Monday, June 18, 2007 - 9:35 AM
The Peregrins (Boise Centre on the Grove)

Phase Transfer Kinetics of Trivalent Actinides and Lanthanides in Phosphorus Reagent Extraction Systems

Mikael Nilsson, Washington State University, Pullman, WA and Ken Nash, Washington State University, Pullman, WA.

With a steady increase in energy demand and the consensus to reduce greenhouse gases, nuclear power production has regained interest as a good source of power. Plans to close the nuclear fuel cycle to reduce waste volumes and storage times will require chemical treatment of the spent nuclear fuel. One of the necessary steps for successful operation of a closed fuel cycle is the separation of trivalent actinides from lanthanides, both present in the spent nuclear fuel. Because the chemical behavior of these elements are so similar their mutual separation is a challenging task. Over the years of research on this subject several chemicals and extraction systems have been identified that will yield a separation factor suitable for industrial applications. Even though processes have been found, there are still many unknown parameters that need to be investigated, to support their deployment at industrial scale. The work presented here focuses on the TALSPEAK process, a system based on a phosphoric acid extracting agent in combination with an aqueous hold back reagent. The phase transfer kinetics in a 2-phase system have been investigated using a non-stirred extraction cell. The presence of a carboxylic acid, such as lactic acid, has been reported to improve kinetics and so it was investigated whether this would have an effect in a diffusion controlled environment. The transfer of the lactic acid itself between the two phases have also been investigated. This information would be valuable for process purposes as well as basic chemical understanding.