Aqueous Nitric Acid Radiation Effects on Solvent Extraction Process Chemistry

摘要

The use of aqueous nitric acid is ubiquitous in the nuclear industry especially as the diluent for dissolved used fuel in nuclear solvent extraction processes. These acidic solutions are therefore exposed to the radioactive decay energy from the actinides and fission products contained in the fuel. The radiolysis of aqueous nitric acid produces a mixture of radical and molecular species especially the "NO_2 and *NO_3 radicals. We have measured the absorbance of these radicals in pulse-irradiated 6.0 M nitric acid and find that at this acidity no "NO_2 species was detectable. This, coupled with slow rate constants for reaction of "NO_2 with many organic solutes, suggests that "NO_3 radical is the more important reactive species. However, most literature values for 'NO_3 reaction with organic solutes have been made in acetonitrile, rather than aqueous acidic solution, so here we have compared values available in both solvents, including our own measurements, to obtain a quantitative correlation between the two solvents. The implications for the mechanism of the reaction with some ligand solutes are discussed.