Dissolution of contaminant Zr-DBP and corrosion of stainless steel by dissolved solution

Abstract

In the nuclear spent fuel reprocessing, zirconium dibutyl phosphate (Zr-DBP) is deposited on the surface of stainless steel equipment, making spent fuel reprocessing difficult. Therefore, in this study, hydrazine carbonate ((N2H5)2CO3) was used to dissolve Zr-DBP. The effects of solid–liquid ratio, different mass fractions of (N2H5)2CO3 solutions, and (N2H5)2CO3 solutions containing different concentrations of hydrogen peroxide (H2O2) on the dissolution of Zr-DBP were investigated. The corrosion rates of different dissolution solutions on stainless steel were also investigated. When the mass fraction of (N2H5)2CO3 in solution was increased from 1 % to 20 %, the concentration of Zr(IV) at dissolution equilibrium increased from 1.05 g/L to 1.61 g/L, respectively. When the dissolution temperature was kept in the range of 25 °C to 65 °C, the increasing temperature promoted the dissolution of Zr-DBP. The presence of H2O2 induced the production of the white precipitates zirconium hydroxide (Zr(OH)4). In addition, the corrosion rate of stainless steel gradually increased from 0.00153 mm/a to 0.0138 mm/a when the concentration of H2O2 in the (N2H5)2CO3 solution was increased from 0 M to 1.5 M. The dissolution ability of Zr-DBP in different carbonate solutions was (N2H5)2CO3 ≥ ammonium carbonate ((NH4)2CO3) > sodium carbonate (Na2CO3) ≥ potassium carbonate (K2CO3).