The document discusses methodology for managing ageing of nuclear power plant components important to safety. It involves three steps: 1) Screening NPP components to identify those requiring ageing evaluation, 2) Performing ageing management studies on selected components, and 3) Taking ageing management actions based on study results and plant data. The methodology includes a phased approach to ageing management studies, with an initial interim study to review existing knowledge, followed by an in-depth study to address any gaps. Screening of components involves evaluating systems and structures for safety contribution, then evaluating individual components for potential failure impact and susceptibility to ageing degradation.