Nuclear Reactor

Fission of nuclei of isotope of uranium 235 takes place in nuclear reactor. The result of fission is origin of thermal energy and numerous radioactive isotopes.

Facility of the reactor is formed by a cylindrical pressure vessel manufactured from special steel with rustless lining. There are constructions imbedded inside of the reactor's vessel, which regulate flow of water through the active zone, create the bearing part of the active zone, serve for output of intrareactor measurement and regulation of reactor's performance and they have also other functions. During operation, reactor is firmly sealed with the cover, over which electric motor drives for control of movement of regulation cartridges are installed.

The most important reactor's part is the reactor's active zone, in which 312 fuel assemblies are placed. Each of fuel assemblies contains 126 hermetically sealed fuel rods made of zircon alloy, into which enriched uranium dioxide is loaded in form of ceramic pellets.

Regulation of nuclear reactor's performance is enabled by regulation cartridges composed of fuel and absorption parts. Absorption part of a regulation cartridge is manufactured from stainless steel with addition of boron, which absorbs effectively the thermal neutrons originating in the course of fission reaction. Only seven regulation cartridges share in regulation of reactor's performance itself, the others serve, in case of need, for a quick shutdown of reactor. In this case automatically, by their own weight, the upper absorption parts of all 37 regulation cartridges fall into the active zone. The reactor will be shut down during several seconds, independently of activity of the operating personnel.

Regulation of reactor's performance is possible also by means of liquid absorbers, boric acid, which is dissolved in cooling water of the primary circuit.