Corrosion issues in nuclear fuel reprocessing plants

Corrosion studies of stainless steel 304 L in nitric acid in the presence of uranyl nitrate: effect of temperature and nitric acid concentration

“…This phenomenon is explained that in highly concentrated acid, the Cr 2 O 3 passive layer could not properly stabilize and is dissolved rapidly leading to Cr depletion [10]. The effect of the Cr content is the steel has been described as a keyrole into the corrosion rate value; decreasing Cr content could highly increase the corrosion rate [1]. At that point, the redox potential of the solution will harm the alloy by forcing HNO 3 to oxidizes Cr 3+ into HCrO 4 − (Eq.…”

“…Nuclear fuel reprocessing facilities use a wide range of metallic materials for spent fuel treatment. Under reprocessing conditions, those metallic materials are in contact with highly corrosive nitric acid and the understanding of corrosion of those materials is crucial for the reprocessing facilities stakeholders and represents challenging issues for scientists [1].…”

“…Especially, the Plutonium Uranium Redox Extraction (PUREX) process is widely used in the nuclear industry for uranium and plutonium treatment-recycling of the nuclear spent fuel. The conditions used in the PUREX process, such as temperature (up to 121.9 °C), nitric acid concentration (up to HNO 3 azeotropic level, 15.2 M) varies throughout the different industry engineering designers [1,2]. Generally, two different nitric acid concentrations have been reported in PUREX: 3.5 M, that is one of the most cited concentration for the U/Pu TBP-solvent extraction step [3] and 8 M that is a typical concentration for spent fuel dissolution [4]; the concentration of 8 M is also the limit of use of the austenitic stainless steel 304L (304 L SS) [1].…”

“…Stainless steel 304L is commonly used in vessels in the PUREX system [1,5] and its corrosion behavior in nitric acid has been documented [1,[6][7][8]. Its anodic behavior will remain in the passive corrosion domain and a few nanometers thick passive layer principally composed of Cr 2 O 3 will form on its surface in moderately oxidizing solutions.…”

“…Its anodic behavior will remain in the passive corrosion domain and a few nanometers thick passive layer principally composed of Cr 2 O 3 will form on its surface in moderately oxidizing solutions. Over its limits of use, intergranular corrosion can occur in the transpassive domain, especially in presence of oxidizing species in the solution [1,9,10].…”