The project of Refurbishment Zakučac HPP is the largest and the most important project inside the Elecro Energetic Sector of the Republic Croatia. Word is about very complex and the high risk energetic project. One of the most risky activities turbine inlet sphericale valve refurbishment . High risk weights are just activities in the machine hall of Zakucaca HPP. Of course, it's about raising and lowering the shutter in his cave. After the secesfull finishing iniciation and phase of the project planing the phase of implementation of the life cycle of project has been planned by the four steps during four years (2012 – 2016.). The basicly, each step includes replacement of the one production unit (turbine with main inlet sphericale valve and governing system, generator, high voltage conection, block transformers, high voltage cables). Project has achieved its goals: - design, installation and commissioning of the new production units, - the maximum increasing water discharge (from 220 m3/s to 240 m3/s) throug the existing hydraulic waterway infrastructure and, - the maximum increasing of the output power of the power plant (from 486 MW to 538 MW) and production of the additional electrical energy, - automation and optimisation of the power plants production process, - improving the safety and reliability of the power plant, - increasing eficiency of new production units by the implementation new modern equipment at the last one technolocigal level, - unification of the production equipment, due to lower investments and maintenances costs and simplier maintenance, - improving environmental protection free of the expensive civil works and touching of the environment (getting new energy on existing facilities instead of building new ones), - the phase of project implementation free of the stopping of the comercial explatation of Zakucac HPP (during replacment of one production unit another 3 production unit products electrical energy). After the successful closing the Project of the Refurbishment Zakocac HPP, it is the full evident that Zakocac HPP reaches additional importance inside the Croatian electro energetic system expecially because of the exploatation during paek load and secundary regulation.