How does nuclear fission generate electricity?

Otto Hahn at the Kaiser Wilhelm Institute reported the experimental discovery of nuclear fission and Lise Meitner at the University of Stockholm with Otto Frisch provided the physical explanation for why a heavy nucleus splits. Enrico Fermi at the University of Chicago led the first controlled chain reaction, demonstrating how the process could be sustained and managed. Those foundational advances explain both the cause of fission and the basic route by which it is converted into usable energy.

How fission produces heat
In a nuclear fuel isotope such as uranium-235 or plutonium-239 a free neutron can be captured by the nucleus, making it unstable and causing it to split into two smaller fragments. The split releases the binding energy that had held the nucleus together. Most of that energy appears as kinetic energy of the fission fragments and prompt neutrons; collisions between these energetic fragments and surrounding atoms heat the fuel and its cladding. Additional energy appears as gamma radiation and delayed beta decay of fission products, which also deposit heat. The prompt neutrons can induce further fissions, creating a chain reaction that must be controlled to produce steady heat rather than an explosive release.

From heat to electricity
In a nuclear power plant the reactor core holds fuel assemblies immersed in a coolant that removes the heat produced by fission. Moderators such as light water or graphite slow neutrons to energies where fission is more likely, and control rods containing neutron-absorbing materials adjust the reaction rate. The removed thermal energy is used to produce steam that spins a turbine coupled to an electrical generator. Thermodynamic limits, turbine design and heat sink availability determine the plant’s thermal efficiency, while auxiliary systems and safety layers are governed by national regulators and international guidance from the International Atomic Energy Agency.

Relevance, consequences and human dimensions
Nuclear fission offers a very high energy density compared with chemical fuels, which makes it attractive for baseload electricity with low operational carbon emissions. At the same time, fission creates long-lived radioactive waste and requires secure handling to avoid environmental contamination and proliferation risks. Accidents, though rare, can have profound health, cultural and territorial consequences as seen in historical events that led some nations to alter policy. National choices vary: France emphasizes centralized nuclear generation through its state utility EDF, while Germany moved to phase out reactors following public and political reactions to the Fukushima accident.

Environmental and social consequences also reach back to fuel supply. Uranium mining has affected local and Indigenous communities, creating health and land-use concerns that require remediation and consultation. Cooling water discharges and thermal plumes can affect aquatic ecosystems near plants, necessitating site-specific environmental assessments. Technical practice, regulatory oversight and transparent stakeholder engagement together determine whether fission-generated electricity is deployed with acceptable risks and benefits for communities, ecosystems and territories.