Nuclear power is the use of nuclear reactions that release nuclear energy to generate heat, which most frequently is then used in steam turbines to produce electricity in a nuclear power plant. As a nuclear technology, nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions.
Presently, the vast majority of electricity from nuclear power is produced by nuclear fission of uranium and plutonium.
Nuclear decay processes are used in niche applications such as radioisotope thermoelectric generators.
Generating electricity from fusion power remains at the focus of an international research phase of development.
This article mostly deals with nuclear fission power for electricity generation.
As total life-cycle greenhouse gas emissions per unit energy generated of fossil fuels are ten to a hundred times more than low carbon power generation, expansion of both nuclear and renewables is required to meet increasing electricity and hydrogen needs whilst limiting global warming. Since its commercialization in the 1970s, nuclear power has prevented about 1.84 million air pollution-related deaths and the emission of about 64 billion tonnes of carbon dioxide equivalent that would have otherwise resulted from the burning of fossil fuels in thermal power stations. As of 2018, there are 58 power reactors under construction and 154 reactors planned, with a combined capacity of 63 GW and 157 GW, respectively. As of January 2019, 337 more reactors were proposed.
Most reactors under construction are generation III reactors in Asia.Civilian nuclear power supplied 2,488 terawatt hours (TWh) of electricity in 2017, equivalent to about 10% of global electricity generation.
As of April 2018, there are 449 civilian fission reactors in the world, with a combined electrical capacity of 394 gigawatt (GW).
There is a debate about nuclear power.
Proponents, such as the World Nuclear Association and Environmentalists for Nuclear Energy, contend that nuclear power is a safe, sustainable energy source that reduces carbon emissions.
Opponents, such as Greenpeace and NIRS, contend that nuclear power poses many threats to people and the environment.
Accidents in nuclear power plants include the Chernobyl disaster in the Soviet Union in 1986, the Fukushima Daiichi nuclear disaster in Japan in 2011, and the more contained Three Mile Island accident in the United States in 1979.
There have also been some nuclear submarine accidents.
Nuclear reactors have caused the lowest number of fatalities per unit of energy generated when compared to fossil fuels and hydropower.
Coal, petroleum, natural gas and hydroelectricity each have caused a greater number of fatalities per unit of energy, due to air pollution and accidents.Collaboration on research and development towards greater efficiency, safety and recycling of spent fuel in future generation IV reactors presently includes Euratom and the co-operation of more than 10 permanent member countries globally.