The convection cooling system of the Yakutsk permafrost seed repository     

Vladimir N. Panin  Georgii P. Kuzmin 《寒旱区科学》2014,6(4):0309-0313

Temperature is critical to maintaining seed viability under long-term storage conditions. It has been common practice to use refrigeration systems to maintain required storage temperatures. A seed repository constructed in permafrost in Yakutsk, Russia is the first seed storage facility that relies solely on natural cold. This paper describes the design and performance of the cooling system of the repository. An innovative aspect of the cooling system is that it utilizes the patterns of temperature wave propagation in permafrost. Predicted and measured ground temperatures for the first year of operation are presented and analyzed. Results indicate that convection air cooling systems can be used to control the temperature regime in underground facilities in permafrost.  相似文献   

Effect of groundwater chemistry on the swelling behavior of a Ca-bentonite for deep geological repository     

《Physics and Chemistry of the Earth》2013

The swelling properties of buffer material for high level radioactive waste repository in a near-field environment are of particular importance for achieving the low permeability sealing function. In this study, the free swelling behavior of a potential buffer material Zhisin clay is evaluated under simulated groundwater conditions such as immersion in NaCl, CaCl₂, and Na₂SO₄ solutions at various concentrations. Experimental results indicate that Zhisin clay, being a Ca-bentonite, exhibits reduced swelling strain in salt solutions. The amount of decrease in swelling strain upon saline water intrusion is affected by both the type and concentration of electrolyte. At the same concentration, the swelling strains in CaCl₂ solution are lower than those in NaCl solution due to the quasi-crystals formed in the presence of calcium ions. Also, the swells in Na₂SO₄ solution are found to be lower than those in NaCl solution. This is attributed to the precipitation of CaSO₄, which acts as binding agent and results in aggregation of clay particles.  相似文献   

Thermo‐hydro‐mechanical modeling of damage in unsaturated porous media: Theoretical framework and numerical study of the EDZ     

C. Arson  B. Gatmiri 《国际地质力学数值与分析法杂志》2012,36(3):272-306

The damage model presented in this article (named ‘THHMD’ model) is dedicated to non‐isothermal unsaturated porous media. It is formulated by means of three independent strain state variables, which are the thermodynamic conjugates of net stress, suction and thermal stress. The damage variable is a second‐order tensor. Stress/strain relationships are derived from Helmholtz free energy, which is assumed to be the sum of damaged elastic potentials and ‘crack‐closure energies’. Damage is assumed to grow with tensile strains due to net stress, with pore shrinkage due to suction and with thermal dilatation. Specific conductivities are introduced to account for the effects of cracking on the intensification and on the orientation of liquid water and vapor flows. These conductivities depend on damage and internal length parameters. The mechanical aspects of the THHMD model are validated by comparing the results of a triaxial compression test with experimental measurements found in the literature. Parametric studies of damage are performed on three different heating problems related to nuclear waste disposals. Several types of loading and boundary conditions are investigated. The thermal damage potential is thoroughly studied. The THHMD model is expected to be a useful tool in the assessment of the Excavation Damaged Zone, especially in the vicinity of nuclear waste repositories. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

分布热源作用下裂隙岩体渗流-传热的拉氏变换-格林函数半解析计算方法   总被引：1，自引：0，他引：1  

项彦勇  郭家奇 《岩土力学》2011,32(2):333-340

以裂隙岩体高放射性核废物地下处置库性能评估为目标,提出了分布热源作用下单裂隙岩体渗流-传热的简化概念模型、控制微分方程和拉氏变换-格林函数半解析法,为进一步采用半解析法计算分布热源作用下多裂隙岩体的渗流-传热问题奠定了基础。针对单裂隙岩体的渗流-传热问题,建立考虑岩石内热源和二维热传导的控制微分方程,利用拉氏变换域微分方程的基本解建立格林函数积分方程,采用解析法处理其中的奇点,通过数值积分和拉氏数值逆变换求解,计算任意时刻裂隙水和岩石的温度分布。通过算例,与基于岩石一维热传导假定的解析解进行了对比,并计算分析了分布热源作用下单裂隙岩体的渗流-传热特征及其对裂隙开度、岩石热传导系数和热流集度的敏感度。算例表明,（1）就裂隙水温度而言,由于考虑了岩石的二维热传导,拉氏变换-格林函数半解析解小于基于岩石一维热传导假定的解析解;（2）裂隙水温度和岩石温度对裂隙开度和热流集度的敏感度较大,对岩石热传导系数的敏感度较小。  相似文献   

米尺度裂隙岩体模型水流-传热试验的数值模拟分析   总被引：1，自引：0，他引：1  

刘学艳  项彦勇 《岩土力学》2012,33(1):287-294

为了研究高放射性核废物地下处置库近场的水流-传热耦合问题,采用国内高放废物地下处置库预选场址--甘肃北山地区的花岗岩石块体,加工组合成米尺度的规则裂隙岩体模型,设置边界热源和裂隙水流,试验模拟裂隙水水流与传热之间的相互作用。作为该室内模型试验的前期理论研究,采用等效孔隙介质数值模型,着重分析了裂隙开度、裂隙流量和热源功率对流场和温度场的影响。在设定条件下,计算分析表明：热传导和裂隙水水流由热源作用初期的不耦合很快转化为耦合;不流动的裂隙水主要表现为热存储和热传导,而流动的裂隙水还引起流动传热和水与岩石之间的对流换热,使岩体温度场明显不同于单纯热传导的情况;如果保持裂隙水流量不变,则裂隙开度的变化对水流-传热影响不大;如果保持裂隙水流速不变,则裂隙开度的变化对水流-传热影响显著;热源功率越大,通过裂隙水的热流量越大,裂隙水压强越大,而当温度超过100 ℃时,裂隙水会因汽化而压强显著增大;加热7 d时,热量的输入和输出几乎相等,裂隙水流带走的热量接近热源供给的热量,模型系统基本达到了热平衡。  相似文献   

