Nuclear power

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Nuclear power is the use of

nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by nuclear fission of uranium and plutonium in nuclear power plants. Nuclear decay processes are used in niche applications such as radioisotope thermoelectric generators in some space probes such as Voyager 2. Generating electricity from fusion power
remains the focus of international research.

Most nuclear power plants use

nuclear weapons, reprocessing is seen as a weapon proliferation


437 civilian fission reactors in the world, with overall capacity of 393 GW,[1] 57 under construction and 102 planned, with a combined capacity of 62 GW and 96 GW, respectively. The United States has the largest fleet of nuclear reactors, generating over 800 TWh of zero-emissions electricity per year with an average capacity factor of 92%. Average global capacity factor is 89%.[1] Most new reactors under construction are generation III reactors
in Asia.

Nuclear power generation causes one of the lowest levels of fatalities per unit of energy generated compared to other energy sources.

greenhouse gases. One of the dangers of nuclear power is the potential for accidents like the Fukushima nuclear disaster in Japan
in 2011.

There is a

carbon emissions. The anti-nuclear movement contends that nuclear power poses many threats to people and the environment and is too expensive and slow to deploy when compared to alternative sustainable energy



EBR-1 at Argonne National Laboratory-West, December 20, 1951.[2]

The discovery of nuclear fission occurred in 1938 following over four decades of work on the science of

radioactivity and the elaboration of new nuclear physics that described the components of atoms
. Soon after the discovery of the fission process, it was realized that a fissioning nucleus can induce further nucleus fissions, thus inducing a self-sustaining chain reaction.[3] Once this was experimentally confirmed in 1939, scientists in many countries petitioned their governments for support of nuclear fission research, just on the cusp of World War II, for the development of a nuclear weapon.[4]

In the United States, these research efforts led to the creation of the first man-made nuclear reactor, the

taking place one month later.

The launching ceremony of the USS Nautilus January 1954. In 1958 it would become the first vessel to reach the North Pole.[5]

Despite the military nature of the first nuclear devices, the 1940s and 1950s were characterized by strong optimism for the potential of nuclear power to provide cheap and endless energy.[6] Electricity was generated for the first time by a nuclear reactor on December 20, 1951, at the

In 1953, American President
Dwight Eisenhower gave his "Atoms for Peace" speech at the United Nations, emphasizing the need to develop "peaceful" uses of nuclear power quickly. This was followed by the Atomic Energy Act of 1954
which allowed rapid declassification of U.S. reactor technology and encouraged development by the private sector.

First power generation

The first organization to develop practical nuclear power was the U.S. Navy, with the S1W reactor for the purpose of propelling submarines and aircraft carriers. The first nuclear-powered submarine, USS Nautilus, was put to sea in January 1954.[9][10] The S1W reactor was a pressurized water reactor. This design was chosen because it was simpler, more compact, and easier to operate compared to alternative designs, thus more suitable to be used in submarines. This decision would result in the PWR being the reactor of choice also for power generation, thus having a lasting impact on the civilian electricity market in the years to come.[11]

On June 27, 1954, the

power grid, producing around 5 megawatts of electric power.[12]
The world's first commercial nuclear power station,

Expansion and first opposition

The total global installed nuclear capacity initially rose relatively quickly, rising from less than 1

gigawatt (GW) in 1960 to 100 GW in the late 1970s.[9]
During the 1970s and 1980s rising economic costs (related to extended construction times largely due to regulatory changes and pressure-group litigation)
energy generators economically unattractive.

The 1973 oil crisis had a significant effect on countries, such as France and Japan, which had relied more heavily on oil for electric generation to invest in nuclear power.[15] France would construct 25 nuclear power plants over the next 15 years,[16][17] and as of 2019, 71% of French electricity was generated by nuclear power, the highest percentage by any nation in the world.[18]

Some local opposition to nuclear power emerged in the United States in the early 1960s.

