DEvelopment of COupled models and their VALidation against EXperiments

The DECOVALEX project is an international research and model comparison collaboration, initiated in 1992, for advancing the understanding and modeling of coupled thermo-hydro-mechanical-chemical (THMC) processes in geological systems. Prediction of these coupled effects is an essential part of the performance and safety assessment of geologic disposal systems for radioactive waste and spent nuclear fuel, and also for a range of sub-surface engineering activities. The project has been conducted by research teams supported by a large number of radioactive-waste-management organizations and regulatory authorities. Research teams work collaboratively on selected modeling cases, followed by comparative assessment of model results. This work has yielded in-depth knowledge of coupled THM and THMC processes associated with nuclear waste repositories and wider geo-engineering applications, as well as the suitability of numerical simulation models for quantitative analysis. More »

DECOVALEX-2023: The Current Project Phase (2020-2023)


DECOVALEX-2023 is the current and 8th project phase and runs from 2020 through 2023. Modeling teams from 17 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.

Layout of the CRQ in-situ experiment and cross-section plane at 15 m from the GCS drift wall where a fracture is expected.

Task A addresses both areas related to the fluid pressurization within the COx and its resulting fracturing. It will also contribute to a robustness demonstration that these processes will not occur at the repository scale. More »

Stage 3 (Lasgit): the Large scale gas injection test at the -420 m level in Äspö HRL.

Several concerns were raised in Task A D-2019 as some key features in the modelling of advective gas were still unclear. With these concerns in mind, development of new numerical representations for the quantitative treatment of gas in clay-based repository systems are therefore required, and are the primary focus of Task B under DECOVALEX-2023. More »

Figure 1: Schematic diagram of the FE tunnel.

The full-scale emplacement experiment (FE experiment) at the Mont Terri Underground Rock Laboratory was designed to replicate the emplacement tunnel of Nagra’s reference repository design at 1:1 scale. The focus will be to understand pore pressure development in the Opalinus Clay and how this is affected by heating, engineering factors (e.g. shotcrete, tunnel shape) and damage due to tunnel construction and thermal effects. More »

Schematic view of the Horonobe full scale in-situ EBS experiment

Full scale in situ Engineered Barrier System (EBS) experiments have been addressed in several phases of the DECOVALEX project where water infiltration into the buffer material after the emplacement was analyzed. The task being conducted here focuses on the incorporation of such buffer material density changes into the analysis codes. More »

Figure 1. BATS heated array and data acquisition systems

The primary Task E objective is to predict and quantify the importance of coupled THMC processes relating to the availability of heating, mechanical deformation, and water to flow into heated excavations in bedded salt. More »

Figure 2. Example of a flow and transport model domain with generic repository in fractured crystalline rock.

The primary objectives of Task F are to build confidence in the models, methods, and software used for performance assessment (PA) of deep geologic repositories, to bring to the fore additional research and development needed to improve PA methodologies, and to cultivate awareness of international PA practices among participating countries and teams. More »

Figure 1: Task G structure

The emphasis of this task is at the laboratory scale, using well-designed experiments to link micro-scale THM(C) effects acting on fracture surfaces and asperity contacts with emergent fracture properties such as permeability. More »

Current Partner Organizations

Logo Link Organization
link ANDRA
National Radioactive Waste Management Agency
link BASE
The Federal Office for the Safety of Nuclear Waste Management
link BGE
Federal Company for Radioactive Waste Disposal
link BGR
Federal Institute for Geosciences and Natural Resources
link CAS
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences
link CNSC
Canadian Nuclear Safety Commission
link COVRA
Centrale Organisatie Voor Radioactief Afval
link DOE
Department of Energy
Empresa Nacional de Residuos Radiactivos
link ENSI
Swiss Federal Nuclear Safety Inspectorate
link JAEA
Japan Atomic Energy Agency
link KAERI
Korea Atomic Energy Research Institute
Republic of Korea
link NWMO
Nuclear Waste Management Organization
link RWM
Radioactive Waste Management
link SSM
Swedish Radiation Safety Authority
link SURAO
Radioactive Waste Repository Authority
Czech Republic
link Taipower
Taiwan Power Company