What is a nuclear reactor

The words "nuclear reactor" are now familiar to all, in fact, becoming a symbol of an entire era. Despite the potential danger of using such devices, in the light of the depletion of world oil reserves, nuclear fuel reactors are very promising.

The nuclear reactor is an engineering device in which a controlled fission reaction of a fissile radioactive substance occurs , accompanied by the release of energy. The main purpose is the generation of electric current (nuclear power plants - nuclear power plants), as well as the production of heavy fissioning elements of the Periodic Table of Mendeleev (transformation). The first nuclear reactor was assembled and put into operation in 1942 in America under the control of the outstanding physicist of his time - Enrique Fermi. Three years later, Canada launched its reactor, and in 1946 - Russia.

Let us note one important point: many people unfamiliar with this topic often believe that a nuclear reactor produces electricity directly, and it is a by-product of fissionable radioactive fuel. Unfortunately, it is not. In fact, the nuclear reactor is a huge heater, if not to say a "boiler" that supplies heat to the heat carrier, which makes useful work of generating electricity through a conventional generator.

To answer many questions, let us consider the device of a nuclear reactor. Structurally, any nuclear reactor includes the following elements:

- a central active zone with a fast neutron moderator. It is here that the fission reaction takes place;

- layer reflecting neutrons. It is necessary to reduce the penetrating ionizing radiation, as well as to increase the efficiency of the installation;

- protection against radiation. As a rule, lead shields;

- coolant. In all modern reactor models is an indispensable part;

- rod device for controlling the flow by the nuclear decay reaction;

- Cooling circuit;

- remote control mechanism.

Heavy metals - Uranium-233, 235 or Plutonium-239 - are used to operate boilers of nuclear reactors. The peculiarities of these elements are that spontaneous decay (splitting) occurs in each atomic unit in each unit of time. In this process neutrons are released from the atomic nuclei. An atom that has lost (acquired) a neutron turns into another element of the periodic table. For example, in this way, Plutonium-239 is obtained from Uranus-238. Striking along the neighboring atoms of the fuel material, they, due to their high speed, release additional neutrons. The total number increases in the progression - the chain reaction of fission of nuclei begins . If, at this stage, no measures are taken to regulate it, the result will be an uncontrolled nuclear chain reaction accompanied by an avalanche release of an enormous amount of energy (a nuclear explosion).

Two mandatory methods are used for control: the introduction into the active zone of a moderator, which reduces the neutron velocity to the level of a self-sustaining process, and the introduction of the necessary number of control rods (cadmium or boron) absorbing an excess of neutrons.

When the nuclei decay, heat is released, which heats the circulating coolant (water), it is converted into steam and rotates the turbine of the electric generator.

This is the basic scheme. There are several of its varieties. For example, the heat transfer water can be naturally boiling or under pressure. The latter makes it possible to obtain superheated steam, increasing the efficiency. In addition, water is not the only type of coolant (it can be gas or liquid metal). Also, in some modifications of the reactors, the retarder is not used.