A recent report – Energy, Electricity, and Nuclear Power Estimates for the Period up to 2050 (2021 Edition) – published by the International Atomic Energy (IAEA) highlights the fact that the global population of 7,795 millions in 2020: 

Source: International Atomic Energy Agency (IAEA)

The conclusions of the overview are organized into the following categories:

  1. World and Regional Subsections (Column 1): This reflects 10 Regions around the world plus World;
  2. Millions of People (Column 2): It shows how many people in each region as well as in the world;
  3. % of Electricity Consumed (Column 3): It shows the percentage of the total energy consumed by the millions people in each region as well as in the world;
  4. Electricity Produced (TW.h) Column 4): It shows the electricity produced in each region as well as in the world in “energy units” as each Terawatt-hour (TW.h) is equivalent to 1,000,000,000; and
  5. Nuclear Percentage (Column 5): It shows the percentage of the electricity produced with nuclear in each region as well as in the world. The percentage for the world is an average of all regions.

Here is a graph which illustrates the percentage of nuclear electricity generated and used in the respective countries:

Source: International Atomic Energy Agency (IAEA)

Here are some other facts about Nuclear Power Development in 2020:

  1. At the end of 2020, 442 nuclear power reactors were operational around the world with a total net installed power capacity of 392.6 GW (e);
  2. In addition, 52 nuclear power reactors with a total capacity of 54.4 GW(e), were under construction;
  3. Five new nuclear power reactors with a total capacity of 5,521 MW(e) were connected to the grid;
  4. Six nuclear power reactors with a total capacity of 5,165(e) were retired;
  5. Construction began on four new nuclear power reactors that are expected to add a total capacity of 4,473(e);
  6. Compared with 2019, total electricity production from all energy sources decreased by 2% and electricity production from nuclear power reactors decreased about 4% to 2,553 TW.h; and
  7. Nuclear power accounted for 10.2% of total electricity production in 2020, a decrease of 0.2% from the previous year. 

The COVID-19 Pandemic had a profound impact on the energy sector and on the global economy.  The reduction in global electricity demand was the biggest annual decline since the mid-20th century.  Nevertheless, statistical estimates based on energy production data for the first half of 2021 suggest that energy consumption could rebound and exceed figures for 2019.

Nuclear technology was first developed in the 1940s, and during the Second World War it was used for 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.

Nuclear energy is defined as a source of power which is created from energy released by a nuclear reaction. Nuclear reactors serve three general purposes:

  1.  Civilian Reactors are used to generate energy for electricity and sometimes also steam for district heating; military reactors create materials that can be used in nuclear weapons; and research reactors are used to develop weapons or energy production technology, for training purposes, for nuclear physics experimentation, and for producing radio-isotopes for medicine and research;

Source: C&EN

2.  Military Reactors create materials that can be used in nuclear weapons; and


3.  Research Reactors are used to develop weapons or energy production technology, for training purposes, for nuclear physics experimentation, and for producing radio-isotopes for medicine and research. The chemical composition of the fuel, the type of coolant, and other details important to reactor operation depend on reactor design. Most designs have some flexibility as to the type of fuel that can be used. Some reactors are dual-purpose in that they are used for civilian power and military materials production. The two tables below give information about civilian and military reactors.


The focus of this book is on the Civilian and Research Reactors.

The global demand for electricity will continue to intensify and in order to meet this demand, future electricity generation will need a range of options and these options must be low carbon if the global objective is to reduce greenhouse gas (GHG) emissions significantly.  The good news is that nuclear generation provides reliable supplies of electricity, with very low carbon emissions and relatively small amounts of waste that can be safely stored and eventually disposed of.

The reality is that each method opted to generate electricity, generates GHGs in varying quantities throughout the life cycle – construction, operation, and decommissioning.  Some generation methods such as coal fired power plants release the majority of GHGs when their carbon-containing fossil fuels are burnt, producing carbon dioxide (CO2). Others, such as wind power and nuclear power, give rise to much less emissions, these being during construction and decommissioning, or mining and fuel preparation in the case of nuclear.  Comparing the lifecycle emissions of electrical generation allows for a fair comparison of the different generation methods on a per kilowatt-hour basis. The lower the value, the fewer GHG emissions are released.

Here is an important consideration.  Nuclear power plants produce no GHG emissions during operation, and over the course of its life-cycle, nuclear produces about the same amount of carbon dioxide-equivalent emissions per unit of electricity as wind, and one-third of the emissions per unit of electricity when compared with solar.

Average life-cycle carbon dioxide-equivalent emissions for different electricity generators (Source: IPCC)

Perhaps another important if not critical factor about the generation of nuclear electricity is the cost.  Here is a graph designed to illustrate the breakdown of Operating Costs associated with Coal, Gas, and Gas Generation:

It should be kept in mind that nuclear technology is not just used to supply electricity to the grid; it is in a wide variety of other uses such as medicine, heating and space travel.  For instance:

  • Nuclear Medicine:  Nuclear medicine uses radiation to allow doctors to make a quick, accurate diagnosis of the functioning of person’s specific organs, or to treat them. Radiotherapy can be used to treat some medical conditions, especially cancer, using radiation to weaken or destroy particular targeted cells.
    • Tens of millions of patients are treated with nuclear medicine each year;
    • Over 10,000 hospitals worldwide use radioisotopes in medicine, and about     90  percent of the procedures are for diagnosis.  The most common radioisotope used in diagnosis is technetium-99, with some 30 million procedures per year, accounting for 80 percent of all nuclear medicine procedures worldwide; and
    • Modern industry also uses radioisotopes in a variety of ways. Sealed radioactive   sources are used in industrial radiography, gauging applications and mineral analysis.
  • Heat for Desalination: Heat from nuclear reactors can be used directly, instead or as well as being used to generate electricity. This heat can be used for district heating, as process heat for industry or for desalination plants, used to make clean drinkable water from seawater; and
  • Space Missions:  Radioisotope thermal generators are used in space missions. The heat generated by the decay of a radioactive source, often Plutonium-238, is used to generate electricity.  The Voyager space probes, the Cassini mission to Saturn, the Galileo mission to Jupiter and the New Horizons mission to Pluto all are powered by RTGs. The Spirit and Opportunity Mars rovers have used a mix of solar panels for electricity and RTGs for heat. The latest Mars rover, Curiosity, is much bigger and uses RTGs for heat and electricity as solar panels would not be able to supply enough electricity.

In the future electricity or heat from nuclear power plants could be used to make hydrogen. Hydrogen can be used in fuel cells to power cars, or can be burnt to provide heat in place of gas, without producing emissions that would cause climate change.

Updated on 21 October 2021.

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