Effect of Low-Enriched Uranium Targets Irradiation on Major Fission Elements and Uranium Speciation

The speciation of uranium and effect of major fission products after low-enriched uranium targets being irradiated and solvated were analyzed using the geochemical program CHEMSPEC. The results indicate that the speciation of uranium in water is determined by pH value and the concentration of uranyl, and polynuclear complexes may be generated at high concentration of uranyl. Nitrate anion in the solution may interact with uranyl, and at high concentration of nitrate, uranyl exists as UO22+ and UO2NO3+. The presence of CO2 at low concentrations of uranium brings substantial distribution uranyl carbonate, while this is negligible at high concentration of uranyl due to heavy hydrolysis and aggregation of uranyl. The calculations also show that the major fission products, Tc, I, and Mo, do not affect the speciation of uranium when their concentrations are below 0.01 mol center dot L(-1)w and when they exist as TcO4-, I-, MoO42-.