Plans to introduce nuclear energy into the national energy mix in Poland assume the construction of nuclear facilities from scratch. The government plan assumes the installation of 6 to 9 GWe in large nuclear power plants based on pressurized water nuclear reactor technology. Polish industry, in turn, expresses interest in small modular nuclear reactors. The third option that is analyzed as part of the DEsire project is nuclear retrofit, i.e. replacing existing conventional energy sources with nuclear sources. The aim of the project is to develop a plan for decarbonization of the national economy based on nuclear technologies. The use of nuclear reactors of generations III, III+ and IV is considered. In the first phase of the project, an inventory of existing power plants and combined heat and power plants in Poland was carried out. Over 120 power units were analyzed and the suitability of these units for nuclear retrofit was assessed. Based on the defined technical and safety criteria, ranking lists were developed, divided into readiness for retrofit using generation III/III+ and IV nuclear reactors. As part of this work, selected aspects related to the safety of nuclear facilities were analyzed. This analysis concerns the top three positions from each of the previously mentioned ranking lists. In each case, a nuclear system was proposed and its technical safety aspects were assessed, as well as legal safety aspects related to the specific location of the facility. The technical part of the analysis was based mainly on technical data provided by nuclear reactor manufacturers, and where possible, available operational data was also used. In the second part of the analysis, attention was paid to the legal restrictions related to locating a nuclear facility in a given location, including the possibility of such a solution and the size of exclusion zone and low population zone. Another element of the analysis is the aspect related to the security of continuity of energy supplies. The obtained results indicate that the nuclear retrofit option may be a reasonable solution in many cases.