Thoroughly examining all aspects of the safety and technical feasibility of geological disposal in a deep clay layer requires a great many experiments, many of which are carried out in the HADES underground research laboratory.

The diagram below gives an overview of past and present experiments conducted by EIG EURIDICE, both above and below ground, and of all the other experiments that have been set up in HADES.


Some experiments started more than 25 years ago. This means that the models developed to describe how a disposal system evolves over time can be compared against actual changes and fine-tuned if necessary. Since HADES is a licensed nuclear facility, a wide range of radioactive tracers and sources may be used there, making it a unique underground research tool.

From small and simple to large and complex

A number of relatively simple experiments are designed to examine one specific aspect or process of the disposal system. This gives researchers an opportunity to study and understand the different properties and processes that are important for assessing the safety and technical feasibility of a waste repository. For the ATLAS experiment, for instance, a heat source and measuring instruments have been introduced into the clay in order to determine the thermal conductivity of the Boom Clay host rock. It is important to have this information because some of the waste will still produce a certain amount of heat after being placed in the disposal galleries. Researchers can then calculate how high the temperature in the clay will rise.

In the case of integrated experiments, several of these aspects are combined in a single experiment with the aim of approximating the complex actual conditions of a waste repository as closely as possible. This enables scientists to study the interaction between specific phenomena, like those expected to occur in a repository. CORALUS is an example of an experiment investigating the combined effect of heat and radiation on the stability of the glass matrix for vitrified waste.

Lastly, large-scale demonstration tests make it possible to ascertain the safety and feasibility of a waste repository on a scale that approximates the actual conditions encountered in a real repository. They can also be used to confirm the results of small-scale experiments and to fine-tune the predictive models developed on the basis of these findings. This means that a reliable assessment of the long-term safety of a repository can be made. In the PRACLAY experiment, for example, the expected heat output in a disposal gallery is being simulated by heating a 30-metre section of the PRACLAY gallery for 10 years and studying the thermal impact on the surrounding clay and the gallery lining.

European context

The European Commission has played a crucial part in the development and implementation of a great many experiments and tests. The experiments and projects that have benefited from EU support, within the R&D Framework Programmes, are marked with a European flag in the list shown below. In some cases, the project phase has ended but the measurement data are still being monitored or the experimental set-ups are being re-used as part of the Belgian research programme on geological disposal.



ARCHIMEDE EC   1991-1995    

Study of pore water chemistry of Boom Clay

ATLAS I, II, III, IV     1992-present  

Study of hydro-mechanical properties of clay when subjected to heat

BACCHUS I, II EC   1988-1995  

Study of clay as a backfill material

CACTUS I, II EC   1990-1994  

Study of hydro-mechanical properties of clay when subjected to heat

CERBERUS     1985-1999  

Effect of radiation, heat and mechanical disturbance on hydro-chemical properties of clay

CLIPEX     1997-2003  

Monitoring of hydro-mechanical response to excavation of the Connecting gallery

CORALUS I, II, III, IV     1997-present  

Research on the stability of the glass matrix under realistic disposal conditions, in the presence of a heat source and radiation

CONNECTING GALLERY           2001-2002  

Construction of a gallery on an industrial scale, using a tunnelling machine

CORROSION     1985-1997  

Experiments to test the deterioration (corrosion) of different waste packaging materials in contact with clay

ESDRED EC   2004-2009  

Repository design studies

FORGE EC   2011-present  

Research on gas migration in the excavation-damaged zone

MEGAS EC   1992-1996  

Study of gas formation and migration of gas in clay

MIGRATION     1988-present  

Experiments to study the dispersion (migration) of radioactive substances in clay

MINE-BY-TEST     1984-2002  

Construction of a shaft and gallery in unfrozen clay

MODERN EC   2009-2013  

Development of a monitoring strategy and testing of monitoring sensors

MORPHEUS     2001-present  

Research on any variability in pore water chemistry of Boom Clay

NF-PRO EC   2004-2007  

- Study of the effect of oxidation on Boom Clay
- First borehole drilling using nitrogen
- In-situ pH measurement and in-situ pore water sampling

OPHELIE     1992-2002  

Surface testing of emplacement of radioactive waste in a disposal gallery

ORPHEUS     2000  

Study of the geochemistry (Eh and pH) of Boom Clay pore water

PEGASUS     2004  

Study of the evolution of the partial pressure of dissolved gas

PHEBUS EC   1991-1995  

Study of the desiccation of clay induced by the ventilation in HADES

PRACLAY     2007-present  

- Gallery & Crossing tests: construction of a gallery perpendicular to the main gallery
- Seal test: hydraulic sealing of the PRACLAY gallery
- Heater test: large-scale heating experiment to study the combined effect of heat and excavation on clay with the aim of confirming and refining existing knowledge on the subject

PRETEL     1994-2004   Design and testing of a system for installing the gallery lining in micro-tunnels in poorly indurated clay
RADWASTOM3 EC   1986-1989  

In-situ characterisation of Boom Clay behaviour

RESEAL I, II EC   1997-2007  

Sealing of a borehole and shaft in poorly indurated clay

SELFRAC EC   2001-2004  

Research on the self-sealing capacity of Boom Clay

TIMODAZ EC   2006-2010  

Effect of increased temperature on the excavation-damaged zone around the galleries

TRANCOM EC   1996-2004  

Study of the migration behaviour of organic material in clay