Nuclear power

Nuclear power is the use of nuclear reactions to produce electricity. Today, most nuclear power comes from splitting atoms of uranium and plutonium in special plants called nuclear power plants. These plants generate a lot of energy without producing smoke or gases that hurt our planet.

The first nuclear power plant began operating in the 1950s. Over time, many countries built these plants to help meet their energy needs. However, some serious events, like the Three Mile Island accident in the United States and the Chernobyl disaster in the Soviet Union, led to more rules and careful oversight.

Even with these concerns, nuclear power is considered a clean energy source because it does not release greenhouse gases that warm the Earth. It also helps save lives by reducing air pollution that would come from burning coal and other fuels. Today, nuclear power provides about 9% of the world's electricity and continues to grow, especially in parts of Asia.

History

Main articles: History of nuclear power and Timeline of nuclear power

Origins

The process of nuclear fission was discovered in 1938 after many years of studying radioactivity and learning more about the parts of atoms. Scientists found that tiny particles called neutrons, released when a nucleus splits, could cause nearby nuclei to split too, creating a continuing chain reaction. This was proven in experiments in 1939.

Soon after, scientists in many countries asked their governments for support to study nuclear fission, especially because World War II was beginning. In the United States, this research led to the first human-made nuclear reactor, called the Chicago Pile-1, built under a stadium at the University of Chicago. It began working on December 2, 1942, as part of the Manhattan Project, the effort by the Allied countries to build atomic bombs. This led to building larger reactors to make weapons-grade plutonium for the first nuclear weapons. The United States tested the first nuclear weapon in July 1945, and the atomic bombings of Hiroshima and Nagasaki happened one month later.

Even though the first nuclear devices were for military use, there was hope in the 1940s and 1950s that nuclear power could provide lots of cheap energy. In 1951, electricity was made for the first time by a nuclear reactor at the EBR-I station near Arco, Idaho, making about 100 kW. In 1953, American President Dwight Eisenhower gave a speech called "Atoms for Peace" at the United Nations, saying that nuclear power should be used for peaceful purposes. This led to the Atomic Energy Act of 1954, which made it easier for private companies to develop nuclear technology.

First power generation

The first group to make practical nuclear power was the U.S. Navy, building the S1W reactor to power submarines and aircraft carriers. The first nuclear-powered submarine, USS Nautilus, went to sea in January 1954. The S1W reactor was a pressurized water reactor, chosen because it was simple, small, and easy to operate—ideal for submarines. This design later became popular for making electricity too.

On June 27, 1954, the Obninsk Nuclear Power Plant in the USSR became the world’s first nuclear power plant to supply electricity to a city, making about 5 megawatts. The world’s first commercial nuclear power station, Calder Hall in England, was connected to the power grid on August 27, 1956. Like some other early reactors, it made electricity and plutonium-239 for Britain’s nuclear weapons program.

Expansion and first opposition

The amount of nuclear power around the world grew quickly at first, going from less than 1 gigawatt (GW) in 1960 to 100 GW by the late 1970s. But during the 1970s and 1980s, rising costs, longer building times, and falling prices for oil and gas made new nuclear plants less attractive. In the 1980s in the U.S. and 1990s in Europe, changes in electricity rules made it harder to invest in new nuclear plants, which are expensive to build but cheap to run, compared to natural gas plants, which were faster to build and had cheap fuel.

The 1973 oil crisis made countries like France and Japan, which used lots of oil for power, decide to invest in nuclear power. France built 25 nuclear plants over 15 years, and by 2019, nuclear power made 71% of France’s electricity—the highest share in the world.

Some people began to worry about nuclear power in the early 1960s in the United States. By the late 1960s, scientists were speaking out about concerns including nuclear accidents, the spread of nuclear weapons, and how to handle radioactive waste. In the early 1970s, large protests happened in Wyhl, Germany, against a new nuclear plant, and the project was cancelled in 1975. This success led to more opposition to nuclear power across Europe and North America.

By the mid-1970s, opposition to nuclear power became stronger, and it turned into major public protests in some countries. This led to longer processes for getting permission to build new plants, more rules, and more safety equipment, which made new nuclear plants even more expensive. In the United States, over 120 reactor proposals were ultimately cancelled, and building new reactors slowed down a lot. The 1979 accident at Three Mile Island played a big role in reducing new plant constructions in many countries.

Chernobyl and renaissance

During the 1980s, on average a new nuclear reactor started up every 17 days. By the end of the decade, the world had 300 GW of nuclear power. Since the late 1980s, adding new nuclear power slowed down, and by 2005, the world had 365 GW.

