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Uranium - nuclear fuel

Uranium - nuclear fuel

Uranium is the most commonly used nuclear fuel in nuclear fission reactions. It is a natural element that can be found in nature. However, in order to be able to use uranium in a nuclear reactor it must undergo some treatment.


To know the peculiarities that make uranium so different from the other substances we must first consider some basic nuclear physics.


Basic physical considerations An atom of a nucleus and of electrons that surround this nucleus. In turn, a nucleus consists of protons and neutrons. A proton has a positive charge. A neutron has no electric charge and is neutral.


The positive charges of the protons try to push violently outwards. What prevents them from separating is a new kind of force: an immensely powerful short-range attraction force, acting indistinctly between protons and neutrons (which from this point of view are all nucleons). The short-range nuclear force holds them together, opposing the repulsive effect of positive charges on protons. In this way, neutrons act as & ldquo; nuclear cement. & Quot ;.Characteristics of uranium, an unstable element

The nucleus of a uranium atom contains 92 protons. Under these conditions the repulsive force among the protons is about to overcome the nuclear force.

Atoms of the same element may belong to different isotopes depending on the number of neutrons they contain.

If there are 146 neutrons in the nucleus of the uranium atom, it is in an unstable state. This form of uranium containing a total of 238 nucleons (92 protons and 146 neutrons) is called uranium-238.

The next most likely arrangement is a uranium nucleus containing three minus neutrons: uranium-235. The atoms with these lighter nuclei make up about 0.7% of the naturally occurring uranium.

Both cases are the same element, uranium, since they have 92 protons. However, they belong to different isotopes because one has 238 neutrons and the other 235.

The uranium-235 core is already under stress close to internal rupture; A stray neutron approaching it can break it completely.

For nuclear fission reactions we are interested in this combination of protons and neutrons that is so on the verge of overcoming the nuclear force. Thus, by simply adding a neutron to the atom it explodes and divides, generating other neutrons that can collide with other uranium atoms that are also at the limit.

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Last review: April 27, 2017