Reactor Analysis Team is one of the research teams created within Świerk Computing Centre project. Our main task is to perform safety analyses for modern nuclear reactors using advanced computational methods. The demand for that type of team appeared after release of the plans to build first nuclear power plant in Poland. Long time before lunching first power unit it is necessary to perform many simulations that will estimate its safety. Some procedures for plant operators must be determined and validated as well. That can only be accomplished by using mentioned computational methods, that allow simulation a reactor steady state operation as well design and beyond design-basis accidents (transients), which in turn allows us to determine strengths and weaknesses of its safety features and systems.