Underground radioactive waste repositories: assessment of post-closure safety under extreme events

地下放射性废物储存库：极端事件下关闭后安全性评估

• 批准号: RGPIN-2019-06371
• 负责人: Pietruszczak, Stanislaw
• 金额: $ 1.89万
• 依托单位: McMaster University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=738871
• 关键词: Underground; radioactive; waste; repositories; assessment

The proposed research is concerned with a long-term safety assessment of Deep Geological Repository (DGR) for low and intermediate-level nuclear waste. DGRs are being considered in many countries with a nuclear power production. Those include Switzerland, France, Sweden, USA, Germany, UK and Japan among others. The first project to enter the construction stage is Onkalo repository in Finland, which obtained regulatory approval in November 2015. In Canada the site-selection process is currently under way and the efforts have recently focused on argillaceous formations of southern Ontario (Cobourg limestone) as a possible location for DGR. The primary objective of this project is to examine the gaps in the existing approaches and to establish some new methodologies for evaluating post-closure safety of DGR constructed in argillaceous rocks. The study will include four major research themes, viz. (i) description of mechanical and hydraulic properties of Cobourg limestone; (ii) coupled hydro-mechanical analysis of flow in fractured media; (iii) case studies related to near field assessment of excavation damaged zone (EDZ), and (iv) evaluation of post-closure safety of DGR under extreme events. In part (i), the fundamental issue addressed will be a correlation between the strongly heterogeneous fabric of the limestone and its mechanical/hydraulic properties. The quantification of fabric will employ an explicit tensorial measure, based on stereology, that will provide an orientation dependent information. For hydraulic properties, the conductivity tensor will be defined as a function of geometry of the pore network and an evolution law will be postulated to correlate it with the stress field. In part (ii), the research on the coupled hydro-mechanical analysis of flow in fractured media will be conducted. A new formulation will be developed that incorporates an averaging of the field operators within the referential volume adjacent to macrocrack. The last two parts, i.e. (iii) and (iv), will deal with a numerical implementation and verification of the proposed approaches. The emphasis will be placed on assessing the long-term safety of DGR in case of extreme events, such as strong earthquakes as well as climatic changes, viz. glaciation and/or permafrost. The mechanical analysis will be supplemented by the assessment of the radionuclide transport times through the geosphere and the possibility of escape to the environment. The primary outcome of this project will be an enhanced understanding of the physico-mechanical processes associated with long-term underground storage of nuclear waste and development of reliable numerical procedures for assessing the safety margins in case of extreme events.

该研究涉及对中低放核废料深层地质处置库（DGR）的长期安全评估。许多有核电生产的国家正在考虑DGR。这些国家包括瑞士、法国、瑞典、美国、德国、英国和日本等。第一个进入建设阶段的项目是芬兰的Onkalo储存库，该项目于2015年11月获得监管部门的批准。在加拿大，选址过程目前正在进行中，最近的工作重点是安大略南部的泥质地层（科布尔石灰岩）作为DGR的可能地点。 本项目的主要目标是检查现有方法的差距，并建立一些新的方法来评估建造在泥质岩中的DGR关闭后的安全性。该研究将包括四个主要研究主题，即（i）科布尔石灰岩的力学和水力特性描述;（ii）裂隙介质中流动的耦合水力力学分析;（iii）与开挖破坏区（EDZ）近场评估相关的案例研究;以及（iv）极端事件下DGR关闭后安全性评估。在第（一）部分，解决的基本问题将是石灰岩的强异质结构和它的机械/水力性能之间的相关性。织物的量化将采用基于体视学的显式张量测量，其将提供取向相关信息。对于水力学性质，将电导率张量定义为孔隙网络几何形状的函数，并假定其演化规律与应力场相关。在第二部分中，将进行裂隙介质渗流的水力-力学耦合分析研究。将开发一种新的配方，它包括一个平均的参考体积内的宏裂纹附近的现场运营商。最后两部分，即（iii）和（iv），将处理所提出的方法的数值实现和验证。重点将放在评估在发生极端事件，如强震以及气候变化，即冰川作用和/或永久冻土时，DGR的长期安全性。将通过评估放射性核素通过地圈的迁移时间和逃逸到环境中的可能性来补充机械分析。 该项目的主要成果将是加深对与核废料长期地下储存有关的物理-机械过程的了解，并制定可靠的数值程序，以评估发生极端事件时的安全裕度。