DECOMMISSIONING | AUTOMATING CHARACTERISATION & SORTING
70 60 50 40 30 20 10 0
Am-241 U-235 Cs-137 Co-60 Eu-152
0
5
10 Throughput [tons/hour]
15
20
Above left, figure 1: Estimates for achievable detection limits of the system, depending on material throughput, for the most important gamma- emitting nuclides in radiological decommissioning
Above right: The FREMES technology significantly enhances efficiency, reduces costs, and ensures compliance with regulatory standards
The exact values depend on the operational parameters of the sorting process. There are three main
design parameters that influence the system’s design: ● The detection limits and their target values, defined by legal sorting limits
● The maximum material throughput ● The smallest material separation size
Not all of these parameters can be optimised simultaneously without negatively affecting at least one of the others. Therefore, for each specific application, an optimal configuration must be selected.
For the NUKEM design used in Dessel, the following
parameters where applied: ● Detection limit: Below 20 Bq/kg U-235, corresponding to below 0.5 Bq/g U-Total
● Maximum material throughput: 10 –15 tonnes per hour ● Material separation size: Approximately 100 kg
NUKEM provides the optimal design and solution for the customer’s specific application, typically in the form of the
following key project steps: ● General feasibility study on legal requirements and priorities in process parameters
● Detailed study for on-site implementation and waste streams
Additionally, there are several optional enhancements to the system’s capabilities, which can be integrated into the FREMES, if required by the client, such as: Alpha- and Beta counting measurements of the material
surface: These can be used primarily to verify the presence of nuclides detected through gamma activity determination and known nuclide vectors. Since Alpha and Beta radiation are short ranged, the effectiveness of these measurements depends heavily on the specific measurement circumstances. Optical detection methods to detect conventional
contamination or non-mineral components of the material. NUKEM can integrate additional detection systems capable of optically identifying materials such as remaining wall paint, plastic parts, heavy metal contamination, oil or chemical residues. The system can simultaneously characterize and sort the material based on both radioactive content and these additional contaminant factors in a single measurement step.
36 | October 2025 |
www.neimagazine.com
The future of FREMES The FREMES represents a significant advancement in the decommissioning of nuclear facilities. By integrating radiological characterisation and sorting into a single automated process, FREMES addresses the critical need for efficient handling of large quantities of potentially contaminated concrete and building materials. The system‘s ability to continuously and precisely measure and sort bulk materials, such as concrete debris, offers several key
benefits: ● Efficiency and cost reduction: The streamlined process reduces the need for extensive pre- measurements and optimizes the overall decommissioning workflow.
● Flexibility: FREMES is designed to be highly adaptable, allowing customisation to meet specific project requirements, including material preparation, measurement and sorting equipment, and the number of sorting categories.
● Regulatory compliance: The system ensures compliance with legal limits for radioactive materials, providing thorough documentation and facilitating regulatory approval for the release or disposal of materials.
● Reduction of waste disposal costs: By accurately sorting materials into categories such as Free Release, Conditional Release, and Radioactive Waste, FREMES minimises the amount of material classified as radioactive waste, thereby reducing disposal costs.
The successful application of FREMES in several large- scale decommissioning projects, including those involving uranium contamination, demonstrates its effectiveness and reliability. Indeed, earlier this year NUKEM was commissioned by the Swiss nuclear power plant Mühleberg to conduct a feasibility study to assess the use of the FREMES. The feasibility study will provide critical documentation
to support Mühleberg during the qualification of the proposed method by the Swiss Federal Nuclear Safety Inspectorate (ENSI). FREMES offers a robust solution for the decommissioning
of nuclear facilities, combining advanced measurement technology with automated sorting to enhance efficiency, reduce costs, and ensure regulatory compliance. Its inherent flexibility and adaptability make it a valuable tool for addressing the diverse challenges associated with the remediation of concrete and building materials in nuclear installations. ■
Achievable detection limit [Bq/kg]
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