Technology and safety

Advantages of the Russian technology

 

Akkuyu NPP is a serial project of a nuclear power plant based on the project of Novovoronezh NPP-2 (Russia, Voronezh region). The project provides for 4 power units with a capacity of 1200 MW each. Serial production and successful operation of this technology (Novovoronezh NPP, Leningrad NPP-2) confirm their reliability.

 

The Russian State Atomic Energy Corporation Rosatom has more than 70 years of experience in the international energy market and ranks first in the world in terms of the portfolio of foreign projects (36 power units at different stages of implementation in 12 countries); the state corporation provides 17% of the global nuclear fuel market.

 

Rosatom State Corporation takes the 2nd place in the world and the 1st place in Russia in terms of nuclear power generation, the 2nd place in the world in uranium reserves and the 4th place in terms of its production.

 

The State Atomic Energy Corporation Rosatom cooperates with many countries of the world and implements advanced solutions to meet all the safety needs of the nuclear industry. The scope of activity of Rosatom State Corporation also includes production of equipment and isotope products for the needs of nuclear medicine, research, materials science, supercomputers and software, and manufacture of various nuclear and non-nuclear innovative products. The strategy of Rosatom State Corporation is to develop green energy generation projects, including wind energy. Rosatom State Corporation incorporates over 300 enterprises and organizations.

 

VVER-1200

 

The flagship energy solution of Rosatom State Corporation is a revolutionary VVER-1200 reactor design. It was developed on the basis of the VVER-1000 reactor versions built for foreign customers in the 1990s and 2000s: Bushehr NPP (Iran), Kudankulam NPP (India), Tianwan NPP (China). Rosatom tried to improve each parameter of the reactor, as well as introduce a number of additional safety systems, which make it possible to reduce the likelihood of radiation releases in any accidents and their combinations beyond the reactor containment limits.

 

As a result, the VVER-1200 reactor is different in terms of:

- increased power,

- service life of 60 years,

- capacity maneuver capability,

- high coefficient of use of installed capacity (90%),

- capability to work for 18 months without refueling,

- other improved specific indicators.

 

The VVER technology uses a dual-circuit nuclear steam generating vessel-type installation with a thermal neutron reactor. The coolant and moderator are ordinary water under pressure.

 

The design includes four cooling loops with a steam generator, a main circulation pump (MCP), pressurizer, relief and emergency shut-down valves on the steam pipelines, and tanks of the reactor emergency core cooling system.

 

 

Thus, the VVER-1200 combines the reliability of long-proven engineering solutions with a set of active and passive safety systems finalized taking into account the "post-Fukushima" requirements.

 

The engineering solutions used in VVER-1200 are, namely:

- spent fuel pool inside the containment,

- vented annulus outlet filters,

- unique "core catcher" with sacrificial material,

- unparalleled passive heat removal system, - they all allow calling it a generation III+ reactor plant.

 

NPP safety systems


 

 

The safety system of modern Russian nuclear power plants consists of four barriers between ionizing radiation combined with radioactive substances and the environment:

 

The first one is the fuel matrix preventing release of fission products under the fuel element cladding.

 

The second barrier is the fuel element cladding that prevents fission products from getting into the primary circuit coolant.

 

The third barrier is the primary reactor coolant circuit preventing the fission products from getting into the containment.

 

The fourth barrier is a system of protective hermetic shells (containment), which prevents releases of fission products into the environment. If something happens in the reactor room, all radioactivity will remain inside this containment. All modern Russian VVER-type reactors have a containment. Moreover, the containment is not only designed for external impact - for example, an airplane crash, tornado, hurricane or explosion. The containment can withstand an internal pressure of 5 kg/cm2 and external impact of a shock wave creating a pressure of 30 kPa and a crash of a 5-ton aircraft. The containment volume is 75 thousand cubic meters, and the risk of hydrogen accumulation in it in explosive concentrations is much less than at Fukushima-1 nuclear power plant. In the event of an accident, a sprinkler system is installed inside the containment to reduce vapor pressure, which sprays a solution of boron and other substances from under the dome of the unit that impede the spread of radioactivity. Hydrogen recombiners are also placed there, which do not allow this gas to accumulate and prevent the possibility of an explosion.

 

The principle of defence-in-depth implies the existence of means to manage the consequences of beyond design basis accidents, which provide for localization of radioactive substances within the containment. They include:

- hydrogen removal systems (with passive recombiners);

- overpressure protection systems of the primary circuit;

- systems for heat removal through steam generators;

- systems for heat removal from the containment (provides long-term heat removal in any emergency situations, including when the NPP is completely de-energized);

- core catcher – a container located under the reactor and filled with a substance that allows instant choking of the reaction (provides localization of the melt and prevents the possibility of release beyond the containment in any scenario).

