The HADES underground research laboratory provides an ideal opportunity to work under realistic conditions, acquiring the expertise necessary to develop a safe waste repository. In this sense, the activities in HADES make a significant contribution to the RD&D programme of ONDRAF/NIRAS.
Over the past 30 years the underground research laboratory is where industrial technologies have been developed for building, operating and closing a waste repository in deep clay. The extension of HADES between 1997 and 2007 demonstrated that it is possible to construct such a disposal infrastructure using industrial techniques. You can find out more about the development of excavation techniques here.
When the repository is eventually built and starts operating, state-of-the-art technologies will probably be available that did not exist when HADES was under construction. If necessary, these new technologies can be pre-tested in the HADES underground research laboratory before being implemented in the real repository.
Scientists conduct experiments in HADES under realistic conditions to obtain detailed data about the characteristics and behaviour of clay at great depth. In conjunction with above-ground tests, these in-situ experiments provide the necessary input to be able to assess the safety of geological disposal in clay in the long term. For instance, HADES research on the chemical characteristics of the water in clay and the migration of radioactive substances has made it possible to model the retarded dispersion of these radioactive substances in the clay under realistic conditions.
HADES is a nuclear research facility (class II) and is licensed by the Belgian Federal Agency for Nuclear Control (FANC). This means that scientists have access to a wide range of radioactive tracers and sources to ascertain the behaviour of radioactive substances in clay. Some of these experiments began more than 25 years ago and are still being monitored. This makes HADES unique in the world. The long timescale makes it possible to compare the predictive calculations against the actual changes that occur over time and fine-tune the models if necessary. This ultimately provides further confirmation of the safety of the disposal system.
In some cases it is important to run a full-scale simulation of the combined effects that will occur during the operation of a geological disposal facility. The large-scale PRACLAY experiment, which will run for 10 years, is designed to simulate the heat that will be generated when high-level waste is placed in a repository after having been cooled on the surface for several decades. The experiment enables the temperature profile to be studied in conjunction with the mechanical disturbance due to excavation of the gallery, on a full scale, i.e. as if it were a real repository. The purpose of the 10-year heater experiment is to confirm and refine existing knowledge about the behaviour of clay when it is subjected to heat, with a view to demonstrating the technical feasibility of the disposal concept for heat-producing waste.
HADES makes it possible to test new instruments and measurement techniques in clay, and hence explore the possibilities and limitations of monitoring. Thirty years’ experience in using measuring instruments in the Boom Clay is invaluable when it comes to developing the monitoring strategy for a future waste repository. EIG EURIDICE can bring this expertise to projects at European level (such as the MoDeRn project), which provide a framework for the development and possible implementation of geological disposal monitoring activities. The cAt project for surface disposal of low- and medium-level short-lived waste also benefits from our expertise in instrumentation and monitoring.
HADES also plays an important part in communicating with anyone who is involved in research on geological disposal or who wants to find out more about it. Visitors to HADES gain an appreciation of the scale and quality of the research conducted and come away with a more concrete idea of what a geological repository might actually look like. Even once construction work starts, HADES will continue to fulfil a major communication role, since visits to an operational repository will not always be possible for the public.
HADES is an invaluable tool for managing the knowledge and expertise that has been gained over the past 30 years, and for passing it on to the next generation of technicians, scientists and engineers who will be involved in building the waste repository. In the longer term, even once the repository is operational, HADES can serve a useful purpose in maintaining public involvement, thus ensuring that knowledge is transmitted from one generation to the next.