HADES underground laboratory

The HADES URL is the only underground research laboratory in Belgium for experimental research on geological disposal for high-level and/or long-lived radioactive waste. In 1980, SCK•CEN started the construction of this underground laboratory. It was the first underground laboratory in Europe, built in a deep clay formation for the purpose of researching the possibility of geological disposal in clay.

HADES is situated at a depth of 225 meter, in the core of the Boom Clay formation which is present under the terrain of SCK•CEN, between 190 and 290 meter depth. Since 1995, the HADES URL is managed by EIG EURIDICE, the Economic Interest Grouping between SCK•CEN and ONDRAF/NIRAS, the Belgian agency for radioactive waste and enriched fissile materials.

HADES is a research infrastructure and will never be used as a final repository for radioactive waste.

HADES underground laboratory

The Belgian Nuclear Research Centre and HADES

Soon after its foundation, SCK•CEN played a prominent role in the research on safe management and treatment of radioactive waste in Belgium. Since the beginning of the '70s, several experts have been recognizing that the storage of medium- and high-level radioactive waste caused a problem that could mortgage the future of nuclear energy. Furthermore, there was a growing broad international consensus on the fact that geological disposal could be a safe and durable solution for the long-term management of radioactive waste.

In 1974, SCK•CEN initiated the Belgian research programme regarding the geological disposal of radioactive waste. In the initial phase, SCK•CEN made an inventory of the possible host formations for deep disposal of radioactive waste, in close collaboration with the Geological Survey of Belgium. Furthermore, exploratory analyses on rock samples and test drillings were carried out. From the end of the '70s, research was concentrated on deep disposal in clay formations. This led to the construction of the HADES URL on the premises of SCK•CEN.

The construction of HADES

The major phases in the construction of HADES comprised, among other things, the construction of the first access shaft (1980-1982), the building of the first gallery (1982-1983) and the experimental shaft (1983-1984), the extension of the lab with the Test drift (1987), the construction of the second access shaft (1997-1999) and the realization of the Connecting gallery (2001-2002).

Finally, in 2007, the PRACLAY gallery was constructed perpendicular to the Connecting gallery. This gallery will be used for the large-scale PRACLAY Heater experiment to study the impact of heat, emitted by high-level radioactive waste, on the Boom Clay properties.

Construction history of HADES

The role of the HADES URL in the Belgian research programme on geological disposal

The research programme on the geological disposal of radioactive waste in Belgium is coordinated by ONDRAF/NIRAS. The focus of the RD&D is to assess and demonstrate the safety and feasibility of a geological repository in poorly indurated clay. SCK•CEN is the main research partner in this domain. ONDRAF/NIRAS and SCK•CEN are the constituent members of the EIG EURIDCE, responsible for the management of HADES. 

HADES plays a key role in the research for several reasons

Technical feasibility

First of all, the construction of the underground research laboratory made it possible to develop industrial technologies for constructing, operating and sealing off a waste repository in deep, poorly indurated clay formations like the Boom Clay. With the construction of HADES, the technical feasibility of constructing a geological disposal infrastructure was demonstrated. Moreover, the excavation techniques have continuously been improved and methods have been developed to minimise the hydro-mechanical disturbance of the clay formation.

On-site experiments 

Furthermore, numerous on-site experiments are carried out in HADES to assess the safety of a geological repository in poorly indurated clay. In HADES scientists can conduct experiments in realistic "repository" conditions in the deep clay formation to study for example the behaviour of different waste forms, the anaerobic corrosion of steel containers, the geochemical processes in the Boom Clay, the chemical behaviour of the radionuclides once released from the waste, the migration of radionuclides and gases in Boom Clay and the chemical, thermo-hydro-mechanical perturbations of the Boom Clay host rock. HADES is a licensed nuclear research facility. This offers scientists the unique opportunity to use a wide range of radioactive tracers and sources for their experiments.

All this experimental work has led to a better insight into the processes that determine the long-term behaviour of radioactive waste in real disposal conditions. For example, migration data coming from experiments in HADES are incorporated in geochemical and/or transport models and in safety calculations. The latter allow to analyse the long-term evolution of the disposal system. The fact that the experiments can be conducted over a long period of time (decades) makes it possible to check and refine these models and calculations. Results of this research indicate that geological disposal in a clay formation that has been stable for millions of years and that possesses good sorption properties, can be considered as a safe and durable solution.

Large scale demonstration tests

Large scale demonstration tests are performed in HADES to confirm the safety and feasibility in realistic "repository" conditions. The PRACLAY experiment is a good example of such a demonstration test. In this experiment, the crossing of a side gallery - in this case the PRACLAY gallery - to a main gallery was demonstrated, the sealing of galleries was tested by using bentonite clay, and the impact of heat on the thermo-hydro-mechanical behavior of the clay formation is studied on a large-scale.

30 years of expertise

The use of a wide range of instruments and monitoring techniques in the clay for more than thirty years now, resulted in an expertise in this domain that can help to develop a monitoring strategy for a future repository.


Finally, HADES plays an important role for communicating with everybody who is involved or interested in the research on geological disposal. A visit to HADES contributes to showing the variety of experiments and to give visitors a clear idea on how a real repository could look like. 

HADES in an international context

HADES still is one of the reference laboratories for research on geological disposal of radioactive waste in clay formations. The expertise developed in HADES on geological disposal in clay is recognised all over the world.

Since the '80s, SCK•CEN and EIG EURIDICE participated in numerous international research programmes that are financed by the European Commission within the Framework Programmes. EIG EURIDICE for example was coordinator of the TIMODAZ-project (2006-2010) en participated recently in the MoDeRn-project (2009-2013) on monitoring. The URL HADES is internationally recognized as a "Center of excellence in training and demonstration in underground research facilities". This network is supported by the International Atomic Energy Agency (IAEA) in Vienna.

Furthermore, in order to maintain the internationally recognized lead of SCK•CEN regarding research on geological disposal in clay and to put it at the disposal of the international community, SCK•CEN strives for a durable integration of its research activities in a broader context. To this end, SCK•CEN, EIG EURIDICE and ONDRAF/NIRAS develop structural collaboration forms on large research infrastructures like HADES with other countries that consider also geological disposal of the nuclear waste  in clay.

Contact: Jan Rypens