Nuclear Power in the World Today

(Updated August 2016)

  • The first commercial nuclear power stations started operation in the 1950s.
  • There are over 440 commercial nuclear power reactors operable in 31 countries, with over 390,000 MWe of total capacity. About 60 more reactors are under construction.
  • They provide over 11% of the world's electricity as continuous, reliable base-load power, without carbon dioxide emissions.
  • 55 countries operate a total of about 245 research reactors, and a further 180 nuclear reactors power some 140 ships and submarines.

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 to 1945 research initially focussed on producing bombs which released great energy by splitting the atoms of particular isotopes of either uranium or plutonium.

In the 1950s attention turned to the peaceful purposes of nuclear fission, notably for power generation. Today, the world produces as much electricity from nuclear energy as it did from all sources combined in the early years of nuclear power. Civil nuclear power can now boast over 16,800 reactor years of experience and supplies almost 11.5% of global electricity needs, from reactors in 31 countries. In fact, through regional transmission grids, many more than those countries depend on nuclear-generated power.

Many countries have also built research reactors to provide a source of neutron beams for scientific research and the production of medical and industrial isotopes.

Today, only eight countries are known to have a nuclear weapons capability. By contrast, 55 countries operate about 245 civil research reactors, over one-third of these in developing countries. Now 31 countries host some 447 commercial nuclear power reactors with a total installed capacity of over 390,000 MWe (see linked table for up to date figures). This is more than three times the total generating capacity of France or Germany from all sources. About 60 further nuclear power reactors are under construction, equivalent to 16% of existing capacity, while over 160 are firmly planned, equivalent to nearly half of present capacity.

Nuclear Electricity Production column graph

Sixteen countries depend on nuclear power for at least a quarter of their electricity. France gets around three-quarters of its power from nuclear energy, while Belgium, Czech Republic, Finland, Hungary, Slovakia, Sweden, Switzerland, Slovenia and Ukraine get one-third or more. South Korea and Bulgaria normally get more than 30% of their power from nuclear energy, while in the USA, UK, Spain, Romania and Russia almost one-fifth 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 that level. Among countries which do not host nuclear power plants, Italy and Denmark get almost 10% of their power from nuclear.

In electricity demand, the need for low-cost continuous, reliable supply can be distinguished from peak demand occurring over few hours daily and able to command higher prices. Supply needs to match demand instantly and reliably over time. There are number of characteristics of nuclear power which make it particularly valuable apart from its actual generation cost per unit – MWh or kWh. Fuel is a low proportion of power cost, giving power price stability, and is stored onsite (not depending on continuous delivery). The power from nuclear plants is dispatchable on demand, it can be fairly quickly ramped-up, it contributes to clean air and low-CO2 objectives, it gives good voltage support for grid stability. Reactors can be made to load-follow. These attributes are mostly not monetised in merchant markets, but have great value which is increasingly recognised where dependence on intermittent sources has grown.

There is a clear need for new generating capacity around the world, both to replace old fossil fuel units, especially coal-fired ones, which contribute a lot of CO2 emissions, and to meet increased expectations for electricity in many countries. There are about 127,000 generating units worldwide, 96.5% of these of 300 MWe or less, and one-quarter of the fossil fuel plants are over 30 years old. There is scope for both large new plants and small ones to replace existing units 1:1, all with near-zero CO2 emissions.

World Nuclear Association projections made in 2016 suggest a 26.7% increase to 494 GWe in operation in 2030 and overall 40% increase to 546 GWe in 2035. (Low and high projections are 368 and 631 GWe for 2030, and 365 and 719 GWe for 2035.)

Improved performance from existing nuclear reactors

As nuclear power plant construction returns to the levels reached during the 1970s and 1980s, those plants now operating are producing more electricity. In 2011, production was 2518 billion kWh. The increase over the six years to 2006 (210 TWh) was equal to the output from 30 large new nuclear power plants. Yet between 2000 and 2006 there was no net increase in reactor numbers (and only 15 GWe in capacity). The rest of the improvement was due to better performance from existing units.

In a longer perspective, from 1990 to 2010, world capacity rose by 57 GWe (17.75%, due both to net addition of new plants and uprating some established ones) and electricity production rose 755 billion kWh (40%). The relative contributions to this increase were: new construction 36%, uprating 7% and availability increase 57%. In 2011 and 2012 both capacity and output diminished due to cutbacks in Germany and Japan following the Fukushima accident.

Considering 400 power reactors over 150 MWe for which data are available: over 1980 to 2000 world median capacity factor increased from 68% to 86%, and since then it has maintained around 85%. Actual load factors are slightly lower: 80% average in 2012 (excluding Japan), due to reactors being operated below their full capacity for various reasons. One-quarter of the world's reactors have load factors of more than 90%, and nearly two-thirds do better than 75%, compared with only about a quarter of them over 75% in 1990. The USA now dominates the top 25 positions, followed by South Korea, but six other countries are also represented there. Four of the top ten reactors for lifetime load factors are South Korean.

US nuclear power plant performance has shown a steady improvement over the past 20 years, and the average load factor in 2012 was 81%, up from 66% in 1990 and 56% in 1980. US average capacity factors have been over 90% in most years since 2000 - 92.7% in 2015. This places the USA as the performance leader with nearly half of the top 50 reactors, the 50th achieving 94% in 2015-16 (albeit without China and South Korea in those figures). The USA accounts for nearly one-third of the world's nuclear electricity.

