共查询到20条相似文献，搜索用时 562 毫秒
1.
富铯矿物及其在核废物地质处置上的意义 总被引：1，自引：0，他引：1
自然界中最常见的铯矿物主要有铯沸石、富铯的云母类矿物和富铯的绿柱石类矿物,它们产于稀有金属花岗岩和LCT(Lithium-Cesium-Tantalum)型稀有金属伟晶岩脉体的中心部位或围岩接触带附近,形成于初始富含铯和挥发组份、处于稳定构造环境且经过高度演化分异的原始花岗质岩浆.由于天然富铯矿物中铯含量一般可达15%,它们的合成相可作为核废料中放射性元素137Cs的前景载体相,而且富铯矿物各自的化学成分和结构等矿物学特征,对137Cs核废物载体相及相应的深埋藏地质环境的选择和载体相在不同地质环境下的行为预测都有较好的指导意义. 相似文献
2.
R. Jeff Serne 《Engineering Geology》1989,26(4):319-329
The effects of ionizing radiation on simple solution systems have been studied by computer simulations of radiolysis in salt brine and dilute groundwater. The codes assume a closed homogeneous solution system in which reactants and products cannot enter or leave the system and species cannot diffuse towards or away from the source of radiation. Radiolysis of simple dilute groundwaters appears to be rather insensitive to the expected range of pH, temperature, and pressure in repositories. It is unclear whether this conclusion also holds for salt brine.
The waste-package environment is much more complex than systems that have typically been studied in the past. None of the conceptual models account for potential interactions with the solids present in the waste-package and host rocks. This limitation results primarily from a lack of data and the currént restriction to homogeneous (solution only) reactions. Because the rocks and waste-package materials are the primary pH, Eh, and chemical buffers in the system, radiolysis experiments that neglect their presence cannot definitively address the expected influence of radiation on solution chemistry.
Experimental evidence suggests that radiolysis will not cause significant changes in waste-form leaching, or significant degradation in the physical stability of clays, crystalline host rock, and packing materials. However, experiments in salt suggest that irradiation and heat could produce corrosive species that might affect canister corrosion and waste-form leaching. The possibility of enhanced container corrosion resulting from nitric acid formation in the moist air of an unsaturated tuff repository also warrants attention. 相似文献
3.
Celestina Adu-Wusu Ernest K. Yanful Lisa Lanteigne Mike O’Kane 《Geotechnical and Geological Engineering》2007,25(2):215-237
Soil cover systems are widely used for containment of municipal solid waste, hazardous and mine waste, with the objective
of limiting the ingress of precipitation and oxygen. The ability to predict their long-term performance is crucial, as their
failure would result in the release of contaminants to the environment. However, monitoring covers over the long term to derive
the information needed to aid in design is impractical and there are no large-scale covers that have been in use for a long
enough period to generate the data needed. Numerical models have been particularly useful as design tools. To improve their
reliability these models may be calibrated to field data and then used to make long-term predictions of cover performance.
The field performance of two resistive test soil covers on a 20% sloping waste rock platform is predicted using the two-dimensional
soil–atmosphere model Vadose/W. Input data for the model included soil, climate and vegetation data obtained either in the
field or laboratory. Model results were compared to field data to assess the validity of the program. The model reasonably
simulated field response patterns for soil water storage and suction. Divergence between field performance data and model
predictions were significantly influenced by snowmelt, interflow and flow through preferential pathways. 相似文献
4.
Experiments have been performed to study the thermal performance of a backfilled disposal vault in which the waste containers are emplaced in boreholes and surrounded by a bentonitesand buffer.
The near-field thermal regime in a buffer-backfill disposal vault in which the nuclear fuel waste is emplaced in canisters, is studied by one-eight scale experimental models. The thermal performance of the buffer and backfill are examined in a thermal drying environment prior to the ground water recharge of the disposal vault.
The formation of shrinkage cracks in the buffer due to drying and the response of these shrinkage cracks to the rewetting condition and their influence on the near-field thermal regime are assessed. 相似文献
5.
The study of the complex geomechanical interactions that take place within a borehole environment of a nuclear-waste disposal vault is crucial to the long-term safety and efficiency of a waste emplacement scheme. This paper presents a theoretical investigation of the interaction between a container shell and the surrounding buffer region which can be induced by discontinuous movement at a fracture plane which intersects a disposal vault borehole. The theoretical studies presented in the paper illustrate the influence of factors such as the mechanical properties of the buffer, surcharge loads on the surface of the buffer, and characteristics of the buffer-container and buffer-rock interfaces, on the stresses that are generated in the container. 相似文献
6.
《Applied Geochemistry》1995,10(4):477-487
The study of natural analogues is often used to support long-term predictions of the safety of geological disposal of used nuclear fuel. The case of a bronze cannon, submerged in seawater-saturated clay sediments for a period of 310 a, is reassessed with reference to a corrosion mechanism developed for copper nuclear waste containers in a conceptual disposal vault in the Canadian Shield. Redox reactions between Cu, Fe and dissolved O2 are believed to have played an important role in the corrosion of the bronze cannon and also form an essential part of the corrosion mechanism proposed for nuclear waste containers. Limited rates of mass transport through compacted clay are also important in determining the corrosion behaviour of both the cannon and the containers. 相似文献
7.
