Publisher Summary This chapter discusses nuclear power, nuclear fusion and fission, nuclear reactors, and the related environmental considerations. Nuclear power is the most controversial of all the forms of power generation. Evaluating its significance involves weighing political, strategic, environmental, economic, and emotional factors that attract far more strident partisan views than any other method of electricity generation. A nuclear power station generates electricity by utilizing the energy released when the nuclei of a large atom—such as uranium—split into smaller components, which is a process called nuclear fission. The amount of energy released by this fission process is enormous. There is another source of nuclear energy—nuclear fusion—which involves the reverse of a fission reaction. In this case, small atoms are encouraged to fuse at extraordinarily high temperatures to form larger atoms. Like nuclear fission, fusion releases massive amounts of energy. Radioactive waste disposal has become one of the key environmental battlegrounds over which the future of nuclear power has been fought. Environmentalists argue that no system of waste disposal can ever be absolutely safe. Because some radionucleides will remain a danger for thousands of years, the future is an important consideration.