Nuclear power is a way of generating energy by taking advantage of the heat that escapes during the fission process. Heat is generated when certain isotopes are split, which is called fission (as seen in the image to the left). The process begins when enough of the uranium isotope known as U-235 is brought together under the right conditions. Neutrons split off from the U-235, releasing heat and hitting other uranium molecules, knocking more neutrons loose. With enough U-235 a series of fissions can set off a self-sustaining chain reaction, which generates heat.
Nuclear power plants generate energy the same way as other steam-electric power plants. Water is heated with nuclear generated energy until it becomes steam; this steam then turns a turbine and generates electricity. The only difference between steam-electric and nuclear power plants is how the water is heated. Steam-electric power plants use coal, oil, or natural gas to heat the water.
Proponents of nuclear power argue that the U.S. should continue investing in nuclear power. Nuclear power is carbon-free, making less of an environmental impact during production. Power from nuclear energy is produced for less cost per kilowatt than other traditional or renewable energy resources. There is also far less land required to generate energy than is used for solar or wind farms.
Opponents argue that the upfront costs of constructing nuclear power plants are too high, and that it is too difficult to find and train skilled labor. Although nuclear power plants don't produce carbon dioxide, there are environmental impacts during uranium mining, and nuclear reactors require large volumes of water for keeping reactors cool. Additionally, radioactive waste is dangerous and must be handled very carefully.
There are also concerns that the fuel used in nuclear power plants could be stolen and used in weapons. This would be difficult, not only because of the security around these plants, but also because the uranium used in power plants is not enriched enough, and enriching uranium further would be quite difficult. Finally, there has not been any definite link found between nuclear power and disease, but there are concerns that those living near nuclear power plants are at a higher risk of cancer. As with with the production of any other type of energy there are tradeoffs.
History in the United States
Fission, the process central to nuclear power generation, was discovered by Enrico Fermi in 1934 in Rome. By 1942 the first nuclear reactor was built at the University of Chicago, beneath the school's athletic stadium. Using this reactor Fermi and other scientists created the first self-sustaining reactor on December 2, 1942. Following this discovery much of the work done in nuclear energy involved the creation of weapons to be using during World War II under the Manhattan Project. After WWII the U.S. government created the Atomic Energy Commission (AEC). The AEC oversaw the first electricity generated from nuclear power in Idaho on December 20, 1951. Utility companies increased the use of nuclear energy in the 1960s, but demand for nuclear energy declined over the next two decades because of safety, waste, and other environmental concerns. In June of 1970 there were 15 operating electric power nuclear reactors, 54 were being built and there were plans for 32 more. Since 2007 16 license applications have been submitted to build 24 new nuclear reactors; it is expected that six of these may be producing electricity by 2020.
Nuclear energy production in the U.S.
The United States produces 30 percent of the world's nuclear energy, making it the largest producer in the world. In 2012, 19 percent of the electricity generated in the U.S. came from nuclear energy. There are 100 nuclear power reactors at 65 nuclear power plants across the U.S., as seen in the map below. These plants span 31 states and are operated by 30 power companies. These power plants have consistently achieved 90 percent efficiency since 2001.
Uranium and mining
Uranium is a very heavy metal that fuels nuclear reactors. Uranium was discovered in 1789 and is found mostly in rocks, but it can also be recovered from oceans. Uranium is the main source of heat under the earth and fuels convection and continental drift. As with most elements uranium occurs in several slightly different forms known as "isotopes," which differ in the number of uncharged particles (neutrons) in the nucleus. The two most common isotopes of natural uranium found in the earth's crust are: uranium-238 (U-238), which accounts for 99.3% and uranium-235 (U-235), about 0.7%. Uranium ore is mined underground, then ground and treated with acid until the uranium can be accessed. Once the uranium has been extracted is must be enriched. To enrich uranium it must first be turned into a gas (uranium hexafluoride). This gas is then turned into uranium dioxide and formed into pellets. These pellets go into metal tubes and become the core. Uranium is mined in Australia, Kazakhstan, Canada, Russia, South Africa, Namibia, Brazil, Niger, U.S., China, Jordan Uzbekistan, Ukraine and India. Uranium can only be sold to countries that have signed the Nuclear Non-Proliferation Treaty. The graph below shows quarterly uranium production data for the U.S. from 1996 to 2013.
Safety and security
Because of the potential harmful radiation associated with nuclear energy, there are safety and security concerns associated with its production. Nuclear reactors are built to keep fuel cool to prevent meltdowns, control reactivity and contain radioactive substances. However, poor design or construction, human error, insufficient monitoring and failure to act quickly can lead to radiation leaks. One particular scenario of concern is that if the reactor is not properly cooled it can lead to a meltdown, which could create a major public hazard and result in fatalities. According to the World Nuclear Association in the equivalent of 14,500 cumulative reactors years, there have been only three incidents. These incidents include Three Mile Island, Chernobyl and Fukushima.
- On March 28, 1979 there was a meltdown at a nuclear power plant at Three Mile Island in Pennsylvania. It was feared that the meltdown would release harmful radiation, however, widespread radiation contamination never occurred. This event forced the NRC to emphasize how to limit human error in the face of small mechanical failures.
