Abstract

The increasing use of nuclear power highlights the need for safe and effective management of radioactive waste. One type of such waste is spent organic ion exchange resins, which are
widely used for water purification in nuclear power plants. Several treatment methods for spent organic ion exchange resins exist, but no single method has been established as the most optimal.

This thesis aims to identify the Best Available Techniques (BAT) for the treatment of these
resins by applying a weighted multi-criteria analysis (MCA). Four treatment methods are
evaluated. These are immobilization in cement, immobilization in bitumen, immobilization in
polymers and pyrolysis with subsequent immobilization in cement. The multi-criteria analysis is based on criteria such as technological availability, radiation safety, final waste form quality, secondary waste generation, technical performance, non-radiological safety and economic aspects.

The results of the multi-criteria analysis indicate that immobilization in cement can be considered Best Available Techniques for the treatment of ion exchange resins. The results also show that while identification of immobilization in cement as BAT can be considered robust, the analysis is dependent on the scoring framework and weighting assumptions.

Although a multi-criteria analysis enables a structured comparison of the treatment methods,
the results are influenced by methodological choices. Immobilization in cement is favored due to its technological maturity, safety and stable final waste form but is also associated with limitations such as low waste loading. This emphasizes the importance of interpreting the results as indicative rather than absolute, since BAT assessments are context dependent.