Working together to ensure reliable, affordable and clean energy

energy Russia energy china flag

FAQs: Nuclear

What is nuclear energy?

All elements in the universe are made of atoms. An atom is composed of a nucleus and electrons. A nucleus is composed of neutrons and protons. Some nuclei are stable, and some undergo spontaneous radioactive decay. Radioactive decay can also be induced by interaction with neutrons or other particles.

In nuclear reactors, heat is produced by fission of fissile nuclear materials like uranium-235. In this case, fission is induced when the nucleus absorbs a neutron, causing it to split apart. This produces fission products, including free neutrons, which can then split other uranium-235 nuclei. This chain reaction produces heat, via radiation, and the slowing down of fission products as they impact the fuel around them. Nuclear reactors are designed to convert this heat into electricity, like in any other thermal power plant. To avoid overheating, the plants incorporate cooling systems.

Nuclear fusion is another type of nuclear reaction in which extra energy is released when light nuclei are fused together. This type of reaction produces heat in the sun and other stars. Unlike the nuclear fission process, extreme temperatures and pressure are needed to initiate and sustain the fusion reaction. Because of this, it is challenging to maintain fusion reactions in laboratory conditions. However, research and development aimed at achieving controlled fusion has been pursued for many years with significant advances in recent decades.

Nuclear Energy Today provides further explanation on the nuclear power technology.


What is the history of nuclear energy?

The generation of electricity using nuclear energy was first demonstrated in the 1950s, and the first commercial nuclear power plants entered operation in the early 1960s. Nuclear capacity grew rapidly in the 1970s and 1980s as countries sought to reduce dependence on fossil fuels, especially after the oil crises of the 1970s. However, with the exception of Japan and Korea, growth stagnated in the 1990s. Reasons for this included increased concerns about safety following accidents in the Three Mile Island (1979) and Chernobyl (1986), delays and higher-than-expected construction costs at some nuclear plants, and a return to lower fossil fuel prices.

However, from 2000, there was a renewed interest in nuclear power, and the pace of construction accelerated after 2005. At the end of 2010, there were 65 reactors under construction, and 60 new countries had expressed interest in launching a nuclear programme to the International Atomic Energy Agency (IAEA). The International Conference on Access to Civil Nuclear Energy, co-organised by the French Government and the OECD/Nuclear Energy Agency (NEA) in March 2010 at the OECD Conference Centre, symbolised this change of attitude, with more than 60 countries represented, 43 ministers and 1 200 participants.

Then, in March 2011, a major earthquake and tsunami ravaged the Pacific coast of northern Japan and damaged the cooling system at the Fukushima Daiichi nuclear power plant, resulting in a severe accident. No deaths have been attributed to the accident (while the tsunami and the earthquake killed 20,000 people), but serious releases of radioactive material resulted in contamination of the surrounding environment and led to the evacuation of several thousand inhabitants from their homes. In reaction, most nuclear countries announced safety reviews of their nuclear reactors (stress tests) and the revision/improvement of their plans to address similar emergency situations, including in the framework of the G8-OECD/NEA Ministerial Seminar on Nuclear Safety and Forum of Regulators of June 2011.

The impact on the growth of nuclear generating capacity will become fully clear only in the coming years A majority of countries have confirmed their construction plans (including China, the Emirates, France, Poland, the United Kingdom and the United States) while a limited number of others (essentially Germany and Italy) have decided to eventually phase out nuclear power or to abandon their nuclear plant projects.


Can nuclear power be widely deployed?

Yes. The present status of nuclear energy technology is the result of over 50 years of development and operational experience. Nuclear power is a mature, low-carbon technology that is available today for wider deployment, subject to safety and security conditions. Refer to the IEA-NEA Nuclear Energy Technology Roadmap for more information.


Are technologies under development for the next generation of nuclear systems?

Yes. Several technologies under development offer the potential for improved sustainability, economics, proliferation resistance, safety and reliability. Some will be suited to a wider range of locations and to potential new applications. Each involves a significant technological step, such as passive cooling, which cannot be disrupted, and will require full-scale demonstration before commercial deployment. Such systems could start to make a contribution to nuclear capacity from 2040.


How much electricity supply does nuclear energy represent in the OECD area?

Almost 22%.


Are uranium resources available in sufficient quantities?

The uranium resource base described in the IAEA-NEA publication Uranium 2009: Resources, Production and Demand is more than adequate to meet projected requirements. Meeting even high-case global demand scenario requirements to 2035 outlined in this publication (782 Gigawatt electric net) would consume less than half of the identified resources documented in 2009. First elements from the compilation of data for the 2011 edition of this publication indicate that the uranium resource base remains more than adequate to meet projected demand to 2035 and beyond.


What is fission?

A reaction when the nucleus of an atom, having captured a neutron, splits into two or more nuclei, and in so doing, releases a significant amount of energy, as well as more neutrons. These neutrons then go on to split more nuclei and a chain reaction takes place.


What is fusion?

Fusion is a process whereby two hydrogen nuclei collide and join together to form a heavier atom, usually deuterium and tritium. When this happens a considerable amount of energy gets released at extremely high temperatures: nearly 150 million °C. At extreme temperatures, electrons are separated from nuclei and a gas becomes a plasma – a hot, electrically charged gas. A plant producing electricity from a nuclear fusion reaction could replace nuclear fission plants. The fuel is abundant (deuterium, lithium and tritium), with very little radioactivity and low radioactivity of the components with a short half-life, no need for underground storage, and no environmental risk in case of accident, as plasma cannot exist without being confined in a chamber under high pressure.


How does the IEA work in the area of fusion?

The IEA Fusion Power Co-ordinating Committee (FPCC) provides a platform to share results of fusion activities worldwide: the ITER project, the International Atomic Energy Agency, the European Commission (EURATOM), the International Tokamak Physics Activity (ITPA), and the Nuclear Energy Agency.

The FPCC also co-ordinates and oversees the activities of fusion-related multilateral technology initiatives, or Implementing Agreements, that carry out R&D on the physics, technology, materials, safety, environmental and economic aspects, and social acceptance of fusion power. Their work is direct relevance to ITER and the "beyond-ITER" programme (Demo reactor).

What is the international ITER project?

Fusion is arguably one of the major research challenges of the 21st Century. It is an option to provide environmentally benign energy for the future without depleting natural resources for next generations. Therefore, fusion scientists from the European Union, India, China, Japan, Korea, Russia and the United States are proceeding with the construction of a 500 megawatt (thermal power) experimental plant (ITER – the International Thermonuclear Experimental Reactor). Although further research and development work needs to be done on materials and on concept improvements, ITER is expected to be the last major step between today's experiments and a demonstration power plant. For more information on the history of the ITER project, click here.


What is the Nuclear Energy Agency?

The Nuclear Energy Agency (NEA) is a specialised agency within the Organisation for Economic Co-operation and Development (OECD) that assists member countries in maintaining and further developing, through international co-operation, the scientific, technological and legal bases required for the safe, environmentally-friendly and economical use of nuclear energy for peaceful purposes. The NEA and the IEA have a long history of working together. The NEA Director-General is a member of the IEA Governing Board. The NEA regularly contributes with regard to nuclear energy for the IEA country energy reviews and the World Energy Outlook. Key IEA-NEA studies include the Projected Costs of Generating Electricity and Technology Roadmap: Nuclear Energy.