The big difference between a conventional power plant and a nuclear power plant is that the nuclear power plant produces heat through nuclear fission chain reactions.Ĭomprehending how nuclear power plants make electricity
#FISSION ENERGY DRINK GENERATOR#
The steam is then used to turn a turbine that’s attached to a generator that produces electricity. In this type of plant, a fossil fuel (coal, oil, natural gas) is burned, and the heat is used to boil water, which in turn is used to make steam. In many respects, a nuclear power plant is similar to a conventional fossil fuel power plant. That’s what scientists have done with nuclear power plants. If the neutrons can be controlled, then the energy can be released in a controlled way. The secret to controlling a chain reaction is to control the neutrons. Anything less than this amount is called subcritical.Ĭontrolling reactions: Nuclear power plants The minimum amount of fissionable material needed to ensure that a chain reaction occurs is called the critical mass. If they don’t hit a U-235 nucleus, no extra electrons and no energy are released. If the sample is small, then the neutrons are likely to shoot out of the sample before hitting a U-235 nucleus. This type of isotope is said to be fissionable, and only two main fissionable isotopes are used during nuclear reactions - uranium-235 and plutonium-239.Ī certain minimum amount of fissionable matter is needed to support a self-sustaining chain reaction, and it’s related to those neutrons. But isotopes that produce an excess of neutrons in their fission support a chain reaction. You can’t have a chain reaction with U-238. If you were to write the equation for the nuclear fission of U-238, the more abundant isotope of uranium, you’d use one neutron and only get one back out. This chain reaction depends on the release of more neutrons than were used during the nuclear reaction. The real trick, however, is to control the chain reaction, releasing its energy slowly so that ends other than destruction can be achieved. The chain reaction is uncontrolled, releasing a tremendous amount of energy almost instantaneously. When time comes for the bomb to explode, conventional explosives force the two pieces together to cause a critical mass. In an atomic bomb, two pieces of a fissionable isotope are kept apart. The first atomic bomb was dropped on Hiroshima, Japan, on August 6, 1945. The chain reaction of U-235 is shown in FigureĪTOMIC BOMBS (BIG BANGS THAT AREN’T THEORIES)īecause of the tremendous amount of energy released in a fission chain reaction, the military implications of nuclear reactions were immediately realized. In terms of nuclear chemistry, it’s a continuing cascade of nuclear fissions called a chain reaction. These three neutrons, if they encounter other U-235 atoms, can initiate other fissions, producing even more neutrons.
Notice that one neutron was used, but three were produced. For example, when a mole of U-235 decays to Th-234, the mass defect is 5 × kg, which when converted to energy amounts to 5 × joules! The speed of light is squared, making that part of the equation a very large number that, even when multiplied by a small amount of mass, yields a large amount of energy. You can actually calculate the amount of energy produced during a nuclear reaction with a fairly simple equation developed by Einstein: E = In this equation, E is the amount of energy produced, m is the “missing” mass, or the mass defect, and c is the speed of light, which is a rather large number. The following sections provide an overview of just what you need to know during your Chem I course about nuclear fission.Ĭalculating chain reactions and critical mass The missing matter is converted into energy. This loss of matter is called the mass defect. Where does the energy come from? Well, if you make very accurate measurements of the masses of all the atoms and subatomic particles you start with and all the atoms and subatomic particles you end up with and then compare the two, you find that some mass is “missing.” Matter disappears during the nuclear reaction. Reactions of this type also release a lot of energy. The nuclear fission of uranium-235 is shown in the following equation: The collision caused the larger isotope to break apart into two or more elements, which is called nuclear fission. Scientists usually accomplished this task by bombarding a large isotope with a second, smaller one - commonly a neutron. In the 1930s, scientists discovered that some nuclear reactions can be initiated and controlled (see Radioactivity and Man-Made Radioactive earlier in this chapter).
0 kommentar(er)
