Nuclear fuel cycle facilities (NFCFs) have played a major role in the development and application of nuclear technologies in various fields, including nuclear power and nuclear science and technologies for over seven decades. Approximately 70% of the operating NFCFs in the world are more than 30 years old, thus it is important that life management programmes are established and implemented. This publication provides practical information on factors affecting ageing and their consequences, and mitigating action required for nuclear fuel cycle facilities in the operational stage including modernization and refurbishing. It also provides the considerations for long term operation of a nuclear fuel cycle facility. The information in this publication will be useful to the operating organizations, regulatory bodies and other organizations involved in the design, construction, operation and management of nuclear fuel cycle facilities’ safety.