2841.DXXX沁馨宾馆设计参考文献及文献翻译

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1、本科毕业设计（论文）外文翻译译文学生姓名： 院 （系）： 机械工程学院 专业班级： 1 指导教师： 完成日期： 20 年 月 日 Eur.J.Mineral2009,21,177-1912008年11月发布于网上 模型混凝土与膨润土屏障的相互作用摘要：在地球化学条件下，对混凝土膨润土界面进行了研究，预期用来作为高放射性废物库。来源于混凝土的碱性条件将会改变矿物的PH值和膨润土阳离子交换性能。被动运输地球化学模型CrunchFlow是用来模拟水泥砂浆接触压实膨润土柱实验，该实验在实验室内进行需要一年，保持在25和120。热力学数据和所涉及的矿物成分和性能已选定，在必要时要进行调整。与以前的工作相

2、比，最重要的改进是一个数据库包含蒙脱土的扩大公式，该数据库适用于FEBEX膨润土组成的实验测定。这使得可以配合与这种矿物相进行具体的阳离子交换。动力学速率变化规律已选定，并对温度进行评估，来预测系统在长期时间（105年）内的性能。结果预测随着时间和温度的不同分布，膨润土将以氢氧化物、沸石类、次生粘土矿物和水泥水化物阶段沉淀。在建模边界条件下，在长的时间量程内，使预测的结果发生改变没有很大的意义。预期膨润土屏障中重大的矿物学改变扩大，是为了离开混凝土界面几厘米，离开膨润土也不能改变它的屏障功能。关键词：膨润土 碱性羽流 反应交通建模 CrunchFlow 蒙脱土 混凝土 1、 绪论 许多国家认为

3、深高放射性废物的地质处理，要凭借多重屏障系统，以确保废物能够隔离105-106年。几个设计包括大量的混凝土（作为支撑和缓冲区）和一个粘土基础工程屏障系统（ESB等，由压实膨润土制造）该系统聚集在粘土岩或结晶基地岩石上。 从废物罐中发射的热脉冲峰值用临时表面的贮藏量(50-100年)还原。当前大多数仓库的设计限制罐膨润土界面的预期最高温度为100（比利亚尔，等，2006）。数百年后热脉冲衰减，很久之前，罐腐蚀而预期放射性核种被释放。典型尺寸为罐直径为0.90米，和膨润土包装的径向厚度为0.75米（ENRESA,1997年）。来源于波兰特水泥的混凝土孔隙水具有高碱性（超碱性条件下，PH13），并且

4、能够与膨润土屏障发生反应并改变膨润土屏障（奎瓦斯，等人，2002年；拉米雷斯等人，2002；萨维奇等人，2002年）。这些早期的混凝土孔隙水由K+（0.2-0.5M），Na+（0.05-0.2M）和OH-（0.3-0.7M）组成，这些离子将有扩散传送，如果这种材料在不饱和的条件下布设，还和能受到膨润土吸力的平流作用下传送。两个主要阶段在混凝土改变的过程中可以辨认出来，混凝土改变要归因于浸出孔隙水与外部空隙水的相互作用。一个早期的超碱性和相对短期阶段的特点是溶解的碱金属氢氧化物的初始PH值将控制在13-14的范围内。在这个阶段，膨润土改变的特点是分解。钠和钾沸石（例如，方沸石）分解出对混凝土有用

5、的钠离子和钾离子（可用性功能，鲍尔和范德维德，1999年；韦吉尔代拉等，2000年；拉米雷斯等人，2005年）。在第二碱性长期阶段，该系统缓冲是由羟钙石（氢氧化钙）溶解在pH至温度为25（瑞德等人，2001年；萨维奇等人，2002年，高雪等人，2004年）。钙离子是水泥砂浆浸出液的主要阳离子种类。在这种情况下，假定沸石代替水泥阶段，如硅酸钙水合物（C-S-H），这种物质在蚀变的膨润土地区。 其他学者（伯纳，1992年；泰勒，1997年）包括第三阶段，当羟钙石上的缓冲能力殆尽时，pH值下降到低于12.5。在这个阶段，C-S-H的不一致溶解的凝胶和其他混凝土阶段确定的pH的缓冲能力来源于混凝土的边

