X射线吸收谱学在锕系环境放射化学中的应用

锕系环境放射化学对于核废料尤其是高放废物的安全处理和处置至关重要,同步辐射技术尤其是X射线吸收谱学在解析锕系元素在不同介质表面的配位结构方面可以发挥关键作用,对于理解锕系元素在环境介质中的迁移转化行为意义重大.本文综述了近年来国内外利用X射线吸收谱学研究锕系元素环境化学方面的最新进展,主要包括锕系核素在不同地质条件下的迁移和转化以及微生物对核素迁移的影响等方面.     

地球化学模拟在高放废物地质处置中的应用与发展

随着核能事业的发展,高放废物的处理和处置问题日益突出.其中,研究高放废物在环境介质中的吸附、扩散和迁移行为是获取放射性核素对周围环境和人群健康影响的基础参数的最重要和最直接的途径.近年来,人们利用已有的实验数据及核素的基础热力学和动力学数据,附以相应的数学模型,建立了一些地球化学模拟软件,用于分析核素在地质介质中可能发生的连续性和长期性变化.目前,国内外常用的地球化学模拟软件有十多种.本文从热力学平衡计算原理、种态分布计算方法和表面配位模型假设等几个方面对地球化学模拟软件进行了简要介绍,对近年来地球化学模拟软件在核素种态分布计算和表面配位模型模拟两方面的应用进行了举例分析,并以Ca-U-CO3配合物为例,说明完备的热力学数据对地球化学模拟软件发展的重要性,以期促进我国地球化学模型的应用和发展.     

高放废物地质处置中的模型

我国将采用深地质处置的方法处理核能发展所产生的大量高水平放射性废物。为了准确地预测核素的迁移行为,评估处置库的安全性,除了实验之外,还必须使用模型。本文对高放废物地质处置中所涉及的模型,以及与模型相关的软件、数据库做了综述,重点叙述了用于化学种态分析的地球化学模型,扼要介绍了多场耦合模型。此外还简要报告了本实验室核素迁移实验数据的处理方法和程序。     

稀土精矿冶炼过程放射性元素迁移分布规律

中国稀土资源储量巨大,但多为天然放射性核素伴生矿,放射性污染问题一直以来都是关注的焦点。随着稀土矿石的开发利用,这些放射性核素随之迁移,扩散,重新分布和富集,并随着稀土矿冶炼过程产生的三废进入到环境中,处理不当就会成为严重的环境污染问题,也会造成资源的浪费。放射性核素是核能发展中的重要元素,为了更好地利用处置放射性核素,应该清楚这些核素的迁移、分布和富集过程和规律。通过实地调研,考察和查阅大量文献,总结出几大稀土矿主流冶炼工艺过程中放射性元素的迁移分布规律和富集过程。结果表明:几大稀土矿虽然冶炼工艺不同,但其中放射性元素90%左右迁移、富集到冶炼废渣中,剩余少部分分布到废水、废气及产品中。因此,需要加大稀土矿冶炼新工艺的研究及现行工艺的技术改造,从源头解决放射性废渣的污染和堆存问题;研究开发现存的冶炼废渣中稀土、钍(铀)等有价元素回收利用工艺,实现废渣减量化、资源化和无害化。     

四苯硼钾由单-到不同混合溶剂的迁移自由能

KBPh4作为一种典型的大阴离子电解质 ,在研究与计算大分子电解质的迁移热力学性质中起着重要的作用 .讨论大分子电解质与不同溶剂间的作用 ,还可以为萃取、色谱及表面活性剂的研究提供理论依据 .一些文献及我们前文曾对四苯硼盐由水到一些纯溶剂 [1,2]及从水到某些水-有机混合溶剂中的标准迁移自由能进行了研究 [3],但对四苯硼盐在有机-有机混合溶剂中的研究报导极少 .本文对 KBPh4由水到水-异丙醇和由甲醇到甲醇-异丙醇混合溶剂的标准迁移自由能进行了研究和探讨 .1实验部分 1.1实验仪器及方法 　　用 CS501型超级恒温槽恒温 ;用 WF…     

AOT-正庚烷微乳状液的制备及迁移痕量金属离子的研究

研究了以二－(2－乙基已基)磺化琥珀酸钠为表面活性剂、以正庚烷为油性溶剂的W/O型微乳状液的形成及迁移痕量金属离子的行为,确定了制乳和迁移的适宜条件.在此条件下,一些金属离子可较完全地从水相或料相迁移到微乳相中,显示出较高的迁移率.     

