Stress Corrosion Cracking Behavior of Austenitic Stainless Steel SS304 for Dry Storage Canisters in Simulated Sea-Water

A number of recent studies have suggested that dry storage canisters (DSCs) made of austenitic stainless steel SS304 to store spent nuclear fuel located along coastal region may undergo stress corrosion cracking (SCC) if their useful life is extended due to lack of a permanent underground burial repository. It, therefore, becomes necessary to understand SCC behavior of SS304 in marine environment. We report here our results on SCC of SS304H in simulated sea-water using fracture mechanics approach as a function of temperature. The average crack growth rates were noted to be 0.975 × 10⁻¹⁰ ± 9.528 × 10⁻¹², 3.258 × 10⁻¹⁰ ± 9.551 × 10⁻¹¹, and 1.580 × 10⁻⁹ ± 2.593 × 10⁻¹⁰ m/s at 22, 37, and 60 °C, respectively. The activation energy of the crack growth process was estimated to be 60.9 kJ/mol corresponding to diffusion of hydrogen in steel. Optical microscopy revealed intergranular nature of the crack growth.