Estimating the corrosion rate of stainless steel R-SUS304ULC in nitric acid media under concentrating operation

The amount of corrosion of the austenitic stainless steel was evaluated considering the changes in solution composition and boiling during actual concentration operations. Austenitic stainless steel R-SUS304ULC is the structural material of the highly radioactive liquid waste concentrator in Japanese spent fuel reprocessing plant, which treats highly corrosive nitric acid solutions during enrichment operations. The study results show that it is necessary to focus on nitric acid concentrations, oxidizing metal ion concentrations, and decompression boiling as factors that accelerate the corrosion rate of stainless steel because of cathodic reaction activation.