Radioactive Waste

Radioactive waste is the collective name for all material containing radioactive elements for which no practical applications are known. It originates from e.g. the medical sector, the industry or electricity production.


Radioactive waste is classified into 3 categories: A, B or C. The classification is mainly based on the type and intensity of the ionizing radiation.

  • Cat. A: low- and intermediate-level short-lived waste (working clothes, gloves, safety shoes, masks, laboratory waste, etc.)
  • Cat. B: low- and intermediate-level long-lived waste (residual products from the processing of fuel, filters from the primary cooling circuit, etc.)
  • Cat. C: high-level waste (irradiated fuel)

Who keeps track of radioactive waste?

In Belgium, NIRAS-ONDRAF (National Institution for Radioactive Waste and Enriched Fissile Materials) and its subsidiary Belgoprocess manage radioactive waste from nuclear power plants, industrial and medical applications and research centres. They aim to isolate the waste from the environment until its radioactivity is reduced to a sufficiently low level by natural decay. 

Almost all radioactive waste generated in Belgium is stored at the NIRAS-ONDRAF and Belgoprocess facilities in Dessel. The spent nuclear fuel from the Belgian nuclear power plants in Doel and Tihange is an exception to this rule. Pending future political decisions on its processing or final storage, it is temporarily stored in containers in designated buildings on the sites of the nuclear power stations.

Why can’t the amount of high-level waste be reduced?

During the production process, the uranium-235 contained in the fuel elements is split. An enormous amount of heat is released during this process. After 3 to 4 years in the reactor core, an element is depleted, which means that all usable energy has disappeared from it. These depleted fuel elements are cooled under water and subsequently moved to a storage building which is located on the sites of the nuclear power plants. A political decision on the final, controlled storage is still pending.

How to reduce the amount of medium and low-active waste?

Electrabel has its own facilities for waste treatment, which process low- and intermediate-level liquid and solid waste. Water filters, low-level resins and sludge are mixed with concrete in special waste drums. This method of immobilisation of waste is also called ‘conditioning’. The drums are stored temporarily on the sites of the nuclear power plants before being transferred to Belgoprocess (subsidiary of NIRAS).

This method of immobilisation of waste is also referred to as 'conditioning'. The drums are temporarily stored at the sites of the nuclear power plants before being transferred to Belgoprocess (subsidiary of ONDRAF/NIRAS).

The solid compactable waste is compressed and transported to Belgoprocess for further processing. Shredding is another option. The waste is then incinerated in a specially equipped incinerator at Belgoprocess. Low-level liquid waste is treated and re-used if possible, discharged after treatment or conditioned for further processing by evaporation. Reducing the amount of low- and intermediate-level radioactive waste, including through prevention and recycling, is a permanent objective.

How much radioactive waste is produced?

The total volume of nuclear waste, including radiation-protective packaging, that all producers generate and foresee for the future is 160,000m³, or 43 Olympic-sized swimming pools. The share of highly radioactive waste is only 1.75%. (Source: ONDRAF/NIRAS Annual Report 2021, situation on 31/12/2021, Cat A volume conditioned in monoliths, Cat B & C volumes incl. primary packaging.)

How is radioactive waste definitively stored?

Short-lived waste accounts for 90 % of the total volume of radioactive waste. This waste consists of overshoes and clothing, cleaning materials such as rags and mops, residues from reactor water treatment, filters, resins, etc. The radioactivity of this waste decreases over time, and falls by 50 % every 30 years. For this short-lived waste, surface storage is provided. The drums for temporary storage are encapsulated in a concrete container, which in turn is sealed in an underground concrete layer.

Long-lived high-level radioactive waste consist mainly of spent fuel elements. This waste emits a lot of heat and has to be contained for tens of thousands of years until its radioactivity has fallen back to the level of natural background radiation. This type of waste represents only 1 % of the total volume of radioactive waste in Belgium. The disposal of this type of waste has been studied for many years, weighing up various options against each other. Since 1973, the Belgian Nuclear Research Centre (SCK-CEN) has been carrying out extensive research into the Boom clay layer under its sites, which are eligible for 'deep geologic disposal'. They investigate whether this is safe and feasible and use a special instrument for this purpose: an underground lab excavated in that clay at a depth of some 225 metres. This method of disposal is also the solution recommended internationally by the International Atomic Energy Agency, an autonomous organization of the United Nations. In Belgium, however, the final political decision has yet to be taken. In the meantime, Electrabel is storing the spent fuel in containers and facilities specially designed for this purpose at the Doel and Tihange sites, in complete safety.

What happens when the nuclear power plants are ever dismantled?

98% of all material resulting from the dismantling of the nuclear power plants is non-radioactive, or conventional, waste that will be recycled to the maximum extent possible. 

Radioactive material is treated and decontaminated as much as possible, according to strict standards, thus minimizing the amount of radioactivity. The remaining 2% therefore consists mainly of Category A waste that will be transferred to ONDRAF/NIRAS. They will condition this waste at the Belgoprocess site and package it into large blocks of concrete (monoliths). The monoliths will then be placed in surface disposal. High-radiation internal components of the reactor will be transported, as Category B waste, in specially designed containers to the temporary on-site storage locations in anticipation of the final deep disposal of NIRAS-ONDRAF.