Nuclear engineering is the branch of engineering concerned with the application of breaking down atomic nuclei (fission) or of combining atomic nuclei (fusion), 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 reactors, power plants, or weaponry. 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 (e.g., radioactive waste disposal) and the problems of nuclear proliferation. This field also includes chemical engineering and electrical engineering. Professional areas The United States currently generates about 20% of its electricity from nuclear power plants. Nuclear engineers in this field generally work, directly or indirectly, in the nuclear power industry or for national laboratories. Current research in the industry is directed at producing economical and proliferation-resistant reactor designs with passive safety features. Some government (national) labs provide research in the same areas as private industry and in other areas such as nuclear fuels and nuclear fuel cycles, advanced reactor designs, and nuclear weapon design and maintenance. A principal pipeline/source of trained personnel (both military and civilian) for US reactor facilities is the US Navy Nuclear Power Program, including its Nuclear Power School in South Carolina. Employment in nuclear engineering is predicted to grow about nine percent in the year 2022 as needed to replace retiring nuclear engineers, provide maintenance and updating of safety systems in power plants, and to advance the applications of nuclear medicine. Nuclear medicine and medical physics Medical physics is an important field of nuclear medicine; its sub-fields include nuclear medicine, radiation therapy, health physics, and diagnostic imaging. Highly specialized and intricately operating equipment, including x-ray machines, MRI and PET scanners and many other devices provide most of modern medicine's diagnostic capability—along with disclosing subtle treatment options. Nuclear materials Nuclear materials research focuses on two main subject areas, nuclear fuels and irradiation-induced modification of nuclear materials. Improvement of nuclear fuels is crucial for obtaining increased efficiency from nuclear reactors. Irradiation effects studies have many purposes, including studying structural changes to reactor components and studying nano-modification of metals using ion-beams or particle accelerators. Radiation protection and measurement Radiation measurement is fundamental to the science and practice of radiation protection, sometimes known as radiological protection, which is the protection of people