2024-02-21 20:55:13
On May 2 of this year, the General Director of Rosatom State Corporation Alexey Likhachev and RA Prime Minister Nikol Pashinyan held a meeting in Yerevan, during which the issues of re-extending the period of operation of the Armenian NPP and the construction of new nuclear power units in Armenia were discussed. Alexei Likhachev emphasized that Rosatom is ready to offer nuclear power plants of Russian design with ВВЕР reactors, which are distinguished by high safety and economic efficiency.
In this article, we will try to explain as clearly as possible what ВВЕР is and why this type of reactor is considered safe.
What kind of reactors are there?
There are many different types of reactors around the world, including research, transportation, and power.
The research reactor is used for basic and applied scientific research.
Transport reactors are used on nuclear icebreakers. Such powerful seagoing vessels operate year-round in ice-covered waters.
Power reactors are nuclear reactors, the main purpose of which is the production of electrical and thermal energy. Such reactors are used in nuclear power plants. A nuclear power plant has been operating in Armenia for 47 years. The Armenian NPP is the only nuclear power plant in the South Caucasus, it produces more than a third of all electricity produced in Armenia. The station plays an important role in the energy system of Armenia and the entire socio-economic life of the country.
What is WWER?
Today, one of the safest and most reliable types of power reactors in the world is the Russian VVER project, a water-water power reactor. It is a representative of one of the most successful branches of the development of nuclear energy facilities.
A reactor is a pressurized vessel filled with water, in which assemblies containing nuclear fuel are immersed. The flow of water passing through them removes the generated heat. In other countries, the general name of this type of reactor is PWR (Pressurized Water Reactor), which is considered the basis of global nuclear energy. The first plant with such a reactor, the Shippingport NPP, was commissioned in the USA in 1957. The first ВВЕР was put into operation in 1964 in power unit No. 1 of the Novovoronezh NPP, a first-generation power reactor. Later, second generation reactors appeared, they were already in series and were built all over the world, including in Armenia.
WWER in Armenia
The first power unit of the Armenian NPP with the ВВЕР-440 reactor was put into operation in December 1976, the second – on January 5, 1980. The NPP was the only plant in the USSR located in a seismic zone and far from significant water resources. It is for this reason that the ВВЕР-440 reactor plant was modernized, and its В-270 modification was prepared to build a nuclear power plant in Armenia.
On December 7, 1988, an earthquake with a magnitude of more than 7 (MSK-64) occurred in Armenia. And although the nuclear power plant has fully preserved its working capacity, the leadership of the republic has decided to stop the operation of the ANPP. Later, taking into account the energy situation, the blockade of transport communications and the lack of its own energy carriers, the RA government adopted a decision “On starting restoration works and resuming the operation of the second power unit of the Armenian NPP”. On November 5, 1995, after a pause of more than 6 years, the 2nd power unit of the ANPP was put into operation. Armenia’s national energy expert Ara Marjanyan also speaks about the safety of this type of reactors at the UN. “ВВЕР technology is being considered as a new reactor for the future nuclear power plant in Armenia. ВВЕР reactors have proven their reliability and efficiency all over the world. Blocks similar to the Armenian one have been successfully operated in more than 10 countries of the world for nearly 50 years. Therefore, the choice of this type of reactor is justified and correct. At one time, an earthquake-resistant version of the ВВЕР-440 reactor plant, the so-called “В-270 product”, was developed specifically for Armenia. The works were carried out by the Russian “Gidropres” Institute and “Izhor Factory”. They were installed in the Armenian NPP. Let’s remind that during the destructive earthquake of Spitak in 1988, the automation of the Armenian NPP did not even turn off the power units, and the plant continued its normal operation. It should be noted that the strength of the tremors in the epicenter was 9 points (MSK 64), and in the territory of the NPP – 5.5 points. Today, we can state with full confidence that the type of VVER reactors and the location of the nuclear power plant were chosen correctly for the Armenian NPP.”
In 2021, large-scale modernization and re-equipment works were carried out at the nuclear power plant, due to which its operation period was extended until 2026. Now the nuclear power plant is entering the second stage of modernization. It is planned to carry out re-extension measures that will increase the service life by another 10 years until 2036.
Can a nuclear power plant withstand an earthquake?
Of course, considering the seismic activity of the region, this issue is one of the most important.
1988 During the Spitak earthquake, the equipment of the Armenian nuclear power plant, as well as the buildings and structures, withstood the shock, which experts estimated, according to the plant’s instruments and the indications of the nearby seismic centers, was 6.25 points on the Richter scale. The strength of the buildings was ensured by hydraulic shock absorbers, which in the event of an earthquake connected the foundation (monosalic) and the equipment, preventing the latter from moving under the influence of shocks and inertia. The reliability of the equipment and the correct actions of the personnel allowed to avoid the accident, as well as to prevent panic among the population.
In the case of a modern generation 3+ reactor, even in the event of a severe earthquake with power outages and destruction, the same protective systems will not allow radioactivity to escape from the reactor block. All Russian-designed 3+ generation NPP projects are designed to ensure safety in the event of an MSK-64 scale 8 earthquake. Reinforced protective structures of the shell, as well as suspensions and supports, which prevent damage to building equipment and internal structures, allow to withstand the strongest shocks.
What makes ВВЕР safe?
The ВВЕР-1200 project belongs to the latest 3+ generation reactors. This is the leading product of Russian scientists, which today is recognized by the world nuclear community as the safest.
Russian reactors combine automatic active and passive safety systems. Active: requiring a power source, passive: not requiring a power source. In the ВВЕР-1200 project, scientists managed to combine all existing knowledge and make changes that provide protection against the release of radioactivity outside the reactor building in any situation.
Passive safety systems, for example, include a double reinforced concrete shell placed on top of the reactor block in the form of a dome. If something happens in the reactor hall, all the radioactivity will remain inside this hermetic shell. Imagine that all the water supplied to the reactor turns into steam and, like in a kettle, it will press against the walls and lid from the inside, but the inner shell will withstand this tremendous pressure. If the threat is external, then the outer shell is already able to withstand a plane crash, storm, explosion, etc. Thus, the dome of the power unit is always ready to receive a blow both from the outside and from the inside.
An important element of the reactor core is the “melt trap”, which is designed in case of an almost improbable meltdown of the core. It is shaped like a huge cup and is filled with a substance that chemically reacts with the melt and allows it to cool the melt almost instantly and bring it to a solid state. Since the “trap” is located directly under the reactor, in the most difficult situation, the molten mass will fall under its own weight into this refractory vessel. The presence of a “melt trap” allows you to guarantee that even in the most unlikely situations, the radioactive elements of decay will be kept within the confines of the hermetic case.
Thus, the world experience of construction and operation of nuclear power plants shows that the choice of the ВВЕР-1200 project is justified by the most important factors of safety and reliability.