螺旋地桩具有施工便捷、进度快、环境影响小等优点,在地面光伏支架基础中逐渐得到推广应用,但其在腐蚀性土壤中易产生腐蚀破坏,影响使用寿命,尤其在盐渍土中更为突出。通过回顾螺旋地桩的腐蚀机理及影响因素,结合西北盐渍土地区某光伏电站地桩的腐蚀实例,在对腐蚀事故的现状调查、数值模拟及原因分析的基础上,根据腐蚀受损程度的不同,分别提出了不同的处理方案,并从桩身材料、保护层、改善受力性能、外加电流等方面提出了相应的措施。腐蚀事故的分析及处理的过程,能够为同类工程的设计、鉴定及处理提供借鉴和吸取教训。 相似文献
8.
A.P.S. Selvadurai 《Engineering Geology》1990,28(3-4):325-335
The bentonite-sand buffer material, which isolates the nuclear-fuel waste containers from the host rock mass, is a vital component of the multiple engineered barrier scheme advocated by the Canadian Nuclear Fuel Waste Management Program. This paper presents results of laboratory investigations which examine the influence of the container surface temperatures on the moisture migration within a compacted buffer in a borehole environment. 相似文献
9.
针对笔者开发的双重孔隙-裂隙介质热-水-应力（T-H-M）耦合二维有限元分析程序中使用的应力腐蚀和压力溶解模型,引入水饱和度修正因子。以一个假设的位于含水地层中的高放废物地质处置模型,拟定3种初始裂隙水饱和度的计算工况（Sw20=1.0、0.8、0.2）进行热-水-应力耦合的数值模拟,考察岩体中的温度、裂隙开度的闭合速率、闭合量、孔(裂)隙水压力、地下水流速和应力的变化、分布等情况。结果显示,随着初始裂隙水饱和度的由高值到低值,应力腐蚀和压力溶解产生的闭合速率从大变小,裂隙开度由初始值趋于残余值,粗糙面接触率由初始值趋于其名义接触率的时间也增加,裂纹应力强度因子的下降亦变慢;近场的裂（孔）隙水压力的变化、分布及其流速矢量场的形态有明显的不同;3种工况的岩体中的应力量值及分布的差别不大。 相似文献
10.
The challenge of peripheral ports: an Asian perspective 总被引：3，自引：0，他引：3
The growth of ports peripheral to the dominant container hubs has been well documented in North America and Europe, and has led to the elaboration of several theoretical models. This paper applies these models to the situation in South East Asia where much of the growth in containerisation is taking place. While confirming the emergence of several peripheral ports that are mounting challenges to the major hubs, we demonstrate that the factors behind the challenges are different to those postulated in the literature. Issues of governance arising out of the complex restructuring of the global ports industry are singled out. We suggest that a new geography of container terminals based on management and operational strategies of private and public bodies involved in the port industry needs to be fashioned. 相似文献
11.
Net-pen aquaculture results in the introduction of excess fish food and fecal matter in coastal waters. These wastes may modify the benthic environment. Mathematical models are developed in this study to simulate tidal and wind-driven currents, waves, and the resulting dispersion of fish food and fecal matter in coastal Maine, a region where limited modelling studies have been performed. Cobscook Bay and Toothacher Bay in Maine are studied in detail through the use of mathematical models and field data. We find that a systematic, site-specific, step-by-step modeling strategy involving the use of numerical models to simulate the overall hydrodynamic environment in combination with a waste-particle transport model can be an extremely powerful method of determining a priori whether aquaculture operations will cause high rates of net-pen waste accumulation at a particular site. 相似文献
12.
13.
Comparative study of municipal solid waste treatment technologies using life cycle assessment method 总被引：8，自引：8，他引：0
The aim of the study is to analyze three different waste treatment technologies by life cycle assessment tool. Sanitary Landfill, Incineration and gasification-pyrolysis of the waste treatment technologies are studied in SimaPro software based on input-output materials flow. SimaPro software has been applied for analyzing environmental burden by different impact categories. All technologies are favorable to abiotic and ozone layer depletion due to energy recovery from the waste treatment facilities. Sanitary landfill has the significantly lower environmental impact among other thermal treatment while gases are used for fuel with control emission environment. However, sanitary landfill has significant impact on photochemical oxidation, global warming and acidification. Among thermal technology, pyrolysis-gasification is comparatively more favorable to environment than incineration in global warming, acidification, eutrophication and eco-toxicity categories. Landfill with energy recovery facilities is environmentally favorable. However, due to large land requirement, difficult emission control system and long time span, restriction on land filling is applying more in the developed countries. Pyrolysis-gasification is more environmental friendly technology than incineration due to higher energy recovery efficiency. Life cycle assessment is an effective tool to analyze waste treatment technology based on environmental performances. 相似文献
14.
15.
