DECOVALEX-2027 is the current and 9th project phase and runs from 2024 through 2027. Modeling teams from 18 international partner organizations participate in the comparative evaluation of seven modeling tasks involving complex field and/or laboratory experiments in the UK, Switzerland, Japan, France and Sweden. Together, these tasks address a wide range of relevant issues related to engineered and natural system behavior in argillaceous and crystalline host rocks.

The DECOVALEX Task SAFENET is dedicated to better understand fracture nucleation and evolution processes in crystalline rocks, with applications in nuclear waste management, but also in geothermal reservoir engineering.

This task focuses on the development and collaborative testing of new constitutive models for the long-term deformation/damage behaviour of argillaceous rocks. New models developed from microscopic observations and laboratory experiments are then applied to simulate gas injection tests performed on Opalinus Clay (OPA) in the laboratory and at the Mont Terri underground research facility.

The task seeks to simulate observed thermal-hydrogeological-mechanical (THM) responses observed in boreholes completed in bedded salt at WIPP.

The Sandwich experiment in Mont Terri includes a new Sandwich sealing system for repository shafts, which consists of sealing segments (DS) of bentonite and equipotential segments (ES) that are characterized by a higher hydraulic conductivity. The task will perform comparative modelling of the two experimental shafts and supporting laboratory data.

Task BaSiSS (Bentonite and Sand in Sealing Systems) aims to enhance the knowledge of the processes and mechanisms governing the hydromechanical performance of sealing systems.

The Fractured Rock Extrapolation, Suitability Criteria and Inflow Prediction (FRESCIP) Task is aimed to develop and test alternative modeling concepts/methodologies such as discrete fracture network (DFN) and channel network models (CNM), with a particular emphasis on conditional simulation based on the types of data that can realistically be expected at successive stages of repository construction.

Different approaches to studying natural analogues will be compared. From this collaborative effort, it is expected that a better understanding of the clay barrier system and near-field fractured rock will be achieved.

The performance assessment (PA) task of DECOVALEX-2027 involves comparison of the models and methods used in post-closure performance assessment of deep geologic repositories.