What is the history of nuclear energy?  

The Earth's uranium was produced through collisions and supernovae of stars billions of years ago, but uranium was not discovered until 1789, and ionizing radiation not until 1895.

In 1896, Henri Becquerel found that a uranium-rich mineral ore emitted radiation, later named ‘radioactivity’ by Pierre and Marie Curie.

In 1938, German scientists Otto Hahn and Fritz Strassmann developed an experiment to split atoms – explained by Lise Meitner and Otto Robert Frisch, who named the reaction ‘fission’.

Fission Fact: Around two billion years ago, in what is now Oklo in Gabon, West Africa, fission occurred in a rich deposit of uranium ore. At that time, natural uranium was concentrated with more fissile material which allowed a self-sustaining reaction to occur. Read more in The Cosmic Origins of Uranium

Following the discovery of fission, wartime research in Europe and the North America rapidly turned this into weapons capability. This Manhattan Project led to the first atomic weapons used in 1945 (Hiroshima and Nagasaki).

The Cold War powers expanded their national nuclear programmes to maintain strategic capability and avoid falling behind in an intensively competitive environment.

After World War II, governments pursued peaceful applications of nuclear energy:  the USA and Russia demonstrated electricity generation from nuclear reactors, and following US President Eisenhower’s ‘Atoms for Peace’ speech, international cooperation on safety, safeguards, and non‑proliferation soon expanded through the creation of the International Atomic Energy Agency (IAEA).

These events helped to shape modern nuclear energy and the global non‑proliferation framework.

Fission Fact: A major development came in December 1942, when the first human-made self-sustaining nuclear chain reaction was demonstrated at Chicago Pile-1 in an experiment led by Enrico Fermi.

In 1954 the Soviet Union was the first country to put nuclear generated electricity onto the power grid at the Obninsk Atom Mirny (‘Peaceful Atom’) reactor, which had a capacity of around 5 MWe. In 1956, the UK was the first to build a full-scale nuclear power plant at Calder Hall (four units of 60 MWe each). And in 1957 the USA was the first to launch a commercial pressurized water reactor (60 MWe) at Shippingport, Pennsylvania.

Following the 1970s oil crisis, many countries expanded the use of nuclear through strategic build programmes, notably France, Japan and Sweden. Nuclear was recognised as an alternative electricity source to oil with much less vulnerability to supply shocks, strengthening nations’ energy security.  World Nuclear Association’s forerunner organization, the Uranium Institute was formed in 1975 as demand for uranium began to rise.

Fission Fact: Globally, most countries adopted light-water reactors, leading to around 90% of nuclear capacity being water-cooled reactors today.

From the early 1980s to the 2000s, nuclear power faced stagnation. Following serious accidents at Three Mile Island in March 1979 and Chernobyl in April 1986, construction of new reactors slowed in the West and uranium production declined.

In response to these accidents, international organizations, industry and regulators worked together to share knowledge and continuously improve operations and safety—work that continues today.

By the late 1990s, the first of the third-generation reactors entered service: Kashiwazaki-Kariwa 6 in Japan (a 1350 MWe Advanced BWR), signalling the shift towards newer reactor designs and expansion of nuclear programmes in Asia.

In the 2000s, interest in new nuclear grew globally again, driven by rising electricity demand, energy security concerns, and the need to cut carbon emissions. However, the Fukushima Daiichi accident in March 2011 paused this momentum as several countries reassessed nuclear policy.

Fission Fact: Average reactor capacity factors have risen steadily since the 1970s, with the greatest improvements taking place in the 1980s and ’90s as industry shared experience, and improved operational performance.

Today there has been a resurgence of interest in nuclear energy and a clear need for new generating capacity around the world. Thirty-eight countries have now signed the Declaration to Triple Nuclear Energy Capacity by 2050 at a time when energy security concerns have once again highlighted the need for nuclear energy.

The World Bank and other multilateral development banks have revised lending policies to include nuclear energy projects, and major financial institutions have affirmed their support for nuclear expansion. Nuclear energy is increasingly being identified to power industrial decarbonization too, for applications such as data centres, petrochemical, metallurgical and desalination plants.

Read more in the information library: Nuclear Power in the World Today

Fission Fact: Over the past five decades, around 20,000 reactor-years of operation have contributed to global electricity supply while  avoiding over a gigatonne (Gt) of global carbon dioxide emissions annually (Nuclear Power and Secure Energy Transitions, International Energy Agency, 2022).