This contribution focuses on the numerical assesment of the barrier integrity of a generic nuclear repository in crytalline rock.

The assessment of the integrity of the geological barrier for repositories for nuclear waste can be significantly influenced by uncertainties in the model inputs. Hence, the results of these established integrity analyses should be enriched by statistical information. In this contribution, we present preliminary probabilistic results for rock integrity assessment for the generic repository system in clay rock and the developed tools for stochastic analyses.

In the AREHS project, the effect of the alternation of cold and warm periods over 1 million years on the hydrogeological system in the vicinity of a repository was simulated. This was done with thermal–hydraulic–mechanical (–chemical) simulations. The simulations were implemented for generic 3D models for all three host rock formations: clay rock, salt rock and crystalline rock. In addition to the results for the generic sites, a workflow was developed that can be applied to concrete sites.

This contribution aims at showing the basic, practical steps for numerical modeling with focus on the preparation and interpretation of the models and results, e.g. model calibration, verification and validation. We study the Opalinus Clay and perform laboratory and field scale simulations related to nearly the same mechanism, e.g. drying/wetting, shrinkage/swelling and cracking. We simulate the long-term Cyclic Deformation (CD-A) experiment in the Mont Terri Rock Laboratory.

We try to assess the integrity of storage sites for nuclear waste in case of an earthquake, particularly for sites in crystalline rocks, such as granite.

In the framework of the Site Selection Act – StandAG, the geoscientific and planning requirements and criteria for the site selection for a repository for high-active nuclear waste are specified. This includes, among others, the modelling of hydrogeological scenarios such as how future cold and warm periods and associated glaciation events can change the (petro-)physical properties as well as the natural hydrogeological properties of the overall system which is the focus of the AREHS project.

The Federal Institute for Geosciences and Natural Resources (BGR) performs experiments in the Swiss Mont Terri rock laboratory to obtain a comprehensive understanding of the evolution of a repository. Activities and results by BGR from actual and still ongoing experiments are presented exemplarily focusing on main aspects regarding the behaviour of underground facilities. BGR's focus lies mainly on aspects of the construction, post-closure transient, and partly post-closure equilibrium phases.