6、缘。运输建模这一领域的研究已经对膨润土泥岩屏障碱性羽的影响进行了未来数百年至数千年的预测（德文特等人，2001年；萨维奇等人，2002年；德文特等人，2004年；特拉伯等人，2004年；所来而托里霍等人，2005年；特拉伯及麻德，2008年）。然而，我们仍缺乏良好特性的实验室，用来测试、修改和扩大目前的热力学和动力学数据库，用来预测改变的反应，包括砂浆和粘土基础屏障的改变。在这项工作中，利用地球化学代码CrunchFlow(斯蒂菲尔,2006)进行了模拟仿真实验，首先，实验室模拟运输单元格的碱性溶液（氢氧化钠0.25M）在被迫通过水泥砂浆圆盘和压实膨润土柱。实验结果（弗纳德等人，2006）证明

7、了在建模研究中生成的次生矿物的实质。其次，一旦对动力学条件进行了评价，由岩石、混凝土、膨润土组成的系统进行长期的建模实验，相当于105年的演变。2、实验结果的总结渗流细胞实验，用氢氧化钠超碱性溶液0.25M（pH值为13.4），它模仿了沥滤了的水泥早期阶段的孔隙溶液。这种溶液被注入水泥砂浆压实膨润土柱中。采用高为0.7厘米，直径为5.5厘米的CEM-I普通波兰特水泥圆柱。这种水泥提供了一个氢氧化钙受控的系统，如果混凝土膨润土反应导致pH明显下降，它将会溶解。膨润土柱单轴压缩至1.4克每立方厘米,尺寸为2.2厘米高和7.0厘米的直径。实验期间，每月测试一次溢出水的组成成分，测试时间长达一年。一个

8、月和六个月的实验也进行着，来测试中间阶段的特征(费尔南德斯等人，2006年，详细说明了这一点)。该实验在25到120也获得了温度功能的转变程度。在高温（120）下，在地球化学演化的条件下，基于一出水成分的变化，系统的三个阶段可以分辨出来。第一阶段（1-2月）的特征是膨润土中的可溶性盐类浸出。在反应的头几个星期，溢出水中氯化物测量与初始浓度相比大幅度下降。在硫酸盐的条件下，取溢出水中样品进行测量分析，由于水泥砂浆中硫酸盐的分解导致测量值逐渐减少（对硫酸钙矾石和任何残余石膏及硬石膏）。第二阶段（2-6个月）受控于次生矿物的溶解与沉淀，与pH值逐渐从8增加到12有关，这要归因于C-S-H凝胶（钙四水

9、合物）与蒙脱石的反应（奎瓦斯等人，2006）。第二阶段的结果是为蒙脱石解散创造流体运移的优先途径。同时，一些粘土聚集体附在水泥化合物表面，在水泥砂浆与膨润土界面处。这些涂料块的孔隙度属中等规模，由此产生的外部表面积急剧减少。在第三阶段(6-12个月),一旦粘土聚集体被密封,碱性溶液能够流过这些途径,与最初的粘土相互作用,这与pH值增加到12.5有关，而且渗透系数是开始时120(5.571.5310-13m.s-1)时测量的两倍。 高温下获得的主要矿物转变是沸石类的形成（方沸石的形成可以通过X射线衍射和扫描电镜量化观察），在离界面第一毫米的地方，雪硅钙石的低Ca/Si比C-S-H晶体的沉淀。C-

10、S-H结晶的程度随着离界面的距离增加而减少。在低温（25）时，渗透系数随时间下降。这也降低了蚀变带的厚度。在25时，C-S-H凝胶的结晶和水镁石在水泥砂浆和粘土接触的地方堵住孔隙以防止溶液进入膨润土中。利用X射线衍射没有发现新的矿物的矿物学量化，但同一类型的阶段，在120时利用扫描电子显微镜可以观察到。C-S-H凝胶不结晶，而且展示了从纤维到含丰富钙涂料的不同形态。C-S-H凝胶的形态是在实验中采用的温度函数。这些实验的详细描述可以在费尔南德斯等人的描述中找到。膨润土中观察到的矿物转化，它的温度、pH值，改变厚度，如表一所示。3、建模工具及其基本假设 地球化学反应运输代码CrunchFlow（

11、斯蒂费尔，2006年），该GIMRT/OS3D代码（斯蒂费尔和薮崎，1996年；斯蒂费尔，2001年）被用来更新版本，在25和120进行模拟实验。该代码包含了矿物溶解/结晶的动力学处理。 运输被认为只在一定范围内，因为压力条件和系统设计保持优先选择柱的方向流动。平流、扩散和分散传输机制时都考虑到了。包括阳离子交换性能，和实验观察到的次生矿物在允许范围内进行矿物转变。柱中运输的概念设计如图一所示。必须做出一些假设，归因于代码的限制和运输和化学参数的不确定性，例如扩散系数，孔隙度、高温下矿物稳定性（C-S-H阶段）和反应中动力学的矿物沉淀/溶解率（萨维奇等人参与，2007年）。此外，实验测试表明，

