[en] Demonstrating that ageing and performance are being effectively managed is a key element of life management programmes. This requires the establishment of maintenance aimed at identification, monitoring and control of the ageing processes that affect power plants. This has led to the need to assess maintenance practices and adapt them to the basic objective of life management which is conservation, mitigation and/or monitoring of ageing processes that affects plant safety and profitability. The benefit-to-cost results are maximized when there is early identification of the areas requiring ageing control. New regulatory requirements, regarding monitoring ageing processes and ensuring efficient maintenance as a safety guarantee, have reinforced the need for maintenance evaluation to optimise resources and tools. The following is a summary of the methodologies and contents of NPP maintenance evaluation programmes and the experience gained in their application to Spanish NPPs. (Author)