What is the nuclear energy

Of all the uranium that can be found in nature, only 0.7% is made up of the Uranium-235 isotope. This is a very suitable element to be used as fuel in nuclear fission plants that produce electricity. But since the presence in natural uranium is so small, it is necessary to first submit it to a series of processes called enrichment and which achieve that the presence of this Uranium-235 isotope in nuclear fuel is around 3 to 5%.

Nuclear fission is a reaction by which certain nuclei of heavy chemical elements are "separated" into two fragments by the impact of another particle, a neutron, releasing other neutrons in the process and, at the same time, a large amount of energy that It manifests itself in the form of heat. The neutrons that are emitted or released in the fission reaction can cause, under certain circumstances, new fission of other nuclei. So, it is said that a nuclear chain reaction has occurred.

The enriched uranium that is used as fuel in power plants is generally encapsulated inside pellets made of ceramic material which, at the same time, are inserted into pods, 4 or 5 m long and 1 cm wide, made of steel. stainless steel or a zirconium alloy called zircaloy. These pods are grouped into packages that are called fuel elements. As fission reactions take place, the presence of enriched uranium in the fuel elements is less and less and after a while the fuel elements have to be changed. This process of change is called the loading process. When the fuel elements are extracted, they remain submerged in water for about 10 years, until their radioactivity decreases enough so that there is no danger when transported. After this time, the uranium present in the fuel can be reprocessed again, or it can be stored in the so-called nuclear cemeteries.

Nuclear power plants take advantage of the heat released in the multiple nuclear reactions that take place in the core of the plant's reactor, to convert a liquid that circulates through a set of conduits into steam at a high temperature. Steam that is later used to produce electricity, as will be seen later.

The technology required in these plants is complex and, for this reason, in the beginning, it was the developed countries that began to use energy of nuclear origin to produce electricity. Currently, it is in Europe and North America where there are more facilities of this type; Specifically, in the United States, in the year 2000, there were a total of 104 power plants; in France, 59; in Germany, 20; and in Switzerland, 5. Spain has 9 plants of this type.