12、该系统通过增加流速作为溶解和沉淀反应在120流量集中的结果，近似假定为一个恒定的平均流速。反馈中不包括孔隙率对透射率的预测变化（见讨论）。由于这些原因，通过建模工具所得的结果，必须在这一背景下，考虑几个案例，运用不同的反应模型。这将有助于评估模型的可靠性，通过与实验结果相比较。4、热力学与动力学的数据库FEBEX-蒙脱土，也被称为“La Serrata”膨润土（卡巴雷若罗卓荆，2005年出版）被插入到数据库作为一种矿物阶段。蒙脱土的主要成分是FEBEX膨润土,包含两级储层非均质性。首先，一点点的钾是结构性的固定这层附属部件（如高层电荷）（夸德罗斯和利纳雷斯，1995年）。实际上化学反应并不显著

13、，因为K+与复杂的交换不相关。其次,不同的阳离子交换 (主要是钙、镁、钠在合适的比例)通过交换反应将改变他们的在地球化学环境下的分布，因此也是碱性羽局部控制间隙水组成。蒙脱土在热力学数据库中建立的化学组成（钙、铯、钾、镁或是钠）是相对简单的，并不是与任何真正的成分都相匹配。卡玛等人(2000)实验得到了离子活动的产品(IAP)和蒙皂石在80的溶蚀速率方程和pH值为8.8的FEBEX改性产品。IAP的平均值为5.010-53，而且蒙脱石的解散方程已给出：考虑到平衡，能够logK-Temperature函数上的一点的值（logK1 = -52.3时，温度为80)。水的基础物质Al3+,H+,和Si

14、O2(液体)不得不被替换,而且蒙脱土的结构基础转变为）O10(OH)2，这样与数据库保持一致。没有铁物种都考虑在水相,因此所有包含在蒙脱土中的Fe3+转化为Al3+，以维持水相的平衡，这样使Al(OH)4的化学计量系数变为1.605。利用数据库和范特霍夫方程就可以得到铝离子和氢氧根离子，和logK在80时的转换反应：FEBEX-膨润土分解所得的新的logK为：最后，这个化学公式稍有改变，由拉米雷斯等人所确定的（2002年），而且该公式被桑切斯等人使用在膨润土的一个0.5毫米的小块上，这与实验研究的成分组成相符合。在0-300的范围内，即runchFlow模型的规定，logK-Temperatu

15、re函数是在类比蒙脱土-钙的函数归纳总结得来的。25时，logK=6.26，根据分解方程：5、结论该研究表明，膨润土屏障在碱性条件下的稳定性和化学性能的缓冲能力，将会在深的贮藏处发生。蒙脱土的分解率预计在长时间内（105年）会降低，当不考虑对流运输时，初始膨润土在接口附近的一小部分正在分解。次生矿物方沸石、水镁石、镁皂石和C-S-H阶段，这是一个紧密的阶段，是在实验室里观察模仿膨润土变更区域的沉淀。沸石类，C-S-H阶段，具有不同的钙/硅的比值，而且镁和硅酸盐在试验中被检测到，而且他们已被预测在对流的条件下在360天的运作过程中沉淀在模型中，在长时间内（105年）仅考虑扩散过程。这个系统的复杂

16、性已经被CrunchFlow数值模型捕捉。动力学的矿物溶解/沉淀应进一步约束,大量的矿物质,包括其依赖于超级碱性条件。应用地球化学模式的实施等主题所需要的基本性质和化学的耦合关系,还有特定粘土的过程，例如，阴离子的排除。但是,有一个基本知识的缺乏，即孔隙尺度的操作流程，和这些细节怎样去完善。长期模型的预测必须在基本假设的基础上进行评估。这样做的目的不是对混凝土膨润土界面反应性预测的有信心，而是为了约束与贮藏室位置有关的反应过程，并指出一些模型的局限性（地球化学代码和热力学/动力学数据库的性能）。良好运作的详细定量模型试验，将会发展地球化学编码和提高改善热力学和动力学数据库。Eur.J.Mine