考虑膨胀效应UH模型的有限元实现     

张盼盼  罗汀  姚仰平 《岩土力学》2015,36(Z1):664-668

高庙子膨润土已被确定为我国高放废物地质处置的首选缓冲/回填材料,进行其力学特性及应用模拟研究对合理设计处置库具有十分重要的意义。考虑膨胀效应的UH模型是在超固结非饱和土本构模型（非饱和土UH模型）的基础上提出的,因引入了土体团粒的吸水膨胀作用,使其适用于非饱和膨润土。基于有限元软件ABAQUS的二次开发平台,利用Fortran语言编制模型的UMAT（user-difined material）材料子程序,进行了考虑膨胀效应UH模型的有限元实现。然后针对高放废物处置概念模型,利用编制的模型子程序对高放废物处置系统进行了三维有限元模拟,并对渗流场和应力场的演化规律进行了初步探究。模拟结果显示处置系统中膨润土的内应力增加,土体的稳定性较好,说明选择高庙子膨润土作为缓冲/回填材料的合理性,也同时验证了程序的正确性。  相似文献   

A multiple-code simulation study of the long-term EDZ evolution of geological nuclear waste repositories     

Jonny Rutqvist  Ann Bäckström  Masakazu Chijimatsu  Xia-Ting Feng  Peng-Zhi Pan  John Hudson  Lanru Jing  Akira Kobayashi  Tomofumi Koyama  Hee-Suk Lee  Xiao-Hua Huang  Mikael Rinne  Baotang Shen 《Environmental Geology》2009,57(6):1313-1324

This simulation study shows how widely different model approaches can be adapted to model the evolution of the excavation disturbed zone (EDZ) around a heated nuclear waste emplacement drift in fractured rock. The study includes modeling of coupled thermal-hydrological-mechanical (THM) processes, with simplified consideration of chemical coupling in terms of time-dependent strength degradation or subcritical crack growth. The different model approaches applied in this study include boundary element, finite element, finite difference, particle mechanics, and elasto-plastic cellular automata methods. The simulation results indicate that thermally induced differential stresses near the top of the emplacement drift may cause progressive failure and permeability changes during the first 100 years (i.e., after emplacement and drift closure). Moreover, the results indicate that time-dependent mechanical changes may play only a small role during the first 100 years of increasing temperature and thermal stress, whereas such time-dependency is insignificant after peak temperature, because of decreasing thermal stress.  相似文献   

花岗岩中高放废物地质处置库系统分析方法研究     

陈伟明  王驹  李云峰  金远新  赵宏刚 《国外铀金地质》2009,(3):160-166

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。  相似文献   

Uranium Behavior in the Process of Primary Pitchblende Ores Alteration by the Post‐ore Hydrothermal Solutions: An Application to Assessment of Uranium Migration from Underground Spent Nuclear Fuel Repositories     

Nikolay P. Laverov  Vasily I. Velichkin  Ai Fujiwara  Naotatsu Shikazono  Alexey P. Aleshin  Enver E. Asadulin  Vyacheslav N. Golubev  Tatiana L. Krylova  Alexander A. Pek  Igor V. Chernyshev 《Resource Geology》2009,59(4):342-358

It has been shown that the main uranium ore mineral, pitchblende (uranium dioxide), is a natural analog of synthetic uraninite (also uranium dioxide), which constitutes 96% of spent nuclear fuel (SNF). Geochronological studies of the U‐Pb isotope systems in unaltered pitchblende from the orebodies reveal that these systems remained completely closed over the entire period (approximately 135 Ma) since the formation of the deposits. The bulk of the primary uranium ores within the Streltsovskoye ore field was influenced to various degrees by post‐ore hydrothermal solutions that led to pitchblende spherulites being replaced by pseudomorphs of an amorphous phase with a U‐Si composition; this phase also re‐precipitated in veinlets proximal to the pitchblende pseudomorphs. A technique specially developed by the authors was used to carry out quantitative counts of the abundance of uranium minerals by calculating the uranium mass balance in one of the orebodies subjected to hydrothermal alteration. The calculations reveal minimal uranium loss from the orebody. Uranium liberated in the process of the pseudomorphic replacement of pitchblende was immediately fixed, in situ, in the newly formed coffinite‐like amorphous U‐Si phase as a result of the development of an efficient geochemical barrier that prevented the long‐distance migration of uranium. In assessing the long‐term safety of underground SNF repositories, the results of the present study give us confidence that SNF uraninite, in terms of the preservation of its integrity as a mineral phase, provides for the reliable long‐term isolation of uranium, transuranium elements, and fission products that are “sealed” in the uraninite matrix. In the case of the mineral transformation of the uraninite matrix by hydrothermal solutions, the liberated uranium would be efficiently immobilized by the newly formed amorphous U‐Si phase.  相似文献   

土地评估系统中知识库的设计与集成   总被引：3，自引：0，他引：3  

唐旭  胡石元  刘耀林 《武汉大学学报(信息科学版)》2004,29(5):433-437

针对土地评估系统中评估知识紧密结合模式和松散结合模式的缺点 ,采用评估知识库作为专题数据与程序的接口 ,对评估知识与数据实体的相互关系、评估知识分类、表达、存储以及系统集成模式进行了讨论  相似文献