Investigations to Determine the Extent of Degradation of TBP/Oderless Kerosene Solvent in the New Separation Plant, Windscale

Abstract

An experimental program to study solvent degradation in the New Separation Plant at Windscale is reported. To determine solvent life, TBP/ odorless kerosene was recycled through an extraction, stripping, and solvent process system having similar residence times to those proposed for the design. Radiation was provided in a single stage by a strontium-90 source. The experiment was used to predict the effects of solvent degradation, as measured by Zr/Nb distribution, on the first cycle of purification and solvent washing. Examination ot this degraded solvent from the recycle experiment by infrared analysis showed the presence of C=O, and NO/sub 3/ groupings, but no other groups were identified. Batches of solvent were degraded in a high gamma field at doses up to 125 watt-hr/liter in contact with nitric acid and uranyl nitrate, and were found to give high Zr/Nb retention in a standard Z/sup 2/ test, while the retention of Ru was found to be small with irradiations up to 35 watt-hr/ liter; at 60 watt-hr/liter significant retention of the Ru was noted. The G-values for production of compounds containing carbonyl, carboxylic acid, nitrate, and nitrogroupings were determined in this series of irradiations. Synthetic long chain (C/sub 12/) ketones, carboxylic acids, nitromore » compounds, nitrites, nitrates, olefines, hydroxamic acids, nitro alcohols, and short chain (C/sub 4/) nitiolic acids were examined as possible ligands. Of these, only the hydroxamic acids give powerful retention of activity, and the zirconium complexes were sufficiently stable to withstand the extraction and washing conditions. Comparison of the batch degraded trials and the recycle trials showed that the pattern of products detectable by infrared analysis differed. The removal of ligands by the normal alkali washes used in the New Separation Plant was compared with that obtained with alkanolamines, alkaline permanganate, and fluoride solutions, and with purification by distillation techniques. (auth)« less