17、ral.2009,21,177191Published online November 2008Modelling concrete interaction with a bentonite barrierRAUL FERNANDEZ1,*,JAIME CUEVAS2 and URS K.MADER11Institut fur Geologie,Universitat Bern,Baltzerstrasse 13,CH-3012 Bern,Switzerland*Corresponding author,e-mail:raul.fernandezgeo.unibe.ch2Departament

18、o Quimica Agricola,Geologiay Geoquimica,Facultad de Ciencias,Universidad Autonoma de Madrid,Campus Cantoblanco,28049 Madrid,SpainAbstract:The concretebentonite interface has been studied under the geochemical conditions expected in a repository for high-level radioactive waste.The alkaline condition

19、s emanating from concrete will modify the mineralogy,pH and cation exchange properties of bentonite.The reactive transport geochemical model CrunchFlow was used to simulate column experiments with cement mortar in contact with compacted bentonite carried out at laboratory scale for a period of one y

20、ear at 25 C and 120 C.The thermodynamic data and compositional properties of the minerals involved have been selected and adapted where necessary.An important improvement,compared with previous work,is the inclusion of an extended formula for montmorillonite in the database that fits the experimenta

21、lly determined composition of FEBEX bentonite,and this allowed to tie the exchangeable cations specifically to this mineral phase.Kinetic rate laws have been selected and evaluated at both temperatures to predict the system behaviour at long timescales(105years).Results predict the precipitation of

22、hydroxides,zeolites,secondary clay minerals and cement hydration phases in bentonite with different distributions as a function of time and temperature.The predicted alteration produced at long timescales is not very significant under the boundary conditions of the modelling.The expected extension o

23、f significant mineralogical changes in the bentonite barrier is in the order of a few centimetres from the concrete interface,leaving the bulk of the bentonite unchanged in its barrier function.Key-word :bentonite,alkaline plume,reactive tansporte modelling,CrunchFlow,montmorillonite,concrete1.Intro

24、ductionMany countries consider deep geological disposal for high-level radioactive waste,whereby a multiple-barrier system has to ensure waste isolation for 105106 years.Several designs include substantial amounts of concrete(for support and as a buffer)and a engineered barrier system(EBS,e.g.,made

25、from compacted bentonite)hosted in either claystone or crystalline basement rock .Hyper alkaline pore waters emanating from the outer concrete shell will interact both inward with the bentonite barrier surrounding the metal canisters,but also outward with the host rock environment.The peak of the th

26、ermal pulse emitted from the waste canister is reduced by interim surface storage(50100years).Most current repository designs limit the expected maximum temperature at the canisterbentonite interface to 100 C(Villar et al.,2006).The thermal pulse decays after a few 100 years,long before radionuclide

27、s are expected to be released as a result of canister corrosion.Typical dimensions are 0.90 m for canister diameter,and 0.75 m for the radialthickness of the bentonite overpack(ENRESA,1997).Concrete pore waters originating from a Portland cement have high alkalinity(hyper alkaline conditions,pH.13),

28、and are able to react with and modify the bentonite barrier(Cuevas et al.,2002;Ramirez et al.,2002;Savage et al.,2002).These early cement pore waters consist of K+(0.20.5 M),Na+(0.050.2 M)and OH-(0.30.7 M),that will be transported by diffusion and possibly by advection due to bentonite suction if th

29、is material is emplaced under unsaturated conditions.Two main stages have been distinguished during concrete alteration due to leaching and interaction with external porewater.A first hyper alkaline early and relatively short-term stage is characterized by the leaching of dissolved alkali hydroxides

30、 that will control the initial pHs in the range of 1314.During this stage,the alteration of bentonite is characterized by montmorillonite dissolution.Sodium and potassium zeolites(e.g.,analcime,phillipsite)are formed,as a function of the Na+or K+ availability from the concrete(Bauer&Velde,1999;Vigil

31、 de la Villa et al.,2001;Ramirez et al.,2005).In a second alkaline long-term stage,the system is buffered by the portlandite(Ca(OH)2)dissolution at pH12.5(measured at 25)(Read et al.,2001;Savage et al.,2002;Gaucher et al.,2004).Ca2+s the predominant cationic species in the leaching solution of the c

32、ement mortar.In this case,zeolites are replaced presumably by cement phases such as calcium silicate hydrates(CSH)in the altered bentonite region.Other authors(Berner,1992;Taylor,1997)include a third stage when the buffer capacity of portlandite is exhausted,and pH decreases to values below12.5.Duri

