γ-Ray radiolysis of acetohydroxamic acid in HNO 3 and its radiolytic product

Abstract

Acetohydroxamic acid (AHA) is a novel salt-free reagent used for the separation of Pu and Np from U in the advanced Purex process. This paper reports the γ-ray damage of AHA in HNO₃ and its radiolytic product. For 0.2 mol L⁻¹ AHA in 0.2–2.0 mol L⁻¹ HNO₃ irradiated at a dose of 5–25 kGy, the radiolytic rate of AHA is 6.63–77.5%, and it increases with the HNO₃ concentration and absorbed dose. The main radiolytic gases are N₂O and H₂, with volume fractions of (0.500–16.2) × 10⁻² and (1.30–11.8) × 10⁻³, respectively, and they increase with the absorbed dose; the H₂ volume fraction decreases with increasing HNO₃ concentration. The main liquid radiolytic products are CH₃COOH and HNO₂, and their concentrations are (3.40–19.7) × 10⁻² and (0.200–4.80) × 10⁻³ mol L⁻¹, respectively, which increase with the HNO₃ concentration. Since a significant concentration of HNO₂ is present in the irradiated AHA-HNO₃ solution, a holding reductant must be used to destroy HNO₂ and stabilize Pu(III) and Np(V) when AHA is applied for the separation of Pu and Np from U.