This technical report is intended to support owners of an NPP in the decision-making process and in the preparation for partial or complete modernization of the I&C. For this, it provides: – a summary of the motivating factors for I&C modernization, – the principal options for the elaboration of different scenarios for I&C modernization, – the technical and economic criteria for the selection of a long term I&C strategy, – the principal aspects to be taken into account for a detailed technical feasibility study. In addition, this report contains detailed recommendations and practical advice for: – the technical evaluation of the actual status of the I&C systems, – the content of the I&C system requirement specification and for the project management following the guidance given in IAEA TECDOC 1016 and 1066, – considerations on modernization strategy. Special attention is paid to the improvement of reactor safety and of the human machine interface. The report does not provide I&C design requirements. For these it is assumed that the IAEA Codes and Guides are used as top level documents while IEC publications are mainly used for system design, requirements on equipment and some work methods. IAEA Reports and other documents are referenced to give information that is more detailed on specific areas. The structure of the report is given in Figure 1. The recommended sequence is, first, to summarize the more easily obtained motivations (Clause 5) and then establish a project that works in structured and more and more detailed steps: Long term I&C strategy – Feasibility studies – Tender specification and order (Clause 6). Clauses 7 and 8 may be used as checklists during each step.