3rd-INCC

Deep purification of uranium extract from technetium

19 Sept 2011, 17:30

1h 30m

Paladini (Città del Mare, Terrasini - Palermo - Sicily - Italy)

poster Nuclear Fuel Cycle Poster Section 1

Speaker

Mr Vitaly Vidanov (Open Joint Stock Company “Academician A.A. Bochvar High-Tech Research Institute of Inorganic Materials”)

Description

Uranium purification from technetium in the process of spent nuclear fuel reprocessing is one of the most complex problems. Uranium reclaim for separating plant is to be extremely decontaminated from Tc because of the problems at the sublimation stage caused by volatile TcF6 formation during uranium recycling process. There is a conflict between Thorp plant requirements for uranium product after the second extraction cycle (Tc content 4 mg/kg U) and ASTM С787-03 standard, which requires Tc content in uranium hexafluoride less than 0.5 mg/kg U and in some cases the level of uranium decontamination from Tc in this product should be less than 1.6 mkg/kg U. This conflict could be resolved by uranium reclaim additional radiochemical reprocessing for supplying purified product to the sublimation plant. It is evident that such technology makes reprocessing process rather expensive. The aim of the research work was to find and work out such a process, that can provide effective and not expensive deep uranium purification from Tc on the basis of extraction spent fuel reprocessing technology. The solution of mentioned problem is an extraction-chromatographic purification of uranium extract by usage of aqueous reducing agents solution as a purifying stream. These agents reduce Tc(VII) to nonextractable Tc(IV). The process of purifying is carried out in cyclically-countercurrent feed mode of purified and purifying streams in a column filled with porous excipient (charged with aqueous purifying stream). It is shown that depending on composition of the aqueous phase concentration factor varies from 40 and above. These conditions provide practically complete treatment of uranium extract.