Oxidation behavior of stainless steel for fast breeder reactor fuel cladding.

Abstract Oxidation behavior of the stainless steel for a fast breeder reactor fuel cladding was studied in the temperature range of 873–1,073 K. The oxygen pressure in the fuel-cladding gap was simulated by the Mo/MoO2 or the NbO2/Nb2O5 oxygen buffer. The oxidation kinetics was found to obey the parabolic rate law. The temperature dependence of the parabolic rate constants is given by the following equations: Under the oxygen pressure controlled by the NbO2/Nb2O5 oxygen buffer (Po 2 = l-6×10−25 Pa) Under the oxygen pressure controlled by the Mo/MoO2 oxygen buffer (Po 2 = l.9×10−21 Pa), kp(T) =4.75×10−7 exp (-99.6×103/RT) where kp and the activation energy are expressed in terms of kg2/m4·s and J/mol, respectively. The oxidation mechanism was discussed on the basis of the metallographical information and the value of activation energy of the parabolic rate constant. KEYWORDS: SUS-316 stainless steelfuel-cladding chemical interactioninner corrosionhigh temperatureoxidationoxygen potentialparabolic rate constantoxygen pressureFBR-type reactorstemperature dependence