Humanity requires more and more energy. The predictions made about the growth of development of new energy technologies, and the energy consumption were not correct. The energy consumption level is growing much faster than predicted. At the same time, the new sources of energy on an industrial scale and at competitive prices will start working no earlier than 2030. A shortage of fossil energy gets sharp. The possibility of building new hydropower plants is also very limited. The fight against the “greenhouse effect” restricts the burning of oil, gas and coal in thermal power plants.
The solution may be an active development of nuclear energy, one of the youngest and fast-growing sectors of the global economy.
Nowadays, many people say that nuclear energy is discredited. People have the impression that after the tragic events at nuclear power plants in Japan, most countries refuse to develop this area of energy. However, even Japan, which recently said about the closure of all nuclear power plants in the country, changes its mind. The Government of Japan has declared its readiness to review the plans for the use of nuclear power in the direction of the continuation of their exploitation.
Nuclear energy is the energy contained in the nuclei and released in nuclear reactions. It refers to the long-term and relatively cheap forms of energy.
This energy is released as a result of an internal restructuring of atomic nuclei. Nuclear energy can be obtained from nuclear reactions or radioactive decay of nuclei. The main methods of nuclear energy production are the fission of heavy nuclei and the fusion of light nuclei. The latter process is also known as thermonuclear reactions.
Division occurs by dividing of one atom by two. The splitting happens when the atoms bombarded by particles of atoms, such as neutron. The heat released by cleavage is used to generate steam directed to turbines that generate electricity basically the same manner as in thermal power stations.
Not every atom bombardment leads to its breakdown. Most of the atoms cannot be split. But the atoms of uranium and plutonium under appropriate conditions decompose radioactively.
One type of uranium is uranium-235. When uranium-235 is bombarded with neutrons it splits into two parts. The products of decay are usually two fission products, such as krypton or barium, and two or three neutrons. It takes time no more than few seconds and is accompanied by the emission of three neutrons. The increase in the number of neutrons in the fission process opens the possibility of a chain reaction of nuclear fission.
One kilogram of uranium-235 releases a million times more energy than is released during the combustion of one kilogram of coal. A small piece of uranium can provide the work of the whole ocean ship, aircraft or generator.
In the synthesis reaction, two atoms fuse together and form a single atom. Enormous energy releases as heat when connecting atoms. Most of the solar energy is the result of a fusion reaction that occurs in the sun.
These reactions usually occur with the release of energy, as formed by the merger of heavier nucleus nucleons are bound stronger. They have, on average, greater energy than in the initial fusing nuclei. The excess total energy of the nucleons, in this case, is released in the form of kinetic energy of the reaction products. These reactions occur at high temperatures since the merger of light nuclei must approach to a distance equal to the radius of the nuclear forces of attraction. This happens at the distances of cm ≈10 -13. Positively charged nucleus experience the Coulomb repulsion when they are outside of the nuclear forces of attraction. Only the cores that are flying toward each other at high speeds, such as included in the very hot environments or specially accelerated ones, are capable to overcome this repulsion. The rate of a fusion reaction is extremely small at energies below a few KeV, but it is growing rapidly with the growth of the nuclear kinetic energy, entering into the reaction.
Considering the dependence of the specific nuclear binding energy of the mass number A (the number of nucleons in the nucleus) is an explanation of the appearance of the two main sources of nuclear energy. Specific binding energy ε shows what the average energy is necessary to provide to the individual nucleons to release all the nucleons from this core.
The specific energy is at the maximum for the nuclei in the area of iron (A = 50 – 60), and decreases sharply during the transition to a light nucleus, consisting of a small number of nucleons, and decreases smoothly during the transition to heavy nuclei with A> 200.
Because of this dependence on ε and A there are two ways to obtain the above-mentioned nuclear energy. In both processes, a transition to the nuclei in which the nucleons bound stronger is made, and a part of the nuclear binding energy is released.
The fission method of energy production is used in a nuclear reactor and nuclear bomb. Nuclear fusion is used in the developing of a thermonuclear reactor and a thermonuclear bomb.
These ways of energy production are a record in terms of energy per unit mass of fuel. For example the complete fission of 1 gram of uranium releases energy around 10 11 J. That is roughly the same as the explosion of 20 kg of trinitrotoluene. Therefore, nuclear fuel is 10 7 times more efficient than chemical fuel.
Nuclear power plants pollute the environment, as well as power plants running on fossil fuels. If emissions of conventional power plants include the already familiar to us chemicals, nuclear power plants emissions include radioactive elements, which are almost entirely a product of fission reactions.
The cleavage products contain radioactive isotopes of krypton, xenon, cesium, rubidium, barium, strontium, iodine and bromine isotopes of hydrogen and tritium. Other isotopes generated in the cooling water, including isotopes of argon, fluorine, hydrogen and oxygen. A number of other isotopes produced in materials surrounding the reactor core.
In general, nuclear power is a highly effective energy source. Under normal conditions, nuclear power stations do not generate significant air pollution. They are able to meet the growing future energy needs replacing fuels, highly polluting the atmosphere and storing them as raw material for industry. On the other hand, the possibility of accidental discharge of radioactivity is still a concern, so that the popularity of nuclear power stations is rather low, which hampers the implementation of the program of nuclear energy in North America and Europe. In addition, uranium reserves, as well as oil and coal are limited and are likely to be depleted in a few centuries. Until then, nuclear power should be studied deeply and considered as a significant energy source.