This Safety Guide supplements and provides recommendations on meeting the requirements related to ageing management and long term operation that are established in IAEA Safety Standards Series No. SSR-2/1 (Rev.1), Safety of Nuclear Power Plants: Design, and IAEA Safety Standards Series No. SSR-2/2 (Rev.1), Safety of Nuclear Power Plants: Commissioning and Operation. It provides guidance for operating organizations on implementing and improving ageing management, obsolescence management and on developing a programme for safe long term operation for nuclear power plants. It may also be used by the regulatory body in preparing regulatory requirements, codes and standards, and in verifying effective ageing management, obsolescence management and preparation for safe long term operation of nuclear power plants.