 2: Mathematical modeling of transport phenomena

There are two fundamental issues that must be addressed in an attempt to isolate low-level waste in a disposal facility on land. The first is the isolation of waste from water, or hydrologic isolation. The second is prevention of radionuclide leakage from the disposal facility, or radionuclide migration. We have investigated here the latter modified scenario. Transport phenomena involved in the leaching of a radioactive material from a cement composite matrix have been investigated using an empirical method employing a polynomial equation. The results presented in this paper are examples of the results obtained from a 25-year mortar and concrete testing project, which will influence the design of the engineered trench system for a future central Serbian radioactive waste storage center.     

Radioactive contamination of bukhtas and bays on the Kola Peninsula and Novaya Zemlya and in the Far East

The characteristics of the radioactive contamination of bukhtas and bays are determined: the nonuniformity of the radionuclide distribution in the water and bottom deposits, the rate of accumulation of sediments, the distribution ratio, and the turbulent diffusion coefficient. A characteristic feature is the strong nonuniformity of the radionuclide distribution in bottom sediments. A mathematical model is proposed for radionuclide transport and water of bukhtas taking account of flow, turbulent diffusion, and settling of suspensions. Possible explanations are proposed for the characteristics of the radionuclide distribution in bukhtas. The reason for weak turbulent diffusion in bukhtas is examined. __________ Translated from Atomnaya énergiya, Vol. 103, No. 10, pp. 263–268, October, 2007.