• The first commercial nuclear power stations started operation in the 1950s.
• Nuclear energy now provides about 11% of the world's electricity from about 450 power reactors.
• Nuclear is the world's second largest source of low-carbon power (30% of the total in 2016). 
• Over 50 countries utilise nuclear energy in about 225 research reactors. In addition to research, these reactors are used for the production of medical and industrial isotopes, as well as for training. 

Nuclear technology uses the energy released by splitting the atoms of certain elements. It was first developed in the 1940s, and during the Second World War research initially focused on producing bombs. In the 1950s attention turned to the peaceful use of nuclear fission, controlling it for power generation. For more information, see page on History of Nuclear Energy.

Civil nuclear power can now boast more than 17,000 reactor years of experience, and nuclear power plants are operational in 30 countries worldwide. In fact, through regional transmission grids, many more countries depend in part on nuclear-generated power; Italy and Denmark, for example, get almost 10% of their electricity from imported nuclear power.

Number of Operable Reactors Worldwide

 

Around 11% of the world's electricity is generated by about 450 nuclear power reactors. About 60 more reactors are under construction, equivalent to about 15% of existing capacity.

In 2017 nuclear plants supplied 2487 TWh of electricity, up from 2477 TWh in 20161. This is the fifth consecutive year that global nuclear generation has risen, with output 142 TWh higher than in 2012.

Nuclear Electricity Production

World Electricity Production by Source 2016

Thirteen countries in 2017 produced at least one-quarter of their electricity from nuclear. France gets around three-quarters of its electricity from nuclear energy; Hungary, Slovakia and Ukraine get more than half from nuclear, whilst Belgium, Sweden, Slovenia, Bulgaria, Switzerland, Finland and Czech Republic get one-third or more. South Korea normally gets more than 30% of its electricity from nuclear, while in the USA, UK, Spain, Romania and Russia about one-fifth of electricity is from nuclear. Japan is used to relying on nuclear power for more than one-quarter of its electricity and is expected to return to somewhere near that level. 

Nuclear Generation by Country 2018

Need for new generating capacity

There is a clear need for new generating capacity around the world, both to replace old fossil fuel units, especially coal-fired ones, which emit a lot of carbon dioxide, and to meet increased demand for electricity in many countries. In 2016, 65.0% of electricity was generated from the burning of fossil fuels. Despite the strong support for, and growth in, intermittent renewable electricity sources in recent years, the fossil fuel contribution to power generation has remained virtually unchanged in the last 10 years or so (66.5% in 2005).

The OECD International Energy Agency publishes annual scenarios related to energy. In its World Energy Outlook 20182 there is an ambitious ‘Sustainable Development Scenario’ which is consistent with the provision of clean and reliable energy and a reduction of air pollution, among other aims. In this decarbonisation scenario, electricity generation from nuclear increases by almost 90% by 2040 to 4960 TWh, and capacity grows to 678 GWe. The World Nuclear Association has put forward a more ambitious scenario than this – the Harmony programme proposes the addition of 1000 GWe of new nuclear capacity by 2050, to provide 25% of electricity then (about 10,000 TWh) from 1250 GWe of capacity (after allowing for 150 GWe retirements). This would require adding 25 GWe per year from 2021, escalating to 33 GWe per year, which is not much different from the 31 GWe added in 1984, or the overall record of 201 GWe in the 1980s. Providing one-quarter of the world's electricity through nuclear would substantially reduce carbon dioxide emissions and have a very positive effect on air quality.

World overview

All parts of the world are involved in nuclear power development, and some examples are outlined below.

For up-to-date data on operable, under construction and planned reactors worldwide, see table of World Nuclear Power Reactors & Uranium Requirements.

For detailed country-level information, see the Country Profiles section of World Nuclear Association's Information Library.

North America

Canada has 19 operable nuclear reactors, with a combined net capacity of 13.5 GWe. In 2017, nuclear generated 15% of the country's electricity.

All but one of the country's 19 nuclear reactors are sited in Ontario. In the first part of 2016 the government signed major contracts for the refurbishment and operating lifetime extension of six reactors at the Bruce generating station. The programme will extend the operating lifetimes by 30-35 years. Similar refurbishment work enabled Ontario to phase out coal in 2014, achieving one of the cleanest electricity mixes in the world.

Mexico has two operable nuclear reactors, with a combined net capacity of 1.6 GWe. In 2017, nuclear generated 6% of the country's electricity.

The USA has 98 operable nuclear reactors, with a combined net capacity of 99.4 GWe. In 2017, nuclear generated 20% of the country's electricity.

There had been four AP1000 reactors under construction, but two of these have been halted. One of the reasons for the hiatus in new build in the USA to date has been the extremely successful evolution in maintenance strategies. Over the last 15 years, improved operational performance has increased utilisation of US nuclear power plants, with the increased output equivalent to 19 new 1000 MWe plants being built.

