Extensive knowledge and acceptability of pertinent properties, wide fabrication experience, and code acceptance have led to selection of 2¼ Cr— 1 Mo steel for the Clinch River Breeder Reactor Plant steam generators. Limitations of this alloy indicate that further development of high-strength ferritic steels containing 9 to 12% chromium and the high-nickel Alloy 800 could lead to superior materials, and programs to develop these materials have started. Combustion Engineering has surveyed the experience with the high-strength ferritic steels and prepared ingots of 26 selected compositions. Charpy V-notch tests and metallography have been used to characterize these alloys, and optimum welding rod compositions for these alloys are under development. Westinghouse-Tampa is undertaking a program to gain code acceptance of Alloy 800. A program has been set up to provide the information required for design and fabrication of reliable components. Progress has been made on characterization, the role of tertiary creep in failure, and the development of welding processes. The Heppenstall Company is demonstrating its process for manufacturing large high-quality ingots.