Nuclear power is the second-largest source of low-carbon electricity today, supplying 10.5% of global electricity

Nuclear power is generated by a controlled chain reaction inside a nuclear reactor, most commonly in a process called nuclear fission. In fission, neutrons collide with uranium or plutonium atoms, causing the atoms to split and release additional neutrons and energy in the form of heat. This heat is used to convert water into steam, which drives turbines to produce electricity. A nuclear reactor was first used to produce electricity in the 1950s, in light of discoveries made through research efforts previously focused on developing nuclear weaponry. A series of commercial reactors for electricity production have since been developed. Today, nuclear power is gaining importance driven by the climate change agenda since it emits minimal greenhouse gases, at levels similar to renewable energy in terms of total life cycle emissions per unit of energy generated. Nuclear power projects are heavily dependent on government policy due to their capital-intensive nature, and are strictly regulated as they deal with radioactive materials.  

Nuclear power is controversial in some locations due to these radioactive materials and the potential health hazards they pose. A number of destructive accidents have occurred in the history of nuclear power; these include the Chernobyl disaster in the Soviet Union in 1986 and the Fukushima disaster in Japan in 2011. Different nations have widely different visions for the deployment of nuclear power, ranging from France’s 75% dependence on nuclear power for electricity generation to Germany having announced decision to shut down all of its nuclear power plants by 2022. Another important aspect is the disposal of nuclear waste; spent fuel remains active for tens of thousands of years and a proven long-term solution for safely managing and disposing of this radioactive waste is yet to be developed. Although newer, safer and more efficient reactor designs are being constructed today, nuclear power has an uncertain future challenged by public acceptance, costs, fuel resource sustainability and nuclear waste management.

As a potentially safer and less waste-generating type of reaction than fission, nuclear fusion is an ongoing area of research. Several experimental reactors exist, but commercial-scale results remain far from realisation. Small modular reactors are also attracting interest, as they allow for greater flexibility with potential benefits particularly for developing countries with limited grid capacity.