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Nuclear fission energy has been the energy that has generated more controversy, often by being linked to the common citizen to military devices and many other times by ignorance of all the potential that has this kind of energy.
Nuclear fission power not only follows the release of electromagnetic energy-related links between electrons, protons and atoms, but occurs with the mass conversion of matter into energy. As we will see below, this makes it the largest release of energy that can be obtained from the field.
In 1942, Enrico Fermi has set in motion the first nuclear reactor. Since then nuclear power has been look of the most diverse forms. Earlier seemed it is a clean energy and without risks.
However, time has shown us the opposite with nuclear disasters as Windscale (1957), Three Mile Island (1979) and Chernobyl (1986), and serious problems such as waste and nuclear weapons.
Nuclear fission power not only follows the release of electromagnetic energy-related links between electrons, protons and atoms, but occurs with the mass conversion of matter into energy. As we will see below, this makes it the largest release of energy that can be obtained from the field.
In 1942, Enrico Fermi has set in motion the first nuclear reactor. Since then nuclear power has been look of the most diverse forms. Earlier seemed it is a clean energy and without risks.
However, time has shown us the opposite with nuclear disasters as Windscale (1957), Three Mile Island (1979) and Chernobyl (1986), and serious problems such as waste and nuclear weapons.
Enrico Fermi (1901-1954).
Nuclear power may in theory be achieved by two methods: nuclear fission and fusion. The first is the energy that is obtained from the fission of heavy nuclei with formation of smaller nuclei and the second corresponds to the energy released when two nuclei come together to form a new nucleus of a greater number of mass.
Most nuclear power plants that are currently used for the production of electricity from nuclear fission are using the uranium-235 isotope as fuel through a chain reaction induced by neutron collision. However, the uranium-238 isotope is the most abundant in nature and represents 99.3% of the total uranium. This isotope rarely undergoes fission and mostly captures neutrons producing plutonium and neptunium without significant release of energy. Therefore, the uranium used in the core has to be artificially enriched in uranium-235 increasing its percentage from the 0.7% that occur in nature up to 3% used in the mixtures of nuclear power plants.
Most nuclear power plants that are currently used for the production of electricity from nuclear fission are using the uranium-235 isotope as fuel through a chain reaction induced by neutron collision. However, the uranium-238 isotope is the most abundant in nature and represents 99.3% of the total uranium. This isotope rarely undergoes fission and mostly captures neutrons producing plutonium and neptunium without significant release of energy. Therefore, the uranium used in the core has to be artificially enriched in uranium-235 increasing its percentage from the 0.7% that occur in nature up to 3% used in the mixtures of nuclear power plants.
Scheme of a nuclear fission chain reaction of uranium-235.
(Credit: Serway&Jewett,Physics for Scientists and Engineers-with Modern Physics, 6th Ed., Thomson-Brooks/Cole, USA)
This percentage and conditions of temperature and pressure control achieved by the nuclear reaction is self-sustaining, or to the fact that at least one of the neutrons released in the fission of being caught by another uranium-235 isotope and not by an uranium-238 isotope.
The following image schematically represents the operation of nuclear power plants that are currently used to produce electricity commercially.
The following image schematically represents the operation of nuclear power plants that are currently used to produce electricity commercially.
Scheme of a nuclear fission reactor.(Adapted from Serway&Jewett,Physics for Scientists and Engineers-with Modern Physics, 6th Ed., Thomson-Brooks/Cole, USA)
At the core of the reactor the nuclear fissions of uranium-235 rise the temperature of the water in the primary circuit which is a closed circuit. This water is at high pressure in order not to boil and serves as a moderator of the speed of the neutrons that are released in order to prevent their fusion with the uranium-238 isotopes.
A nuclear reactor with tipical blue of the Cerenkov radiation. Credit: Wikipedia
The hot water of the reactor is then pumped through a heat exchanger which transfers heat through the walls of the pipe to the water in the secondary circuit. This water reaches boiling point and the vapour moves the paddle of a turbine connected to a generator of electrical power. The steam then passes a condenser that cools it back to liquid state. Water is then pumped back to the secondary circuit where the cycle restarts. The electricity produced by the turbine and generator per mass of uranium-235 is enormous compared to the energy produced by the same mass of fossil fuel.
Though the safety of the nuclear power plants increases with the new generations of reactors, nuclear waste will always be a problem because some of the radioactive waste will endure for thousands of years. On the other hand uranium, as fossil fuels, is a non-renewable source. Therefore it cannot solve the energy problem of the generations to come.
Though the safety of the nuclear power plants increases with the new generations of reactors, nuclear waste will always be a problem because some of the radioactive waste will endure for thousands of years. On the other hand uranium, as fossil fuels, is a non-renewable source. Therefore it cannot solve the energy problem of the generations to come.
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