This Safety Guide provides practical guidance and recommendations on ageing management for the safety related systems, structures and components of research reactors on the basis of current international good practices. It is intended for use by operating organizations in establishing, implementing and improving ageing management programmes for research reactors, and by regulatory bodies in verifying that ageing of research reactors is being effectively managed. The Safety Guide focuses on managing the physical ageing of systems, structures and components important to safety, and also provides guidance on safety aspects of managing obsolescence.