Diffusion of corrosion agents through an engineered barrier system

许多国家正在研究安全储存用过的核燃料的长期解决办法。加拿大核废物管理组织 ** 选择的一种解决办法是使用位于地面以下几百米的深层地质 ** 处置库。DGRs将储存用过的燃料罐（UFC），周围有一个工程屏障系统（EBS），由铜涂层组成，作为腐蚀屏障和高度压实的膨润土（HCB），包围着UFC。六氯代苯在与水接触 ** 后会膨胀，因此可以密封储存库内的缝隙，并提供一种适度导热的 ** 介质。它还可以减缓地下水的渗透，并在 **UFC破裂时延缓放射性核素的移动。此外，六氯代苯可通过限制可能存在的微生物的空间和水的可用性来抑制容器附近的微生物活动。然而，硫化物的扩散可导致微生物影响的腐蚀（MIC），可能导致屏障的早期失效。拟议的研究将 ** 调查的因素，可以影响硫化物扩散到UFC表面。该项目将包括在一系列潜在处置库条件下进行的扩散 ** 实验，这些实验以加拿大目前的设计 ** 规格和对DGR条件的预测为基础。实验研究的结果将用于 ** 进一步扩展和验证三维计算机模型。由此产生的模型将能够进行参数研究，以完善和优化加拿大DGR的设计。这项研究的结果将 ** 确定可能导致更高腐蚀率的关键参数，从而改进西北气象组织的EBS** 设计，并为加拿大人提供一种安全和可持续的废核燃料处置方法。本研究 ** 将解决地下环境中腐蚀性物质通过工程屏障系统扩散的重要科学问题，还将提高预测建模能力，以 ** 加强赞助机构的长期DGR设计/性能标准。

Many countries are studying long-term solutions for safe storage of used nuclear fuel. One such solution,**selected by the Canadian Nuclear Waste Management Organization (NWMO), is the use of deep geological**repositories (DGRs) that would be located several hundred metres below ground level. DGRs would store used**fuel canisters (UFCs) surrounded by an engineered barrier system (EBS), composed of copper coatings to act as**a corrosion barrier and highly compacted bentonite (HCB) that surrounds the UFC. HCB swells upon contact**with water and can therefore seal gaps within the repository and provide a moderately thermally conductive**medium. It can also slow groundwater infiltration and retard the movement of radionuclides in the event of a**UFC breach. In addition, the HCB can suppress microbial activity near the container by restricting space and**water availability to microbes that may be present. However, diffusion of sulphide can result in microbially**influenced corrosion (MIC), potentially causing early failure of the barrier. The proposed research will**investigate the factors that can affect sulfide diffusion to the UFC surface. The project will include diffusion**experiments performed under a range of potential repository conditions, based on current Canadian design**specifications and predictions for DGR conditions. The results of the experimental studies will be used to**further expand and validate a three-dimensional computer model. The resulting model will be capable of**parametric studies to refine and optimize the design of the Canadian DGR. The results of this study will**identify key parameters that may result in higher corrosion rates, leading to a refinement of NWMO's EBS**design and providing Canadians with a safe and sustainable method of used nuclear fuel disposal. This study**will address significant scientific questions regarding diffusion of corrosive species through the engineered**barrier system in sub-surface environments, and will also enhance predictive modelling capabilities to**strengthen the sponsoring agency's long-term DGR design/performance criteria.