VVER-50E reactor

The VVER-50 reactor is a water-cooled, heterogeneous, vessel-type reactor operating on thermal neutrons with a water-water coolant-moderator (pressurized water). The VVER-50 reactor is of the integral type with natural circulation of the coolant, all the equipment of the first circuit is placed in one steel case, the length of pipelines is reduced to a minimum. The reactor is a vertical cylindrical vessel with an elliptical bottom, inside which the core, steam generator modules and internals are located. The top of the reactor is hermetically sealed with a lid with the drives of the reactor control and protection mechanisms and controls, and pipes for the output of the cables of the reactor monitoring sensors. The lid is attached to the body with studs.

In the upper part of the hull there are pipes for the supply and removal of the coolant, as well as pipes for the emergency supply of the coolant in case of depressurization of the primary circuit. 

The reactor has a natural coolant circulation. The water of the first circuit, cooled in the steam generator, passes down the annular gap between the hull and the shaft inside the vessel, then enters the fuel assembly through the perforated elliptical bottom and support pipes of the shaft. From the fuel assembly through the perforated bottom plate of the BZT, the coolant enters the annulus space of the BZT, into the annular gap between the shaft and the hull, and into the steam generator.

Water is heated in the core due to the heat generation of fuel cells (fuel elements). The fuel rods are filled with low-enriched uranium-235 dioxide. 

Regulation of reactivity and, thus, heat generation is carried out by moving the control elements with a solid absorber, as well as by changing the concentration of boric acid in the coolant.

The steam generator occupies an annular space above the core, enclosing the pipe with the upward flow of the heated coolant. The steam chamber above the steam generator acts as a volume compensator.

The reactor is started by lifting the control rods of the CPS: the core is warmed up, the pressure in the vessel is raised to the operating pressure, steam from the steam generator is supplied to the turbine generator, from which the auxiliary equipment is powered. The reactor responds quickly to changes in load.

The reactor is installed in a modular vessel, which provides reliable attachment of the reactor and biological protection. The design of the reactor and the method of its fastening, as well as the control, protection and emergency cooling systems of the zone ensure safe shutdown, cooling and structural strength.