Dissolution of synthetic U-DBP and corrosion of stainless steel by dissolution schemes

In spent fuel reprocessing, UO2(DBP)2 (U-DBP) can be deposited in stainless steel equipment. U-DBP must be removed by dissolution and the process must not cause corrosion to stainless steel. This study was conducted to find the best scheme for dissolution. U-DBP was manufactured by the titrimetric sedi-mentation method. The effects of different factors on the dissolution of U-DBP were investigated. For example, solid-liquid ratio, hydrazine carbonate solutions with different mass components, mixed so-lutions containing different concentrations of H2O2, and different carbonates. The results indicated that U-DBP does not have a regular crystal morphology. With the increase of the solid-liquid ratio and the mass fraction of hydrazine carbonate, the concentration of U(VI) at the dissolution equilibrium increases gradually. The addition of H2O2 has a great promotion effect on the dissolution. However, when the concentration of H2O2 is greater than 0.5 M, the dissolution solution may have an erosive effect on the stainless steel. (NH4)2CO3 can increase the dissolution capacity of dissolved U-DBP, but it may also accelerate the corrosion of stainless steel.(c) 2023 Korean Nuclear Society, Published by Elsevier Korea LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).