Surface disposal is only suitable for low-level and/or short-lived waste. The disposal solution for this class of waste must be monitored for a period of 200 to 300 years after which the radioactivity contained in the waste will have abated sufficiently for reuse of the site to be entirely safe.

In 1998, the Belgian government opted for a definitive solution (or a solution liable to become definitive) for the long-term management of low-level and/or short-lived waste. It also decided in favour of disposal and ruled out long-term storage. ONDRAF/NIRAS was therefore commissioned by the government to pursue this line of research and to limit it to existing nuclear sites (Mol-Dessel in Antwerp's Campine region, Fleurus-Farciennes in the province of Hainaut and the two sites on which Belgium's commercially operated nuclear power plants, Doel and Tihange, stand), in addition to areas in which local authorities express an interest. Two technical options are possible for the long-term management of low-level and/or short-lived waste: surface disposal and deep disposal.

	The generic concept of surface disposal
	A variation of the generic concept: a half-buried repository
	The role of local partnerships in the decision-making process

A surface or subsurface repository could be designed to isolate low-level and/or short-lived waste from man and the environment at a location where it is possible to construct facilities that would keep a sufficient integrité for the duration of the 200 to 300-year monitoring period at least.

Shown opposite, the generic concept for surface disposal. Below, the concrete casing in which the drums of conditioned waste are placed in fours.

(1) First of all, the drums of conditioned waste are arranged in fours in a concrete casing (some waste from the dismantling of decommissioned nuclear facilities would be placed directly into the casing). Cement mortar is poured into the casing to fill in the spaces between the drums. The monolithic block obtained in this way facilitates the transportation of the waste to the repository and its recovery if necessary, it also forms the first barrier between the waste and the biosphere.

(2) The second barrier is made up of the concrete modules in which the monolithic blocks are stacked. When the modules are full, they are sealed with a concrete slab.

(3) The third barrier is made up of various layers of covering on top of the concrete modules. The materials used are either natural or man-made. A final layer of vegetation gives the site a natural appearance.

(4) The disposal facility is equipped with monitoring galleries for permanently checking it is in good working order and to be able to intervene if necessary.

A variation of the generic concept: a half-buried repository

Each repository must be adapted for the characteristics of the subsoil in which it is built. On the Mol-Dessel nuclear site, the generic concept of surface disposal (as shown above) is being studied whereas a variation of this generic concept is being studied at the Fleurus-Farciennes nuclear site. It is a repository buried at low depth (see illustration opposite).

During these studies, it became clear that the subsoil of this site was not stable enough to build a surface repository. However, solid and sufficiently stable rock which the foundations of a repository could be built on was located at a depth of 20-30 meters.

The principle of multiple safety function also applies in this facility. The waste is isolated from man and the environment inside monolithic blocks (the concrete casings in which the drums of conditioned waste are arranged in fours and over which mortar is poured (1)). These monolithic blocks are stacked by a travelling crane in a cylindrical silo (2) (instead of concrete modules) surrounded by a water tight wall (3). During the operation, the repository is covered to protect it from bad weather. When the silo is full, it is closed off by a concrete slab and a covering composed of various water tight layers. These layers are made up of natural and man-made materials. A half-buried repository can also be monitored (4) for permanently checking it is in good working order and to be able to intervene if necessary.

ONDRAF/NIRAS studies are not restricted to technical matters. Indeed, a long-term radioactive waste management solution must not only be safe and technically feasible, it must also be socially acceptable. ONDRAF/NIRAS was quick to realize that if a planned repository is to become reality, dialogue with the local communities is essential. This is why the citizen has been given a central place in its research. An open, collaborative structure was devised to allow local people to take part in the studies, namely, the partnership. These partnerships take the form of local structures that, with technical and scientific support provided by ONDRAF/NIRAS, are responsible for preparing and presenting preliminary projects for surface and deep disposal as part of an overall project. The overall project must provide added value to the municipalities involved and must command a broad consensus. The aim is to ensure that the long-term management of low-level and/or short-lived waste benefits any region hosting a repository in economic, social and cultural terms.

Four municipalities have expressed their willingness to take part in the ONDRAF/NIRAS work programme: Fleurus, Farciennes, Mol and Dessel, and three local partnerships have been created (STOLA in Dessel in 1999, MONA in Mol in 2000 and PaLoFF in Fleurus-Farciennes in 2003). With the creation of these partnerships, ONDRAF/NIRAS has opted for a progressive, reversible and democratic decision-making process. It is the community who will decide if a (surface or deep) repository for low-level and/or short-lived waste will be built in Belgium, where it will be built and on what terms. The constitution of a local partnership, however, is by no means a commitment. At all times, the municipalities and the populations concerned retain sovereignty over the decision to pursue the studies or not. Furthermore, the fact that a partnership exists in no way means that a repository for low-level and/or short-lived waste will actually become reality on the territory of the participating municipalities. After ratification by the councils of the municipalities concerned, the local partnership dossiers will be presented to the federal authorities.

For further information:
See our list of publications in French or Dutch (heading: "Long-term management of low-level and short-lived waste")

If you don't understand a term, please refer to our glossary.