The 1986 Chernobyl disaster in the USSR, involving an RBMK reactor, changed how nuclear power developed and led to a stronger focus on safety rules around the world. It was the worst nuclear disaster in history, both because of the number of people affected and the cost of cleaning up, which was estimated at US$68 billion in 2019. The disaster led to the creation of the World Association of Nuclear Operators (WANO) to help improve safety in nuclear facilities. The Chernobyl disaster also caused many countries to stop building new nuclear plants. Italy voted against nuclear power in 1987 and stopped using it completely by 1990.

In the early 2000s, there was hope for a “nuclear renaissance” because of worries about carbon dioxide emissions. During this time, newer generation III reactors, such as the EPR, began to be built.

Fukushima accident

Plans for a nuclear renaissance were delayed by another nuclear accident. In 2011, the Fukushima Daiichi nuclear accident happened after the Tōhoku earthquake and tsunami, one of the largest earthquakes ever recorded. The Fukushima Daiichi Nuclear Power Plant had three reactors that melted because the cooling system stopped working when the power went out. This became the worst civilian nuclear accident since Chernobyl in 1986.

The accident led many countries to look again at nuclear safety and plans for nuclear power. Germany decided to close all its nuclear reactors by 2022, and many other countries looked again at their nuclear programs. After the disaster, Japan shut down all its nuclear reactors, some forever, and in 2015 began carefully restarting some of the others.

In 2022, Japan’s government said it would reopen 10 more nuclear plants since the 2011 accident. The leader of Japan also wants to build new, safer nuclear plants to help the country save money on fuel and reduce greenhouse gas emissions. Japan hopes to become a big exporter of nuclear energy and technology to help other developing countries.

Current prospects

By 2015, international groups saw nuclear energy as important for helping fight climate change because it doesn’t produce carbon dioxide. In 2016, a group in the United States guessed that world nuclear power generation would grow from 2,344 terawatt hours (TWh) in 2012 to 4,500 TWh in 2040. Most of this growth was expected in Asia. In 2018, over 150 new nuclear reactors were planned, with 50 being built. In January 2019, China had 45 reactors operating, 13 being built, and plans for 43 more, making it the largest maker of nuclear electricity.

In October 2021, Japan’s government approved a new plan for electricity to 2030, which includes restarting ten more reactors. In July 2022, Japan’s leader said the country should think about building advanced reactors and letting some reactors keep operating longer than 60 years.

In 2022, with oil and gas prices rising, while Germany was restarting its coal plants because it lost Russian gas, many other countries made big plans to bring back older nuclear plants and build new ones. The leader of France said he wants to build six new reactors to help France reach carbon neutrality by 2050. In the United States, the Department of Energy is working with companies TerraPower and X-energy to build two new kinds of nuclear reactors by 2027, with more plans for the future.

Power plants

See also: List of commercial nuclear reactors and List of nuclear power stations

Nuclear power plants make electricity by using heat from splitting atoms. Inside a nuclear power plant, there is a special machine called a reactor where the splitting happens. This heat is used to make steam, which turns a turbine. The turbine then spins a generator, which makes electricity.

When a tiny particle called a neutron hits the nucleus of certain atoms, like uranium or plutonium, it can split the nucleus apart. This splitting gives off energy and more neutrons, which can split more nuclei. This is called a chain reaction. Special parts called control rods help keep the reaction at a safe level by soaking up extra neutrons.

Fuel cycle

Main articles: Nuclear fuel cycle and Integrated Nuclear Fuel Cycle Information System

The nuclear fuel cycle starts with uranium mining. The uranium ore is turned into a compact ore concentrate, called yellowcake (U₃O₈), to make it easier to transport. Most reactors need uranium-235, a special type of isotope of uranium. Natural uranium has only a small amount of uranium-235 (about 0.7%). Some reactors can use natural uranium directly, but most need the amount of uranium-235 to be increased through a process called uranium enrichment. After enrichment, the uranium is turned into uranium oxide (UO₂), a ceramic, and then made into small fuel pellets that are stacked into fuel rods for use in reactors.

When fuel has been used in a reactor for a while, it has less of the useful material and more waste products, so it is moved to a special pool where it cools down. After some time, it can be moved to dry storage containers.

Uranium resources

Main articles: Uranium market, Uranium mining, and Energy development § Nuclear

Uranium is a common element in the Earth's crust, found in rocks, dirt, and ocean water. It is usually only mined where it is found in higher amounts. As of 2011, known uranium resources could last for about 70 to 100 years at current use rates.

