Flow accelerated corrosion (FAC) is divided into two processes; one is the corrosion (chemical) process and the other is the flow dynamics (physical) process. The corrosion process is the essential process to cause FAC and the flow dynamic process is the accelerating process to enhance FAC occurrence.

Average flow velocity and temperature in each elemental volume along the flow path are calculated with 1D computational flow dynamics (CFD) codes first, corrosive conditions, e.g., oxygen concentration and electrochemical corrosion potential, along the flow path are calculated with a hydrazine oxygen reaction code, precise flow pattern and mass transfer coefficients at the structural surface are evaluated with 3D CFD codes, and then danger zones are pointed out by analyzing the major FAC parameters obtained above. At any danger zone, wall thinning rates are estimated with combined codes of static electrochemical analysis and dynamic double oxide layer analysis. The effects of candidates for countermeasures, e.g., O2 injection, increasing pH and replacing materials, on FAC mitigation could be evaluated. Future trend of wall thinning could be also predicted by the model.

           Shunsuke Uchida (B.S., Physics, Osaka University, PhD, Nuclear Engineering, University of Tokyo) has been a senior adviser at Nuclear Power Engineering Corporation (NUPEC) and a research consultant at Japan Atomic Energy Agency after he retired from Tohoku University in 2005. His latest concerns are on the effects of hydrogen peroxide on corrosion of stainless steel in high temperature pure water. He is currently serving as the chair of the Water Chemistry Division of the Atomic Energy Society of Japan (AESJ).