33、ng this stage the incongruent dissolution of CSH gels and other cement phases determine the pH buffering capacity from the concrete side.Reactive transport modelling studies in this specific field have been carried out predicting the alkaline plume effects on the bentonite and claystone barriers for

34、 the next hundreds to thousands of years(De Windt et al.,2001;Savage et al.,2002;De Windt et al.,2004;Gaucher et al.,2004;Mader&Traber,2004;Soler&Mader,2005;Traber&Mader,2008).There is,however, still a lack of well characterized laboratory studies to test, modify and enlarge present thermodynamic an

35、d kinetic databases that validate the predicted alteration reactions both,within the mortar and the clay-based barrier.In this work,the modelling simulations were carried out by using the geochemical code CrunchFlow(Steefel,2006),firstly,to simulate laboratory transport cell experiments where an alk

36、aline solution(NaOH 0.25 M)was forced to pass though a cement mortar disk and a compacted bentonite column.Experimental results(Fernandezet al.,2006)provided the identity of secondary minerals to work with in this modelling study.Secondly,once the kinetic conditions were evaluated,long-term modellin

37、g of the host rockconcretebentonite system was performed for 105years.2.Summary of experimental resultsPercolation cell experiments were performed with a hyper alkaline NaOH 0.25 M(pH 13.4)solution,which mimics the early stage of pore water of the leached cement.The solution was injected into the ce

38、ment mortarcompacted bentonite system.A cylindrical column of 0.7 cm height and 5.5 cm diameter of CEM-I Ordinary Portland Cement (OPC)was used.This cement provides a Ca(OH)2 dominated system which will be able to dissolve if concretebentonite reaction causes a significant pH decrease.The bentonite

39、column was uniaxially compacted to 1.4 g .cm-3(dry density)into the dimensions of 2.2 cm height and 7.0 cm diameter.The effluent composition was tested once a month during the experimental time up to one year.One-month and six-month experiments were also carried out to characterize intermediate stag

40、es(see Fernandez et al.,2006,for details).The experiments were performed at 25 and 120,to obtain the extent of transformations also as a function of temperature.At high temperature(120),three stages can be differentiated in the geochemical evolution of the system,based on changes in effluent composi

41、tion.The first stage (12 months)is characterized by the leaching of soluble salts initially contained in the bentonite.Chloride measured in the effluent decreases sharply from its initial concentration during the first weeks of reaction.In the case of sulfates,the analytical measurements taken in th

42、e effluent samples decrease gradually due to the dissolution of sulfate phases in the cement mortar(ettringite and any residual gypsum/anhydrite).The second stage(26 months)is dominated by dissolution/precipitation of sec-ondary minerals associated with a gradual pH increase from 8 to 12 due to the

43、CSH(Ca-Si-hydrate)montmorillonite reaction(Cuevas et al.,2006).As a result of this second stage,montmorillonite dissolves creating preferential pathways for fluid migration.At the same time,some clay aggregates become coated with cement hydration phases at the cement mortarbentonite interface.These

44、coatings blocks the porosity at the meso-scale( 500A) ,producing a drastic reduction of the external specific surface area.In a third stage(612 months),once clay aggregates have been sealed,the alkaline solution is able to flow through these pathways,scarcely interacting with the initial clay,associ

45、ated with a pH increase to 12.5 and an increase in the hydraulic conductivity to twice the value measured at 120 initially(5.571.5310-13m.s-1)The main mineralogical transformations obtained at high temperature are the formation of secondary Mgclays,the formation of zeolites(analcime could be quantif

46、ied by XRD and observed by SEM)and the precipitation of low Ca/Si ratio crystalline CSH of tobermorite-type in the first millimetres from the interface.The degree of crystallization of CSH decreased with the distance from the interface.At low temperature(25),the hydraulic conductivity decreases with

47、 time.This also reduces the thickness of the alteration zone.At 25,precipitation of CSH gels and brucite in the cement mortarclay contact plugged the pore space preventing the solution to get into the bentonite. No mineralogical quantification of new minerals could be identified by XRD,but the same

48、type of phases could be detected by SEM as observed at 120.CSH gels are not crystalline and show different morphologies,from fibrous to Ca-rich smooth coatings.The CSH morphology is a function of the temperature applied in the experiments.The detailed description of these experiments can be found in

