VVER

WWER-10ff (also VVER-1000 as a direct translitteration from Russian ВВЭР-1000). WWER-1000 (Water-Water Energetic Reactor, 1000 megawatt electric power) is a Russian energetic nuclear reactor of PWR type.

The VVER (Vodo-Vodyanoi Energetichesky Reactor or WWER) (Russian: Водо-водяной энергетический реактор) is a series of pressurised water reactors that were developed and used by the former Soviet Union and its satellites, as well as the present-day Russian Federation. The VVER was a more expensive reactor design, and the former Soviet Union opted for the graphite-moderated RBMK series nuclear reactors on the grounds of cost as well as the ease of re-fueling the RBMK while the reactor was still operational compared to the VVER which needed to be shut down to be re-fueled and is of a much safer design.

The earliest VVERs were developed before 1970. The most common design, the VVER-440 Model V230, employs six primary coolant loops, each with a horizontal steam generator. The modified version of the VVER-440, Model V213, was a product of the first uniform safety requirements drawn up by the Soviet designers. This model includes added emergency core cooling and auxiliary feedwater systems as well as upgraded accident localization systems. The larger VVER-1000 design, which was developed after 1975, is a four-loop system housed in a containment-type structure with spray type steam suppression system.

The VVER series nuclear reactors were also scaled down in size and was used by the Soviet Navy's nuclear submarine fleet as well as by surface warships.

The Russian abbreviation VVER stands for water-cooled, water-moderated energy reactor. This means, that the reactor is of the pressurized water reactor (PWR) design. The fuel is low enriched (ca. 2.4–4.4% ²³⁵U) uranium dioxide (UO2) pressed into pellets and assembled into fuel rods. These fuel rods are fully immersed into water that is kept under pressure (15 MPa) so that it cannot boil. This water serves both as coolant and moderator, which guarantees intrinsic safety under normal circumstances: Should the circulation fail, the moderating effect diminishes, thus reducing the intensity of the reaction to compensate the loss of cooling (negative void coefficient). The whole reactor is encased in a massive steel pressure-shell.

The intensity of the nuclear reaction is controlled by control rods that can be inserted into the reactor from above. These rods are made from a neutron absorbing material and depending on the depth of insertion hinder the chain reaction. In the case of emergency, an emergency switch-off can be performed by full insertion of the control rods into the core.

Primary cooling circuit

As stated above, the water in this circuit is kept under constant pressure to avoid boiling. Since this water removes all the heat from the core and is irradiated, the integrity of this circuit is most crucial. In this circuit four distinct stations can be distinguished:

1. Reactor: The water flows through the fuel rod assemblies, removing the heat supplied by the nuclear chain reaction
2. Pressurizer: To keep the water under constant but not over-high pressure, the pressurizer regulates the pressure by means of electrical heating and relief valves.
3. Steam Generator: In the (horizontal) steam generator, the heat from the primary water is used to boil water from the secondary circuit.
4. Pump: The pump ensures the proper circulation of the water through the circuit.

To ensure safety, the components are redundant.

Secondary circuit and electrical output

The secondary circuit consists also of different stations:

1. Steam Generator: Secondary water is boiled, removing heat from the primary circuit. Before exiting, the remaining water is removed from the steam, so that the steam is dry.
2. Turbine: The expanding steam drives the turbine, which is connected to the electrical generator. The turbine is split into a high- and a low-pressure part. To prevent condensation (Water droplets at high speed damage the turbine blades) the steam is reheated between the sections. Reactors of VVER-1000 type deliver 1GW of electrical power.
3. Condenser: The steam is cooled down and is allowed to condense by delivering its heat to a cooling circuit
4. Deaerator: Removes gases from the coolant
5. Pump: The circulation pumps are driven by small steam turbines of their own

To increase the efficiency of the process, steam from the turbine is taken to reheat the coolant before the deaerator and the steam generator. Water in this circuit is not supposed to be radioactive.

Cooling circuit

This is an open circuit, the water is usually taken from an outside reservoir like a lake or river. In order not to heat the reservoir too much, thus polluting the environment, cooling basins (or cooling towers) allow the water to cool down before reentering the reservoir.

Safety barriers

A typical design feature of nuclear reactors are layered safety barriers preventing escape of radioactive material. The VVER reactors have four layers:

1. Fuel pellets: Radioactive elements are retained within the crystal structure of the fuel pellets
2. Fuel rods: The zircaloy tubes provide a further barrier resistive to heat and high pressure.
3. Reactor Shell: A massive steel shell encases the whole fuel assembly hermetically.
4. Reactor Building: The concrete containment building that encases the whole first circuit is strong enough to resist the pressure surge a breach in the first circuit would cause.

Unlike some other modern designs, the VVER does not include a containment building sufficiently strong to shield the reactor from outside incidents such as airplane crashes.

VVER-1200

The VVER-1200, an evolutionary design of the VVER-1000, is being offered for export. Specifications include a $1200/kW-electric capital cost, a 54 month planned construction time, and an expected 50 year life at a 90% capacity factor.

Power plants

Partial list of operational VVER installations

Power plant	Country	Reactors	Notes
Balakovo	Russia	4 × VVER-1000/V320 (2 × VVER-1000/V320)	Unit 5 under construction, operational 2008. Construction of unit 6 was halted 1993.
Belene	Bulgaria	(2 × VVER-1000/V446B)	Under construction, operational 2013/2014
Bohunice	Slovakia	2 × VVER-440/V230 2 × VVER-440/V213	Split in two plants, V-1 and V-2 with two reactors each.
Dukovany	Czech Republic	4 × VVER 440/V213
Kalinin	Russia	3 × VVER-1000/V338 (1 × VVER-1000/V338)	Unit 4 under construction.
Kola	Russia	4 × VVER 440/V230
Koodankulam	India	(2 × VVER-1000)	Under construction, operational 2007/2009 with four additional units planned.
Kozloduy	Bulgaria	2 × VVER-1000	4 × VVER-440/V230 decomissioned 2003-2006
Loviisa	Finland	2 × VVER-440
Metsamor	Armenia	2 × VVER-440/V230	One reactor was shut down in 1989.
Mochovce	Slovakia	2 × VVER 440/V213 (2 × VVER 440/V213)	Units 3 and 4 under construction, operational 2012
Paks	Hungary	4 × VVER-440/V213
Rivne	Ukraine	2 × VVER-440/V213 1 × VVER-1000 (1 × VVER-1000)	Unit 4 under construction
Temelín	Czech Republic	2 × VVER 1000/V320
Zaporizhzhia	Ukraine	6 × VVER-1000	Largest nuclear power plant in Europe

See the Wikipedia pages for each facility for sources.

External links

• THE KUDANKULAM ATOMIC POWER PROJECT
• Reactor VVER-1000, Rosenergoatom
• VVER Reactor, Virtual Nuclear Tourist
• VVER Design, International Nuclear Safety Center, Argonne National Laboratory
• The VVER-440/213 reactor type
• VVER Reactors, at the US Energy Information Administration site.