 

Ensuring the safe operation of reactors

 

The VVER reactors use a composition of the core that ensures "self-protection" of the reactor or its "self-regulation".

 

If the neutron flux rises, the temperature in the reactor increases and so does the vapor content. But reactor plants are designed in such a way so that void fraction increase in the core results in accelerated neutron capture and termination of the chain reaction. Specialists call this effect a negative coefficient of reactivity.

 

To quickly and effectively stop the chain reaction, it is necessary to capture the released neutrons. Boron carbide is normally used as an absorber. Rods with the absorber are introduced into the core, the neutron flux is absorbed, the reaction slows down and stops. In order for the rods to get into the core under any conditions, they are suspended above the reactor and held by electromagnets at Russian nuclear power plants. This scheme guarantees lowering of the rods even when the power unit is de-energized: the electromagnets will switch off and the rods will enter the core under the action of gravity (without any additional operations by personnel). This is the difference between domestic and American projects used in Japan at the Fukushima-1 nuclear power plant (the rods were introduced from below).

 

So, the physics of the rector itself provides self-protection based on natural retroactions (“negative reactivity”).

 

At Russian nuclear power plants, two-circuit schemes are mainly used in which heat can be removed directly to the air without use of external sources of water supply. The dual-circuit scheme is fundamentally safer than the single-circuit one used in Japan, because all radioactive media are inside the protective enclosure (containment), and there is no steam in the primary circuit - the risk of “exposing” and overheating the fuel is fundamentally lower. In addition VVER reactors are equipped with 4 steam generators, and the heat removal systems are multi-looped, that is, significant water reserves are provided in them. If water supply through standby pipes is necessary, separate emergency cooling pumps are provided at the nuclear power plant (a pump for each pipe).

 

At Russian nuclear power plants with water-cooled reactors (VVER), three independent trains of safety systems are provided, each of which can perform the functions of the entire system.

 

The safety systems are designed to eliminate the maximum design basis accident.

 

Water reserves are also redundant: first, water will be supplied from the reserve tanks installed in the power unit itself, and then, if this water is still insufficient, water will start to be supplied from three additional tanks.

 

The power of all standby pumps is supplied independently: each is powered by a separate diesel generator. All generators are located in separate buildings, which does not allow their simultaneous failure.

 

Any of these trains (in case of failure of the others) provides complete heat dissipation.

 

Activation of all these safety systems together will be required only in the event of a maximum design basis accident. All the amount of water spilled into the reactor is accumulated by a special collection and cooling system. The system will supply the collected water to the core again, that is, recycling will be ensured.

 

Principle of power generation


 

The principle of generating electricity at a nuclear power plant is similar to a conventional thermal power plant:

- A nuclear reactor, using the energy obtained from the fission of uranium, heats the water of the primary circuit.

- Heated water enters the steam generator, where its heat-exchange with water from the secondary circuit occurs.

- The steam of the secondary circuit from the steam generator enters the turbine that drives the generator.

- The electric generator generates electricity supplied to consumers through power lines.


Ecological safety of nuclear power generation


Today's technologies make it possible to ensure the safety of nuclear energy for the environment and people living in the immediate vicinity of nuclear power plants. A nuclear power plant will not threaten crop safety or the aquatic environment. It should be noted that fines for environmental pollution around nuclear power plants are higher than at other sources of electricity. Therefore, the environmental situation around the nuclear power plant is much better than in other regions, as experts from various organizations constantly monitor it. It is possible to set up tourist recreation areas and beaches near NPP facilities. In this case, there is no risk to human health. An example is the Vandellòs II NPP in Spain, next to which people calmly relax and bathe.

 

Unlike thermal power plants, atomic technologies:

- do not consume oxygen,

- do not emit harmful chemicals into the atmosphere or water bodies,

- significantly save fossil fuels, whose reserves are limited.

 

Thermal power plants (TPPs) appeared at the end of the 19th century almost simultaneously in Russia, the USA and Germany, and soon in other countries. A location of power plants depends on fuel and energy resources and energy consumers, therefore thermal power plants operating on low-calorific fuel are located in areas of fuel bases, since such fuel is not profitable to transport over a long distance. If power plants use high-calorie fuels, such as natural gas, which can withstand long-distance transportation, they are built closer to places where electricity is consumed. Thermal energy has a huge impact on the environment, pollutes water and atmospheric air. So, to operate a coal-fired power plant requires annually 1 million tons of coal, 150 million cubic meters of water and 30 billion cubic meters of air.

 

Nuclear plants do not pollute the environment. The radiation impact of nuclear power plants on the environment and the public is much smaller compared to power plants on oil, coal and fuel oil, which release harmful products of combustion into the atmosphere. Worldwide, nuclear energy can reduce carbon dioxide emissions by 3 billion tons per year. The leaders in this regard are the countries of Europe, where existing nuclear plants prevent a release of up to 1 billion tons of carbon dioxide annually.

