words "nuclear reactor" is now familiar to all, in fact, becoming a symbol of an era.Despite the potential danger of using such devices in the light of the depletion of world oil reserves reactors nuclear fuel it is very promising.
nuclear reactor is the engineering unit, in which the controlled fission of fissile radioactive material, accompanied by the release of energy.The main purpose - the generation of electric power (nuclear power plants - nuclear power plants), as well as obtaining fissionable heavy elements of the periodic table (conversion).The first nuclear reactor was assembled and put into operation in 1942 in the United States under the supervision of the eminent physicist of his time - Enrico Fermi.Three years later, Canada has launched a reactor, and in 1946 - Russian.
note one important point: many people unfamiliar with the subject, often believe that a nuclear reactor generates electricity directly, and it is a byproduct of radioactive fissile fuel.Unfortunately, it is not.In fact, a nuclear reactor is a huge heater, to say the "boiler", according to the thermal energy to the heat carrier, which performs useful work on the production of electricity by means of a conventional generator.
to answer many questions, consider a device of a nuclear reactor.Structurally, any nuclear reactor includes the following elements:
- central active region of fast neutrons with the moderator.This is where the fission reaction;
- reflecting layer neutrons.It is necessary to reduce penetration of ionizing radiation, and also to improve efficiency of the apparatus;
- protection against radiation.Typically, lead shields;
- coolant.All current models of reactors is an essential part;
- rod control device during the reaction nuclear decay;
- the cooling circuit;
- remote administration.
For boilers nuclear reactors use heavy metals - uranium-233, plutonium-235 or 239.The features of these elements is that each unit of time in their atomic structure comes spontaneous decay (splitting).In this process of atomic nuclei released neutrons.An atom that has lost (acquired) a neutron turns into another element of the periodic table.For example, in a manner of Uranium-Plutonium-238 is prepared 239.Striking on adjacent atoms of the fuel material are, due to their high speed, releasing additional neutrons.Total increases in progression - starting a chain reaction of nuclear fission.If at this stage does not take measures to regulate it, the result will be an uncontrolled nuclear chain reaction, accompanied by an avalanche release enormous amounts of energy (nuclear explosion).
used to control the two mandatory method - an introduction to the core moderator, slowing the neutrons to a level of self-sustaining process, as well as making the required number of control rods (cadmium or boron), absorbing excess neutrons.
the decay of nuclei generates heat, which heats the circulating coolant (water), it is converted into steam turns a turbine and electric generator.
This is the main circuit.There are several varieties of it.For example, water-coolant may be natural or boiling under pressure.The latter allows to obtain superheated steam, increasing efficiency.Furthermore, water - not the only carrier (may be a gas or a liquid metal).Also, in some embodiments reactors retarder is used.
