Conditioning of radioactive waste
From problematic stream to a stable, safe form
For the nuclear sector, waste conditioning is more than a mandatory process: it is a crucial step for safety, regulatory compliance and sustainable final disposal. SCK CEN supports organisations at every stage, from research and formulation development to large-scale testing and the effective conditioning of small quantities of complex waste streams.
Our approach
Your challenge, our priority. Powered by our science, infrastructure and expertise.
Each waste stream is different: chemical, physical, radiological. The greatest challenges arise from problematic streams, such as highly acidic solutions, reactive salts, organic waste, Cs-Sr-containing residues and SMR waste.
This drives operators of nuclear installations, processors, waste management organisations and research centres to search for clear and reliable answers to fundamental questions:
- Which matrix is compatible with my waste stream?
- Will the waste form remain stable in the long term?
- Does this strategy meet the waste acceptance criteria (WAC)?
- How scalable, feasible and safe is this process in practice?
SCK CEN provides that clarity.
We combine advanced modelling, laboratory experiments, full-scale simulations and, where necessary, the actual conditioning process itself, so you can rely on safe, validated and future-proof solutions.
The advantages of SCK CEN
A unique combination of expertise and infrastructure:
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Extensive knowledge of conditioning techniques
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Extensive experience in developing and testing formulations for the conditioning of diverse radioactive waste types in various matrices.
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Experts in addressing known challenges such as alkali-silica reactions and delayed ettringite formation (ASR-DEF).
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Integrated experimental and modelling expertise to predict the long-term performance of a waste form.
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Fully equipped for microstructural, mineralogical and (radio)chemical characterisation of waste forms
Our services
From concept to conditioned finished product
SCK CEN supports operators and industrial partners throughout the entire radioactive waste management process: from the initial assessment of a waste stream and the development of an appropriate conditioning strategy to its validation and practical implementation. You can rely on SCK CEN for the full process or for specific parts of it, depending on your needs.
1. Analysis & advice
Each project begins by gaining insight. We conduct a thorough analysis of the waste stream: its chemical composition, radiological properties, potential interactions with binders and the relevant waste acceptance criteria for final disposal. This enables our experts to assess and compare the feasibility of various conditioning strategies. Our experts deliver scientifically substantiated advice on the optimal matrix or immobilisation technique for your waste stream, including risk evaluation and improvement options.
2. Formulation development
Once the approach is defined, we develop the optimal formulation. We combine geochemical modelling, literature reviews and statistically designed, experimentally supported test programmes to determine which binders are most compatible with the waste. Depending on the chemistry of the waste stream, we investigate conventional cement mixes, composite binders, alkali-activated materials or geopolymer systems. This stage produces a selection of candidate formulations offering strong stability, compatibility and conformity with the waste acceptance criteria.
3. Laboratory tests (hot and cold)
In our laboratories, we test how the formulations behave in real conditions.
In our cold laboratories, we study workability, rheology, microstructure, mineralogy and mechanical strength, as well as resistance to degradation mechanisms such as leaching, alkali silica reaction (ASR) and delayed ettringite formation (DEF). Advanced climate chambers and analytical techniques enable accurate testing and in-depth evaluation.
In our hot laboratory, we test the optimised formulations with real radioactive materials. This is crucial for assessing chemical compatibility, radiolytic stability and immobilisation efficiency. This allows us to accurately assess how the waste form behaves under realistic conditions.
Case: From complex waste to stable plasma slags
Historical LILW, often encapsulated in cement or bitumen, can be difficult to characterise and may not meet disposal requirements. Learn how plasma treatment converts this waste into homogeneous, stable plasma slag for long-term safety.
4. Full-scale validation
If the laboratory results are positive, we carry out full-scale testing in our cold full-scale mixing facility for waste containers. We monitor the mixing behaviour, the energy required, heat development during hydration, curing rate and volume stability. These large-scale tests are essential to ensure that the conditioning route is not only theoretically sound and feasible at small scale, but also operationally viable and suitable for industrial application.
5. Effective conditioning
New and complex waste streams increasingly require tailor-made solutions. Therefore, SCK CEN develops solutions for the conditioning of small volumes of complex or atypical radioactive waste streams.
Our approach does not start from a single predefined technology, but from the specific characteristics of the waste. We assess each waste stream on a case-by-case basis, evaluate different conditioning routes where necessary, and determine the most suitable solution based on objective technical, safety and operational criteria. We can then prepare the selected formulation, carry out the conditioning process, and deliver a safely packaged end product that complies with the applicable waste acceptance criteria.
Thanks to our unique combination of research infrastructure, pilot facilities and operational expertise, we provide independent advice, tailor-made solutions and practical support. This enables customers to benefit from an integrated service without having to invest in specialized infrastructure or develop additional in-house expertise.
Additional conditioning options for specific or emerging waste streams are currently being developed. Contact our experts to discuss the possibilities for your particular waste stream.
Our infrastructure
Unique in Belgium. Indispensable for your project.
With infrastructure that is unique in both Belgium and Europe, we offer everything needed to develop, test and validate conditioning routes at full scale. From initial calculations to the conditioned final product: every step remains within one integrated environment, fully traceable and under controlled conditions.
Our facilities include:
- Cold cement laboratories
- Hot cement laboratory with glove boxes and fume cupboards
- Advanced climate chambers
- Microstructural and mineralogical analytical techniques
- Radiological characterisation techniques
- Geochemical and thermal modelling platforms
- Facilities for full-scale mixing and testing in waste drums
This combination enables both fundamental research and commercial projects to be carried out safely, accurately and with full traceability.
ANUBIS & the Recovery Plan for Belgium and Europe
Several facilities that are essential to SCK CEN’s expertise and research in radioactive waste conditioning have been made possible through funding from the European Union. In 2021, SCK CEN received EU funding for the ANUBIS project, a strategic initiative aimed at strengthening research and innovation infrastructure in Belgium and across Europe. This investment forms part of the broader recovery efforts to foster scientific excellence, technological innovation, and sustainable economic growth.
For more information, please visit the ANUBIS project webpage.