Nuclear power and weapons in the world

Nuclear power plants

Another 23 reactors are idle (shut down but not closed, mostly in Japan after Fukushima) and 465 are planned or announced. Global Energy Monitor, August 2026; cancelled or shelved projects are not counted.

Reactors in operation, year by year

Reactors started and not yet closed in each year, including those idle today; from the start and closure years in the Global Energy Monitor data.

Countries with nuclear reactors

Countries that have or have had at least one reactor (in operation, idle, under construction or closed). GW: capacity of the reactors in operation. First reactor: start year of the first grid-connected reactor. Global Energy Monitor, August 2026.

Nuclear tests

Since the first test in the New Mexico desert (16 July 1945) the nuclear powers have exploded more than 2,000 test bombs. After the 1963 Treaty banning tests in the atmosphere, in space and under water, nearly all were carried out underground.

Arms Control Association, “The Nuclear Testing Tally”, October 2025. The United States has 1,054 counting the tests carried out jointly with the United Kingdom.

Where the atmospheric tests took place

On the map the atmospheric tests are grouped by test site, not shown one by one; locations are approximate (the centre of the area). Missing are 7 US tests in the open ocean (4 in the Pacific, 3 at high altitude over the South Atlantic) and 12 Soviet tests at other sites (Kapustin Yar, Totskoye and others), which the sources do not allow us to count site by site. They include air, surface, underwater and high-altitude tests. Hiroshima and Nagasaki were not tests and are not counted.

Recorded underground tests, year by year

The 1,005 underground nuclear explosions recorded by seismographs in the USGS catalog (1951–2017): about two thirds of the underground tests, because smaller or older ones are not always in the catalog. Who carried out each test is inferred from the place.

The most serious accidents

Nuclear and radiological accidents rated level 4 or higher on the INES scale, from the most serious. * = level assigned later, because the accident happened before 1990, when the scale did not yet exist, or because there is no official rating.

1. 7*

   Chernobyl, unit 4 Pripyat, Ukraine · 26 April 1986

   An explosion and fire destroyed reactor 4; radioactivity spread over much of Europe.

   Sources: AERB, Annual Report 2019 (INES) · ASN, Échelle INES (2013) · OFPP/BABS, Dossier de danger «Accident dans une centrale nucléaire»

   On the map
2. 7

   Fukushima Daiichi Ōkuma and Futaba, Japan · 11 March 2011

   The tsunami caused by the earthquake cut power and cooling to the reactors; explosions destroyed the buildings of reactors 1, 2 and 3. Japan assigned level 7 on 12 April 2011 (previously 5).

   Sources: TEPCO, 12.4.2011 · AERB, Annual Report 2019 (INES) · ASN, Échelle INES (2013)

   The 2011 earthquake The 2011 tsunami

   On the map
3. 6*

   Kyshtym (Mayak plant) Ozyorsk, Russia · 29 September 1957 · approximate location

   The chemical explosion of a radioactive waste tank contaminated a large area: 22 villages with more than 10,000 inhabitants were evacuated.

   Sources: Akleyev et al., J. Radiol. Prot. 37 (2017) · IAEA/OECD-NEA, INES (1999) · AERB, Annual Report 2019 (INES)

   On the map
4. 5*

   Windscale, Pile 1 fire Seascale (now Sellafield), United Kingdom · 1957

   The graphite core of the reactor caught fire during a routine operation and released radioactive iodine.

   Sources: IAEA/OECD-NEA, INES (1999) · AERB, Annual Report 2019 (INES) · ASN, Les cahiers Histoire de l’ASN 1

   On the map
5. 5*

   Three Mile Island, unit 2 Middletown, Pennsylvania, United States of America · 28 March 1979

   A stuck-open valve and operator errors led to a severe core meltdown; the containment held and little radioactivity escaped.

