Innovative partitioning of high activity nuclear wastes A successful EC-funded project focused on the development of a more simplified process for the selective extraction of the potentially toxic minor actinides from high active liquid waste. Climate Change and Environment © Thinkstock One of the key objectives of radioactive waste management programmes is the reduction of their long-term activity before disposal. Within this context, minor actinides coming from the reprocessing of nuclear spent fuels constitute potentially high toxic wastes. For this reason, they are selectively removed from solutions through partitioning techniques and they are further destroyed using transmutation methods, whereby long-lived isotopes are turned into short-lived isotopes. Current strategy involves a three-step separation process for the elements, such as americium and curium included in highly active concentrates. Taking advantage of earlier research on the advanced selectivity capabilities of specialised substances, the CALIXPART project focused on functionalised calixerenes for developing a one-step removal of these two elements. Thereby, newly synthesised functionalised CMPO-calixarenes were extensively studied and their quantum chemistry molecular modelling was provided. Furthermore, various types of tests were conducted, such as stability tests towards nitric media concentration, hydrolysis and radiolysis. Other analyses performed included complexation studies for three different families of compounds, such as calixarenes, cavitands and cyclotriveratrylene, as well as extraction studies for approximately one hundred compounds. The promising results display the increased potentialities of calixarenes for their further use as an effective and safe separation technique in future partitioning methods. Image shows: Tris-CMPO-acetamide-calix[4]arene, functionalised on the wide-rim, proposed for trivalent actinide separation Keywords Partitioning, high activity, nuclear waste, minor actinides, americium, curium, calixarenes
