Q. How much electricity is provided by nuclear power?
Q. What are the advantages of nuclear power?
Q. What is fission?
Q. Do nuclear plants affect the environment?
Q. Can a nuclear reactor explode?
Q. What are nuclear wastes?
Q. How much nuclear waste is there?
Q. How can nuclear wastes be disposed of safely?
Q. How much electricity is provided by nuclear power?
A. Nuclear power plays a significant part in meeting today’s electricity needs and will continue to serve as an important source of electric energy. In 1998, 19 percent of U.S. electricity production was generated by nuclear power plants, making nuclear power plants the second largest source of electricity in the nation.
Q. What are the advantages of nuclear power?
A. Nuclear power offers numerous advantages as a source of electric energy:
Nuclear power plants have a record of safety excellence that dates back to 1957 when the first commercial nuclear plant began operating; using proven technology, nuclear plants have operated reliably to meet electricity needs; uranium, the fuel for nuclear plants, is a relatively inexpensive fuel that is abundant throughout the world; and nuclear power produces no air pollutants.
Because of these and other advantages, utilities have relied on nuclear power to meet an increasingly large portion of their customers’ electricity needs.
Q. What is fission?
A. To understand the basics of nuclear power production, it is necessary to understand the characteristics of atoms.
Atoms, the fundamental components of all matter, are composed of three primary particles: protons, neutrons, and electrons. Protons and neutrons comprise the center, or nucleus. The protons and neutrons are held together by a powerful force called nuclear energy.
The nuclear energy can be overcome in large atoms, causing them to split apart or "fission." Uranium-235 is a large atom with 92 protons and 143 neutrons in its nucleus. When a neutron strikes a uranium-235 atom, its nucleus becomes unstable. The atom then splits into two smaller atoms (fission products), releases two or three neutrons, and releases energy in the form of heat. The "free" neutrons released can strike other uranium-235 atoms, causing them to fission, and this process, or chain reaction, will continue as long as there are uranium-235 atoms available.
In a nuclear power plant, the heat produced during the chain reaction is used to boil water to produce steam. The rest of the nuclear power plant's operations are not very different from that of a fossil-fuel plant. Nuclear plants, however, produce much greater amounts of energy for the amount of material consumed. For example, just one pound of nuclear fuel produces more energy than 240 tons of coal, 830 barrels of oil, or five million cubic feet of natural gas.
Q. Do nuclear plants affect the environment?
A. All methods for producing electricity affect the environment to some degree. Nuclear power has a minimal environmental impact. Since nuclear plants do not burn fuel, they emit none of the combustion byproducts produced by fossil-fueled plants. Nuclear plants do emit very small amounts of radiation, just as fossil-fueled plants do, but the levels pose no danger to the environment.
The environmental impact of mining and transporting nuclear fuel is considerably less than for other fuels. Since uranium is capable of producing larger amounts of energy than similar amounts of other fuels, smaller amounts can be mined and transported to produce the same amount of electricity.
Q. Can a nuclear reactor explode?
A. It is physically impossible for a commercial nuclear reactor to explode like an atomic bomb, whether by accident, sabotage, or any other cause. The composition of nuclear fuel used to generate electricity is quite different from the materials used in a bomb.
The difference between commercial nuclear reactors and atomic bombs can be illustrated by the difference between grain and bread. Explosions sometimes occur in grain silos when a spark ignites an area full of fine grain dust and the grain’s chemical energy is released suddenly. Once the grain has been made into bread, that same chemical energy can be released slowly by the human digestive process. However, nothing can be done to this new chemical and physical arrangement of grain - in the form of bread - to make it explode. Similarly, nuclear materials must be brought together almost instantaneously for an explosion to occur, and commercial nuclear reactors only can release energy slowly.
Q. What are nuclear wastes?
A. When nuclear fuel is first placed in a commercial reactor, it consists of uranium oxide. After the fuel has been used for three or four years, it consists of about 96 percent uranium oxide and about 3 percent new elements - including iodine, strontium, carbon, xenon, cesium, silver, and palladium. These are nuclear wastes.
Spent nuclear fuel is termed "high-level waste," since it is considerably more radioactive than new fuel. A person can handle new fuel pellets of uranium oxide without danger. In contrast, spent fuel is dangerously radioactive, although much of the radioactivity dissipates quickly - some 98 percent within six months. Forty to 50 years after spent fuel is removed from the reactor, its radioactivity has decreased by a factor of 100. A very small percentage of nuclear wastes remain radioactive for thousands of years.
In addition to high-level waste, another category of nuclear waste associated with nuclear power is called "low-level waste." Low-level waste is generally anything that becomes contaminated with radioactive materials during its use. Such items include rags, papers, cleaning materials, protective clothing, tools, and contaminated liquids.
Uranium mine and mill tailings - the residue, sludges, and sands from uranium mining and milling operations - also are considered nuclear wastes because they contain very small concentrations of natural radioactive elements.
Q. How much nuclear waste is there?
A.The commercial nuclear power industry has accumulated about 17,000 tons of spent nuclear fuel. Buy the year 2000, nuclear plants will have produced a total of about 40,000 tons of spent fuel.
The military nuclear program has accumulated about 100 times more nuclear waste than commercial nuclear plants. In addition, about 180 million tons of extremely low-level wastes have been generated by uranium and milling and disposed of at mine sites.
Q. How can nuclear wastes be disposed of safely?
A.Nuclear wastes can be isolated from the environment so that they do not pose a danger to current or future generations. First, they can be placed deep underground in a stable geological environment. Second, a multi-barrier approach can be used to ensure that none of the radioactivity escapes. The wastes are immobilized by embedding them in stable, nondissolvable solid ceramic or glassy materials. They then can be sealed in ceramic or metal canisters, with absorbent mineral fillings packed around them. The entire assembly can be sealed in deep bedrock.
One of the fears expressed about nuclear waste storage is that the buried nuclear waste canisters might somehow, over very long time periods, be damaged, allowing radioactive materials to enter underground water. In fact, the toxicity of nuclear plant wastes after 1,000 years is about equal to the toxicity of the uranium ore from which the fuel originally was obtained. After about 4,000 years the nuclear waste is not more toxic than natural mercury, chromium, cadmium, silver, or many other ores. The multiple barriers will be selected, designed, and constructed to retain the radioactive wastes for 10,000 years.