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Background
Nuclear energy is an alternative source of energy that is generated from the nuclei of atoms. Because the sources come from atoms of elements, which are naturally occurring elements in earth's crust, it is also considered to be a nonrenewable source of energy just like the fossil fuels — coal, oil, and natural gas. There are two types of nuclear reactions that can generate energy from the nuclei of atoms — nuclear fission and nuclear fusion.
Nuclear Fission
Nuclear fission is the most common nuclear reaction. In nuclear fission, a heavy nucleus splits releasing large amounts of energy. Uranium-235 and Plutonium-239 are the major types of isotopes atoms that have the same number of protons but different number of neutrons whose nuclei are able to sustain a fission chain reaction. This is able to occur because the nuclei of these elements release neutrons a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen |
Nuclear Fusion
Another form of nuclear energy is nuclear fusion. Nuclear fusion releases energy when two or more nuclei join — or fuse — together to form a heavier nucleus. Nuclear fusion is the process that generates the light energy that is emitted from stars, such as the sun. In this nuclear reaction, hydrogen atoms fuse together to form helium atoms and energy is released. Nuclear fusion offers a chance for an almost inexhaustible source of energy. However, it takes considerable heat energy to force nuclei to join/fuse. This is why the use of nuclear fusion as a source of energy for people/society is not feasible today.
Atomic cloud over Hiroshima from Little Boy bomb, taken from "Enola Gay" flying over Matsuyama, Shikoku
Nuclear Energy
Since 1945, scientists have been giving attention to using nuclear fission as a source of energy for generating electricity. There are two types of nuclear power plants in the United States — the Pressurized Water Reactor (PWR) and the Boiling Water Reactor (BWR). You can visit Student's Corner - Nuclear Reactors and see how these two different systems work.
Uranium-235 is the fuel of choice for commercial nuclear reactors. When nuclear fission occurs, energy is released in the form of heat and electromagnetic radiation light . In commercial reactors, the heat energy released from the fission reaction is used to heat water into steam and that steam is used to turn turbines that generate electricity. According to the U.S. Energy Information Administration, there are currently 61 commercially operating nuclear power plants with 99 reactors in the United States in 30 states. You can visit Operating Nuclear Power Reactors and see a map of the nuclear power plants and reactors in the United States. You can click on the sites in each state to learn about the plant and what type of reactor each has — PWR or BWR.
Map of nuclear power plants in the United States. Note that they are more heavily clustered on and east of the Mississippi River.
Since nuclear power plants first began being used to generate electricity, there have been many accidents and incidents that have caused harm to the environment and people that live in those areas. These accidents are ranked on a scale of 1 to 7 with 7 being the worst. Read about the worst nuclear accidents. There has only been one 7 ranking in history, Chernobyl in 1986. Watch Chernobyl Disaster to get a glimpse of what happened in Chernobyl. Login information
Nuclear Bombs
The science of atomic radiation, atomic change, and nuclear fission were studied and developed from 1895 to 1945. Nuclear fission was beginning to become important in the 1930s. During the late 1930s to the mid 1940s, nuclear fission was focused on the development of the nuclear/atomic bomb. In World War II, the United States used two types of atomic bombs on Japan. One of the bombs had a uranium core and the other bomb had a plutonium core. Both caused nuclear fission reactions. The uranium core bomb was known as "Little Boy" and was dropped on Hiroshima and the plutonium core bomb was known as "Fat Man" and was dropped on Nagasaki. This ultimately resulted in the end of World War II.
Pros and Cons
Nuclear energy and fossil fuel energy are both nonrenewable sources of energy. When comparing the benefits of generating electricity from nuclear energy and fossil fuel energy, nuclear energy is a more efficient source of energy.
Pros
- Nuclear energy has a 91 percent rate of efficiency — compared to coal which has a 58.9 percent rate of efficiency. This means that it takes less material — Uranium — to produce the same amount of energy as coal.
- Nuclear energy is also cleaner for the atmosphere. There are very little greenhouse gases emitted into the atmosphere during the generation of electrical energy. Even though nuclear energy is not directly responsible for releasing greenhouse gases into the atmosphere, the processes of mining, refining, and transporting the uranium does contribute to greenhouse gases being emitted into the atmosphere. These processes require equipment that has engines using the combustion of fossil fuel for the energy to do work.
Cons
There are still other environmental concerns from using nuclear energy to generate electricity.
- Nuclear power plants require large amounts of water to produce the steam and for cooling. The water is released back into rivers at a higher temperature and this can affect the quality of the water, thus affecting the fish and other aquatic organisms that live there.
- Every 18 to 24 months, nuclear power plants have to be shut down to remove and replace the used uranium fuel. This used fuel is now radioactive wastes and has to be properly stored to prevent the environment from becoming contaminated. This waste is stored at the nuclear power plants in steel lined, concrete vaults filled with water or above-ground steel or steel-reinforced concrete containers with steel inner canisters. Exposure to this radiation can cause cancer, birth defects and abnormalities, and death if the exposure is great enough.
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