Most reactors today use only a small part of natural uranium, called uranium-235. New technologies could use much more of the uranium we have, including waste from older reactors. Some ways to get more uranium include using seawater, which contains small amounts of uranium.

Waste

Main article: Nuclear waste

Nuclear power plants create radioactive waste, which can be low-level or high-level. Low-level waste has low radioactivity and includes things like gloves or tools. High-level waste is mostly used fuel from reactors, which is very radioactive and needs careful handling.

High-level waste

Main articles: High-level waste and Spent nuclear fuel

The most important waste from reactors is spent nuclear fuel, which is very radioactive. It is first stored in pools to cool down, and later moved to dry storage containers. Over time, the radioactivity decreases a lot. After many years, it becomes less radioactive than the original uranium ore.

Low-level waste

Main article: Low-level waste

The nuclear industry also creates low-level waste, such as gloves or tools that have small amounts of radioactivity. This waste can often be disposed of like normal trash after the radioactivity levels drop.

Waste relative to other types

See also: Radioactive waste § Naturally occurring radioactive material

In countries with nuclear power, radioactive waste makes up a small part of all industrial waste. Nuclear power actually creates less waste than coal power plants, which release radioactive materials from coal into the air.

Nuclear waste takes up very little space compared to the amount of energy it produces. For example, the waste from a lifetime of energy use for one person would fit in a small container.

Waste disposal

See also: List of radioactive waste treatment technologies

Used fuel is first stored in pools and then often moved to dry storage containers at the power plant. Some places are building deep underground storage sites for long-term disposal.

There are no large underground waste storage sites in use yet, but Finland is building one called the Onkalo spent nuclear fuel repository.

Reprocessing

Main article: Nuclear reprocessing

See also: Plutonium Management and Disposition Agreement

Most reactors use fuel only once because uranium is cheap. However, some places recycle parts of the used fuel to make new fuel. This can reduce waste and make more energy from the same uranium. Recycling used fuel is done in several countries, but not in the United States.

Breeding

Breeding turns non-useful material into fuel that can be used in special reactors called breeder reactors. These reactors can use almost all of the uranium we have, including waste from older reactors. Some countries are building these types of reactors to make better use of our uranium resources.

Another way to get more fuel is by using thorium, which is more common than uranium. Some countries, like India, are working on using thorium as fuel.

Decommissioning

Main article: Nuclear decommissioning

Nuclear decommissioning is the process of taking apart a nuclear facility so that it no longer needs special safety measures for radiation. This process can be difficult and costly because of the radioactive materials involved. The costs for decommissioning are usually saved up during the time the facility is in use, in a special fund.

Production

Nuclear power is a way to make electricity by using special reactions in tiny parts of atoms. In 2023, nuclear power made about 9% of all the world's electricity. It was the second most used clean energy source after hydroelectric power.

As of November 2024, there are 415 nuclear reactors working around the world, with more being built. The United States makes the most nuclear electricity, while France uses nuclear power for most of its electricity needs. Some ships also use nuclear power to move around. Scientists are studying new ways to use nuclear heat, like making clean water from sea water.

Economics

Main articles: Economics of nuclear power plants, List of companies in the nuclear sector, and cost of electricity by source

Building new nuclear power plants can be very expensive. This makes it important to think about how long it takes to build them and how money is used during the process. The cost of electricity from nuclear power depends a lot on these factors.

Studies show that nuclear power can be one of the cheaper ways to make electricity that is always available. Other energy sources like wind and solar can be cheaper, but they don’t always work when we need them. Adding costs for things like carbon taxes can make nuclear power even more competitive. Some countries, like India and South Korea, have managed to lower the costs of building nuclear plants. New smaller designs might also help reduce these costs.

Use in space

Nuclear power is used in space mainly through small devices called radioisotope thermoelectric generators. These use natural changes in special materials to create energy. They are used to power space missions and experiments when sunlight is not enough, like on the Voyager 2 probe. A few space vehicles have also used small nuclear reactors for power. Both splitting atoms and combining atoms show promise for helping spacecraft travel faster with less heavy fuel.

Safety

See also: Nuclear safety and security and Nuclear reactor safety system

Nuclear power plants have special safety features because they use materials that can be very powerful and dangerous. These materials can stay hot even after the plant stops working, so special systems are needed to keep them cool. If these systems stop, the materials can become too hot and spread dangerous substances.

