There is a need to categorize and structure knowledge related to nuclear accidents. Development of the structure is challenging unless conducted with consideration of the experience of people who were involved in the accidents. In order to support those activities, the IAEA has taken a leading role to assist in the development of a knowledge organization system and associated taxonomy for nuclear accident knowledge domain, which could be implemented and applied by Member States’ nuclear organizations. This publication is intended to support Member State activity in managing knowledge from serious nuclear accidents, providing a description of knowledge organization system features, information about the developed system taxonomy, and details on the methodology to organize knowledge in this area.