Nuclear energy is the energy contained within the nucleus of an atom. It can be released from the atom through a process called nuclear fission, which involves the splitting of atoms. This process releases a large amount of energy in the form of heat and radiation. In nuclear power plants, this energy is used to boil water and produce steam, which then turns turbines to generate electricity.
Hybrid nuclear energy is a proposed means of generating energy through a combination of nuclear fusion and fission processes. The first nuclear power plant was built in the 1950s, and global installed nuclear capacity grew to 100 GW in the late 1970s, and then grew rapidly during the 1980s, reaching 300 GW in 1990. On June 27, 1954, the Obninsk nuclear power plant in the USSR became the first nuclear power plant in the world to generate electricity for a power grid, producing about 5 megawatts of electrical energy. Nuclear power plants use low-enriched uranium fuel to produce electricity through a process called fission, the splitting of uranium atoms in a nuclear reactor.
The chain reaction produced by nuclear fission is monitored in nuclear power plant reactors to produce a desired amount of heat. This reaction is controlled by inserting control rods into the reactor core, which absorb neutrons and slow down the reaction. The steam pressure turns a generator, which produces electricity. Despite the military nature of the first nuclear devices, the 1940s and 1950s were characterized by strong optimism about the potential of nuclear energy to provide cheap and infinite energy.
Nuclear fusion is another process by which atoms can be combined or fused to form a larger atom. This process releases even more energy than fission but has yet to be harnessed for commercial use. Nuclear proliferation is the spread of nuclear weapons, fissile material and weapon-related nuclear technology to states that do not yet possess nuclear weapons. Many technologies and materials associated with the creation of a nuclear energy program have a dual-use capability, since they can also be used to manufacture nuclear weapons.
The severity of nuclear accidents is generally classified using the International Nuclear Event Scale (INES) introduced by the International Atomic Energy Agency (IAEA). The most important waste stream from nuclear power reactors is spent nuclear fuel, which is considered high-level waste. On the other hand, energy reactors can also reduce nuclear weapons arsenals when military-grade nuclear materials are reprocessed for use as fuel in nuclear power plants.