   Sources: US NRC, Three Mile Island Accident · IAEA/OECD-NEA, INES (1999) · AERB, Annual Report 2019 (INES)

   On the map
6. 5*

   Goiânia, caesium-137 source Goiânia, Brazil · 1987 · approximate location

   Scavengers recovered a radioactive caesium-137 source and several people were irradiated.

   Sources: AERB, Annual Report 2019 (INES) · ASN, Échelle INES (2013) · US NRC, INES (2009)

   On the map
7. 4*

   Saint-Laurent-des-Eaux A1 Loir-et-Cher, France · 1969

   During fuel loading 47 kg of uranium (five fuel elements) melted in the gas-graphite reactor.

   Sources: ASN, Échelle INES (2013) · ASN, Les cahiers Histoire de l’ASN 1

   On the map
8. 4–5*

   Lucens, experimental plant Lucens, Vaud, Switzerland · 21 January 1969

   A pressure tube ruptured and the reactor core partly melted; almost all the radioactivity stayed in the rock cavern. There is no official rating: sources give level 4 or 5.

   Sources: OFPP/BABS, Dossier de danger «Accident dans une centrale nucléaire» · SRF, 50 Jahre Lucens (2019) · ASN, Les cahiers Histoire de l’ASN 1

   On the map
9. 4*

   Windscale, reprocessing plant Seascale (now Sellafield), United Kingdom · 26 September 1973

   A reaction in a reprocessing vessel released radioactive material inside the plant: level 4 for the on-site consequences.

   Sources: Hansard, 19.10.1973 · IAEA/OECD-NEA, INES (1999) · ASN, Échelle INES (2013)

   On the map
10. 4*

    Saint-Laurent-des-Eaux A2 Loir-et-Cher, France · 1980

    A metal plate blocked the cooling channels and about 20 kg of uranium melted, with no release outside.

    Sources: IAEA/OECD-NEA, INES (1999) · ASN, Échelle INES (2013)

    On the map
11. 4*

    RA-2 research reactor Constituyentes Atomic Centre, Buenos Aires, Argentina · 23 September 1983 · approximate location

    An operator changed the core without draining the water: the sudden chain reaction irradiated him and he died two days later.

    Sources: US NRC, Information Notice 83-66 · IAEA/OECD-NEA, INES (1999)

    On the map
12. 4

    Tokaimura, JCO fuel plant Tōkai, Ibaraki, Japan · 30 September 1999 · approximate location

    Workers poured far too much enriched uranium into a vessel: the chain reaction lasted about 20 hours and two of the three irradiated workers died.

    Sources: World Nuclear Association, Tokaimura · AERB, Annual Report 2019 (INES) · ASN, Échelle INES (2013)

    On the map
13. 4

    Fleurus, Institut national des radioéléments Fleurus, Belgium · 2006 · approximate location

    Accident at the Belgian institute that produces radioactive substances.

    Sources: AERB, Annual Report 2019 (INES)

    On the map
14. 4

    Mayapuri, radioactive scrap New Delhi, India · 2010 · approximate location

    Radioactive scrap at a metal market irradiated a scrap dealer.

    Sources: AERB, Annual Report 2019 (INES) · ASN, Échelle INES (2013)

    On the map
15. 4

    Cobalt-60 source sterilisation plant, Bulgaria · 2011 · exact place not given in the sources

    A cobalt-60 source at a sterilisation plant irradiated four workers.

    Sources: ASN, Échelle INES (2013)

Only events rated level 4 or higher that appear in the official INES lists (IAEA examples and nuclear safety authorities); Lucens is added for its importance in Switzerland, although it has no official rating. Where the sources do not give the exact day, only the year is shown.

The indicators

• Energy How much electricity comes from nuclear power in each country
• Nuclear power plants The power plants on the map, with the other layers

Sources: Global Energy Monitor, Global Nuclear Power Tracker, August 2026 (CC BY 4.0); USGS earthquake catalog (public domain); Arms Control Association, The Nuclear Testing Tally (October 2025); for test sites and accidents the sources are given case by case.