![]() These enormous differences may explain why nuclear energy is highly attractive in terms of energy economics, but on the other hand, because of the enormous energy density that must be controlled, it requires a particularly high degree of responsibility and care concerning the safety of nuclear power plants. The difference in the strength of the interactions is also expressed in another figure: The decomposition of a heavy atomic nucleus into two moderately heavy nuclei results in an amount of energy about 400,000 times greater than in chemical reactions between whole atoms. When heavy nuclei split into two medium-heavy ones, the difference in binding energies is released in the form of heat by the motion of the fission products. After that, it drops slightly to the heavy elements. It is not constant for the elements, but increases from the lightest element, hydrogen, at first very steeply and then more slowly up to the heavier elements such as krypton. The decisive factor here is the magnitude of the binding energy per nucleon in the nucleus. Therefore, the nuclei of the atoms play a decisive role in the resulting nuclear energy. In nuclear energy, there is a much larger strong interaction that binds the nucleons together. In combustion, the underlying chemical processes take place in the electron shell of atoms which results in electromagnetic interaction. The reason for these enormous efficiency differences lies in the usage of two natural forces with different degrees of interaction. The energy yield per pound of fuel in nuclear fission is about 5.5 million times higher than that of burning hard coal (2.5 million times per kilogram). This corresponds to combustion energy of about 5,500,000 pounds (2,500,000 kilograms) of hard coal with an energy content of 3200 kilocalories per pound (7000 kilocalories per kilogram). Applying Einstein’s relationship E=mc 2, this gives a value of about 25 million kilowatt-hours. When 1 kilogram (2.2 pounds) of U-235 is fissioned, only about one gram of mass is lost (one part in a thousand), which is converted into heat energy. The process of nuclear fission is very efficient. The enormous amounts of energy released during nuclear fission make nuclear power a genuine energy source. Controlled chain reactions take place in nuclear reactors of nuclear power plants. Such a moderated chain reaction is called a controlled ( nuclear power) chain reaction. However, certain materials can be used to limit the number of neutrons to moderate the chain reaction. Uncontrolled chain reactions occur in atomic bombs. If this chain reaction is not moderated, it is called an uncontrolled chain reaction ( nuclear weapons). The result is a reaction that continues by itself called a chain reaction. If the neutrons released during nuclear fission meet other fissile material with the “right” speed, they can cause further nuclear fissions. The chain reaction in fission Nuclear fission. This is about 640.000 times the energy released when 1 pound of hard coal is burned (290,000 times for 1 kg). If we consider the number of atomic nuclei contained in a kilogram of uranium and assume that they all decay, the energy released from the fission of uranium is then 8.6 x 10 12 J. ![]() There are 2.6 x 10 24 amount of atoms in Uranium-235. However, this refers to one nuclear decay of an atom. When a uranium nucleus fissions, an energy of about 3 x 10 -11 Joule is released. According to the E=mc 2 discovered by Albert Einstein in 1905, the reduction of mass corresponds to released energy. In nuclear fission, the mass of the initial nucleus plus the absorbed neutron is greater than the mass of the nuclei being created, including the neutrons being released. Therefore no CO 2 is released into the atmosphere. There is no chemical reaction taking place in nuclear fission unlike in the combustion of fossil fuels. Nuclear fission releases energy because the fission reaction converts mass into energy. Why does nuclear fission release energy? Image credit: Marko Aliaksandr/
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