Waste and disposal
Radioactive waste: a collective noun
Radioactive waste is like household and industrial waste. It consists of various substances, materials, tools, appliances, pipes, broken equipment, protective clothing... that can no longer be used. So, what is the difference? Radioactive waste contains substances that emit ionising radiation. This radiation penetrates matter, may cause changes and damage living tissues. In other words, it can be harmful to both people and planet. Radioactivity does die out over time. Until the radiation has reached an acceptable level, operators must watch over public health and work out a safe solution.
Categories of radioactive waste
Where does radioactive waste actually come from? The greater part originates from the production of electricity through atomic fission. However, not only nuclear power plants produce radioactive waste. It also comes from nuclear medicine (e.g. injection needles), agriculture (e.g. sterilisation of food through radiation) and industrial activities (e.g. weld inspections). Depending on the intensity of the radiation and its life span, radioactive waste is subdivided into categories: low-, medium- and high-level waste and short- or long-lived waste.
Three solutions for radioactive waste
Every type of radioactive waste requires a specific solution. The Belgian Agency for Radioactive Waste and Enriched Fissile Materials (NIRAS/ONDRAF) is responsible for the short- and long-term management of all radioactive waste. SCK CEN is closely involved in the scientific substantiation of safety files. The key question is: how can we protect people and the environment against the harmful effects of radiation?
Low- and medium-level short-lived waste mainly originates from industrial activities, medicine and scientific research. It can be safely disposed above-ground without risks for the public health of present and future generations. A new surface disposal site is currently being built. Awaiting its completion, the waste barrels are temporarily stored in special buildings.
Highly radioactive and/or long-lived waste mainly originates from fissile material in nuclear power plants and from the dismantling of nuclear installations. International research has shown that geological disposal is the best solution for this type of waste. SCK CEN is a pioneer in the research into the disposal of waste in deep clay layers. Today, it is testing the different options in cooperation with NIRAS/ONDRAF and other Belgian partners.
Geological disposal is necessary but techniques such as separation and transmutation could reduce the footprint of this geological disposal. Transmutation converts radioactive substances with a long life span into less toxic substances with a short life span. With its MYRRHA project, SCK CEN is a frontrunner in the research into this promising technique.
Natural and artificial barriers during geological disposal
During geological disposal, both natural and artificial barriers ensure that the radioactive waste poses no danger to people and the environment for hundreds of thousands of years. Clay is an important natural barrier. It is water-impermeable and retains the radioactive particles so that they can but spread very slowly. Thanks to its plasticity, clay automatically closes all possible cracks and fissures that may arise. As a result, the barrier remains closed. NIRAS and SCK CEN are specifically studying the Boom clay in their underground research laboratory HADES. In addition, highly radioactive waste is packed in specially designed disposal containers: so-called supercontainers. Supercontainers consist of several concrete and steel barriers enclosing the waste.
225 metres below ground level
To test the geological disposal in layers of clay in Boom under real conditions, SCK CEN started in 1980 with the construction of a laboratory at 225 metres below ground level. The underground laboratory was given the apt name HADES, god of the underworld. Here, scientists perform research into the mechanical, chemical and microbiological characteristics of clay and the interaction between radioactive waste and barrier materials. How slowly do the radioactive substances spread in clay? How soon are the packaging materials of the radioactive waste affected? How can we build tunnels and side tunnels? The research results, computer models and simulations are promising. The radioactivity that after thousands of years would be released from the clay layer in strongly diluted concentrations, has no impact on humans or the environment. The underground laboratory HADES is now operated by ESV EURIDICE, an economic partnership between SCK CEN and NIRAS.
Disposal operations beyond HADES
The underground laboratory HADES is an important pillar in the 'Waste and disposal’ research of SCK CEN but there is more. SCK CEN also studies other aspects that could improve waste management and make it safer. The research centre studies a great variety of issues. Which techniques can be used to improve the treatment and conditioning of radioactive waste? How do the different types of material such as clay, glass, concrete and mortar react in the short and very long term? How can we characterise radioactive waste? Which radioactive products can spread in a disposal site? The researchers enter these insights into computer models that are used to support the performance and safety analyses of NIRAS.