Recommended equation for corrosion rate of austenitic stainless steels in liquid sodium at elevated temperature

For the design of the liquid metal fast breeder reactor, the corrosion behaviors of austenitic stainless steels SUS 304, 316 and 321 were investigated in high temperature flowing sodium. Such factors as sodium exposure time, downstream factor, sodium temperature and oxygen content in sodium are considered as main factors of sodium environment which influence the corrosion behavior of structural materials. The empirical corrosion equation derived by statistical analysis of available corrosion data is CR=3.08x10⁵·O₂^0.8·exp(-22,000/RT-0.0059(L/D)) where CR: Corrosion rate (μm/yr), O₂: Oxygen content in sodium (ppm) R: Gas constant (1.98 cal/mol·K), T: Sodium temperature (K) L/D: Downstream factor in length/diameter ratio. This equation is applicable to austenitic stainless steels at oxygen content of 1∼10 ppm, temperature of 500∼650℃, downstream factor below 200 and velocities of 2∼4 m/s. (author)