Logistic Study for the Belgian Repository Concept

The Belgian waste management organisation, ONDRAF/NIRAS, plans to carry out waste conditioning and interim storage of the resulting waste packages on the site of the future Belgian geological disposal facility (GDF). It is assumed that the waste packages will have to harden for 28 days in a buffer before they are ready to be transported and emplaced underground. After emplacement of a specific number of waste packages inside a disposal gallery, the remaining voids will be backfilled.

To optimise duration and costs of the disposal project, the operational concept must be suitable to achieve an emplacement rate that is not significantly lower than the predefined waste package production rate. In order to evaluate the overall system behaviour, BGE TECHNOLOGY GmbH carried out a study on the transport and emplacement processes as well as on the backfilling of the disposal galleries. As part of this study, a computer model was developed that simulates the work steps during the operation of the GDF. This allowed investigating the effects of varying parameters on the emplacement rate and identifying measures to increase the operating performance.

According to the ONDRAF/NIRAS concept for intermediate level waste, only waste packages of one out of eight waste families will be disposed of in each disposal gallery. Five of these families are assigned to only a single disposal gallery, which precludes that transport and emplacement operations are carried out in parallel to backfilling operations. This means that the emplacement rate is lower than for the waste streams where parallel emplacement and backfilling of drift sections is possible. For the normal operating scenario, the emplacement rates are slightly higher than the production rates for waste families with several emplacement drifts and slightly lower if only one drift is available. In the latter case, the buffer is consequently being filled with waste packages, and – if the maximum capacity is reached – the conditioning facility comes to a standstill. If more than one disposal gallery is available for emplacement, the buffer stock is being reduced and eventually emplacement operation even has to wait for waste packages to harden. This evolution is visualised in the figure above, which shows the total number of waste packages inside the buffer during the entire emplacement phase. The black curve represents the total number of containers in the buffer and the coloured ones indicate the number of cured containers for the different waste streams.