The assessment of long-term safety of a geological repository has to rely on a robust model of a spatial and temporal distribution of the safety relevant properties of bentonite. Thus developing predictive capabilities of the mechanical behaviour of bentonite buffers, seals and backfills are a common need for all radioactive waste management programs that use bentonite in one or more engineered barrier system (EBS) components.
START DATE: 1 June 2017 END DATE: 31 May 2022
Because of the complexity of the objectives networking at European level is key for the development of an integrated system understanding, skills, training and capabilities. The present project aims at the development of understanding fundamental processes that lead to material homogenisation as well as improved capabilities for numerical modelling. This will lead to a scientifically justified treatment of the involved processes in future safety assessments and license application for nuclear waste repositories. In earlier assessments of the long term performance of bentonite EBS, the mechanical evolution of the installed
bentonite was neglected and an “ideal” final state was optimistically assumed. Now that several European national programs are moving towards licensing, construction and operation of repositories, this assumption is no longer sufficient. In order to verify the performance of current designs for buffers, backfills, seals and plugs the following is planned:
- A well-documented and communicated collection of the available knowledge prior to the project
- Re-evaluation of large part of the existing database to extract the important information, to compile the qualitative and quantitative observations and to develop the conceptual understanding
- Enhanced, robust and practical numerical tools, firmly grounded on a good conceptual understanding, that have the required predictive capabilities concerning the behaviour of engineered barriers and seals
- A complete experimental database for the need of the assessment models
- Verified models based on experimental results from experiments in different scales
- Workshops dedicated to the mechanical issues in bentonite open to the scientific community
The Beacon project is needed for the pan-European aims at building confidence amongst regulators and stakeholders regarding the performance of safety barriers in a geological repository. It is also cost- and time-effective to progress development of understanding regarding bentonite behaviour in a collaborative manner, and the pooling / sharing of precedent information enhances efficiency of overall process. The goal is to verify the performance of current designs for buffers, backfills, seals and plugs. The overall driver for the project is the assessment cases that will be defined at the onset of the project (WP1). The quantitative models currently available are not fully able to represent all the complexities of the evolution of an installed bentonite. A substantial effort is needed to improve both the conceptual approaches and the numerical solutions in the current models (WP3). The updated/newly developed models need to be tested and verified using available data (WP5). There are some areas where fundamental data and the understanding of materials are incomplete. An efficient experimental programme will support model development and testing (WP4). There is already a large database from experiments performed within EC projects and national programmes, both laboratory and Underground Research Laboratory (URL) experiments. Many of the tests have been performed with other purposes in mind, but the results can be used in the Beacon project. The objective of WP2 is to collect the relevant information and process it to a level where it can be used in this project