2016 saw the first new nuclear power reactor enter operation in the country for 20 years. Despite this, the number of operable reactors has reduced in recent years, from a peak of 104 in 2012. Early closures have been brought on by a combination of factors including cheap natural gas, market liberalization, over-subsidy of renewable sources, and political campaigning.  

South America

Argentina has three reactors, with a combined net capacity of 1.7 GWe. In 2017, the country generated 5% of its electricity from nuclear. 

Brazil has two reactors, with a combined net capacity of 1.9 GWe. In 2017, nuclear generated 3% of the country's electricity.  

West & Central Europe

Belgium has seven operable nuclear reactors, with a combined net capacity of 5.9 GWe. In 2017, nuclear generated 50% of the country's electricity.

Finland has four operable nuclear reactors, with a combined net capacity of 2.8 GWe. In 2017, nuclear generated 33% of the country's electricity. A fifth reactor – a 1720 MWe EPR – is under construction, and there are plans to build a Russian VVER-1200 unit at a new site (Hanhikivi).

France has 58 operable nuclear reactors, with a combined net capacity of 63.1 GWe. In 2017, nuclear generated 72% of the country's electricity.

A 2015 energy policy had aimed to reduce the country's share of nuclear generation to 50% by 2025. In November 2017, the French government postponed this target. The country's energy minister said that the target was not realistic, and that it would increase the country's carbon dioxide emissions, endanger security of supply and put jobs at risk.

One reactor is currently under construction in France – a 1750 MWe EPR at Flamanville.

In Germany, seven nuclear power reactors continue to operate, with a combined net capacity of 9.4 GWe. In 2017, nuclear generated 12% of the country's electricity.

Germany is phasing out nuclear generation by about 2022 as part of its Energiewende policy. Energiewende, widely identified as the most ambitious national climate change mitigation policy, has yet to deliver a meaningful reduction in carbon dioxide (CO2) emissions. In 2011, the year after the policy was introduced, Germany emitted 731 Mt CO2from fuel combustion; in 2015, the country emitted 730 Mt CO2, and remained the world's sixth-biggest emitter of CO2.3 The German government expects to miss its target of a 40% reduction in emissions relative to 1990 levels by a wide margin.

The Netherlands has a single operable nuclear reactor, with a net capacity of 0.5 GWe. In 2017, nuclear generated 3% of the country's electricity.

Spain has seven operable nuclear reactors, with a combined net capacity of 7.1 GWe. In 2017, nuclear generated 21% of the country's electricity.

Sweden has eight operable nuclear reactors, with a combined net capacity of 8.4 GWe. In 2017, nuclear generated 40% of the country's electricity.

The country is closing down some older reactors, but has invested heavily in operating lifetime extensions and uprates.

Switzerland has five operable nuclear reactors, with a combined net capacity of 3.3 GWe. In 2017, nuclear generated 33% of the country's electricity.

The UK has 15 operable nuclear reactors, with a combined net capacity of 8.9 GWe. In 2017, nuclear generated 19% of the country's electricity. 

A UK government energy paper in mid-2006 endorsed the replacement of the country’s ageing fleet of nuclear reactors with new nuclear build. Construction has commenced on the first of some 12.5 GWe of new-generation plants.

Central and East Europe, Russia

Armenia has a single nuclear power reactor with a net capacity of 0.4 GWe. In 2017, nuclear generated 33% of the country's electricity. 

Belarus has its first nuclear power plant under construction, and plans to have the first of two Russian reactors operating by 2019. At present almost all of the country's electricity is produced from natural gas.

Bulgaria has two operable nuclear reactors, with a combined net capacity of 1.9 GWe. In 2017, nuclear generated 34% of the country's electricity.

The Czech Republic has six operable nuclear reactors, with a combined net capacity of 3.9 GWe. In 2017, nuclear generated 33% of the country's electricity.

Hungary has four operable nuclear reactors, with a combined net capacity of 1.9 GWe. In 2017, nuclear generated 50% of the country's electricity.

Romania has two operable nuclear reactors, with a combined net capacity of 1.3 GWe. In 2017, nuclear generated 18% of the country's electricity.

Russia has 36 operable nuclear reactors, with a combined net capacity of 28.0 GWe. In 2017, nuclear generated 18% of the country's electricity.

A government decree in 2016 specified construction of 11 nuclear power reactors by 2030, in addition to those already under construction. At the start of 2019, Russia had six reactors under construction, with a combined capacity of 4.9 GWe.

The strength of Russia's nuclear industry is reflected in its dominance of export markets for new reactors. The country's national nuclear industry is currently involved in new reactor projects in Belarus, China, Hungary, India, Iran and Turkey, and to varying degrees as an investor in Algeria, Bangladesh, Bolivia, Indonesia, Jordan, Kazakhstan, Nigeria, South Africa, Tajikistan and Uzbekistan among others.

