After the events in Fukushima (March 2011) the U.S. congress directed the Department of Energy (DOE) to focus efforts on the development of fuels with enhanced accident tolerance. These materials may be able to tolerate loss of active cooling in the core for a considerably longer time period while maintaining or improving the fuel performance during normal operation conditions. Advanced alloys such as ferritic steels are being investigated both under normal operation conditions in high temperature water (e.g. 288°C) and under accident conditions for reaction with steam up to 1200°C. Ferritic steels are highly more resistant to stress corrosion cracking in high temperature water than austenitic materials of similar composition. Ferritic steels such as T91 and HT9 are also less susceptible to irradiation damage such as void swelling.