 

Nuclear power plant is a closed fuel cycle enterprise. This means that all fuel used remains inside the NPP. The water used for cooling is not exposed to chemical, physical or radiological effects.

Unlike renewable energy sources (sunlight, wind, water energy), nuclear technologies preserve land spaces.

 

The global volume of carbon dioxide emissions is about 32 billion tons per year and continues to grow. It is forecasted that by 2030 the volume of emitted carbon dioxide will exceed 34 billion tons per year. The solution to the problem may be active development of nuclear energy, one of the youngest and most dynamically developing sectors of the global economy. An increasing number of countries today are coming to the need to begin development of civil uses of atomic energy.

The installed capacity of the world nuclear energy is 397 gigawatts. If all this power were generated from coal and gas sources, then an additional 2 billion tons of carbon dioxide would be released into the atmosphere annually. According to the estimates of the intergovernmental group of experts on climate change, all boreal forests (taiga forests located in the northern hemisphere) annually absorb about 1 billion tons of CO2, and all the forests of the planet - 2.5 billion tons of carbon dioxide. That is, if the criterion is the influence on the level of CO2 in the atmosphere, nuclear energy is commensurate with the "ecological power" of all the forests of the planet.

 

What are the benefits of nuclear power?


Huge energy-output ratio of the fuel used

1 kilogram of uranium enriched up to 4% used in nuclear fuel, when fully burned, releases energy equivalent to burning about 100 tons of high-quality coal or 60 tons of oil.


Reuse

Fissile material (uranium-235) does not burn out completely in nuclear fuel and can be used again after regeneration (unlike ash and organic fuel slag). In the future, a complete transition to a closed fuel cycle is possible, which means an almost complete absence of waste.


Greenhouse effect reduction

The intensive development of nuclear energy can be considered one of the means of combating global warming. For example, nuclear plants in Europe annually prevent an emission of 700 million tons of CO2. The operating nuclear power plants of Russia annually prevent an emission of about 210 million tons of carbon dioxide into the atmosphere. By this indicator, Russia is in fourth place in the world.

 

Economic development

The construction of nuclear power plants provides economic growth and creation of new jobs: 1 workplace during NPP construction creates more than 10 jobs in related industries. The development of nuclear energy industry contributes to growth of scientific research, production and export of high-tech products.

 

Many leading economies of the world have opted for nuclear technologies, such as environmentally friendly France, where nuclear power production exceeds 70% of the total output, and 6 nuclear power plants are operated at a distance of less than 200 kilometers from Paris. In Spain, 3 nuclear power plants are operated at a distance of less than 200 kilometers from Madrid. Bradwell NPP is 70 km away from London.

 

Tasks and activities in the field of environmental safety of nuclear power plants

 

Environmental safety at all stages of NPP construction is the main principle and basic condition for nuclear industry development.

 

As part of implementation of nuclear power plant projects, priority tasks in the field of environmental safety have been identified:

- Compliance with all applicable laws, norms and rules of the Republic of Turkey, the Russian Federation and international organizations: IAEA, EUR;

- Timely receipt of the necessary permits for the implementation of the Akkuyu NPP project in the relevant institutions of the Republic of Turkey;

- Unconditional fulfillment of all requirements and norms of safe operation of NPP;

- Permanent environmental monitoring at Akkuyu NPP and in adjacent territories;

- Publication of environmental safety annual report;

- Regular informing the public about the facts of the impact of nuclear power plants on the health of personnel, the public and the environment.

 

To monitor the state of the environment during the implementation of the project, a whole range of environmental measures is provided:

- Reclamation and remediation of land damaged during construction;

- Protection of the environment against radioactive and chemical waste under normal operation conditions;

- Organization of air emissions from rooms with a high degree of purification from radioactive products;

- Prevention of radionuclides release into the environment with water;

- Reliable storage of waste without contact with the environment;

- Exclusion of non-radioactive emissions of polluting substances;

- Continuous comprehensive environmental monitoring.

 

To control the environmental situation around the Akkuyu NPP, dedicated stations will be created for continuous environmental monitoring to cover the following areas:

  • hydrological measurements;
  • atmospheric measurements;
  • measurements of the level, temperature and chemistry of surface and groundwater;
  • seismic measurements;
  • monitoring of foundation settlement and warping of structures;
  • monitoring of present-day crustal motion and the gravitational field;
  • radiation monitoring;
  • monitoring public health.

 

The Akkuyu NPP construction project is being implemented in compliance with all of the above priorities and measures in order to ensure safe and reliable operation of the NPP with minimal impact on the environment, people and personnel.