Modern nuclear plants are built with safety systems that naturally stop the reaction if things get too hot. There are also special tools that workers can use to stop the reaction if needed. Even if some systems fail, the plant has strong walls to keep dangerous materials from spreading out.

See also: Energy accidents, Nuclear and radiation accidents and incidents, and Lists of nuclear disasters and radioactive incidents

Some serious accidents have happened at nuclear power plants. These accidents are ranked on a scale to show how serious they are. The worst accidents happen very rarely and can affect many people and places.

Accidents can cause problems for people who have to leave their homes and can make them feel very worried and stressed. It is important to learn from these accidents to make nuclear plants safer.

Main articles: Vulnerability of nuclear plants to attack, Nuclear terrorism, and Nuclear safety in the United States

Proliferation

Further information: Nuclear proliferation

See also: Plutonium Management and Disposition Agreement

Nuclear proliferation means the spread of nuclear weapons and materials to countries that do not already have them. This is a concern because the same technology used to make electricity can also be used to make weapons.

Some countries have tried to share nuclear fuel to help others get energy while making sure they do not build weapons. One example is Iran’s nuclear program, which has raised worries. Many countries work together to prevent the wrong use of nuclear technology. Programs like the Megatons to Megawatts Program have helped turn materials that could be used in weapons into fuel for power plants, which has reduced the number of nuclear weapons in the world.

Environmental impact

Main article: Environmental impact of nuclear power

Nuclear power is a clean energy source that does not produce much carbon dioxide, a gas that harms the environment. It also does not need a lot of land to operate. However, there are some risks. These include the possibility of accidents, the safe handling of radioactive waste, and the potential misuse of materials for weapons.

Carbon emissions

See also: Life-cycle greenhouse gas emissions of energy sources

Nuclear power is one of the best ways to make electricity without creating harmful gases. In fact, it produces very little carbon dioxide compared to other energy sources like coal or natural gas. Since 1970, nuclear power has helped stop a huge amount of carbon dioxide from being released into the air.

Radiation

The natural radiation we receive from the Earth is about 2.4 millisieverts each year. Nuclear power plants add a very tiny amount to this, much less than the radiation from coal power plants. The accident at Chernobyl caused higher radiation levels for people nearby, but the rest of the world experienced only a very small increase that is still decreasing over time.

Debate

See also: Nuclear energy policy, Pro-nuclear movement, and Anti-nuclear movement

People have different opinions about using nuclear power to make electricity. Some think it is a good idea because it does not create as much pollution as burning coal or oil. They say it helps reduce the amount of harmful gases put into the air.

Others worry about safety and cost. They think nuclear power can be dangerous and expensive. They also worry about how to safely store the waste it creates.

Comparison with renewable energy

See also: Renewable energy debate

To help protect our planet, we need to use less coal and oil. Some people think nuclear power can help with this, while others think we should use more natural sources like wind and sun.

Nuclear power creates less waste than some renewable sources, but the waste it does create is very dangerous and must be stored safely for a very long time. Nuclear power plants are also more complicated to shut down than plants using wind or solar power.

Nuclear power could be built up quickly to replace coal and oil, but it would still need careful planning and support from governments and communities.

Research

Advanced fission reactor designs

Main article: Generation IV reactor

Today's nuclear power plants are mostly second or third generation systems, with many first-generation plants already retired. Scientists are researching advanced generation IV reactors through the Generation IV International Forum (GIF). These new designs aim to improve cost, safety, and waste handling, and they could start being built commercially after 2030.

Hybrid fusion-fission

Main article: Nuclear fusion–fission hybrid

Hybrid nuclear power mixes fusion and fission processes to create energy. This idea started in the 1950s and got more attention around 2009 because pure fusion was taking longer to develop. Once a fusion power plant works well, it could help use up old nuclear waste and make it much less harmful.

Fusion

Main articles: Nuclear fusion and Fusion power

Nuclear fusion could be safer and create less radioactive waste than today’s nuclear power. It looks possible, but it’s very hard to do, and we haven’t built a fusion power plant yet. Scientists have been studying fusion since the 1950s, but it probably won’t be ready for everyday use before 2050.

One big project is ITER, a large machine called a tokamak being built in France. ITER is supposed to show that fusion can work well enough to make power. Building started in 2007, but it has faced delays and might not start until 2034. After that, there’s a plan for a commercial fusion power plant called DEMO.

The U.S. government gave $46 million in 2023 to eight companies to speed up fusion research, hoping to build a test plant within ten years.