At this point, no political decision has been taken in Belgium regarding what to do in the long term with the spent fuel elements. Consequently, the final disposal facility cannot yet be made available by the National Institution for Radioactive Waste and Enriched Fissile Materials (NIRAS) over the coming decades. The fuel elements should therefore be stored on site in safe fuel casks.
At the moment Doel and Tihange nuclear power plants have already facilities where spent fuel elements are stored safely. The current storage facility is increasingly coming closer to the limit. Once the existing storage facilities are full, it will no longer be possible to store new spent fuel elements. If this is the case, then after the final shutdown of the nuclear power plants it will not be possible to start with the dismantling. So additional safe temporary storage facilities are required.
What happens to spent fuel elements?
After 3 to 4 years in the reactor core the energy in a fuel element is depleted and it is permanently removed from the reactor core. These spent fuel elements still contain a lot of heat and emit radiation. To cool down, they are placed in a water basin in a reinforced building at the nuclear power plant for a period of 5 to 10 years.
Wet and dry storage
In the Tihange nuclear power plant the elements will be moved, after cooling down for a few years, to another specially designed building where they are also stored under water. So called “wet storage”.
In Doel, the so-called “dry storage” was already selected in the past. After first cooling in the water basin, the elements are moved under water to strong, specially designed casks, which are then stored in a building: the so-called fuel container building. The building has already been safely in use since 1995.
Electrabel has positive experiences with both types of storage (dry storage in Doel and wet storage in Tihange). International experience exchange indicates that both storage options meet the necessary nuclear safety requirements. In other countries both types of storage are also used, depending on the local needs and requirements.
After carrying out various analysis projects regarding the additional storage capacity, Electrabel decided to build a dry storage facility. This type of storage is more flexible. In dry storage facilities the spent fuel is stored in dual-purpose containers. The containers have a permit for both (intermediate) storage as well as for transport (inside and outside the power plant) as part of later final storage of the spent fuel elements.
Nuclear safety top priority
Nuclear safety is the number one priority for Electrabel! To guarantee this, there are a number of barriers which protect the spent fuel against external events.
The most important protection is the container in which the spent fuel elements are stored. This provides protection against internal and external risks such as moisture, corrosion, fire, explosions, earthquakes and even the impact of an aircraft crash. The containment of the radioactive material is also guaranteed under all conditions. In addition to the container, the building also provides an additional barrier and radiological protection. Among other things, the building is also resistant to extreme natural phenomena such as earthquakes.
At Tihange nuclear power plant the construction started in 2020 with the aim of taking the new storage building into service in 2023. At Doel nuclear power plant, construction started in 2021, with the objective of taking the new buildings into service in 2025.
The buildings are designed for a storage period of 80 years. This was discussed with and approved by the Federal Agency for Nuclear Control (FANC). How long the containers will remain there depends on the decision which the Belgian government still needs to make regarding the final storage concept for this waste in Belgium and the effective construction and commissioning of this final storage by NIRAS.
Based on current findings, we assume that after a period of 80 years a different location will be available for the final storage of the spent fuel elements.
The new interim storage facility has been named SF² (Spent Fuel Storage Facility) and looks similar to the existing building at Doel Nuclear Power Plant.
The new buildings in Doel and Tihange consist of a handling hall and storage area. The storage area is 90 meters long, 36 meters wide and 23 meters high. The design includes 108 positions, equalling 18 rows, each with 6 spaces. 11 spaces remain free to enable containers to be repositioned under all circumstances. Therefore 97 containers will be able to be placed in the new building.
The containers have a diameter of around 2.5 meters, are up to 6 meters high and weigh around 100 tonnes empty. Up to 24 fuel elements can be stored in one container or cask.
The spent fuel still remains warm for a considerable period. The new building will have - just as with the current building at Doel NPP - a design which uses passive ventilation, i.e. without fans, to extract this heat. This means cooling is ensured at all times.
Not only is the building resistant to exceptional natural phenomena such as earthquakes, also the expected rise in the sea level has been taken into account.
A building is inherently unnecessary to protect the containers. The casks are designed to be fully capable of protecting the spent fuel elements. In many nuclear power plants, for example in the United States, the containers are stored outside, but in Belgium we have opted for an even more robust safety concept.
Quantities of spent fuel
90% of all the radioactive waste in Belgium is low-radioactive waste. This relates to waste with a short lifespan such as gloves, work clothing, masks, etc. Only 1% of the total radioactive waste is high-level radioactive and relates to the spent fuel from nuclear power plants in Doel and Tihange. This high-level radioactive waste contains 95% of the total radioactivity of the Belgian radioactive waste.
The annual quantities of spent fuel material produced in the Doel and Tihange nuclear power plants equates to around 20 tons per reactor per year. For all nuclear power plants this means 5 grams per inhabitant in Belgium per year or the equivalent of a thimble.
The waste produced is one of the by-products of generating electricity by nuclear energy. This waste consists of products which are safely handled in a controlled manner from a technical perspective and are suitable for long-term storage.