3Designs for nuclear power plants increasingly include passive features. A major focus of the design of modern fast reactors is on inherent and passive safety. Inherent and passive safety features are especially important when active systems such as emergency shutdown systems for reactor shutdown are not functioning properly. This publication discusses the past experience in the development of such systems along with the research that is ongoing. It is a comprehensive publication which provides information on the basic design principles for passive shutdown systems and the related operational experience gathered so far, and also reviews the innovative concepts under development and the needs for research and development and qualification tests.