Nuclear engineering is the branch of engineering concerned with the application of breaking down atomic nuclei or of combining atomic nuclei or with the application of other sub-atomic processes based on the principles of nuclear physics. In the sub-field of nuclear fission it particularly includes the design, interaction and maintenance of systems and components like nuclear reactors, nuclear power plants or nuclear weapons. The field also includes the study of medical and other applications of radiation particularly Ionizing radiation, nuclear safety, heat/thermodynamics transport, nuclear fuel or other related technology and the problems of nuclear proliferation.