VVER

VVER (Russian: ВВЭР, which stands for Vodo-Vodyanoi Energetichesky Reactor; English: Water-Water Energetic Reactor) is a series of pressurized water reactor designs originally developed in the Soviet Union, and now Russia. The VVER is the most widely installed type of nuclear reactor in the world.

Design and operation

The VVER design is a type of pressurized water reactor (PWR). In a PWR, the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy generated by the fission of atoms. The heated water then flows to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and flows to turbines which, in turn, spin an electric generator.

In a VVER, the coolant water is also the neutron moderator which slows down neutrons from the fission to sustain the nuclear chain reaction. The water in the reactor core reaches about 320°C, hence it must be kept under about 150 times atmospheric pressure to prevent it from boiling.

Safety features

VVER reactors have several safety features. They have a large containment building to contain any accidental releases of radioactivity. The reactors are also designed with a negative void coefficient, meaning that if water in the reactor core is replaced by steam (or any other substance), the nuclear reaction rate decreases.

Types of VVER

There are several models of VVER reactors. The earliest model, the VVER-440, was designed and built in the 1960s and 1970s. The VVER-1000 (or VVER-1200 in more recent versions) is a larger and more modern design with a higher power output.

VVER reactors around the world

VVER reactors are used in many countries, including Russia, Ukraine, Finland, Hungary, Czech Republic, Slovakia, Bulgaria, India, Iran, and China. They are also being considered for use in other countries, such as the UK.

See also

• Nuclear power
• Nuclear reactor technology
• Pressurized water reactor
• Nuclear power in Russia