Resorcinarenes and aza-crowns as new extractants for the separation of technetium-99

Among the radionuclides considered for separation within the UREX + concept is Technetium-99, a uranium fission product with a low energy beta emission and a half life of 2.13 x I years. The fission products, present in the high level waste (HLW) issued from the PUREX process, are mainly responsible for the long term radiotoxicity of this HLW stream. Partitioning and transmutation as a means of reducing the burden on a geological repository requires Tc-99 to be removed from the HLW (partitioning) and then fragmented by fission (transmutation), which allows reduction of the radiotoxicity inventory of the remaining waste. As an example, a single isotopic species (Tc-99) can be transmuted by single neutron capture into the stable noble metal ruthenium (Ru-100). Selective extraction of Tc-99 needs to be investigated. We describe herein the synthesis of new macro-compounds which can be flinctionalized with oxygen, sulfur, and nitrogen donating functional groups with various cavity sizes andlor bonding modes, and the assessment of their extraction properties towards Tc-99.