Most of the nuclear power plants in the world have been in service for more than 30 years and are likely to pursue a life extension to 60 or even 80 years. The modernization of their equipment, in particular I&C systems, must be achieved in order to preserve and enhance their safety, obtain their operating license according to applicable standards, but also improve their productivity. The modernization or deployment of new I&C systems, in particular for safety classified I&C can be very complex and risky. Therefore many aspects should be considered while building the scope of the modernization, in particular the qualification and licensing, the schedule constraints, the cohabitation between the new systems and the older systems (notably when the new equipment is based on digital technology while the rest is analog) but also organizational requirements. This paper gives an overview of a successful modernization of major parts of the I&C of 2 VVER plants in Loviisa (Finland) including the context, regulatory requirements, stakes, objectives and progress as well as of the technology and technical solutions deployed. It will explain the different phases to consider while conducting such modernization project: - Define the optimum scope to modernize - Consider the site constraints - Monitor project with clear schedule and milestones - Work closely with local safety authorities - Propose the appropriate technologies fitting plants requirements and systems in place From this successful project we will extract the key factors of a successful modernization and how they can be adapted and deployed to other utilities in the world.