In the early 1970s, there were large protests about a proposed nuclear power plant in Wyhl, Germany. The project was cancelled in 1975. The anti-nuclear success at Wyhl inspired opposition to nuclear power in other parts of Europe and North America.[22][23]

By the mid-1970s

anti-nuclear activism gained a wider appeal and influence, and nuclear power began to become an issue of major public protest.[24][25]
In some countries, the nuclear power conflict "reached an intensity unprecedented in the history of technology controversies".[26][27] The increased public hostility to nuclear power led to a longer license procurement process, regulations and increased requirements for safety equipment, which made new construction much more expensive.[28][29] In the United States, over 120 LWR reactor proposals were ultimately cancelled[30] and the construction of new reactors ground to a halt.[31] The 1979 accident at Three Mile Island with no fatalities, played a major part in the reduction in the number of new plant constructions in many countries.[20]

Chernobyl and renaissance

Pripyat abandoned since 1986, with the Chernobyl plant and the Chernobyl New Safe Confinement
arch in the distance
Olkiluoto 3 under construction in 2009. It was the first EPR
, a modernized PWR design, to start construction.

During the 1980s one new nuclear reactor started up every 17 days on average.[32] By the end of the decade, global installed nuclear capacity reached 300 GW. Since the late 1980s, new capacity additions slowed down significantly, with the installed nuclear capacity reaching 366 GW in 2005.

The 1986

USSR, involving an RBMK reactor, altered the development of nuclear power and led to a greater focus on meeting international safety and regulatory standards.[33]
It is considered the worst nuclear disaster in history both in total casualties, with 56 direct deaths, and financially, with the cleanup and the cost estimated at 18 billion 
Rbls (US$68 billion in 2019, adjusted for inflation).[34][35] The international organization to promote safety awareness and the professional development of operators in nuclear facilities, the World Association of Nuclear Operators
(WANO), was created as a direct outcome of the 1986 Chernobyl accident. The Chernobyl disaster played a major part in the reduction in the number of new plant constructions in the following years.[20] Influenced by these events, Italy voted against nuclear power in a 1987 referendum, becoming the first country to completely phase out nuclear power in 1990.

In the early 2000s, nuclear energy was expecting a

carbon dioxide emissions.[36]
During this period, newer generation III reactors, such as the EPR began construction.

  • Net electrical generation by source and growth from 1980. In terms of energy generated between 1980 and 2010, the contribution from fission grew the fastest.


    electrical generation
    by source and growth from 1980. In terms of energy generated between 1980 and 2010, the contribution from fission grew the fastest.

  • Electricity production in France, showing the shift to nuclear power.   thermofossil   hydroelectric   nuclear   Other renewables
    Electricity production in France, showing the shift to nuclear power.
      Other renewables
  • The rate of new reactor constructions essentially halted in the late 1980s. Increased capacity factor in existing reactors was primarily responsible for the continuing increase in electrical energy produced during this period.

    The rate of new reactor constructions essentially halted in the late 1980s. Increased capacity factor in existing reactors was primarily responsible for the continuing increase in electrical energy produced during this period.

  • Electricity generation trends in the top producing countries (Our World in Data)

    Electricity generation trends in the top producing countries (Our World in Data)


Nuclear power generation (TWh) and operational nuclear reactors since 1997[37]

Prospects of a nuclear renaissance were delayed by another nuclear accident.[36][38] The 2011

nuclear safety and nuclear energy policy in many countries.[39]
Germany approved plans to close all its reactors by 2022, and many other countries reviewed their nuclear power programs.[40][41][42][43] Following the disaster, Japan shut down all of its nuclear power reactors, some of them permanently, and in 2015 began a gradual process to restart the remaining 40 reactors, following safety checks and based on revised criteria for operations and public approval.[44]

In 2022, the Japanese government, under the leadership of Prime Minister Fumio Kishida, has declared that 10 more nuclear power plants be reopened since the 2011 disaster.[45] Kishida is also pushing for research and construction of new safer nuclear plants to safeguard Japanese consumers from the fluctuating fossil fuel market and reduce Japan's greenhouse gas emissions.[46] Prime Minister Kishida intends to have Japan become a significant exporter of nuclear energy and technology to developing countries around the world..[46]

