HAE放射性废物预选处置场地地下水运动特征及核素～（90）Sr迁移行为研究

【作者】 王青海；

【导师】 王兰生； 喻名德；

【作者基本信息】 成都理工大学 ， 地质工程， 2002， 博士

【摘要】 放射性核素在地下水中的迁移行为研究是放射性废物地质处置过程中的一个重点研究内容，同时也是处置场安全评价的关键问题之一。由于基岩介质分布范围广、孔隙度低、力学强度高等优点，从二十世纪七十年代对放射性废物进行规范性地质处置以来，世界上大多数的放射性地质处置库都建在或规划建在基岩中。但是由于在基岩中往往存在断层、节理，它们是核素向环境迁移的主要通道。核废物在基岩介质中进行处置是否可以确保安全，在相当程度上取决于裂隙岩体对核素的屏障性能和作为核素迁移载体的基岩裂隙水的运动特征。因此，研究核素在基岩裂隙水中的迁移问题，具有重要的意义，但由于自然界中基岩裂隙分布的复杂性，因此它又是一个难度比较大的问题。 在西部大开发和注重环境保护的环境下，对我国西北HAE放射性废物尽快进行地质处置是国家十分关心的一件事。本论文作为HAE放射性废物地质处置安全评价研究的一个子课题，对以基岩介质为围岩的HAE预选处置场地开展基岩裂隙水运动特征研究，并在此基础上对重点关心的高毒性核素⁹⁰Sr在基岩裂隙水中的迁移行为进行了系统的探索，重点预测处置库破坏后核素⁹⁰Sr对HAE处置场地唯一水井——3号水井的污染程度。其研究内容包括以下几个方面： （1）通过对我国HAE预选处置场丰富地质资料的大量统计和分析，建立了该处置场的基岩裂隙渗透模型。再根据HAE预选处置场基岩裂隙水的补给、径流、排泄条件及水位动态特征，建立了预选处置场基岩裂隙水水运动模型。 （2）对高毒性锶元素在我国HAE预选处置场地下水中的化学行为和迁移参数进行系统的研究，其中主要包括 ①运用热力学方法分析了锶元素在地下水中的存在形态， ②利用理论分析与实验测试相结合的方法分析了花岗岩和砂岩对核素锶的吸附机制， ③采用室内实验装置研究了核素锶在地下水中的扩散参数以及在花岗岩和砂岩中的本征扩散参数， ④采用静态批式法研究了锶在砂岩和花岗岩中的分配系数。 （3）建立了锶在HAE预选处置场基岩裂隙饱水带中的迁移模型。利用该模型对各种可能环境下核素锶进入地下水后的迁移行为进行模拟和预测。 本项研究工作的难点和关键问题有三个：HAE处置场基岩裂隙系统中，导水裂隙的优势方位是什么，基岩裂隙水活跃带分布情况如何；怎么对核素迁移的复杂化学行为进行实验室测试并取得有关定量化参数；怎样数值化表现出溶质的迁移行为和污染情况 本论文在解决以上三个问题上做了大量的工作，达到了预期的目的，其创新之处有以下三点： （1）通过地质资料的分析，首次提出了HAE预选处置场基岩裂隙导水的优势方位和基岩裂隙水活跃带的大致分布特征。它是一个很重要的基础性研究成果，是建立HAE处置场水运动模型的前提。 （2）采用理论分析和自己设计的室内实验装置，较系统地研究了核素锯在水中的迁移参数。为核素锯在地下水中的溶质迁移模型建立以及迁移模型的预测提供了所需的定量化参数。一 门)首次将 Chunmiao Zheng等专家编的国际上比较权威的溶质运移计算软件－－。df1o。软件成功地运用到放射性废物处置的环境评价领域。三维动态模拟锯进入裂隙饱水带后的污染范围、污染浓度分布及其随时间的变化规律，确定了Xr的污染区域。 （4）综合的模拟评价结果表明，在HAE处置场处置放射性废物，不会对3号水井和地下水下游地区——阿根布拉克洼地及其更远的地下水域造成不利的后果。认为HAE预选处置场是进行低中放废物地质处置的一个理想场地， 本论文的研究成果从环境评价的角度为上层领导的HAE放射性废物处置场选址决策提供了科学的依据，具有一定的实际意义和理论价值。更多还原

【Abstract】 The behavior of the radio nuclides transportation in groundwater is a focal point in the course of disposing radioactive waste underground, and it also is one of the key problems about the environment evaluation of HAE waste disposal field. Because of wide distribution and low porosity and high mechanics strength, most of radio nuclide waste warehouses in the world are built or are going to built in bedrock since the standard program about radioactive waste disposing carried in the 1970s. But faults and joints are often found in bedrock, which are the major channels the nuclides moved to the outer environment. So it is important to study the nuclide transportation in the groundwater, however this study is a difficult problem because the fracture distribution in bedrock is complex in nature.Under the environment of the developing the West part of China and the protecting the natural environment, our government cares much about the radioactive waste disposition which is the product of some nuclear test. As a subject about the environment evaluation of HAE field, this paper mainly researches the characteristic of the fracture water moving in the bedrock fractures in HAE field, and studies the element ’"Sr which is a high toxicity nuclide transportation in fracture water, and predicts the pollution effect of the element ^Sr to well 3 which is a sole well in the HAE region when radioactive waste warehouse is destructed sometime in future. The contents of this paper include the following several aspects:(1) A model of the fractures leakage is built through counting and analyzing the wealthy geological records of HAE field, and a model of the fracture water transporting is also built according to the fracture water condition of its recharge and its runoff and its discharge in HAE field;(2) This paper studies the chemical behavior and the migration parameters of the elenent Sr2+ in ground water in HAE field, the main contents include:①The presence form of the element Sr in ground water is analyzed by way of the rmodynamics;②The absorption mechanism that granite and sand stone absorbs Sr element is analyzed based on theory and experiment test③The diffusion parameters of the element Sr in water and in granite and in sand stone are researched with laboratory experiment test;④The partition coefficient of sand stone and granite to Sr is tested by the batch way.(3) this paper builds a model of the transportation of the element 90Sr in the fracture water in HAE field. With this model, this paper models and predicts the transportation of the element 90Sr in the fracture water in HAE field under various circumstances when the HAE radioactive waste warehouse is undermined.There are three difficulties and key problems in this papaer: :the first problem is what is the dominance bearing of the leakage fractures, and how the bedrock fracture water distribute, the second is how to test the complex chemical behavior in experiment way and quantify the relative parameters, the last question is how to number the transportation of the element 90Sr and its pollutionTo solve the three problems, this paper does lots of work and come to the prospective order, the creativities in this thesis as follow:(1) The dominance bearing of the leakage fractures and the distribution feature of the fracture water are ascertained based on rich geological data ,These basal researches are very important ,which are the premises to build the transport model of the fracture water in HAE field.(2) This paper test the migration parameters of the element Srsystematically by theory and the experiment set designed by self ,it provide theon quantification parameters that the migration model of the element Sr in thefracture water in HAE field. .(3) The software MODFLOW is a authority software in the world edited by professors Chunmiao Zheng etc, this paper uses the software successfully to model the pollution area and pollution concentration of the element 90Sr in fracture water in HAE更多还原