Nuclear energy is energy in the nucleus, or core, of an atom. Atoms are tiny particles that make up every object in the universe. Bonds that hold atoms together contain large amounts of energy that is released in the form of heat in two ways: nuclear fusion and nuclear fission.
How Nuclear Energy is Formed
In nuclear fusion, atoms release energy as they combine or fuse together to form a larger atom. For instance, this is how the sun produces energy. Fusion creates energy with less radioactive material, but it is harder to control the reaction.
Nuclear fission is the process of splitting apart uranium atoms in a controlled manner that creates energy. If the chain reaction of splitting the atoms is not controlled very carefully, an atomic explosion could occur (although the conditions have to be perfect in order for an atomic bomb to occur, and these conditions are not present in nuclear reactors). The fission process gives off heat energy, which is used to boil water in a power plant’s reactor core. The steam created with this water is used to turn a turbine, generating electricity.
Physics and chemistry played an important role in the discovery of nuclear fission, and today physicists and chemists work together with engineers to make nuclear power possible. Expertise in physics and chemistry are critical to controlling the chain reaction of splitting atoms.
Where Does Uranium Come From?
Uranium, which is used for nuclear reactions, is a mineral found in the Earth’s crust in spots around the globe. Major producers include:
- United States
- South Africa
In uranium’s early days as an energy source, the mineral was usually extracted in open pit mines on the surface of the Earth. This practice continued until the 1960s, when most mining moved underground.
Today, most US and Kazakhstan uranium mines use a process called in-situ leaching (ISL), which dissolves the mineral while it’s still in the ground and then pumping it to the surface. ISL mines last one to three years on average, with 60-80% of the available ore recovered.
History of Nuclear Energy
Nuclear energy is a relatively new energy source. It was discovered in the 20th century, unlike fossil fuels, which have been used for millions of years.
1900 – Physicists discover the atom contains large quantities of energy.
1904 – British physicist Ernest Rutherford earns the nickname “the father of nuclear science” because of his contribution to the theory of atomic structure.
1905 – Albert Einstein develops his theory of the relationship between mass and energy. The mathematical formula is E=mc2, or “energy equals mass times the speed of light squared.” This theory was proven almost 35 years later.
Albert Einstein publishes his paper on the photoelectric effect, along with a paper on his theory of relativity.
1934 – Physicist Enrico Fermi conducts experiments in Rome that show neutrons could split into many kinds of atoms. When his team bombarded uranium with neutrons, the surprising results indicated that the elements were much lighter than uranium.
1938 – German chemists Otto Hahn and Fritz Strassmann fire into uranium neutrons from a source containing the elements radium and beryllium. They were surprised to find lighter elements, such as barium, in the leftover materials.
Hahn and Strassman contact Austrian physicists Lise Meitner and Meitner’s nephew, Otto Robert Frisch. Meitner and Frisch thought the barium and other light elements in the leftover material resulted from the uranium splitting — or fission. They added the atomic masses of the fission products and saw that they did not total the uranium’s mass. Meitner used Einstein’s theory to show the lost mass changed to energy. This proved fission occurred and confirmed Einstein’s work.
1942 – Enrico Fermi and Hungarian physicist Leo Szilard, who had both emigrated to the US, create the first man-made reactor, known as Chicago Pile-1. In addition to uranium and graphite, it contained control rods made of cadmium, a metallic element that absorbs neutrons. When the rods were in the pile, there were fewer neutrons to fission uranium atoms. This slowed the chain reaction. When the rods were pulled out, more neutrons were available to split atoms. The chain reaction sped up.
Chicago Pile-1 is demonstrated on Dec. 2. Control rods were withdrawn a few inches at a time during several hours until finally the nuclear reaction became self-sustaining. Scientific theory became a technological reality.
Most early atomic research focused on developing an effective weapon for use in World War II under the code name the Manhattan Project. However, some scientists worked on making breeder reactors, which would produce fissionable material in the chain reaction.
1951 – Electricity is generated for the first time by a nuclear reactor on Dec. 20 at the EBR-I experimental station near Arco, Idaho. About 100kW was initially produced. It became the world’s first electricity-generating nuclear power plant when it produced sufficient electricity to illuminate four 200-watt light bulbs. It subsequently generated sufficient electricity to power its building, and continued to be used for experimental purposes until it was decommissioned in 1964.
1953 – US President Dwight Eisenhower’s speech, “Atoms for Peace,” calls for greater international cooperation in the development of atomic energy for peaceful purposes.
1954 – The USSR’s Obninsk Nuclear Power Plant became the world’s first nuclear power plant to generate electricity for a power grid, and produced around 5 megawatts of electric power.
1955 – The United Nations’ “First Geneva Conference”, then the world’s largest gathering of scientists and engineers, met to explore nuclear technology.
1956 – The world’s first commercial nuclear power station, Calder Hall in Sellafield, England, opened with an initial capacity of 50 MW (later 200 MW).
