Comparison in the aggregation behavior of long chain monoamide extractants and TBP during loading of U(VI) from simulated U-Zr solution

Metallic fuels are the most promising candidates for use in fast breeder reactors owing to their passive inherent safety features, ergonomic fabrication methods and viability for achieving high burn-up values. Reprocessing of UPuZr alloy fuels by aqueous route would require extractants which selectively extracts uranium and plutonium with minimal co-extraction of zirconium present in the spent fuel solutions. Long chain monoamide extractants shall be better extractants for reprocessing of metallic fuel solutions as they have reported to show negligible extraction of zirconium in comparison to the conventional extractant, n-tributylphosphate (TBP). In the present study, dynamic light scattering (DLS) spectroscopy is employed for comparing the aggregation behaviour of different long chain monoamides including N,N-di-hexyloctanamide (DHOA), N,N-di-hexyldecanamide (DHDA), N,N-di-decyloctanamide (DDOA), N,N-di-hexyl-2-ethylhexanamide (DH₂EHA), N,N-di-2-ethylhexyloctanamide (D2EHOA) with TBP during the extraction of U(VI) from a simulated dissolver solution of un-irradiated U-Zr fuel. The study of aggregate sizes in extractant systems provides valuable information regarding the third phase formation tendency of extractants under different conditions. The extraction of nitric acid and U(VI) by different extractants are shown