Slovakia has four operable nuclear reactors, with a combined net capacity of 1.8 GWe. In 2017, nuclear generated 54% of the country's electricity. A further two units are under construction, with the first unit due to enter commercial operation before the end of the decade.

Slovenia has a single operable nuclear reactor with a net capacity of 0.7 GWe. In 2017, Slovenia generated 39% its electricity from nuclear.

Ukraine has 15 operable nuclear reactors, with a combined net capacity of 13.1 GWe. In 2017, nuclear generated 55% of the country's electricity.

Turkey commenced construction of its first nuclear power plant in April 2018, with start of operation expected in 2023.

Asia

Bangladesh started construction on the first of two planned Russian VVER-1200 reactors in 2017. It plans to have the first unit in operation by 2023. The country currently produces virtually all of its electricity from fossil fuels.

China has 45 operable nuclear reactors, with a combined net capacity of 43.0 GWe. In 2017, nuclear generated 4% of the country's electricity.

The country continues to dominate the market for new nuclear build. At the start of 2019, 13 of the 57 reactors under construction globally were in China. In 2018 China became the first country to commission two new designs – the AP1000 and the EPR. China is commencing export marketing of the Hualong One, a largely indigenous reactor design.

The strong impetus for developing new nuclear power in China comes from the need to improve urban air quality and reduce greenhouse gas emissions. The government's stated long-term target, as outlined in its Energy Development Strategy Action Plan 2014-2020 is for 58 GWe capacity by 2020, with 30 GWe more under construction.

India has 22 operable nuclear reactors, with a combined net capacity of 6.2 GWe. In 2017, nuclear generated 3% of the country's electricity.

The Indian government is committed to growing its nuclear power capacity as part of its massive infrastructure development programme. The government in 2010 set an ambitious target to have 14.6 GWe nuclear capacity online by 2024. At the start of 2019 seven reactors were under construction in India, with a combined capacity of 5.4 GWe.

Japan has 37 operable nuclear reactors, with a combined net capacity of 36.1 GWe. At the start of 2019, only nine reactors had been brought back online, with a further 17 in the process of restart approval, following the Fukushima accident in 2011. In the past, 30% of the country's electricity has come from nuclear; in 2017, the figure was just 4%.

South Korea has 23 operable nuclear reactors, with a combined net capacity of 22 GWe. In 2017, nuclear generated 27% of the country's electricity.

South Korea has four new reactors under construction domestically as well as four in the United Arab Emirates. It plans for two more, after which energy policy is uncertain. It is also involved in intense research on future reactor designs.

Pakistan has five operable nuclear reactors, with a combined net capacity of 1.4 GWe. In 2017, nuclear generated 6% of the country's electricity. Pakistan has two Chinese Hualong One units under construction.

Africa

South Africa has two operable nuclear reactors, with a combined net capacity of 1.8 GWe, and is the only African country currently producing electricity from nuclear. In 2017, nuclear generated 7% of the country's electricity. South Africa remains committed to plans for further capacity, but financing constraints are significant.

Middle East

Iran has a single operable nuclear reactor with a net capacity of 0.9 GWe. In 2017, nuclear generated 2% of the country's electricity. 

The United Arab Emirates is building four 1450 MWe South Korean reactors at a cost of over $20 billion, and is collaborating closely with the International Atomic Energy Agency and experienced international firms.

Emerging nuclear energy countries

As outlined above, Bangladesh, Belarus, Turkey and the United Arab Emirates are all constructing their first nuclear power plants. A number of other countries are moving towards use of nuclear energy for power production. For more information, see page on Emerging Nuclear Energy Countries.

Improved performance from existing reactors

The performance of nuclear reactors has improved substantially over time. Over the last 40 years the proportion of reactors reaching high capacity factors has increased significantly. For example, 64% of reactors achieved a capacity factor higher than 80% in 2016, compared to 24% in 1976, whereas only 8% of reactors had a capacity factor lower than 50% in 2016, compared to 22% in 1976.

Long-term Trends in Capacity Factors

It is also notable that there is no significant age-related trend in the mean capacity factor for reactors over the last five years.

Mean Capacity Factor 2012-2017 by Age of Reactor

Other nuclear reactors

In addition to commercial nuclear power plants, there are about 225 research reactors operating in over 50 countries, with more under construction. As well as being used for research and training, many of these reactors produce medical and industrial isotopes.

The use of reactors for marine propulsion is mostly confined to the major navies where it has played an important role for five decades, providing power for submarines and large surface vessels. At least 140 ships, mostly submarines, are propelled by some 180 nuclear reactors and over 13,000 reactor years of experience have been gained with marine reactors. Russia and the USA have decommissioned many of their nuclear submarines from the Cold War era.

Russia also operates a fleet of four large nuclear-powered icebreakers and has three more under construction. It is also completing a floating nuclear power plant with two 40 MWe reactors adapted from those powering icebreakers for use in remote regions.

For more information see page on The Many Uses of Nuclear Technology.