49、 Fernandez et al.,2006.Mineralogical transformations observed in bentonite as a function of temperature,pH and altered thicknesses are shown in Table 1.3.Modelling tools and basic assumptionsThe geochemical reactive transport code CrunchFlow (Steefel,2006),the updated version of the GIMRT/OS3D code(

50、Steefel&Yabusaki,1996;Steefel,2001) was used to simulate the experiments carried out at 25 and 120.The code incorporates a kinetic treatment for mineral dissolution/precipitation.Transport was considered in one dimension only because pressure conditions and system design maintain the flow in the pre

51、ferential direction across the column. Advective,diffusive and dispersive transport mechanisms were taken into account.Cation exchange properties were included and mineralogical transformations were constrained to permit the formation of the secondary minerals observed experimentally.The conceptual

52、design of the reactive transport in the column is shown in Fig.1.Some assumptions had to be made due to the code limitations and uncertainties regarding transport and chemical parameters such as diffusion coefficients,accessible porosity,mineral stabilities at high temperatures(i.e.CSH phases)and ki

53、netic precipitation/dissolution rates for most of the minerals involved in the reactivity(Savageet al.,2007).Furthermore,the experimental tests suggest that the flow velocity through the system increased through focussing of flow as a result of the dissolution and precipitation reactions at 120,but

54、an averaged constant flow rate was assumed as an approximation.No feedback of predicted changing porosity on transmissivity was included(see discussion).For these reasons,results obtained by means of modelling tools must be interpreted within this context,considering several cases and using differen

55、t reactivities for each model.This will help to assess the degree of reliability of the models by comparison with the experimental results.4.Thermodynamic and kinetic databaseFEBEX-Montmorillonite,also known as bentonite fromLa Serrata(Caballero et al.,2005)was inserted into the database(datacom.dbs

56、)as a mineral phase.This database is an extended adaptation from the Lawrence Livermore llnl.dat(Wolery,1992)which incorporates,besides the thermodynamic properties,also a kinetic data block.Montmorillonite is the main component of FEBEX bentonite and contains heterogeneity at two levels.Firstly,a l

57、ittle bit of potassium is structurally fixed indicating the presence of an illitic accessory component(high layer charge)(Cuadros&Linares,1995).This fact is chemically not significant since K+ is not relevant in the exchangeable complex.Secondly,the different exchangeable cations (mainly calcium,mag

58、nesium and sodium in comparable proportions)will change their distributions by means of exchange reactions within the perturbed geochemical environment induced by the alkaline plume,and thus also locally control the porewater composition.The chemical composition of montmorillonite established in the

59、rmodynamic databases(Montmor-Ca,-Cs,-K,-Mg or-Na)is relatively simple and is not a proper match for any real composition.Cama et al.(2000)experimentally obtained the ion activity product(IAP)and the smectites dissolution rate equation at 80 and at a pH of 8.8 for FEBEX montmorillonite.The averaged v

60、alue obtained for the IAP was 5.0 10-53and the dissolution equation for the smectite was given as:Considering equilibrium,a single point on the log KTemperature function(log K1=52.3 at 80 )is obtained.The aqueous basis species Al3,H and SiO2(aq)had to be substituted,and also the structural basis of

61、montmorillonite was changed to O10(OH)2 to be consistent within the database.No Fe species were taken into account in the aqueous phase,so all Fe3 contained in montmorillonite was transformed to Al3 maintaining charge balance,which changed the stoichiometric coefficient to 1.605 forAl(OH)4Making use

62、 of the phreeqc.dat database and the vant Hoff equation it is possible to get the converted reactions in terms of Al3 and OH,and their log K at 80:The new log K for the dissolution of the FEBEX-Montmor is obtained as:Finally,the chemical formula was slightly changed to the one determined by Ramirez

63、et al.(2002)and used by Sanchez et al.(2006)for a bentonite fraction,0.5 mm,which matches the composition determined in the experimental case of this study.The log KTemperature function,in the range 0300,as required in CrunchFlow,was obtained by extrapolation in analogy to the Montmor-Ca function in

64、cluded in the llnl.dat database,obtaining a log K=6.26(at 25)，for the dissolution equation:5.ConclusionsThis study demonstrates and details the stability and geochemical buffer capacity of the bentonite barrier under the expected alkaline conditions that will occur in a deep repository.The montmorillonite dissolution rate is predicted to be slow at long timescales(105years)when no advective transport is considered,whereby only a small fraction of the initial bentonite near the interface is being dissolved.The secondary minerals analcim