This study aims to present the main international, European Union and domestic legal rules on use of atomic energy by applying the method of comparative analysis. Current reason of this topic is the ongoing Paks 2 project. An industrial project like this requires a highly complex and lengthy licensing process and the nuclear power plant units need to comply with several international, European Union and domestic regulations not only during the licensing process, but throughout erection and operation periods as well. Connected with that, this study examines various legal rules on safety application of using atomic energy, underlining the following topics: liability, safety, and nuclear waste management. In Hungary the Hungarian Atomic Energy Authority is liable for adaptation of the relating regulation. It supplies its tasks by cooperating with several international and European Union authorities.