1957 – EURATOM, the European Atomic Energy Community, is launched alongside the European Economic Community, which is now known as the European Union.
The International Atomic Energy Agency (IAEA) is launched.
The world’s first large-scale nuclear power plant begins operation in Shippingport, Pennsylvania. The plant reaches full power three weeks later and supplies electricity to the Pittsburgh area in the U.S.
1958 – Construction begins on the world’s first nuclear-powered merchant ship, the N.S. Savannah, in Camden, New Jersey. The ship launched July 21, 1959.
1970 – The United States, United Kingdom, Soviet Union, and 45 other nations ratify the Treaty for Non-Proliferation of Nuclear Weapons.
1974 – The first 1,000-megawatt-electric nuclear power plant goes into service: Commonwealth Edison’s Zion 1 Plant.
1991 – At the end of 1991, 32 countries had nuclear power plants in commercial operation or under construction, indicating worldwide commitment to nuclear power technology.
Today – Nuclear power plants emit little more carbon dioxide per megawatt than wind and geothermal power plants. Regions around the world are expanding their uranium production, including plans for 10new nuclear facilities in Iran, plans or proposals for new nuclear reactors in 12 European countries and 19 planned or proposed nuclear power reactors in India.
Uses for Nuclear Energy
Nuclear power is primarily used for ship propulsion and electricity generation. About 15% of the world’s energy comes from nuclear power. Some countries rely on nuclear energy for the majority of their electric power.
It also plays an important role in medicine, industry, science, food preservation and agriculture:
- Physicians use radioisotopes to identify and investigate the causes of disease. They also use them to enhance traditional medical treatments.
- Radioisotopes are also used by industry to measure microscopic thicknesses, detect irregularities in metal casings and to test welds.
- Archaeologists use nuclear techniques to date prehistoric objects and to locate structural defects in statues and buildings.
- Nuclear irradiation of food (treating food with ionizing radiation that kills bacteria and parasites) causes less vitamin loss than canning, freezing or drying in food preservation, and it can cut down on food borne illnesses
Demand for Nuclear Energy
Nuclear power is an important source of energy in many countries. In 2008, 16 countries got more than 25% of their electricity from nuclear plants. Lithuania, France, Slovakia and Belgium rely on nuclear power for more than 50% of their total electric power. According to 2008 data from the Nuclear Energy Agency, the United States relies on nuclear power for nearly 20% of its electricity supply, and the United Kingdom gets nearly 14% of its electricity from nuclear sources.
Higher oil and gas prices make alternatives such as nuclear power more attractive and are expected to lead to growth in nuclear generating capacity worldwide. Improvements in reactor design enhance safety, increase efficiency and reduce costs, making nuclear generation an economically attractive source of energy.
France has long been Europe’s leader in nuclear power, with 59 working nuclear reactors and 77% of the country’s electricity coming from nuclear power.
Environmental concerns about the disposal of spent nuclear fuel persist, and countries are addressing those concerns in different ways. The US is developing a disposal facility on government property, but this solution is itself controversial.
Nuclear Energy: Safety and the Environment
The expansion of nuclear power as an energy source is at least partially restricted by the public’s perception of its safety and its impact on the environment. However, the World Nuclear Association asserts that the use of nuclear energy for electricity generation is safer than the use of fossil fuels like coal and petroleum, thanks to the industry’s dedication to safety in plant design and operations.
But concerns remain that radioactive waste might be accidentally released into the environment, that nuclear power could be used in warfare and that long-term storage of radioactive materials poses an environmental threat.
In-situ leach uranium mines cause little surface disturbance, and once the mine is capped, rehabilitation is fairly simple (the wells are sealed, processing equipment removed and the land can once again be used as it was before the mining). The key environmental concern of ISL mining is keeping the solution used to flush the uranium to the surface from contaminating nearby water supplies.
Storage and Disposal of Radioactive Waste
Ever since nuclear power was first developed, scientists have been searching for the safest, most efficient way to deal with the resulting radioactive waste materials. Disposal options that have been researched include burying waste under the ocean floor, blasting it into space and storing it in polar ice. But these methods—and many more—have been deemed unsafe.
The most commonly used method of disposal is storing nuclear waste deep underground in stable geological locations. According to the World Nuclear Association, these geological storage sites include natural and man-made barriers to keep waste from reaching the surface, even when earthquakes occur. Nuclear power produces far less waste than other energy sources.
What about Nuclear Proliferation?
International safeguards to prevent nuclear proliferation have been in place for many years. The Nuclear Non-Proliferation Treaty, which went into effect in 1970, regulates the security and export of nuclear materials, enforces nuclear test bans and works to prevent civil uranium (used to generate electricity) from being put to military use. More than 180 countries have signed the treaty, but others have opted not to sign (India, Israel, Pakistan) or have been found in violation of the treaty (Iran, Libya).
The United Nations’ International Atomic Energy Agency also conducts investigations of civil nuclear plants worldwide to ensure that nuclear materials are not being diverted to military use.