In 2015-16, twelve countries with four or more units averaged better than 80% load factor, to which China and South Korea should probably be added, and  French reactors averaged 83%, despite many being run in load-following mode, rather than purely for base-load power.

Some of these figures suggest near-maximum utilisation, given that most reactors have to shut down every 18-24 months for fuel change and routine maintenance. In the USA this used to take over 100 days on average but in the last decade it has averaged about 40 days. Another performance measure is unplanned capability loss, which in the USA has for the last few years been below 2%.

World Electricity Production 2012 pie graph

World overview

All parts of the world are involved in nuclear power development, and a few examples follow.


The Chinese government plans to increase nuclear generating capacity to 58 GWe with 30 GWe more under construction by 2021. China has completed construction and commenced operation of over 30 new nuclear power reactors since 2002, and some 20 new reactors are under construction. These include the world's first four Westinghouse AP1000 units and a demonstration high-temperature gas-cooled reactor plant. Many more are planned, with construction due to start within about three years. China is commencing export marketing of a largely indigenous reactor design. R&D on nuclear reactor technology in China is second to none.


India’s target is to have 14.5 GWe nuclear capacity on line by 2020 as part of its national energy policy. These reactors include light- and heavy water reactors as well as fast reactors. In addition to the 22 online, of both indigenous and foreign design, five power reactors are under construction, including a 500 MWe prototype fast breeder reactor. This will take India's ambitious thorium programme to stage 2, and set the scene for eventual utilization of the country's abundant thorium to fuel reactors.


Russia plans to increase its nuclear capacity to 30.5 GWe by 2020, using its world-class light water reactors. A large fast breeder unit, the country's second, is producing power and development proceeds on others. An initial floating power plant is under construction, with delivery due in 2018. Russia leads the world in nuclear reactor exports, building and financing new nuclear power plants in several countries.


Finland and France are both expanding their fleets of nuclear power plants with the 1650 MWe EPR from Areva, two of which are also being built in China. Several countries in Eastern Europe are currently constructing or have firm plans to build new nuclear power plants (Bulgaria, Czech Republic, Hungary, Romania, Slovakia, Slovenia and Turkey).

A UK government energy paper in mid-2006 endorsed the replacement of the country’s ageing fleet of nuclear reactors with new nuclear build, and four 1600 MWe French units are planned for operation by 2023. The government aims to have 16 GWe of new nuclear capacity operating by 2030.

Sweden is closing down some older reactors, and has invested heavily in life extensions and uprates. Hungary, Slovakia and Spain are all implementing or planning for life extensions on existing plants. Germany agreed to extend the operating lives of its nuclear plants, reversing an earlier intention to shut them down, but has again reversed policy following the Fukushima accident and is phasing out nuclear generation by about 2023.

Poland is developing a nuclear program, with 6000 MWe planned. Estonia and Latvia are involved in a joint project with established nuclear power producer Lithuania. Belarus has started construction of its first two Russian reactors.

United States

In the USA, there are four reactors under construction, all new AP1000 designs. 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, changes have increased utilization of US nuclear power plants, with the increased output corresponding to 19 new 1000 MW plants being built.

South America

Argentina and Brazil both have commercial nuclear reactors generating electricity, and additional reactors are under construction. Chile has a research reactor in operation and has the infrastructure and intention to build commercial reactors.

South Korea

South Korea has three new reactors under construction domestically as well as four in the UAE. It plans for eight more. It is also involved in intense research on future reactor designs.

SE Asia

Vietnam intends to have it first nuclear power plant operating about 2028 with Russian help and a second soon after with Japanese input. Indonesia and Thailand are planning nuclear power programs.

South Asia

Bangladesh has contracted with Russia to build its first nuclear power plant. Pakistan with Chinese help is building three small reactors inland and two large ones near Karachi.

Central Asia

Kazakhstan with its abundance of uranium is working closely with Russia in planning development of small new reactors for its own use and export.

Middle East

The United Arab Emirates is building four 1450 MWe South Korean reactors at a cost of over $20 billion and is collaborating closely with IAEA and experienced international firms. Iran’s first power reactor is in operation, and more are planned.

Saudi Arabia, Jordan and Egypt are also moving towards employing nuclear energy for power and desalination.


South Africa is committed to plans for 9600 MWe of further nuclear power capacity.

Nigeria has sought the support of the International Atomic Energy Agency to develop plans for two 1000 MWe reactors.

New countries

In September 2012 the International Atomic Energy Agency (IAEA) expected seven newcomer countries to launch nuclear programs in the near term. It did not name these, but Lithuania, UAE, Turkey, Belarus, Vietnam, Poland, and Bangladesh appear likely candidates. Others had stepped back from commitment, needed more time to set up infrastructure, or did not have credible finance.

See also WNA paper Emerging Nuclear Energy Countries.

Other nuclear reactors

In addition to commercial nuclear power plants, there are about 245 research reactors operating, in 55 countries, with more under construction. These have many uses including research and the production of medical and industrial isotopes, as well as for training.

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 has 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 six large nuclear-powered icebreakers and a 62,000 tonne cargo ship. It is also completing a floating nuclear power plant with two 40 MWe reactors for use in remote regions.

Nuclear Generation by Country 2013 bar graph

Note: Taipower used nuclear energy to generate 16% of electricity on the island of Taiwan in 2014.

See table of the World's Nuclear Power Reactors with full listing of countries, which complements this paper.

WNA, data to publication date.
Nuclear Engineering International, (load factors)

You may also be interested in