夏季不同土地利用方式下的溶蚀作用研究——以重庆青木关岩溶槽谷区为例 总被引：3，自引：1，他引：2
土壤理化性质会随土地利用方式的不同而产生一系列的变化,从而影响到岩溶作用的方向和强度。通过野外溶蚀试片法,测得重庆青木关典型岩溶槽谷区6种典型土地利用方式下6个测试点夏季绝对溶蚀量和单位面积溶蚀量。结果表明,不同土地利用方式土下溶蚀速率存在显著差异,旱地>退耕林>水田>杉竹混交林>荒草地>竹林。对不同土地利用方式的不同层位溶蚀量进行统计发现:溶蚀速率基本上随深度增加而增大,但差别不大。但同一土地利用方式不同层位之间溶蚀量存在明显差别,差别最大点出现在荒草地,其壤中-20cm处溶蚀量是其表层的4.23倍。另外,各点壤中CO2含量随深度增加而增大,与溶蚀速率的变化总趋势有较好的对应关系。而土壤有机质则均随深度的增加而减少,与溶蚀速率变化总趋势相反,但与地表溶蚀速率基本成正相关。故认为有机质含量对溶蚀速率的作用机制较为复杂。 相似文献
16.
17.
18.
Scott A. Wood 《Engineering Geology》1993,34(3-4):229-259
The mobility of the rare-earth elements (REE) is relevant to nuclear waste management in that REE are produced during radioactive decay in high-level waste and they are good chemical analogues for some of the trivalent actinides (e.g., Am3+ and Cm3+). Car☐ylic acids are present naturally in many geologic fluids and also have been disposed of along with radionuclides; such complexing agents may increase the mobility of the REE (actinides) and need to be considered in geochemical models of the transport of these metals into the far-field environment. In this study, available stability constants for the formation of REE complexes with the organic ligands acetate, adipate, benzoate, citrate, ETDA, formate, fumarate, glutarate, glycolate, -hydroxyisobutyrate, isobutyrate, lactate, maleate, malonate, -mercaptoacetate, oxalate, m-phthalate, o-phthalate, propionate, salicylate and succinate have been critically evaluated. Those stability constants considered most reliable were, where necessary, corrected to 25°C using published enthalpy data and, where possible, corrected to infinite dilution using a model based on the Pitzer equations. These data provide the basis for future geochemical modelling of the behavior of the REE in nuclear waste disposal sites. Some simple geochemical calculations presented in this paper suggest that monodentate ligands such as acetate are unlikely to contribute significantly to REE (actinide) mobility in most nuclear waste disposal environments. However, ligands capable of chelating in a multi-dentate manner, e.g., oxalate, malonate, succinate, EDTA, etc., may increase the mobility of trivalent lanthanides and actinides significantly, even though their concentrations are lower than monodentate ligands in most natural environments. However, the effectiveness of any of these organic ligands depends on the concentrations of competing ions, such as Ca2+, Mg2+, etc., being low relative to the total ligand concentration. 相似文献
19.
Environmental applications of magnetometry profiling 总被引：1，自引：0，他引：1
Environmental impact assessment is currently a standard procedure for assessing the possible consequences of any particular activity that may cause degradation of the environment. Magnetometry profiling, which involves accurate measurements of the Earth's magnetic field at closely spaced stations is a technique that has a large number of environmental applications that can greatly improve this assessment. The technique has been applied successfully for waste disposal site evaluation, toxic waste detection, assessment of the quality of roadstone before excavations and can provide information that allows subsurface water movement models to be refined. Magnetometry profiling is inexpensive, nondestructive, and a very costeffective method of acquiring useful information about the environment. 相似文献
20.
Characterising and modelling the excavation damaged zone in crystalline rock in the context of radioactive waste disposal 总被引：3，自引：0，他引：3
John A. Hudson A. Bäckström J. Rutqvist L. Jing T. Backers M. Chijimatsu R. Christiansson X.-T. Feng A. Kobayashi T. Koyama H.-S. Lee I. Neretnieks P.-Z. Pan M. Rinne B.-T. Shen 《Environmental Geology》2009,57(6):1275-1297
This paper describes current knowledge about the nature of and potential for thermo–hydro–mechanical–chemical modelling of the excavation damaged zone (EDZ) around the excavations for an underground radioactive waste repository. In the first part of the paper, the disturbances associated with excavation are explained, together with reviews of Workshops that have been held on the subject. In the second part of the paper, the results of a DECOVALEX [DEmonstration of COupled models and their VALidation against EXperiment: research funded by an international consortium of radioactive waste regulators and implementers (http://www.decovalex.com)] research programme on modelling the EDZ are presented. Four research teams used four different models to simulate the complete stress–strain curve for Avro granite from the Swedish Äspö Hard Rock Laboratory. Subsequent research extended the work to computer simulation of the evolution of the repository using a ‘wall-block model’ and a ‘near-field model’. This included assessing the evolution of stress, failure and permeability and time-dependent effects during repository evolution. As discussed, all the computer models are well suited to sensitivity studies for evaluating the influence of their respective supporting parameters on the complete stress–strain curve for rock and for modelling the EDZ. 相似文献