新核素研究中的放射化学分析方法及其意义

简述了放射化学分析方法的创立，定义和新核素研究中的放射化学分析方法及其意义     

AOT—正庚烷微乳状液的制备及迁移痕量金属离子的研究

研究了以二－（２－乙基己基）磺化琥珀酸黄为表面活性剂，以正庚烷为油性溶剂的Ｗ／Ｏ型微乳状液的形成及迁移痕量金属离子的行为，确定了制乳和迁移的适宜条件，在此条件下，一些金属离子可较完全地水相或料相迁移到微乳相中，显示出较高的迁移率。     

新核素研究的放射化学分析方法及其意义

简述了放射化学分析方法的创立，定义和新核素研究中的放射化学分析方法及其意义。     

对比超声剪切波弹性成像与核素SPECT显像对甲状腺癌的诊断价值

目的探讨超声剪切波弹性成像与核素同核素SPECT显像在甲状腺诊断中的应用价值。方法选取甲状腺疾病患者43例(62个甲状腺结节)为研究对象,分别行核素SPECT显像及超声剪切波弹性成像检查,对比两种检查结果。结果剪切波弹性成像的灵敏度为90.48%,特异度80.49%,准确率为83.87%,核素SPECT显像分别为61.90%、65.82%、66.13%,差异均有统计学意义(P<0.05)。结论在甲状腺癌诊断中,超声剪切波弹性成像临床价值较核素SPECT显像高,更值得推广。     

China's progress in radionuclide migration study over the past decade (2010–2021): Sorption,transport and radioactive colloid

The radionuclide (RN) migration study is not only helpful to understand environmental behavior of RNs, but also can establish the basis for the safety assessment of geological disposal of high-level radioactive waste (HLW). In the context of China's HLW disposal, this review briefly summaries the progress of China's RN migration studies over the past decade regarding three aspects, RN sorption, RN transport and radioactive colloid. Domestic studies from other disciplines (such as geology and environmental science) are also included in this review because they can provide references for the RN migration study. Overall, China has achieved clear progress in RN migration study over the past decade, although large-scaled field experiments are lacked and a gap still exists comparing with the international advanced level. Finally, several suggestions are proposed for future RN migration research in China.     

Studies on the adsorption and migration of radium in natural minerals

The aim of this paper is to consider using effective natural minerals in studying the retardation and migration of radium under the influence of groundwater in the far-field of a radioactive waste repository. The properties of adsorbing radium by minerals are studied by adopting the static and dynamic adsorption method. Preliminary experimental results give confidence in the validity of using Maifanshih and barite to adsorb radium in water and to serve as effective retarding materials in radioactive waste repositories, their Kd values being 3815 and 2955, respectively. The study on a certain number of conditions of adsorbing radium by the promissing material Maifanshih is reported for the first time. The mechanism of radium adsorption has been discussed and modeling of migration of radium in the minerals has been presented to establish a rational basis for the longterm prediction required for safety assessment of underground disposal of radioactive waste.     

Speciation of Neptunium Migration in under Groundwater

The migration of radionuclides with groundwater into the environment of a radioactive waste repository is an important aspect in evaluating the safety assessment of such repositories. The potential transport and fate of these radioactive species are dependent upon their speciation and the geochemical behavior of the predominant ones. The speciation of different valence states of neptunium [Np(IV, V and VI)] and their migration behavior are investigated. The data revealed that the uptake is highly dependent upon pH and the distribution coefficient (K _d) is depressed by the presence of organic ligands. The relative migration velocities (V _n) of the valence states relative to that of groundwater, in the concerned area, clarified that Np(V) is the most mobile species and their transport rates are highly accelerated by the presence of humic acid. Also, a radionuclide dispersion model was applied to elucidate the migration behavior of these radioactive species in the selected site and to quantitatively predict their concentrations at different distances in both x and z directions over long time scales.     

