The use of carbohydrazide for plutonium concentration stripping in separator with inert packing

For the purpose of removing plutonium from uranium- plutonium extract it is proposed to employ concentration stripping process with the use of separator and a new reducing reagent: Carbohydrazide CO(N{sub 2}H{sub 3}){sub 2}. Using plutonium stripping from solution simulating the composition of extract of spent nuclear fuel from VVER-1000 reactor (without γ-emitting isotopes), with O: A ratio of = 28, a product solution was obtained containing 17.8 g/l of plutonium, 29.2 g/l of uranium and more than 1 g/l of technetium. The experiment on real spent fuel from VVER-1000 with burn-up of more than 50 GW*d/t of uranium after 17 year exposure, performed in the shielded box of FSUE 'MCP', confirmed the effectiveness and feasibility of the proposed process. Through concentration stripping (O:A = 20), a plutonium product solution was obtained with a part of uranium with the following composition: [U] = 150 g/l; [Pu] = 23,5 g/l; [Np] = 1,7 g/l, [Tc] = 1.5 g/l; gamma exposure rate - 0,022 mR/s*l. Direct extraction of plutonium in this operation was 95.3%, the rest of plutonium is refluxing to the preceding stage of the extraction cycle. A process flow diagram with organization of plutonium recycling is proposed, allowing for its completemore » removal into a single stream. Carbohydrazide is an effective reducing agent of plutonium (IV), ensuring the stability of uranium-plutonium separation process. (authors)« less