Current prospects

By 2015, the IAEA's outlook for nuclear energy had become more promising, recognizing the importance of low-carbon generation for mitigating climate change.[47] As of 2015, the global trend was for new nuclear power stations coming online to be balanced by the number of old plants being retired.[48] In 2016, the

terawatt hours (TWh) in 2012 to 4,500 TWh in 2040. Most of the predicted increase was expected to be in Asia.[49] As of 2018, there are over 150 nuclear reactors planned including 50 under construction.[50] In January 2019, China had 45 reactors in operation, 13 under construction, and plans to build 43 more, which would make it the world's largest generator of nuclear electricity.[51] As of 2021, 17 reactors were reported to be under construction. China built significantly fewer reactors than originally planned, its share of electricity from nuclear power was 5% in 2019[52] and observers have cautioned that, along with the risks, the changing economics of energy generation may cause new nuclear energy plants to "no longer make sense in a world that is leaning toward cheaper, more reliable renewable energy".[53][54]

In October 2021, the Japanese cabinet approved the new Plan for Electricity Generation to 2030 prepared by the Agency for Natural Resources and Energy (ANRE) and an advisory committee, following public consultation. The nuclear target for 2030 requires the restart of another ten reactors. Prime Minister Fumio Kishida in July 2022 announced that the country should consider building advanced reactors and extending operating licences beyond 60 years.[55]

As of 2022, with world oil and gas prices on the rise, while Germany is restarting its coal plants to deal with loss of Russian gas that it needs to supplement its Energiwende,

Department of Energy, in collaboration with commercial entities, TerraPower and X-energy, is planning on building two different advanced nuclear reactors by 2027, with further plans for nuclear implementation in its long term green energy and energy security goals. [58]

Power plants

An animation of a pressurized water reactor in operation
Number of electricity-generating civilian reactors by type as of 2014[59]

Nuclear power plants are thermal power stations that generate electricity by harnessing the thermal energy released from nuclear fission. A fission nuclear power plant is generally composed of: a nuclear reactor, in which the nuclear reactions generating heat take place; a cooling system, which removes the heat from inside the reactor; a steam turbine, which transforms the heat into mechanical energy; an electric generator, which transforms the mechanical energy into electrical energy.[60]

When a neutron hits the nucleus of a uranium-235 or plutonium atom, it can split the nucleus into two smaller nuclei, which is a nuclear fission reaction. The reaction releases energy and neutrons. The released neutrons can hit other uranium or plutonium nuclei, causing new fission reactions, which release more energy and more neutrons. This is called a chain reaction. In most commercial reactors, the reaction rate is contained by control rods that absorb excess neutrons. The controllability of nuclear reactors depends on the fact that a small fraction of neutrons resulting from fission are delayed. The time delay between the fission and the release of the neutrons slows down changes in reaction rates and gives time for moving the control rods to adjust the reaction rate.[60][61]

Fuel cycle

The nuclear fuel cycle begins when uranium is mined, enriched, and manufactured into nuclear fuel (1), which is delivered to a nuclear power plant. After use, the spent fuel is delivered to a reprocessing plant (2) or to a final repository (3). In nuclear reprocessing
95% of spent fuel can potentially be recycled to be returned to use in a power plant (4).

The life cycle of nuclear fuel starts with uranium mining. The uranium ore is then converted into a compact ore concentrate form, known as yellowcake (U3O8), to facilitate transport.[62] Fission reactors generally need uranium-235, a fissile isotope of uranium. The concentration of uranium-235 in natural uranium is very low (about 0.7%). Some reactors can use this natural uranium as fuel, depending on their neutron economy. These reactors generally have graphite or heavy water moderators. For light water reactors, the most common type of reactor, this concentration is too low, and it must be increased by a process called

uranium enrichment.[62] In civilian light water reactors, uranium is typically enriched to 3.5–5% uranium-235.[63]
The uranium is then generally converted into
fuel rods of the proper composition and geometry for the particular reactor.[63]

After some time in the reactor, the fuel will have reduced fissile material and increased fission products, until its use becomes impractical.[63] At this point, the spent fuel will be moved to a spent fuel pool which provides cooling for the thermal heat and shielding for ionizing radiation. After several months or years, the spent fuel is radioactively and thermally cool enough to be moved to dry storage casks or reprocessed.[63]

Uranium resources

reactors work with natural uranium.