Work

Assessment of the Applicability of Alkaline and Carbonate Media in Hydrometallurgical Processing of Spent Uranium-Silicide Dispersion Nuclear Fuel

Year: 2026

Type: conference-paper

Abstract: Using surrogates of uranium-silicide dispersion fuel (U3Si2-Al), the chemical behavior of aluminum, silicon, and uranium in alkaline media was investigated. Dissolution of the aluminum matrix in 2.2 M NaOH containing 1.76 M NaNO3 at 70 °C proceeded quantitatively (>99.9%) within 60 min. In the absence of H2O2, uranium dissolution did not exceed 0.01%, whereas under simulated radiolytic conditions (stepwise addition of 0.01 M H2O2), soluble uranyl peroxo-hydroxide complexes formed, as indicated by absorption bands at 340 and 356 nm, resulting in uranium losses of 15–30%. The apparent activation energy was estimated to be 33.8–47 kJ/mol. Thermal hydrolysis and addition of 0.1 M NaI were proposed to suppress uranium dissolution. Carbonation of aluminate liquors removed 99.0–99.7% of Al and more than 99.5% of Si. Alkali regeneration by causticization closed the alkali recycle loop.

Source: International Conference on Nuclear and Renewable Energy Resources (NURER)

DOI: 10.3390/engproc2026160062