The Composition of NO_x Generated in the Dissolution of Uranium Dioxide

Dissolution of uranium dioxide in nitric acid media: what do we know?

“…They have confirmed the presence of NO and NO 2 , but N 2 O is not detected in this study. Sakurai et al [9] have analyzed the off-gases after trapping in a liquid-nitrogen trap. The presence of NO and NO 2 was confirmed, but they do not detect N 2 O in their IR-spectra.…”

“…Given the strong oxidizing property of the nitric acid media in these studies, it is unlikely that N 2 O results of a reaction between the dissolution medium and the off-gases. Thus, the detection by Hermann [5] of N 2 O in the off-gases may find its origin in the difference in the experimental procedures: Herrmann sent the off-gases through a condenser before analyzing it, while Sakurai et al [9] used a liquid-nitrogen trap to recover it before analysis. Glatz et al [8] also placed a condenser between the IR analyser and the dissolution reactor, but the fact that the off-gases are diluted with helium before flowing through it could result in the absence of recombination reactions.…”

“…Many authors have pointed out an evolution of the NO/ NO 2 ratio depending on the concentration in nitric acid of the dissolution solution [5,8,9,12].…”

“…Glatz et al [8] and Sakurai et al [9] have measured the quantity of degased NO x during the dissolution of UO 2 pellets under various nitric acid concentrations. Table 2 presents the results they obtained, and It must also be pointed out that in the studies of Glatz et al [8], two types of pellets were dissolved.…”

“…The second hypothesis introduces an equilibrium between nitric acid and NO x species: Sakurai et al [9] claim that the only dissolution reaction taking place is represented by equation (1), and that the observed NO and NO 2 mixture results of the equilibrium existing between these two species in nitric acid solutions.…”