Assessing Corrosion of UNS S30403 Stainless Steel for Applications in Nuclear Waste Reprocessing Systems

Abstract

To investigate the corrosion of centrifugal contactors in the spent nuclear fuel treatment process called UREX+, corrosion of UNS S30403 stainless steel has been studied in three acidic aqueous solutions of 5.0 M nitric acid (HNO3), 5.0 M HNO3 + 0.1 M hydrofluroric acid (HF), and 5.0 M HNO3 + 0.1 M HF + 0.1 M Zr4+. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were conducted at temperatures of 25, 40, and 80°C and different hydrodynamic conditions (0, 1,000, 2,000 rpm). The results showed that the mixture of HNO3 and HF was the most corrosive environment. Addition of Zr4+ ions to this acidic solution reduced the corrosion caused by HF to levels similar to those found in HNO3 solutions. Higher corrosion rates were obtained as the solution's temperature increased while hydrodynamic conditions had a less significant effect on corrosion rates.