Nuclear energy, also known as atomic energy, is the energy found in the nucleus of an atom. An atom is the smallest known unit of matter that contains the properties of an element, and the nucleus is its dense central core, which is held together with powerful energy. Various types of nuclear reactions release and capture that energy, usually as a method of generating electricity. According to the World Nuclear Association (WNA), about 10 percent of the world's electricity has nuclear origins, and nuclear energy is the second-leading source of low-carbon power. The US Energy Information Agency notes that 20 percent of energy in the United States was derived from nuclear energy in 2019.
Proponents of nuclear energy cite it as a clean, sustainable alternative to using fossil fuels such as coal and natural gas to generate electricity. Fossil fuels release carbon dioxide when they are burned as energy sources, contributing to global climate change. Nuclear energy supporters also emphasize its cost-effectiveness and reliability, features that make it attractive from economic and practical points of view. Opponents contend that nuclear energy is costlier than other renewable alternatives and less environmentally friendly because it creates dangerous radioactive nuclear waste materials. They also cite concerns about the safety and security of nuclear energy, including the risk of potentially devastating accidents or terrorist attacks at nuclear power plants, and the potential for civil nuclear technology to be misapplied in the production of nuclear weapons.
How Nuclear Energy Works
Atomic nuclei are made up of dense subatomic particles known as protons and neutrons. The energy that binds the components of an atomic nucleus ranks among the strongest natural forces known. Releasing and capturing this energy is the end objective of nuclear power generation. Three known techniques can be used to achieve this: fission, fusion, and radioactive decay. Nuclear fission involves bombarding an atomic nucleus with additional neutrons, with the resultant collisions causing atoms to split and release tremendous amounts of energy. Nuclear fusion is the opposite of fission: it is achieved by forcing lighter atomic particles of one element (hydrogen) to collide, which fuses them into heavier particles that form the nuclei of another element (helium) in a process that releases a massive amount of energy. Radioactive decay occurs when an atom's nucleus breaks down, releasing heat energy that can be harvested by a special type of nuclear reactor.
As of 2020, the vast majority of nuclear power is generated by nuclear fission. Nuclear fusion, which occurs naturally in the Sun and other stars, currently remains an experimental process in the power generation industry. Radioactive decay has been used to power spacecraft and research stations in remote areas on Earth but technology remains in developmental stages for electricity generation applications involving power grids.
Nuclear power plants contain specialized reactors, where personnel guide a controlled process to bombard atomic nuclei with neutrons to release energy through fission. Uranium, which has ninety-two protons to rank as the heaviest naturally occurring element, is the preferred raw material for nuclear fission. Its energy density compares very favorably to other sources. For example, it would take three million pounds of coal to generate the same amount of energy released from one pound of uranium by nuclear fission.
When uranium atoms split, they eject neutrons that strike and split adjacent atoms, creating a continuous fission effect known as a chain reaction. Nuclear reactors also contain water and components known as control rods. The energy released by the fission process heats the water to very high temperatures, creating steam that spins turbines. The turbines are part of a power generation system, and the kinetic energy they produce yields electricity that can then be stored and distributed over a power grid. Control rods absorb flyaway neutrons in the reactor core, stabilizing the chain reaction caused by the atomic bombardment process. The fission process also yields highly radioactive nuclear waste, which must be carefully stored and discarded to prevent potentially lethal environmental contamination.
Advantages of Nuclear Energy
Nuclear energy has many appealing features, including cost advantages once operational, high and reliable electricity output, and cleaner emissions profile than fossil fuels. While building and equipping a nuclear power plant require a great deal of upfront investment, these plants produce very inexpensive electricity once they become operational. From a cost perspective, nuclear power compares very favorably to energy sources like natural gas, coal, and other fossil fuels. Its value profile is further enhanced by an outstanding fuel-to-power-output ratio, as a single nuclear power plant using only a small quantity of uranium can produce enough electricity to power a one thousand megawatt station, which is roughly equivalent to the amount of electricity needed by between four hundred thousand and nine hundred thousand US households for one year.
From the perspective of greenhouse gas emissions, nuclear energy is a clean and sustainable power source. Unlike facilities that use materials such as natural gas and coal to create electricity, nuclear plants do not produce any harmful emissions as byproducts of power generation. According to the Nuclear Energy Institute (NEI), nuclear energy accounted for more than 55 percent of the emissions-free electricity created in the United States in 2018, outpacing other sustainable sources like hydropower, wind, and solar energy. Some advocates suggest nuclear power should be utilized on a mass scale as a solution to the ongoing climate change crisis. These factors have led the US Department of Energy (DOE) to describe nuclear power as a clean, sustainable, and practical electricity supply. The DOE also points out that nuclear energy helps safeguard air quality while producing little waste and creating only a modest land use footprint. The DOE considers nuclear power to be highly reliable and is capable of meeting high energy demands.