Determination of retardation factors of137Cs in migration process in concrete

Determination of retardation factors and coefficients of distribution using a simplified mathematical model for analyzing the migration of leachate and radioactive material contained in radioactive waste burial concrete trench systems has been developed. Results show that concrete for engineered trench systems secures radionuclide preservation in solidified medium for longer than 300 years. These results will be used for constructing future radioactive waste storing centers in Yugoslavia.     

Fast method for the detection of transport processes in plant tissues by radiotracing

The efficiency of nutrients, microelements and plant protective agents and additives applied on foliar and various aeriel parts of plants depends on the adsorption of their spray drops and the penetration of agents into tissues, cells and inner caves. The permcability of tha cuticular membrane and the mode of entry of above substances through the cuticle and their mobility in other tissues are poorly understood but have been the subject of intensive research. The traditional methods in biological systems are the automicroradiography and sample taking methods. The radioactive tracer method developed by us is suitable for determining the effective diffusion coefficients characterizing the migration processes and concentration distributions of these materials in plants by consumption of minimal amount of -labelled radioactive isotopes in very short time.     

Migration of 85Sr in unsaturated Chinese Loess: An in-situ test

As part of a co-operative research project between the China Institute for Radiation Protection (CIRP) and the Japan Atomic Energy Research Institute (JAERI) on safety assessment method for shallow land disposal of low level radioactive wastes, the migration of ⁸⁵Sr in unsaturated Chinese loess under natural and artificial rainfall conditions was in-situ investigated. ³H was used for obtaining the migration velocity of the moisture water in the test zone. The result of the 2-year test indicated that under natural rainfall conditions, the migration of ⁸⁵Sr is a combination of downward and upward movements. It moves down in summer and moves up in winter. Under artificial rainfall conditions the migration of ⁸⁵Sr is a velocity-change process. It migrates down faster in summer and slower in winter. This phenomenon is considered to be caused by the dry winter and relatively wet summer.     

当前我国放射性核素迁移的实验研究

本文综述了当前我国放射性核素主要是锶铯碘铀的迁移研究，并指出了今后的发展方向。     

Main sources of radioactive contamination in Russia and methods for their determination and speciation

This paper desribes the main sources of radioactive contamination of Russia and some techniques elaborated in the V. I. Vernadsky Institute of Geochemistry and Analytical Chemistry for the determination and speciation of radionuclides in the environment. Data on radioecological monitoring of the zone affecting by Production Association “Mayak” are presented as example of the use of these techniques. Some problems of the calculation of radionuclide migration coefficients and the determination of their so called geochemical forms of occurrence are discussed.     

Measuring soil pollution parameters with radiotracers

Summary An alternative method has been proposed and performed to determine the relevant soil parameters - such as dispersitivity and distribution coefficient - related to the use of a tract of land for a toxic waste repository. The method makes use of radioactive tracers and a geotechnical centrifuge to accelerate relevant migration processes. A few soil types and tracers have been employed. Experimental data were then compared to those predicted by the advection-dispersion equation. Preliminary results indicate that this alternative method is useful for the determination of the above parameters, especially when fine soils are involved.     

Effects of uranium mining on radioactive contamination in the Kletno Region in Poland

In the Lower Silesia region, in the vicinity of Kletno town (near Kodzko), there are remainders of uranium ores being mined there, such as dump sites, abandoned pits and the like. Extensive research has indicated an increase in radioactivity there. The present research was aimed at defining the radioactive contamination in the neighborhood of Kletno. The research involved gauging the radiation background, especially at the mine dumps and measuring the concentration of natural radioactive isotopes and Cs in the rocks and soil. Besides, the concentration of radium isotopes in waters was determined. Two spots only were found with higher radiation levels. A method for dealing with radiation hazards is proposed. Water analyses have indicated that flushing of radium isotopes from the rock-mass and the dumps is not significant. Therefore, it can be concluded that uranium ore mining in the region of Kletno has not caused any significant radioactive contamination.