- In Chernobyl, Ukraine in 1986 a steam explosion destroyed a nuclear reactor, killing 56 people. There were also severe human health and environmental impacts that persist to this day. Proponents of nuclear energy argue that this incident should be considered an outlier because of poor reactor design and lack of proper oversight and because this incident occurred under the governance of the former Soviet Union.
- Following a large tsunami in Fukushima, Japan in 2011, three nuclear reactors melted down due to a loss of cooling. Proponents of nuclear energy argue that the Fukushima disaster demonstrate that a nuclear reactor could melt down without causing serious public harm and fatalities, a departure from previous understanding of the effects of a meltdown.
There have been several accidents involving experimental reactors across the world, but aside from Chernobyl no nuclear plant workers or members of the public have died from commercial nuclear accidents.
Radioactive waste is the by-product of using radioactive materials, such as uranium, to generate energy. The NRC classifies two main types of radioactive waste generated from nuclear power plants.
Low-level waste items have been contaminated by radiation during the power generating process. These items include protective clothing, filters, tools, rags, etc. There are four low-level waste disposal facilities in the United States, as seen in the map to the right.
High-level waste is spent or irradiated nuclear fuel. This waste comes in two forms, spent nuclear fuel and waste materials from spent fuel reprocessing. Spent fuel comes when the self-sustaining chains that generate heat for electricity production begin to slow, making electricity generation inefficient. Even though the process has slowed, the U-235 is still a hot, extremely radioactive material that must be disposed of properly to ensure no harm to human health or the environmental. The second type, waste materials, are "reprocessing extracts isotopes" that can be used again to fuel reactors. This use of reprocessed isotopes doesn't currently occur in the United States. High-level waste must be stored for hundreds of thousands of years before the radioactivity levels decrease enough to become harmless.
Regulatory agencies in the U.S.
- The Atomic Energy Commission (AEC) was established by Congress under the Atomic Energy Act in 1946 to manage the use of nuclear energy in military and civilian operations. Then in 1954 Congress passed a new version of the Atomic Energy Act making it possible for the development of nuclear power for commercial uses. Under this new law the AEC was responsible for overseeing programs that protected public health and safety, while allowing a new industry to develop without burdensome regulation. Critics felt there was too little regulation and eventually the AEC was reorganized into the Nuclear Regulatory Commission.
- The Nuclear Regulatory Commission (NRC) was created in 1974 with the Energy Reorganization Act. The NRC took over the operations of the AEC, and is the main body regulating nuclear energy production today. The NRC oversees radiation protection, reactor safety and licensing and the oversight of spent nuclear fuels.
- The Office of Nuclear Material Safety and Safeguards (NMSS) implements NRC regulations and policies regarding spent fuel disposal.
- The Office of Federal and State Materials and Environmental Management Programs (FSME) develops guidelines for compliance with environmental protections and oversees the decommissioning of uranium mining sites and other contaminated areas.
Ballot initiatives in the U.S.
- See also: ballot initiatives in the United States
Support for nuclear energy has fluctuated during its history in the U.S. because of the risks associated with its production. Some members of the public have been very supportive of this method of energy production because it has a small carbon footprint, while others have tried to ban the practice, sometimes through ballot measures. These measures cover many issues ranging from requiring local approval before the detonation of nuclear devises, to the regulation of and banning of nuclear waste facilities and to power plant regulation. As of March 2014, the states that have had ballot measures regarding nuclear energy include: Arizona, California, Colorado, Idaho, Maine, Massachusetts, Missouri, New Jersey, North Dakota, Ohio, Oregon, South Dakota, Utah, Washington and Wisconsin. The most recent ballot measure to appear on the ballot was in Washington in 2004, creating new regulations for radioactive waste. There have been several proposed ballot measures that have not made it on the ballot since 2008.
- Department of Energy, "The History of Nuclear Energy," accessed March 13, 2014
- The Discovery Channel, "10 Pros and Cons of Nuclear Power," March 14, 2014
- Office of Assistant General Manager for Reactors, "Nuclear Reactors Built, Being Built, or Planned in the United States as of June 30, 1970," accessed March 14, 2014
- World Nuclear Association, "Nuclear Power in the USA," February 20, 2014, accessed March 13, 2014
- U.S. Energy Information Administration, "Energy in Brief," December 14, 2012, accessed March 13, 2014
- World Nuclear Association, "What is Uranium? How Does it Work?," December 2012, accessed March 17, 2014
- U.S. Energy Information Administration, "Energy in Brief," December 14, 2012, accessed March 13, 2014
- "World Nuclear Association," "Safety of Nuclear Power Reactors," October 2013, accessed March 14, 2014
- Nuclear Regulatory Commission, "History," accessed March 13, 2014
- Nuclear Regulatory Commission, "Locations of Low-Level Waste Disposal Facilities," March 25, 2013, accessed March 13, 2014
- Nuclear Regulatory Commission, "Radioactive Waste," January 13, 2014, accessed March 13, 2014
- Nuclear Regulatory Commission, "High-Level Waste," April 6, 2012, accessed March 13, 2014
- National Energy Commission, "Atomic Energy Commission," December 11, 2013, accessed March 14, 2014
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