Nuclear energy may offer several economic benefits as well. According to the NEI, running a single nuclear power plant requires employing five hundred to one thousand workers and creates almost $40 million per year in labor income. The NEI also emphasizes that nuclear power saves large sums of money by reducing carbon emissions. For example, in 2018 the nuclear power facilities in the state of Pennsylvania prevented more than 57 million metric tons of greenhouse gas emissions, saving an estimated $2.6 billion annually in social costs according to an analysis by the US federal government.
Disadvantages of Nuclear Energy
Three of the most common antinuclear energy arguments are the long timeframe and costs of building and decommissioning a nuclear power plant, the radioactive waste fission produces, and its potential to cause devastating accidents. Critics of nuclear energy claim that the nuclear energy industry vastly understates the costs associated with building nuclear power plants, which have escalated over time due to persistent construction delays and cost overruns, which include the costs of ensuring safety and security while the plant is operational and during its decommission. According to critics, taking these large capital expenditures into account makes nuclear power less competitive with renewable energy, which has experienced steep cost decreases in the twenty-first century. One byproduct of the fission process is plutonium, a radioactive chemical that is usually buried deep underground in specially designed repositories. A highly dangerous substance, plutonium emits short-range alpha-particle radiation that can easily be neutralized with the correct procedures but can also cause cancer and other life-threatening reactions in humans exposed to it. Plutonium can also be used as fuel and is a key compound in the production of nuclear weapons, and these properties reinforce objections against allowing some nations to develop nuclear power. Plutonium fuel is dangerously unstable, and nuclear weapons carry such immense destructive force that some politicians and organizations have called for an immediate and total ban on them. Nefarious actors from rogue states or terrorist groups could, in theory, steal plutonium to power so-called dirty bombs, which combine dynamite with radioactive materials, creating additional risks and drawbacks.
High-profile incidents at nuclear facilities in the United States, the former Soviet Union, and Japan underline what is perhaps the most frightening drawback of nuclear energy: the potential for an accident to cause the sudden, uncontrolled release of large amounts of radioactive byproducts into the surrounding environment. Such an incident occurred in 1979 at the nuclear power facility on Three Mile Island in Pennsylvania. A malfunction in a reactor's cooling system caused a partial core meltdown, which led to the release of radioactive vapor. Fortunately, the meltdown was contained without serious environmental contamination, and no injuries, adverse health effects, or fatalities are believed to have occurred.
A far more serious disaster struck the Chernobyl nuclear facility in the Soviet satellite state of Ukraine in 1986, causing fiery explosions and the mass ejection of large radioactive chemical clouds. At least thirty people died of radiation poisoning within weeks of the incident, and adverse health effects caused by the radioactive plume are believed to be responsible for thousands of further fatalities. In 2011 a tsunami disrupted the power supplies and cooling systems in a Japanese nuclear power station, causing multiple core meltdowns. More than one hundred thousand people were evacuated from the surrounding area in a successful bid to avoid fatal exposure to radiation.
While the 1979 and 1986 events can be ascribed to design flaws and operator errors, the 2011 incident caused by a natural disaster reflects that not all nuclear power plant accidents can be avoided. Critics contend that these risks must be accounted for when considering nuclear energy as a viable, large-scale alternative to conventional electricity generation. Opponents of nuclear energy also point out that it is not as environmentally friendly as some claim because uranium mining creates pollution and environmental degradation, which is often overlooked as an aspect of the nuclear power generation process.
Addressing Nuclear Waste
The radioactive waste created by nuclear fission poses serious environmental and human health risks, as it can contaminate soil, water, and agricultural products. Humans exposed to nuclear radiation can experience cell damage and genetic changes known to cause cancer and significantly increase the risk of birth defects. Acute exposure to radioactive waste can also cause radiation poisoning, which can lead to death in a matter of days. Thus, nuclear power plants must carefully manage radioactive waste to limit its potential to cause harm.
According to the Government Accountability Office (GAO), the US commercial nuclear power generation industry is responsible for approximately 89 percent of the 90,000 metric tons of nuclear waste requiring disposal as of March 2020. Nuclear waste is stored at the commercial site where it is generated, and there are more than eighty of these sites in the United States. The GAO expects that figure to rise to about 140,000 metric tons in the decades ahead and notes the absence of a central disposal site in the United States. Nevada's Yucca Mountain has been designated to serve this purpose. Because Yucca Mountain has a projected capacity of only 70,000 metric tons, additional solutions will be required to safely dispose of all the nuclear waste currently available.
Responsibility for regulating and disposing of nuclear waste falls on two federal agencies: the US Department of Energy (DOE) and the Nuclear Regulatory Commission (NRC). These agencies have been seeking a permanent solution to the nation's nuclear waste disposal needs since the early 1980s at a cumulative cost reaching into the billions of dollars. As of March 2020, the Yucca Mountain site still has a license application pending and has not received formal approval. The GAO remains pessimistic about the near-future prospects of solving the issue of nuclear waste disposal in the United States, noting numerous challenges related to costs, transportation, authorizations, and other organizational and administrative obstacles. Political and social opposition to such proposals remain a key stumbling block, along with the associated inconsistencies in policy, funding, and political leadership.